Effect of clarification on the fatty acid composition of grape must and the fermentation kinetics of white wines

 The effect of different static and dynamic clarification treatments on grape must used in the manufacture of white wines was studied. Turbidity, yeast populations in the musts and must lees, fatty acid composition of the must and must lees after each treatment, and the fermentation kinetics using each cleaned must were measured. Fatty acids not previously found in grape must, such as tridecanoic acid and myristoleic acid, were detected. Dynamic clarification prolonged fermentation, and certain long-chain fatty acids helped activate fermentation. Received: 5 October 1998 / Revised version: 8 February 1999     

Discrimination of Chinese rice wines of different geographical origins by UV–vis spectroscopy and chemometrics

Discrimination of Chinese rice wines from four geographical origins (‘Zhejiang’, ‘Jiangsu’, ‘Shanghai’ and “Fujian”) in China was investigated according to their UV–vis spectra. The UV–vis absorption spectra of 112 samples in the wavelength range of 190–800 nm were collected. Then the absorption data was subjected to principal component analysis to reveal differences between samples and the potential possibility of using multivariate methods to distinguish differences. Classification models were developed by soft independent modelling of class analogy, linear discriminate analysis (LDA), discriminant partial least squares and support vector machine. Seven mathematical pre‐treatments were applied to improve the performance of the multivariate classification models. Among the seven pre‐treatments, standard normal transformation (SNV) was superior to the other six methods. The results showed that, compared with other models, SNV‐treated LDA models achieved better performances with an average correct classification rate of 98.96% in the training set and 100% in the testing set. The results demonstrate that UV spectroscopy combined with chemometric data analysis, as a rapid method to classify Chinese rice wines according to their geographical origins, is feasible. Copyright © 2015 The Institute of Brewing & Distilling     

辐照处理对鲜切胡萝卜贮藏品质变化研究

目的 研究辐照处理对鲜切胡萝卜贮藏品质变化的影响。方法 将鲜切胡萝卜经不同剂量(1.0、1.5、2.0、2.5、3.0 kGy)60Coγ射线辐照处理后, 于室温20 ℃贮藏, 在0、3、7、10 d测量其营养品质指标和生理生化指标。结果 60Coγ射线辐照处理对鲜切胡萝卜中可溶性糖含量和可溶性蛋白含量基本无影响; 1.0、1.5、2.0 kGy剂量的60Coγ射线辐照处理可较好地保持鲜切胡萝卜的还原糖含量、类胡萝卜素含量、维生素C含量, 其中1.5 kGy剂量处理效果最好; 于20 ℃贮藏, 1.5、2.0 kGy剂量的60Coγ射线辐照处理可较好地保持鲜切胡萝卜的可溶性固形物含量, 抑制多酚氧化酶的活性; 1.0、1.5 kGy剂量的60Coγ射线辐照处理可较好地抑制过氧化物酶的活性。结论 综合60Coγ射线辐照对鲜切胡萝卜各项指标的影响, 确定1.5 kGy是较适宜的剂量。     

Effects of Vinification Techniques Combined with UV‐C Irradiation on Phenolic Contents of Red Wines

Red wines are typically high in phenolic and antioxidant capacity and both of which can be increased by vinification techniques. This study employed 3 vinification techniques to assess the increase in phenolic compounds and antioxidant capacity. Wines were obtained from Bo?azkere grape cultivar by techniques of classical maceration, cold maceration combined with ultraviolet light (UV) irradiation, and thermovinification combined with UV irradiation and changes in phenolic contents were examined. Total phenolic and anthocyanin contents and trolox equivalent antioxidant capacity of wines were measured spectrophotometrically and phenolic contents (+)‐catechin, (–)‐epicatechin, rutin, quercetin, trans‐resveratrol, and cis‐resveratrol were measured by High Pressure Liquid Chromatography with Diode Array Detection (HPLC‐DAD). As a result of the study, the highest phenolic content except for quercetin was measured in the wines obtained by thermovinification combined with UV irradiation. We demonstrated that the highest phenolic compounds with health effect, total phenolic compounds, total anthocyanin, and antioxidant activity were obtained from thermovinification with UV‐C treatment than classical wine making.     

Effect of UV‐B treatment during the growth process on the postharvest quality of mung bean sprouts (Vigna radiata)

The production patterns and nutritious qualities of mung bean sprouts are in line with the consumption needs of modern people. This study was conducted to explore the effects of low doses of UV‐B irradiation on the 3‐day growth period of mung bean sprouts. The results showed that, when mung bean sprouts were irradiated with UV‐B (0.738 kJ m^?2) for 1 h per day, their total phenolic content increased by 22.80%, and the activity of polyphenol oxidase decreased by 45.45%. Hypocotyl epidermis stomata were closed, reducing water loss and the opportunity for microbes to invade plants, leading to the maintenance of freshness of the sprouts. In conclusion, UV‐B irradiation for 1 h per day during the growth of mung bean sprouts can effectively improve their preservation. This method is a low‐cost, environmental friendly and pollution‐free physical preservation technique, and it has good application prospects.     

Sensory and chemical characteristics of trans‐resveratrol‐fortified wine

Background and Aims: trans‐Resveratrol (tR) is a grape‐derived polyphenolic that is believed to confer considerable health benefits to humans. Its concentration in wine, however, is highly variable, and thus direct fortification of wine with tR has been proposed to create a high‐value, health‐promoting wine product. This study determines the sensory and chemical characteristics of tR fortified white and red wine. Methods and Results: Riesling and Cabernet Sauvignon wines were enriched with 20 mg/L and 200 mg/L tR. Basic chemical and sensory indicators of wine quality, trans‐ and cis‐resveratrol concentrations, and antioxidant capacity were assessed at bottling and at 6, 18, 31, 44 and 58 weeks post‐bottling. tR concentrations in bottled wine remained relatively stable throughout the 58‐week period of this study. In addition, tR‐enriched wines had a significantly higher antioxidant capacity compared with control wine, and Cabernet Sauvignon fortified at both tR concentrations had greater colour intensity. Basic chemical indicators of wine quality were not affected by tR fortification, and sensory changes were minimal, with higher bitterness intensity in Riesling fortified at 200 mg/L tR the most consistent finding. Conclusions: tR is relatively stable in wine during bottle aging, and tR enrichment up to 200 mg/L results in minimal change to wine quality, particularly with red wine. Significance of Study: This is the first study to investigate the chemical and sensory characteristics of tR‐enriched wines. Results indicate that these products may have considerable potential for the functional food market.     

橡木片陈酿对赤霞珠干红葡萄酒品质的影响

为了提高橡木片陈酿赤霞珠干红葡萄酒品质,设计橡木片添加量分别为0、4 g/L、6 g/L、8 g/L和10 g/L的5个不同处理组,未加橡木片的为对照组,陈酿期间通过定期测定各组色度、色调值以及花色苷、单宁和总酚含量等理化指标的变化,并结合干红葡萄酒感官品质评定,确定橡木片最佳添加量。结果表明,对赤霞珠干红葡萄酒橡木片陈酿时,橡木片最佳添加量为6 g/L、陈酿时间为45 d。在此种陈酿方式下,葡萄酒的理化指标和感官品质可得到明显改善和提升。     

外源抗氧化剂对荔枝酒发酵的影响研究

为了解决过量二氧化硫影响果酒品质的问题,探索二氧化硫的取代物,考察了添加二氧化硫、抗坏血酸、异抗坏血酸、谷胱甘肽和乙二胺四乙酸（EDTA）对荔枝酒中多酚氧化酶（PPO）、过氧化物酶（POD）、总糖、总酸、酒精度、杂醇油和总酯的影响。结果显示,添加抗氧化剂有利于抑制酶活、促进香气物质的生成。在抗氧化剂添加量为250 mg/L时,添加异抗坏血酸比添加SO2的酒样中PPO酶活、POD酶活、总糖分别降低了70.0%、66.7%、79.4%,而酒精度、杂醇油、总酯分别提高了3.8%、16.5%、61.4%;添加EDTA比添加SO2的酒样中PPO酶活、POD酶活、总糖分别降低了60.0%、58.3%、75.0%,而酒精度、杂醇油、总酯分别提高了1.9%、10.8%、57.1%。研究表明,添加异抗坏血酸或乙二胺四乙酸可以部分的取代二氧化硫,有利于提升荔枝酒的品质。     

Consumer acceptability,sensory properties and expert quality judgements of Australian Cabernet Sauvignon and Shiraz wines

Background and Aims: This study aimed to determine what sensory attributes most drive consumer and expert acceptance for Cabernet Sauvignon and Shiraz wines. Methods and Results: The sensory attributes of a set of commercial wines were quantified by a trained panel. A subset was assessed blind for liking by 203 consumers and for quality by 67 winemakers. For the total group of consumers, wines with low levels of ‘bitterness’, ‘hotness’, ‘metallic’, ‘smoky’ and ‘pepper’ were preferred. In addition, four consumer clusters were identified, each with different sensory drivers of preference, with the attributes ‘red berry’, ‘floral’, ‘caramel’ and ‘vanilla’ aroma, ‘acidity’, ‘green’ flavour and astringency being of importance in distinguishing the different clusters' acceptance scores. The winemakers' quality scores had little relationship with consumer response, although both groups gave low ratings to wines with Brettanomyces-related flavour. Conclusions: A relatively small set of sensory attributes were of greatest importance to consumer liking, and these generally dominate varietal differences. Winemakers' quality concepts do not closely align with those of the consumers. Significance of the Study: This study identifies sensory properties of red wines which could be maximised as well as those which should be reduced, allowing producers to better meet consumers' preferences.     

UV‐C irradiation reduces breakdown and chilling injury of peaches during cold storage

Pre‐storage exposure of peaches (Prunus persica cv Jefferson) with UV‐C irradiation for 3, 5 or 10 min significantly reduced chilling injury after 14 and 21 days of storage at 5 °C plus 7 days of shelf‐life at 20 °C. Similar reduction in fungal decay was also found by these treatments. Skin browning and UV damage were found to be moderate to severe in peaches after the 15 or 20 min of UV‐C treatments. The 20 min of exposure accelerated deterioration. Fruit treated with UV‐C for 3, 5 or 10 min remained firmer and softened more slowly than the control and those treated with longer durations of exposure. No differences were found in weight loss or respiration rates among the treatments. However, ethylene production was stimulated by all of the UV‐C treatments compared with the control. Putrescine levels increased initially after 3 or 5 min of exposure to UV‐C. A tendency toward higher accumulation of spermidine and spermine was found in peaches after UV exposure. These higher levels of polyamines apparently are a response to the UV‐C irradiation and might be beneficial in increasing the resistance of fruit tissue to deterioration and chilling injury. Copyright © 2004 Society of Chemical Industry     

原料品种和制浆方法对枣酒多酚含量和感官品质的影响

为了探讨枣品种和制浆方法对枣酒多酚含量以及感官品质的影响,在固定基本发酵工艺和配方的前提下,以7种红枣、2种制浆方法进行枣酒酿制,分析多酚含量和感官指标,研究原料和制浆方法对枣酒多酚含量及感官品质的影响。陕西陕北狗头枣、山东日照枣、山西太行山枣、山西柳林摊枣、河南灵宝枣、河北金丝小枣和新疆和田枣所酿枣酒的多酚含量和感官评分依次平行降低;低温烘干粉碎后调浆比直接打浆明显有利于提高枣酒的多酚含量和感官品质。结果表明,原料选择和制浆方法对枣酒多酚含量和感官品质具有不容忽视的影响;枣酒多酚含量与感官品质显著正相关。     

Effect of low‐energy X‐ray irradiation on physical,chemical, textural and sensory properties of Dates

The effect of X‐ray irradiation as postharvest treatment on physical, chemical, textural and sensory attributes of Khalas dates (Phoenix dactylifera L.) was investigated. The surface of dates was subjected to low‐energy X‐ray irradiation at 3, 5 and 7 KGy. While some physical and chemical properties of dates were significantly different between treatments (fruit hardness, crude protein, total fat, tannins, total fibre and insoluble fibre), there was no detrimental effect on the quality (crude fibre, soluble dietary fibre, sucrose, glucose, fructose, moisture, total soluble solids, pH, water activity, colour and sensory evaluation). The sensory acceptability of X‐ray irradiated dates was significantly lower at 5 and 7 KGy than for untreated control. Irradiation at 3 KGy did not contribute to significant changes in physical, chemical or textural properties of dates. Adaptation to low‐energy X‐ray irradiation can be used as a potential commercial treatment for retaining the quality and ensuring the safety of dates.     

紫外线照射处理对馒头品质及保质期影响研究

目的研究紫外线照射处理的方法对馒头品质及保质期的影响。方法通过对馒头进行感官评价确定馒头的品质,通过测定馒头表面的微生物数量确定馒头的保质期。结果紫外线照射时间和紫外照射灯管数能够明显延长馒头的保质期。在紫外线照射时间7 s,紫外灯管数3根,紫外照射距离为5 cm时,微生物生长受到明显抑制,馒头的保质时间从20 h延长至40 h,而且对馒头的感官评价基本没有影响,具有良好的安全性。结论紫外线照射处理对馒头的品质影响较小,但能够明显延长馒头的保质期。     

Effect of Esca disease on the phenolic and sensory attributes of Cabernet Sauvignon grapes,musts and wines

Background and Aims: The impact of Esca, a cryptogamic disease affecting woody tissues of grapevines (trunk, branches and shoots), was investigated on phenolic and sensory qualities of Cabernet Sauvignon grapes, derived musts and wines. Methods and Results: Global phenolic analyses revealed no major difference between healthy and affected grapes whereas high‐performance liquid chromatography analyses showed decreases in the skin concentrations of catechin and epicatechin and of anthocyanins for the two vintages assessed. Proanthocyanidin characteristics, and particularly mean degree of polymerisation, were strongly decreased in skin proanthocyanidin polymeric fractions. Chemical analyses of wines made with different percentages of fruit from Esca infected grapevines confirmed the moderate impact of Esca on phenolic composition. Nevertheless, sensory analyses revealed a loss of wine sensory quality perceptible with as little as 5% of affected fruit in wines. Conclusions: Phenolic variations in grapes and in derived wines may be related to changes to grapevine physiology caused by Esca fungi that impact on flavonoid metabolism. The chemical and sensory variations between wines can also be related to the delayed ripening delay of fruit from Esca infected grapevines. Significance of the Study: Esca moderately affected the phenolic composition of grapes and decreased the sensory quality of wines, suggesting a dramatic increase in the economic importance of Esca if no control methods are found.     

美极梅奇酵母对迟采赤霞珠葡萄酒品质的影响

以云南德钦产区的迟采赤霞珠葡萄为原料,选用实验室筛选的美极梅奇酵母（Metschnikowia pulcherrima）MP3007与商品酿酒酵母（Saccharomyces cerevisiae）CY3079混合发酵,以酿酒酵母纯发酵为对照,研究不同发酵方式以及美极梅奇酵母对迟采赤霞珠葡萄酒挥发性香气物质和感官品质的影响。结果表明,混合发酵对迟采葡萄酒的感官品质提升作用明显,混合清汁发酵可以降低葡萄酒中31.7%的挥发酸含量,14.5%的总酸含量以及4.1%的酒精含量;混合浸渍发酵时可以降低葡萄酒中25.6%的挥发酸含量,8.4%的总酸含量以及5.1%的酒精含量。同时,混合发酵还会增加葡萄酒中乙酸异戊酯、辛酸乙酯以及异戊醇、2,3-丁二醇的含量,降低辛酸含量;葡萄酒浆果味提升且生青味降低。初步认为美极梅奇酵母MP3007在迟采葡萄酒酿造领域具有应用潜力。