Effect of soaking medium on the physicochemical properties of parboiled glutinous rice of selected Laotian cultivars

Influence of parboiling conditions on rice grain quality characters and insect infestation with rice weevil (Sitophilus oryzae. L) of some rice cultivars

Parboiling improves rice grain hardness and reduces susceptibility to Sitophilus oryzae infestation by gelatinizing the starch and enhancing resistance.A newly designed electric machine was used to parboil four Egyptian rice cultivars-Sakha 108, Giza 178, Super 300, and Egyptian Yasmin-at 70, 75, and 80 °C and determine their susceptibility to Sitophilus oryzae L. (Coleoptera: Curculionidae) infestation. Results indicated that heating affected most traits in all four rice cultivars during both study seasons 2021 and 2022. Super 300 rice cultivar exhibited the highest hulling values (81.23 and 81.42%) when heated to 80 °C, while the Yasmin rice cultivar showed the lowest values for hulling (77.66 and 77.45%) at 70 °C. while Giza 178 cultivar showed a significant decrease in broken percentage (90.85 and 94.02%) compared to control when heated to 80 °C. The results also indicated that the Yasmin rice cultivar had the highest values for white belly, hardness, and gel consistency at 80 °C, while the Sakha 108 cultivar showed the lowest values for these traits at 70 °C. Furthermore, the protein, elongation, and water uptake characters significantly responded to the different investigated treatments. Yasmin cultivar at 80 °C showed the highest significant values for protein (9.26 and 9.47%), elongation (65.02 and 65.44%), and water uptake (453.2 and 455.1 ml water/100 g milled grains) in both seasons. Sakha 108 cultivar had the lowest values for these traits at 70 °C. The S. oryzae insects responded differently to the rice cultivars. Using Dobie's Index of Susceptibility, all cultivars were classified as resistant to S. oryzae infestation. Super 300 was moderately resistant before parboiling but resistant after heat treatment. In conclusion, the study underscores the influence of pre-storage parboiling on rice weevil infestation, suggesting that heat treatment could serve as an effective control measure. These findings emphasize the importance of parboiling conditions in enhancing rice grain quality and bolstering resistance to insect infestation.

Determination and prediction of amino acid digestibility in brown rice for growing-finishing pigs

OBJECTIVE

The experiment aimed to determine the standardized ileal digestibility (SID) of crude protein (CP) and amino acids (AA) in 10 brown rice samples fed to pigs, and to construct predictive models for SID of CP and AA based on the physical characteristics and chemical composition of brown rice.

METHODS

Twenty-two cannulated pigs (initial body weight: 42.0±1.2 kg) were assigned to a replicated 11×3 incomplete Latin square design, including an N-free diet and 10 brown rice diets. Each period included 5 d adaptation and 2 d ileal digesta collection. Chromic oxide was added at 0.3% to all the diets as an indigestible marker for calculating the ileal CP and AA digestibility.

RESULTS

The coefficients of variation of all detected indices for physical characteristics and chemical composition, except for bulk weight, dry matter (DM) and gross energy, in 10 brown rice samples were greater than 10%. The SID of CP, lysine (Lys), methionine, threonine (Thr), and tryptophan (Trp) in brown rice was 77.2% (62.6% to 85.5%), 87.5% (80.3% to 94.3%), 89.2% (78.9% to 98.9%), 55.4% (46.1% to 67.6%) and 92.5% (86.3% to 96.3%), respectively. The best prediction equations for the SID of CP, Lys, Thr, and Trp were as following, SIDCP = -664.181+8.484×DM (R2 = 0.40), SIDLys = 53.126+6.031×ether extract (EE)+0.893×thousand-kernel volume (R2 = 0.66), SIDThr = 39.916+7.843×EE (R2 = 0.41), and SIDTrp = -361.588+4.891×DM+0.387×total starch (R2 = 0.85).

CONCLUSION

Overall, a great variation exists among 10 sources of brown rice, and the thousand-grain volume, DM, EE, and total starch can be used as the key predictors for SID of CP and AA.

Impact of soaking and cooking treatments on the physicochemical and antioxidant properties of parboiled and non-parboiled rice (Oryza sativa L.)

The effects of soaking and cooking on the physicochemical properties and bioactive compounds of two parboiled and non-parboiled rice cultivars (BRRI-28 and Katari bhog) were investigated in this study. Total phenolic content (TPC) increased significantly (p ≤ 0.5) after soaking, while total flavonoid content (TFC) and proanthocyanidin content (PC) decreased significantly (p ≤ 0.5) compared to untreated rice samples. TPC increased by around 23% and 20% in parboiled BRRI 28 and Katari bhog rice extracts, respectively, due to the cooking process, while TFC and PC decreased significantly. DPPH radical scavenging increased whereas reducing power activity decreased after soaking and cooking in parboiled BRRI 28. After processing, the protein, starch, and amylose content of all samples decreased in the majority of cases. After being soaked, all samples L * and b * values increased as compared to raw rice samples. As a result, it can be concluded that the treatment of soaking and cooking of parboiled rice (BRRI-28) was suitable to improve the antioxidant properties as compared to non-parboiled rice.

Insights into Recent Updates on Factors and Technologies That Modulate the Glycemic Index of Rice and Its Products

Rice is a staple food and energy source for half the world's population. Due to its quick digestion and absorption in the gastrointestinal tract, rice is typically regarded as having a high or medium-high glycemic index (GI); however, this can vary depending on the variety, nutrient compositions, processing, and accompanying factors. This report included a table of the glycemic index for rice and rice products in different countries, which could give an overview and fundamental information on the recent GI of different rice varieties. In addition, latest updates about the mechanism effects of rice nutritional profiles and processing techniques on GI were also provided and discussed. The influence of state-of-the-art GI regulation methods was also evaluated. Furthermore, the effectiveness and efficiency of applied technologies were also given. Furthermore, this review offered some aspects about the potential nutraceutical application of rice that food scientists, producers, or consumers might consider. Diverse types of rice are grown under various conditions that could affect the GI of the product. The instinct nutrients in rice could show different effects on the digestion rate of its product. It also revealed that the rice product's digestibility is process-dependent. The postprandial glucose response of the rice products could be changed by modifying processing techniques, which might produce the new less-digestive compound or the inhibition factor in the starch hydrolysis process. Because of the significant importance of rice, this paper also concluded the challenges, as well as some important aspects for future research.

Effect of storage on the nutritional and antioxidant properties of brown Basmati rice

The purpose of the present study is to evaluate the effect of storage time and temperature on the nutritional and antioxidant values of different varieties of brown rice. PARB approved indigenous Basmati varieties (Basmati 86, Basmati 515, Basmati super, Basmati super fine and Basmati kainat) were procured and initially tested for physicochemical parameters, including moisture, ash, lipids, proteins, carbohydrates, and fibers from the brown rice powder. Similarly, antioxidant capacity of these brown rice samples was assessed in terms of total phenolic content and 2,2-diphenyl-1-picrylhydrazyl radical-scavenging potential. Samples of brown rice were stored for 3 and 6 months at 25 and 5°C. On increasing the storage time and temperature, antioxidant activity of rice decreases up to 50%. Nutritional parameters, such as minerals, carbohydrates, and fatty acids were characterized using UV/Vis spectrophotometer, ICP-OES, GC-MS, and HPLC, revealing significant changes in the chemical composition of brown rice. Observation indicates that storage at high temperatures leads to a rapid decrease in carbohydrate and moisture content than at lower temperatures. The protein and ash content remains controlled and integrate with the mineral composition found. Decrease in the glucose and fructose amount was observed in brown rice varieties except for Basmati super fine and Basmati kainat at 5°C. Regarding fatty acids, oleic and linoleic acids were prominent in oils extracted from the different brown rice varieties, and their content was reduced during the storage due to conversion to behenic, and erucic acids, respectively. From the present study, it can be concluded that low storage temperatures reduce the loss of nutrients, offering better nutritional quality for the consumer.

Nutritional and Rheological Characterization of an Infant Flour Based on Parboiled Rice (Oryza sativa), Spirulina (Spirulina platensis), and Cashew Nut (Anacardium occidentale)

Protein-energy malnutrition and mineral deficiencies in children under five years are major problems in developing countries. The present study was thus carried out with the aim of proposing a weaning flour based on parboiled rice, spirulina, and cashew nut that meets the nutritional needs of children aged 06 to 24 months. To achieve this, the mixture design approach (a 9-point augmented simplex-centroid design) was used to obtain optimal blend of flour. The responses evaluated where proteins, lipids, carbohydrates, minerals (iron, calcium, phosphorus, potassium, sodium, magnesium, and zinc), carotenoids, fibers, and ash content. The rheological analyses (rapid viscosity analysis) were carried out on the optimal flour. It results that the optimal proportion of parboiled rice, spirulina, and cashew nut was, respectively, 85.80, 5.96, and 8.23. These conditions result in a protein, lipids, carbohydrates, carotenoids, ash, fibers, calcium, iron, magnesium, and zinc content of 14.15%, 9.04%, 68.46%, 8.2 mg, 3% ash, 4.98%, 510 mg, 16 mg, 65 mg, and 5 mg, respectively, and an energy value of 411.8 kcal. These optimate conditions resulted also in a peak viscosity of 60 cP and a final viscosity of 86 cP which are lower than the established value (1000 cP). Thus, the weaning flour based on parboiled rice, spirulina, and cashew nut obtained in these optimate conditions can meet the nutritional needs of children aged 06 to 24 months and is therefore an efficient weaning food to fight against child malnutrition.

Synergistic effect of microwave heating and hydrothermal treatment on cyanogenic glycosides and bioactive compounds of plum (Prunus domestica L.) kernels: An analytical approach

The effects of microwave heating (450 W for 6 min), hydrothermal treatment (6, 9, and 12 h at 45 °C) and their combination on compositional characteristics, cyanogenic glycosides, color, and bioactive compounds of plum kernels have been studied. The conditions examined caused a significant reduction of 37.81, 72.17, 84.41, 91.24 and 98.02% in cyanogenic glycosides of differently treated plum kernels. Total phenolic and total flavonoid compounds of plum kernels showed hydrothermal time-dependent duration decline. The larger shifts in FT-IR spectra near 1157 cm-¹ provided valuable insights on the reduction of cyanogenic glycosides during combined treatments. The variation of color attributes (L*, a*, b*), during combined treatments indicates a more reddish tonality of plum kernel samples. The combined effect of hydrothermal (12 h at 45 °C) and microwave heating (450 W for 6 min) proved to be an effective tool for neutralizing the toxic effect of cyanogenic glycosides, opening up possibilities for its use in food industries.

•

Hydrothermal and microwave treatments were applied to detoxify plum kernels.

•

The treatments caused highest reduction of 98.02% in cyanogenic glycosides.

•

Combined treatments neutralized the toxic effect of cyanogenic glycosides.

•

FT-IR spectra provided valuable insights on the reduction of cyanogenic glycosides.

Effects of vacuum soaking on the hydration, steaming, and physiochemical properties of japonica rice

Soaking is an essential step in the processing of various rice products. In this study, the influences of vacuum soaking on hydration, steaming, and physiochemical properties of rice were investigated. Results showed that vacuum soaking accelerated water absorption as well as affected the mobility and density of water protons inside rice during soaking. Vacuum soaking could considerably shorten the optimal steaming time from 58 to 32 min and reduce the adhesiveness of steamed rice. Microstructure analysis of rice revealed that porous structure was formed on rice surface and the arrangement of starch granules became loosened after vacuum soaking. Moreover, vacuum soaking slightly reduced the relative crystallinity of rice starches without altering the crystalline type. The gelatinization temperature as well as the peak and trough viscosity was also decreased after vacuum soaking. Our study suggested that vacuum soaking was conducive to improve the soaking and steaming properties of rice.

Impact of processing techniques on the glycemic index of rice

Rice is an important starchy staple food and generally, rice varieties are known to have a higher glycemic index (GI). Over the years, the significance of GI on human health is being better understood and is known to be associated with several lifestyle disorders. Apart from the intrinsic characteristics of rice, different food processing techniques are known to have implications on the GI of rice. This work details the effect of domestic and industrial-level processing techniques on the GI of rice by providing an understanding of the resulting physicochemical changes. An attempt has been made to relate the process-dependent digestion behavior, which in turn reflects on the GI. The role of food constituents is elaborated and the various in vitro and in vivo approaches that have been used to determine the GI of foods are summarized. Considering the broader perspective, the effect of cooking methods and additives is explained. Given the significance of the cereal grain, this work concludes with the challenges and key thrust areas for future research.