Yield, Grain Quality, and Starch Physicochemical Properties of 2 Elite Thai Rice Cultivars Grown under Varying Production Systems and Soil Characteristics

Abstract

Rice production systems and soil characteristics play a crucial role in determining its yield and grain quality. Two elite Thai rice cultivars, namely, KDML105 and RD6, were cultivated in two production systems with distinct soil characteristics, including net-house pot production and open-field production. Under open-field system, KDML105 and RD6 had greater panicle number, total grain weight, 100-grain weight, grain size, and dimension than those grown in the net-house. The amounts of reducing sugar and long amylopectin branch chains (DP 25–36) of the RD6 grains along with the amounts of long branch chains (DP 25–36 and DP ≥ 37), C-type starch granules, and average chain length of the KDML105 were substantially enhanced by the open-field cultivation. Contrastingly, the relative crystallinity of RD6 starch and the amounts of short branch chains (DP 6–12 and DP 13–24), B- and A-type granules, and median granule size of KDML105 starch were significantly suppressed. Consequently, the open-field-grown RD6 starch displayed significant changes in its gelatinization and retrogradation properties, whereas, certain retrogradation parameters and peak viscosity (PV) of KDML105 starches were differentially affected by the distinct cultivating conditions. This study demonstrated the influences of production systems and soil characteristics on the physicochemical properties of rice starches.

Application of Two-Stage Variable Temperature Drying in Hot Air-Drying of Paddy Rice

“…The separation of starch adopted the alkaline extraction method [ 22 ]. According to the method of Dawei Zhu et al [ 21 ], starch was extracted from rice flour which passed through a 100-mesh sieve.…”

Starch Chemical Composition and Molecular Structure in Relation to Physicochemical Characteristics and Resistant Starch Content of Four Thai Commercial Rice Cultivars Differing in Pasting Properties

“…Rice starch is one of the world’s most important sources of food energy [ 1 ]. In Thailand, rice grains are the major food and give the most caloric intake for 70.08 million individuals [ 2 , 3 ]. Currently, rice starches isolated from Thai rice grains are widely used as biopolymers in the beverages, bakery, pharmaceutical and supplement, cosmetic, animal feed, paper making, adhesive, and textile industries [ 4 , 5 ].…”

“…In 2021, starch-rich food and non-food products from Thai commercial rice cultivars were exported to the world market, providing about USD 4087 million in income for the country [ 6 ]. The extensive industrial applications of Thai commercial rice starches are due to their great variations in molecular compositions and structures (i.e., amylose and protein contents, amylose–lipid complex, chain length distribution (CLD) of amylopectin, average chain length (CL), degree of polymerization, granule size, and granule crystallinity) [ 2 , 5 , 7 , 8 , 9 ]. These are critical determinants for their diversities in non-resistant and resistant starch (RS) contents and physicochemical properties (e.g., swelling, solubility, thermal properties, and pasting properties) [ 2 , 8 , 10 , 11 , 12 ].…”

“…Consequently, the amylopectin double helices that are packed in an ordered structure primarily contribute to the formation of the crystallinity of starch granules [ 13 ]. Longer starch chains would form long or strong single and double helices through intra- and intermolecular hydrogen bonds between chains, spanning the complete crystalline structures [ 2 , 8 , 9 , 10 , 14 , 15 ]. In contrast, the presence of shorter starch chains would produce shorter or weaker single and double helices, resulting in inferior crystalline structures within the granules [ 2 , 8 , 9 , 10 , 14 , 15 ].…”

“…Longer starch chains would form long or strong single and double helices through intra- and intermolecular hydrogen bonds between chains, spanning the complete crystalline structures [ 2 , 8 , 9 , 10 , 14 , 15 ]. In contrast, the presence of shorter starch chains would produce shorter or weaker single and double helices, resulting in inferior crystalline structures within the granules [ 2 , 8 , 9 , 10 , 14 , 15 ]. Therefore, the role of amylose content and amylopectin fine structure on starch physicochemical and functional characteristics and in vitro digestibility has been extensively studied [ 8 , 9 , 10 , 14 , 16 ].…”