原料冷冻处理对干红葡萄酒质量的影响

原料冷冻处理对干红葡萄酒质量的影响

STUDY ON THE EFFECT TO THE QUALITY OF DRY REDWINE BY FREEZING TREATMENT

作者：张红娜　　导师：高　畅

西北农林科技大学　　发酵工程2011届硕士

摘　要

本文以酿酒葡萄媚丽为试材，以传统干红葡萄酒酿造工艺为对照，研究了不同冷冻处理葡萄原料对葡萄酒质量的影响。冷冻处理条件包括四个因素，每个因素取两个水平：冷冻温度选取－10℃和－35℃，冷冻时间选取4h和6h处理，原料状态包括葡萄果皮和葡萄果粒两种，解冻方式取自然解冻和微波快速解冻两种。

冷冻可以破坏植物细胞的结构并导致细胞膜通透性改变。基于这一原理，本文在发酵前对葡萄原料进行不同的冷冻处理以破坏细胞结构，促进葡萄酒浸渍发酵过程中对果皮细胞中化学物质的浸提，从而提高葡萄酒质量。酒精发酵条件与干红葡萄酒传统浸渍发酵工艺相同。

本文通过理化指标和感官分析评价葡萄酒的质量。主要结果如下：

1.　对葡萄酒理化指标进行分析可得，冷冻温度对葡萄原料的破坏起决定作用，－35℃冷冻葡萄原料，即使冷冻时间短，细胞破坏作用也较好，葡萄酒中总酚含量和色度值较高，明显高于－10℃处理的葡萄酒中总酚含量和色度值。原料冷冻6h酿造的葡萄酒总酚、单宁含量和色度值低于4h处理的值，在6h内冷冻时间长短与葡萄酒中物质含量高低不成正比。解冻方式对细胞破坏作用的影响较小。葡萄果粒冷冻与葡萄果皮冷冻相比，葡萄酒中总酚含量和色度值高，葡萄果粒冷冻略有优势。原料冷冻处理与对照相比，葡萄酒总酚含量和色度值较低。

2.　本研究采用HPLC法测定葡萄酒中单体酚和花色苷含量，进一步研究冷冻处理对葡萄酒品质的影响。

采用冷冻处理的原料酿造的葡萄酒，14种单体酚物质均被检测出，而对照葡萄酒样只能检测到13种，不含有咖啡酸。冷冻组葡萄酒，单体酚总量均高于对照组，因而葡萄原料冷冻处理可以提高葡萄酒酚类物质含量。类黄酮类与非类黄酮类单体酚物质在葡萄酒中的比例主要与冷冻时间有关。

试验葡萄酒特征花色苷为3'-甲花翠素-3-O-葡萄糖苷和花青素-3-O-葡萄糖苷，这两种花色苷占葡萄酒中花色苷总量的90%以上。原料冷冻处理的葡萄酒中3'-甲花翠素-3-O-葡萄糖苷和花青素-3-O-葡萄糖苷含量高于对照组，葡萄酒的色度值较高。因而，葡萄原料冷冻处理对葡萄果皮细胞有一定的破坏作用，可以促进果皮细胞中的花色苷类物质在浸渍发酵过程中浸入葡萄酒中。不同冷冻处理条件花色苷在葡萄酒中含量略有差异，与对照相比，都提高了葡萄酒花色苷总量。

3.　对葡萄酒进行感官分析，结果表明，试验葡萄酒在外观上差异显著，葡萄原料经－35℃冷冻4h、自然解冻处理和－10℃冷冻6h自然解冻的葡萄酒外观质量较好，高于对照葡萄酒样，可见，冷冻处理葡萄原料能提高葡萄酒外观质量。试验葡萄酒的香气和口感质量差异不大，果皮－35℃冷冻4h和果粒－10℃冷冻6h处理且自然解冻的葡萄酒比对照葡萄酒的香气和口感质量好。其他处理效果不及对照酒。

4.　冷冻葡萄原料酿造的葡萄酒质量有一定程度的提高，相同条件处理葡萄果粒的冷冻效果比葡萄果皮略好，但是冷冻葡萄果粒消耗的能量为果皮的12.5倍，能耗高且处理量大，将导致葡萄酒成本增高。因而，葡萄果皮－35℃冷冻4h为最佳处理条件，有利于葡萄酒质量的提高和节约能源，在实际生产中可考虑应用。

关键词　葡萄酒　冷冻处理　多酚　花色苷　感官分析

Abstract

Dry red wine was made by wine-grape Meili strain with different frozen treatments and the effect of the treatments on wine quality was studied,with the traditional brewing for check. The treatments are: frozen temperature,-10 ℃ and -35 ℃;freezing time,4 h and 6 h;the raw material status,grape fruit peel and grape fruit granule;unfreeze mode,natural and microwave .

Freezing can damage the structure of plant cell and change the cell membrane transparence. So,grape was frozen before fermentation to destroying the cell structure and accelerating the immersion of chemicals in skins during the fermentation,with the purpose of improving wine quality. The alcoholic fermentation was same with the traditional way of dry red wine.

Wine quality was evaluated by physical and chemical indicators and sensory analysis. The main results are as follows:

1.　Through the physical and chemical analysis,the content of total phenols and color density in wine by －35℃ treatment are higher than －10℃,even with shorter freezing time. It indicates the freezing temperature is mainly in destroying the material. The content of total phenols and tannin and color density with 6h are lower than that with 4h. The effect of unfreeze code on cell damage is minor. Grape fruit is better compared with the skin. Comparing the freezing treatment and the traditional,the total phenols and color density are lower.

2.　The content of mono phenol and anthocyanin was determined by HPLC.

14m　ono phenols in wine were detected in the test wines with 13 in the comparisons,without caffeic acid. The content of mono phenols was higher in the test wines. The ratio of flavonoid and non-flavonoid was different,mainly related to the freezing time.

The typical anthocyanin in the test wines were Pt-3-O-Glu and Cy-3-O-Glu,above 90% of the total anthocyanin in wine. The test wine has higher color density,Pt-3-O-Glu and Cy-3-O-Glu,indicating freezing can damage the grape skin and accelerate the transaction of anthocyanin from skin to must. The content of anthocyanin was different by different freezing treatments;however,the total content was increased,compared with the comparisons,indicating freezing treatment can improve the wine quality.

3.　The sensory analysis showed two test wines with grape frozen for 4h at －35 ℃ and frozen for 6h at －10 ℃,both unfrozen naturally got better appearance quality than the comparison,indicating freezing treatment on material can improve the wine appearance quality. The flavor and taste of test wine had little difference. Grape skin frozen for 4h at －35 ℃ and grape fruit frozen for 6h at －10 ℃,both unfrozen naturally had better flavor and taste than the comparison.

4.　Wine quality was improved to some extent made by frozen grape. The effect of frozen treatment to the berry skin was better than grape at the same conditions,but the energy consumption of frozen grape was 12.5 times of grape skin,and it would lead to higher costs of wine for the large capacity. Thus,it was the best frozen treatment condition that the grape skin freezing at －35 ℃ for 4h,and it was beneficial to improve the quality of wine and save energy,and could be used in production.

Key words　Wine　Frozen treatment　Polyphenolic compounds　Anthocyanin　Sensory analysis