Barley starch behavior in the presence of rutin under subcritical water conditions

Characterization of temperature-dependent subcritical water hydrolysis pattern of strong and floury rice cultivars and potential utilizations of their hydrolysates

This study investigated the effects of subcritical water (SW) temperatures on the hydrolysis pattern and characteristics of hydrolysates prepared with strong rice (SR) and floury rice (FR). The characteristics of the hydrolysates were generally dependent on the rice cultivar in the SW temperature range of 150-250 °C, while the cultivar dependence was diminished at temperatures greater than 300 °C. Based on brix and reducing sugar content, an optimal production of rice hydrolysates was obtained at a SW temperature range of 200-250 °C. However, thermal conversion of sugar into acids, 5-hydroxymethylfurfural (HMF) and furfural was manifested at 250 °C. The rice hydrolysates prepared at 250 ∼ 300 °C had the highest antioxidant activity with strong umami intensity, but they suppressed the growth of prebiotics. Therefore, the present study demonstrated that controlling the SW temperature is crucial to improve rice hydrolysis efficiency and to regulate the physiological activity of the hydrolysates.

Starch-guest complexes interactions: Molecular mechanisms, effects on starch and functionality

Starch is a natural, abundant, renewable and biodegradable plant-based polymer that exhibits a variety of functional properties, including the ability to thicken or gel solutions, form films and coatings, and act as encapsulation and delivery vehicles. In this review, we first describe the structure of starch molecules and discuss the mechanisms of their interactions with guest molecules. Then, the effects of starch-guest complexes on gelatinization, retrogradation, rheology and digestion of starch are discussed. Finally, the potential applications of starch-guest complexes in the food industry are highlighted. Starch-guest complexes are formed due to physical forces, especially hydrophobic interactions between non-polar guest molecules and the hydrophobic interiors of amylose helices, as well as hydrogen bonds between some guest molecules and starch. Gelatinization, retrogradation, rheology and digestion of starch-based materials are influenced by complex formation, which has important implications for the utilization of starch as a functional and nutritional ingredient in food products. Controlling these interactions can be used to create novel starch-based food materials with specific functions, such as texture modifiers, delivery systems, edible coatings and films, fat substitutes and blood glucose modulators.

Further slowing down of hydrolysis of amylose heated with black soybean extract by treating with nitrite under gastric conditions

Black soybean (BSB), which contains cyanidin-3-O-glucoside (C3G) and procyanidins, is cooked with rice in Japan. The color of the cooked rice is purplish red due to the binding of C3G and reddish oxidation products of procyanidins. These components can slowdown pancreatin-induced hydrolysis of amylose more significantly than the hydrolysis of amylopectin, and can react with nitrous acid in the stomach. This manuscript deals with the effects of nitrous acid on pancreatin-induced hydrolysis of amylose heated with BSB extract. The hydrolysis of amylose heated with BSB extract was slow, and the slowdown was due to the binding of C3G/its degradation products and degradation products of procyanidins. The amylose hydrolysis was slowed down further by treating with nitrite under gastric conditions. The further slowdown was discussed to be due to the binding of the products, which were formed by the reaction of procyanidins with nitrous acid, to amylose. In the products, dinitroprocyanidins were included. In this way, the digestibility of amylose heated with BSB extract can be slowed down further by reacting with nitrous acid in the stomach.

Pancreatin-induced liberation of starch/cyanidin 3-O-glucoside complexes from rice cooked with black soybean that exhibit slow hydrolysis

Cyanidin 3-O-glucoside (C3G), which has various health-promoting functions, is contained in black soybean (BSB). In Japan and Korea, BSB is cooked with rice and the cooked rice appears purplish in colour. In this study, BSB was cooked with glutinous rice, non-glutinous rice, and high-amylose rice. The amount of C3G detected in high-amylose rice was greater than that detected in glutinous rice, suggesting that C3G combined more efficiently with amylose than with amylopectin. Pancreatin induced the liberation of starch/C3G complexes from the purplish cooked rice, and rate of the liberation was in the following order; glutinous rice < non-glutinous rice < high-amylose rice. The amylose/C3G complexes liberated from high-amylose rice was hydrolysed slowly, while the amylopectin/C3G complexes liberated from glutinous rice were hydrolysed into smaller amylopectin/C3G complexes that were difficult to further hydrolysis. Thus, C3G may be useful for preparing foods whose starch hydrolysis is slow.

The Procyanidin C1-Dependent Inhibition of the Hydrolysis of Potato Starch and Corn Starch Induced by Pancreatin

Procyanidins are contained in various foods, and their effects on starch hydrolysis have been reported. In Japan, black soybeans, which contain a trimeric procyanidin, procyanidin C1 (proC1), are cooked with rice and used to prepare dumplings. In this study, the effects of proC1 on the pancreatin-induced formation of reducing sugars and starch hydrolysis were studied using potato starch and corn starch. ProC1 inhibited both reactions; the inhibition was greater in potato starch than corn starch when added to heated potato starch and corn starch. When heated with proC1, its inhibitory effects decreased, especially in potato starch, suggesting the important role of proC1 itself for the inhibition of potato starch hydrolysis. ProC1 also inhibited the hydrolysis when added to heated, longer amylose (average molecular weight: 31,200), and the inhibition decreased when heated with the amylose. On the other hand, proC1 could not inhibit the hydrolysis when added to heated, shorter amylose (average molecular weight: 4500), but could when heated with the amylose, suggesting the important role of the degradation products of proC1 for the inhibition. We discuss the mechanism of the proC1-dependent inhibition of amylose hydrolysis, taking the molecular weight into account.

Ultrasound-assisted modification of rutin to nanocrystals and its application in barley starch pyrodextrinization

Ultrasound technology offers low cost and efficiency in nanodrug production and therefore was selected to investigate the formation of rutin nanocrystals, and its incorporation in barley starch pyrodextrin. Ultrasonication of rutin (600 W in water, citric acid and NaCl media) was carried out prior to rutin-barley starch pyrodextrinization (90 °C, 1 h). The ultrasound treated rutin (UTR) nanocrystal strands had <820 nm in diameter but shorter lengths from treatments at 27 and 36 kJ/cm³ (47 °C) compared to 3.9 and 7.0 kJ/cm³ (86 °C). All UTR showed color changes from yellow (control) to green and greenish-yellow. Also, thermal analysis indicated that UTR-citric acid had two polymorphs identified by melting peaks at 129.97 °C and 145.04 °C and an earlier decomposition at 179.47 °C compared to 244 °C (control). Rutin/UTR had no significant influence on the production of maltooligosaccharides (18-75 mg/mL of dextrin syrup). Ultrasonication enhanced rutin properties for oral delivery.