Rice Storage – Different Stages Involved, Effect On Quality Of Milled Rice

Rice Storage – Different Stages Involved, Effect On Quality Of Milled Rice

Rice Storage – Different Stages Involved, Effect On Quality Of Milled Rice

Rice (Oryza Sativa) is the most important cereal crop in the developing world and is the staple food of over half of the world’s population.

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It is Known as a semi-aquatic annual grass plants, and obtaining both high yield and high quality rice is becoming more and more important. Traditional plant breeders have focused on producing rice varieties that achieve higher yields with greater pest resistance. These approaches ensured that countries were able to produce sufficient rice to meet basic food demand. As countries reach self-sufficiency in rice production and are capable of meeting basic food requirement, the trend is to incorporate preferred quality characteristics that satisfy the consumers increasing demand for better rice of superior quality Rice like other cereal grains is subject to deterioration because of change in temperature and relative humility. The term storage is not always easy to define although according to oxford advanced learner’s Dictionary, the term storage is defined as a process of keeping something in a particular place until it is needed and used, during storage determines its longevity.

Rice grain after harvest are usually stored for the next harvest season for home consumption (Pusa Pamma and Vimala, 2000). After harvest, correct storage of the grain is important to prevent mould spoilage, pest infestation and grain germination of dry rice which held for only few months, minimum nutritional changes will take place but if the rice grains are held with a higher amount of moisture, the grains quality can deteriorate because of starch Degradation by rice grain and Microbial amylase (Brigid 2004).

There are many forms in which rice may be stored and the variations in degree of susceptibility of those forms to the biological factors which are responsible for some types of deterioration During storage, this makes it one of the most complex of all cereal grains, since rice is consumed as a whole grain, so that the presence of organisms result to loss in weight and quality.



Therefore the aim/objectives of this work is to review the different stages involved in rice storage and its effect on quality of milled rice.



Storage of rice is a normal step between harvest and consumption. Storage conditions (Temperature, time and moisture) may differ significantly.

Rice storage is required to change certain physiochemical properties of the rice, such as stickiness from a sticky to a relatively non sticky product after cooking (Baharaya K.R Sowbhagy, CM 1971).

Change in physiochemical and quality factors of rice grains that occur during post harvest storage, influence the chemical physical and functional properties of rice. Charstil J, W.E marashell and J.I. Wadsworth, eds) marcle Dekker New York. (1994).

Storage induce aging have both desire and undesirable effect in the end product, depending on storage conditions and the type of rice varieties.

Aging changes are the result of the physiochemical interactions among rice components and enzyme reaction involving protein, starch and lipid.

Generally, the outer (aleuroue) layers of the rice grains are more susceptible to these changes than the inner (endosperms) layers. Storage why Starts in the field during of the storage of paddy. (change, 2000) many of the physiochemical and functional change that occurs during storage, such as swelling, water up take by cooking, cooking time stickiness after cooking are all caused by protein starch interaction, other change due to aging are not yet fully understood. (Hamaker, 1993) storage induced change in the physiochemical properties of rice; it may be both desirable and undesirable depending and the storage condition, variety and end user requirements. Moisture content storage temperature and storage time are the factors most influential of the chemical, physical and functional qualities of rice during post harvest storage.


Of the minor components, the phenolic acids are of particular interest because of their involvement in plant cell walls. Of course, intense interest in the compounds is also related to their physiological activity and potential dietary uses. It is this role that is currently driving research in this area. Grains are characterized by various phenolic acids and particularly hydroxyainamic acids. Among them, ferulic acid (FA) and p-Coumaric acid (PCA) are the main phenolic acids present in the cell wall of monocots and especially of Gramineae. Sasulski et al reported that FA constituted more than 90% of the total phenolic acids in wheat flour. Data are also available on the concentration of ferulic acid in rice. Data reported for rice endosperm cell walls 12g kg-1 esterifies cinnamic acids comprising 9gkg1 FA, 2.5g kg-1

PCA and 0.5g kg-1 diferulic esters. However, ferulates and diferulates are never fully released by any solvolytic method are always underestimated.

The phonolic acids are usually concentrated in the outer aleurone layer of the seed, which is rich in arobinoxylans. A portion of the total cinnamate exists as ferulate diners linked in various ways including the historically quantified 0-[5-0-(trans-feruloyl)-al-arabinofuranosy 1]-(1-3)-0.B-D-xylopyransoyl-(1-4)-0-xylopyra-nose. Cinnamates and particularly FA are introduced into cell wall matrices attached to polysaccharides. Thus, FA becomes etherified no arabinose residues in primary cell wall arabinoxylan matrices. The attachment involves a covalent ester linkage-between the carboxyl ate group of FA and the primary alcohol on the c-5 carbon of arabinosyl side chains attached to a xylan backbone. The formation of ferulate divers facilitates covalent coupling of the polysaccharides by radical mediated dimension. As the wall signifies, ferulates and diferulates become involved in radical cross-linking reactions with lignin monomers to intimately incorporate the ferulates into lignin.

The phenolic compounds exert a significant effect on the properties of the cell wall which is mechanically strengthened by the cross-linking. The content of free phenolic acids increased during storage of milled rice. Tsugita et al, suggested the bound phenolic acids were released by enzymatic and non-enzymatic reaction and these were large increases in the concentration of p-hydroxybenzoic acid, vanillic acid, syringes acid, caffeic acid, PCA and FA when rice was stored at 400c (80% RH) for 60 days compared with storage at 40c. They considered that the change in the concentration of phenolic acids contributed partly to the change of cooking properties of aged rice. The change in the ferulic acid concentration was useful in predicting the end-use quality of grains.


There are several changes that occur during storage of rice product these changes are.


Attempts to explain the changes in functionality associated with ageing have focused on the properties of rice components, such as starch, protein & lipids and the interactions between them during storage. As with functionality, changes in starch, lipid and protein components were most apparent at an elevated storage temperature although gross changes in starch, amylase & protein content of the rice grain during storage were minimal. However, the alkali liability number( alkali soluble components) of both waxy and non-waxy rice increase during storage up to 7 years indicative of some degree of de-polymerization of the starch. Villareal R.M resurrection, A p Suzuki 9b. S. Jouliano L.B.O. (1976)


Storage induced changes in the physicochemical properties of rice may be both desirable and undesirable depending on storage conditions, variety, and end user requirements, moisture content, storage temperature and storage time are the factors most influential on the chemical, physical and functional qualities of rice during post harvest storage. The rate and nature of the change is primarily temperature dependent. Quality generally occurs faster with increasing temperature and moisture content. Conversely under experimental conditions, favorable rice quality has been preserved for years at sub-zero temperature. In the United States storage temperature, moisture content and storage time varies between 50 and 95 f, 10 and 15%, and 2 and 24 months respectively.

Rice quality shift begin during filed drying and continue after harvest changes in rice quality as a result of aging are due in large part to enzymatic reactions involving protein, starch, and lipid. Generally the outer layers are more susceptible to these reactions than the endosperm of the rice kernel. Although the physiochemical properties of brown rice may exhibit greater change milled characteristic can also be altered during storage.


Reducing sugar (Maltose) increase and non-reducing sugar (sucrose) decrease during storage. The degradation of carbohydrate to Co2 is usually very small, but it may become significant at moisture content >14% (12, 14,15).The change in free carbohydrate content are greatly influenced by temperature and browning reaction free carbohydrate and free amino acids may play a significant role in Co2 formation Non- reducing carbohydrate , free fatty acids and germination, Activity are closely related (Adam, 1976) Reducing sugars increase (sucrose) decrease during storage when subjected to temperature of 77f (25oC) or greater similarly total starch content does not change appreciably during storage, although small changes in starch properties have been observed.


Starch in rice grain concentrated mainly in the endosperm. Total starch content does not change significantly during storage. However some small changes in starch properties have been noticed which include the change in, molecular –weight of starch and its components (amylose and amyl pectin) although small may be significant (Hamaker 1993).

Content does not change appreciably during storage although small change in starch properties have been observed. Changes in the molecular weights of starch and its components (amylase and amyl pectin) may be significant albeit small. Enzymes, such as amylases, initiate starch synthesis and degradation processes in the rice grain during storage. Major changes in hardness, gel consistency and viscosity values require approximately three months. Therefore, textural evaluation should be alone on samples aged at least three months. The greatest textural changes would be expected in high amylose varieties. Cold storage preserves cohesiveness, a desired trait in Japan Julinano, B. O onate and Delumndo A.M (1965)



Research demonstrated that protein content, texture, tenderness and cohesive of cooked rice are concentrate in the outer layers of the kernel but significant amount are also present in the endosperm. During storage the protein interact with starch diminishes there by altering the texture of the rice due to change in water diffusion properties and gelatinization and converts slowly to fermentable sugars (Juliano, 1993).

Protein content affects texture, tenderness, and cohesiveness of cooked rice protein are most concentrated in the outer layers of the rice kernel but significant amounts are also present in the endosperm total protein close not change considerably during storage, however, the chemical properties of the protein can be altered substantially eighty to 90% of the storage protein in rice is oryzenin (Glutelin).

After one year of storage at w40f (40c) the molecular weight of oryzenin doubled in both medium and long grain varieties. Small changes in the ration of oryzenin to other protein were also observed especially where a marked decrease in free amino acid content was apparent. Free amino acids related to non-enzymatic color changes in stored rice and where influenced by temperature and moisture content.

One mechanism by which protein influence texture is hypothesized to involve the regulation of water diffusion into the starch granule and which consequently outers the water and time requirements for cooking secondly, protein may impede starch gelatinization. It has been suggested that starch granule associated protein confer strength to the gelatinized granule reducing the leaching of amylase molecules or by physically holding the starch granule together. Thus, during storage the interaction of protein with starch diminished thereby altering texture due to change in water diffusion properties and gelatinization processes during cooking, the brewing industry is reluctant to use rice storage stored for long periods because it requires higher temperatures for gelatinization and convert slowly to fermentable sugars.

Rice textural properties change significantly in the months following harvest. Many of the functional changes that occur during storage that influence cooking properties, such as cooking time, water uptake and stickiness are caused by protein-starch interactions. The oryzenin and starch and/or its components (e.g. amylase). Cooking time increased and after cooking stickiness decreased during storage of both brown and milled rice especially at high temperature.


Pushpamma and Uma reddy (1979) reported that the cooking properties of rice improved after three months of storage. The swelling capacity increased and the amylose content of rice remained constant. Storage decreased the amylose dispersion, which is responsible for greater absorption and retention of water and thus expansion of rice grain. In legumes, storage under unfavorable conditions is know to adversely affect legume cooking quality leading to hard to cook defect that result in both chemical and enzymatic changes. (Viamala, 1982)

Uma reddy (1981) observed that the cooking quality of legume deteriorated or storage, it took a longer time to cook absorbed less water during soaking and gave a lower yield after cooking.


Amylose content is considered the single most important characteristic for predicting rice cooking and processing behaviour. Amylose content is directly related to water absorption, volume expansion, fluffiness, and reparability of cooked grains. It is inversely related to cohesiveness, tenderness, and glassines. The amylose acts as both a diluents and an inhibitor of swelling, especially in the present of lipid.

Bhattacharya et al 1975. Reported the importance of percentage insoluble amylose at 100oc, as a determination of rice quality.

Cooking loss and insoluble amylase content in the cooking water of rice samples have been used to assess quality. The soluble amylase method was statistically more precise and efficient in indicating difference in the working quality of rice. The amount of leached amylase, which depend on the total amylase content of the rice, correlated positively with the texture of cooked rice, which possesses total amylase contents in the range 18.4-29.5%. It was suggested that the leached starch content resulted in a similar correlation between the setback value (as measured by amylography) another texture of the cooked rice. However, gelatinization temperature from OSC were not correlated with the texture of the cooked rice. Based on the results it was hypothesized that the longest amyl pectin chains interacted with other rice components, and that the resultant complete were retained in the cooked grain where they inhibited softening. A reduction in the amount of extractable solid for aged rice was reported by villa real et al although shibuya et al found an opposite effect the amount of amylase from 45- mesh flour that was soluble in boiling-water decreased during rice storage. These results probably affect the increase in water-insolubility of rice starch and protein during ageing, resulting in a slower rate of cooking.

Although there is minimal change in gross chemical composition of the rice grain during storage some hydrolysis or degradation probably occurs leaching to a significant proportional increase in reducing sugar and a decrease in reducing sugar and a decrease in non-reducing sugar and starch. These are few, if any, reports on the ageing-induced structural changes in the starch molecules (amylose and amylopectin). This may be due to low sensitivity of analytical methods and the high concentration of starch in rice grains plus the large size of the starch molecules.


The odour and flavour of cooked rice changed with time even when stored in under air tight condition (Barher, 1972). Aldehydes and what were identified as the dominant source of the off flavors although other undesirable compounds were also detected e.g. hydrogen surphide. Most of the detected volatile compounds were products of lipid amino acid or vitamin decomposition, well-polished rice (12%) retained it flavour for a longer period than under polished rice, this was expected because the outer layer of the kernel contain the highest levels of oxidizable compounds that contribute to off flavors. Billing H; Hampeli, G and El-baya Riso 26 (1977)


The odor and flavour of cooked rice changed with time even when stored in under airtight condition. Aldehydes and ketrones were identified as the dominant source of the off flavors although other undesirable compounds were also detected (e.g. Sulphurdioxide, hydrogen sulfide). Most of the detected volatile compounds were products of Lipid, amino acid and/or vitamin decomposition.

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Well polished rice (12%) retained its flavour for a longer period than did under polished rice. This was expected because the outer layers of the kernel contain the highest levels of oxidizable compounds that contribute to off flavors.

Taste is an expression of intrinsic characteristic of the rice as influenced by the interaction of seed physiological process with the ambient environment. Seed temperature optimal ranges for mc is 7 to 14%. Moisture content below 7% can reduce seed viability. Note that the relative humidity increases with decreasing temperatures, therefore the equilibrium moisture content can change with temperature.

. However the compound,2-acetyl-1pyrroline has usually been identified as the most important volatile constituent contributing to the aroma in serial aromatic rice varieties. Propanoal, pentanal and hexane were reported to be the major carbonyl compounds that increase the most during storage. Formation of carbonyl compounds is attributed to oxidation of unsaturated fatty acids. Other compounds that increased during storage were butan-1-ol, 2 methylpropanl (isobutyraldehyde) and 3-methylbutanal (isovaleraldehyde). Nevertheless, hexane is considered the major stale flavor constituent of cooked rice as it more than doubled during storage of 60-70 days. Waxy rice tends to have higher carbonyl content than non-waxy rice. Due to its higher content of non-starch lipids in the endosperm.


Taste is an expression of intrinsic characteristics of the rice as influenced by the interaction of seed physiological processes with the ambient environment accordingly taste is very sensitive to the storage conditions, such as temperature and the associated compilation of effects on other metabolic functions. (Damels, 1998).

Changes are minimized by low storage temperature and are enhanced by length of storage time (Daniel, 1998).


Cereals or rice consist of phosphates and sulphates of potassium magnesium and calcium. Other important minor mineral elements include zinc, iron & manganese, which may exist in bio-unavailable forms as phytates or oxalates. The content of mineral matter in the husk of rice is higher than that found in the kernel and the ash particularly rich in silica.

A cereal grain is rich in B-group of vitamins and in minerals but distribution of each vitamin in the different parts of the different cereals varies considerably.


The chemical composition of the rice grain varies considerably depending upon the genetic factor of plant variety and upon such environment influence as location and season in which grown, degree of milling and conditions of storage on the average. However, a sampled of milled rice grain will contain about 80% protein 0.5 ash and 11% water.


Lipids in rice are concentrated in the bran, germ and polish fractions. In the tropics, however, oil recovery from rice for food use is hardly practiced like other cereals, rice is lacking in vitamins A, D and C. It owes contain small amount of thiamine, riboflavin and niacin. The levels of vitamin are considerably higher in brown rice than in polished rice, because the B-Complex vitamins are concentrated largely in the bran and germ which are removed by milling. Ocker, H. D. Boiling. H. El-Baya; Riso (1976).

Most of the Lipids in rice grains are concentrated in the outer layers. The endosperm contains only a fraction of the total Lipid content. Lipolytic enzymes (or Lipases) catalyzed the hydrolysis of kernel Lipids (oil). These enzymes are both endogenous and microbial origin. Lipases and Lipids are compartmentalized in the testa a layer and the aleurone and germ, respectively. Therefore these reactions occur principally in the outer layer of the rice kennel where Lipids are concentrated dehulling rice disrupts these outer layers, Lipids diffuse and make contact with the Lipases and hydrolysis of Lipids to fatty acid begins. Microbial produced lipases located on the kernel surface also come in contact with kennel lipids. Deka S.C Sood D.R & Gupta (2000).

The rate of free fatty acid formation in brown rice depends on the degree of surface disruption, moistures content, microbial levels, and temperature of the grain mass.

Approximately 30% of the kernel oil content can be converted to fatty acids within a week under high humidity and temperature. The lipids hydrolyze or oxidize to fatty acids or peroxides during aging. High temperature accelerates Lipid oxidation. Fatty acids are in turned oxidized to an array of secondary metabolic compounds. This causes increased acidity and a deterioration of taste and the production of rancid odours. It is oxidation of fatty acids that contributes to off-odours and taste associated with “spoiled”. The deterioration of brown rice during storage is very fast because of the large amount of Lipids and Lipolytic enzyme present in the bran. Yasumatus K. and moritaka S.S Agric Bio chem.. 28 (1964)

Oxidation, hydro peroxides formed during this reaction yield subsequent products that produce undesirable odours and flavors.


The alpha-amylase and beta-amylase activities of rough rice sample decreased significantly during storage. These changes paralleled the decrease in soluble protein in the grain. Alpha-amylase is concentrated in the bran fraction. Hence, the alpha-amylase content of milled rice is low and has a negligible effect on the amylogram, expect in the case of waxy milled rice, which contains appreciable amount of alpha-amylase in the endosperm and exhibits a lower amylograph viscosity. Peroxides and catalyses activities were lost rapidly during storage of rice. As these are easily measured, they are used as good indices of quality deterioration of rice grains during storage. In Japan, Ohaliwal et al (1997) reported that stored samples had increased activities of proteases, lipases and lipoxygenase.


One of the most sensitive indices of the ageing process in rice is the change in pasting properties, as measured by thermoviscometry and particularly amylography. Rice exhibits very wide ranges of cooking quality and rheological properties that are largely determined by the swelling, gelatinization and retrogradation characteristics of its starch. The viscosity of rice paste increased dramatically after storage of milled rice. These changes depended on storage temperature and duration. For instance, starch isolated from freshly harvested rice for both waxy and non-waxy samples and stored at 29oc for 6 months gave harder gels and higher viscosity than those of starches stored at 20c. However, the amyl graph viscosity of pastes prepared from starch stored at both temperatures was higher than that of the corresponding fresh starch.

In other studies, viscosity increased at higher storage temperature during the first three months of storage and then plateau.

Contradictory data have been reported on the effect of ageing an amyl graph peak viscosity amyl graph peak viscosity of slurries prepared from aged rice was lower than that from fresh rice, although the opposite effect was reported by (Villarreal et al (1976). After an initial increase in amylograph peak viscosity and setback during the first 6 months of storage, a steady decrease was noted during the subsequent 3 years of storage or rough and milled rice. The peak viscosity of slurries made from medium grain rice show a 30-50% increase during the first 3 months of storage for rice stored at 20 and 370c at all moisture content level. A similar trend was observed in the final viscosity. There was no difference in surface structure as seen by scanning electron microscopic (SEM) or in gelatinization characteristics measured by photopastegrams characteristics measured by photopastegrams for starch prepared from Japanese rice stored at 230c and at 40c.

A distinction has been made between the ageing of rice flour and rice starch. Thus shibuyu et al (1977) showed that the pasting properties of fresh and aged rice flour were different but that the properties of corresponding starches did not differ. They also reported that the cell structure was decomposed by endoxylanase during storage which led to the change in amylograms of rice flours. More recently, rapid microanalysis has been adopted as the AACC approved method of rice quality assay. The increase in peak viscosity shows that the starch granules of stored rice are more resistant to swelling than those of fresh rice. The decrease in breakdown value indicates that the capacity of the starch granules to rupture after cooking is reduced significantly by ageing of the granules.

Differential scanning calorimetric (DSC), has provided valuable insights into order-disorder phenomena of granular starches. The gelatinization of rice flour occurred at temperatures from 73 to 860c, with an enthalpy of 8.3 to 9.7,g-1, but what significantly affected by storage, thus, both enthalpies temperature of gelatinization and retogratation of rice flour were affected (p<0.05) by rough rice cultivar, storage temperature, moisture content and duration. Rice stored at 380c exhibited higher gelatinization enthalpies and temperatures than those stored at 40c or 210c. retrogradation enthalpy was increased significantly (p<0.0001) by storage of rough rice, by the peak temperature of the retrogradation endoderm was unaffected. Recrystalization during for 0-15 days was significantly suppressed by cross-linking in non-waxy rice starch. The restricted swelling and reduced hydration instarch granules resulting from the cross-linking delayed gelatinization and retrogradation.

Rice amyl pectin system generally showed two stages of retro gradation behaviour during short (less than or equal to 7 days) and longer( greater than or equal to 7 days) storage. The enthalpy value for late and infinite retrogradation stages showed significantly positive correlations with the proportions of short chain(chain length (CL) less than or equal to 15 glucose units) and long chain (CL=16-100 glucose units) fractions, well respectively.

A weak endotherm at 470c to 660c in the OSC thermo grams was attributed to the denaturizing of oryzenin (rice storage protein-glutelin). Addition of the latter to isolated starch resulted in pasting behaviour that closely resembled aged flour. The denaturation endotherm shifted to higher temperatures with increasing storage temperature time and was no longer detectable after the flour had been stored at 450c for 8 weeks ageing did not affect the gelatinization (as measured by pulsed nuclear magnetic resonance spectrometry, NMR) of either the flour or isolated starch. It was concluded that modification of the protein component rather than starch was primarily responsible for theological changes associated with ageing or rice flour. Cell wall affects are also involved.


Cooked rice texture has been shown to govern the acceptance of rice by consumers when consumed as the whole grain. Texture has been defined as a multidimensional characteristic that only humans can perceive, defend, and measure. This sensory evaluation is critical although instrumental measurement of textural properties is also common practice. For instance the Ottawa extrusion cell has been used for predicting cooked rice texture in conjunction with a miniature extrusion cell and a novel data analysis method called Spectral Stress Analysis (SSA). Although texture is multidimensional, hardness and stickiness are critical and these textural characteristics govern palatability of cooked rice in Asian markets, with hardness being the most important and commonly measured parameter.

Rice texture is affected by factors such as variety, amylase content, gelatinization temperature, processing factors and cooking method. For instance, cooked rice with low amylase is soft and sticky while rice with high amylase is firm and fluffy. Sensory properties relating to stickiness had statistically significant correlation coefficients with amylose content (x0.31) and protein content (-0.67) .most hardness indices were positively correlated with amylase content where as indices of stickiness were negatively correlated with amylase content. Other important sensory textural characteristics were the mouthful properties of residual loose particles, tooth pack and starchy mouth coating, which showed significant correlation coefficients with protein content (x0.31). However, attempts to predict textural properties of cooked rice from compositional characteristics are still inadequate.

Storage time, temperature and duration influenced the texture of cooked milled rice. The texture of cooked aged rice was harder and less sticky than cooked freshly harvested rice, as measured by both sensory methods and texturometer the instron cooked rice hardness value of seven milled rice stored at 28-300c increased from 5.8 to 6.9kg during 3 months of storage and then leveled off. (Meullent et al 2000) investigated the effect of storage conditions of long grain rough rice on sensory profiles of cooked rice using sensory descriptive methods. They evaluated 10 sensory attributes and storage temperature influenced only textural characteristics. Perceived intensities from clumsiness, hardness, glueyness, cohesiveness of mass, and geometry of slurry were significantly different for a sample stored at various temperatures (4, 21 and 380c). Clumsiness and glueyness significantly decreased as storage temperature. Increase from 40c to 380c cooked kernel hardness was significantly greater in rice stored at 380c where as cohesiveness of mass significantly decreased with increasing storage temperature. Finally the geometry of the slurry was grittier for samples stored at 40c.

Similarly, rice stored at 400c showed a harder and less sticky texture when cooked than that stored at 4oC. During storage, retrogradation of the starch led to an increase in hardness as well as decrease in the adhesion of cooked rice. In general, as the degree of starch retrogradation increase during storage rice firmness increased and stickiness decreased.

In summary, hardness increases during storage although some work suggests that hardness reaches a maximum then decline. Most indices of hardness showed significant negative correlation with stickiness indices. Hardness was also affected by storage moisture content (R2=0.38). Tamaki et al reported that rice stored at 12% moisture content was initially found to be harder than rice stored at 15 to 18% moisture content. Meullenet et al (2000). also found similar results in that cooked kernel hardness decreased with increasing storage moisture and reached a maximum between 1 weeks and 22 weeks depending on the rough rice storage moisture content. A significant interaction was found between rough rice moisture content and storage duration. Increasing rough rice moisture and content delayed the perception of maximum hardness, although champagne et al (1999). Reported no difference in hardness as rough rice moisture content increased. Stickiness was greatest than a rice was freshly harvested and decreased with ageing or when treated to accelerate ageing. Tamaki et al year reported that rice stickiness measured by instrumental methods decreased consistently during.

The first 90 days of storage regardless of storage moisture content or storage temperature. Meullenet et al (1999) also reported that storage in the first 90 days of storage regardless of storage moisture content or storage temperature. Meullenet el al (1999). also reported that storage temperature and duration significantly affected adhesiveness to lips, and indication of rice stickiness (R2=0.58). Increasing storage temperature decreased rice stickiness. On the other hand, Tamaki et al year, reported that rice stickup reached a maximum after 20 weeks of storage and decreased significantly after 36 weeks of storage.


Moritaka and Yasumatsu (1992) proposed a mechanism of ageing involving lipids and proteins. lipids from free fatty acids, which can complex with amylase and carbonyl compounds and hydro peroxides, which can accelerate protein oxidation and carbonyl compounds hydro peroxides, which can accelerate protein oxidation and condensation plus accumulation of volatile carbonyl compounds. Protein oxidation (formation of deified linkages form sulphydryl groups) together with an increase in the strength of micelle binding of starch inhibits swelling of starch granules and a effects cooked rice textures. Mod et al year. proposed that oxidation of formulates esters of hemi cellulose would contribute to cross-linking and increase strength of cell wall during storage.

It is apparent that ageing is a complicated process involving physical, chemical and biological change. We propose that release of free phenolic acids alters integrity of the cell wall and at the same time the phenolic acids exert an effect via their antioxidant activity on the formation of FFA that can further complex with amylose during storage


Ageing commences before harvest and continues as a time, temperature, and moisture dependent index. Interactions amongst the variables are also important. The resulting polynomial models suggests that rice ageing is a complex process that is seen in the native rice grain, brown rice, milled rice, rice starch and cooked rice. Although the mechanism of rice ageing is not fully understood, appreciation of the changes during storage is important in the evaluation of milling cooking and eating quality. Storage conditions are important in the ageing process. Nitrogen was superior to air in preserving palatability of cooked rice during brown rice storage at 100c for 2 years. No great difference in quality was found between the brown rice stored in nitrogen or carbon dioxide. Storage in nitrogen had little effect on the texture changes of rice on cooking relative to storage in air. Hermetic storage of milled rice at 300c for 3 months under vacuum or in nitrogen, carbon dioxide and air atmospheres had little effect on reducing sugar, fat acidity, texturometer hardness and adhesiveness of cooked rice at 14.7% storage moisture. At 15.7% moisture storage, vacuum package showed the vast changes in reducing sugars, acidity hardness and adhesiveness, followed by gas package and then air package. Perez and Juliano (year) showed that at 150c ageing was most significant during the first 3 to 4 months of storage.

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A number of changes that impact on sensory quality have been observed in rice physical properties during storage. For example, one study identified eight textural properties that were important to sensory characteristics of cooked cyress rice as adhesion to lipid hardness, cohesiveness of mass, roughness of mass, tooth pull, particle size, tooth pack, loose particles. Post harvest storage conditions had significant effects on these properties. Tensile strength, crushing and breaking hardness and resistance grinding increased after ageing. During ageing of freshly harvested rice, regardless of storage form-rough (i.e. unprocessed rice), brown or milled, increase in volume expansion and water absorption was generally observed .Indudhara swamy et al (1978), reported an increase in water uptake for up to 1 year on storage, after which water uptake decreased, and these results have been substantiated.`


During the storage of rice, a number of chemical, physicochemical and biological properties changes occur. Thus they affect rice processing, eating, nutritional quality and product quality. These properties were cooking, texture, pasting properties, composition, sensory attributes and enzyme actives. Studies of rice storage have focused on whole-grain rice rather than the rice flour, for e.g., as rice aged, the cooked rice texture become harder and less stick than fresh one (meullent et al. 1999, 2000).

Another changes in RVA pasting characteristics after storage several months of milled rice (yasumatsu et al. 1964: sowbhagya and Bhattacharya, 2001). During the stooges of rice, the state flavor increases with an increase free acid and significantly deteriorates the flavor (Zhou et al. 2002). The storage change in swelling, color and dough leaving after 10 months stored rice flour was reported by charstil (1990).


The rice kernel is more than 90% carbohydrate. Reducing sugars (e.g. maltose) increase and non-reducing sugars (e.g. sucrose) decrease during storage when subjected to temperatures of 77f (25c) or greater. In contrast, degradation of carbohydrates to CO2 in generally very small, but can become significant at moisture contents greater than 14% and high temperatures. Similarly, total starch.



Rice sample were obtained from Ebonyi State Agricultural Development Programme (EBADEP). The rice varieties purchased were R5, R8, mars 308 and china. (control)

Each variety was divided into 2 parts. The proximate, functional and sensory characteristics was analysed on the first part. The second part was stored at ambient temperature (28-300c) for 3 months- before the same analysis was carried on them.


The proximate composition such as moisture content, ash content protein content, carbohydrate content and fat content were determined in all the processed samples.


The moisture content of the sample was determined using AOAC (1995) procedure. A clean crucible was dried, cooled. In a disscator weighed. About 39 of the sample was weighed into the crucible and put inside the oven (Ambassador Oven, model No 660) at 105+50c. The sample was brought out after every 2hrs and re-weighed until a constant weight was obtained.

The percentage moistures was calculated as follows

% moisture = w2 – w3 x 100

W2 – w1 1


W1 = weight of crucible.

W2 = weight crucible + sample

W3 = constant weight obtained after drying.



The percentage ash was determined by the method described by the national science and technology form (2004). An empty crucible was washed dried in an oven, cooked in a desiceator and weight. About 39 of the sample was weight into the crucible and incinerated into a carbolated furnace (530 2Ay England, SN; 10/90/1483) at 5600c till complete ash was obtained after 12hrus .the sample was cooled in a desiccators and weighed.

Percentage Ash = weight of crucible + ash)-weight of empty crucible

Sample weight.

Ash% = wt of Ash x 100

Wt of original sample



The fat content of the sample was determined by using Automated soxlet method (soxtec system HT2) grind and dry the sample and plug with cotton wool. Dry the thimbles. Insert the thimbles into the softens –HT. dry and weight the extraction cups (with boiling chips) add 25-50ml of the solvent into each cup. Insert the cup for 30-45 minis in “Rinsing” position. Evaporate the solvent Release the cups and dry at 1000c for 30mins, cool the cups in a desiccators and weigh.

% FAT (w3-w2) x 100

W1 1


Weight of the with the extracted fat = w3

Weight of the empty cup = w2

Weight of sample = w1

Protein determination (HACH 1990)

The protein content of the sample was determined of the method of Hach (1990) the procedure involves digesting the material with conc. H2S04 to dehydrate and char the sample (carbonization) and H202 to complete sample decomposition by providing a reducing environment, which helps in converting the nitrogen to ammonium salts. On treatment with a dispersing agent (poling) alcohol (PVA) the ammonium salt decomposes to liberate ammonia which is the presence of Neasler’s reagent gives an orange colour which is read at 460nm according to the specification of the Hach (1990) procedure manual.

0.25g sample was weighed into Hach digestion flask and 4ml of conc. Sulphur acid was added. The sample was transferred to the fume hood and heated for 5miuntes at 4400c to the charred sample was add 16ml of H202 to dear off the brown fume and make the digest colorless. The flask was taken off the heater, allowed to cool and the contents made up to 100ml mark with dermonized water mixed to 1ml of the digest was added 3 drops of mineral stabilizer and 5 drops to 25ml and 1ml of Nasser’s reagent was added. The colour was read within 5 minutes at 460nm on the Hach spectrophotometer against demonized water plank. The absorbance gives Mgli apparent nitrogen. The true Kjeldahl nitrogen is calculated as follows.

% N = 0.005625xA

B x C

Where A = mgli (reading displayed). B = ml or g sample digested and C = ml digest analyzed.



This was calculated by difference (AOAC,1990) 100 %-( fat + % protein + % Ash + % moisture.


Crude fiber was determined by the using of B. H2S04 method by Hach (1990). The method involves the digestion of the food material in boiled dilute acid to hydrolyze the carbohydrate and protein. This is followed by digestion in dilute alkali to effect saponification of the fat in the food material. Weigh 2g sample into a 600ml long beaker, add 200ml hot 1.25% H2S04, place because on digestion apparatus with preheated plates, boil and reflux for 0 minutes filter through Whitman hf /A paper by gravity or with the aid of vacuum/air pressure pump. Rinse the beakers with distilled water.

Until the filtrates is neutral. Transfer the residue from the paper back to the beaker with the aid of hot 1.2%. Na0H to 200ml.

Return the beaker to the digestion apparatus boil and reflux for 30 minutes. Filter through Whitman filter paper by gravity or with the aid of vacuum/air pressure pump. Rinse the beakers with distilled water; wash the residues on the paper with distilled water until the filtrate is neutral. Transfer paper with residue into a crucible. Dry sample at 1000c overnight, cool in a desiccators and weigh (weigh A). Put sample in furnace at 6000c for 6 hours. Cool in a desiccators and reweigh (weight B).

The loss in weight drying incineration represent the weight of crude fiber in the sample % crude fiber (weight A) – (weight B) x 100

Sample weight.


For the quantization determination of free sugar and starch a suitable solvent (95% ethanol) is used first to extract sugars from the starch the residue is then hydrolyzed with per choric acid into mono saccharides. The sugars are quantified calorimetrically using phenol and sulphuinc acid sugar gives an orange colour when treated with phenol and sulphuric acid. Sugars extracted with the solvent are directly analyzed to determine the sugar content. Sugar obtained after hydrolysis of the residue is converted to starch by multiplying it by 0.9



Weigh 0.020-0.25g flour or starch into centrifuge tubes; wet the powder with 1.0ml of ethanol. Add 2.oml of distilled water. Add 10ml hot ethanol and vortex. Centrifuge for 10 mins at 2000.pm decant supernatant into test tube, make it up 70ml extract


Colour development was determine by using an aliquot from 0.01 1ml of extract (0.2ml) for assay, Add o.8ml of distilled water. Add 0.5ml of 5% phenol and vortex, Add 2.0ml of conc. H2S04 and vortex. Cool and read absorbance at 490nm.


Starch was determine to the residue from sugar analysis add 7.ml of perchloric acid, let it stand for I hour, dilute the hydrolysate with 17.5ml distilled water and filer. Take 1.0ml of the filtrate and dilute with 1. 0ml of distilled water, vortex ready for assay.


Colour development was determine by using an aliquot of 0.01- 1.0ml of extract for analysis, develop colour with phenol and H2504 as in analysis of free sugars.


% sugar = (A-1) x O.F X V x 100

B x w x 106

% starch = (A-1) x O.F X Vx100x 0.9

B x W x 106

Where A = Absorbance of sample

1 = intercept of sample

O.F = Dilution factor (depends on aliquot taken for a assay)

V= volume

B = slope of the standard curve

W = weight of the sample.

Note: if intercept is negligible it can be overlooked


The wet-acid digestion method for multiple nutrient determination was used about 0.48-0.2g sample was weigh into a dean ceramic crucible record weight to the nearest 0.00lg. Include one empty crucible for a blank place in a cool muffle furnace and temperature to 5000c over a period of 2 hours. Allow to remain at 5000c for an additional 2 hour. Allow to cool in the over especially when ashing is done overnight (a) remove sample from oven making sure that your environment is free from breeze (b) pour the ashes sample first into your already numbered or babbled 550ml centrifuge tubes (c ) Repeal above two more times to make a total volume of 20ml vortex the sample for proper mixing. Centrifuge samples for 10mins 3000rep. decant supernatant into dean vials for macro and micronutrients determination using atomic absorption spectrophotometer.


About 10ml of the digest was pipette into conical flask potassium to prevent the interference of other was.

Calcium and magnesium form complex at a pH of 10.00, hence, ammonium butter (10ml) was added to raise the pH of the system to 10 with solochrone black 1 indicator. The system was titrated with 0.02N EDTA to a greenish and point calcium was determine alone by using about 10 NaoH butter to raise the pH to at which EDTA from complex with ca alone using solachrone drake blue indicator.

A blank determination was also carried out and titrated with the 0.02N EDTA reagent. The calcium and magnesium contents were obtained by multiplying the titration results by the factors 1.004 and 0.608 respectively.


The potassium and sodium contents were determined using the flame photometry method. About 5ml of the digest was pipette into a 50ml volumetric flask and diluted to 50ml with distilled water. A set of potassium and sodium was prepared coataning oppm, 2ppm, 4ppm, 6ppm, 8ppm and 10ppm of the elements in the solution. The flame photometer was switched on and the scale calibrated with 6ppm and adjusted to 60. The standard solution were tested and their values recorded. The appropriate fitter (photo cell) was selected for each element. The atomizer of the instrument was dipped into the sample and the meter reading taken the value obtained from the standards were used to plot the calibration curve for each test element and the concentration of the sample element determination by extrapolating form the graph as ppm of the curve. The potassium and sodium content were calculated by multiplying the calculated by multiplying the calculated valves by the factor 0.25.


The pH of the sample was determined using the method about 5g of the sample was weighed into 50ml of water and allowed to stand for 30min in 400c water both. The solution was filtered and the pH determined using pH meter (model micro processor pH meter: HANNA pH 211).

Determination early deturk precipitation the method by Balagopalon et al (1998) was used to extract the phosphorous present in the sample. The phosphorus extracted was analyzed using vanablo molly date method.

About 2.09 of the processed sample were dispersed in 10ml of acidified 10% Nas04 solution. This was stirred to mix very well and the mixture was left to stand at room temperature for hrs it was filtered using what man fitter paper (NoH2)

About 1ml of the extract was analyzed for phosphorus using the van ado molly date spectrometric method. Another 1ml of the extract was mixed with equal volume of distilled water followed by about 1.2ml of molar iron (iii) chloride (feds).The mixture was heated for Ihr in a water bath and centrifuged after cooling. About 1ml of the second extract was analysed for phosphorous.

The phytic acid content was calculated by the difference in phosphorus values from the two analyses after multiplying with the appropriate factor of 6” le px6 (six phosphorus atom in ach molecular unit of phytic acid structure

Phytic acid = p x 6

% p= 100 x Aµ x c x vf



Where w= weight of sample


Aµ = Absorption of sample

As = Absorption of standard

C = concentration of phosphorus standard

VF = total extract volume.

VA = volume of extract used. Of extract used



About 10g of the sample was weighed with an extraction tube and mixed with about 100ml of extracting solution (metaphosphonic acid acetic acid solution) and shacked for 30min in a mechanical shaker.

The sample was fettered through a No 42 what man filter paper into a 100lm volumetric flask and made up to the mark with the extractor.

About 20ml of the extracted was titrated with 0.02N Cuso4 solution using 10ml of potassium iodide and starch solution as an indictor. A blank sample was carried out using the extracting solution and the indicator. The values of the sample were substrate from the blank and ascorbic acid value mg/100g) was calculated by multiplying the obtained values by the factor 44.


Sensory evaluation of the cooked rice varieties was carried out by an untrained taste panelists in a special room prepared for the purpose (Ebuchi-et al, 2004). They were instructed to taste the sample and to rinse their month after each sample taste. They were requested to express their feelings about the sample by scoring the following attributes, taste, texture, colour, odour cleanliness and general acceptance. Sensory scores were based on a nine point hedonic scale, where / is dislike extremely and / is like extremely (watls et al, 1989).


Data generated were analyed using ANOVA and means separated using the Durican multiple Range method.


Table the proximate composition of four varieties of rice (milled)

S/N Sample %Protein %Fat %Ash % Fiber %M.C %Cho

1 R.5 8.35a 5.7a 3.05a 1.90a 8.13b 78.80a

2 R 8 7.56c 5.31b 2.26b 1.91a 7.80d 79.60a

3 mars 7.87b 4.69c 2.06d 1.84b 8.25a 80.10a

4 china 7.47d 4.35d 2.18c 1.90a 8.03c 80.91a

LSD (P<0.0.5) 0.057 0.057 0.015 0.845 0.015 3.350


Values are the means of duplicate determinations.

Means not followed by the same superscript in the same column are significantly difference (P<0.05)


Table the proximate compositions of four rice verities (milled and stored for three months

S/N Sample %Protein %Fat %Ash % Fibre %M.C %Cho

1 R.5 7.55a 4.77a 2.25a 1.10a 7.33b 78.00a

2 R 8 6.76c 4.51b 1.46b 1.11a 7.00d 78.80a

3 mars 7.07b 3.89c 1.26d 1.04b 7.45a 79.30a

4 china 6.67d 3.55d 1.38c 1.10a 7.23a 80.11a

LSD (P<0.05) 0.057 0.057 0.015 0.045 0.057 — —

Values are the means of duplicate determinations.

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Means not followed by the same superscript in the same column are significantly difference (P<0.05)

Values are the means of duplicate determination means not followed by the same superscript are significantly difference (p<0.05).

Table 4 and 4 shows the proximate composition of unstored and stored rice varieties respectively. The protein contents varied among the varieties in both unstored and stored samples. The brown rice had the highest protein content in the both tables which china variety had the lowest protein level. This is in agreement with the work Okaka et at, (2006) who observed that the nutrient content of broom rice is greater than that of polished rice. The storage period also influence the protein contents of all the varieties of rice tested. The storage period decreased the protein level of the rice varieties. The decrease so observed might be due to decrease in the water soluble amino acids. (Barber, 1972).

The fat contents of the samples varied significantly (p<0.05) among the rice varieties in both unstored and stored samples but storage period decreased the fat levels. The brown rice had highest fat contents(5.5% and 4.77) in both unstored and stored sample respectively, while china rice had the lowest fat levels(4.35 and 3.55) in both stored and unstored samples respectively. That decrease in fat content as a result of storage might be attributed to lipid breakdown by lipolytic activities during storage. Takano (1989) observed that lipid contents of rice are broken down to fatty acids and glycerol by lipases and phospholypase during storage.

Storage period decreased the ash content of all the varieties of rise tested. The mass varieties seemed to have the lowest level of ash in all the samples tested. However, the value of ash observed in table 4.1((unstored samples) are generally greater than that seen in table 4.2(stored samples). That decreases in the ash content with storage might be due to corresponding lose in moisture during storage which must have affected the mineral levels of the samples. However, there is significant difference (p<0.05) in the ash level with respect to the varieties tested.

Fiber levels of the rice varieties of storage also decrease slightly as a result of storage. The value of fiber recorded in table 4.1 was slightly greater than those observed in table 4.2. The china rice had the lowest fiber level in both tables as 1.84% and 1.04% respectively while the R8 variety had the highest levels of fiber as 1.9% and 1.11% in the both tables. The decrease in fiber levels as observed in this work may be due to some biochemical changes during storage.

The three months storage generally reduced the moisture contents of all the rice varieties tested. The moisture levels of unstored samples are greater than those observed in stored samples. Zhout et al.(2001) reported that storage time of rice reduces its moisture level. That might be due to moisture loss to the surrounding storage as observed by Ihekoronye and Ngoddi, (1985).

Carbohydrate levels of the samples varied among the varieties tested. Mass sample showed the highest carbohydrate contents in both stored and unstored samples. However, the three months storage slightly decreases the carbohydrate contents of the flour. The decrease in carbohydrate might be due to slight increase in the Alpha and Beta activities during storage which hydrolyse carbohydrate to simple sugars. (Ogu, 2003).

Table functional properties of four different varieties of rice (milled).


1 R.5 24.58c 11.76b 10.75c

2 R.8 25.68a 12.21a 11.88a

3 Mars 24.88b 11.56c 11.17b

4 China 24.88b 12.21a 11.88a

LSD (P<0.05) 0.095 0.160 0.270


Values are the means of duplicate determinations. Means not followed by the same superscript in the same column are significantly different (p<0.05).

Tables 4.3 and 4.4 shows the functional properties of four different varieties of milled rice stored for three months.


1 Brow Rice 23.68c 10.86b 9.85c

2 R.8 24.78a 11.31a 10.98a

3 Mass 23.98b 10.66c 10.27b

4 China 23.96b 11.30a 10.98a

LSD (P<0.05) 0.085 0.120 0.070

Values are the means of duplicate determinations. Means not followed by the same superscript in the same column are significantly different (p<0.05).

Table 4. 3 and 4.4 show the function properties of unstored and stored rice varieties respectively. The three months storage influenced the amylase content of all the rice varieties tested. The R8 variety had the highest amylase content in both samples (stored and unstored) the amylase content varied significantly (p<0.05) with the rice varieties both is unstored and stored samples. Indudhara (1978) reported that the functional properties of rice is influenced by the variety. The amylase properties also decrease with respect to the storage period. The decrease in the amylase activity as observed in this work might be due to increase in the amylases activity during storage which degrades both amylase and observed decrease in the amylase properties of rice during storage.

The swelling properties of the rice varieties decrease generally after three months storage. Though if it varied with the rice varieties in both the unstored and stored samples. The decrease in the swelling capacity of the rice varieties as a result of the three month storage might be due to increase in the viscosity of rice as observed by shibuya et al (1994) during 3 to 4 months storage. There was significant difference (p<0.05) with respect to rice varieties tested.

The percentage solubility of the different rice varieties were influenced by both the varietals difference and the storage time. R 8 and china rice varieties had the greatest percentage solubility in both unstored and stored samples. But generally the values observed in table (4.3 unstored is greater than those observed in table 4.4 (stored rice samples). The decrease in the solubility of the rice varieties so observed might be due to changes in the biochemical properties of rice during storage.

Table the sensory characteristics of cooked Rice varieties

S/N Sample Taste Texture Cleanliness Colour Odour General

1 R.5 5.2d 4.2c 4.2b 3.9b 3.5d 5.3a

2 R 8 6.8b 6.6a 8.0a 7.6a 6.0b 7.1a

3 Mars 5.9c 5.9b 6.8a 6.4a 5.4c 6.2a

4 china 7.2a 6. 3a 8.8a 8.4a 6.8a 6.8a

LSD (P<0.05) 0.20 0.31 2.30 2.51 0.33 2.00


Values are the means of duplicate determinations. Means not followed by the same superscript in the same column are significantly different (P<0.05).

Table sensory characteristics of stored and cooked rice verities

S/N Sample Taste Texture Cleanliness Colour Odour General

1 R.5 5.1a 4.6b 3.3c 3.4b 4.0b 5.3b

2 R 8 7.3a 7.0a 7.3ab 7.1a 6.5a 7.3a

3 Mars 6.4a 6.3a 6.0b 5.9a 5.9a 6.6ab

4 china 7.7a 6.7a 8.0a 7.9a 7.3a 7.5a

LSD (p<0.05) – – 0.79 1.80 2.30 1.83 1.70

Values are the means of duplicate determinations. Means not followed by the same superscript in the same column are significantly different (P<0.05).

Table 4.5 and 4.6 shows the sensory characteristics of unstored and stored rice varieties after cooking.

The china rice had the best taste in both unsorted and stored samples. Though the rice taste varied significantly (P<0.05) among the varieties, the storage time slightly increased the taste of the samples. That slight increase in taste as a result of storage might be due to biochemical changes during rice storage.

The texture of the rice varieties was influenced by both the varietals difference and the storage time. The R 8 variety had the highest texture in both stored and unstored samples (7.0 and 6.6) while the lowest texture was observed in broom rice variety. This is in agreement with the reports of Del Mundo et al (1989) who observed that rice texture is affected by factor such as variety, amylase content, processing factors and cooking methods the three months storage resulted to slight increase in the texture of the rice varieties. Person et al, (1999) reported that three months storage at 28oC to 30oC resulted to increase in the texture of cooked rice texture was significantly difference (P<0.05) from other varieties.

The cleanliness of the rice sample varied among the varieties but decreased after three months storage. The brown rice variety has the lowest cleanliness in both unstored and stored samples while the cleanliness of china rice was the best. The decrease in the rice cleanliness due to variety might be due to storage might be enzymes and non enzymes browning process during storage.

Storage period and varietal difference influenced the colour of the rice sample. The sensory results of this work shows that china rice had the best colour in both stored and unstored sample (7.9 & 8.4) the browning variety had the lowest colour in all the sample tested. The colour of the rice varieties were generally decrease by the 3 months storage time.

The odour of the rice samples varied significantly (P<0.05) due to variety in an instated rice but showed no significant difference (P>0.05) after three month storage. However, the storage time generally increased the odour of the sample. That might be due to the rapid increase in rice aroma during storage caused by corresponding increase in volatility of 2-acety 1-1-pyrroline (Buttery et al, 1986). The general acceptance of the rice varieties was influenced by storage period. There was no significant difference (P>0.05) with respect to unstored rice. The increased general acceptance of stored rice sample as seen in this work might be due to increased taste, texture and odour with respect to storage time.


The results of this research work shows that storage of rice at ambient temperature (28-30C) for 3 months decreased its nutrient contents. The rate of decrease in the nutrient content was observed to be dependent on variety.

The storage time also decreased the functional properties such as amylase, swelling property and solubility of the rice varieties. The rates of decrease in these functional properties were also dependent on the rice varieties. The results of the sensory analysis showed that three months storage increased taste, texture, odour and general acceptance but decreased cleanliness and texture.

Therefore the three months storage of rice is recommended for good sensory attributes and general acceptance.

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Rice Storage – Different Stages Involved, Effect On Quality Of Milled Rice

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