Effect of sulphur dioxide and must extraction on colour,phenolic composition and sensory quality of red table wine

Red wines were made during 1992 from Vitis vinifera var Roriz grapes using a high and a low level of extraction and three levels of total sulphur dioxide (0, 75 and 150 mg SO₂ kg⁻¹). From this single experiment, the effects of total SO₂ and extraction on anthocyanin composition and colour were observed by HPLC, spectrophotometry and tristimulus colorimetry. High extraction produced a wine with more total pigments and total phenols than low extraction and increased the amount of organic acids extracted during fermentation. More anthocyanins were extracted with increasing SO₂ levels. On maturation, all wines lost colour and increased in brownness. Wines made without SO₂ browned more than the wines made with SO₂. The anthocyanins normally present in wines were all rapidly lost to trace levels at 24 months. Vitisin A, a more stable and highly coloured anthocyanin than malvidin 3-glucoside, showed a slower decrease in concentration than malvidin 3-glucoside and contributed significantly to the wine colour during aging. At the first analysis, the wines made without SO₂ had a higher percentage colour due to polymers than the wines made with SO₂. Polymerisation progressed during maturation, although the initial differences were maintained. Sensory analysis after 6 and 18 months storage by expert tasters revealed differences mainly related to the colour attributes, indicating that when wines are made using modern hygienic techniques, total SO₂ has a negligible effect on aroma and flavour attributes. © 1998 Society of Chemical Industry.     

Use of unripe grapes harvested during cluster thinning as a method for reducing alcohol content and pH of wine

Background and Aims: Deep red full‐bodied wines can only be obtained from grapes with complete phenolic maturity, which frequently produce wines with high pH and alcohol content. The present study focuses on a new procedure for simultaneously reducing pH and ethanol content. Methods and Results: Grapes from cluster thinning were used to produce a very acidic low‐alcohol wine. The wine was treated with high doses of charcoal and bentonite. This odourless and colourless wine was used to reduce pH and ethanol content of wine produced from grapes, which had reached complete phenolic maturity. The anthocyanin and proanthocyanidin concentrations, the mean degree of polymerisation and the monomeric composition of proanthocyanidin of reduced‐alcohol wines were similar to those of their corresponding controls. Since the pH was lower, the colour of the reduced‐alcohol wines was more intense. No significant differences were found between reduced‐alcohol wines and their controls by triangle sensory tests using dark glasses for two of the three studied cultivars. Conclusion: The procedure described allowed production of wines with reduced alcohol content and pH, while retaining similar phenolic content and sensory properties. Significance of the Study: The proposed procedure is easy to apply, does not require specific equipment and offers a means of addressing the problem of wines developing high ethanol and low pH as a result of over‐ripening of grapes.     

不同发酵温度和浸渍时间对红葡萄酒理化指标的影响

本文研究了葡萄酒发酵过程中不同发酵温度和浸渍时间对葡萄酒理化指标的影响。温度控制在24～26℃,26～28℃,28～30℃;浸渍时间控制在5d,7d和10d。结果表明,当发酵温度在24～26℃时有利于葡萄酒酒精的转化和色素的浸出;在浸渍时间为7d时有利于对葡萄酒的色素和酚类物质的浸提。因此,发酵温度24～26℃为葡萄酒发酵最适温度;浸渍时间7d为葡萄酒最适浸渍时间。     

单一pH法、pH示差法和差减法央速测定干红葡萄酒中总花色苷含量的比较

为了寻求快速、经济地测定干红葡萄酒中总花色苷含量的方法,采用单－pH法、pH示差法和差减法对比分析3种方法测定数据的差异性。结果表明,3种方法测定的吸光度与浓度间均具有良好的线性关系,其相关系数R分别为0．9977、0．9988和0．9984,测定结果没有显著性差异（p〈0．05）。3种方法均能用于干红葡萄酒总花色苷含量的快速测定．     

Effects of fining with different bentonite labels and doses on colloidal stability and colour of a Valpolicella red wine

This study addressed four different labels of activated sodium bentonite during the fining of a young Valpolicella red wine. Preliminary tests determined the bentonite dose (0.15, 0.30 or 0.50 g L^?1) that would achieve colloidal stability, and this dose was further applied during laboratory‐scale trials. The bentonites were characterised by physico‐chemical parameters, and the effects of the label and dose on the wine colloidal stability, proteins, colour indices and phenolic compounds were measured. The results demonstrated that 0.50 g L^?1 for every bentonite label provided colloidal stabilisation without harshly affecting the colour. Unlike to what happens in white wines the least charged bentonite labels were effective at stabilising the red wine colloidal state by partially reducing its protein content. Simultaneously, the most negatively charged clay samples determined the largest depletions on the total polyphenols, anthocyanins, tannins and polymeric pigments. The differentiated action of clays with different surface charge density among white and red wines may be explained by the interaction mediated by positively charged anthocyanins towards either protein or tannin depletion. Although pioneering, these results may move towards the definition of a safe, allergen‐free, and effective adjuvant for colloidal stabilisation targeted to wine type.     

The effect of Saccharomyces cerevisiae and Saccharomyces bayanus yeast on colour properties and pigment profiles of a Cabernet Sauvignon red wine

Red wine was made from the same batch of Cabernet Sauvignon grapes but with two different yeasts, Saccharomyces cerevisiae (SC) or Saccharomyces bayanus (SB). The colour properties and pigment profiles of SC and SB wines were compared at 8 days and 387 days after yeast inoculation. Grape anthocyanin concentration was found to be lower in SB wines than in SC wines at day 8 and 387, but SB wine exhibited greater wine colour density, a* and b*. The anthocyanin concentration did not correlate with wine colour density. The levels of pigmented polymers and SO₂ non-bleachable pigments were found to be higher in SB wine at day 387, demonstrating that the formation of stable pyranoanthocyanins and pigmented polymers was enhanced by SB yeast. Electrospray mass spectrometry was used for the compositional analysis of pyranoanthocyanins, and direct and ethyl-bridged linked condensation dimers of malvidin 3- O -glucoside (MvG) with flavanols (catechin or epicatechin). The data demonstrated that the formation of acetaldehyde-mediated pigments was enhanced by the use of the SB yeast. The compositional analysis suggested that the differences in colour properties and pigment profiles of SC and SB wines were largely due to the greater production of acetaldehyde-mediated pigments by the use of SB yeast.     

Tuber components affecting acrylamide formation and colour in fried potato: variation by variety,year, storage temperature and storage time

Variation in asparagine and glucose contents, identified as precursors for acrylamide development in model experiments, has been studied in eight potato clones during long‐term storage at 3 and 10 °C. In addition, glutamine, fructose and sucrose contents were determined and the role of all five substances in colour formation in fried potato products was assessed. Large genotype differences were found in all characteristics, and the ranking order was almost the same for different years and storage times. Breeding for potatoes with low asparagine levels as well as low reducing sugar levels might be another way, in addition to altering processing parameters, to keep the acrylamide level low in fried products. Storage per se at low temperature did not result in higher asparagine levels. The risk that elevated reducing sugar levels during low‐temperature storage might lead to increased acrylamide levels needs further investigation. The determined tuber components accounted for only 11–60 per cent of the total variation in fry colour after storage at 3 °C. It is suggested that screening based on crisp colour in November, perhaps complemented with a few later controls on interesting clones, could be useful for sorting out clones with good crisping abilities during the rest of the low‐temperature storage season. Copyright © 2004 Society of Chemical Industry     

番茄粉中果胶含量粒径贮藏温度与色泽稳定性的相关性

以不同果胶含量、不同粒径的番茄粉为原料,研究贮藏温度对番茄粉色泽变化的影响。结果表明:番茄粉中果胶含量、粒径、贮藏温度与色泽的稳定性有一定的相关性。在不同温度条件下的整个贮藏过程中,低果胶含量的不同粒径番茄粉的L值、a值、b值均呈下降趋势,贮藏温度越高,下降幅度越大;高果胶含量的番茄粉在不同温度条件下的贮藏过程中L值均呈上升趋势,a值和b值由于贮藏温度不同呈现不同的变化趋势。     

不同贮藏温度及时间对3种菜肴中亚硝酸盐含量的影响

以芹菜、猪肉为原料,制成素炒芹菜（菜肴1）、炒肉丝（菜肴2）及芹菜肉丝（菜肴3）,分别测定3种菜肴炒制后在常温（25 ℃）贮藏和低温（4 ℃）贮藏过程中亚硝酸盐含量、pH值、菌落总数及感官品质的变化。结果表明,在25 ℃条件下,3种菜肴的亚硝酸盐含量均先迅速升高后显著降低,菌落总数快速增加,3种菜肴贮藏1 d已经变质;在4 ℃条件下,3种菜肴的亚硝酸盐保持较低数值且呈波动趋势,菌落总数在贮藏0～3 d增速缓慢,从感官品质判断,贮藏2 d之后3种菜肴均不可食用。试验表明温度对亚硝酸盐含量影响显著（P＜0.05）,低温可延缓微生物的生长进而抑制亚硝酸盐的生成,延长菜肴的保质期。     

Effect of storage on the phenolic content,volatile composition and colour of white wines from the varieties Zalema and Colombard

Different quality attributes and chemical components of wines change during storage as a function of a series of factors. Thus, in young white wines, changes in phenolics, that lead to modifications of their colour as a result of oxidation processes, are well-known. These reactions can also alter their volatile profile giving rise to the appearance of new aromas, which in some cases are undesirable. In this study we have carried out a thorough evaluation of the changes in the colour, volatiles and phenolics of Zalema and Colombard wines during 1 year of storage under different conditions of temperature and position. The phenolics and colour were more affected than was the volatiles profile and wines kept in the cold could be clearly distinguished from the others, whilst the position of the bottles onlt slightly affected the wines during storage. Results showed that the blending of Zalema wines with Colombard wines may be an appropriate means of enhancing the acidity of the former without dramatically affecting its character.     

储存温度及时间对三文鱼中组胺和色胺

目的 探讨生物胺作为这种海洋食品鲜度变化参考指标的可行性。方法 采用柱前衍生-高压液相色谱法检测三文鱼在不同储存温度及时间下生物胺含量的变化。结果 分别在?18 ℃、4 ℃和10 ℃的冰箱中保存的样品, 于0 h、12 h、36 h、48 h后均可检测到色胺和组胺, 储存后的三文鱼中组胺含量较高, 含量随温度、时间的增加而增加; 在4 ℃下, 三文鱼中组胺的生成与时间呈现一定的线性关系。结论 在该温度下, 组胺可作为三文鱼肉新鲜程度的质量指标。     

Effects of storage temperature and time on the biogenic amine content and microflora in Korean turbid rice wine,Makgeolli

We examined biogenic amine (BA) content and the diversity of lactic acid bacteria (LAB) population in Korean rice wine, Makgeolli, stored at 4 and 20 °C. Among 8 BAs examined by HPLC, only putrescine was detected in low levels during 30 days of storage at 4 °C. However, at 20 °C, several BAs were detected and total BA concentration increased during storage. The numbers of LAB in 4 °C Makgeolli remained constant while those in 20 °C Makgeolli were markedly changed. Denaturing gradient gel electrophoresis (DGGE) analysis shows the major LAB population in 4 °C Makgeolli to be Pediococcus acidilactici while that in 20 °C Makgeolli to be Lactobacillus plantarum, which has been known to produce BAs. The present study suggests that if Makgeolli is stored at an improper temperature, the diversity of LAB populations and BA formation can be markedly increased. Thus, low temperature storage and transport of the products are required to maintain a BA-free state.     

贮藏温度和时间对鳝鱼肌肉鲜度及生物胺 含量的影响

目的 为生鲜调理型鳝鱼制品的生产及安全控制提供保障。方法 以黄鳝为对象,测定在不同温度下(-0.5、4、15、30℃)黄鳝肌肉的菌落总数、氨基态氮、TBA、TVB-N、K值和生物胺含量及其在贮藏过程中的变化,研究了贮藏温度和时间对鳝鱼肌肉鲜度和生物胺含量的影响。结果 在-0.5、4、15、30℃4种温度贮藏时,贮藏温度越高,鳝鱼肌肉中菌落总数、K值、TVB-N以及氨基态氮含量增加速度越快,鳝鱼肌肉的鲜度下降越快。新鲜鳝鱼肌肉K值小于10%,在4、15、30℃下贮藏鳝鱼肌肉K值分别在第8 d、第4 d、12 h就超过了60%,而在-0.5℃贮藏14 d鳝鱼肌肉的K值都能保持在55%以下。生物胺的产生与贮藏温度和时间有着密切的联系,温度越高,时间越长,总生物胺产生量越高,腐胺和尸胺变化最为显著。在-0.5、4、15、30℃下贮藏鳝鱼肌肉生物胺含量分别在第14 d、第10 d、第4 d、第12 h超过20 mg/100 g。结论 鳝鱼肌肉应在-0.5℃贮藏,可以有效保持鲜度和控制脂肪氧化,减少微生物生长和生物胺产生,延长货架期。     

The impact of closures, including screw cap with three different headspace volumes, on the composition, colour and sensory properties of a Cabernet Sauvignon wine during two years' storage

This paper presents the results from an investigation to assess the development of a Cabernet Sauvignon wine bottled with different closures including a screw cap (ROTE, roll-on-tamper-evident) and different ullage volumes (4, 16 and 64 mL of air). The wines were filled manually, sealed using commercial equipment and stored under controlled temperature and humidity conditions. The concentration of free and total SO₂, and phenolic compounds including anthocyanins, selected pigments, pigmented polymers and tannins, and colour measurements using spectral and CIELAB methods, have been determined in the wines over a two-year storage period. In addition, sensory analysis of the aroma and palate properties of the wines was performed after 6, 9, 11, 18 and 24 months' storage. The wines sealed under the screw cap with either 4 or 64 mL ullage volumes were clearly different from each other and the other treatments in the study, and these differences were seen within the first year after bottling. The wines bottled under the more commercially relevant conditions, screw cap with 16 mL headspace, synthetic closure or natural bark closure, were more similar in both composition and sensory characters, although subtle differences between different closures were evident. 'Rubbery' and 'struck flint' like aromas (generically termed reduced aroma) were detected in some of the wines in the study but were not a large or dominating character. The scores for this character were highest in the wine sealed under the screw cap with the smallest ullage volume.     

Coupling effects of preheating time and extraction medium pH on red radish anthocyanin yield,glucosinolate degradation and off‐odour removal

In this study, the effect of combined preheating time (2, 5, and 10 min) and extraction medium pH (2.5, 3.5, and 4.5) on total monomeric anthocyanin yield, and removal of off‐odour in red radish anthocyanins were evaluated. The tentative anthocyanin identification showed twelve pelargonidin anthocyanins, and only nine were identified in samples preheated for 10 min. Sample preheated for 10 min and extracted at pH 4.5 showed lower the anthocyanin yield (98.02 mg/100 g, FW), lighter colour and higher percentage polymeric colour compared with that preheated for 2 min and extracted at pH 2.5. However, prolonged preheating time (10 min) significantly reduced myrosinase enzyme activity by 73%. Additionally, results showed that preheating time and extraction medium pH have negative and significant effect on the total monomeric anthocyanin yield, while they showed positive and negative significant effect on the total glucosinolate degradation. Furthermore, the sensory evaluation results revealed no significant difference in radish odour for samples preheated for 2 and 5 min followed by anthocyanin extraction in pH 2.5 medium. It might therefore be concluded that the combination of moderated preheating treatment time (≤5 min) and lower extraction medium pH could be effective to reduce the off‐odour characteristics and maintaining high yield and stable red radish pigment.     

Study on the influence of temperature,storage time and packaging type on di-n-butylphthalate and di(2-ethylhexyl)phthalate release into packed meals

Ready-to-eat meals packed in polyethylene terephthalate (PET) and aluminium dishes, supplied to patients in two hospitals in the Campania region (Italy), were studied to evaluate the probable migration of di-n-butylphthalate (DBP) and di(2-ethylhexyl)phthalate (DEHP) from the packaging into the food. The influence of temperature, storage time and type of package on the migration process was considered, analysing the meals according to three time ranges, before the packaging (T ₀) and after 60?min (T ₁) and 120?min (T ₂) from packaging during the storage in thermostatic delivery carts. At T ₀ in the meals sampled before packaging in PET dishes, mean levels of DBP and DEHP were 0.023?±?0.002?µg/g and 0.069?±?0.041?µg/g, respectively; the DBP level increased 230% and that of DEHP increased 208% by time T ₀ versus T ₂. In the meals sampled before packaging (T ₀) in aluminium dishes, the mean levels of DBP and DEHP were 0.030?±?0.001?µg/g and 0.057?±?0.015?µg/g, respectively. The significant increase in contaminant levels over storage times for meals packed in PET dishes demonstrates that from packages made of plastic materials the migration of phthalic acid esters into foods is possible. In meals packed in PET dishes, the highest DBP and DEHP increases were observed in the T ₀ to T ₁ range, which represented the time interval over which meals were kept hot, and mainly in the first ones, where the highest temperatures have been recorded.     

干燥方式、储存温度和品种对玉米中伏马毒素B1的影响

伏马毒素B_1广泛存在于玉米中,是玉米及其制品质量安全的重要危害因子。选取23个玉米品种为研究对象,对不同干燥方式(烘干、晒干和晾干)和不同储藏温度(4、15、25℃、常温)对其中伏马毒素B_1的影响进行研究,结果表明:玉米进行烘干、晒干和晾干后放置3个月后,伏马毒素B_1含量为烘干晒干晾干,玉米水分含量与伏马毒素B_1含量显著相关(r=0.678);不同温度中放置3个月后,伏马毒素B_1含量由小到大为4℃15℃25℃室温;烘干、4℃储存玉米中伏马毒素B_1含量分别为0～1.39 mg/kg(平均值0.40 mg/kg)、0.08～1.60 mg/kg(平均值0.78 mg/kg),均低于美国FDA规定的最高限量(2 mg/kg);品种对玉米中伏马毒素B_1含量影响显著。烘干、4℃储存、选取高抗镰刀菌玉米品种可有效控制在储藏过程中伏马毒素B_1对玉米的污染。