Nonenzymic browning reactions in boiled grape juice and its models during storage

Reaction orders, rate constants and activation energies were evaluated for 5-hydroxymethyl furfural (HMF) accumulation and brown pigment formation (BPF) in pekmez and its model systems stored at 55, 65 and 75°C over 10 days at pH 4.0. The model systems and their compositions were decided by considering the major pekmez components. Accumulation of HMF and BPF were the highest in pekmez and they were the smallest in model 1. ANOVA showed that the effects of temperature on both accumulation of HMF and BPF were significant (p<0.05). Results obtained from non-linear regression analysis indicated that reaction order was 0.5 for 5-HMF accumulation and was zero for brown pigment formation in the model systems. Reaction orders were zero for both HMF accumulation and BPF in pekmez. Calculated activation energies for HMF and brown pigment formation were in the range of 49.7–103 kJ mol⁻¹ and 116–132 kJ mol⁻¹ respectively.     

New beverages of lemon juice with elderberry and grape concentrates as a source of bioactive compounds

Considering the health potential of lemon and berry fruits, different functional beverages rich in antioxidant phytochemicals, which demonstrated beneficial effects, were developed. To fulfill this objective, lemon juice was combined with 2 different concentrates, elderberry and grape, in a proportion of 5% (w/v). Bioactive composition (flavonoids and vitamin C) and color stability, as well as the antioxidant capacity of mixtures, during a period of 56 d of storage, were studied. A protective role of anthocyanins on ascorbic acid preservation was noted for both lemon-berry blends, keeping vitamin C stable until the end of the storage. In addition, the new drink combining lemon and elderberry performed better than the grape-lemon mixture in terms of health-promoting phytochemicals content, just as in vitro antioxidant capacity and color characteristics. PRACTICAL APPLICATION: Beverages made from lemon juice and berries could contribute to develop new drinks with a prolonged preservation of bioactive compounds throughout storage, keeping an attractive color and a high antioxidant activity during long periods of time. The information obtained in the present work is in agreement to the rules of health and safety for juices established by the Directive of European Commission Dir2001/112/CE incorporated to the Spanish law through the RD1050/2003 regulation. Consequently, an improved performance of industrial products would be achieved.     

慕萨莱思熬煮液流变学特性分析

对不同浓度的慕萨莱思熬煮液流变学特性在不同温度下的流变学特性进行研究。结果显示,在15⁵5℃,10²5°Brix范围内,慕萨莱思熬煮液为牛顿性流体,其变化符合粘度受温度影响的阿累尼乌斯方程和受浓度影响的指数方程,受两者综合影响为η=3.3×10-7e19914e0.0056C/RT。上述结果为慕萨莱思加工工艺设计提供理论基础。      

Volatile compounds of blackcurrant juice and wine

Volatile compounds of blackcurrant juice, concentrate and wine were analysed by applying a dynamic headspace gaschromatographic method based on selective capillary column trapping. A significant sensorial difference between the wine made from blackcurrant juice and that from concentrate was found by duo-trio assessment for aroma, while only a slight difference was observed in the volatile composition of the wines. Blackcurrant wines contained only a few terpene compounds, whereas numerous terpenes were identified from the juice. Differences between the blackcurrant juice and concentrate were found, with some terpene compounds appearing in higher amounts in the former.

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Flüchtige Verbindungen im Saft und im Wein der Schwarzen Johannisbeere

Zusammenfassung Flüchtige Verbindungen von Saft, Konzentrat und Wein der Schwarzen Johannisbeere wurden mittels der dynamischen Kopfraum-gaschromatographischen Methode untersucht, wobei die flüchtigen Substanzen selektiv mit einer Capillarsäule erfaßt wurden. Es konnten bei der Duo-trio-Bestimmung des Aromas signifikante sensorische Unterschiede zwischen dem Wein aus Saft und dem Wein aus Konzentrat festgestellt werden, während ein nur geringer Unterschied bei der Zusammensetzung der flüchtigen Verbindungen der Weine zu beobachten war. Die Weine aus der Schwarzen Johannisbeere enthalten nur wenige terpene Verbindungen, bei Saft dagegen konnte eine größere Anzahl an Terpenen nachgewiesen werden. Bei dem Vergleich von Saft und Konzentrat zeigte sich ein höherer Anteil an terpenen Verbindungen im Saft.

     

Gas chromatographic determination of diethylene glycol in wine, grape juice and grape-juice concentrates

A gas chromatographic method for the quantitative determination of diethylene glycol in wine, red and white grape juice, and red and white grape juice concentrates is described. The method includes continuous extraction of the diethylene glycol with ethyl acetate by the aid of a rotation perforator. Using the new generation of chemically bonded stationary phases on fused silica together with an appropriate modern cold on-column injection system coupled with an autoanalyzer and a retention gap, the GLC analysis is shown to provide adequate information for quality control purposes. Linearity, precision and recovery with the described procedure were investigated. The precision of the method was studied using a sample containing approximately 65 mg/l diethylene glycol. Twelve separate determinations were performed by the described method; the coefficient of variation was 3.9%. The detection limit of our method is 5 mg/l diethylene glycol both for wine, grape juice and grape juice concentrates. Recovery data are based on wine, grape juice and grape juice concentrates fortified with diethylene glycol at different levels. The ranges of concentration used in this study were 10 mg/l to 10 g/l for wine and 10 mg/l to 100 mg/l for grape juice and grape juice concentrate. The average recovery of diethylene glycol for wine at all concentrations tested was 98.8%; coefficients of variation were between 1.6 and 8.0%. Recoveries of diethylene glycol added to grape juice at the level of 10 mg/l to 100 mg/l were 96% to 109%.     

Physicochemical parameters,bioactive compounds and microbial quality of sonicated pear juice

This study was carried out to investigate the effect of sonication on physicochemical parameters and microorganisms of pear juice. Ultrasound processing of fresh pear juice was done at fixed amplitude [70% (500 W) and frequency (25 kHz) for 0, 15, 30, 45 and 60 min at 25 °C. Total soluble solids, pH, titratable acidity and Ca and Mn remained stable, while the cloud value, ascorbic acid, total phenols, total flavonoids, total antioxidant capacity, sugar contents and Na, K, Fe and Mg showed a significant increase. Decreases in microbial population and P and Cu were also observed. It may be inferred that ultrasound processing for 60 min exhibited optimum results in terms of physicochemical and microbial quality.     

Ochratoxin A in wine and grape juice sold in Canada.

Ochratoxin A (OTA) was determined in 251 samples of wines and grape juice collected over 3 years in Canada. In total, 25/84 samples of red wine, 22/96 samples of white wine, 3/46 red grape juices and 1/25 white grape juices contained OTA levels above the limit of quantitation (LOQ). Canadian wines, when compared with imported products, showed both a lower OTA occurrence, noted as positive (19 versus 48% above the limit of detection (LOD) for wines), and a lower level of OTA contamination (upper bound mean of 17.5 versus 163pg ml(-1) for wines). Wines from the USA contained no quantifiable levels of ochratoxin A. OTA was found in Canadian and US grape juice samples, with 12.9% above the LOD and an upper bound mean of 13.3pg ml(-1). It was extracted from a wine or grape juice sample by passing it through an immunoaffinity column. The sample matrix was washed off the column with water. OTA was eluted from the column with methanol and quantitatively determined by liquid chromatography using a fluorescence detector. The presence of OTA was confirmed by esterification with boron trifluoride-methanol. The LOQ of OTA was estimated as 20 pg ml(-1) in white wine (S/N 10:1) and 40 pg ml(-1) in red wine, white grape juice and red grape juice (S/N 20.1). The LOD was estimated as 4pgml(-1) for white wine and 8pgml(-1) for red wine and white and red grape juices (S/N 3:1).     

葡萄梗(茎)中的生物活性物质研究现状

葡萄梗(茎)是葡萄加工业副产物之一,富含高附加值的生物活性成分,可用于食品、医药和化妆品等工业领域,但较少被人们关注和开发。本文介绍了葡萄梗(茎)中生物活性物质的分布和分离纯化的研究现状,旨在为葡萄生产废弃物葡萄梗(茎)的综合利用提供一定的参考和借鉴。      

Detection of ochratoxin A in tropical wine and grape juice from Brazil

BACKGROUND: Ochratoxin A (OTA) is the main mycotoxin found in grapes, wines and grape juices and is considered one of the most harmful contaminants to human health. In this study, samples of tropical wines and grape juices from different grape varieties grown in Brazil were analysed for their OTA content by high‐performance liquid chromatography. RESULTS: The detection and quantification limits for OTA were 0.01 and 0.03 µg L^?1 respectively. OTA was detected in 13 (38.24%) of the samples analysed, with concentrations ranging from < 0.03 to 0.62 µg L^?1. OTA was not detected in any of the grape juice samples. Most of the red wine samples proved to be contaminated with OTA (75%), while only one white wine sample was contaminated. However, the OTA levels detected in all samples were well below the maximum tolerable limit (2 µg L^?1) in wine and grape juice established by the European Community and Brazilian legislature. CONCLUSION: The results of this study indicate a low risk of exposure to OTA by consumption of tropical wines and grape juices from Brazil. © 2012 Society of Chemical Industry     

The metabolic fate of red wine and grape juice polyphenols in humans assessed by metabolomics

The metabolic impact of polyphenol‐rich red wine and grape juice consumption in humans was studied using a metabolomics approach. Fifty‐eight men and women participated in a placebo‐controlled, double‐crossover study in which they consumed during a period of 4 wk, either a polyphenol‐rich 2:1 dry mix of red wine and red grape juice extracts (MIX) or only a grape juice extract (GJX). Twenty‐four‐hour urine samples were collected after each intervention. ¹H NMR spectroscopy was applied for global metabolite profiling, while GC‐MS was used for focused profiling of urinary phenolic acids. Urine metabolic profiles after intake of both polyphenol‐rich extracts were significantly differentiated from placebo using multilevel partial least squares discriminant analysis. A significant 35% increase in hippuric acid excretion (p<0.001) in urine was measured after the MIX consumption as) or only a red grape juice dry extract (GJX). 24‐h urine samples were collected after each intervention. 1H‐NMR spectroscopy was applied for global metabolite profiling, while gas chromatography‐mass spectrometry (GC‐MS) was used for focused profiling of urinary phenolic acids. Urine metabolic profiles after intake of both polyphenol‐rich extracts were significantly differentiated from placebo using multilevel partial least squares discriminant analysis (ML‐PLS‐DA). A significant 35% increase in hippuric acid excretion (p<0.001) in urine was measured after the MIX consumption compared with placebo, whereas no change was found after GJX consumption. GC‐MS‐based metabolomics of urine allowed identification of 18 different phenolic acids, which were significantly elevated following intake of either extract. Syringic acid, 3‐ and 4‐hydroxyhippuric acid and 4‐hydroxymandelic acid were the strongest urinary markers for both extracts. MIX and GJX consumption had a slightly different effect on the excreted phenolic acid profile and on endogenous metabolite excretion, possibly reflecting their different polyphenol composition.     

Effect of thermosonication on bioactive compounds in watermelon juice

Freshly squeezed watermelon juice was subjected to thermosonication treatments with processing variables of temperature (25-45 °C), amplitude level (24.1-60 ??m) and processing time (2-10 min) at a constant frequency of 20 kHz and pulse durations of 5 s on and 5 s off. Hunter color values (L*, a* and b*), lycopene (LC), phenolic content (TP) and ascorbic acid (AA) content were measured. Higher retention of AA and LC was observed at low treatment conditions. AA, LC & TP decreased significantly at higher amplitude levels and at the maximum processing time. A second order response function covering the range of experimental conditions investigated was obtained for each of the compounds measured. Model predictions for color parameters and bioactive compounds were closely correlated to the experimental results obtained. Prediction models were found to be significant (p < 0.05) with low standard errors and high coefficients of determination (R²). It was concluded that thermosonication significantly influences key watermelon juice quality parameters     

Recovery of bioactive compounds in kiwifruit juice by ultrafiltration

Food quality is not only a function of nutritional values but also of the presence of bioactive compounds exerting a positive effects on human health.This research was undertaken to study the influence of the ultrafiltration (UF) on the composition of some bioactive compounds of the kiwifruit juice in order to develop a natural product which can be used to fortify foods and beverages. At the same time the effect of transmembrane pressure (TMP) and temperature on the permeate flux was also investigated in order to identify the optimal operating conditions for the processing of the juice. An optimal TMP value occurred at 0.6–0.65 bar in different conditions of cross flow velocities. Steady-state permeate fluxes increased linearly with temperature in the range 20–30 °C.The kiwifruit juice was clarified in optimal operating conditions, according to the batch concentration mode, up to a final volume reduction factor (VRF) of 2.76.The analyses of flux decay according to fouling models reported in the literature revealed that the formation of a cake layer covering the entire surface of the membrane is the main cause of the membrane fouling.Most bioactive compounds of the depectinised kiwifruit juice were recovered in the clarified fraction of the UF process. The rejection of the UF membrane towards total phenolics was 13.5%. The recovery of glutamic, folic, ascorbic and citric acids, in the clarified juice, with respect to the initial feed, was dependent on the final VRF of the UF process: an increase of the VRF determines an increase of these compounds in the clarified juice. The rejections of the UF membrane towards these compounds were in the range 0–4.3%.

Industrial relevance

Among different substances contained in the kiwifruit a primary role, in the safeguard of the human health, is carried out by some bioactive compounds such as ascorbic, folic, citric, glutamic acids and polyphenols.This research was undertaken to study the influence of ultrafiltration on the composition of these compounds in order to develop a natural product which can be used to fortify foods and beverages.     

Mousy off-flavour production in grape juice and wine by Dekkera and Brettanomyces yeasts

The ability of four known species of Dekkera and Brettanomyces yeasts to produce mousy off-flavour in grape juice and wine was investigated for the first time. Using a sensory assessment technique the twelve type strains of Dekkera and Brettanomyces , representing four species, were found to grow and to be capable of producing mousy off-flavour in a grape juice medium; however, differences between strains were apparent. Four strains representing the two species of Dekkera (D. bruxellensis and D. anomala ) known to be associated with the spoilage of wine and other fermented beverages were further investigated for mousy off-flavour production in a red and white wine supplemented with nutrients. D. anomala and only one of the three D. bruxellensis strains tested grew in both wines and generally produced a moderate level of off-flavour, whereas the remaining two strains of D. bruxellensis , despite slowly losing viability (10- to 100-fold) over the 52–55 day period, produced detectable off-flavour. This work demonstrates the general ability of Dekkera and Brettanomyces yeasts to produce mousy off-flavour and confirms the importance of these yeasts for off-flavour production in grape juice and wine.     

桑葚果酒发酵过程中功能性物质的检测及其变化情况

桑葚是一种药食两用水果,既鲜美可口,又含有大量功能性物质。笔者在前期通过菌种选育和发酵条件优化,得到了口感良好的桑葚果酒。为了分析桑葚果酒发酵过程中的功能性物质,及其抗氧化能力的变化情况,依据桑葚特点,首先优化了测定总花色苷含量的pH值示差法,并确定了桑葚果酒中花色苷单体主要是矢车菊素-3-葡萄糖苷和矢车菊素-3-芸香糖苷。在此基础上,测定并比较了桑葚果酒与市售桑葚果酒的功能性物质含量及DPPH清除率,发现酿造桑葚果酒的功能性物质含量和抗氧化能力远优于市售果酒。对桑葚果酒发酵过程和储存过程中的功能性物质含量和抗氧化能力进行了跟踪分析,结果发现桑葚果酒发酵过程中功能性物质含量和DPPH清除率均有一定下降,而其在储藏过程中能够稳定存在。     

Influence of packaging material on pomegranate juice colour and bioactive compounds,during storage

Pomegranate juices were assessed after pasteurisation and storage in different packaging materials: transparent and green glass, and paperboard carton with polyethylene layers (Minibrik‐200). The main objective was to establish the influence of the container on the stability of colour and bioactive compounds (anthocyanins, ellagic acid and other non‐coloured phenols). Results showed that non‐coloured phenols and ellagic acid were quite stable during the storage period. In contrast, anthocyanins degraded, to an extent directly proportional to colour loss, less for those juices stored in glass bottles than for those stored in Minibrik. These results indicated that these paperboard carton containers are oxygen permeable, and that oxygen has a greater influence on anthocyanin, and consequently on colour degradation, than light on pomegranate juice during storage. Nevertheless, the antioxidant activity was not influenced by the packaging material employed. Copyright © 2004 Society of Chemical Industry     

Antioxidant activities of organic grape, pomace, juice, must, wine and their correlation with phenolic content

The highest values of antioxidant activity (AOA), inhibition of low‐density lipoproteins (LDL‐diene, LDL‐MDA) and total phenols were determined in pomace (82.30 and 82.60%), grapes (68.91%) and must [2750 mg L^?1 gallic acid equivalents (GAE)], respectively. For all parameters (AOA, iLDL‐diene, iLDL‐MDA, total phenols) the highest values were obtained in Cabernet Sauvignon and Merlot grape varieties. Positive correlations were determined between AOA and iLDL‐diene (r = 0.809); AOA and total phenols (r = 0.528); total phenols and iLDL‐diene (r = 0.451) with significance of P < 0.005. The results of principal component analysis demonstrated that the location of iLDL‐diene and AOA is the same for pomace, must and red wines. The total phenols are found in the same place in red wines, red grapes, pomace and must. The results emphasize the importance of must, pomace and red wine for inhibiting LDL‐oxidation.     

葡萄与葡萄酒中的白藜芦醇

前 言白藜芦醇（Resveratrol，简称Res），化学名称为3,4′,5－三羟基1,2－二苯基乙烯（3,4′,5－Trihydroxysilbene）具有顺式与反式两种结构，是一种酚类化合物。经研究表明白藜芦醇具有一定的保健功能，特别对心血管疾病很有效，是目前世界关注的一个热点，它具有以下特点：（1）抗氧化、抗自由基作用；（2）对心血管疾病的防治作用。目前人们已在多种植物中发现有白藜芦醇，如花生、桑椹、虎仗、葡萄等，葡萄酒中含有一定量的白藜芦醇，尤其在红葡萄酒中含量较高，也就是造成法国人“PARADOX”的原因。由于白藜芦醇含量很少，不能…     

Evaluation of the bioactive compounds and the antioxidant capacity of grape pomace

Grape pomace is an agro‐industrial residue produced worldwide and mainly employed for animal feed or as a fertiliser. Several studies have shown that grape pomace is a rich source of bioactive compounds, such as phenolic compounds, polysaccharides, fatty acids and others. Three varieties of grape pomace were evaluated in this study. Antioxidant activity was determined by three different methods, namely, DPPH˙, ABTS and ferrous ion assays. Fatty acids and phenolic compounds were identified, respectively, by gas and liquid chromatography. Results showed that grape pomace is a rich source of polyunsaturated fatty acids and phenolic compounds. Cabernet Sauvignon pomace revealed higher values of total phenolic compounds, total flavonoids and total monomeric anthocyanin, and presented the lowest value of EC₅₀, and thus a higher antioxidant activity among the samples analysed.     

Occurrence of ochratoxin A in wine and grape juice marketed in Rio de Janeiro, Brazil.

Ochratoxin A (OA) is receiving attention world-wide because of the hazard it poses to human health. The aim was to test the distribution of OA in grape juice, pulps of frozen grapes, and national and imported table wine obtained from markets in Rio de Janeiro, Brazil. Analytical methodology using immunoaffinity column for OA extraction and clean-up with a final separation on a reversed-phase (C(18)) column and fluorescence detection in high-performance liquid chromatography showed a detection limit of 21 ng l(-1). The mean recovery was 91% for red wines and 82% for white wines; while the mean recoveries for juices and pulps of frozen grapes were 91.6 and 88%, respectively. Of 64 samples of grape juice and frozen pulps, 25% were positive for OA, being the mean content of 37 ng l(-1) with a maximum concentration of 100 ng l(-1). In wines, the mean concentration detected in 80 samples analysed was 34.4 ng l(-1) with 28.75% of positive samples. Red wines showed the highest percentages and levels of contaminated samples: 38% and 37 ng l(-1), respectively. The white wine contained levels above 26 ng l(-1) in 17.75% of the analysed samples. The levels of contamination detected in red wine sold in Río de Janeiro were not enough to surpass the virtually safe dose established as 5 n g kg(-1) body weight of daily intake.