几种澄清剂对黑莓果酒中蛋白质的影响

果酒中的蛋白质是果酒产生浑浊沉淀的主要原因之一。本研究分析了常用的几种单一澄清剂及复合澄清剂对黑莓果酒中蛋白质含量的影响。响应面分析结果表明最佳澄清剂为明胶-单宁复合澄清剂,其添加量为明胶1.32 mL/100 mL,单宁0.41 mL/100 mL,此时黑莓酒的蛋白质含量降至96.96 mg/L,蛋白质的去除率达到25.0%,透光率达到91.8%,总酚含量下降了35.8%,总糖含量以及色度变化微弱。     

Analysis of tannins in seeds and skins of Shiraz grapes throughout berry development

The flavan-3-ol and proanthocyanidin composition of both seeds and skin of Vitis vinifera L. cv. Shiraz grapes was determined by reversed-phase HPLC after acetone extraction and acid-catalysis in the presence of excess phloroglucinol. Samples were taken at weekly intervals from fruit-set until commercial harvest. The main period of proanthocyanidin accumulation in grape seeds occurred immediately after fruit-set with maximum levels observed around veraison. Over two seasons there was variation in both the timing and content of proanthocyanidins in seeds. In skin, proanthocyanidin accumulation occurred from fruit set until 1–2 weeks after veraison. Proanthocyanidin subunit composition was different in seeds and skin and changed during berry development but the mean degree of polymerisation of the tannin polymers in skins was higher than in the seeds at all stages of berry development. Proanthocyanidin levels in both seeds and skin decreased between veraison and harvest. Additional proanthocyanidin subunits were released when the residues remaining after acetone extraction were subjected to direct acid-catalysis in the presence of phloroglucinol. In the seeds, these accounted for much of the post-veraison decrease, but not in grape skin. At harvest, 75% of extractable berry proanthocyanidin was in the seeds. Accumulation of proanthocyanidins in the seeds appears to be independent of that in the skins, but in both tissues synthesis occurs early in berry development and maximum levels are reached around veraison.     

单宁对白酒发酵影响的实验室分析研究

采用三角瓶和陶坛两种固态发酵方式分别模拟白酒发酵过程,通过向高粱中单独添加一定量的单宁单体成分,探究单宁成分对白酒固态发酵的影响.酒醅理化方面,在20d的发酵结束后空白组酒醅水分含量升高3.78％、酸度升高1.1 mmol/10 g、淀粉含量下降2.09％、还原糖含量下降0.67％,而添加单宁的两组酒醅水分含量仅分别升...     

可降解橡碗单宁产鞣花酸的菌种筛选

以COD去除率为指标 ,筛选出可降解橡碗单宁的微生物菌株 ,其COD去除率为5 9%。通过对该菌株产鞣花酸的单因素优化条件研究结果表明 ,该菌株产鞣花酸的最适条件为 :培养温度 30℃ ,培养时间 4d ,2 5 0mL锥形瓶中的装瓶量为 15 0mL ,发酵培养基 (NaNO32 0 g/L ,K2 HPO4 1 0 g/L ,MgSO4 0 5 g/L ,FeSO4 0 0 1g/L ,橡碗单宁 5 g/L ,葡萄糖 30g/L)中单宁浓度为 5 g/L ,pH值 5 0。在此最适条件下鞣花酸产率可达 7 7%。经鉴定 ,该菌株属于半子囊菌纲 ,内胞霉目 ,内胞霉科 ,内胞霉属。     

响应面法优化蓝靛果酒低温二氧化碳浸渍工艺

以蓝靛果为原料,对蓝靛果酒低温CO2浸渍工艺进行优化。研究浸渍时间、浸渍温度和浸渍压力对蓝靛果酒品质的影响,在单因素试验的基础上以蓝靛果酒感官评分为响应值进行响应曲面的优化设计。得到最佳的浸渍工艺为:浸渍时间5.6 d、浸渍温度6℃、浸渍压力0.1 MPa,此条件下蓝靛果酒的感官评分为91,色泽鲜红,口味柔和,香气浓郁,具有独特的风味。通过对比试验,对果酒的主要理化指标进行测定,并进行感官评价。试验表明,低温CO2浸渍工艺能降低蓝靛果酒中总酸和单宁的含量,并且能保证花色苷等酚类物质的有效浸出。     

Kinetics of ultrasonic extraction of polyphenols,anthocyanins and tannins from five different New Zealand grape pomaces

Polyphenols were extracted from five kinds of New Zealand grape pomace (Sauvignon Blanc, Pinot Gris, Gerwurztraminer, Merlot and Pinot Noir) at 30, 50 and 70 °C in an ultrasonic generator. The extraction kinetics for total phenol, anthocyanin and tannin were determined. The results of dynamics study showed that the extraction of total polyphenols, anthocyanin and tannin followed first-order reaction kinetics during the extraction at 30, 50 and 70 °C. The total phenolic content, anthocyanin conten, and tannin content of water–ethanol extracts from grape pomaces were compared, and the parameters in the extraction kinetics equations were determined. The extraction results showed that the Pinot Noir pomace extract had the highest total phenolic content of 59.95 mg GAE g⁻¹ pomace and tannin content of 79.93 mg EE g⁻¹ pomace. The anthocyanin content in Merlot pomace extract was the highest, which was 4.50 CE g⁻¹ pomace. The results might be of great significance for the development of grape pomace or its polyphenol and/or anthocyanin components as an antioxidant source with natural and inexpensive benefits.     

Astringency sub-qualities of red wines and the influence of wine–saliva aggregates

Astringency is a sensory attribute, related to the quality and mouthfeel of red wines. However, the origin of astringency sub-qualities, such as the typical drying astringency found in immature grapes, is still unknown. Astringency of red wines with similar tannin content but different astringency sub-qualities, from different harvest dates, is studied. Astringency was characterised in terms of friction coefficient, polyphenol content, sensory analysis and tannin/salivary–proteins aggregates characterisation. A different evolution during ripening was found for both Cabernet Sauvignon and Carménère, and tannin–protein aggregates showed differences in size, shape and surface. The velvety sub-quality appears to be related to aggregates with low precipitation, and with specific surface characteristics as roundness and Feret diameter. Results from this work propose an effect of aggregates on sensory perception and opens the possibility to explore their effect on oral lubrication.     

The role of acidity,sweetness, tannin and consumer knowledge on wine and food match perceptions

The purposes of this study were to (1) explore significant differences in perception of match for a variety of food and wine styles; (2) evaluate the impacts of wine sweetness level, wine acidity level, and wine tannin level on perception of match; and (3) investigate the impact of food and wine expertise on perceived level of match. The highest perceived wine matches for each food item were: Sauvignon Blanc and chêvre, Chardonnay and brie, Cabernet Sauvignon and spicy Italian salami, and Port and milk chocolate. Wine sweetness, acidity, and tannin levels all significantly impacted the level of match with certain food items. Food and wine expertise also significantly impacted the level of match, indicating differences between the more expert and novice participants in the role wine sweetness, acidity, and tannin had on level of match.     

Ion Exchange Resin Applied to Obtain Clarified Cashew Juice

The condensed tannins present in cashew apple juice provide high astringency, which is undesirable for this product. This study aimed to remove the cashew apple juice tannins by ion exchange for obtaining the clarified cashew apple juice (cajuína). Two strong base resins were used (macroporous and gel type). The effect of the process variables: temperature, resin:juice ratio, and stirring speed were determined. The macroporous resin presented better results with condensed tannins removal up to 80% in optimal conditions (30°C, ratio 1:6, 122 rpm). The cajuína obtained was clear and translucent, with low astringency, acidity, and °Brix according to Brazilian legislation.