【作者】 韩忠；

【导师】 曾新安； 于淑娟；

【作者基本信息】 华南理工大学 ， 制糖工程， 2011， 博士

【摘要】 本文以玉米淀粉为研究对象，系统地研究了电场（脉冲电场和直流电场）对玉米淀粉物理化学性质、酶解特性及消化特性的影响，并对电场处理过程中的能量及作用机理进行了分析。主要研究工作如下：1）系统地研究了脉冲电场对不同链/支比的玉米淀粉物理化学性质的影响。玉米淀粉的粒径大小、分子量、相对结晶度、膨胀度和溶解度均随着直链淀粉含量的增加而减小，其顺序为Waxy＞Normal＞G50＞G80。经过脉冲电场处理之后，玉米淀粉颗粒表层被破坏，随着脉冲处理强度和时间的增加，玉米淀粉颗粒表面出现不同程度裂痕而变得粗糙，淀粉的平均粒径增大，分子量降低、相对结晶度、膨胀度和溶解度、玉米淀粉糊的G′、G″和η*均有所减小。同时，由TGA和NMR分析可知，脉冲电场对玉米淀粉的基本化学结构没有影响。2）系统地研究了直流电场对不同链/支比的玉米淀粉物理化学性质的影响。经过直流电场处理之后，尤其加热到65℃，淀粉颗粒的表层被破坏，支链淀粉断裂析出，与水作用加快，导致其迅速膨胀而粒径增大和结晶区的破坏；玉米淀粉的膨胀度和溶解度均有所减少，进而导致玉米淀粉糊的粘弹性（G′、G″和η*）下降。同时，由TGA和NMR分析可知，直流电场对玉米淀粉的基本化学结构没有影响。3）脉冲电场和直流电场处理均能提高普通玉米淀粉的酶解率。对于玉米淀粉的消化性，经过高强脉冲电场处理之后，随着脉冲处理强度和时间的增加，玉米淀粉的RDS和RS值均有所增加，而SDS值均有所降低。经过直流电场处理后，玉米淀粉的RDS值有所增加，SDS值有所减小。4）脉冲电场处理淀粉乳的过程，其能量随着脉冲处理强度和时间的增加而增大，最高达238.50J·g-1。直流电场处理淀粉乳的过程，其能量随着溶液的温度升高而增大，最高达286.23J·g-1。脉冲电场处理玉米淀粉的作用机制为空间电荷极化理论，而直流电场处理玉米淀粉的作用机制为电流加热膨胀理论。更多还原

【Abstract】 The effects and mechanism of electric fields (pulsed electric fields and ohmic heating) onthe physicochemical properties and digestibility of corn starch were studied in this paper.Meanwhile, the energy analysis of electric fields treatments was also done. The mainconclusions obtained were introduced as follows.1） The effects of pulsed electric fields (PEF) on the physicochemical properties of cornstarch were systematically studied. The granule size, molecular weight, relative crystallinity,swelling power and solubility of corn starch were decreased as the increasingamylose/amylopectin ratios(Waxy＞Normal＞G50＞G80). After being treated by PEF, somecoarseness or damage had been generated on the surface of the corn starch granules and thegranule size was increased. Meanwhile, molecular weight, relative crystallinity, swellingpower and solubility of corn starch and the values (G′, G″and η*) of corn starch pastes wereall decreased as the increasing electric fields strength and treatment time. However, the PEFtreatments did not change the chemical structure of corn starch by TGA and NMR analysis.2）The effects of ohmic heating (OH) on the physicochemical properties of corn starcheswere also systematically studied. After OH treatments, especially being heating to65℃, thesurface of corn starch granules was broken and starch granules could tarch granule couldmore effectively absorb water and swell, which led to an increase of granule size and thedamage of crystalline region. Meanwhile, swelling power and solubility of corn starches weredecreased, resulting in the decrease of the values (G′, G″and η*) of corn starch pastes. Andfrom TGA and NMR analysis, the chemical structure of corn starch was not affected by OHtreatments.3）The PEF and OH treatments can both increase the enzymic hydrolysis rate of cornstarches. For digestibility, after PEF treatments, RDS and RS were increased while SDS wasdecreased as the electric fields strength and treatment time were increased; after the OHtreatment, RDS was increased whereas SDS was decreased.4）The input energy of PEF treatmen was increased up to238.50J·g-1to affect thebehaviour of corn starch, and for the OH treatments, the highest value was286.23J·g-1. The mechanism of PEF treatments on corn starch was space charge polarization, and themechanism of OH treatments on corn starch was heated-swelling.更多还原