【作者】 梁丽松；

【导师】 张柏林；

【作者基本信息】 北京林业大学 ， 生物化学与分子生物学， 2011， 博士

【摘要】 板栗(C. mollissima B1)糯性是人们最为关注的食用品质之一,但来自不同品种及产区板栗间的糯性质地存在较大差异,并缺乏客观的板栗糯性质地评价方法。本文选取3个不同品种群9个产区共24个主栽品种板栗为试材,比较了不同品种间糯性质地的差异；研究了板栗种仁组织形态结构、物质组成和理化性质与糯性的关系；通过观察不同糯性板栗淀粉形态特征,分析了淀粉特性与糯性质地的关系；应用主成份分析讨论了糯性质地各影响因素间的相关性,构建了板栗糯性评价方法,旨在通过板栗糯性质地构成物质建立板栗糯性质地评价体系,为板栗选种育种和深加工利用提供理论依据。主要研究结果如下1、板栗品种不同,种仁糯性水平不同,并具有一定的区域特性。板栗种仁糯性质地与品种密切相关,“北方品种群”板栗普遍有较高的糯性水平,来自安徽(“中间类型品种群”)和湖南(“南方品种群”)产：区的板栗糯性水平较低。2、板栗糯性水平与淀粉粒结构有关。板栗熟化后,种仁组织细胞内的淀粉粒膨胀糊化,呈蜂窝状结构,“高糯性”与“低糯性”板栗熟化后蜂窝状结构中的蜂窝孔致密程度不同,存在组织形态差异。其中“高糯性”板栗组织的蜂窝孔相对较少,组织粘连在一起;而“低糯性”板栗组织的蜂窝孔数量多,形成类似于立体网状结构。“低糯性”组织结构较为松散,“高糯性”板栗组织结构相对紧密。这种组织形态差异是不同品种板栗呈现不同糯性口感质地的。3、淀粉是板栗质地构成的最基本要素。淀粉膨胀势和糊化特征值与种仁糯性感官评分呈显著相关性表明,淀粉的膨胀特性和糊化特性与板栗糯性紧密相连。进一步研宄表明,淀粉膨胀势大小与淀粉结晶度显著负相关,与支链淀粉碘蓝值、淀粉碘结合力以及支链淀粉/直链淀粉含量比值显著正相关;其糊化特征值与支链淀粉碘蓝值、全淀粉碘蓝值以及支链/直链淀粉含量比值有显著相关性。表明淀粉中的直链淀粉与支链淀粉构成比例及其各自的分子结构特性(结晶度、支链淀粉分支链长和直链淀粉链长分布)使板栗具有了最本质的糯性质地特性。研究证实,“高糯性”板栗淀粉普遍具有较低的结晶度和支链淀粉碘蓝值、较高的全淀粉碘蓝值和支链/直链淀粉比例;“低糯性”板栗则相反。支链淀粉分支化程度越高、直链淀粉链长越短、结晶度越低,板栗的基本糯性越强。4、蛋白质和脂肪在很大程度上通过与淀粉形成复合物对淀粉的膨胀、糊化和回生特性产生影响,进而显著影响板栗种仁的糯性质地。(1)种仁中的蛋白质含量以及淀粉含量与蛋白质含量的比值均与板栗糯性显著相关,与淀粉结合的蛋白质种类和含量在不同糯性等级板栗之间存在明显差异；而淀粉结合脂中的脂肪酸组成与板栗糯性评分关系密切,其中C16：0脂肪酸、C18：2脂肪酸以及C16脂肪酸/C18脂肪峻/支链淀粉/直链淀粉的比值与种仁糯性的关系更为显著。(2)脱脂、脱蛋白处理后板栗粉和板栗淀粉的膨胀、糊化、回生特性都发生了显著变化,表现为膨胀势显著升高、“糊化温度”降低和糊化“峰值时间”提前,在很大程度上蛋白质和脂质的存在限制了淀粉的膨胀与糊化。这种变化与品种密切相关,并具有明显的地域分布特性。“北方品种群”板栗粉及板栗淀粉通常具有更高的膨胀势水平、较低的“糊化温度”和“峰值时间”,容易膨胀和糊化。进一步研究表明,脱脂、脱蛋白板栗粉和板栗淀粉膨胀势和糊化特征值的变化与蛋白质含量、淀粉结合脂含量、淀粉结合脂中C16/C18脂肪峻比例以及饱和/不饱和脂肪酸比例之间存在显著相关性。可见,板栗粉和板栗淀粉的膨胀、糊化、回生特性显著受到种仁物质组成及其性质的影响,是各物质组成对种仁糯性质地协同作用的综合反映。通过改变淀粉、蛋白质、脂肪的组成可以有目的地改善板栗种仁食用品质和加工性状。5、内在外在因素综合作用使板栗种仁具有不同的糯性质地特性。基于24个与种仁糯性相关因子的重要性排序,构建了板栗种仁糯性质地多元评价方法,该方法对24个品种板栗糯性检验表明,19个板栗品种的糯性与感官评价结果相吻合,正确率达79%以上。表明已建立的板栗糯性质地数字模型预测水平高,能够比较客观、真实地反映板栗种仁的糯性水平,有较好的实用价值。本文首次对板栗糯性质地的物质基础进行系统研究,初步揭示板栗糯性质地构成的物质,提出了板栗糯性质地等级划分依据,初步建立了以板栗内外在因素为基础的糯性质地多元评价方法,这些工作为板栗产业从品种选育到精深加工利用提供了理论支持。更多还原

【Abstract】 Waxy property is one of the most important edible quality of Chinese chestnut(Castanea mollissima Blume), and varies greatly according to its varieties and cultivated areas. To date no good method for evaluating the waxy property in chestnut has been set up as while. In this study,24 varieties of Chinese chestnut from 3 cultivar groups collected at 9 different cultivated areas were sampled to deal with the waxy texture. The objectives of this present study were:(1) to study the relationship between the morphological structure and composition substance of chestnut seeds and its waxy property; (2) to analyze the contribution of chestnut starch properties to waxy quality; (3) to use PCA (Principal Component Analysis) to discuss the correlation among factors that influencing waxy texture of chestnut; (4) to establish a PCA-based system that evaluated the waxy quality of chestnut. This study was the first to integrate the external and internal factors that affect the waxy property of chestnut together, and attempted to provide theoretical guide for the breeding and fine processing of chestnut. The following are main results.1. Waxy quality of chestnut depended greatly on its cultivar and cultivated areas. North Cultivar Group (NVG) in chestnut showed high waxy quality, whereas these varieties from Anhui and Hunan areas have poor waxy quality.2. The waxy level of chestnut was affected by its starch granule structure. The curing treatment resulted in chestnut starch granules to gelatinize and then form a cellular texture adhered together. The cellular structures differed between High Waxy Quality (HWQ) chestnut and Low Waxy Quality (LWQ) chestnut after curing due to honeycomb densification. Normally, the chestnuts with HWQ less honeycombed and starch granules adhered strongly. The chestnuts with LWQ produced more honeycomb with three-dimensional net structure. Differences in the structure of starch granules cured cause different varieties to have specific waxy texture.3. Starch properties contributed largely to the waxy texture of chestnut. The swelling power and pasting character of chestnut starch affected the waxy property based on sensory evaluation score. The swelling power of starch negatively correlated with its crystallinity, and positively correlated with Iodine Blue Value (IBV) of amylopectin. Iodine Combining Power (ICP) of Starch and amylopectin/amylase content ratio (AP/AM ratio). The pasting characteristic value of starch correlated with IBV of amylopectin, IBV of starch and AP/AM ratio. Basically, AP/AM ratio and crystallinity, branch chain length of amylopectin and chain length distribution of amylose were factors affecting the waxy quality of chestnut. Unlike the chestnut starch with LWQ, the chestnut starch with HWQ has lower crystallinity and IBV of amylopectin, higher IBV of starch and AP/AM ratio. Higher branching degree of amylopectin, shorter chain length of amylase and lower crystallinity higher waxy property chestnut has.4. Protein and fat were proved to be main substances affecting the waxy quality of chestnut throughout forming starch-protein or starch-fat complex that influenced the swelling and pasting properties of starch.(1) Waxy property significantly related to protein content and starch/protein content ratio stored in nuts. The types and contents of starch-associated-protein were obviously different due to waxy quality among varieties. There was close relationship between Sensory Evaluation Score (SES) of waxy quality and fatty acid (FA) composition, especially for starch-lipid of C16:0 FA, C18:2 FA and the ratio of C16/C18 and AP/AM.(2) The swelling and pasting properties of chestnut powder and nuts greatly changed after de-fate and de-protein treatments. De-fat and de-protein treatments caused chestnut starch to increase its swelling power.’Pasting temperature’decreased and ’Peak time’was shorter. The swelling and pasting of starch was dependant on the presence of protein and lipid. Moreover, the change in swelling and pasting was subjected to chestnut varieties and its cultivated areas. Chestnut powder and starch from NVG had higher swelling power, lower’Pasting temperature’and shorter’Peak time’, easily swelling and pasting. In additions, the changes in swelling power and pasting characteristic value was significantly subjected to protein content, starch-lipid content, C16/C18 FA ratio and SFA/UFA ratio in starch-lipid. Thus, the swelling and pasting properties comprehensively were influenced by composition and property of substance. Edible quality and processing character of chestnut might be improved on purpose throughout the adjust of its starch, protein and lipid.5.24 internal and external factors were recognized intergratedly to cause chestnut to have different waxy property among varieties. A PCA-based system was established for evaluating the waxy texture property of chestnut. The waxy quality of 19 chestnut’s varieties according to the PCA-based system coincided with that from sensory evaluation method, and the accuracy rate was more than 79%.6. In summary, this study was the first time to prove various internal and external factors to cause Chinese chestnut to have diversity in waxy quality. The diversity in waxy quality suggests that PCA-based system should be promising for the evaluation of chestnut waxy texture.更多还原