Free amino acids and volatile compounds in vinegars obtained from different types of substrate

The present work reports on the free amino acids and volatile compounds in vinegars obtained from different types of raw materials (cider, white wine and red wine). Based on the amino acid contents of three types of vinegar and of the substrates from which they were obtained, the profile of the nitrogen‐supplying compounds and their uptake for the acetic acid bacteria were very similar. The most important amino acid in terms of supply and uptake was found to be L ‐leucine. L ‐Proline proved also important in the wine vinegars, however it was not depleted as L ‐leucine. The different acetification reactions involved were found to yield acetoin, and plus 1,1‐diethoxyethane in the wine vinegars. Copyright © 2004 Society of Chemical Industry     

Trace metals and flavonoids in different types of tea

The mineral and flavonoid contents of commercially available different types of teas (premium black, flavored black, green, and fruit tea) and the infusions produced from them were determined. Studied teas differed in the contents of elements between their raw materials and infusions. Iron and copper exhibited the lowest efficiency of extraction by hot water. For the most popular black tea brand (Lipton® Yellow label) the efficiency of metal extraction decreased in the order: Co>Mn>Ni>Zn>Cu>Fe. Flavored black Citrus tea infusion had the highest content of Co and Ni, while Yellow label and Green Indonesia are a good source of Fe, Mn, and Zn. Flavonoids were predominantly present as glycosides. Rutin was present at much higher levels in black and green teas. Significant amounts of naringin and hesperidin were determined in tea infusions with citrus aromas or fruits.     

固相微萃取-气相色谱测定醋中的挥发性成分

采用顶空固相微萃取-气相色谱法对酿造食醋和配制食醋的挥发性成分进行了定性定量分析研究,发现不同醋样所含的挥发成分的种类及其含量均存在着较大的差异性,为评价和鉴定食醋的内在质量建立了一个准确的方法。     

Characterisation of white vinegars of different sources with artificial neural networks

Wine and cider vinegars currently attract growing interest from consumers, giving rise to a consequent increase in supply. A full appreciation of their quality is only possible, however, through recognition of their superior quality when compared with vinegars produced from raw materials of inferior quality. Therefore, it is necessary to pinpoint the parameters that define the quality of these products. Chemico-physical and sensory analysis has been used to draw up artificial neural networks (ANNs), on the basis of a vast sampling of vinegars from various countries, produced from a variety of raw materials, that was already subjected to multivariate statistical analysis. Among the chemical parameters, polyalcohols and other elements such as pH, tartaric acid and proline proved to be highly reliable, whereas other volatile substances and the results of sensory analysis were not very discriminating and could not be used to re-classify samples of unknown origin. The positive results obtained indicate that ANNs are a powerful mathematical tool, since they can be used to construct models that predict the botanical origin of the product and to re-classify samples of unknown origin, without any initial restrictive hypothesis. © 1998 Society of Chemical Industry.     

基于主成分分析法的不同甘薯醋品质评价

为评价5种甘薯醋的综合品质,对不同甘薯醋的p H、总可溶性固形物(total soluble solid,TSS)、总糖、总酸、总多酚、总酯、L*值、a*值、b*值、DPPH自由基清除率和ORAC值11个品质指标进行测定,并对其进行主成分分析。不同甘薯醋间p H、TSS、总酯和亮度值L*、红绿值a*、黄蓝值b*值存在显著性差异,渝紫7号与13-3-35的彩度值C*、总酚及抗氧化能力无显著性差异,而与其他醋差异显著。通过主成分分析将11个品质指标简化为2个主成分,主要反映营养成分、颜色和抗氧化能力信息。5种甘薯醋综合品质得分从高到低为13-3-35>渝紫7号>渝15>渝19>渝27。本文筛选出可用于判断甘薯醋品质的6个指标,包括总酸、总酯、a*值、b*值、DPPH和ORAC值,为甘薯醋品质简易判断提供了一种方法。     

Metallic contaminants in Andalusian vinegars

A study on the content of several metallic ions and arsenic in Andalusian vinegars has been carried out. The technique employed was atomic absorption spectrophotometry. The measurements were performed directly in the samples. The determination of these ions is interesting since they can produce in certain amounts undesirable organoleptic effects or even make an attempt on the health (toxic elements). No kind of relevant contamination was found.     

Antioxidant activity and phenolic content of wine vinegars produced by two different techniques

BACKGROUND: The presence of phenolics in fruit, red wine and vinegar has positive health effects due to their significant antioxidant activity. The aim of the study was to determine the effects of two different vinegar production methods on antioxidant activity and phenolic level of vinegars derived from Ulugbey Karasi grapes. Traditional surface and industrial submerge methods were used to make vinegar. Samples were taken from fresh red grape juice, maceration, wine, traditional vinegar and industrial vinegar. RESULTS: Total phenolic content of traditional and industrial vinegar samples were 2690 mg L^?1 and 2461 mg L^?1 GAE, respectively. ORAC values of traditional and industrial vinegar samples were 10.50 µmol mL^?1and 8.84 µmol mL^?1 TE, respectively. Antioxidant activity values of traditional and industrial vinegars were 13.50 mmol L^?1 and 10.37 mmol L^?1 TEAC, respectively. Gallic acid, catechin, epicatechin, chlorogenic acid, caffeic acid, syringic acid, p‐coumaric acid and ferulic acid were detected in grape juice, wine and vinegar samples. The content of catechin in industrial vinegar (27.50 mg L^?1) was significantly higher than that of in traditional vinegar (13.76 mg L^?1) (P < 0.05). Traditional vinegar had higher amounts of chlorogenic and syringic acids than the industrial vinegar (P > 0.05). CONCLUSION: Results of this study showed that different production methods affected the functional constituents of wine vinegars. Copyright © 2010 Society of Chemical Industry     

Volatile compounds in red wine vinegars obtained by submerged and surface acetification in different woods

Changes in volatile components were investigated during controlled acetifications. The substrates used to perform traditional surface acetifications were two red wines. Barrels of four different woods (oak, chestnut, acacia and cherry) were used. Submerged acetifications were performed at the laboratory scale. Volatile compounds were analysed by Headspace Sorptive Extraction and Gas Chromatography–Mass Spectrometry (HSSE-TD–GC–MS). Out of 57 compounds identified in the samples, 38 were quantified. Of these, ethyl furoate, ethyl benzoate and limonene had never been described in wine vinegars. Acetifications led to an increase in the total quantity of volatile components, which were higher in the surface processes. Acetic esters were predominant in surface culture vinegars, whereas acids were predominant in submerged culture vinegars. Oak-lactones were quantified only in vinegars produced in oak barrels. Ethyl furoate and ethyl benzoate increased in cherry wood barrels. Multivariate statistical analysis supported the influence of the process on the volatile composition of the final vinegars.     

Evaluation of antioxidant activity and total phenols index in persimmon vinegars produced by different processes

The total phenols index (TPI) and antioxidant activity of persimmon vinegars produced by different processes were evaluated. A novel extraction method was designed and optimised for this purpose with respect to the type and concentration of solvent and ultrasonication time. The best extraction conditions found were the use of 80% ethanol and 25 min of ultrasonication. Antioxidant capacity was determined by the oxygen-radical absorbance capacity of fluorescein (ORAC-FL) and 2,2′-diphenyl-1-pycrylhydrazyl (DPPH) free-radical assays. The antioxidant activities were the same in the fruit and the vinegar, except in the ORAC assay, which showed a significant decrease during the acetification process. The results showed that using the wild yeast strain native to the persimmon produced vinegars with higher antioxidant activity than that of an inoculated alcoholic fermentation. Finally, a comparison between our vinegars and other commercial examples was made. The TPI and antioxidant activity values of persimmon vinegars were always higher than those obtained from white and red-wine vinegars. The antioxidant activity and total phenols of the final product indicate that persimmon vinegar is a competitive product in the market.     

Volatile components in Andalusian vinegars

Summary The volatile fraction of different wine vinegars from Andalusia was studied, using gas chromatography. The identification of the peaks was based on the internal standard method. An outstanding content of volatile components was observed. High amounts were obtained for ethyl and methyl acetate as well as for isoamyl alcohols, which are the characteristic products of the acetification process. Relevant values were found for methanol and in some cases they exceeded those stipulated in the Spanish regulations.

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Flüchtige Verbindungen in andalusischen Weinessigen

Zusammenfassung Es wurde eine Studie über die flüchtige Fraktion verschiedener Weinessige aus Andalusien unternommen. Hierbei wurde die Gaschromatographie angewendet. Die Identifizierung der Peaks gründete sich auf internationale Standardmethoden. Ein hervorstechender Gehalt an flüchtigen Bestandteilen wurde allgemein beobachtet. Als charakteristische Produkte der Essigherstellung wurden größe-re Mengen an Ethyl- und Methylacetat und an Isoamylalkohol erhalten. Bedeutungsvolle Werte wurden für Methanol gefunden, die in einigen Fällen über die spanischen Vorschriften hinausgingen.

     

Changes of volatile compounds in wine vinegars during their elaboration in barrels made from different woods

Changes in the volatile components of red wine vinegars and balsamic vinegars were investigated during 1 year of aging in wood barrels and bottles. Barrels of four different woods (oak, chestnut, acacia and cherry) were used. A total of 57 volatile compounds were analysed by Gas Chromatography–Flame Ionization Detection (GC–FID) and Headspace Sorptive Extraction GC–Mass Spectrometry (HSSE-TD–GC–MS). We observed significant increases in the total content of volatile compounds only for balsamic vinegars. The concentrations of ethyl furoate, ethyl benzoate, benzaldehyde and acetophenone were highest in cherry barrels. These compounds, then, seem to be characteristic of this wood. Oak lactones presented the highest increases for vinegars aged in oak. Eugenol was only present in vinegars aged in chestnut and oak barrels. Oak and cherry seem to be the best type of wood for aging of vinegar due to their distinctive aromatic characteristics.     

Incineration of different types of medical wastes: emission factors for particulate matter and heavy metals

Previously published results for emission factors of medical waste incineration do not include enough information about the incinerated waste composition. This paper reports the first emission factors estimated for particulate matter, As, Cd, Cr, Pb, Mn, Hg, and Ni, considering that medical waste is segregated in different types according to Portuguese legislation. The main purpose was to evaluate the influence of incinerated waste composition and segregation practice on emission factors. One "controlled-air" incinerator without air pollution control devices was used for the incineration either of mixtures with a defined composition or of a specific waste type. Previously published emission factors are not associated with the composition of the incinerated mixture, and the results showed that the usefulness of those emission factors is very doubtful. The existence of different waste classifications also reduces the usefulness of previously published results. To protect human health, appropriate equipment to control atmospheric pollutants must be used, since the legal limits for pollutant concentrations were strongly surpassed (226 times higher than the limit for Hg), with risks for patients and workers of the hospital and exposed population. It was concluded that rigorous segregation practices and adequate management methodologies allow reducing 80% of the amount of wastes that must be incinerated, practically eliminating Hg and Pb emissions and reducing those of PM, As, Cd, Cr, Mn, and Ni, respectively, 98, 90, 92, 84, 77, and 92%.     

不同类型和水平VE在肉鸡肌肉、皮肤和腹脂中的沉积

研究不同类型和水平VE在肉鸡肌肉、皮肤和腹脂中沉积的差异.结果表明:(1)同类型VE组相比,高水平组肉鸡的肌肉、皮肤和腹脂中的VE总量均显著高于低水平组(P＜0.05);(2)天然α-生育酚组肌肉和皮肤中的VE总量显著高于同水平的合成α-生育酚组和天然混合 VE 组(P＜0.05);(3)天然混合 VE 组肉鸡肌肉、皮肤和腹脂中的α-生育酚的沉积率低于同水平的合成α-生育酚组和天然α-生育酚组,而γ-生育酚的沉积率均高于同水平的其他两组;(4)天然混合 VE 或天然α-生育酚水平的提高会增加α-生育酚在皮肤中的沉积率;(5)肌肉中α-生育酚的沉积率高于γ-生育酚.     

电子舌对不同品种醋的辨别研究

电子舌技术是一种分析、识别液体味道的新型检测手段,在食品工业中的应用正逐步扩展.研究利用AstreeII电子舌对不同类型和产地的9个品种的醋在5种不同的稀释浓度下进行检测和分析,建立了Fisher多级判别模型,实验结果表明在醋样稀释倍数为12.5×10倍时.模型的正确识别率达到97.53%,同时在该稀释倍数下,运用聚类分析方法定量计算9种醋的差异程度,并绘出它们的聚类关系图,直观地反映了9种醋之间的关联性,得到良好的辨别效果.实验结果对醋真假的鉴别有一定的借鉴意义.     

HS-SPME-GC-MS测定食醋中羟甲基糠醛衍生物的研究

利用顶空固相微萃取串联气相色谱质谱法（HS-SPME-GC-MS）测定食醋中羟甲基糠醛（HMF）衍生物,评估不同食醋中羟甲 基糠醛衍生物的含量差异及其对食品安全的影响。 从食醋中鉴定出糠醛,5-甲基糠醛和2-乙基-1-己醇共3种羟甲基糠醛衍生物,加标 回收率在81.62%～96.47%之间。 利用该方法测定的市售五种食醋中,糠醛含量最高为7 077.31 μg/L,最低为179.23 μg/L,5-甲基糠醛 含量最高为684.27 μg/L,最低为260.47 μg/L,2-乙基-1-己醇含量最高为107.21 μg/L,最低为62.13 μg/L。 以上结果表明,不同食醋中羟 甲基糠醛的含量具有显著差异（P＜0.05）,但日常的食醋量不会引起人体不良反应。     

电子舌技术在食醋口感评价中的应用

对5个不同地区的17种代表性食醋用电子舌专一型传感器进行了检测分析,同时参照国标检测了该批食醋的3种理化指标(总酸值、氨基态氮值、食盐含量)。将所得电子舌分析结果进行了主成分分析(PCA)及聚类分析(CA)。结果表明,电子舌在不同程度上能对17种食醋进行区分,香醋、陈醋、米醋滋味较接近,而与红曲醋滋味差异较大;并利用Excel对酸味传感器、咸味传感器和鲜味传感器检测所得信号值进行宏计算,得出酸味、咸味、鲜味3种滋味的强度分值,然后与理化指标数值相比对,结果表明总酸值与酸感强度完全符合,食盐含量与咸感有一定相关,氨基态氮值与鲜感呈现非相关。     

Aging characteristics of different beer types

Eight commercial beers (3 lager beers, 2 dark ales and 3 high-alcoholic ales) were aged for one year under normal storage conditions, and the changes with time of flavour profile and the concentration of 15 volatile compounds were monitored. The compounds were chosen as markers to evaluate the importance of different reactions in the aging process of each beer type. The development of typical aging flavours during beer storage could be linked to the Maillard reaction, the formation of linear aldehydes, ester formation, ester degradation, acetal formation, etherification and the degradation of hop bitter compounds. A difference in the nature of aging flavours between lager and specialty beers was found and seemed to be mainly the result of an increased Maillard reaction in specialty beers. Based on the results, some practical strategies are proposed to improve the flavour stability, depending on the beer type.     

Total hordatine content in different types of beers

Hordatines are phenolic secondary metabolites typical of barley. Hordatines withstand at least moderate processing, and thus they are also found in barley malts and beer. So far, no published data on the hordatine content has been available in beers or different styles of beer. The aim of this study was to produce information on the total hordatine content in beers and statistically compare the hordatine content of different beer types. In the current study, hordatines were analysed in 208 beers by high‐performance liquid chromatography equipped with a diode array detector (HPLC‐DAD). The average total hordatine content of all beer samples was 5.6 ± 3.1 mg L^?1 as p‐coumaric acid equivalents (PCAE), with a minimum values 0 to a maximum value 18.7 mg L^?1 PCAE. The total hordatine content correlated positively to the alcohol content in lagers, ales, stouts and porters, but not in wheat beers. There was no statistically significant difference in hordatine content in different types of beer, excluding the non‐alcoholic group of beers. It is noteworthy that non‐alcoholic beers also contained hordatines. More research would be needed to understand how parameters, such as mashing, should be chosen in order to achieve maximum recovery of hordatines in wort and beer.     

Consumer acceptance of new strawberry vinegars by preference mapping

Consumers’ acceptance of new strawberry vinegars was evaluated, and trained panellists described their sensory profiles. Four strawberry vinegars, three produced from puree and one from cooked must, were evaluated jointly. Due to obtaining the highest percentage of consumer acceptance, cooked strawberry must vinegar was considered to be the best. This vinegar stood out in general impression, raisin, and liqueur attributes. Internal preference maps confirmed a higher acceptance level for the strawberry vinegars over commercial vinegar. External preference mapping, obtained by PLS2 analysis, revealed that the main sensory attributes driving consumers’ preferences are raisin, toasted caramel, spicy, and liqueur aroma.