饲料限水糊化动力学及其颗粒结构特性的表征

饲料的糊化作为一种功能特性广泛存在于饲料的热加工中，水分、温度和时间是影响饲料糊化的重要工艺参数。为探究饲料在水热处理过程中的糊化动力学参数及饲料颗粒结构的内在变化，该研究基于均匀板加热法，将25%和30%水分的育肥猪配合饲料，分别在75、80、85、90和95 ℃温度下，进行0.5、1、3、5、7和10 min加热时间的热处理，分析热处理后饲料样品的糊化程度、糊化动力学参数、结晶特性、双折射特性和微观形貌等理化性质。结果显示，水分是饲料糊化的第一限制性因素，25%和30%水分饲料的最大糊化度分别为0.320 6±0.016 2和0.668 8±0.015 0，饲料的糊化过程遵循非线性一级动力学模型，且在热处理时长达到3 min左右时，糊化度趋向糊化终端的渐进值；由Arrhenius公式回归得到的25%和30%水分饲料糊化活化能分别为11 356.58和52 705.59 J/mol，是限制水分条件下的

Characterization of gelatinization kinetics and particle structure of feed under limited moisture condition

Abstract: The gelatinization of starch in feedstuffs as a functional property is applied extensively in feed thermal processing, and the moisture, temperature and time are the important technological parameters affecting the gelatinization of feed. In order to explore the gelatinization kinetic parameters and intraparticle structural changes in formula feed during the process of hydrothermal treatment, the heat treatment of formula feed for finishing pigs (moisture-adjusted to 25% and 30%) was carried out at different temperature, i.e. 75, 80, 85, 90 and 95 ℃, for different heating time, i.e. 0.5, 1, 3, 5, 7 and 10 min, respectively, based on the homogeneous plate heating method. The degree of feed gelatinization was quantified by enzymatic method, and polarized light microscopy, X-ray diffractometry, scanning electron microscope were used to characterize the physical and chemical properties of samples after heat treatment, such as, gelatinization kinetic parameters, crystallization characteristics, birefringence and micro morphology. The results showed that full gelatinization did not occur even at high enough temperature under limited moisture condition. The maximum gelatinization degree of feed with 25% and 30% moisture were 0.320 6±0.0162 and 0.668 8±0.015 0, respectively. The gelatinization process of feed followed nonlinear first order kinetics model. The gelatinization degree tended to the asymptotic value of terminal extent of gelatinization, when the heat time reached about 3 min. Compared with the gelatinization activation energy of natural starch in the previous study, the gelatinization activation energy of feed with 25% and 30% moisture in this research, 11 356.58 and 52 705.59 J/mol, obtained from regression of Arrhenius formula was relatively low, and it could only be regarded as