Ascorbic acid and white wine production: a review of beneficial versus detrimental impacts

We review the use of ascorbic acid in winemaking and the benefits as well as the detrimental outcomes associated with its use. Initial discussion focuses on the antioxidant activity of ascorbic acid. The impact of the wine matrix and wine production practices, especially storage in bottle and oxygen ingress, on its antioxidant efficiency is discussed. The complementary roles of the antioxidant pair, ascorbic acid and sulfur dioxide, are presented. Thereafter, the ability of ascorbic acid to contribute to spoilage processes is covered. This includes both pro‐oxidant and non‐oxidative mechanisms induced by ascorbic acid that may lead to a reduced shelf life of white wine. Based on this review of scientific literature, the conditions most conducive to the beneficial impacts of ascorbic acid in wine are highlighted. Areas where lack of chemical knowledge still exists are identified for future research.     

Examination of the sulfur dioxide–ascorbic acid anti‐oxidant system in a model white wine matrix

The effectiveness of sulfur dioxide in inhibiting the ascorbic acid induced oxidation of (+)‐catechin in a matrix simulating white wine was investigated. At a sulfur dioxide:ascorbic acid mole ratio of 0.8:1.0, sulfur dioxide extended the delay prior to the onset of (+)‐catechin browning as measured by the increase in absorbance at 440 nm from 2 to 4 days post reaction initiation. The lengthening of the pre‐browning period was correlated with an increase in the time required to oxidise ascorbic acid completely, the sequence of events being loss of sulfur dioxide (day 3), loss of ascorbic acid (day 4) and on‐set of (+)‐catechin browning (day 4). Increasing the sulfur dioxide to ascorbic acid mole ratio to 3.0:1.0 inhibited the onset of (+)‐catechin browning over the 14‐day reaction period. This inhibition was achieved at considerable cost to the sulfur dioxide concentration, with the ratio of sulfur dioxide consumed to ascorbic acid oxidised being 1.7 compared with the expected fraction of 1.0. Reasons for the enhanced consumption of sulfur dioxide and the implications of this study for maintenance of quality in white wine production are discussed. Copyright © 2004 Society of Chemical Industry     

壳聚糖在白葡萄酒澄清中的应用研究

研究了壳聚糖在白葡萄酒澄清处理中的作用机理、应用条件、作用剂量及澄清效果，壳聚糖的应用有效地提高了白葡萄酒的澄清度、稳定性及光学效果。实验证明，壳聚糖对白葡萄酒的澄清作用效果明显优于明胶、皂土等常用的葡萄酒澄清剂。     

Browning susceptibility of white wine and antioxidant effect of glutathione

Glutathione (GSH) content and other physicochemical parameters of thirteen white wines originated from Lebanon were studied in relation to their browning capacity; the impact of pH, total sulphur dioxide and total phenol content into the browning susceptibility of the wine was shown. The effect of GSH, added to the wine at different concentrations, on the total phenol content was studied at 55 °C during 8 days of accelerated oxidation. GSH addition resulted in significantly higher total phenol content only on day 0 of the test. GSH was shown to be readily oxidised in these conditions: even on day 0, there was a considerable reduction (up to 73%) in GSH level. Moreover, after 8 days of oxidation, GSH concentration in all studied samples ranged from 4.79 to 5.11 mg L^?1; these values were close to GSH value in control wine (without added GSH) on day 0. On the contrary, GSH appeared to contribute significantly to the wine stability, which might have been via the increase of reduced phenolic pool. GSH addition appeared to have an improving effect on the organoleptic qualities of the wine.     

Copper(II)-mediated oxidation of (+)-catechin in a model white wine system

This study was undertaken to establish the role played by copper(II) in enhancing the rate of oxidation of flavanols. A model white wine system consisting of 12% (v/v) aqueous ethanol saturated with potassium hydrogen tartrate and adjusted to pH 3.2 was used to allow experimentation under well-defined conditions. (+)-Catechin was the oxidisable substrate and copper(II) concentrations up to 0.6 mg/L were employed. The model white wines were maintained at 45C to induce the browning process. Under these conditions an increase in absorbance at 440 nm occurred provided the copper(II) concentration was 0.3 mg/L or greater. The coloured species responsible for the increase in absorbance were identified as xanthylium cations, formed by linkage of two (+)-catechin molecules. Glyoxylic acid acted as the bridge between the phloroglucinol-type moiety of the (+)-catechin molecules. The production of the xanthylium cations was inhibited by ethanol and also by mannitol and the implications of these observations for a free-radical induced mechanism are discussed.     

酶法提高白葡萄酒质量稳定性的研究

利用木瓜蛋白酶水解白葡萄酒中非稳定蛋白,通过大量试验,确定了酶反应最佳条件为：加酶量为0．6％（w／v）,酶反应pH6．5,在45℃反应38h。此条件下,白葡萄酒中的蛋白含量降低为0．31g／L,氨基酸含量升高至6．7mg／L。     

Factors influencing the production and stability of xanthylium cation pigments in a model white wine system

The influence of various wine parameters on the production and stability of xanthylium cation pigments in a wine-like medium is reported. The xanthylium pigments have an absorbance maximum in the visible region at 440 nm that is close to the measured absorbance used by the wine industry to indicate the browning of wine (i.e. 420 nm). The results of this study show that iron is more efficient than copper in both the colouration and production of xanthylium cation pigments in wine-like solutions of tartaric acid and (+)-catechin. The non-flavonoid caffeic acid can inhibit the accumulation of the xanthylium cation pigments, despite the presence of metal ions, and also influence the stability of the pigment. Sunlight leads to a decrease in the concentration of xanthylium cation pigments while a temperature difference of 20 ^oC in the absence of light was observed to have little influence on concentration. The results suggest that the xanthylium cations are more likely to be a transitory species during white wine oxidation rather than accumulating pigments based on their instability with caffeic acid.     

Effect of using bentonite during fermentation on protein stabilisation and sensory properties of white wine

The bentonite use to remove proteins from white wine is a widespread practice that prevents protein haze formation after bottling. However, an excess of bentonite can have negative effects on both the aromatic profile of young white wines and the quality of the foam of sparkling wines. Therefore, the optimisation of bentonite amount to be used and the moment of its application during winemaking to minimise wine quality losses are of great interest for winemakers. This paper analyses how applying an equal bentonite dose at different stages (must clarification; beginning, middle and end of fermentation) on two scales (industrial and pilot) affects the protein content and stability, physical–chemical characteristics, aromatic profile and foam quality of the obtained wines. No important differences in the oenological parameters were observed between industrial and pilot scales, whereas the scale of the experimental treatments affected protein stability, aroma composition and foam quality of the wines.     

壳聚糖包埋皂土树脂提高白葡萄酒蛋白质稳定性

以壳聚糖和皂土为原料,制备了可回收的壳聚糖包埋皂土树脂,并研究了该树脂对白葡萄酒中蛋白质稳定性的影响.结果表明,该树脂在酒精-水混合体系中稳定,可用于白葡萄酒的澄清与稳定.当树脂使用量为1.00g/100mL酒样,温度15.0℃,间隔振荡36h时,葡萄酒稳定.树脂可重复使用3次,再生后仍能提高白葡萄酒的蛋白质稳定性.白葡萄酒经该树脂处理后,蛋白质含量降低约34%,总酚含量降低约30%,而对总糖、还原糖、酒精度和pH值没有显著性的影响.该实验为壳聚糖包埋皂土树脂应用于提高白葡萄酒的蛋白质稳定性提供了参考.     

干白葡萄酒酒精发酵过程中酵母菌生长周期研究

生产条件下，研究了干白葡萄酒酒精发酵过程中，巴杨氏酵平的生长周期和葡萄汁中糖分解过程。结果表明：低糖（２１０ｇ／Ｌ）葡萄汁进行酒精发酵过程中，酵母菌的生长周期可分为繁殖阶段，平衡阶段和衰减阶段三个时期，且平衡阶段与衰减阶段持续时间很短。     

新疆和田红干白葡萄酒香气成分分析

该研究以新疆和田地区酿酒葡萄“和田红”为原料进行工业化酿酒,利用固相微萃取和气相色谱质谱联用技术,研究和田红干白葡萄酒中的香气成分.结果表明:和田红干白葡萄酒中各项理化指标均符合国家标准,总酚含量为178.122mg/L;和田红干白葡萄酒中共鉴定出40种香气化合物,主要包括酯类(20种,占77.8％)、醇类(5种,占8.2％)和酸类(6种,占6.07％)化合物,酯类化合物含量最高,对其香气贡献最大.和田红干白葡萄酒中相对百分含量较高的香气化合物分别是辛酸乙酯、癸酸乙酯、己酸乙酯、乙醇、辛酸、3-甲基1-丁醇、癸酸、乙酸乙酯.     

不同酵母对干白葡萄酒发酵过程中香气变化的影响

选用两种酿酒酵母进行霞多丽干白葡萄酒发酵试验,酒精发酵过程中对发酵液的还原糖、可溶性固形物、总酸含量及香气物质进行分析。结果表明,两种酿酒酵母发酵过程中发酵液的还原糖和可溶性固形物均呈下降趋势,总酸含量均大于葡萄汁总酸含量;葡萄汁和发酵液中共检测出68种香气物质。相比于葡萄汁,酵母LA-DE和LA-PE发酵时发酵液中醇类、酯类、酸类、萜烯类和酚类物质含量随发酵时间延长逐渐增加,而醛类物质逐渐减少;其中酯类物质含量增加显著,发酵结束时分别为22.79 mg/L和14.57 mg/L。主成分分析结果表明,发酵过程中香气物质在前3 d变化较为明显,两种酵母发酵液在第1天、第3天、第9天香气物质差异明显。     

分散液液微萃取-液相色谱法测定白葡萄酒中拟除虫菊酯类农药

分散液液微萃取法处理样品,结合高效液相色谱测定白葡萄酒中拟除虫菊酯类(氟氯氰菊酯、氯氰菊酯、氰戊菊酯、联苯菊酯)农药残留.二氯甲烷作萃取剂,乙醇作分散剂.色谱条件:反相C18色谱柱,甲醇∶乙腈∶水(10∶75∶15,体积比)为流动相,流速1.0mL/min,210nm紫外检测.在0.05μg/mL～50.00μg/mL范围内线性良好.相关系数均大子0.9993.平均回收率为83.20％～102.71％,相对标准偏差为1.47％～3.24％,检出限为1.00μg/L～2.00μ g/L.     

三种酵母酿造霞多丽干白葡萄酒的效果研究

采用三种商品酵母AWRIR2、CY3079和EC1118进行霞多丽干白葡萄酒的发酵试验.结果表明:3种酵母发酵期的温度及比重变化一致,产酒精率相同,但AWRIR2酵母较其他两种酵母产生的挥发酸和残糖略高.采用GC/MS技术分别鉴定出3种酵母发酵的酒体中存在49、48和49种香气物质,其主要香气组分无差异,只在某些微量香气物质上有所区别.醇类、酸类、酯类及其他香气物质在3种酵母发酵的干白葡萄酒中的含量各有差异.     

大孔树脂对白葡萄酒中异戊醇的吸附动力学研究

该研究通过比较D101、D204、AB-8、X-5四种大孔树脂对白葡萄酒中异戊醇的吸附效果,选取最佳大孔树脂,并从动力学的角度对其吸附及解吸特性进行研究。结果表明,D101大孔树脂振荡吸附效果最佳,对异戊醇的吸附率达53%,其在体积分数为60%的乙醇中解吸48 h时对异戊醇的解吸率最高,达77%,具有良好的可重复利用性。D101大孔吸附树脂对白葡萄酒中异戊醇的吸附符合Langmuir吸附等温模型,可用准一级动力学吸附模型描述。采用流速为2 mL/min的体积分数为60%的乙醇对D101大孔树脂进行动态解吸时,36 h可达到最佳解吸效果,最大解吸率为84%。     

Biogenic amines in wine: a review

Biogenic amines are formed from precursor amino acids, mainly by the microbial decarboxylation. The presence of these compounds plays a vital role in oenology because high amounts of them can lead to health problems. Thus, the origin, detection, and quantity of biogenic amines in wine are extremely important for winemaking. This study, focusing on the articles of latest 5 years, not only reviews the analytical methods used for the determination of biogenic amines but also describes the source of biogenic amines from the perspective of microbiological and oenological factors and summarises the strategies for the degradation of amines. The information presented in this review is important to alert about the inadequate quality of wine products, and efforts from the entire productive chain and the government are required to attain consumer safety.