Chemiotropic behavior of female olive fly (Bactrocera oleae GMEL.) onOlea europaea L

An interpretation is given of a number of observations on the chemiotropic behavior ofBactrocera oleae in connection with olive maceration water and the fly's return to the olive groves after the first summer rains. To this end, the headspace of both maceration water and leaf leaching water, simulating rainfall, were examined. In both cases, the presence of ammonia, which is generally known to attract fruit flies (Diptera, Tephritidae), was detected and, for the first time, in addition to other compounds that are inert for the fly, the presence of styrene was also detected. This aromatic hydrocarbon was found to be a strong attractant. It is shown that both ammonia and styrene are products of the metabolism of microbial flora present on the olive and leaf surface.     

Impact of various maceration techniques on the phenolic and volatile composition of Chenin Blanc wines

Chenin Blanc, cultivated in cool climate regions, was chosen to evaluate the impact of different maceration techniques on polyphenolic profiles and volatile compounds. Control with no skin contact (CK), cold maceration (CM), cryogenic maceration (CR), separate fermentation before blending (SFB) and extended skin contact during fermentation (ESF) were the five maceration techniques being studied. SFB and ESF techniques resulted in significantly increased polyphenolic compounds compared to the control (P < 0.05), while CM and CR maceration techniques resulted in almost no effect. Meanwhile, for aromatic components, the maximum change was observed in ESF wine, which had significantly highest levels of terpenes, alcohols, esters and acids. However, compared with control wine, CR wine had higher levels of terpenes and esters and SFB wine had higher levels of terpenes and alcohols. This study provides information about prefermentation techniques and additional options for oenologists to produce Chenin Blanc wines with different characteristics.     

Colour features and pigment composition of Italian carbonic macerated red wines

Thirty commercially available Italian carbonic macerated young red wines, have been analysed by HPLC–DAD–MS with the aim to characterise their pigment composition and find possible correlations with the colour features evaluated by means of spectrophotometric measurements. The composition in anthocyanin monoglucosides, acetates, p-coumarates as well as that in pyranoanthocyanins and direct and ethyl-bridged adducts with flavanols, was studied. Because of the peculiar maceration process, carbonic macerated wines demonstrated to be qualitatively rich in pyranoanthocyanins and pigment adducts. A number of ethyl-bridged anthocyanin isomers was found, together with significant contents of vitisin A and vitisin B (up to 15.5 mg/L as a sum). Malvidin-3-glc-4-vinylphenol was the main pyranoanthocyanin-vinylphenol adduct (up to 1.10 mg/L). The colour features of the wines were broadly distributed as a consequence of the percentage of carbonic macerated wine present in the marketed product. The statistical treatment of the entire data set revealed that pyranoanthocyanins are positively correlated with colour density (while no correlation was found for monoglucosides) and that direct adducts and/or ethyl-bridged compounds can play a role for what concerns the hue of carbonic macerated wines.     

Enzymatic Maceration: Effects on Volatile Components of Mango Pulp

A decrease of 50% or more of the relative viscosity of mango pulp resulted from different times of maceration with pectolyase and with 3 of the 4 commercial enzyme preparations tested. The microscopic observations after treatment I showed a suspension of cells without destruction of cell walls, fiber remaining in some cases. There was no significant degradation of cellulose and a slight degradation of hemicellulose during treatment. A stability test based on i centrifugation indicated that the macerate was stable for a i relative viscosity decrease <50%. Aroma compound concentrations were not significantly affected by the pectolyase treatment, as only 6 oxygenated terpene compounds, probably released by acid hydrolysis from glycosides were noted.     

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。     

Characterisation of the main enzymatic activities present in six commercial macerating enzymes and their effects on extracting colour during winemaking of Monastrell grapes

Numerous studies have reported on the use of enzymes in wineries to facilitate the extraction of grape phenolics and to aid colour stability, although no clear conclusions were reached. Information concerning the enzymatic activities of industrial preparations is very difficult to obtain despite its importance. The aim of this work was to characterise and quantify the activities of six macerating enzyme preparations to optimise their use, and to study their effect on the chromatic characteristics of a Monastrell wine. The results indicate that differences exist in the type of enzymatic activities present in the preparations and in their concentration. The chromatic characteristics of the resulting wines, both at the end of alcoholic fermentation and after 12 months of storage in stainless steel tanks, showed differences with the use of the different maceration enzymes when comparing with control wine, although very little differences were observed between the different enzyme treatments. The enzyme-treated wines showed, at the end of alcoholic fermentation, a higher OD₂₈₀ and tannin content, and after 12 months, a higher colour intensity too. The main effect of all the preparations was an increase in the total phenol content, probably by facilitating the release of skin tannins.     

Fresh plant tissue softening by means of an immobilized soluble-insoluble endopectinlyase

An endopectinlyase (E.C. 4.2.2.10) immobilized on a reversible soluble-insoluble polymer was used for macerating fresh carrot tissue. the macerating capability of the immobilized enzyme was found to be similar to that of its free form. Losses of catalytic activity detected in the subsequent biocatalyst utilization cycles seem to be related to co-precipitation phenomena following the recovery of the immobilized enzyme from the reaction mixture. Preliminary studies were carried out on the possibility of removing the inhibiting compounds and subsequently restoring biocatalyst activity.     

"十二岭"青梅酒的研制

以广东云浮优质成熟青梅为原料,对“十二岭”梅子酒发酵工艺进行研究。正交试验及感官品评确定其生产工艺为：将青梅粉碎后添加80mg／L的果胶酶进行酶解浸渍,酶解温度为15℃,时间12h,酶解完成后,加入酒石酸钾调整酸度为8g／L,然后添加M05酵母1．5g／L,在20℃下进行发酵48h后,作澄清分离,补加糖分后继续发酵．使其最终酒度在12％vol。最后经调配、澄清、冷冻、除菌过滤、包装后得到酒体丰满、晶莹剔透,呈浅黄色、口感醇厚圆润、爽怡细腻的梅子酒。     

Optoelectronic sensor device for monitoring the maceration of red wine: Design issues and validation

Enologists usually rely on spectrophotometers to perform the chromatic characterization of red wines. This work reports an optoelectronic instrument based on absorbance measurements aiming not only at the assessment of the chromatic characteristics of finished red wines, but at the supervision of the gradual maceration of fermenting grape musts as well. Maceration is a chemical process that takes place during the early stages of the fermentation that finally results in red wine. It is through maceration that wine acquires its distinctive chromatic features. Key issues related to the selection of optoelectronic components, the system design and its final validation using diluted wine samples are thoroughly discussed. Resolution figures lie in the range of one thousandth of an absorbance unit. Maceration has been successfully monitored with the proposed instrument using grape must samples extracted during the first three days from two different fermentations.