Rice Quality Research Articles

Cadmium absorption and translocation in rice plants are influenced by lower air temperatures during grain filling stage

The increasing frequency and severity of low temperatures, and soil cadmium (Cd) pollution threaten food security. However, the interactive effects of Cd exposure and low temperatures on rice yield and quality, as well as the mechanisms of Cd absorption and translocation, remain unclear. In this study, two rice varieties were cultivated in soils with two Cd contamination levels (Cdhigh and Cdlow) and exposed to control (CT25) or lower temperatures of 20 °C (LT20) and 17 °C (LT17) during grain-filling stage. Results showed significant decreases in seed setting rate and grain weight, reduced head rice yield, and increased chalkiness due to low temperatures, particularly in Cdhigh soils. Compared to CT25, LT17 and LT20 increased Cd concentration by 37.6 % and accumulation by 14.8 % in grains grown in Cdhigh soils. Enhanced root activity and upregulation of OsNramp1 and OsNramp5 under both low-temperatures increased Cd levels in roots. Lower temperatures also decreased phytochelatins (PCs) and increased expression of OsHMA2 and OsCAL1, facilitating Cd transport and raising Cd levels in stems. Furthermore, upregulated OsHMA2, OsLCT1, and OsZIP7 in stems under low-temperatures promoted Cd transport to panicles. Overall, low temperatures during grain filling increased Cd uptake and translocation into rice grains, especially in high Cd contaminated soils, raising health risks. The study highlights the need to address climate change's impact on cadmium hazards in rice.

Role of nano-urea in optimizing nitrogen use efficiency, yield and quality of rice: A review

Role of nano-urea in optimizing nitrogen use efficiency, yield and quality of rice: A review

Impact of saline water irrigation on growth, yield and quality of rice (Oryza sativa L.) varieties

Impact of saline water irrigation on growth, yield and quality of rice (Oryza sativa L.) varieties

Effect of cooling rate on the retrogradation properties and quality of refrigerated dry-steamed fried rice

The cooling rate is an important factor affecting the quality of refrigerated fried rice. The effect of the cooling rate (0.16°C/min, 0.78°C/min, 1.66°C/min) on the retrogradation properties of dry-steamed fried rice during the refrigeration period (0-3 d) was investigated. The increased cooling rate from 0.16 to 1.66°C/min led to a weakening of stability of the fried rice gel and an increase in the loss of moisture content of the fried rice from 0.86% to 7.11% after 3 d of refrigeration. The cooling rate of 0.78°C/min slowed the increase in hardness of fried rice and resulted in a lower short-range ordering (0.85) as well as the least increase in relative crystallinity (9.51%) after 3 d of refrigeration. However, a cooling rate of 1.66°C/min resulted in a crispy texture and the worst sensory quality of the fried rice after reheating. Both the 0.16°C/min and the 1.66°C/min cooling rates increased the viscosity and reduced the thermal stability of the fried rice paste system. In contrast, a cooling rate of 0.78°C/min is the most suitable cooling rate for refrigerated dry-steamed fried rice. These results will be of guiding significance for regulating the regrowth of dry-steamed fried rice by changing the cooling rate.

Effect of Grain Coating by Natural Materials on the Aroma Quality of KDML105 Rice

This study evaluated the effectiveness of different coating formulas in preserving the aroma quality of Khao Dawk Mali 105 (KDML 105) rice grains, particularly focusing on the key aroma compound, 2-acetyl-1-pyrroline (2AP). Initially, thirteen coating formulas were tested, and gum arabic was found to be the most effective in maintaining rice appearance and preventing mold growth during storage. In a subsequent experiment, rice coated with carnauba wax, gum arabic, and a 1:1 mixture of both was analyzed for 2AP content over 10 weeks using SHS-GC, under storage conditions of ambient temperature (25 °C) and 4 °C in polyethylene and laminated bags. The 10% gum arabic coating was the most effective at retaining 2AP after 10 weeks. Additionally, the study included a comparison with a 5% rice gel coating and a mixture of 5% gum arabic and 5% rice gel. The results indicated rice stored at 4 °C in laminated bags exhibited a 2-3% reduction in 2AP content after 6 weeks, while at ambient temperature, a reduction of 44-64% was observed. After 10 weeks, the 2AP contents in the 10% gum arabic coated rice were the highest at an average of 38-40% compared to those of the control group. Furthermore, the rancid compounds, including hexanal, heptanal, octanal, nonanal, and 2-pentylfuran, increased significantly in all coated rice samples at ambient temperature, with the highest hexanal content found in rice coated with a mixture of 5% gum arabic and 5% rice gel, showing approximately 22-55% increase compared with those of the uncoated rice. Overall, gum arabic coating was the most effective in preserving 2AP for at least 10 weeks, and storage at 4 °C provided the best conditions for aroma retention and rancid prevention.

Starch lysophospholipids contents affect storage quality of paddy rice

Starch Lysophospholipids (LPLs) have a significant effect on rice grain quality, but how starch LPLs affect paddy rice storage quality is barely understood. The dynamic changes in storage quality indicators of a japonica rice (XS110) and its low LPLs (XS110-J1) and high LPLs (XS110-J2) mutants were investigated. The fatty acid values (FAV) of J1 were significantly higher than those of XS110 and J2 after one year of storage under 24 and 37 °C. Although FAV rose gradually during storage time, it increased relatively more at 37 °C than 24 °C. The malondialdehyde (MDA) content increased significantly in the early stage and decreased gradually during later storage. The MDA content of rice stored at 24 °C was significantly higher than that at 37 °C. The catalase (CAT) activity exhibited a decreasing trend during storage and was relatively higher at 24 °C than 37 °C. The CAT of J2 was significantly higher than those of XS110 and J1. Total lysophospholipid content was relatively stable although some individual LPLs changed significantly during storage. The fatty acid component content in the milled rice decreased during storage, and the content at 37 °C was lower than that at 24 °C. In conclusion, paddy rice with low starch LPLs content is more susceptible to deterioration during storage, suggesting that high starch LPLs can better maintain rice quality and prolong storage time during storage of paddy rice.

Transcriptome analysis of the coexpression network of genes related to antioxidant characteristics after grain filling in purple rice

Antioxidant capacity is an important indicator for evaluating the growth and developmental quality of rice. This study has guiding significance for the cultivation of high-nutrient-value varieties. To investigate the molecular mechanisms underlying the antioxidant characteristics of rice grains after the filling stage, Yangzinuo 1 (YZN1) was used as the experimental material, and grains collected at five different time points (7 days apart) after the filling stage were used for transcriptome sequencing. Through weighted gene coexpression network analysis (WGCNA), a coexpression network of gene weights related to antioxidant characteristics was constructed. LOC_Os10g39140, LOC_Os10g38276, and LOC_Os05g45740 were identified from the 2 modules showing the highest correlations with the target traits. GO functional annotation showed that target modules were enriched in pathways related to phenylalanine, flavonoids, and other related pathways, such as GO:0006558, GO:0006559, GO:0009812, and GO:0009813. Correlation analysis with metabolites revealed that differentially expressed genes were significantly enriched in pathways related to antioxidant characteristics and energy metabolism processes, such as glycolysis/gluconeogenesis and flavonoid biosynthesis. The core genes identified in this study were found to be highly correlated with antioxidant characteristics and enriched in pathways related to metabolic and energy pathways and molecular activities. These results provide an effective dataset supporting breeding targeting functional rice characteristics.

Grain Appearance Quality of Parental and \(F_2\) Segregating Populations of Aus Rice (Oryza sativa L.)

Longer grain length with smaller grain breadth, length-breadth ratio and 1000-grain weight is considered desirable character for the development of fine grain premium quality rice. In the present experiment, grain appearance quality of 15 F2 families and 10 parental genotypes were determined to select fine grain rice. The maximum mean value for thousand seed weight was found from the genotypes P2 (29.32g), P1 (28.89g), and F2 generations of P2 x P5 (32.77g), P2 x P1 (27.30g), P1 x P4 (26.04g) and were considered as high yielders in terms of grain weight. The highest mean values for grain length were found from the genotypes P6 (9.95 mm; grain breadth 2.23 mm), P7 (9.36 mm; grain breadth 2.62 mm), and F2 generations of P6 x P7 (9.46 mm; grain breadth 2.44 mm), P3 x P6 (9.40 mm; grain breadth 2.18 mm), P7 x P6 (9.37 mm; grain breadth 2.29 mm), P7 x P3 (9.36 mm; grain breadth 2.33 mm). The F2 progenies of the cross P1 x P4 (7.79 to 11.61 mm) and P6 x P3 (7.69 to 11.11 mm) showed extremes performance for grain length indicating transgressive segregation for this trait. The superior genotypes with desirable grain characters could be selected from transgressive segregation of F2 families for the development of new varieties of fine grain rice.

Pyramid-YOLOv8: a detection algorithm for precise detection of rice leaf blast

Rice blast is the primary disease affecting rice yield and quality, and its effective detection is essential to ensure rice yield and promote sustainable agricultural production. To address traditional disease detection methods’ time-consuming and inefficient nature, we proposed a method called Pyramid-YOLOv8 for rapid and accurate rice leaf blast disease detection in this study. The algorithm is built on the YOLOv8x network framework and features a multi-attention feature fusion network structure. This structure enhances the original feature pyramid structure and works with an additional detection head for improved performance. Additionally, this study designs a lightweight C2F-Pyramid module to enhance the model’s computational efficiency. In the comparison experiments, Pyramid-YOLOv8 shows excellent performance with a mean Average Precision (mAP) of 84.3%, which is an improvement of 9.9%, 4.3%, 7.4%, 6.1%, 1.5%, 3.7%, and 8.2% compared to the models Faster-RCNN, RT-DETR, YOLOv3-SPP, YOLOv5x, YOLOv9e, and YOLOv10x, respectively. Additionally, it reaches a detection speed of 62.5 FPS; the model comprises only 42.0 M parameters. Meanwhile, the model size and Floating Point Operations (FLOPs) are reduced by 41.7% and 23.8%, respectively. These results demonstrate the high efficiency of Pyramid-YOLOv8 in detecting rice leaf blast. In summary, the Pyramid-YOLOv8 algorithm developed in this study offers a robust theoretical foundation for rice disease detection and introduces a new perspective on disease management and prevention strategies in agricultural production.

Decorated-Induced Oxygen Vacancy Engineering for Ultra-Low Concentration Nonanal Sensing: A Case Study of La-Decorated Bi2O2CO3.

La-decorated Bi2O2CO3 (BCO-La) microspheres are synthesized using a facile wet chemical strategy for sensing low-concentration nonanal (C9H18O) at room temperature. These BCO-La gas sensors are applied to evaluate agricultural product quality, specifically for cooked rice. The sensitivity of the BCO-6La sensor significantly surpassed that of the pure BCO sensor, achieving a response value of 174.6 when detecting 30ppm nonanal gas. Notably, the BCO-6La sensor demonstrated a faster response time (36 s) when exposed to 18ppm of nonanal. Additionally, the selectivity toward nonanal gas detection is higher (approximately 4-24 times) compared to interfering gases (1-octanol, geranyl acetone, linalool, hexanal, 2-pentyfuran, and 1-octen-3-ol) during cooked rice quality detection. The gas sensing mechanism and the factors contributing to the enhanced sensing performance of the BCO-La microspheres are demonstrated through in situ FT-IR spectra and DFT analysis while the realistic detection scenario is carried out. In a broader context, the reported sensors here represent a novel platform for the detection and monitoring of gases released by agricultural products during storage.

Effects of Low Field Temperature on the Physicochemical Properties and Fine Structure Stability of High-Quality Rice Starch during the Grain Filling Stage.

The consumption of high-quality rice is increasing. Low temperatures during grain filling may affect the starch synthesis of high-quality rice and thus affect the quality of the rice itself. In this study, two high-quality conventional rice cultivars and two high-quality hybrid rice cultivars were selected and sown at a low temperature and normal temperature in the field. The low temperature during grain filling increased the amylose content, final viscosity, setback, short amylopectin chain ratio, and degree of amylopectin branching in four high-quality rice cultivars; meanwhile, the amylopectin content, gelatinization temperature, proportion of medium-long chain amylopectin, and the short-range order of starch decreased. Compared with the normal temperature, the alterations in the physicochemical and structural qualities of high-quality conventional rice cultivars YZX and NX42 were less significant at lower temperatures. The starch quality of high-quality conventional rice was more stable than hybrid high-quality rice.

Electronic nose combines an effective deep learning method to identify the rice quality under different storage conditions and storage periods

Temperature is a key factor affecting the rice quality during storage, and an effective method to detect the rice quality during storage period is crucial. Gas information is an intuitive reflection of changes in rice quality. In this work, a deep learning algorithm, combined with an electronic nose (e-nose), provides a rapid detection method for rice quality. First, using a PEN3 e-nose system, gas information from rice stored under two different temperatures and periods is collected. Second, a Multi-branch Self-attention Module (MSAM) is proposed to focus on important gas features, enhancing the e-nose's classification performance. Third, MSAM-Net is established to identify the rice gas information under various storage conditions and periods. Ablation analysis and comparisons with state-of-the-art gas classification methods show that MSAM-Net delivers superior performance. At a temperature of 25 ℃ and a relative humidity of 35RH %, MSAM-Net achieves an accuracy of 96.25% and an F1-score of 96.84%. At a temperature of 40 ℃ and a relative humidity of 35 RH%, MSAM-Net achieves an accuracy of 97.42% and an F1-score of 97.64%. In summary, the combination of artificial intelligence and gas sensing provides an effective technical approach for rice quality detection.

Improvement of Quality and Disease Resistance for a Heavy-Panicle Hybrid Restorer Line, R600, in Rice (Oryza sativa L.) by Gene Pyramiding Breeding.

The utilization of heavy-panicle hybrid rice exemplifies the successful integration of architectural enhancement and heterosis, which has been widely adopted in the southwest rice-producing area of China. Iterative improvement in disease resistance and grain quality of heavy-panicle hybrid rice varieties is crucial to promote their sustainable utilization. Here, we performed a molecular design breeding strategy to introgress beneficial alleles of broad-spectrum disease resistance and grain quality into a heavy-panicle hybrid backbone restorer line Shuhui 600 (R600). We successfully developed introgression lines through marker-assisted selection to pyramid major genes (Wxb + ALKA-GC + Pigm + Xa23) derived from three parents (Huanghuazhan, I135, I488), which significantly enhance grain quality and confer resistance to rice blast and bacterial blight (BB). The improved parental R600 line (iR600) exhibited superior grain quality and elevated disease resistance while maintaining the heavy-panicle architecture and high-yield capacity of R600. Moreover, the iR600 was crossed with male sterility line 608A to obtain a new heavy-panicle hybrid rice variety with excellent eating and cooking quality (ECQ) and high yield potential. This study presents an effective breeding strategy for rice breeders to expedite the improvement of grain quality and disease resistance in heavy-panicle hybrid rice.

Surfactins and Iturins Produced by Bacillus velezensis Jt84 Strain Synergistically Contribute to the Biocontrol of Rice False Smut

Rice false smut, caused by the plant pathogenic fungus Ustilaginoidea virens, is widespread in rice-growing regions globally, severely compromising rice quality and production. Employing Bacillus spp. to control rice false smut represents an effective and environmentally sustainable strategy for disease management. The lipopeptides produced by Bacillus velezensis Jt84 demonstrated robust inhibitory effects against U. virens, resulting in abnormal mycelial morphology and spore germination. Iturins were identified as essential for the antifungal activity against U. virens, as confirmed by mutagenesis experiments that suppressed iturin biosynthesis. The surfactin-deficient mutant exhibited inhibitory effects against U. virens comparable to the wild-type, indicating that the absence of surfactins did not diminish its antifungal activity. Both the Jt84∆srf and Jt84∆itu mutants displayed reduced biofilm formation capabilities compared to the wild-type, with the Jt84∆srf mutant being particularly impaired and unable to form a complete biofilm. Regarding swarming motility, the ∆srf mutant exhibited a significant reduction compared to the wild-type, whereas the Jt84∆itu mutant showed a modest increase. Colonization experiments revealed that the Jt84∆srf mutant strain had significantly lower colonization on rice leaf surfaces than the wild-type strain, highlighting the critical role of surfactins in the colonization of B. velezensis Jt84 on rice leaves. In conclusion, our research demonstrated that surfactins and iturins have distinct functionalities and act synergistically to contribute to the biocontrol of rice false smut in B. velezensis Jt84. This synergy is achieved through their potent antifungal effects, biofilm formation, and successful colonization.

Physicochemical and Morphological Changes in Long-Grain Brown Rice Milling: A Study Using Image Visualization Technologies

This study evaluated the changes in physicochemical properties and appearance quality of long-grain rice during the grinding process using image technologies and aimed to provide reference for future research. The brown rice milling process was divided into three stages, and flatbed scanning, scanning electron microscopy (SEM), X-ray micro-computed tomography (micro-CT), low-field nuclear magic resonance (LF-NMR), and headspace–gas chromatography–ion mobility spectrometry (HS–GC–IMS) were employed to examine the physicochemical and volatile properties of the samples. Results revealed a continuous increase in the degree of milling, with a broken rice rate and a whiteness value increasing by 50.84% and 21.13%, respectively, compared with those during the initial stage; dietary fiber and vitamin B1 contents were reduced by 54.41% and 66.67%, respectively. The image results visualized showed that the cortex of brown rice was gradually peeled off with the increase in milling degree; the cortical thickness was gradually reduced, the endosperm was gradually exposed, and the surface was smoother and shinier. T2 populations exhibited a shift toward longer relaxation times, followed by a decrease in relaxation time during the milling process. Additionally, 31 target compounds impacting rice flavor, mainly ketones, alcohols, and esters, were identified, and the concentration of volatile substances in the B region decreased with the reduction in the bran layer; the concentration of volatile substances in the C region provided rice flavor, which increased with the milling process. This study showed changes in the physicochemical properties and appearance quality of long-grain brown rice during milling. Furthermore, the use of various image processing techniques offers significant insights for optimizing processing parameters and enhancing overall quality and taste.

Variation in Starch Properties in Ratoon Rice and Their Relationship with Rice Quality

Ratoon rice is characterized by higher production combined with enhanced rice quality. However, the relationship between the differences in the structure and properties of the starch and variations in the ratoon season and rice quality is still unclear. In this study, we conducted a field experiment in 2023 to assess the relationship between rice quality differences and starch characteristics of four different hybrid rice varieties (Longjingyou1212: LJY1212; Taoyouxiangzhan: TYXZ; Liangyou6326: LY6326; Fengliangyouxiang1: FLYX1) in the ratoon season. In terms of appearance, the chalkiness degrees and chalky grain percentage of LJY1212 (0.6%, 2.3%) and TYXZ (1.2%, 6.0%) were 53.5% and 53.9% lower than those of LY6326 (2.4%, 10.0%) and FLYX1 (1.6%, 7.8%), indicating that the appearances of LJY1212 and TYXZ were better than those of LY6326 and FLYX1. The average amylose contents of LJY1212 (18.5%) and TYXZ (19.0%) were 10.8% higher than those of LY6326 (17.7%) and FLYX1 (15.7%), and there was no significant difference in protein content between the varieties in the ratoon season. Regarding the starch microstructure, the starch granules of LJY1212 and TYXZ in the ratoon season were arranged more closely. The average ratios of 1045/1022 cm−1 of LJY1212 (0.77) and TYXZ (0.76) were 7.0% higher than those of LY6326 (0.71) and FLYX1 (0.72), indicating that the internal orders of LJY1212 and TYXZ’s starch were better than those of LY6326 and FLYX1. The average relative crystallinities of LJY1212 (24.8%) and TYXZ (24.5%) were 5.2% lower than those of LY6326 (25.7%) and FLYX1 (26.6%). The relative crystallinity of starch decreased with the increase in amylose content, while the short-range order degree, gelatinization temperature, and gelatinization enthalpy increased with the increase in amylose content. Therefore, the LJY1212 and TYXZ varieties, with better rice qualities, are recommended for planting in southern China.

Sodium alumino silicate (SAS) neem nanocomposite – A novel seed storage tool against toxigenic Aspergillus flavus causing deterimental effects on seeds health and quality of rice

Infection of rice grains in the field during harvest and storage by Aspergillus flavus, a toxigenic mold causes significant losses to market acceptability of seeds due to its detrimental effects on seed health and quality parameters. Production of aflatoxin by A. flavus interferes with physiological factors affecting the quality of seeds during storage in addition to nutritional losses to the grains. Chemical seed treatments are generally not recommended during storage due to their adverse effects on seed germination and vigor. Leaves of the neem tree (Azadirachta indica) are well known for antifungal properties against phytopathogenic fungi such as A. flavus. The paper presents the effect of neem leaf extract adsorbed onto sodium alumino-silicate (SAS) nanoparticles against A. flavus in rice seeds during storage. SAS-Neem nanocomposite, a novel unexplored seed storage material against toxigenic A. flavus, was synthesized for augmented antitoxin and seed invigorating potential. The nanocomposite was characterized using an array of microscopic and spectroscopic methods to evaluate the adsorption of neem leaf extract components on SAS nanoparticles. The antifungal mechanism of the nanocomposite was evaluated via scanning electron microscope, phase contrast, and fluorescence microscopy. The toxin analysis of pathogen-inoculated seeds was carried out at monthly intervals for 6 months during storage of two rice varieties, i.e. PR114 and Pusa-Basmati 1121. The results indicated that the nSAS-Neem composite used as seed coating material maintained significantly higher seed germination (86.23 and 81.49%) and minimized seed rot (6.70 and 5.30%, respectively) in the two varieties under study than the control after 6 months of storage. There was a notable decrease in toxin concentration from 20.58 to 11.19 μg/kg and 19.16 to 12.58 μg/kg in seeds of the two varieties i.e. PR114 and Pusa Basmati 1121, respectively. The nano-composite proved effective against toxigenic A. flavus during seed storage of rice without compromising the seed quality parameters.

Reduced Nitrogen Application with Dense Planting Achieves High Eating Quality and Stable Yield of Rice.

Rational nitrogen (N) application can enhance yield and improve grain eating quality in rice. However, excessive N input can deteriorate grain eating quality and aggravate environmental pollution, while reduced N application (RN) decreases rice yield. Reduced N application with dense planting (RNDP) is recommended for maintaining rice yield and improving N use efficiency. However, the effects of RNDP on the rice grain eating quality and starch structure and properties remain unclear. A two-year field experiment was conducted to investigate the effects of RNDP on the rice yield, grain eating quality, and starch structure and properties. Compared to conventional N treatment, RN decreased significantly the rice yield, while RNDP achieved a comparable grain yield. Both the RN and RNDP treatments improved significantly the rice eating quality. The high eating quality of RNDP was attributed to increased gel consistency, pasting viscosity, and stickiness after cooking as well as decreased protein content. A further analysis of starch structure and properties revealed that RNDP decreased the relative crystallinity, lamellar intensity, gelatinization enthalpy, and retrogradation enthalpy of starch. Therefore, RNDP achieved a stable rice yield and enhanced rice eating quality. These findings provide valuable insights into obtaining optimal quality and consistent yield in rice production under reduced N conditions.

Optimization of High-Pressure Processing for Microbial Inactivation in Pigmented Rice Grass Juice and Quality Impact Assessment during Refrigerated Storage.

Pigmented rice grass juice (RGJ) is a good source of bioactive compounds, but fresh juice has a relatively short shelf life of only 7 days at 4 °C. The objectives of this study were to determine the optimal growth stage of pigmented rice grass, investigate the optimal condition of high-pressure processing (HPP) for bacterial inactivation in inoculated RGJ using response surface methodology (RSM), and evaluate quality changes in uninoculated HPP-treated juice during storage at 4 °C compared with heat-treated (85 °C/10 min) and untreated samples. Results revealed that the optimal growth stage of rice grass was 9 days with the highest total anthocyanin content of 158.92 mg/L. The optimal condition of HPP was determined to be 612 MPa, 11 min, and 36 °C, and inactivated Escherichia coli K12 and Listeria innocua with 6.43 and 5.02 log reductions, respectively, meeting FDA regulations. The lethality of bacteria after HPP treatment can be explained by damage to the cell membrane and the leakage of intracellular constituents such as protein and nucleic acid. During 12 weeks of storage at 4 °C, total plate counts and yeast and mold counts in uninoculated HPP-treated juice were not detected. Moreover, HPP did not significantly change phytochemical properties (p < 0.05), caused a minor impact on physicochemical properties of RGJ, and maintained the durability of juice samples during storage. Analysis of the phytochemical profile revealed that HPP treatment could preserve most of the phenolic compounds in RGJ and especially increase the contents of protocatechuic acid, 4-hydroxybenzoic acid, syringic acid, transcinnamic acid, isorhamnetin-3-o-glucoside, quercetin, and cyanidin-3-glucoside (p < 0.05). Overall, HPP is a potential pasteurization technique for microbial inactivation and nutritional preservation for rice grass juice.

Changes in Quality Characteristics and Metabolite Composition of Low-Temperature and Nitrogen-Modified Atmosphere in Indica Rice during Storage.

A low temperature (LT) is used to delay grain deterioration effectively. In practical applications, a nitrogen-modified atmosphere (N2) is also an effective way of preventing grain pests and delaying grain deterioration. However, there are few studies on grain quality changes using a combination treatment of an LT and N2 during storage. In this study, the storage quality, processing characteristics, and metabolites of rice under conventional storage (CS), LT (20 °C), N2 (95%), and LT+N2 treatments were analyzed for 180 days, under a controlled humidity of 65% ± 2%. The results showed that compared to the CS, LT, and N2 treatments, the LT+N2 treatment had the best effect in retarding the increase in MDA and electrical conductivity and deferring the decrease in CAT activity. In addition, the LT+N2 treatment maintained the color of the rice better and sustained a better processing quality. Non-targeted metabolomics analysis further confirmed that the LT+N2 treatment maintained the vigor of the rice and retarded its spoilage by activating the metabolisms of amino acids, carbohydrates, and flavonoids. These results suggest a favorable practice for preventing storage deterioration and increasing the processing quality for rice storage. They provided new insights into the mechanisms of rice quality changes using the combination treatment of an LT and N2.