论文总字数：19583字

摘 要

大蒜加工过程中，经常会出现绿变现象，不仅影响了产品的外观，而且使得S-烯丙基-L-半胱氨酸、阿霍烯等功能性成分含量降低。本文旨在探讨大蒜材料在萌发和浸泡过程中的理化性质。考察了大蒜萌发和浸泡中γ-谷氨酰转肽酶活力、蒜氨酸酶活力、绿变指数的变化，探讨大蒜绿变与酶的关系。得出结论如下：

1. 大蒜在4 ℃萌发条件下放置34 d时，γ-谷氨酰转肽酶活力从0.90 mU/g增加至1.60 mU/g。绿变指数D₅₉₀也相应从2.10增加至13.02。

(2) Ca² 具有激活大蒜中γ-谷氨酰转肽酶和蒜氨酸酶的活力、促进大蒜绿变的作用。采用10 mmol/L的CaCl₂溶液浸泡34 d的大蒜，γ-谷氨酰转肽酶活力、蒜氨酸酶活力和绿变指数D₅₉₀分别由浸泡前的1.60 mU/g、105.99 U/g、13.02增至2.11 mU/g、149.81 U/g、13.50。

本论文揭示了萌发和浸泡对大蒜绿变和酶活的调控作用，为提高大蒜加工产品质量和大蒜新产品开发提供了必要的理论和技术依据。

关键词：大蒜绿变；γ-谷氨酰转肽酶；蒜氨酸酶

Change in the Physical and Chemical Properties of Garlic during Sprouting and Soaking

ABSTRACT

Greening of garlic is a serious problem which frequently occurs in the garlic processing industry. Due to the greening, final products might have undesirable appearance and contain less functional compounds such as S-allyl-L-cysteine, ajoene, etc. The objectives of the present study were to reveal the regulation effect of germinate and soak on enzyme activity and greening of garlic, the changes of γ-glutamyltranspeptidase activity, allinase activity and garlic greening index were investigated. The relationship between the enzyme activity and garlic greening index was diecussed. The experimental results could be concluded as follows.

1. The γ-glutamyltranspeptidase activity increased from 0.90 mU/g to 1.60 mU/g, and correspondingly the garlic greening index increased from 2.10 to 13.02 during the storage of garilc bulbs for 34 d at 4 ℃.
2. The γ-glutamyltranspeptidase activity and allinase activity were increased, and the garlic greening was facilitated, by adding of Ca² to garlic bulbs. The γ-glutamyltranspeptidase activity, allinase activity and garlic greening index increased from 1.60 mU/g, 105.99 U/g, 13.02 to 2.11 mU/g, 149.81 U/g, 13.50 respectively, during the soaking of 4 ℃-34 d stored garlic bulbs in a 10 mM CaCl₂ solution.

The present study revealed the regulation effect of germinate and soak on enzyme activity and greening of garlic, and clarified the mechanism of garlic-greening inhibition by onion.The present study provided the theoretical basis and technical data for improving the quality of garlic products and developing new garlic processing products.

Key words: garlic greening，γ-glutamyltranspeptidase，alliinase

目 录

摘 要 I

ABSTRACT II

第一章 文献综述 1

1.1 前言 1

1.2 大蒜绿变反应过程 1

1.3 γ-谷氨酰转肽酶 3

1.3.1 催化反应类型 3

1.3.2 酶学性质 4

1.3.3 与大蒜绿变的关系 4

1.4 蒜氨酸酶 4

1.4.1 催化反应类型 4

1.4.2 酶学性质 5

1.4.3 与大蒜绿变的关系 5

1.5 研究目的与意义 5

第二章 实验材料及方法 6

2.1 材料 6

2.2 试剂 6

2.3 仪器与设备 6

2.4 方法 6

2.4.1 萌发 6

2.4.2 浸泡 6

2.4.3 芽瓣比测定 7

2.4.4 γ-谷氨酰转肽酶活性测定 7

2.4.5 蒜氨酸酶活性测定 8

2.4.6 绿变指数测定 10

第三章 实验结果与讨论 11

3.1 芽瓣比的变化 11

3.2 γ-谷氨酰转肽酶活性的变化 12

3.3 蒜氨酸酶活性的变化 12

3.4 大蒜绿变与酶活的关系 13

第四章 结论与展望 18

4.1 结论 18

4.2 展望 18

参考文献 19

致 谢 22

第一章 文献综述

1.1 前言

大蒜(Allium Sativum L.)为百合科葱属植物蒜的鳞茎，二年生植物。其营养价值很高，含有蛋白质、糖类、脂肪和维生素、钙、磷、铁、硒、锗等矿质元素^[1](表1-1，表1-2)，还含有多糖、凝集素和一些酶类(如蒜氨酸酶、过氧化物酶、γ-谷氨酰转肽酶等)^[2,3]。大蒜中主要的生物活性物质是大蒜所特有的含硫化合物，这些含硫化合物赋予了大蒜很高的药用价值，如抗癌防癌、降血压、降胆固醇、抗氧化、抗肿瘤、抗血小板聚集、降血脂和抗动脉粥样硬化、保护心血管、降低血糖等作用^[4,5]。大蒜的休眠期短，易发芽霉变和品质劣变，长期贮藏损耗率较高。大蒜除鲜食外，常加工成蒜片、蒜粉、黑大蒜、蒜泥等。但是大蒜制品在加工过程往往中会出现绿变的现象，这一定程度上影响了产品的外观质量，妨碍了大蒜进行二步加工。而大蒜绿变与其生理休眠状态有关，处于休眠的大蒜，其蒜泥不会发生变绿现象，结束休眠大蒜的蒜泥会变绿。因此，研究处于不同生理期的大蒜，对探究抑制大蒜绿变的途径、大蒜规模化加工生产具有重要意义。

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