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Abstract: The objective of this study was to accelerate the aging of “Thai jasmine” paddy via the use of a drying process, which consists of high-temperature fluidized bed drying followed by tempering and ventilation. Based on the experimental results it was found that the rice properties after processing, namely, elongation ratio, whiteness, volume expansion, water uptake, solids loss and pasting properties, changed in a similar fashion to those of the naturally aged paddy. The higher drying temperature, higher initial moisture content and longer tempering time significantly affected the aged rice properties. However, the head rice yield of rice undergone thermal processing was significantly lower than that of the naturally aged paddy. The drying temperature of 150°C, initial moisture content of 33% (d.b.) and tempering time of at least 90min were recommended as the most suitable conditions for accelerating the rice aging process. [Copyright &y& Elsevier]

Abstract: This research is a study of parboiling of brown rice using superheated steam fluidization technique. The influence of soaking temperature and time, steaming temperature, and bed depth on qualities of product: head rice yield, white belly, whiteness, and viscosity of rice flour were focused. The experiments were set up at the material initial moisture content of 12.8% dry basis (d.b.), soaking temperatures of 70–90°C, soaking times of 0.5–2.0h., steaming temperatures of 120–160°C, velocity of 3.9m/s and bed depths of 8–12cm. The experimental result showed that gelatinization occurred while product moisture content decreased and final moisture content about 28% d.b. gave the acceptable levels of the whiteness and white belly. The final moisture content lower than 28% and 18% d.b. resulted in the lower percent of head rice yield and whiteness, respectively. Considering white belly, it was found that the white belly decreased with increasing drying time. Additionally, peak viscosity, breakdown viscosity and setback viscosity of rice flour were found lower than those of raw rice. [Copyright &y& Elsevier]

The effects of drying methods and storage time on the aroma and milling quality of the aromatic rice, Khao Dawk Mali 105, stored as whole grains, were investigated in order to define the most appropriate post-harvest treatment for the rice. Among the six drying methods that were used, namely: modified air at 30 and 40 °C, hot air at 40, 50, and 70 °C, and sun-drying, the methods that employed lower temperature appeared to provide higher concentrations of the key aroma compound, 2-acetyl-1-pyrroline, and lower amounts of the off-flavour compounds, n-hexanal and 2-pentylfuran, regardless of the storage time. The sun-drying method yielded contrasting results. Overall, during 10 months storage, as the time increased, 2-acetyl-1-pyrroline concentrations decreased whereas n-hexanal and 2-pentylfuran contents increased. Head rice yield was most clearly affected in the sample dried by hot air at 70 °C, giving a percentage yield slightly less than half of those obtained by the other drying methods. However, no significant variation in the percentages of whiteness was observed among the rice samples obtained from the different drying methods and storage times. [Copyright &y& Elsevier]

A method was developed for the determination of the size and size distribution of rice and the amount of broken rice kernels using flatbed scanning (FBS) and image analysis (IA). The rice was placed on the glass plate of the scanner and covered with a black sheet of paper. A fully automatic procedure was developed using freeware IA software and standard spreadsheet software. The method was tested on parboiled and regular-milled white rice of different varieties and compared to manual analysis by weighing after visual separation of whole and broken kernels and by measuring the length and width of rice kernels using a sliding calliper. The FBS method is fast, easy to use and cheap. It yields the same accuracy and better precision than the more time-consuming manual method. Analysis by FBS-IA takes about 3 min per sample compared to about 30 min for manual analysis. The procedure requires a PC with standard desktop scanner. [Copyright &y& Elsevier]

Fluidised bed paddy drying using superheated steam is a newly alternative approach instead of using the conventional hot air. The mechanism of mass transfer for paddy drying in a range of initial moisture content between 25% and 44.5% d.b. is strongly controlled by internal moisture movement inside the kernel and a two-series exponential equation is suitably used to explain its movement. Drying parameters in the equation are a function of temperature and bed depth. For the paddy quality, head rice yield from the superheated steam drying is more sustainable and has higher values than those obtained from the hot air drying, whereas the colour of white rice becomes darker, making it poorer quality. The percentage of white belly is significantly affected by the initial moisture content. [Copyright &y& Elsevier]

[Display omitted] • High-quality cultivar has higher rice quality in dry cultivation in ratoon season. • The accumulation of fatty acids and amino acids assists the rice quality. • Formation of amylopectin optimize crystallites traits to improve rice quality. • The main or diversity of functional groups support rice quality. A field experiment was conducted to explore the impact on rice quality using high-quality (HH) or drought-resistant (HY) cultivars under flooding irrigation (F) or dry cultivation (D) in ratooning rice system by evaluating the metabolism or physicochemical traits of starch, fatty acids, and amino acids affecting grain quality. Compared to FHY and DHY in the main or ratoon season, DHH in ratoon season (DHHR) exhibited a higher appearance and processing quality but lower cooking quality. DHHR mainly synthesized long branch chain amylopectin to construct the crystalline regions with increased crystallinity, crystallites size, interplanar spacing, dislocation density, Asp and Thr in brown and head rice. Also, it accumulated more of C16:0, C18:0, C18:1, C18:2, and C18:3 but reduced glutelin in head rice. An increase in functional groups and diversity was seen in brown and head rice, respectively. Overall, these traits improved the processing, appearance, and pasting quality of DHHR. [ABSTRACT FROM AUTHOR]

A pot experiment was conducted to explore the effects of high-quality (Huanghuazhan, HH), drought-resistant (IR, IRAT109) and drought-susceptible cultivars (ZS, Zhenshan97) under flooding irrigation and dry cultivation (D) on the starch accumulation and synthesis, physicochemical traits of starch granules and rice grain quality at the upper (U) and lower panicle. Under D treatment, IR and ZS had lower rice quality, especially the appearance and cooking quality. DHH-U had the highest appearance, nutritional and cooking quality among all cultivars under D treatment, which could be ascribed to the synthesis of more short-branch chain amylopectin and correspondingly higher starch granule tightness. DHH-U also maintained ordered carbohydrate structure, crystalline regions, and many hydrophilic and hydrophobic functional groups in starch granules before pasting. It could prevent the polymerization of small molecules to avoid the formation of macromolecules after pasting. Overall, these findings may facilitate the improvement of grain quality in rice dry cultivation. • High-quality cultivar outperforms other cultivars in grain quality in dry cultivation. • Formation of short-branched chains of amyplopectin improves rice quality. • Rice dry cultivation leads to highly ordered and crystalline starch granules. • Hydrophilic and hydrophobic functional groups affect rice quality. [ABSTRACT FROM AUTHOR]

Brown rice of different long-grain Indica cultivars was polished to variable degree of milling (DoM) to see the difference in proteins and starches characteristics in head (HR) and broken rice (BR). Study revealed differential accumulation of starch, fat and proteins in both HR and BR. Extended DoM of brown rice resulted in a progressive decrease in HR yield and increase in BR yield. The extended DoM caused a decrease in protein and fat content in both HR and BR, whereas; an increase in peak viscosity and final viscosity was observed. On the contrary, the setback viscosity of HR and BR of different rice cultivars was influenced by cultivars and extended DoM. Milled rice from different cultivars milled to 6% DoM showed higher levels of 59 kDa, 54 kDa, 51 kDa, 32 kDa, 31 kDa, 30 kDa, 28 kDa, 24 kDa, 23 kDa, 15 kDa, 13 and 12 kDa PPs, while 28 kDa, 24 kDa, 23 kDa, 15 kDa, 13 kDa and 12 kDa PPs was the least or not observed in BR. The major quantitative changes were observed in 28 kDa, 24 kDa, and 23 kDa PPs. MALDI-ToF/MS analysis revealed the identity of 28 kDa PP as 60S ribosomal protein L10a and glutelin type-D 1 proteins. Whereas, the identity of 24 and 23 kDa PP, respectively was established as pathogenesis-related protein 1 (Oryza sativa Japonica Group) and Oryza sativa 1-Cys peroxiredoxin A. HR showed the presence of highly condensed packaged starch granules with smooth edges, which were tightly imbibed in the proteins matrix. However, the inter-cultivar differences in the starch structure and packaging were also observed. On the contrary, BR revealed lesser accumulation of starch particles with abnormal protein filling and several fissures and cracks in the starch granules of BR of different cultivars. A graphical abstract showing differences in head and broken rice of different long grain Indica rice cultivars. The differences in the protein profile and internal starch granule structure, imbibed in protein matrix, are visible from SDS-PAGE and field emission scanning electron microscopic analysis. Unlabelled Image • Head rice yield decreased with the extended degree of milling (DoM). • Extended DoM caused a decrease in protein content, fat content in both head rice (HR) and broken rice (BR). • Peak viscosity and final viscosity of HR and BR was increased with extended DoM. • MALDI-ToF/MS analysis revealed the absence or least accumulation of glutelin type-D 1 protein in BR. • Storage of 60S ribosomal protein L10a, pathogenesis-related protein 1 and 1-Cys peroxiredoxin A was varied in HR and BR of different cultivars. [ABSTRACT FROM AUTHOR]