土豆射频熟化效果及特性转变机制研究

With rapid increases in the potato planting explosive development of potato processing industry pushed by government, the traditional potato heating methods cannot meet the demand in high efficiency and quality from modern potato industries. It is extremely urgent to study high-efficiency, reliable and environment-friendly physical alternatives for potato heat treatment. Radio frequency (RF) treatment has been identified as one novel physical heating method, providing significant advantages and broad application prospects in heating of agricultural products . This project will use potato as the material to investigate its heating mechanism by RF energy and study the microstructure of potato before/after RF treatment; By studying the physic-chemical indexes, heating dynamics and dielectric properties of RF heated potato to clarify the quality of production, water removal and temperature distribution during RF treatment; By studying the properties and structure of potato starch (included crystalline, crystallinity, molecular weight, polymerization degree and gelatinization properties) to clarify the influence of RF heating on structure and characteristic of potato starch to explain the mechanism of radio heating potato. This project mainly combines unique research capacities in two interdisciplinary research directions of food chemistry and food engineering to develop novel and efficient RF treatment for potato-related industries, it will significantly improve the efficiency in potato processing and product quality, extend shelf life, provide reliable mechanisms and new heating technology for the potato industries, and lay a foundation to establish effective RF treatment technology in other agricultural products.

面对目前国家大力推动土豆种植和加工业的形势，蒸煮熟化土豆的方法已无法满足高效高质量的产品加工需求，研究快速可靠环保的土豆熟化技术迫在眉睫。射频技术作为一种新型物理加热方法，在农产品热处理中具有明显技术优势和广泛应用前景。本项目对土豆进行射频熟化处理，研究其熟化效果及淀粉特性转变机制。通过研究土豆射频熟化过程中的理化指标、热动力学及介电特性，探明熟化过程中土豆内部水分迁移情况、加热均匀性及选择性加热特性；通过研究射频熟化过程土豆淀粉结构改性机制以及糊化特性，阐明射频处理对土豆淀粉结构的影响，并从机理上明确射频处理改变淀粉特性的规律，为射频熟化技术处理土豆的可行性及高效性提供全面的理论依据和技术指导。本项目利用食品工程和食品化学两大学科交叉融合，建立新型高效的射频土豆熟化技术，为我国土豆产业提供一种新型加工技术的理论和技术支持，并为其他农产品射频热处理技术奠定基础。

马铃薯种类丰富，其中紫色马铃薯还含有大量的多酚、花青素和类黄酮等抗氧化物质。本项目以马铃薯为对象，利用射频技术对其进行熟化处理并探讨马铃薯在熟化过程中的理化性质，介电特性，主要活性物质的抗氧化活性，温度分布，穿透深度及热动力学等方面的变化及相关机理。同时研究马铃薯熟化过程中射频对淀粉的作用效果，阐述水分含量与处理时间对马铃薯淀粉的结构与理化性质的影响并初步探究其影响机制。结果表明射频在加热效率上比传统加热方法有很大优势，同时均匀性优于微波加热。射频熟化处理对马铃薯中的维生素C和类胡萝卜素有更好的保留。同时对颜色影响较小。射频对紫色马铃薯中的抗氧化活性物质保留较好，其中多酚损失了4.28％，花青素损失了3.71%，类黄酮损失了35.05%。在通过DPPH、ABTS、FRAP三种抗氧化能力试验后，经射频熟化后的紫色马铃薯仍能保持较高的抗氧化活性。射频处理后的马铃薯湿淀粉晶型发生改变，平均粒径 (d(4,3))和表面积平均粒径 (d(3,2))随含水量增加而降低且随处理时间的延长显著增加。淀粉的碘蓝值、碘结合力、持水性、峰值黏度、崩解值、透明度、溶解度、膨胀力、终止温度 (Tc)、热焓值和稠度系数随含水量的增加而增加，但最低黏度 (TV)、最终黏度、回生值、储能模量 、损耗模量和流动特征指数则随含水量上升而逐渐降低。试验结果表明利用射频对马铃薯做熟化处理切实可行。相对于其他熟化方式其加热效率高，均匀性好。淀粉理化指标受到射频处理后性质会发生一定改变。