Effects of time of grape pomace fermentation and distillation cuts on the chemical composition of grape marcs

 The effects of fermentation time and distillation cuts on the composition of distillates in terms of ethanal, 1,1-diethoxyethane, methanol, 1-butanol, 2-butanol, 1-propanol, 2-methyl-1-propanol, 2-methyl-1-butanol, 3-methyl-1-butanol, ethyl acetate, ethyl 2-hydroxypropanoate, 3-methylbutyl acetate, hexyl acetate, 2-phenylethyl acetate, hexanol, trans-2-hexenol, trans-3-hexenol, cis-3-hexenol, 2-phenylethanol, ethyl butyrate, ethyl hexanoate, ethyl octanoate, ethyl decanoate, ethyl dodecanoate, 2-methylpropanoic acid, 3-methylbutanoic acid, hexanoic acid, octanoic acid, decanoic acid, and dodecanoic acid were assessed through data generated according to a factorial design using analysis of variance and principal component analysis. Four times of storage of pomace obtained following winemaking of two grape varieties of white Verde wine (Alvarinho and Loureiro) and three distillation cuts were considered; volatile compounds in the 24 samples generated were analyzed directly, and indirectly after extraction and concentration, by capillary gas chromatography. The results generated have suggested clear differences (P<0.05) between distillate cuts obtained throughout fermentation times for each grape variety. The major differences between the different distillate fractions analyzed were accounted for by the contents of diethyl butanoate, ethyl 2-hydroxypropanoate, and the sum of 3-methylbutanoic and 2-methylpropanoic acids for Loureiro, whereas the main differences were accounted for by the contents of diethyl butanoate and the sum of the carboxylic acids for Alvarinho. Received: 23 January 1998 / Revised version: 5 June 1998     

葡萄皮渣酿造葡萄醋过程中化学成分动态变化分析

利用葡萄皮渣发酵的葡萄酒醪进行醋酸发酵酿造葡萄醋,并研究发酵过程中化学成分的动态变化。采用GC-MS、氨基酸分析仪和原子吸收光谱对发酵过程中化学成分动态变化进行分析。结果表明:葡萄酒醪和葡萄醋的香气成分的种类相似,主要为酯类和醇类（主要是琥珀酸单乙酯和苯乙醇）;葡萄酒醪与葡萄醋氨基酸的种类和含量都相差较大,葡萄酒醪有15种氨基酸,葡萄醋只有5种氨基酸;检测的8种金属元素在葡萄酒醪和葡萄醋中差异不大。      

发酵法活化葡萄皮渣膳食纤维工艺的研究

以葡萄酒厂的副产物-葡萄皮渣为原料,采用嗜热链球菌和保加利亚乳杆菌混合发酵技术活化其中的膳食纤维,提高了葡萄皮渣中可溶性膳食纤维的含量。经正交试验得到乳酸菌发酵活化葡萄皮渣膳食纤维的最佳反应条件为：液料比10：1（v／w）,菌种比1：1（v／v）,发酵温度42℃,发酵时间12h,接种量10％,产品SDF含量为19．54％（干基）,较原料中SDF提高3．6倍。     

Effects of red-wine grape pomace on the quality and sensory attributes of beef hamburger patty

This study was conducted to evaluate the effect of red-wine grape pomaces on the quality and sensory attributes of beef hamburger patties. Both phenolic content and antioxidant activity were assessed using Syrah, Merlot and Cabernet Sauvignon pomaces. Following the assessment, hamburger patties were prepared with Merlot pomace at 0%, 2% and 4% for the patty quality and sensory attributes. Grape seeds possessed significantly higher phenolics and antioxidant activities over the seedless pomace (P < 0.05), whereas no significant difference was found for phenolics and antioxidant activities within the seeds and seedless pomaces. The patty pH decreased as the pomace was added for 2% and 4%. Colour values (L*, a* and b*) of patties lowered as the pomace was added. Allo-Kramer shear force and hardness values increased while cooking yield decreased (P < 0.05) with the addition of pomace. No significant difference between control and Merlot patties was found for flavour, juiciness and colour, whereas lower sensory attributes were observed for texture, taste and overall acceptability. It is observed that the addition of fermented red-wine grape pomace provides hamburger patties with health promoting factors such as antioxidant and other functional components, but it also provided darker, sourer and lower cooking yield.     

Functional components of grape pomace: their composition,biological properties and potential applications

The roles of functional foods on human health have been realised by more and more researchers, food producers and consumers. Functional food ingredients from both plant and animal sources such as dietary fibre, soy protein isolate, whey protein isolate and omega 3 fatty acid have been widely used in functional food product development. Many fruit processing by‐products such as grape, apple and orange peels are rich in bioactive phytochemicals, dietary fibre and unsaturated fatty acids, hence have potential to serve as functional food ingredients. In this review, we summarise recent advancement of research in grape pomace (GP), the residual of grapes after wine making. The polyphenol profile of GP and their biological, antioxidant and antimicrobial activities, the stability of GP polyphenols in food system, the interaction between GP polyphenol and other food ingredients, as well as the functionalities of grape seed oil and GP fibre are covered.     

Chemical composition of dietary fiber and polyphenols of five different varieties of wine grape pomace skins

The skins of two white wine grape pomace (WWGP) and three red wine grape pomace (RWGP) from US Pacific Northwest were analyzed for their dietary fiber (DF) and phenolic composition. DF was measured by gravimetric–enzymatic method with sugar profiling by HPLC–ELSD. Insoluble DF composed of Klason lignin (7.9–36.1% DM), neutral sugars (4.9–14.6% DM), and uronic acid (3.6–8.5% DM) weighed more than 95.5% of total DF in all five WGP varieties. WWGP was significantly lower in DF (17.3–28.0% DM) than those of RWGP (51.1–56.3%), but extremely higher in soluble sugar (55.8–77.5% DM vs. 1.3–1.7% DM) (p < 0.05). Soluble polyphenols were extracted by acidified 70% acetone and measured spectrophotometrically. Compared with WWGP, RWGP had higher values in total phenolic content (21.4–26.7 mg GAE/g DM vs. 11.6–15.8 mg GAE/g DM) and DPPH radical scavenging activity (32.2–40.2 mg AAE/g DM vs. 20.5–25.6 mg AAE/g DM) (p < 0.05). The total flavanol and proanthocyanidin contents were ranged from 31.0 to 61.2 mg CE/g DM and 8.0 to 24.1 mg/g DM, respectively for the five WGP varieties. This study demonstrated that the skins of WGP can be ideal sources of DF rich in bioactive compounds.     

Applicability of enzymatic extracts obtained by solid state fermentation on grape pomace and orange peels mixtures in must clarification

Grape pomace, a residue produced in the wine industry, is becoming an environmental problem. By other hand enzymes extracts are products of great value in the wine making. In this work we evaluated applicability in must clarification of an enzyme extract produced by solid state fermentation on a mixture of grape pomace and orange peel. Before using the enzyme extracts, lyophilisation and different methods of protein precipitation were tested in order to concentrate exo-PG and xylanase. Our results showed that ethanol precipitation at −20 °C was the most adequate method, obtaining efficiencies of 50.2% and 39.2% for exo-PG and xylanase, respectively. This concentrated protein extract was used for clarification of must, giving a decrease of 97.5% respect to the initial turbidimetry after 40 h of incubation, which improved the clarification obtained with other commercial crude enzymes. Exo-PG and xylanase contained in our protein extracts were very stable at different temperatures, pH and in the presence of different cations. Finally, exo-PG and xylanase were partially purified by anion exchange chromatography on DEAE-cellulose column obtaining enrichments of 35.5- and 5.5-fold respectively over the culture supernatant. All these results suggested the promising application in juice and wine industries of the concentrated extracts with high levels of exo-PG and xylanase obtained by the proposed method.     

不同氨基酸对模拟葡萄汁发酵的影响

该研究在酿酒酵母（Saccharomyces cerevisiae）发酵模拟葡萄汁进入稳定期时分别补加18种氨基酸,通过分析酿酒酵母生长、发酵速率以及最终乙醇、有机酸和高级醇含量的变化,比较不同氨基酸对葡萄酒发酵的影响。结果表明,丙氨酸（Ala）和缬氨酸（Val）能显著增加酿酒酵母的生物量和发酵速率以及最终乙醇和异丁醇含量（P＜0.05）,对有机酸含量影响较小。高质量浓度的半胱氨酸（Cys）（200 mg N/L）和赖氨酸（Lys）（200 mg N/L）抑制酿酒酵母生长和发酵速率,显著增加了有机酸含量（P＜0.05）。蛋氨酸（Met）抑制酿酒酵母的发酵速率,产生了大量的3-甲硫基丙醇。因此,对发酵有积极影响的Ala和Val比较适合作为葡萄酒酿造过程中的补加氮源,反之,Cys、Lys和Met不适合作为补加氮源。     

酿酒葡萄皮渣中多酚物质提取的研究

以酿酒后分离的葡萄皮渣为原料,对其多酚类物质的提取条件进行了研究。在单因素试验的基础上,以乙醇体积分数、料液比、浸提时间、浸提温度为影响因素,以葡萄皮多酚得率为评价指标,进行4因素3水平正交试验,确定出的最佳浸提条件为浸提剂为体积分数70%的乙醇,浸提温度80 ℃,浸提时间40 min,按1∶7（g∶mL）的料液比,浸提次数为3次,在此条件下,葡萄皮渣中多酚提取量为30.03 mg/g。     

The evaluation of grape pomace distillates from selected red grape varieties

This report describes the composition of the volatiles from grape pomace distillated that are commercially available in Greece. These spirits, which are a valuable by‐product of the winemaking industry, were obtained by distillation of grape pomace after fermentation under anaerobic conditions. The volatiles were distilled twice. Each distillate was separated in to 4 equal (by volume) fractions and the changes in volatile concentration during distillation were measured. Assays were done by gas/liquid chromatography (for alcohols, carboxylic acids, esters and aldehydes). The average values for volatile concentrations obtained for Greek grape pomace distillates were compared with the corresponding values for grape pomace manufactured in other Mediterranean countries.     

葡萄酒糟色素提取工艺研究

对葡萄酒糟色素的提取工艺作了初步研究,确定了葡萄酒糟色素的最大光吸收值为530nm.通过溶剂法提取工艺在单因素水平基础上进行的研究表明,葡萄酒糟与提取液之比为1:5提取效果最好;在酸性条件下提取效果比在碱性条件下好;温度对葡萄酒糟色素提取效果的影响较大;确定了最佳提取剂为80%乙醇水溶液以及最佳提取时间为3h.通过正交实验对提取工艺条件进行优化,确定的最佳工艺参数如下:提取溶剂为80%乙醇水溶液,溶液pH为4,提取温度为60℃,提取时间为3h.通过薄层层析法(TLC)初步探索出可用三氯甲烷或乙酸乙酯与冰醋酸的混合液作为葡萄酒糟色素柱层析的溶剂系统.     

桑椹酒人工发酵过程中化学成分变化的研究

研究了桑椹酒人工发酵过程中一些主要成分如总糖、总酸、挥发酸、单宁、乙醇、甲醇、高级醇和酯等物质含量的变化。结果表明,桑椹通过加糖发酵原酒酒度可达到12.0%vol,总酸6.83g/L,pH3.12;单宁含量基本上无变化;挥发酸含量随着发酵时间的延长而逐渐上升,但最终可控制在1.0g/L(国标≤1.2g/L);甲醇在刚开始发酵时就存在,且含量维持在相对稳定的水平;高级醇主要包括正丙醇、异丁醇和异戊醇3种,占香气成分的50%,且在发酵过程中不断增加;发酵过程中还检测到乙醛、乙酸乙酯、己酸乙酯、戊酸乙酯、乳酸乙酯和一些未知成分。     

Influence of sour rotten grapes on the chemical composition and quality of grape must and wine

This study evaluated the effect of grape sour rot on wine fermentation and characterized the chemical composition and the sensory changes in wines produced from rotten musts. Microvinifications were performed during two vintages using healthy Trincadeira and Cabernet Sauvignon red grape varieties to which were added grapes affected by sour rot. Increasing sour rot percentages, up to 50%, contributed to a clear decrease in free run must and final wine yields and induced significant changes in grape must chemical composition expressed by the increase in sugar content, total acidity, volatile acidity, anthocyanins, total phenols, and color intensity. After malolactic fermentation, wines from rotten grapes showed higher values of alcohol content, dry extract, reducing sugar content, total and volatile acidity, anthocyanins, total phenols, and color intensity. Despite the higher levels of reducing sugars, the microbial stability was similar to that of healthy wines. The sensorial evaluation, after malolactic fermentation, showed that both types of wine were not statistically different regarding color, aroma, taste, and overall quality. During 6–8 month storage, wines from rotten grapes showed a significant higher percentage of color loss, suggesting that sour rot is responsible for the decrease in color stability. Nevertheless, the results of sensorial analysis demonstrated that the fermentation of grape musts containing up to 30% sour rot yields wines with similar or even higher-quality scores than wines made with healthy grapes.