不同酵母多糖及酵母种类对荔枝酒品质的影响

通过添加不同酵母多糖发酵荔枝酒以及采用不同酵母菌种发酵酿制荔枝酒,分别研究酵母多糖种类、添加量、添加时间以及酵母种类对荔枝酒理化指标、感官品质的影响及防褐变效果。结果显示,在荔枝汁中添加250 mg/L Optired酵母多糖,发酵所得成品酒酒精度为12.8%vol,总酸、挥发酸等理化指标均符合国标,可显著提高荔枝酒感官品质,同时对荔枝汁中酚类物质有良好的保护作用,成品酒总酚含量提高35.9%,明显延缓其褐变进程,加速褐变后其褐变率下降156.2%。采用富产多糖的酵母发酵,其酿制的荔枝酒果香酒香浓郁协调,口感醇厚,圆润丰满,在贮藏过程中能有效保持香气、色泽、新鲜度等感官质量的稳定性,其中酵母BM4×4最为适宜。     

葡萄酒发酵过程中白藜芦醇含量变化的研究

跟踪2005年河北沙城、昌黎、天津蓟县和宁夏御马葡萄产区的干红葡萄酒生产过程,分别采集以赤霞珠葡萄为原料的不同发酵时期的样品,用高效液相色谱检测白藜芦醇含量,研究葡萄酒发酵过程中白藜芦醇含量的变化规律。结果表明,尽管不同产地在发酵过程中生成的白藜芦醇含量有所不同,但都随着果胶酶添加和酵母发酵的进行,白藜芦总醇含量逐渐上升,至主发酵时白藜芦总醇含量达到最高,进入苹果酸-乳酸发酵后,白藜芦醇含量有所下降并维持一定的水平。     

Anthocyanin fingerprint of clones of Tempranillo grapes and wines made with them

Background and Aims:  Different clones with distinctive enological characteristics have been identified in many grape cultivars, but data on differences in anthocyanin composition of clones of the same cultivar are scarce. Thus, it has been considered of interest to check changes in the anthocyanin fingerprint of six different clones of Tempranillo grapes grown in the same vineyard, and of wines made with them, over three consecutive years.
Methods and Results:  Data were submitted to different statistical procedures. Despite slight differences in the anthocyanin fingerprint of some clones (relative content of different anthocyanins analysed), variations from year to year were more important than differences in the anthocyanin profile of the clones considered. This fact was also observed when the content (mg/kg grapes) of those molecules was considered. Moreover, Tempranillo wines made with different clones could be classified by discriminant analysis, using the anthocyanin fingerprint or the levels (mg/L wine) of several anthocyanins as predictor variables, and the year grapes were collected as a classification factor.
Conclusions:  The anthocyanin fingerprint of six clones of Tempranillo grapes grown in the same vineyard and that of wines made with them over three consecutive years was affected mostly by weather conditions, despite slight differences in the anthocyanin fingerprint of some clones.
Significance of the Study:  This is the first report on the anthocyanin composition of different clones of Tempranillo grapes and of wines made with them, and indicates that anthocyanin fingerprint of Tempranillo wines depends mainly on agroclimatic factors, and not on genetic differences among clones.     

Enhancement of urea uptake in Chinese rice wine yeast strain N85 by the constitutive expression of DUR3 for ethyl carbamate elimination

Most of the fermented alcoholic beverages, particularly Chinese rice wine, contain the potentially human carcinogenic compound ethyl carbamate (EC). As a major EC precursor in Chinese rice wine, urea in fermentations can be transported into the yeast cell by urea permease and finally metabolized by urea carboxylase and allophanate hydrolase in vivo. To eliminate EC in Chinese rice wines, the present study constructed high urea uptake yeast strains N1‐D, N2‐D and N‐D, by introducing a strong promoter (PGK1p) into the urea permease gene (DUR3) of the industrial Chinese rice wine yeast N85, and by the restoration of the URA3 gene at the same time. With these self‐cloned, high urea uptake strains, the urea and EC in the terminal Chinese rice wine samples were reduced to different extents. With two copies of overexpressed DUR3, the N‐D strain could reduce the urea and the EC by 53.4 and 26.1%, respectively. No difference in fermentation characteristics was found between the engineered strains and the parental industrial yeast strain N85. These results could help to optimize the genetic manipulation strategy for EC elimination in Chinese rice wine production. Copyright © 2015 The Institute of Brewing & Distilling     

Melatonin in Mediterranean diet,a new perspective

The health‐promoting properties of the Mediterranean diet have been attributed, at least in part, to the chemical diversity of plant foods. Among phytochemicals, polyphenols represent the paradigm of the relationship between healthy foods and reduced risk of chronic‐degenerative diseases, although, in the past few years, a new element has enriched this scenario. Melatonin, and possibly other indoleamines recently discovered in some relevant Mediterranean foods, may represent a new factor contributing to the elucidation of the protective effects of diets rich in plant products. Therefore, in synergy with polyphenols and other bioactive phytochemicals (e.g. carotenoids and glucosinolates), melatonin may contribute to maximizing the benefits of healthy dietary styles. This brief survey deals with the occurrence of melatonin in the Mediterranean diet, with an emphasis on grape products, and focuses on the biological significance of dietary melatonin, an emerging and exciting topic in the field of nutritional sciences. © 2014 Society of Chemical Industry     

Profiles of Phenolic Acids and Flavan‐3‐ols for Select Chinese Red Wines: A Comparison and Differentiation According to Geographic Origin and Grape Variety

The profiles of phenolic acids and flavan‐3‐ols for the selected Chinese red wines and the potential of using phenolic acids and flavan‐3‐ols to differentiate the geographic origin and grape variety of wines from China are investigated in this study. Significant differences and markers could be found according to the geographical origin and grape variety. Through a canonical discriminant analysis a good differentiation was developed according to the geographic origin or grape variety, and the accuracy of the discriminant model was 88.9% and 100%, respectively. According to the phenolic acid and flavan‐3‐ols profiles of the wine samples and good differentiation in the region and the variety discriminant analysis, minimal fraudulent claims were noted for the Chinese red wines investigated.     

3 种酵母发酵生产红树莓酒香气成分的GC-MS分析

以D254、71B、D15 3 种果酒酵母进行发酵制备红树莓酒,并分析其香气化学成分。采用顶空-固相微萃取法提取3 种酵母酿造的红树莓酒香气成分;利用气相色谱-质谱进行香气成分的分离测定,结合计算机检索技术对分离化合物进行鉴定,利用峰面积归一法测定各香气化学成分的相对含量,共鉴定出105 种香气成分,其中D254、71B、D15酵母发酵的红树莓酒中分别检测出35、48、57 种香气成分,共有8 种成分相同。D254酵母发酵的红树莓酒的主要香气成分为3-甲基-1-丁醇（54.39%）;71B酵母发酵的红树莓酒的主要香气成分为丙烯酸异辛酯（12.41%）、脱羰秋水仙碱（12.06%）、癸酸乙酯（8.21%）;D15酵母发酵的红树莓酒的主要香气成分为三辛酸甘油酯（11.06%）和安非拉酮（8.81%）。综合气相色谱-质谱分析与感官评价结果表明,71B酵母发酵生产的红树莓酒香气较好,适宜大众口味,从而得出71B酵母为生产红树莓酒的最优菌株。     

Effects of branched‐chain amino acid addition on chemical constituents in lychee wine fermented with Saccharomyces cerevisiae

This study investigated the impact of single branched‐chain amino acid addition (L‐valine, L‐leucine, L‐isoleucine) on nonvolatile and volatile constituents in lychee wine fermented with Saccharomyces cerevisiae MERIT.ferm. The individual addition of branched‐chain amino acids decreased the consumption of proline with significantly different rates. The lychee wine with added L‐leucine and L‐isoleucine had higher odour activity values (OAVs) of isoamyl alcohol, active amyl alcohol and isoamyl acetate. The lychee wine with added L‐valine had higher OAVs of isobutyric acid and isobutyl alcohol (5.55 and 2.98, respectively), which were lower in the wine with added L‐leucine (2.91 and 1.02, respectively) or L‐isoleucine (3.43 and 1.73, respectively) relative to the control wine (4.18 and 1.77, respectively), suggesting interactive effects among the amino acids. These findings demonstrated that lychee wine aroma can potentially be manipulated via the addition of selected branched‐chain amino acids.     

桑葚果酒全渣发酵过程中生物活性物质及其抗氧化活性变化的研究

以桑葚干果为实验原料,考察桑葚发酵液中总酚、类黄酮、花青素的含量及抗氧化活性能力在发酵过程中的变化情况。结果表明:发现前发酵10 d的类黄酮和花青素类物质受发酵的影响逐渐变少,而总酚类物质含量逐渐升高;抗氧化活性总体上呈先升后降的趋势,相比于发酵开始时下降了近50%。DPPH和FRAP法相较于ABTS法,更适合表征桑葚发酵液的抗氧化活性变化情况。桑葚酒再经过40 d陈酿最终残还原糖为14.21 g/kg,乙醇浓度为101.6 g/kg,总酚含量2.124 g/kg,花青素含量579.4 mg/kg,类黄酮41.2 g/kg,DPPH自由基清除率为21.1%,FRAP抗氧化活性为40.9μmol Fe²⁺/L,总浸出物为23.241 g/L,符合国家相关标准,为进一步开发高生物活性桑葚精深加工产品提供了一条可行的途径。