干热处理对完整芸豆细胞中内含淀粉结晶结构及其吸油性的影响研究

Effects of Dry Heat Treatment on Starch Crystalline Structure and Oil-binding Ability in Whole Pinto Bean Cells

本研究将分离完整的芸豆细胞作为芸豆全粉的研究模型,采用80~160℃不同干热温度对其处理后,探究温度对其内含淀粉结晶结构及细胞吸油性的影响。结果表明,干热处理后芸豆细胞仍保持完整形态,表面发生皱缩。在较低干热温度下(80~120℃),随着温度的升高,芸豆细胞内含淀粉的相对结晶度略有下降(约3%)。热力学性质测试观察到两个吸热峰,第一个为芸豆淀粉糊化峰,第二个为芸豆蛋白变性峰,两个峰的焓值都随温度升高而减小。在较高干热温度下(140~160℃),芸豆细胞内含淀粉的相对结晶度与较低干热温度处理的相比基本不变,蛋白变性峰消失。本研究发现随着干热温度的升高,芸豆细胞吸油性逐渐增强,芸豆细胞的三相接触角逐渐增加(122.0°~145.4°),但游离油酸体积逐渐下降(0.60~0.05 mL)。较高干热温度下(140~160℃)吸油稳定性较差。研究结果为芸豆全粉在食品配方中吸油性等应用提供了理论依据。

In this study, intact pinto bean cells were isolated as a research model of whole pinto bean flour, and subjected to dry-heat treatments. The effects of dry-heat temperature (80~160 ℃) on the crystalline structure and oil-binding ability of the starch were investigated. The results showed that pinto bean cells still remained intact with surface becoming wrinkled after the dry heat treatment. At lower dry heat temperatures (80~120 ℃), the relative crystallinity of the starch in the cells decreased slightly (ca. 3%) with increasing temperature. The thermodynamic analysis revealed the occurrence of two endothermic peaks: The first peak belonged to starch gelatinization, and the second one was the denaturation peak of pinto bean protein. The enthalpy values for both peaks decreased with increasing dry heat temperature. At higher dry heat temperatures (140~160 ℃), no change in the relative crystallinity of the starch in the cells was observed along with the disappearance of the protein denaturation peak, as compared with the cells treated at lower temperatures (80~120 ℃). It was found that as the dry-heat temperature rose, the oil-binding ability of the starch and the three-phase contact angle of pinto bean cells (122.0°~145.4°) increased gradually, but the volume of free oleic acid decreased (0.60~0.05 mL). The oil-binding stability was poor at higher dry heat temperatures (140~160 ℃). The results obtained in this research provided a theoretical basis for the utilization of the oil-binding properties of whole pinto bean flour in food formulations.