Rice is a versatile cereal and used for consumption in various forms.The three principal rice products of commercial importance which are traditionally being made in India are popped, puffed and flaked rice.Popped rice is a popular product, especially in Asia, because of its crispness and lightness.Hence an investigation was undertaken to study the varietal suitability of rice for popping quality characteristics.Sample of 15 paddy varieties were procured from ARS, Mugad.The physico-chemical parameters, cooking time and gelatinization temperature (GT) of milled rice and popping quality such as popping yield, expansion ratio of popped rice and flake size of popped rice were studied.Physical characteristics of milled rice varieties varied significantly (P<0.01).Among the milled rice varieties, the super fine variety Pusa-basumati had the highest length (7.22 mm) and the lowest in Dodiga (5.33 mm) a common grain variety.The L:B ratio for all the varieties of milled rice ranged from 1.89 to 3.68.In the study the popping yield was positively correlated with thousand kernel weight (r=0.332),bulk density (r=0.605), head rice yield (r=0.571), whereas the popping expansion was positively correlated to L:B ratio (r=0.527) and no significant correlation was found between popping expansion and amylose content and gelatinization temperature.The expansion ratio of popped rice of Intan found to be maximum at 27.6 per cent total amylose and 13.4 per cent hot water insoluble amylase.In the present study, it was observed that rice varieties Intan, Dodiga Udarsali, Navali, Abhilash, Jaya, Champakali posses good processing quality, exhibit optimum cooking time (19.00 to 23.50 min), high amylose content (27.6-30.6%db) and intermediate gelatinization temperature (70.09° to 72.45°C).Hence, it can be concluded that the rice varieties with high amylose content and intermediate gelatinization temperature are most suitable for good cooking, eating and processing qualities.

Despite the introduction of many PSB Rc varieties with similar intermediate apparent amylose content (AC) and intermediate starch gelatinization temperature (GT), IR64 continued to be the variety of choice among traders and processors. The grain quality of aged,milled rice of PSB/NSIC Rc and selected IR varieties grown during the 2002 dry season was compared to characterize and subject the values to cluster analysis. Three clusters plus IR29 were obtained based on physical properties alone, and four clusters were obtained based on both physical and eating properties. IR64 was shown to belong to cluster 1 based on physical and eating qualities together with PSB Rc18, PSB Rc14, PSB Rc42, PS13 Rc64, PSB Rc72H and Sinandomeng. Consumer evaluation of selected PSB Rc rices and IR64 from the clusters showed that in raw form, intermediate-AC intermediate-GT PSB Rc18, PSB Rc72H F-2, PSB Rc14 and low-GT PSB Rc12 had higher to comparable consumer scores than IR64. Low-AC NSIC Rc104 with short, bold grain had the lowest score for raw rice. Although IR64 had better scores for cooked rice than high-AC rices in clusters 2 and 4, PSB Rc72H F2 and PSB Rc42 cooked rice had higher consumer rank score and consumer rating than IR64. PSB Rc18, PSB Rc14 and PSB Rc64 all in cluster 1 had comparable cooked-rice scores to IR64. Low-GT PSB Rc12 had lower rank score for cooked rice than other intermediate-AC rices with intermediate GT. Consumer rating should be evaluated further as a promising replacement for consumer preference rank score of rice samples. Among japonica (PJ) type rices, intermediate GT among waxy and low-AC entries had harder staled cooked rice than low-GT entries, but among intermediate AC entries, even the fresh cooked rice of low-GT entries tended to be harder than intermediate-GT entries, just as in PSB Rc14 and PSB Rc12.

The nutritional bioavailability of zinc from cooked milled, undermilled, and brown Philippine rice (variety PSB Rc14) was evaluated in rats, comparing results based on weight gain, tibia zinc incorporation (slope ratio analyses), and zinc radiotracer retention. Milling reduced the phytic acid and mineral content of the rice, resulting in zinc concentrations of 16.5, 19.4, and 27.2 microg/g and phytate/zinc molar ratios of 4, 20, and 28 for milled, undermilled, and brown rice, respectively. Measured zinc bioavailability was similar whether using growth, bone zinc, or radioisotope retention as criteria, at approximately 92, 86, and 77% of zinc sulfate, for milled, undermilled, and brown rice, respectively. However, the higher percent bioavailability of the zinc after milling was insufficient to compensate for the lower zinc content. With respect to zinc, the nutritional value was inversely related to milling, providing approximately 15, 17, and 21 microg bioavailable zinc/g rice, respectively, for milled, undermilled and brown rice of this variety.

The aroma compounds present in cooked brown rice of the three varieties Improved Malagkit Sungsong (IMS), Basmati 370 (B 370), and Khaskhani (KK), and of the variety Indica (German supermarket sample), were identified on the basis of aroma extract dilution analyses (AEDA). A total of 41 odor-active compounds were identified, of which eleven are reported for the first time as rice constituents. 2-Amino acetophenone (medicinal, phenolic), which was up to now unknown in rice aroma, exhibited the highest flavor dilution (FD) factor among the 30 to 39 odor-active compounds detected in all four varieties. 2-Acetyl-1-pyrroline, exhibiting an intense popcorn-like aroma-note, was confirmed as a further key aroma constituent in IMS, B 370, and KK, but was not important in Indica. Differences in the FD factors between the varieties were found for the previously unknown rice aroma compound 3-hydroxy-4,5-dimethyl-2(5H)-furanone (Sotolon; seasoning-like), which was higher in B 370 than in IMS and KK. In IMS, a yet unknown, spicy smelling component with a very high FD factor could be detected, which contributed with lower FD factors to the overall aromas of B 370 and KK, and was not present in Indica. The latter variety, which was available on the German market, differed most in its overall aroma from the three Asian brown rices.

College,Laguna, Philippines.Received 1 ABSTRACT Eight indica and japonica milled rices with low amylose content and low starch gelatinisation temperature were analysed for cooked rice energy and N balance in growing rats and for protein properties. Digestible energy values were similar. Japonica rices Koshihikari and Sasanishiki had higher true digestibility (TD) and net protein utilisation in rats than indica rices IR24 and PR23383-15. Similar results were obtained from in vitro proteolysis. High TD of cooked rices was not significantly correlated with low prolamin content in raw rice and with low waxy gene product (protein bound to starch granule) but was significantly correlated with low cysteine content in protein and with low denatured prolamin content in cooked rice. In two pairs of cooked waxy milled rices, which are devoid of waxy gene product, japonica rice still tended to show higher rat TD and in vitro protein digestibility than indica rice, consistent with lower cysteine content in japonica protein.

ABSTRACTThe differences in pasting properties involving gelatinization and retrogradation of rice starches from IR24 and Sinandomeng cultivars during heating‐cooling processes were investigated using a Rapid Visco Analyser (RVA)and a dynamic rheometer. The results were discussed in relation to the molecular structure, actual amylose content (AC), and concentration of the starches. Generally, both starches possessed a comparable AC (≈11 wt%), amylose average chain length (CL), iodine absorption properties, and dynamic rheological parameters on heating to 95°C at 10 wt% and on cooling to 10°C at higher concentrations. In contrast to Sinandomeng, IR24 amylose had a greater proportion of high molecular weight species and number‐average degree of polymerization (DPn). IR24 amylopectin possessed a lower DPn and greater CL, exterior CL (ECL), and interior CL (ICL). Comparing the results of RVA analysis and dynamic rheology, the gelatinization properties and higher retrogradation tendencies of IR24 starch can be related to the structural properties and depend on starch concentration. In addition, the exponent n of starch concentration for storage moduli at 25°C (G′25 ∝ Cn) increased linearly with increasing AC.

The kinetics of preparation of amylodextrin (Lintner starch) was studied at 50 C as 35% rice-starch slurry in 1.0 M HCl. Based both on recovery of amylodextrin and amount of solubilized starch, under low and intermediate-high gelatinization temperature (GT), the amorphous fractions in two waxy and six non-waxy rice starches were corroded within 2 h of hydrolysis, after which the hydrolysis rate decreased. The change in slope was more pronounced in low-GT starches than in intermediate-high-GT starches. After 12-14 h, a third stage was noted, wherein an increase in hydrolysis rate was observed. This is possibly due to partial gelatinization of the amylodextrin and subsequent hydrolysis. Scale preparation from intermediate-high amylose-content rices for 18 h yielded 60-75% amylodextrin. Recovery of amylodextrin in both experiments was consistently higher from intermediate-high GT starch than from low-GT starch; amylose content had no effect. Differential scanning colorimetry revealed the temperature and enthalpy of gelatinization to be lower in the 18-h amylodextrin than in the native starch, but temperature was higher than 50 C. Mayonnaise prepared at 50 C (where aqueous gel of the 18-h hydrolysis amylodextrin of non-waxy flour and starch replaced 50% of the fat) was satisfactory and better than that obtained using raw rice starch.

A population successful in an ecological niche must have a dietary pattern that provides the minimum requirements of all 40-45 essential nutrients, in addition to the energy sources-carbohydrates, fat, and protein. Cereal production and its contribution to diets in developing countries exceed that of legumes and roots, tubers, plantains and bananas. Legumes are highest in protein and is rich in lysine but deficient in cystine and methionine. Cereals are intermediate in protein content; their protein is rich in cystine and methionine but deficient in lysine. Thus cereal-legume diets have a better amino acid balance than either diet alone, as shown by the high protein quality of most composite diets. Storage proteins are prolamin and glutelin in cereal endosperm, but globulin in legume cotyledon, occurring as prolamin protein body (PB) in cereals and globulin PB in legumes. Glutelin PB occurs in rice endosperm. Roots, tubers, plantains and bananas are high in moisture, hence, poor in protein content and other nutrients and have a poor postharvest shelf life. Potato protein has a balanced amino acid composition. Antinutrition factors for protein include protease (trypsin) inhibitor, tannins, and phytate.Digestible energy correlates with true protein digestibility and increases with processing. Starch occurs as partially crystalline storage granules. The amylose content of starch correlates negatively with glycemic index and positively with resistant starch, a component of soluble dietary fiber. In some cases, starch gelatinization temperature correlates negatively with glycemic index and positively with resistant starch. Antinutrition factors for starch include amylase inhibitor, tannins, and phytate. Flatulence factors include galactose-containing oligosaccharides, which are particularly high in legumes, Soluble a-glucans of oat and barley have hypocholesterolemic activity.Legumes are generally energy-dense due to their high fat content, particularly peanut and soybean. The unsaponifiable matter of rice oil has hypocholesterolemic activity. Some varieties of root crops have cyanogenic glycosides that release HCN on hydrolysis, causing death to consumers. Others have saponins and tannins that contribute to a bitter taste. Staple foods are a major source of vitamins and minerals due to the large amount consumed.Breeding efforts in the 1960s and 1970s attempted to improve the protein content and limiting amino acid (lysine content in cereals and cystine and methionine in legumes) in staple foods, both of which require more energy to produce. CGIAR recently launched a project to increase the micronutrient density of selected crops, particularly vitamin A, iron, and zinc, although mineral absorption from a vegetable sourer is poor. The low phytate mutant of cereals may improve protein digestibility, glycemic index, and mineral absorption. Rice mutant lacking lipoxygenase 3 and a lower polyunsaturated fatty acid content may reduce fat rancidity and maintain the essential fatty acid level of food during storage, as in soybean.The adoption of GATT-WTO in most countries, the accompanying emphasis on value-added food products, and the popularization of functional foods and nutraceuticals in developed countries will have an impact on the properties and nutritive value of food products in developing countries in the 2000s.

ABSTRACTStarches of waxy rices that showed varietal differences in hardness testing of cooked rice after amylopectin staling and high‐amylose content (AC) rices differing in gel consistency (GC) and starch gelatinization temperature (GT) were studied to determine the factors related to varietal differences in amylopectin staling of cooked rice. Intermediate‐ and high‐GT starches showed greater amylopectin staling of gelatinized rice by hardness testing values or differential scanning calorimetry (DSC) endotherm than did low‐GT starches in both waxy and nonwaxy rices. Isoamylase‐debranched amylopectins of waxy rices differed in the ratio of weight‐average degree of polymerization (DPw) fractions, but these fraction ratios were not simply related to differences in amylopectin staling of cooked rice. Among high‐AC rices, amylopectin from low‐GT starch was confirmed to have higher iodine affinity (2.3–2.5%) than amylopectin from intermediate‐GT starches (1.7–1.8%), regardless of GC. Within high‐AC starch of the same GT type, soft‐GC rice corresponded with more A + B1 DPw 16–18 and less B3 DPw 150–200 fractions of debranched amylopectin and low DPw of amylose. Amylopectin of amylose extender mutant of IR36 was confirmed to have a longer chain length than ordinary rice amylopectin: the debranched amylopectin has more B2 DPw 47–51 fraction, less A + B1 DPw fraction, but no B4 fraction with DPw > 200. Only high‐AC amylopectin had debranched fraction with DPw >120.

Declining per capita consumption of boiled rice in Asia has accelerated national research and development on rice processed products to help maintain rice consumption levels. The processing of rice and the eating quality of the product are influenced by a number of functional properties which derive from the rice composition. The ratio of amylose to amylopectin in starch as indexed by apparent amylose content (AC) of milled rice is the chief influence on processing and eating quality. It correlates negatively with taste panel scores for cohesiveness, tenderness, and gloss of boiled rice. Most tropical nonwaxy varieties have ACs of 20% or higher. Japanese and Koreans prefer low-AC rice (16%), while Filipinos, Indonesians, Malaysians, and Thais prefer 18-22% AC rices. Processed rice products were surveyed, with emphasis on Asia. Waxy rices are used in desserts, cakes, and sauces, low-AC rices in baby foods and breakfast cereals, intermediate-AC rices in canned soups and fermented rice cakes, and high-AC rices in rice noodles.

Cereal Chem. 73(5):556-560 Rice yields of 10 and 6 t/ha can be achieved in the humid tropics dur- improved, but Kett whiteness decreased with late N fertilizer application. ing the dry and wet seasons, respectively. At these high yield levels, late Brown-rice weight was not affected by late N application. In most cases, nitrogen (N) fertilizer application at flowering at the International Rice there was a significant positive correlation between head rice content, Research Institute (IRRI) farm often results in increased rough rice yield milled rice protein, and translucency. Thus, when crop management of IR cultivars and is accompanied by higher milled rice protein and seeks to achieve yields that approach yield potential levels, late N fertilincreased total and head-milled rice contents. The combined effects of N izer application provides an option to improve milling and nutritional application at flowering resulted in a 30-60% increase in head-rice pro- quality of rice grain. tein yield in three field experiments. In general, milled rice translucency A yield decline has occurred in several long-term experiments where continuous irrigated rice is grown in the Philippines (Flinn and De Datta 1984, Cassman et al 1995). In recent studies to identify the cause of decreasing yield trends at the International Rice Research Institute (IRRI) farm, increased nitrogen (N) fertilizer rates including a top-dressing applied at flowering stage was found to increase the yield of IR rices (Cassman et al 1993, 1994). It was hypothesized that the current low yields at the IRRI farm were partly related to a change in the N supplying capacity of soil which results in low N concentration in the leaf canopy during the grain filling period, early senescence of leaves, and low rates of photosynthesis (Kropff et al 1993; Cassman et al 1995). Consistent with this hypothesis, grain protein content also appears to have decreased. For example, mean protein content of milled rice was typically =7% in the 1960's and 1970's at the IRRI farm in plots without applied N (Cagampang et al 1966, Eggum and Juliano 1975, Gomez and De Datta 1975), whereas grain protein from 0-N IRRI field plots (block B4) in the 1991 wet season was only 5.5% for IR72 and 5.0% for IR58109-113-3-3-2 (IRRI, un

Maintenance of grain quality is the major consideration in postharvest handling of grains. Grain quality is influenced by variety, preharvest environment, and postharvest handling. Grain breeding programs concentrate on varietal improvement, whereas engineers improve postharvest processes to enhance grain quality. Major grain quality problems arise from lack of incentive to farmers, and are manifested in yellow rice, brokens, ageing and storage changes, variety mixing and mislabelling, and lack of screening methods to differentiate among rices with similar starch properties and among special rices for rice food products. High aflatoxin level from fungal growth is the major problem for maize and parboiled rice. Fissuring during drying is also a quality problem in maize.Specific grain properties relevant in drying include moisture content (water activity) and both critical and equilibrium moisture contents, and hull or husk tightness. Delayed drying may result in stackburning of wet grain due to nonenzymic browning and microbial growth and mycotoxin production in maize and parboiled rice. Improper and over-drying may reduce head rice yield and aroma. Rice varieties differ in their critical moisture content (11-16%, below which they fissure readily) and in equilibrium moisture content. Further interdisciplinary research should accelerate the solution of quality problems related to postharvest handling of grain.

The nutritive value of cooked milled rice of one glutelin mutant esp-2 and three prolamin mutants esp-1, esp-3, and Esp-4 backcrossed twice to Kinmaze and differing in their protein subunit ratios were evaluated by chemical analyses and balance studies in growing rats and compared with the Kinmaze parent. The glutelin mutant had higher lysine content and true digestibility (TD) of protein than did Kinmaze, but all had digestible energy values similar to that of Kinmaze. The esp-3 prolamin mutant was confirmed to have lower sulfur amino acids in protein than did the other samples, but lysine was still the limiting amino acid. Biological value of the mutants was similar to that of Kinmaze, but net protein utilization (NPU) of esp-2 and Esp-4 was higher than that of Kinmaze. The 10- and 16-kDa prolamin-rich mutant Esp-4 had even higher TD than that of Kinmaze. The glutelin mutant had best protein quality among the four Kinmaze mutants.

The in vitro and in vivo resistant-starch (measured in growing rats) levels were low in five raw rice cultivars differing in apparent amylose content, and the values were correlated positively with amylose content. Cooked and cooked parboiled rices generally had higher resistant-starch contents than raw rices, particularly those with intermediate gelatinization temperature starches, but waxy rice had very low values. Values for undigestible energy, which is mainly in the form of unfermented energy and undigestible protein, were similar in raw rices, but increased with processing, particularly in the higher-amylose rices. In vivo resistant starch was not correlated significantly with undigestible energy and undigestible protein, but undigestible energy and protein were correlated with each other. Parboiling was calculated to increase the resistant-starch content of cooked rice by not more than 1%. Thus, cultivar differences in cooked-starch digestibility were reflected less in levels of resistant starch than in the rate of starch digestion as indicated by glycaemic and insulin response.

The thermal and mechanical properties of concentrated (25–35% w/w) starch gels of 43 non-waxy rices, varying in their amylose content and gelatinization characteristics, were investigated by small amplitude oscillatory shear measurements and differential scanning calorimetry. The storage modulus (G') of freshly prepared gels increased exponentially with increasing amylose content. An inverse linear relationship was also found between tan δ and amylose content (r = −0.75, p < 0.01). All high-amylose (>29%) rice starch gels exhibited tan δ values less than 0.1, indicating well cross-linked networks. At starch concentrations within 10–25% (w/w), the dependence of storage modulus on concentration followed power law relationships; G' varies as C2.2–2.9 (r>0.96, p<0.01). Changes in gel rigidity (G') upon storage were not solely dependent on amylose content. Kinetic experiments on staling of gels (35% w/w, 8°C) by calorimetry indicated that granular lipids retarded this process; the effect was more pronounced for low-amylose rice starches.

Determinations were made of the critical moisture content (CMC) in selected IR varieties and other rough rices after harvest in both dry and wet seasons at the International Rice Research Institute. Below the CMC, the grain becomes susceptible to fissuring. The rices were dried to moisture contents of 10-20%, wb, stressed by soaking in water for 2 hr, and redried before milling. Susceptible variety IR42 had a CMC of 16% in both crops, whereas resistant variety IR60 had a CMC of 14% in the dry season and 12% in the wet season. Grain for the moisture-adsorption stress test was shade-dried to 14% moisture, verified as optimum. The CMC obtained from dried grains, adjusted to higher moisture content by moisture adsorption before stressing, did not effectively distinguish among IR rices. Flash-drying of all freshly harvested grain to a target moisture content of 20 +/- 5% may be employed without danger of grain cracking.