Investigation of changes in chemical composition and rheological properties of Kyrgyz rice cultivars (Ozgon rice) depending on long-term stack-storage after harvesting

Effect of storage time on chemical compositions, physiological and cooking quality characteristics of different rice types

BACKGROUND

Storage affects rice quality significantly. The aim of this study was to investigate the changes in the chemical composition and in the physiological and cooking quality characteristics of three rice types after 1 year storage at 25 °C.

RESULTS

Two japonica, two indica, and two indica-japonica hybrid rice varieties were selected. After storage, the total starch content decreased. The amylose content of japonica, indica, and indica-japonica hybrid rice increased by 9.63%-11.65%, 2.99%-4.67%, and 8.07%-8.97%, respectively, and the fat content decreased by 60.00%-65.00%, 37.21%-46.51%, and 41.67%-42.42%, respectively. The abscisic acid (ABA) and raffinose content decreased after 1 year's storage; the former decreased gradually during the storage and the latter increased by 19.35%-45.45%, 7.02%-10.77%, and 16.13%-28.13%, respectively, after 4 months' storage and then decreased to the lowest level after 1 year's storage. The activity of antioxidant enzymes deceased, which resulted in the increases in fatty acid value and malondialdehyde (MDA). The changes in chemical composition after 1 year storage led to the deterioration of rice cooking quality, which was reflected in the decrease in viscosity and increases in gelatinization temperature and cooked rice hardness.

CONCLUSION

After 1 year's storage, the rice chemical composition changed and physiological and cooking quality characteristics decreased. Compared with japonica and indica-japonica hybrid rice, indica rice was more stable during 1 year storage. This may be due to the higher content of ABA and raffinose in fresh rice. Our findings will provide information for the identification and breeding of storable rice cultivars. © 2022 Society of Chemical Industry.

Screening new breeding japonica rice varieties by rice quality, three processing characteristics, and odor characteristics

Rice's yield, cooking, and sensory quality are primary considerations in selecting new breeding rice varieties, which are determined by the rice eating quality such as processing and flavor characteristics. Thus, in this study, to advance the breed of new superior japonica rice varieties, the differences in the rice quality, processing characteristics, and flavor characteristics between 12 newly-bred varieties (H2-36, H2-42, H2-53, H2-59, H2-63, H2-73, H2-74, H2-79, H2-81, H2-82, H2-89, and H2-91) and 1 commercial variety (Kenyu38) were analyzed. The results indicated that H2-42 has a reasonable length-to-width ratio (1.51), high rice yield, good color, reasonable amylose, protein content, excellent water existence index, accessible storage, and the highest taste value. Electronic nose results showed significant differences in aldehydes, ketones, and alcohols among 13 rice varieties. Aroma analysis results showed that H2-42 had the highest n-hexanal (14.63 µg/kg), (E,E)-2,4-nonadienal (37.24 µg/kg), nonanal (19.93 µg/kg), and decanal (4.81 µg/kg); those were important aroma components in cooked rice. The Pearson correlation analysis showed that hardness, springiness, cohesiveness, trough viscosity, peak time, and pasting temperature were the crucial factors that affected rice quality. According to partial least squares regression analysis, total color change, final viscosity, setback, (E)-2-heptenal, and 2-methyl-undecanol were the most important factors that distinguished the rice quality. In conclusion, H2-42 rice was better apparent quality, processing characteristics, and aroma compounds. Therefore, H2-42 has the potential for identification and promotion. PRACTICAL APPLICATION: The results from this study will provide data support for the cultivation, application, and quality improvement of high-quality rice varieties. In addition, it gives new ideas and methods for studying rice eating quality.

Grain Dimension, Nutrition and Nutraceutical Properties of Black and Red Varieties of Rice in India

Traditional colored rice varieties in India are the source of carbohydrates, phytochemicals and minerals. They facilitate the growth of probiotics in intestine and protect human from many chronic diseases. The present study investigated the nutritional properties such as total sugars, digestible sugars, resistant sugars, hydrolysis index, glycemic index and total proteins of thirteen colored varieties of rice in India. Nutraceutical properties like anti diabetic and prebiotic activity were investigated by standard methods. Chak hao poreiton and mappillai samba grains were 6.3 mm in length. Lowest length of 5.1 mm was recorded in 60 m Kuruvai. Among the rice varieties, mappillai samba has high concentration of digestible starch of 91% and Chak hao poreiton had low concentration of 62%. Resistant starch was 38% in Chak hao poreiton and 8% in mappillai samba. Lowest glycemic index of 52 and 53 were recorded in karuthakar poha and Chak hao poreiton respectively. Anthocyanin extracted from Chak hao poreiton inhibited 24% of human pancreatic α-amylase activity. It significantly increased the probiotic number from 0.15 CFU/mL to 1.95 CFU/mL. The study revealed that the black rice variety, Chak hao poreiton was rich in resistant starch and exhibited low glycemic index. The anthocyanins from Chak hao poreiton possessed significant antidiabetic and prebiotic activity. Molecular docking studies revealed the interaction of anthocyanin with pancreatic α-amylase, β-glucosidase and GLUT1.

Effect of sweeteners and storage on compositional and sensory properties of blackberry jams

Sweeteners of natural sources, such as sugar alcohols, are in the centre of growing interest. Their impact on the phytochemicals, antioxidant and sensory properties of blackberry jams were investigated during a 9-months storage period. Measurements on jams prepared with different sugars and sugar alcohols (sucrose, fructose, xylitol and erythritol) were performed at the date of preparation and in the 1st, 3rd, 6th, 9th month.

Total polyphenol content, individual polyphenols, antioxidant properties, anthocyanin content and CIE L*a*b* colour were determined. Sensory profiles were determined by a trained panel. Sensory attributes were compared by the results of the electronic tongue and nose.

Sweeteners had a significant impact on physicochemical properties and sensory attributes. Storage time also affected the sensory and compositional properties of jams. Changes in antioxidant properties did not follow a clear trend during the storage period, and antioxidant capacity was not affected significantly by the sweetening agent, but showed a significant decline from the 6th month. A positive effect of xylitol was observed in terms of a low degradation rate of anthocyanins, while their decomposition was the fastest in the fructose-containing preparation. Jams sweetened with erythritol reached significantly lower values for some sensory attributes (blackberry flavour and general taste intensity), however, they showed more intense red colour. Multiple factor analysis enabled the identification of the effect of sweetener and storage time on the pattern of the sensory data matrix. Classification according to individual sweeteners was performed successfully by the electronic tongue, but not by electronic nose.

Investigation of changes in rheological properties during processing of fermented cereal beverages

Many indigenous fermented foods and beverages consumed throughout the world are produced at home or in crafts enterprises. The production of fermented beverages on a large commercial or industrial scale requires clearly established technical and technological requirements. This study shows a novel way to investigate the optimal process parameters of the Kyrgyz traditional fermented beverage Bozo using rotational rheological parameters. Five significant process parameters were investigated like cooking of millet porridge, the mashing temperature, the mashing time under conditions of mixing and viscosity changes of the end product during storage. According to the gelatinization temperature of millet porridge, cooking parameters were recommended at T = 79 °C and t = 30 min. The optimum mashing temperature of millet porridge was determined to be 65 °C and mashing time under stirring conditions of millet porridge was found to be 10 min. The viscosity of the beverage Bozo was investigated after 7, 14 and 21 days of storage at 5, 10, 20, and 30 °C. The effective viscosity of Bozo was calculated using the Casson model, which increased from 39.67 to 51.25 Pa·s after 21 days of storage. The effect of temperature on effective viscosity of Bozo and the activation energy was calculated using an Arrhenius-type equation. The parameters obtained make it possible to provide food manufacturers useful information for boiling, mashing and storage parameters after fermentation as well as quality control of Bozo.

Evaluation of physical properties of rice used in traditional Kyrgyz Cuisine

Eight staple rice cultivars consumed in Kyrgyzstan were evaluated for physical properties in this study. The dimensions of investigated grains correspond to 5.29-6.99 mm for length, 2.52-3.10 mm for width, and 1.88-2.13 for thickness. Equivalent diameter was in range of 3.14 - 3.47 mm, surface area took 25.35-31.90 mm². The sphericity analysis values varied from 0.480 to 0.559, aspect ratio from 0.39 to 0.55, volume of the grain was measured in range from 16.25 to 22.02 mm3, bulk density values were 0.77-0.87 g/cm3, and solid density from 1.17 to 1.41 g/cm3. The porosity of grain was equal to 28.27-39.83%, thousand kernel weight correspond to 19.67 to 27.15 g, rupture force of grain was measured in range of 63.47-155.50 N, color characteristic varied in parameters L*, a* and b*, 37.58-72.19, -0.22-10.17, and 9.65-21.12, respectively. Optimum cooking time ranged from 19.33 to 33.00 min. The water uptake ratios for 30 min of soaking were 1.21-1.28, 1.18-1.45, and 1.14-1.57 for 30, 45, and 60°C, respectively. While the water uptake ratios for 60 min of soaking were 1.22-1.42, 1.19-1.54, and 1.25-1.75 for 30, 45, and 60°C, respectively. Optimal cooking time showed that imported varieties needed lower interval for full grain cooking compared to the local Kyrgyz varieties. It was found that Kyrgyz rice varieties staying more firm after cooking as compared to imported varieties and therefore more suitable for the local traditional dish such as plov.

Effect of nano packaging on preservation quality of Nanjing 9108 rice variety at high temperature and humidity

A nano packaging material containing nano Ag, nano TiO₂, nano attapulgite and SiO₂ was prepared, and its impact on quality of Nanjing 9108 rice at 37°C and 85% relative humidity was studied. Effects of the packaging on ambient gases and chromatic aberration of rice were determined. Moreover, oxidation level, molds growth and flavor of rice were also analyzed. Results showed that nano packaging material had antimicrobial effects and maintained low O₂ and high CO₂ content in the packages. The packages thereby inhibited the growth of molds and the production of fatty acids, restrained the increase of lipase activity, and reduced the oxidation of fats and proteins. As a result, the production of yellow and white-belly rice were inhibited. Furthermore, the color and flavor of rice were maintained. Therefore, the nano-packing material could be applied for preservation of rice to improve preservation quality.

Rice protein radicals: growth and stability under microwave treatment

Carbon-centred radicals are revealed in the microwave treated rice protein samples. The change of protein structure in a microwave field is often presumed to be caused by free radicals.