Rice Produce Within The Rice Producing Area, Onueke, Ebonyi State, Nigeria
Rice Produce Within The Rice Producing Area, Onueke, Ebonyi State, Nigeria
Rice (Oryza sativa) is one of the leading food crops of the world, it is a cereal crop for human consumption and is a staple food of over approximately one-half of the world population (Cantral and Reeves, 2002, Davidson et al., 1979). To place an order for the Complete Project Material, pay N5,000 to Then text the name of the Project topic, email address and your names to 08060565721.
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To place an order for the Complete Project Material, pay N5,000 to
Then text the name of the Project topic, email address and your names to 08060565721.Golden rice was genetically engineered to contain beta carotene, not present in standard rice, to combat the widespread vitamin A deficiency and eradicating blindness in children of the developing world (Beyer et al, 2002; central and Reeves, 2002). Beri-beri, as a disease from the consumption of white rice is now rare if the rice is parboiled or enrich (Dividson et al; 1979 Juliano and Perez 1986).
Rice is grown in all the ecological and dietary zones of Nigeria, with different processing adaptation trait for ecology (Sanni et al; 2005). The two commonly cultivated varieties of rice in Nigeria are Oryza Sativa and Oryza glabberima (Adeyemi et al; 1986; Abulude, 2004). Rice is an economic crop, which is important in household food security, ceremonies, nutritional diversification, income generation and employment (Perez et al; 1987). It is utilized mostly at the household level, where it is consumed as boiled or fried or ground rice with stew or soup. Rice is cooked by washing and boiling in water which lead to loss of some nutrient (Ihekeronye and Ngoddy, 1985; Perez et al; 1987). The proximate composition of rice has been previously reported (Oyenuga, 1968; Temple and Bassa, 1991; Adeyeye and Ajewole, 1992; Bishnoi and Khotar Paul, 1993; Adeyemi et al; 1986; Abuliede, 2004).
Despite the fact that different varieties of rice are widely cultivated in Nigeria, for example Abakaliki rice, but there is an upsurge in the influx of foreign rice varieties into the country.
Majority of the Nigerian prefer to consume foreign rice brand compare to any local rice varieties produced in Abakaliki.
It is therefore imperative to ascertain why this preference exist and to determine if there is significant difference among the rice varieties. In addition, quality characteristic of processed rice can be determined, now that consumers have choice of quality of product, since quality is dependent on processing skill and method and varieties, it is the object of this present study to evaluate the quality of rice produce within the rice producing area at Onueke in Ebonyi State, Nigeria.
To determine the physicochemical properties of the rice processed.
To determine the cooking properties of processed rice
To determine the sensory quality of rice.
Rice breakage during milling process is affected by different parameters such as paddy harvesting conditions, paddy drying, physical properties of paddy kneels, the environmental conditions and the types and quality of the moving system components. Many studies have been conducted in this area. Davis (1944) reported that the optimum harvest moisture content for the paddy of the caloro variety was 20 to 24% Pominski et al. (1961) showed that the paddy moisture content had a significant effect on milling yield of Bluebonnet 50 long-grain rice. They selected samples with moisture content ranging from 10 to 14% and concluded that for each one percentage decreases in rice moisture contain, head yield and total yield increased 3 and 0.7%, respectively. Mathews et al (1970) found that rice breakage at milling was mostly due to mechanical stresses matter than thermal stresses. Mathews and Sparado (1975) evaluated the effect of the harvesting method of rice breakage during the milling process: they found that the samples that had been harvested by combine contained 5% more broken kernels than the samples that had been harvested manually. Mathews and Sparado (1976) also found rice breakage during milling process increased when the kernel decameter decreased Dilday (1987) studied the effect of moisture content of the rice breakage during the milling process he used samples with moisture of 12 to 16% and concluded that rice breakage decreased with increase of paddy moisture content Luh (1991) reported that to have a high quality head rice with animal breakage, paddy must be harvested at the optimum moisture content. Clement and Segug (1994) found that long and tiny rice kernels were more susceptible to breakage during the milling process as compared to work short kernels. Peilty et al (1994) reported that paddy drying conditions affected the rice breakage increased rapidly with decreasing moisture content in the air used to dry the paddy. Autreg et al (1995) showed that the difference in temperature and milling environment temperature decreased the performance of rice milling yield.
Harvesting generally refers to the operation carried out in the field which includes cutting the rice stalk or reaping the penicles either laying out the paddy on stalk or stacking it to dry, and bundling for transport. Harvesting and it’s handling operations and processes should be understood to prevent considerable amount of post-production losses. When there is too much paddy handling it create problems on both in quality and quantity (NAPHIRE, 1997) harvesting and its related handling operation are significant points in the post production sequence because grain loses can be incurred. Each additional handling step produces a loss of 1 to 2 percent, for highly shattering varieties (Samson and Duff, 1973). The sequence of manual harvesting field drying bundling and stacking in traditional system can incure losses from 2 to 7 percent. (Toquero and Duff).
Cleaning of rice to remove foreign seed and thrash is important because subsequent effect on the storagibility and milling quality, rice with impurities likely to deteriorate in storage. Impurities also reduce the milling recovery particularly of there are stones mixed with rice. Unclean rice also increase maintenance requirement on milling machines.
Rice grain cleaning is based on the function of air velocity, which is used to separate materials by weighed density and wind resistance. Air cleaning takes advantage differences in weight and aerodynamic characteristics of the grain in separate from other materials.
Mechanical cleaning uses sieves for separation based on size and shape, while gravity cleaners such as rough rice separators use is made of the difference in specified gravity and bulk density of the gravity to separate materials that have little difference size and total weight.
Cleaning is mostly done manually by hand winnowers in most tropical countries of Asia and Africa. Other rough rice cleaners include the winnowing basket, modern or metal boxes with perforations and a combination. In modern rice milling machines are used which include sieves, disc separator, indented cylinder, as pirator magnetic separator, fluid bed gravity, separator, destoners (Shrubbier Buckle 2003, Daminy, 2003).
Parboiling had as its original intention, the loosening of the halls, but in addition, enhances the nutritive value of the milled rice so treated because water dissolved the vitamins and minerals concentrated in the bran and hulls and redistributes these in the endosperm. Through this mechanism, the minerals and vitamins which would have otherwise been lost during milling through bran and hull removal are retained in the milling rice (Okaka, 2005). Prior to milling, or sorting, rice be parboiled, which involve soaking the rice in warm water, steaming and drying. Parboiling is prior to cooking preserves some of the nutrient content, as macronutrient are transferred from the aleurone and germ into starcy endosperm. (Julano and Bechtel, 1985). It was reported that the thiamine and riboflavin have the highest in parboiled rice milling up to 6 percent when compared with parboiled brown rice mill up to 8 percent, raw brown rice and raw milling rice (Grewal and Sangha, 1990).
The drying of parboiled rice is slightly different from the drying after harvesting. To achieve the best milling result the moisture of the paddy should be about 14 – 16%. The drying methods use to achieve this; are sun drying and mechanical drying. The drying of paddy using the sun’s energy is widely achieve or practiced by both industrial rice mills and small scale processors in Nigeria and most Asian countries.
In Nigeria, the simplest method of sun drying is to spread the raw paddy on the drying floors of different types ranging from mud floors to concrete floors. For high moisture paddy, depths of about 3 – 10cm are normal and the paddy is stirred systematically to expose new surfaces as it dries. However, the drying of steamed parboiled paddy is some what different because it has high initial moisture content. Usually the paddy is spread to depth of about 2 to 3 cm on drying floors, stirred. Paddy is sometimes allowed to be conditioned. The paddy dries 6 to 7 hours during the dry season and 9 to 18 hours during the raining season.
It is important to dry rice under shade during dry season to prevent the formation of fissures, which may lead to excessive breakage of the parboiled rice during subsequent milling (Araull et al, 1976).
After harvesting, rough rice a paddy or dried, either mechanically or by open air drying. Dried rice is then milled to remove the inedible hulls. Hulled rice is also called “brown” rice and consists of an average weight of 6-7 percent bran, 90 percent endosperm and 2-3 percent embryo (Chen, Siebernmorgan and Griffin, 1998) further milling, removing the bran layer, yield white rice. On average, paddy rice produces 25 percent hulls 10 percent bran and 65 percent white rice (Saunders and Betschart, 1979) after industrial milling, 100kg of paddy yield about 60kg of white rice, 10kg of broken grains, 10kg of a bran and flour, and 20kg of hulls (FAO, 1994b). There are several degree of milling, depending on consumer preferences and desired degree of whiteness. Milled rice is referred to as polished or whitened rice and there are various degrees or fraction of polishing. White rice implies 8-10 percent bran removal. In general, as greater amounts of rice bran are removed from the grain during polishing, more vitamins and minerals are lost. A study in India found that up 65 percent of thiamin and 40 percent of phosphorus were lost when rice was polished to 6.3 percent (Rao, Desikachar and Subrahmanyan, 1960). Milling losses of protein is estimated between 10 and 15 percent (Malik and Chaudhary in press).
Rice (Oryza Sativa); is the most important food crop in the world, providing over 21% of the calorific needs of the world population and up to 76% of the calorific intake of the population of South east area. In countries where rice is consumed, traits of grain quality dictate market value and have pivotal role in the adoption of new varieties. Quality trait encompasses physical characteristics.
Rice quality is evaluated on the basis of its suitability for a specific end use for a particular consumer. It is therefore related to the quality of milled whole grains because nearly all rice for domestic consumption is milled. The quality of rice is evaluated according to grain cleanliness and soundness, moisture content and drying characteristics, purity of variation grain shape, size and uniformity rice.
The milling degree is a measure of percent bran removed from brown rice kernel. Milling degree affects milling recovery and influences consumer acceptance. Apart from the amount of white rice recovered, milling degree influences the colour and also the cooking behavior of rice. Unmilled brown rice absorbs water poorly and does not cook quickly as milled rice. The water absorption rate improves progressively up to about 25% milling degree after which there is very little effect.
Head rice is the percentage that weight of head grain or whole kernels in the rice. Head rice normally includes broken kernels that are 75-80% of the whole kernel. High head rice yield is one of the most important criteria for measuring milled rice quality. Broken grain has normally, only half of the value of head rice.
The actual head rice percentage in a sample of milled rice will depend on varietal characteristics, production factors, and harvesting drying and milling process. In general, harvesting, drying and milling can be responsible for some losses and damaged to the grain.
This is another trait of appearance that affect consumer acceptance of rice. Chalky grain has opaque spots in the endosperm that range in sizes (Lisle et al; 2007). Chalk predisposes the grains to break during polishing (Wang et al, 2007), decreasing the amount of edible rice, even if the chalky market value (Yamakawa et al 2007).
Whiteness is a combination of varietal physical characteristics and the degree of milling. In milling, the whitening and polishing greatly affect the whiteness of the grain. During whitening, the silver skin and the bran layer of the brown rice is remove. Polishing some of the bran particles stick to the surface of the rice which polishes and gives shinier appearance.
The time required for cooking milled rice is determined by gelatinization temperature. The gelatinization temperature, environmental conditions, such as temperature during ripening, influence gelatinization temperature. A high ambient temperature during development results in starch with a higher gelatinization temperature.
Gelatinization temperature of milled rice is evaluated by determining the alkali spreading value. In many rice growing countries, there is a distinct preference for rice with intermediate gelatinization temperature.
Gel consistency measures the tendency of the cooked rice to harden after cooling. Within the same amylase group, varieties with softer gel consistency are preferred and the cooked rice has a higher degree of tenderness. Harder gel consistency is associated with harder cooked rice and this feature is particularly evident in high amylase rice. Hard cooked rice also tends to be less sticky. Gel consistency is determined by heating a small quantity of rice in a dilute alkali.
Starch makes up about 90% of the dry matter content of milled rice. Starch is a polymer of glucose and amylase is a linear polymer of glucose. The amylase content of starches usually ranges from is 0 to 35%. High amylase content rice shows high volume expansion not necessarily and high degree of flakiness. High amylase grain cooks dry, is less tender and become hard upon cooling. In contrast, low amylase rice cooks moist and sticky amylase rice is preferred in most rice growing areas of the word, except where low amylase. Amylase content is determined by using calorimetric.
COOKING EFFECT ON RICE
The starch in the rice grain are; amylase and amylopectin. The starch is the main factor that affects the cooking quality of rice. Studies have shown that amylase has a huge impact in the cooking quality of a rice variety but it cannot be used as a sole predicator. It is therefore important to determine the effects of the other grain components on the cooking quality.
AMYLOSE AND GRAIN QUALITY
Amylase is mainly a linear form of starch. The amount of amylase in the grain determines how stocky the rice will be when cooked. When amylase increases the rice grain becomes less stocky and more firm. Some varieties do not have amylase in them because of waxy gene.
AMYLOPECTIN AND GRAIN QUALITY
Amylopectin is a highly branched form of starch. Its structure is organized into different levels; with each level contributing to the overall effect of amylopectin on cooking qualities has been investigated.
Rice is cereal grain that is subjected to deterioration because of change in temperature and relative humidity. Insects, mould and other diseases are also more active after increase temperature and relative humidity.
Storage facilities range from sacks, bamboo baskets, cans drums and small granaries for large quantity of rough rice is a special room within the farmer’s house is used.
In warehouse, gummy sacks the most common. In Japan and other temperature rice growing countries, rough rice is stored in large storage facilities (bulk storage silos) which are protected from major losses due to pilferage, rats, birds and insects are major problems in tropical countries of Asia and Africa. Storage insects and moulds contamination can be minimize through good houses keeping practices which include the following:
Proper construction and management of storage structure
Proper drying of grain
Proper physical control
Proper chemical control.
In modern rice processing in bulk storage in silos is essential to provide continuous supply of paddy or brown rice and also in modified atmosphere storage is in use to prevent spoilage. (Monte mayor, 2004).
After milling, the rice is graded in thickness and length. Through the process broken rice is separated from the head rice to a very high percentage of accuracy. This is carried out in many industrial rice mills with advanced technology from Buhler and Sataka. They include, in Drum graders, plansiflers and indented cylinders working at different stages. The uniform grain length renders a rice appearance to the finished product and adds to the presentation before and after cooking.
The main by-product of rice milling is rice bran and brewer’s rice. The bran is produced in the pealing process. It comprises the pericap aleurone layer, embryo and some of the endosperm, and contains most of the vitamins and proteins of the grain (Grist, 1989, Juliano 1993).
Table 1: The percentages composition of bran includes:
Nitrogen free extract 38.7-44.3
Vitamin B 544mg
Source: Shakundala and Shadaksharawamy (1987)
Broken grains obtained during the milling process are removed as by-products, the largest fragments are known as second head, the medium as screening and the smallest as brewer’s milled or simply as brewer’s rice. The brewer’s rice called because it is used as brewing adjunct to improve the shelf life of the beer and to impart stability (Kent, 1983). Brewer’s rice is separately produced when milled rice is sifted.
UTILIZATION OF RICE BY-PRODUCT
Rice bran contains higher protein value. Besides protein, rice bran is an excellent source of vitamins B and vitamins E as well as oil, the oily nature of the bran make it a good binder for animal feeds. The conventional use at rice bran is as ingredient for animal feeds, in particular ruminants and poultry. Rice bran with its high fat content is useful in feeding performance horses that need to gain extra weight. It is also useful in feeding horses that require excellent hair and skin conditions.
Defatted rice bran contains higher protein and other nutrients. It has a good amino acid profile for monogastric animals and good protein and phosphorus contents for ruminants. It is however low in essential fatty acids.
When stabilized, defatted rice bran can provide nutritional fortification at levels up to 15% for bakery product such as yeast-raised, goods, muffins pancake mixes and biscuits. The rice bran improves the flavour, increases the water absorption, without loss of volume in products. It also significant amounts of essential amino acids, vitamins and minerals to the products (Kent, 1983), It has been observed that addition of the defatted rice bran to bakery goods does not affect the mixing tolerance or the fermentation process. Defatted rice bran is also used in breakfast cereals.
Rice bran contains 10-23%bran oil. The can be extracted by mechanical or solvent methods. The crude rice bran oil contains a large amount of free fatty acids which renders it unsuitable for edible purpose (Grist, 1986). In contrast refined rice bran cell is light, bland, stable oil, suited for use in shortenings cooking and salad oils and as a pan release agent in bakery operations. Its stability, result from its high content of oleic and linolenic fatty acids as well as its low content of unstable linolenic acid (Kent, 1983). The stability is also due to its relatively high content of alphatocopherol and other natural antioxidants (gamma-oryz and tocotrienols) (Scavariello and Arellano 2998).
The starches in rice grain are amylase and amylpetin. The proportions and structure of the two types of starch, the main factors that affect cooking quality of rice amylase has a large amount impact in cooking quality of rice variety but it cannot be used as sole predictor, it is necessary to determine other grains components on cooking quality.
Amylose and grain quality
Amylose is mainly a linear form of starch. The amount of amylase in grain determines how sticky the rice will be when cooked. As amylase content increases, the rice grain becomes less and more firm.
220.127.116.11 Amylopetic and grain quality
Amylopetic is a highly branched form of starch. Its structure is organized into different levels, with each level contributing to the overall effect of amylopetin on cooking properties.
2.9.8 NUTRITIONAL QUALITIES OF RICE
With high nutrients, rice is a good source of insoluble fiber, which is also found in whole wheat, brand and nuts. Insoluble fiber reduces the risk of bowel disorders and fights constipation. Among other nutrients, rice is rich in carbohydrates, the main sources of energy, low in fat, contain some protein and plenty of B Vitamins.
NUTRITIONAL QUALITIES OF RICE
Whiter rice Sasmine Brown Alutmous
Calories, kcal 361 355 362 355
Water g 10.2 11.9 11.2 11.7
Total fat g 0.8 0.7 2.4 0.6
Dietary fiber g 0.6 08 2.8 0
Calcium mg 8 5 12 7
Phosphorus mg 87 65 225 63
Potassium 111 113 326 0
Sodium mg 31 34 12 0
Vitamin B1,mg 0.07 0.12 0.06 0.08
Vitamin B2 mg 0.02 0.02 0.04 0.03
Niacin g 1.8 1.5 5.5 1.8
Protein g 6 6.1 7.4 6.3
Carbohydrates 82.0 18.1 77.7 81
Source: Ihekoronye and Ngody (1985)
Rice is an extremely healthy food for a number of reasons. Rice is a complex carbohydrate which means that it contains starch and fibre.
Complex carbohydrates are digested slowly, allowing the body to utilize the energy release over longer periods which is nutritionally efficient.
Rice has low sodium content and contains useful quantities of potassium, the vitamins, Thiamin and niacin. An average proportion of rice (50g) provides about 11% of the estimated average daily requirement of protein. On potion also has only 245 kcal . Those looking to reduce their fat and cholesterol intakes can turn to rice because it contains only trace of fat and no cholesterol. Rice is also gluten free, so suitable coeliacs, and it is easily digested, and therefore a wonderful food for the very young and elderly.
A new process that adds value to rice and creates a means of rice for defecation has be developed, in the process enriched artificial rice grain pellets production by extrusion process is added in small amount to milled raw rice. This process as is hoped will prevent malnutrition among those white rice (doming, 2004).
The success of various fortification strategies, particularly those involving fortification with iron, is mixed. The fortification of roods with the iron remains technically complex, those iron compounds with the greatest bioavailability (ferrous sulphate and ferrous fumarate) significantly alter the palatability of food, whereas large declines in the uptake of iron are seen when a more palatable iron compound (elemental iron or ferric or thophosphate ) is used (Dary, 2001). The level of technical difficulty encounter red in fortification programme. The level of technical difficulty encounter red in fortification programmes depends on successful include: Ensuring supply and access to the product, monitoring and support from the government and consumer knowledge and demand for the product (marberly, 2000). Another key element is involvement of the appropriate industry sector. The enriched product must be available, affordable and palatable.
POST HARVEST LOSSES
This is the quality and quantity loss in a given, product (FAO, 19949).
The loss can occur at any point at harvest, threshing , drying and storage. An estimated percent of total rice production is lost as a result of post harvest factors (Saunders and Betschart, 1979). During harvest, depending in the type of machinery or human resources used, small amount of the grain will be left in the field. Similarly, losses may occur during the process, which in developing countries commonly takes place on the roadside. Further losses are incurred during the storage process because of moulds, insects and rodents.
Estimate from sub-Sahara Africa have shown that rodents can consume or contaminate up to 20 percent of a stored harvest (FAO,1004b).
MATERIALS AND METHOD
Rice (Oryza sativa) of different varieties was gotten from Onueke rice mill for eight days and was bulked together to get a representative sample. The varieties are 305, IR5 and FARO5.
The sample that was collected consecutively from rice mill was bulked together variety wise after eight days and a representative sample was randomly gotten and was used for all analysis that was done, some analysis was done in duplicate and some in triplicate
Length and Width of Raw Milled Rice: FOA (1972)
Method that was used for grains of raw rice that was used to bulked together ten grains each from the varieties collected were selected and length and width was measured using vennier caliper calibrated in (mm)
Determination of Appearance
The head rice yield and percentage broken milled rice was calculated by determining the whole and broken milled grain respectively from 20g portion, by hand picking as described by Bhaltachary and Subba Rcea (1996).
3.4 CHEMICAL PROPERTIES
3.4.1 Determination of Moisture Content
The hot oven method (Pearson, 1976) was used to determine moisture content. Petri dishes were washed and were properly dried in an oven at 100oC for a period of 30 minutes and were cooled in desiccators. The weights of the Petri dish were determined by using the mettle weighing balance and it was labeled (w1). 5g for the sample were weighed and it was poured into the Petri dish and both the Petri dish and rice sample was weighed and it was labeled (w2). And it was placed in the oven at temperature of 105oC for 5 hours, thereafter it was transferred to desiccators for 30 minutes and it was cooled and it was reweighed and it was labeled (w3).
The moisture content was calculated as follows:
Weight of Petri dish = w1
Weight of Petri dish + sample = w2
Weight of Petri dish + sample after drying = w3
Moisture content (%) = (w_2-w_1)/(w_2-w_1 )×100/1
(Difference in weight)/(weight of sample)×100/1
Determination of Ash Percentage
Determination of ash was done using AOAC (1984) method. The flour passed through a USA standing seive no 20 (850mm) that gave same size particle which was used for ashing. About 1g of rice flour was weighed into a Petri dish already weighed and was reweighed and it was placed in the furnace. Heating started gradually until a temperature gets to 600oC and it was maintained for 3 hours. It was then transferred to desiccators for 30 minutes and it was allowed to cool and it was weighed. The percentage ash was calculated as follows:
Weight of Petri dish = w1
Weight of Petri dish + Sample = w2
Weight of Petri dish + Sample after ashing = w3
% Ash=(w_3-w_1)/(w_2-w_1 )×100/1
3.4.3 DETERMINATION OF VITAMINS
18.104.22.168 Determination of riboflavin
Riboflavin was extracted with dilute acid and removed the interfering substances by treatment with KMnO4, it was determined in a fluorimeter at 450 – 500nm wavelength. The intensity of fluorescence is proportional to the concentration. It was calculated as follows:
Riboflavin (mg per g of sample)= x/(y-x)×1/w
Where w=Weight of sample
x=(reaading of sample 1)-(reading of sample blank)
y=(reading of sample+standard tube 2)-(reading of sample+standard blank)
Determination of Fat
Fat was determined using Soxhlet apparatus, an improved Soxhelt method. About 2g of each flour sample was weighed and poured into a thimbles covered with cotton wool. The thimble was inserted into the extraction machine. The extraction cups was filled with 20 – 25 ml of solvent (hexane) and it was clamped into the condenser. The thimble was dipped into the cup and it was boiled for 20 minutes. The limit was filled to rinsing position and was covered after condenser valves are closed. The cups were dried in an oven at 130oC for 15 minutes before it was placed in desiccators for cooling and it was weighed using mettle balance.
The percentage fat was calculated as follows
%fat=(Weight of fat)/(Weight of sample)×100/1
3.4.5 Determination of Protein
Protein was determined using Kjeldahl method. The Kjeldahl involve the principles of three steps and they include digestion, distillation and titration.
About 0.5g of each sample was weighed into the digestion tubes.
About 7g of potassium was added
About 0.3g of mercury to oxidize
About 25ml of concentrated sulphuric acid was used digest the sample at 42oC for 45 minutes. Sample were cooled and diluted with 75ml of distilled water, with 50ml of caustic soda was added and steam was distilled. About 150ml of the distillate were collected and titrated against 0.1 of HCl a blank was used as control.
The percentage protein was calculated as follow
%Nitrogen=Titre value-blank+(14.007 x 25)/(weight of sample) x 100/1
Determination of Crude Fiber
Crude fiber AOAC (1984) official method of Analysis 14th edition Association of Official Analytical Chemist, Washington D.C., The AOAC (1984) method will be used. The residue from either extraction was transferred into 500ml flask filter with condenser, 200ml of 120% sulphuric acid and 3 drops in anti foam were added. It was heated to boil for a minute. The content was gently boiled for 30 minutes under cold finger condenser. The flask was rotated occasionally. The content of the flask was then fluttered through bucher funnel prepared with filter paper number 541 and washed six times with boiling water, two times with 1% HCl and six times again with boiling water to remove acid. Three times with industrial alcohol (methanol) and four times with petroleum ether. Residue placed in porcelain dish that was previously weighed and dried at 105oC night, cooled and weighed. The loss in weight after ignition is the crude fibre content of sample was expressed as:
% fibre content=(w_2-w_3)/w_1 ×100/1
Determination of Carbohydrate
This was determined by the difference that is, the total percentage of moisture, crude fiber protein, and ash, fat was deducted from the carbohydrate.
3.4.8 Determination of Minerals
22.214.171.124 Determination of Calcium and Zinc
About 1g of dried samples was weighed into a digestion flask and 20ml of acid mixture was added (650ml Conc HNO3). It was heated until the digestion was cleared; the digestion was diluted with distilled water of 500ml mark. SrCl2 solution containing 10,000mg/ml was added to yield 1,500mg/ml of Sr2+ in the final solution.
It was calculated as follows:
(Absorbance of test×Conc.of std.(5mg/d1) )/(Absorbance of std.)=P(mg/d1)
About 5g of raw rice sample were weighed and it was poured into a measuring cylinder that was filled with water of 25ml mark. The volumes that were displayed by the measuring cylinder were noted. The rice grain and water was transferred from measuring cylinder to the flask for cooking of the grains.
The cooking was done on the magnetic stirrer hotplate; the time at which it starts was noted. The grain was watched to note when the grain started swelling which was as a result of loosing of starch bound in the grains which enable rice starch to absorb water and cause the rice to increase in shape of the grain. At this time gelatinization time was noted along with the gelatinization temperature with a thermometer.
The grains were checked to know when it was properly cooked by feeling it the grain in between two fingers. When it was soft and the time was recorded. The cooked rice was removed and allowed to cool. Cooked rice sample was transferred into measuring cylinder containing 25ml of water portable, the volume was displaced by the cooked rice was also be determined and noted.
The water was drained off and the cooked rice was collected on a filter paper and it was weighed and it was recorded. It was taken to oven for drying; at was allowed to cool and weighed.
3.5.1 Bulk Density
Nkama (1990) method was weighed into a graduated measuring cylinder and the equivalent of sample was in a measuring cylinder. The density was calculated as:
Density=(Weight of sample)/(Weight of equivalent beaker)
and was expressed in g/cm3.
3.5.2 Swelling Capacity
This was determined by grinding some sample and pour into a 100ml mark of the measuring cylinder. Water was added to 800ml mark of the measuring cylinder containing each of the samples. It was left for 30 minutes. The percentage increase in volume was recorded as the swelling capacity.
3.6 Sensory Evaluation
Sensory evaluation was determined using the rice varieties, when the rice grain was cooked the panelist determined the quality of different varieties of rice. The colour, taste, appearance, texture, mouth feel and general acceptability were varied significantly.
RESULTS AND DISCUSSION
Table 3: Physical properties of raw rice
Varieties of samples Length of rice(mm) Width of rice(mm) L/W ratio of
Faro 5 7.16ab 2.30ab 3.11
IR5 636b 2.22b 2.86
305 7.72a 2.33a 3.31
1.13 0.09 –
Table 4 Physical properties of cooked rice and two cooking properties:
Faro5 IR5 305 Rice LSD
Length of cooked rice (mm)
7.21c 8.13b 8.43a 0.13
Width of cooked rice (mm) 3.20 3.53 3.26 –
l/w ration of cooked rice 2.23 2.30 2.59 –
L/w elongation ratio 1.01 1.28 1.09 –
W/wose elongation ratio 1.39 1.59 1.40 –
Actual elongation 0.05 1.77 1.71 –
Gelatization temperation (oC) 76.00 76.67 79.00 –
Gelatization Time (mins)
28.00 28.67 27.00 –
Means in the same column with the same superscript are not significantly different at 5% level (P < 0.05).
Physical and cooking of the rice varieties properties
The physical properties of raw and cooked rice and two cooking properties of rice varieties are shown in Table 3. Significant variation in length of raw and cooked rice and width of raw rice, were observed while L/W ratio of raw rice, width of cooked rice, L/W ratio of cooked rice lengthwise and width wise elongation ratios, actual elongation, gelatinization temperature and time were observed to have shown no significant difference variation.
Uniformity in shape and size is considered as the first quality characteristics of rice. The result on Table 3 shows that, length and width of raw rice varieties tested were high. Highest length (7.72mm) was observed in 305 followed by Faro5 (2.30mm). Among the varieties, lowest length and width were measured IR5. Statistically, the varieties differed significantly at 5% level (p<0.05) in their length. It can be deduced that 305 with length 7.72mm is significantly different and longer than IR5 but significantly the same with Faro5. Also, Faro 5 is significantly the same with IR5 in length (Appendix). Width of the raw rice varieties showed significant difference at 5% level (p<0.05). 305 variety is significantly different from IR5 at (p<0.05) but are the same with Faro5 (p>0.05). More so, Faro5 is significantly the same in width with IR5 (Appendix).
The length / width ratio of which is a measure of the shape and size fall between 2.86 and 3.31 in raw rice sample (Table 3). Whose ratios are greater than 3.0 are classified as slender, ratios between 2-3 are bold grains while ratios <2 are round (Dipti etal. 2003).
All the varieties tested fall within the slender shape or size except IR5 which fall within the bold shape or size. From the classification based on length, long grains ranges from (6mm and above), medium (5-6mm in length) and short grain (below 5mm in length) (Webb and Stermer, 1972). With the classification, all the varieties tested were long grains but 305 were very long followed by Faro5 and because of its long nature or characteristics, it can be used in place of the Thailand long grain. The shape of the grain, that is, its length/width ratio, influences its volume and weight in a mass. Slender varieties of rice occupy more volume than round varieties.
Therefore, one tone of a slender variety of rice will need more storage space than the same weight of a round variety of rice. Conversely, one litre or one lorry-load of a slender variety will have less weight than one litre or lorry-load of round variety. In other words, if rice is traded in volume rather than in weight, the seller will gain if it is a slender variety. Size and shape of rice affect many other properties, namely, sieving, dehusking, polishing, storage as well as cooking (Nkama, 1993). Consumers’ preference for grain size and shape vary from one group to another. All the three varieties tested were long slender grains. According to Biswas et al (1992), the grain size and shape of most modern rice varieties is short to medium bold with translucent appearance. Statistically, the L/W ratios of the varieties showed no significant difference at 5% level (P>0.05)
The average length of cooked rice varieties tested ranged between 7.21 and 8.43mm with the highest length found in 305 (Table 4.2), followed by IS (8.13mm) while the least was obtained in Faro5 (7.21mm). The results therefore, show that 305 and IR5 increased tremendously more than Faro5, they increased from 6.36mm to 8.13mm (IR5) and 7.72mm to 8.43mm (305) respectively. This may account for their high cost in the market as Choudbery (1979( in his work, stated that urban people (dwellers) prefer varieties that expands more in length than width (breadth). The length of cooked rice showed significant variations at (P<0.05). 305 variety is significantly different and longer than IR5 and Faro5. Moreso, IR5 is significantly different and longer than Faro5 in average length after cooking.
The average width of cooked rice of all the tested varieties ranged between 3.20 and 3.53mmm with the highest width recorded in IR5 while Faro5 had the least width after cooking (Table 3). The statistical analysis of the average width or cooked rice showed no significant difference at 5% level (P>0.05).
The length/width ratio of the cooked rice varieties tested ranged between 2.25 and 2.59 with the highest and lowest length/width ratios found in 305 and Faro5 respectively. Statistically, the L/W ratio of the cooked rice varieties did not differ significantly at (P>0.0.5).
The elongation or lengthwise elongation ratio of the varieties ranged from 1.01 to 1.28. Highest elongation ratio was found in IR5 (Table 3) while Faro5 had the least. Elongation ratio is an important parameter for cooked rice. If rice elongates more lengthwise it gives a finer appearance and if it expands widthwise, it gives a coarse look (Anonymous, 1997). However, all the varieties showed high elongation ratio upon cooking. Statistically, all the varieties were significantly the same in their elongation ratio.
The elongation ratio otherwise called lengthwise elongation ratio is the ratio of the length of cooked rice over the length of uncooked rice. Elongation is always associated with volume expansion. According to Choudhury (1979), high volume expansion of cooked rice is considered to be good quality by the working class people and very large families who do not care whether the expansion is lengthwise or widthwise. High volume expansion is associated with high amylase (Dipti et al; 2003). Also the swelling behavior of cereal starch is primarily the property of its amylopectin content and amylase acts as diluents and as an inhibitor or swelling especially in the presence of lipid as reported by Morrision (1990).
The widthwise elongation ratio of the varieties ranged between 1.39 and 1.59 with the highest widthwise elongation ratio obtained in IR5. IR5 with widthwise elongation 1.50 which is greater than the standard 1.50 is by every indication desirable according to Juliano, (1972). The values of widthwise elongation ratio of the varieties did not differ significantly at (P>0.05).
The actual elongation is the average length of twenty cooked rice kernel minus average length of twenty uncooked rice kernel. It varied between 0.05 and 1.77 mm (Table 3). IR5 had the highest (1.77mm) actual elongation. Statistically the values of actual were the same at 5% level (P>0.05).
The gelatinization temperature of the varieties did not differ singifcantly at 5% level (P>0.05). It ranged from 76.00 to 79.00oC (Table 3). 305 vareity had the highest gelatinization temperature. All the three varieties had a very high gelatinization temperature. According to Juliano (1993), gelatinization temperature affects the degree of the cooking of rice because of the cooking gradient from the surface to the core of the grains. He further stated that, gelatinization temperature correlates directly with the cooking time as low gelatinization temperature favours fuel conservation. This was true with all the tested varieties having very high gelatinization time between 27.00 and 28.67 minutes which indicates high cooking time and also had a very high gelatinization temperature between 76.0 and 79.00oC. However, high gelatinization temperature could as well be a varietal property and can be hereditary too as stated by Faruq et al., (2003).
The gelatinization time of the three test varieties varied between 27.00 and 28.67 minutes. The highest gelatinization time was recorded in Ir5 followed by Faro5 (28.00 minutes) respectively (Table 3). The least gelatinization temperature was found in 305 (27.00 minutes). According to Heda and Reddy (1986), amylase content determines the texture of cooked rice whereas gelatinization temperature determines the cooking time and the higher the gelatinization temperature the longer the cooking time. Statistically, all the three varieties did not differ significantly (P<0.05) in there gelatinization time.
Table 4 Chemical Composition of Some raw Rice Varieties Selected from Onueke
Chemical composition Faro5 IR5 305 LSD
Fat% 3.50 3.25 1.75
Ash% 2.40 1.40 0.40
Fibre% 0.50 0.75 1.25
Moisture% 9.00 10.00 10.00
Carbohydrate% 82.55c 84.60b 85.43a 15.41
Riboflavin mg/100 0.22 0.26 0.29
Niacim mg/100g 7.25b 9.84a 6.57c 0.12
Calcium mg/100g 3.64 3.25 4.02
7.22 9.81 6.54
Means are duplicate determination. Means not followed by the same letter in each column are significantly different at 5% level (P< 0.05)
4.2 Proximate composition of the Rice Varieties Selected from
The protein content of the varieties ranged between 6.32 and 8.93%with the lowest and the highest found in 305 and IR5 respectively. (Table 4). The nutritional quality of rice depends on the total quality of protein. Rice is an important source of protein and supplies more than 70% of the total protein consumed world wide. On the basis of nutritional value, all the tested varieties contained significantly average amount of protein except one which is below the standard rate 7% reported by Dipti et al, (2003). The result was not low in range of protein content (5.71 to 7.42%) reported by Heinemann et al, (2005) Food composition tables assessed and reported in Heinemann et al, (2005) report protein contents for commercial rice from 7.02% to 8.3%for brown rice and 6.3 to 7.3 for milled rice with small variations in moisture contents (Juliaiw and Bechtel , 1985, Scherz etal,2000, USDA, 2004,USP,2004)
However, many researches mention protein in different varieties of rice up to 15% (Sotelo et al, 1990, Lam-Sanchez et al, 1993, Kennedy and Burlingame, 2003). The improvement of nutrient contents through plant breeding relying on varital differences associated to cultural managements such as water supply handling, fertilizer application and soil Nitrogen availability, would be very interesting when nutritional quality of the product were considered. This increase would be particularly important is in countries where rice is present on every meal. The result of the statistical analysis showed no significant difference between the samples (p>0.05) (Appendix).
The fat of the samples did not differ significantly (P>0.05) among themselves (Appendix) and from 1.757 to 3.50%. Faro 5 had the highest fat content while 305 had the least (Table 4.1). These value were similar to those range 1.46 to 3.22% reported in some food composition tables (Scherzo et al, 2000, USDA, 2004, USP, 2004) and by Julia no (1985)
Ash residue is generally taken as a measure of the mineral content of the original rice sample (ONWUKA, 2005). The result of ash content range between 0.40 and 2.40 % (Table 4). Faro5 had the highest value while the lowest was found in 305 variety. Statistically, the ash content were similar (P>0.05) (Appendix). The ash content of the samples were far higher than the value,1.21 to 1.18% and 0.47 to 0.55% for parboiled brown rice and parboiled milled rice respectively, as reported by Heinemann etal, (2005). High ash content in milled rice is an indication of a good quantity of minerals in the rice. According to Juliano and Bechtel (1985), who compiled data from 22 scientific papers, the ash contents of rice submitted to conventional milling vary from 0.3% to 0.8%. Further comparisons were made with literature data for total ash contents and values around 0.5% were the most common (Sotelo etal, 1990, Scherz etal, 2000, USDA, 2004). Therefore, the mean values for ash in milled rice samples found in the present work meet those in the range of variations previously reported.
The fibre content of the samples ranged from 0.50 to 1.25 as show in Table 4.1.305 sample had the highest fibre content while Faro5 had the lowest. The statistical analysis of the samples showsd no significant difference at 5% level (P>0.05)(Appendix).
Moisture content affects rice quality in many ways to gain and maintain the optimum milling quality, rice must be harvested at proper moisture content and should be dried carefully down to 14%for bag storage and 12% recommended for bulk storage in silos (okaka,2005) all the samples presented average moisture content varying between 9%and 10% within the limit of 14%requested for safe storage of processed rice (brasil,1988)and below 12%recommended for long term storage and to avoid insect infestation and micro organisms development (cogburn,1985).statistically, all the samples are the at 5% level of significance (p>0.05) (appendix).
The carbohydrate (CHO) contents of the samples ranged from 85.55% and faro 5 repectively as show in (Table 4). Carbonhydrate is a source of energy for the synthesis of lipids and proteins (Basha et al., 1976) and decreases in the dry seasons. The statistical analytsis of the samples showed significant difference (p< 0.05) at 5% level. It is therefore indicate that 305 rice sample is significantly the same in CHO content with IR5 and Faro5 when compared with the LSD (15.41) (Appendix 6). The CHO values of the samples were higher than the range 77.6% and 78.5% reported by Sujatha et al. (2004).
The Riboflavin content of the samples ranged between 0.22 and 0.29mg/100g with the highest and lowest values obtained in 305 and Faro 5 respectively (Table 4). The riboflavin values were higher than 0.05mg/100g reported by Okaka (2005). Statistically the values did not show significant difference (p>0.05) at 5% level (Appendix).
The Niacin content of the varieties tested ranged from 6.57 to 9.84mg/100g as shown in( Table 4). Variety R5 had the highest Niacin content while 305 had the least. The results were far higher than the value 4.60mg/100g as reported by Okaka (2005). Statistically, the Niacin values of the varieties were significantly, different at 5% level (p<0.05). It therefore, suggest that IR5 variety is significantly richer in Niacin than Faro 5 and 305 while Faro5 is significantly richer in Niacin than 305(Appendix).
The calcium content of the varieties ranged between 3.25 and 4.02mg/100g with the highest and lowest found in 305 and R5 varieties respectively (Table 4).The statistical analysis of the varieties were similar at 5% level of significance (p>0.05) (Appendix). Although the calcium contents of the varieties were reasonable, it was invariably low when compared to 12.00mg/100g reported by Okaka (2005). It can compare favorably with the value 4.61mg/100g reported by Heinemann etal. ,(2005).
The zinc contents of the varieties did not differ significantly (p>0.05) as shown in Table 4. The results ranged from 6.54 to 9.81mg/100g with the highest and lowest obtained in IR5 and 305 respectively. The values are far higher than 1.15mg/100g for parboiled milled rice reported by Heinemann, etal. , (2005). Milling process did not affect zinc (p>0.05), which display important physiological functions.
This retention could be explained by their uniform distribution inside the grain (Bajaj etal. , 1989). These authors found minor losses of microelements such as Zn, Cu, Fe and Mn, and major losses of macro elements such as P, K, Ca and Mg due to milling, a fact that suggests that microelements seem to be uniformly distributed in the grain , contrasting with the macro elements that seem to be present in external layers, aleurone and pericarp and are therefore more affected by the process . David etal. (2003) also observed significant losses of Zn and Mn in the parboiled milled rice cultivated in the south of Brazil. It is believed that the retention pattern of zinc is the result of the interaction of different factors such as mineral location in the grain and its solubility during soaking, different ratios of migration as well as variations in the hydrothermal process of parboiling and milling resistance of the parboiled grain (Chianaswamy and Bhattacharya, 1983). Further studies should be carried out in order to get a more complete understanding of the mineral retention.
Table 5: Chemical Compositions of Cooked Rice Varieties
Faro5 IRS 305 LSD
Protein% 3.00 2.90 2.50 –
Fat% 1.40 0.80 0.70 –
Ash% 0.61 0.70 0.71 –
Fibre% 2.30 0.90 0.80 –
Moisture% 30.98 30.00 31.47 –
Carbohydrate% 61.70 64.10 63.52 –
Riboflavin mg/100 0.21 0.23 0.26 –
Niacim (mg/100g) 1.33 1.30 1.47 –
Calcium mg/100g 8.33 8.00 9.00 –
8.80a 7.82b 5.52c 0.09
Means in the same column with the same superscript are not significantly different at 5% level (P<0.05).
Chemical Compositions of Cooked Rice Varieties
Rice is the most important cereal for human consumption and must be cooked before eaten or consumed. Rice is cooked by washing and boiling in water which leads to loss of some nutrients (Ihekeronye and Ngoddy, 1985; Perez et al, 1987).
The protein content of cooked rice samples ranged from 2.80% in 305 to 3.00% in Faro5 (Table 5). The protein levels in cooked Faro5, IR5 and 305 rice were not significantly (P>0.05) different
The fat content of cooked rice ranged between 0.70 and 1.40% with the highest and lowest obtained in Faro5 and IR5 respectively. The fat content of the samples were not significantly (P>0.05) different
The ash contents of cooked IR5, Faro5 and 305 rice ranged from 0.61 (Faro5) to 0.71 (305). It did not differ significantly at (P>0.05).
The fibre contents of the cooked IR5, 305 and Faro5 rice ranged from 0.80% in 305 to 2.30 in Faro5. The fibre levels of cooked IR5, 305 and Faro5 rice were significantly (P<0.05) different.
The moisture content of cooked IR5, 305 and Faro5 ranged from 30.60 to 31.47%. 305 had the highest moisture content (31.47%), followed by Faro5 (30. 98%) while IR5 showed the lowest moisture content (30.66%) in cooking. It showed no significant (P>0.05) difference.
The carbohydrate (CHO) content ranged between 61.70 and 64.10% with highest and lowest obtained in IR5 and Faro5 respectively. The CHO of cooked IR5, Faro5 and 305 were not significantly (P>0.05) different.
The riboflavin levels of cooked samples did not differ significantly (P>0.05). it ranged from 0.21 to 0.26mg/100g. 305 had the highest riboflavin while the lowest riboflavin was found in Faro5.
The Niacin levels of the cooked varieties ranged between 1.30 and 1.47mg/100g with the highest and lowest Niacin recorded in 305 and IR5 respectively. It showed no significant difference (P>0.05).
The calcium contents of the cooked rice varieties ranged from 8.00 to 9.00mg/100g. 305 variety had the highest calcium (9.00mg/100g) while IR5 variety had the lowest calcium (8.00mg/100g). There was no significant difference (P>0.05) between the samples in the calcium levels.
The zinc contents of the cooked rice varieties range between 5.52 and 8.80mg/100g. Faro5 variety had the highest zinc (8.80mg/100g), followed by IR5 (7.82mg/100g) while 305 had the lowest zinc (5.52mg/100g) content. The zinc levels of the cooked rice varieties were significantly (P<0.05) different.
Table 6: Nutrient compositions of Raw and Cooked rice varieties
Nutrient Composition Raw Rice Cooked Rice
Faro5 IR5 305 Faro5 IR5 305 LSD
Moisture (%) 9.00d 10.00d 10.00d 30.98b 30.60c 31.47a 1.19
Ash (%) 2.40 1.40 0.40 0.61 0.70 0.71 –
Fat (%) 3.50 3.25 1.75 1.40 0.80 0.70 –
Crude Fibre (%) 0.50d 0.75d 1.25c 2.30a 0.90b 0.80b 1.05
Protein (%) 8.23b 8.93a 6.32b 3.009c 2.90b 2.80d 3.33
Carbohydrate (%) 82.55c 84.60b 85.43b 61.70b 64.10ab 63.52b 11.84
Riboflavin (mg/100g) 0.22 0.26 0.29 0.21 0.23 0.26 –
Niacin (mg/100g) 7.25b 9.84a 6.57c 1.33d 1.30d 1.47d 0.38
Calcium (mg/100g) 3.64d 3.25d 4.02c 8.33b 8.00a 9.00b 6.41
7.22c 9.81a 6.54d 8.80b 7.82c 5.52d 0.62
Nutrient Composition of Raw and Cooked Rice Varieties
The nutrient composition of raw and cooked 305, IR5 and Faro5 varieties are shown in Table 6
The three rice varieties, Faro5, IR5 and 305 contain high carbohydrate contents in raw while low in cooked rice. The carbohydrate contents in these rice varieties were affected by cooking. This was contrary to the work of Osaretin and Abosde (2007) whose opinioned, that carbohydrate contents of rice varieties were not affected by cooking, or when soaked in water. Rice is a good source of energy since it is rich is carbohydrate. The complex carbohydrate in rice digests slowly allowing the body to utilize the energy released over along period which is nutritionally efficient. The drastic reduction in carbohydrate was not expected or anticipated and may be due to analytical procedures. The protein contents of the varieties were low in cooked rice when compared to values 6.32 – 8.93% for raw and 3.5 – 4.29% for cooked rice varieties reported in literature by Osaretin and Abosede (2007).
Sujatba et al, (2004) reported a protein range of between 5.18 and 10.40% Okaka (2005) also reported a protein range of 6.8 – 8.0 mg/100g. Reduction of protein contents was expected after cooking. This was in agreement with the work of Osaretin and Abosede (2007) who reported that the protein contents of rice varieties were affected by cooking and soaking in water. He further said that, cooking of rice denatures the protein, which resulted in its reduction. He explained further that, there was a slight reduction in the protein level of both rice varieties when soaked in water due to solubility of some proteins. The three rice tested were expected to show similar characteristics or properties during cooking which they showed.
The fat contents of the three rice varieties were low and were affected by cooking. The varieties showed a drastic reduction in fat level. The varieties; Faro5, IR5 and 305 showed 2 times, 4 times and 2 times reduction of their original fat contents respectively. This drastic decrease or reduction in fat contents was contrary to the report provided by Osaretin and Abosede (2007) who reported that fat content of both rice varieties tested by them were low and were not affected by cooking and soaking in water.
However, the 305 rice contained more fibre in raw rice than IR5 and Faro5 while Faro5 contained more fibre in cooked rice than IR5 and 305. These variations and differences in the fibre content may be attributed to post-harvest processing techniques while inconsistency in the result may be due to analytical method or the way the fibre content was analyzed. Dietary fibre results in reduction of risk of bowel disorders and fights constipation (Champe and Harrey, 1994).
The 305 rice contains more water than Faro5 and IR5 rice at raw and cooked states. 305 rice requires less time to cook or gel and hence consumes lesser electricity units and energy. This finding is in agreement with Abulude (2004) and Sanni et al (2005). It also follows that the Faro5 rice variety may have a longer shelf life compared to 305 and IR5 rice due to the lower moisture content. All the three rice varieties showed high absorption of moisture. The moisture increase was three times their original moisture level which was quite expected.
The result of the present study show that cooking did significantly affect the mineral content of the three rice varieties; 305, Faro5 and IR5 varieites. The three rice varieties contain useful quantities of calcium and zinc. These observations support previous reports (TFCT, 1999) and work of Osaretin and Abosede (2007). All the varieties are good sources of minerals which will contribute to the recommended dietary allowance (Heinemann et al., 2005). Minerals are constituents of the bone, teeth, soft tissue, muscle, blood and nerve cells. They are vital for overall metal and physical well-being. Minerals act as a co-factors for many biological reactions within the body, including muscle contraction, neuro-transmission, production of hormones, digestion and utilization of nutrients (Champe and Harvey, 1994).
There was an increase in all the calcium contents of the three varieties after cooking. These may be due to the presence of calcium in the cooked water. This increase in calcium content after cooking was contrary to the work of Osaretin and Abosede (2007) which reported a decrease in calcium content and other minerals like Mg, P and Fe after cooking. The zinc contents of all the varieties decreased after cooking except for Faro5 which increased instead of decreasing as expected.
Data of the present study indicate that 305 rice variety was preferred to Faro5 and IR5 rice. It is suggested that the preferred acceptance of 305 rice could be due to its physical characteristics and superior cooking attributes, in terms of cooking or gelation time and gelatinization temperature.
The vitamin contents of the varieties were high. The varieties are good sources of vitamins. The highest riboflavin was found in raw 305 rice (0.29 mg/100g) while the least (0.22mg/100g) was found in Faro5. There was a significant decrease in riboflavin content of all the rice varieties after cooking. The niacin contents of the rice varieties were also high. A drastic reduction was observed in niacin levels of the rice varieties after cooking.
Cooking of these rice varieties significantly resulted in nutrients depletion, especially in niacin, CHO, fat and riboflavin. These losses in nutrients may be due to anti-nutritive factors, extraction and leaching effects of water (Perez et al, 1987: Bhattacharya and Ali, 1986; Adeyemi et al, 1986; Adeyeye and Ajewole, 1992). However, differences in soil chemistry environmental factors, storage, transportation and processing methods may contribute to variations in the physical characteristics, nutrients composition and sensory attributes of the rice varieties tested.
Ash content indicates the degree of mineral matter in the rice sample. Faro5 contains high ash content in raw rice more than 305 and IR5 and was lowest in ash content after cooking. Both Faro5 and IR5 decreased in ash content due to cooking while 305 increased in ash content after cooking. This increase in ash content of cooked 305 may be attributed to analytical procedures or calculations.
The cooked 305, IR5 and Faro5 rice varieties were significantly (P<0.05) high in moisture contents than their raw rice counterparts. The cooked 305, IR5 and Faro5 rice varieties did not differ significantly from each other in M.C when compared with the LSD (1.19). Also their raw moisture content did not differ significantly from each other when compared with the LSD (1.19).
The raw and cooked 305, IR5 and Faro5 rice varieties showed no significant change (P>0.05) in their ash, fat and riboflavin levels.
This simply means that the ash, fat and riboflavin levels were not significantly different in both raw and cooked 305, Faro5 and IR5 rice varieties.
The protein contents of the raw and cooked Faro5 and IR5 rice were significantly high as compared to 305 rice.
The niacin levels of raw 305, IR5 and Faro5 rice were significantly (P<0.05) different from their cooked 305, IR5 and Faro5 counterparts. The raw 305, IR5 and Faro5 rice varieties differed significantly from each other when compared with the LSD (0.38).
The zinc and calcium ions levels in the raw and cooked 305, Faro5 and IR5 were significantly (P<0.05) different. The raw IR5 was significantly higher in zinc more than raw and cooked 305 and Faro5 while 305 was significantly lower in zinc than IR5 and Faro5 in both raw and cooked rice. The cooked 305, Faro5 and IR5 rice varieties were significantly higher in calcium than their raw rice counterparts.
The raw rice varieties did not differe significantly from each other in calcium when compared with LSD (6.41). Also, the cooked rice varieties showed no significant difference from each other when compared with the LSD (1.05).
The carbohydrate content of the raw and cooked 305, IR5 and Faro5 rice varieties were significantly (P<0.05) different. However, when compared with the LSD (11.84) value, the raw varieties showed no significant difference from each other as well as the cooked rice varieties.
The raw and cooked 305, Faro5 and IR5 rice varieties were significantly (P<0.05) different in their fibre contents. The cooked Faro5 rice variety was significantly higher in fibre level than the raw Faro5, 305 and IR5 rice. The cooked varieties showed no significant difference among each other as well as the raw rice varieties. The Faro5 of raw and cooked rice variety was significantly lower in fibre than 305 and IR5 rice varieties.
Table 7 Functional properties of rice varieties selected in Onueke
Faro5 IR5 305 LSD
Bulk density 0.82a 0.85a 0.84a –
Swelling capacity 378.33a 281.67c 311.67b 26.08
Water Absorption 7.70b 8.15a 7.55b 0.18
Mean varieties in the same row with the same letter did not differ significantly at 5% (P > 0.05).
Functional properties of rice varieties selected in Onueke
The bulk density is the mass per unit volume of a substance (rice) . It is a function of both temperature and pressure. It is equally the measure of weight and volume through which a given quantity of rice can occupy. The bulk densities of the varieties ranged from 0-.82g/ml to 0.85g/ml with the highest and lowest obtained in IR5 and Faro5 rice respectively. The varieties showed mo significant (p>o.o5) difference in their bulk densities. The results agrees with the range 0.77g/ml to 0.88g/ml reported Narpinder et al, (2005).
The swelling capacity is the ratio of the final weight or volume of cooked rice to the initial weight or volume. It gives an indication as to know well the grain will swell when cooked (Adeyemi , 2006)
It ranged between 281.67 and 378. 33 with the highest obtained in Faro 5 (378.33) followed by 305 (311.67). The swelling capacity were significantly (p<0.o5) different.
The variety Faro 5 is significantly higher in swelling capacity than the other two varieties. Also 305 varieties is significantly higher in swelling capacity than IR5 variety.
Water absorption capacity refers to the amount of water absorbed by the grain when cooked for any length of time or to eating consistency (Adeyemi , 2006). Increase in weight is a measure of water absorption. It ranged from 7.55ml/g to 8.15ml/g with the highest and lowest found in IR5 rice and 305 rice respectively. It showed significant (p<o.o5) difference at 5% level. When compared with the L S D (0.18), IR5 differed significantly with 305 and Faro 5 while 305 and Faro 5 are the same (did not show significant difference) IR5 is significantly higher in WAC than Faro 5 and 305 while Faro 5 and 305 are significantly the same in WAC.
Table 8: Sensory attributes of cooked rice
Appearance Colour Flavour Taste Texture General Acceptability
Faro5 7.00b 7.50b 7.10 7.20b 6.95 7.45
IR5 7.30b 7.85b 6.90 7.55b 7.35 7.15
305 7.95a 8.60a 6.95 8.20a 7.25 7.10
0.55 0.55 – 0.62 – –
Values in the same column with the same superscript are not significantly different (P<0.05).
Mean Scores for Quality Attributes of Cooked Rice Samples
The mean scores for quality attributes of cooked rice varieties are shown in Table8. The results show that there was no significant difference for flavor, texture and general acceptability of the samples among the treatments or varieties.
305 varieties was the most preferred variety by the sensory panelist with respect to all quality attributes except flavor texture and general acceptability. The general/overall acceptability of Faro5 was the most preferred. The decrease in general acceptability in IR5 and 305 may be due to the cooking condiments cooking techniques and stirring. 305 was significantly different from IR5 and Faro5 in appearance, colour and taste whereas there was no significant difference between them in other quality attributes. In terms of appearance, colour and taste, there was no significant difference in Faro5 and IR5 varieties. Faro5 and IR5 were similar in all quality attributes. With regards to taste, 305 received the highest scored followed by IR5. Faro5 and IR5 received the lowest mean scores for almost all quality attributes. It is possible that the panelists are more familiar with condiments used in cooking 305 variety than IR5 and Faro5 respectively. Conclusively, the results of sensory evaluation or analysis of the varieties simply suggest that variety 305 is better preferred by the panelist than the other two varieties IR5 and Faro5.
CONCLUSION AND RECOMMENDATION
The present study revealed a high nutrient content in all the varieties tested especially in protein, Niacin, calcium, zinc, riboflavin ash and CHO. Nutrient depletion occurs in all the varieties during cooking except in Fibre, calcium and Zinc. There are no significant differences in the chemical composition of raw rice varieties except for carbohydrate and Niacin, chemical composition of cooked rice varieties except for fibre and zinc, physical properties of raw rice varieties except for L/W ratio, physical properties of cooked rice varieties except for length and sensory attributes of the three varieties except for appearance, colour and taste and are affected by processing methods.
The study also depicts that Onueke rice varieties show differences in their physical properties, chemical composition, function and cooking properties and such can compete with its foreign rice counterparts in the world market.
At the end this of research work, rice is recommended to people for consumption because it is a good source of carbohydrate for energy, though is not consumed raw, it has to be cooked. Also it has appreciable amount of protein coupled with the condiments use in preparation of cooked rice which will help to improve the nutritional value of cooked rice.
Rice Produce Within The Rice Producing Area, Onueke, Ebonyi State, Nigeria
To place an order for the Complete Project Material, pay N5,000 to
Account Name – Chudi-Oji Chukwuka
Account No – 0044157183
Then text the name of the Project topic, email address and your names to 08060565721.