Milling degree affects the fermentation properties of rice:perspectives from the composition of nutrients and gut microbiota via in vitro fermentation

Fermentation substrates of rice with different milling degrees(MDs) were prepared and fermented with human feces to compare their fermentation properties and effects on gut microbiota.MD 0s,MD 5s and MD 60s represented brown rice,moderately-milled rice and white rice,respectively.After in vitro fermentation,the MD 5s group showed higher starch utilization,compared with the MD 0s and 60s groups evaluated by Fourier transform infrared spectrometer,and confocal laser scanning microscope.Effects of fermentation substrates of rice with different MDs on gut microbiota were evaluated by 16S rDNA sequencing.All the sample groups reduced the pH and produced short-chain fatty acids(SCFAs) and branched-chain fatty acids.The MD 5s group exhibited higher α-diversity than the MD 0s and 60s groups.Abundances of Phascolarctobacterium,Blautia and norank_f_Ruminococcaceae were higher in the MD 0s and 5s groups,compared with the MD 60s group.These bacteria were also positively correlated with the SCFAs production via Spearman correlation analysis.In vitro culture assay revealed that fermentation substrates of MD 0s and 5s promoted the growth of two probiotics(Akkermansia muciniphila and Bifidobacterium adolescentis).Our results showed that moderate milling might be an appropriate way to produce rice products with richer nutrients and better fermentation properties.

Rice Drying,Storage and Processing:Effects of Post-Harvest Operations on Grain Quality

Various post-harvest processes of rice are commonly employed,especially during the off-season,to ensure its consumption feasibility,which often affect the grain quality.Different forms of drying,storage and processing of rice are evaluated to identify their effects on grain quality.Microwave drying has emerged as an alternative to the widely-used intermittent-drying and fixed-bed-dryer methods of drying paddy rice.Control of drying-air temperatures(between 40℃ and 60℃)according to the rice variety can improve quality,especially for exotic varieties.Keeping stored grain in hygroscopic balance,with water content between 11%to 15%,at temperatures between 16℃ and 20℃ and with intergranular relative humidity near 60%,allows 12 months of storage in a controlled environment without significant deterioration.Other innovations,notably the application of artificial refrigeration to grain stored in bulk in vertical cylindrical silos and the use of impermeable packaging for storage,ensure the conservation of grain mass.The different stages and equipments used to obtain polished,brown and parboiled rice result in significant changes in the nutritional value of rice because of the removal of the outermost layers of the grains.Polishing reduces the nutritional value and physical homogeneity of rice.Brown rice retains more bioactive compounds and nutrients because it does not lose the outer layer of the grains in the polishing processes.Parboiled rice,although less nutritious than brown rice,has better grain integrity and milling yield and less loss of nutrients than white rice.

Varietal and Seasonal Effect of Rice on the Physicochemical Properties of Rice Flakes

Rice-based flakes made from 7 mid-season rice varieties （4 indica and 3 japonica subspecies） and 3 early season indica varieties produced both in early and late season were studied for their main physicochemical characters, including water activity, film thickness, bulk density （BD）, ash, reducing sugars （RS）, protein, phytic acid, starch, amylose, and rapid visco analyser （RVA） viscosity profile. A significant varietal effect was found for all these parameters （P〈 0.05 or 0.01） except starch. Strong variety x season interactions were observed but the seasonal effect was less pronounced, and only significant （P〈0.01） for RS. The apparent amylose content （AAC） office flakes was significantly correlated （P〈0.01） with AAC （r=0.99） and several RVA profile parameters [e.g., final viscosity （r=0.92）] of rice flour. For rice flakes, BD was significantly correlated with AAC （r=0.82, P〈0.01） and most RVA profile parameters. The study indicates that varietal and environmental effects should be considered simultaneously for optimal production of rice grains for rice flakes manufacturing.

Calcium effect on the process of cold-hardening of rice seedlings

Low temperature is an important environmen-tal factor that limits the productivity and dis-tribution of plant. The ability to cold acclima-tion is a common adaptive response in plantsnative in temperate regions and results in en-hancing tolerance to chilling stress. In presentstudy the seedlings of Tesanai 2 were grown at28±1℃ and under a photo flux density (PFD)of 30μmol/m~2s for 8 d. The cold acclimationresponse is triggered by 14℃ under a PFD of75 μmol/m~2s for 3 d. Rice seedlings for cold-hardening were germinated from seeds treatedwith or without immersion in 30 mmol/L ofCaClsolution. Change of membrane systemprotection in leaves at various periods(viz:fol-lowing cold-hardening, chilling stress and onthe 3rd day of recovery), the ratio of survival

Construction and modification of chloroplast ultrastructure of a special albino rice mutant W25 during the seedling greenish process

W25 was a gamma-irradiation induced albinorice mutant line, which only expressed in thespecial temperatures (see figure). At 30 Cand 35 C, the seedling leaves of W25 showedgreenish or normal green, but they exhibitedalbino at 25℃, which could be greenish afterthe fourth leaf extension and recovered to be