Textural Properties, Resistant Starch, and in Vitro Starch Digestibility as Affected by Parboiling of Brown Glutinous Rice in a Retort Pouch

Abstract

The effects that two preparation methods (parboiling with different degrees of gelatinization and parboiling with enzymatic hydrolysis) have on the qualities of brown glutinous rice were investigated in order to optimize the pretreatment conditions of brown glutinous rice for the ready-to-eat product in retort pouch. The brown glutinous rice was parboiled at various temperatures (50, 70 and 90C) and steamed at atmospheric pressure until the gelatinize level of 60, 80 and 100%. For the parboiling with enzymatic hydrolysis, the brown glutinous rice was immersed in xylanase before steamed. Results showed that parboiling not only affected the nutritional composition, color, and texture of glutinous rice but also decreased the Glycemic index (GI) to 61.3 ± 0.03 and raised the Resistance starch (RS) to 2.9 ± 0.02. There was interaction among RS, GI, and the amylopectin content of brown glutinous rice during parboiling without enzymatic hydrolysis. Amylopectin is directly proportional to GI but inversely proportional to RS. Enzymatic hydrolysis improved both the texture and the physical and chemical properties. In addition, the GI value of enzyme treated samples decreased to 62.7 ± 0.24 and the RS increased to 2.9 ± 0.05. The highest overall preference score was attained by parboiled rice which was soaked in water at 90°C and then steamed until 100%gelatinization.

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

“…A similar research study found that total reducing sugar contents increased sharply in the 16‐month storage period and thereafter, increased steadily. The rate of reduction in sugar content out of total sugar content increased with extended storage duration (Wiruch et al, 2019 ). In another study, Devraj et al reported significant reductions of 26.4–64.7% and 37.1–52.1% in the content of disaccharides, that is, sucrose and polysaccharides, that is, raffinose, respectively.…”

“…A similar research study found that total reducing sugar contents increased sharply in the 16month storage period and thereafter, increased steadily. The rate of reduction in sugar content out of total sugar content increased with extended storage duration (Wiruch et al, 2019)…”

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

“…Starch containing higher amylose tended to have a greater amount of amylose-lipid complex. As a result, the molecular formations potentially prevent starch chains from starch digesting enzymes [ 10 , 17 , 47 ]. This could result in a higher resistance to enzyme hydrolysis of rice starch, and thus a higher RS content [ 10 , 47 ].…”

“…As a result, the molecular formations potentially prevent starch chains from starch digesting enzymes [ 10 , 17 , 47 ]. This could result in a higher resistance to enzyme hydrolysis of rice starch, and thus a higher RS content [ 10 , 47 ]. In addition, it was also shown that the ability to resist the enzymatic digestion of rice starch is attributed to its large granule size [ 10 ].…”

“…The longer branch chains of amylopectin molecules are prone to give higher ordered and more stable crystalline structures [ 2 , 8 , 13 ]. These molecular formations would promote the starch molecular size and the strengthening of intra- and inter-molecular hydrogen bonds between both starch chains, eventually leading to an increase in the resistance to enzymatic hydrolysis and an increase in RS content [ 10 , 17 , 47 ]. Here, the similar RS content of KDML105 and RD6 starches was observed despite their differences in amylose content and granular size ( Table 1 , Table 3 and Table 6 ).…”