Presence and Activity of Various Amylases in Rice: Effect on Texture and Leached Sugar Composition during Cooking

Abstract

Amylase isozymes from non-glutinous japonica and indica rice types showed various band patterns, strengths and intensities based on zymography. Major bands were presumed to be α-and β-amylase according to their molecular weights; other amylases, 270 and 200 kDa in size, were also detected. Three debranching enzymes (DBEs) were detected from the dye pattern as well. Amylase activities were observed at pH 7.0 during rice cooking. However, the α-amylase activity at pH 7.0 was 50% lower than that at pH 5.0; DBE, β-amylase, and α-glucosidase values were similarly reduced by 25%, 90% and 99%, respectively. α-Amylase activity and DBE activities correlated positively with both the amount of maltooligomer leached during rice cooking and the adhesiveness of cooked rice. Thus, it is considered that the activity of amylase isozymes affects the palatability of cooked rice. Therefore, enzymes from rice endosperm may represent a new and highly useful biomarker for evaluating the palatability of cooked rice.

Effect of Endogenous Hydrolytic Enzymes on Glucose Liberation and Ecotypical Difference in Hot-water-treated Rice Grains (Oryza sativa L.)

“…Because there was no significant difference in the activity of α-glucosidase between groups, the difference in glucose accumulation is thought to be due to hydrolytic enzymes other than α-glucosidase, namely α-amylase, β-amylase and debranching enzyme. Tsujii et al (2013) reported a relationship between endosperm amylase and the amount of sugars (reducing sugars and total sugars) leached during rice cooking. They found that α-amylase activity and debranching enzyme activity was positively correlated with the amount of sugar leached during rice cooking.…”

“…Most interestingly, Tsujii et al (2013) revealed that the activity of amylase isozymes affects the palatability of cooked rice and suggested that the enzymes in rice endosperm are potential useful markers of palatability.…”

“…Recently, Nakamura et al (2012) reported that a physical property (adhesion) was correlated with enzyme activities (cellulase and xylanase) and they found discriminative DNA bands by PCR amplification of these enzymes. Tsujii et al (2007) also reported the amylase activity of glutinous rice grains was correlated with the paste viscosity.Most interestingly, Tsujii et al (2013) revealed that the activity of amylase isozymes affects the palatability of cooked rice and suggested that the enzymes in rice endosperm are potential useful markers of palatability.In this study, we aimed to clarify varietal and ecotypical differences in glucose accumulation caused by the activity of endogenous hydrolytic enzymes. inorganic fertilizer applied at a standard rate of 80 kg N, 35 kg P, and 66 kg K per ha.…”

The Rice Grain Localization of Endosperm Enzyme Activity

“…There are various enzymes in the endosperm of rice grains. In previous studies, we showed that rice endosperm enzyme activity affects the taste and texture of cooked rice (Tsujii et al, 2007a(Tsujii et al, , 2007b(Tsujii et al, , 2009(Tsujii et al, , 2010(Tsujii et al, , 2012(Tsujii et al, , 2013. Tran et al have reported the relationship between cooked rice taste and α-and β-amylase activities (Tran et al, 2001(Tran et al, , 2005.…”

“…have shown that some enzymes are involved in eating quality (Tsujii et al, 2013). The activities of the evaluated enzymes are shown in Table 3.…”