Melatonin is synthesised by yeast during alcoholic fermentation in wines

Melatonin (N-acetyl-5-methoxytryptamine) is a neurohormone produced in the pineal gland. Its biological properties are related to the circadian rhythm. Recently, the European Food Safety Authority (EFSA) accepted the health claim related to melatonin and the alleviation of subjective feelings of jet lag. This molecule has been detected in some foods. In this work, 13 grape varieties were studied; 7 monovarietal wines were produced in an experimental winery under strictly controlled conditions and were sampled in different steps. The grape varieties used to make the wines were: Cabernet Sauvignon, Merlot, Syrah, Tempranillo, Tintilla de Rota, Palomino Fino and Alpha red. Liquid chromatography tandem mass spectrometry (LC-MS/MS) unequivocally confirmed the presence of melatonin in wines. The main contribution of this paper is the results that clearly show that melatonin is synthesised during the winemaking process, specifically after the alcoholic fermentation. Indeed, melatonin is absent in grapes and musts and is formed during alcoholic fermentation.     

Phenolic characterisation of red wines from different grape varieties cultivated in Mendoza province (Argentina)

BACKGROUND: Knowledge of the chemical composition of wine and its association with the grape variety/cultivar is of paramount importance in oenology and a necessary tool for marketing. Phenolic compounds are very important quality parameters of wines because of their impact on colour, taste and health properties. The aim of the present work was to study and describe the non‐flavonoid and flavonoid composition of wines from the principal red grape varieties cultivated in Mendoza (Argentina). RESULTS: Sixty phenolic compounds, including phenolic acids/derivatives, stilbenes, anthocyanins, flavanols, flavonols and dihydroflavonols, were identified and quantified using high‐performance liquid chromatography with diode array detection coupled with electrospray ionisation mass spectrometry (HPLC‐DAD/ESI‐MS). Marked quantitative differences could be seen in the phenolic profile among varieties, especially in stilbenes, acylated anthocyanins and other flavonoids. CONCLUSION: The polyphenolic content of Malbec wines was higher compared with the other red varieties. Dihydroflavonols represent a significant finding from the chemotaxonomic point of view, especially for Malbec variety. This is the first report on the individual phenolic composition of red wines from Mendoza (Argentina) and suggests that anthocyanins, flavanols and phenolic acids exert a great influence on cultivar‐based differentiation. Copyright © 2011 Society of Chemical Industry     

霞多丽葡萄自然发酵过程中酵母种群的分布与变化规律

采用WL形态学归类分析和5.8S-ITS rDNA PCR-RFLP分子生物学鉴定方法,对我国2个主要产区所产白葡萄品种霞多丽自然发酵过程中的酵母种群进行了系统研究。结果表明,从霞多丽葡萄发酵液中分离到7个酵母菌种,不同产区霞多丽发酵液中分布酵母菌的种类和数量有一定差别,但在发酵过程中酵母种群的变化趋势是一致的。     

Influence of yeast strain on binding of sulphur dioxide in wines,and on its formation during fermentation

The amounts of sulphur dioxide bound by acetaldehyde, pyruvic acid and α-ketoglutaric acid during fermentation of three grape juices by eight wine yeasts (Saccharomyces sp.) are reported. These constituents accounted for 49–83 % (mean 69) of the measured bound SO₂, depending on the yeast strain and juice. the maximum range of concentrations of the binding components for individual wines were 10–48 ppm for acetaldehyde, 9–77 ppm for pyruvic acid and 5–63 ppm for α-ketoglutaric acid, depending on yeast strain and grape juice. the validity of the calculations was verified by an experiment with SO₂ and the three binding compounds in a multicomponent model system. The acetaldehyde content was related to the total SO₂ present, which itself was determined by the strain of yeast. SOz bound in the wines after a further SO₂ addition was correlated significantly with pyruvic and α-ketoglutaric acids, but not with acetaldehyde. Certain yeasts produced SO₂ during fermentation in grape juice and in synthetic media with defined sulphur sources. More SO₂ was produced at pH 3.6 than 3.0 in the absence of added sulphate in grape juice. Sulphate was the best sulphur source for SO₂ production in synthetic media, although some yeasts were able to produce smaller amounts of SO₂ from l-cysteine and reduced glutathione.     

Discovering a chemical basis for differentiating wines made by fermentation with 'wild' indigenous and inoculated yeasts: role of yeast volatile compounds

Background and Aims:  Winemakers are constantly searching for new techniques to modulate wine style. Exploiting indigenous yeasts present in grape must is re-emerging as a commercial option in New World wine regions. Wines made with indigenous or 'wild' yeasts are perceived to be more complex by showing a greater diversity of flavours; however, the chemical basis for the flavour characteristics is not yet defined. In order to evaluate techniques for making wine with the 'wild yeast fermentation' character more reliably, it is necessary to define the salient chemical characteristics of such wines.
Methods and Results:  Pairs of Chardonnay wines were prepared from the same must and subjected to similar fermentation conditions in the wineries of origin, except for the mode of inoculation. Reference wines were made by inoculation with a Saccharomyces cerevisiae starter culture, whereas companion wines were allowed to undergo fermentation with the indigenous microflora. Of all wine chemicals analysed, only yeast-derived volatile fermentation products showed significant differences between the yeast treatments.
Conclusions:  Inoculated wines were associated with the esters ethyl hexanoate and 3-methylbutyl acetate and formed a clear cluster by principal component analysis. By comparison with inoculated wines, 'wild' yeast fermented wines showed high variability in volatile compounds that contribute to wine aroma, with higher concentrations of 2-methylpropanol, 2-methylbutanoic acid, ethyl 2-methylpropanoate, ethyl decanoate and ethyl dodecanoate potentially being sensorially important.
Significance of the Study:  This study shows that yeast-derived volatile fermentation products are a key difference between inoculated and uninoculated ferments and provides a chemical basis for the 'wild yeast fermentation' character.     

Degradation of 5-hydroxymethylfurfural during yeast fermentation

5-Hydroxymethyl furfural (HMF) may occur in malt in high quantities depending on roasting conditions. However, the HMF content of different types of beers is relatively low, indicating its potential for degradation during fermentation. This study investigates the degradation kinetics of HMF in wort during fermentation by Saccharomyces cerevisiae. The results indicated that HMF decreased exponentially as fermentation progressed. The first-order degradation rate of HMF was 0.693 × 10(-2) and 1.397 × 10(-2)min(-1) for wort and sweet wort, respectively, indicating that sugar enhances the activity of yeasts. In wort, HMF was converted into hydroxymethyl furfuryl alcohol by yeasts with a high yield (79-84% conversion). Glucose and fructose were utilised more rapidly by the yeasts in dark roasted malt than in pale malt (p<0.05). The conversion of HMF into hydroxymethyl furfuryl alcohol seems to be a primary activity of yeast cells, and presence of sugars in the fermentation medium increases this activity.     

Degradation of 5-hydroxymethylfurfural during yeast fermentation

5-Hydroxymethyl furfural (HMF) may occur in malt in high quantities depending on roasting conditions. However, the HMF content of different types of beers is relatively low, indicating its potential for degradation during fermentation. This study investigates the degradation kinetics of HMF in wort during fermentation by Saccharomyces cerevisiae. The results indicated that HMF decreased exponentially as fermentation progressed. The first-order degradation rate of HMF was 0.693?×?10^?2 and 1.397?×?10^–2?min^?1 for wort and sweet wort, respectively, indicating that sugar enhances the activity of yeasts. In wort, HMF was converted into hydroxymethyl furfuryl alcohol by yeasts with a high yield (79–84% conversion). Glucose and fructose were utilised more rapidly by the yeasts in dark roasted malt than in pale malt (p?<?0.05). The conversion of HMF into hydroxymethyl furfuryl alcohol seems to be a primary activity of yeast cells, and presence of sugars in the fermentation medium increases this activity.     

树莓酵素中耐高渗酵母菌的分离鉴定及生长特性研究

从树莓酵素中分离酵母菌,通过形态学特征、生理生化指标及26S r DNA序列分析进行鉴定,并对其生长特性进行研究,以期为植物酵素食品生产提供酵母菌资源。鉴定结果表明:分离出的Y1、Y2、Y3三株菌形态学特征相似,且均可在高糖环境下生长,26S r DNA序列与鲁氏接合酵母的同源相似性均高于99%,确定Y1、Y2、Y3均为鲁氏接合酵母(Zygosaccharomyces rouxii,Z.rouxii);生长特性研究结果表明:当培养基初始葡萄糖含量为300、450、600、750 g/L时,该菌种均可生长,延滞期分别为12、12、36、60 h,葡萄糖初始含量为900 g/L,生长缓慢;当培养基初始pH为1.5和2.0时,菌种的生长受到抑制,当pH为2.5、3.0、3.5时,菌种可以生长,延滞期分别为96、48、48 h。鲁氏接合酵母为树莓酵素中的优势酵母,具有耐高糖、耐低pH等耐高渗特性。      

Partial characterization of peptides from red wines. Changes during malolactic fermentation and ageing with lees

The peptide fraction of an industrially manufactured red wine has been studied during malolactic fermentation, carried out in stainless-steel tanks or in the barrel and ageing in the barrel, with or without lees, for 12 months. Peptides were fractionated using Sephadex LH-20 and Cosmosil 140 C₁₈-OPN columns, giving two fractions in relation to peptide polarity. The most important changes were detected during malolactic fermentation and during the ageing in barrel with lees. The peptides present in the wine could be glycopeptides from grape or yeast. Most amino acids in the most polar peptides were aspartic acid and/or asparagine, glutamic acid and/or glutamine, serine, glycine, α-alanine and tyrosine and, in the less polar fraction, were glycine, α-alanine and leucine. The amino acid distribution is most different in the most polar fraction, among the studied wines, owing to autolysis and hydrolysis of the polypeptides and proteins.     

Increased flavour diversity of Chardonnay wines by spontaneous fermentation and co-fermentation with Hanseniaspora vineae

Discovery, characterisation and use of novel yeast strains for winemaking is increasingly regarded as a way for improving quality and to provide variation, including subtle characteristic differences in fine wines. The objective of this work was to evaluate the use of a native apiculate strain, selected from grapes, Hanseniaspora vineae (H. vineae) 02/5A. Fermentations were done in triplicate, working with 225 L oak barrels, using a Chardonnay grape must. Three yeast fermentation strategies were compared: conventional inoculation with a commercial Saccharomyces cerevisiae strain, ALG 804, sequential inoculation with H. vineae and then strain ALG 804 and spontaneous fermentation. Yeast strain identification was performed during fermentation, in which the apiculate strain was found to be active, until 9% of alcohol in volume, for the co-fermentation and the spontaneous fermentation was completed by three native S. cerevisiae strains. Basic winemaking parameters and some key chemical analysis, such as concentration of glycerol, biogenic amines, organic acids, and aroma compounds were analysed. Sensory analysis was done using a trained panel and further evaluated with professional winemakers. Sequential inoculation with H. vineae followed by S. cerevisiae resulted in relatively dry wines, with increased aroma and flavour diversity compared with wines resulting from inoculation with S. cerevisiae alone. Wines produced from sequential inoculations were considered, by a winemaker’s panel, to have an increased palate length and body. Characteristics of wines derived from sequential inoculation could be explained due to significant increases in glycerol and acetyl and ethyl ester flavour compounds and relative decreases in alcohols and fatty acids. Aroma sensory analysis of wine character and flavour, attributed to winemaking using H. vineae, indicated a significant increase in fruit intensity described as banana, pear, apple, citric fruits and guava. GC analysis of the relative accumulation of 23 compounds to significantly different concentrations for the three fermentation strategies is discussed in relation to aroma compound composition.     

Technological conditions influence aminogenesis during spontaneous sausage fermentation

The influence of two manufacturing processes on biogenic amine formation during the manufacture of Spanish dry fermented sausages of different diameters (fuet and llonganissa) was evaluated to elucidate which conditions allow better control of the aminogenic activity of spontaneous microbiota. Technological conditions affected both the amounts and the qualitative profile of biogenic amine accumulated. The higher processing temperature and relative humidity in process A (simulating those applied in industrial manufacture) favoured aminogenesis, since biogenic amine accumulation was faster and higher than in sausages manufactured under the process B (close to those used in traditional practices). The major amine differed depending on the diameter of the sausages, tyramine being the major amine in fuet (2.5 cm diameter sausage), and putrescine in llonganissa (4.5 cm). Moreover, sausages of higher diameter (llonganissa) had higher biogenic amine contents compared with the thinnest sausages (fuet). Conditions would modulate biogenic amine accumulation not only due to its influence on development of the bacterial population but also on its aminogenic activity. From the biogenic amine point of view, when sausages are spontaneously fermented, traditional lower temperatures and relative humidities are more appropriate than those usually applied in industrial processes.     

Probiotic potential of indigenous yeasts isolated during the fermentation of table olives from Northeast of Portugal

The aim of this study was to evaluate the probiotic potential of 16 yeast strains previously isolated during the natural fermentation of table olives Negrinha de Freixo cultivar, in relation to enzymatic activities; ability to grow at 37 °C; antimicrobial activity; autoaggregation capacity; antioxidant activity and survival in gastrointestinal tract conditions. The highest antioxidant activity was observed for Saccharomyces cerevisiae, similar to the reference strain S. boulardii. Candida norvegica 7A and Galactomyces reessii 34A showed antifungal ability to the pathogenic microorganism Cryptococcus neoformans. Regarding the autoaggregation capacity, S. cerevisiae 15A, C. tropicalis 1A and C. norvegica 7A showed > 80% after 24 h. Pichia guilliermondii 25A and C. norvegica 7A were the most resistant to the simulated digestive conditions, similar to the reference strain (S. boulardii). Thus, these results suggest that some yeast strains involved in the fermentation of table olives have probiotic potential.Industrial relevanceIn this study, we highlight the probiotic potential of yeast microbiota usually found in green table olives. These yeast strains could be used as culture starters for the development of new functional products.     

梅鹿辄葡萄自然发酵酵母菌群研究

利用WL营养培养基对梅鹿辄葡萄自然发酵过程中分离到的98株酵母菌进行初步鉴定,进而对代表性的菌株进行5.8S rDNA-ITS区PCR产物的限制性内切酶酶切分析.结果表明,供试的98株酵母菌属于3属3个种,分别为酿酒酵母(Saccharomyces cerevisiae)、东方伊萨酵母(Issatchenkia orientalis)、克鲁维毕赤酵母(Pichia kluyver),3种酵母菌分别占分离自该葡萄品种总酵母菌株的80.61％、13.26％、6.13％.在自然发酵的初期和中期,酵母菌的比例因是否添加SO2而有所差异,但发酵末期均以S.cerevisiae为优势菌.     

Effect of sulfur dioxide addition in wild yeast population dynamics and polyphenolic composition during spontaneous red wine fermentation from Vitis vinifera cultivar Agiorgitiko

The aim of the present study was to assess the effect of sulfur dioxide addition in the wild yeast population dynamics as well as the polyphenolic composition during spontaneous red wine fermentation from Vitis vinifera cultivar Agiorgitiko. The grapes were crushed and fermentation took place at 21 °C without the addition of any commercial yeast, and with and without the addition of 40 mg L^?1 SO₂. A combination of culture-dependent and culture-independent techniques was used for wild yeast population dynamics assessment and HPLC analysis for the determination of polyphenolic compounds. Regarding the former, the effect of sulfur dioxide addition was only marginal since Saccharomyces cerevisiae strains dominated the fermentation from the first day; strains belonging to Hanseniaspora spp., Lachancea thermotolerans and Metschnikowia pulcherrima species appeared only occasionally. As far as the polyphenolic content was concerned, it was enhanced with sulfur dioxide addition; however, as time progressed, the differences were reduced, suggesting that the time the juice was in contact with the skins was of greater importance than sulfur dioxide addition.     

Development of the microbial community during spontaneous cauliflower fermentation

The aim of this study was to assess the changes in the microbial ecology during spontaneous cauliflower fermentation and to taxonomically characterize the dominating lactic acid microbiota. For this purpose, cauliflower fermentation was performed according to a traditional recipe originating from northern Greece. Lactic acid bacteria dominated fermentation already from the 3rd day. Phylogenetic analysis based on partial 16S-rRNA gene sequences exhibited that spontaneous cauliflower fermentation was characterized by an initial heterofermentative stage driven by strains belonging to Leuconostoc mesenteroides-group that was followed by a homofermentative one with strains of Lactobacillus plantarum-group dominating. Strains belonging to Enterococcus faecium-group and Enterococcus faecalis-group were also isolated but only at the early stages of fermentation.     

酵母发酵对杏原料中氰化物的降解作用

杏中含有微量的氢氰酸，使其食用受到一定限制。在杏酒的开发过程中，对酵母酒精发酵是否能减少氢氰酸的含量作了探索研究。在采用的4种葡萄酒活性干酵母中，1号酵母菌和3号酒精发酵完成后，氰化物含量分别减少了56．7％和32．2％；2号酵母菌和4号酵母菌降解率低于10％。采用1号酵母菌的研究表明，随着发酵的进行氰化物含量逐步减少，在第6d降至最低。研究结果可能对利用微生物发酵解除或降低食品原料中有毒物质有所启发。     

啤酒废酵母抽提物促进啤酒酵母发酵的研究

利用啤酒废酵母制备得到的酵母抽提物对啤酒酵母发酵性能的影响来检测所制酵母抽提物的品质,并与英国OXOID公司进口酵母粉进行对照分析。实验结果表明,添加酵母抽提物提高了啤酒酵母的起发速度、发酵效率和存活率,并增强了所制啤酒的缓冲能力、风味稳定性和抗氧化能力,且自制酵母抽提物促进啤酒酵母发酵的效果略优于OXOID酵母粉。     

Histamine production by bacilli bacteria, acetic bacteria and yeast isolated from fruit wines

Eleven red wines imported from foreign country and 40 domestic fruit wines, including 15 red wines, 4 white wines, 7 plum wines, and 14 other fruit wines, sold in the supermarkets in Taiwan were purchased and tested to determine the occurrence of biogenic amines and histamine-forming bacteria. The levels of pH, total soluble solids (TSS), titratable acidity (TA), reducing sugar (RS), total sugar (TS), sulphites, methanol (milligram per liter of pure ethanol), ethanol and Pb in all samples ranged from 3.0 to 4.1, 6.8 to 24.4 °Brix, 0.3 to 1.7 g/100 mL, 0.2 to 17.6 g/100 mL, 1.6 to 28.4 g/100 mL, <2 to 260.5 mg/L, <1 to 2559 mg/L, 5.0 to 15.6 g/100 mL and <1 to 46.2 μg/L, respectively. The levels of TSS, TA, RS, and TS in plum wine samples were significantly higher than those of the other wines samples, whereas the pH value in plum wine samples was lower than that of the other wines samples. The average content for each of the nine biogenic amines in all samples was less than 5.2 mg/L. However, higher levels of histamine and spermine were detected in domestic fruit wine samples than the imported red wine samples. Five histamine-forming isolates isolated from domestic red wine and jackfruit wine, capable of producing 13.0 mg/L to 69.1 mg/L of histamine in trypticase soy broth (TSB) supplemented with 2 g/100 mL l-histidine (TSBH) or MRS broth supplemented with 2 g/100 mL l-histidine (MRSH), were identified as Bacillus pumilus (one strain), Bacillus sp. (two strains) and Acetobacter pasteurianus (one strain) by 16S rDNA sequencing with PCR amplification, and Zygoascus hellenicus var. hellenicus (one strain) by internal transcribed spacer sequencing with PCR amplification. To our knowledge, this is the first report to demonstrate the occurrence of histamine-forming bacilli bacteria, acetic bacteria and yeast in fruit wine.