Raspberry wine fermentation with suspended and immobilized yeast cells of two strains of Saccharomyces cerevisiae

The objectives of this study were to assess the differences in fermentative behaviour of two different strains of Saccharomyces cerevisiae (EC1118 and RC212) and to determine the differences in composition and sensory properties of raspberry wines fermented with immobilized and suspended yeast cells of both strains at 15 °C. Analyses of aroma compounds, glycerol, acetic acid and ethanol, as well as the kinetics of fermentation and a sensory evaluation of the wines, were performed. All fermentations with immobilized yeast cells had a shorter lag phase and faster utilization of sugars and ethanol production than those fermented with suspended cells. Slower fermentation kinetics were observed in all the samples that were fermented with strain RC212 (suspended and immobilized) than in samples fermented with strain EC1118. Significantly higher amounts of acetic acid were detected in all samples fermented with strain RC212 than in those fermented with strain EC1118 (0.282 and 0.602 g/l, respectively). Slightly higher amounts of glycerol were observed in samples fermented with strain EC1118 than in those fermented with strain RC212. Copyright © 2014 John Wiley & Sons, Ltd.     

甘蔗酒酿造酵母的筛选

选择常用商业果酒酵母菌株KD、DV10、Q23、EC1118、安琪和H7Y7作为供试酵母菌株,以川蔗17为原料发酵生产甘蔗酒,通过分析发酵液中糖含量变化情况及酒精度、澄清度,比较不同菌株发酵特性,结果发现EC1118菌株发酵彻底,产酒能力最强,发酵后甘蔗酒的高级醇含量最低;H7Y7菌株发酵的甘蔗酒中酯类物质最高,为其他菌株的3～6倍;安琪酵母发酵液最易澄清,但其发酵后的甘蔗酒中甲醇含量为其他菌株的5倍以上。感官评分结果显示,不同酵母菌株发酵的甘蔗酒感官评分依次为H7Y7EC1118DV10安琪酵母Q23KD。研究结果表明,供试酵母菌株中EC1118和H7Y7更适宜用于甘蔗酒酿造。     

Optimization of sourdough process for improved sensory profile and texture of wheat bread

The aim of the study was to determine optimum sourdough process conditions for improved flavour and texture of wheat bread. The influence of process conditions and the starter culture on the characteristics of wheat sourdough bread was established by using response surface methodology. Influence of fermentation temperature (16-32 °C), ash content of flour (0.6-1.8 g/100 g), and fermentation time (6-20 h) were considered as independent factors and their effects were studied in sourdough bread fermented with Lactobacillus plantarum, Lactobacillus brevis, Saccharomyces cerevisiae or with a combination of yeast and lactic acid bacteria. Intensity of sensory attributes, specific volume and bread hardness were considered as the main responses. Ash content of flour and fermentation time were the main factors determining the intensity of sensory attributes. The possibility to enhance intensity of overall flavour, aftertaste and roasted flavour without excessive pungent flavour and without reduced fresh flavour in wheat bread containing 20 g sourdough/100 g of wheat dough was demonstrated by choosing e.g. Lb. brevis for a starter and by utilization of high ash content of flour, long fermentation time and reduced temperature. Bread specific volume was improved 0.2-0.5 ml/g and hardness was reduced (after 4 days of storage) up to 260 g by using low ash content of flour and by optimizing fermentation time according to the microbial strain. Lactic acid fermentation had more profound influence on both desired and undesired flavour attributes, as well as textural features of bread in comparison with yeast fermentation.     

Effect of ammonium nitrogen supplementation of grape juice on wine volatiles and non-volatiles composition of the aromatic grape variety Albariño

Vitis vinifera cv. Albariño is an aromatic variety characterised by terpenes present largely as glycosidic flavour precursor compounds, which depends on fermentation to reveal its aromatic varietal potential. Clarified Albariño must containing 250 mg N/L (control) was supplemented with diammonium phosphate to 350 and 450 mg N/L before fermentation with a high-nitrogen-demand wine strain of Saccharomyces cerevisiae (M05). Ammonium supplementation had a significant effect on the chemical composition (titratable acidity and ethanol) and volatile profile of Albariño wines. Varietal compounds in the free fraction (limonene, linalool, α-terpineol, α-ionone and β-damascenone) and bound (limonene, linalool and α-terpineol), as well as most yeast-derived fermentation products (including esters, higher alcohols and volatile acids) were associated with moderate nitrogen concentrations. Free β-ionone, bound geraniol, bound α-ionone, bound β-damascenone and 1-hexanol were associated with high nitrogen concentrations. OAV wines made with moderate nitrogen exhibited a higher total odorant activity, driven by ethyl esters, terpenes and C₁₃-norisoprenoids, resulting in fruity and floral aroma attributes.     

酵母对香蕉蒸馏酒品质影响及香气成分研究

采用5种酿酒酵母：W15、EC1118、S7、L45、71B进行香蕉浆发酵与蒸馏得到香蕉蒸馏酒。通过对比果酒的酒精度、糖、酸以及蒸馏酒的部分理化指标包括总酸、总酯、香气成分,结合感官评价,筛选出最佳的香蕉蒸馏酒生产用酵母为EC1118,其发酵的原酒酒精度可达15.16°,蒸馏后清亮透明,果香、醇香协调,香蕉香浓郁优雅,入口柔顺绵软,酒体醇厚。具有乙酸乙酯为主体的清雅、谐调的香气和辛酸乙酯的典型香蕉味。     

Redox effect on volatile compound formation in wine during fermentation by Saccharomyces cerevisiae

Although redox state is a well-known key process parameter in microbial activity, its impact on wine volatile aroma compounds produced during fermentation has not been studied in detail. In this study we report the effect of reductive and microaerobic conditions on wine aroma compound production using different initial amounts of yeast assimilable nitrogen (YAN: 180 and 400 mg N/l) in a simil grape must defined medium and two S. cerevisiae strains commonly used in wine-making. In batch fermentation culture conditions, reductive conditions were obtained using flasks plugged with Muller valves filled with sulphuric acid; while microaerobic conditions were attained with defined cotton plugs. It was found that significant differences in redox potential were obtained using the different plugs, and with variation of over 100 mV during the main fermentation period.     

The influence of yeast on the aroma of Sauvignon Blanc wine

The main objective of this study was to investigate the effect of different Saccharomyces cerevisiae wine yeast strains on the concentration of aroma-enhancing volatile thiols and fermentation metabolites in Sauvignon Blanc wine. Seven commercial wine yeast strains were selected based on their putative ability to modulate the concentrations of the fruity volatile thiols, 4-mercapto-4-methylpentan-2-one (4MMP), 3-mercapto-hexanol (3MH) and 3-mercapto-hexylacetate (3MHA). Each of these yeasts was used to produce Sauvignon Blanc wines under controlled conditions, in triplicate, in 20-L quantities. The levels of 4MMP, 3MH and 3MHA in these wines were quantified using the p-hydroxymercuribenzoate method. In addition, a total of 24 volatile yeast-derived fermentation aroma compounds were also quantified using headspace solid-phase microextraction coupled with gas chromatography mass spectrometry (HS-SPME–GC–MS). Formal sensory analysis was conducted by 12 trained assessors and, additionally, a panel of 24 experienced wine industry professionals assessed the wines and ranked them in order of preference. The results indicated that the yeast strains varied significantly in terms of their capabilities to (i) produce volatile thiols and fermentation metabolites; and (ii) to modulate the varietal characters of Sauvignon Blanc wine. Yeast strains that produced the highest levels of volatile thiols were responsible for wines with the highest perceived intensity of fruitiness, and these wines were preferred by the tasting panels. While the ‘green’ characters in Sauvignon Blanc wines can be manipulated through vineyard management, the ‘tropical fruity’ characters appear to be largely dependent on the wine yeast strain used during fermentation. Therefore, the choice of yeast strain offers great potential to modulate wine aroma profiles to definable styles and predetermined consumer market specifications.     

Apple pieces as immobilization support of various microorganisms

The biocatalyst prepared by immobilization of Saccharomyces cerevisiae strain AXAZ-1 on apple pieces was used for fermentation of grape must both in batch and continuous system. The immobilized yeast showed an important operational stability without any decrease of its activity. In continuous process, the bioreactor was operated for 95 days without any diminution of the ethanol productivity. Concentrations of higher and amyl alcohols were low indicating an improved quality product.Apple pieces were also used as support for immobilizing Kluyveromyces marxianus IMB3 for high-temperature (45 °C) wine-making. The fermented grape must contained 3-4% alcohol and semi-sweet wines were produced by the addition of potable alcohol.Preliminary sensory evaluation of the produced wines ascertained the fruity aroma and the overall improved quality compared to other commercially available products.Lactobaccillus casei cells immobilized on apple pieces were used for probiotic, fermented milk and lactic acid production. Apple-supported L. casei used for successive fermentation batches of whey proved to be very effective and suitable for food-grade lactic acid production. The immobilized biocatalyst was also used for milk fermentation and was able to ferment after storage for 15, 98 and 129 days at 4 °C, while no infection was reported during storage periods.     

Effect of postharvest dehydration on the composition of pinot noir grapes (Vitis vinifera L.) and wine

This study was conducted in order to improve our understanding of how phenolics and aroma compounds change in wine grapes during postharvest dehydration. Pinot noir grapes grown in the Willamette Valley of Oregon were harvested at 22.0 and 24.0 °Brix. Grapes harvested at 22.0 °Brix were divided into three equal lots with one lot immediately used for wine production, and the remaining two lots placed inside an air tunnel with an air speed of 1.0–1.8 m s⁻¹, 38% relative humidity and a temperature of 22 °C. The soluble solids content and weight loss were measured daily and wines were made from grapes when they reached 24.8 and 26.7 °Brix. The soluble solids of grapes increased about 1 °Brix per day; therefore, on the third and fourth day the berries reached the desired concentration; weight loss was 14 and 16%, respectively. Results from berry phenolic analysis indicated that per berry anthocyanin amount remained unchanged during dehydration. The composition of proanthocyanidins isolated from berries changed during dehydration. Volatile compounds in wines made from dehydrated grapes contained more terpenes and norisoprenoids (β-ionone, β-damascenone) when compared to wine made from the original fruit. Wines made from increasingly dehydrated grapes tended to resemble the composition and flavour profile of wines made from grapes left on the vine (i.e. with extended ripening). The results of this study suggest that postharvest flavour changes consistent with changes during fruit ripening can occur in grapes when harvested early and allowed to dehydrate under controlled conditions prior to fermentation.     

Nitrogen addition influences formation of aroma compounds,volatile acidity and ethanol in nitrogen deficient media fermented by Saccharomyces cerevisiae wine strains

The effects of nitrogen addition into nitrogen deficient/depleted media on the release of aroma compounds post-fermentation were investigated in three commercial yeast strains of Saccharomyces cerevisiae which highlight the yeast strain effect as well as nitrogen effects. By comparing the two timings of nitrogen addition, prior to fermentation or later at stationary phase (72 h), it was shown that nitrogen addition at stationary phase significantly decreases ethanol and acetic acid formation and significantly increases the following compounds: 2-phenylethanol, ethyl isobutyrate, 2-phenylethyl acetate, ethyl 2-methylbutyrate and ethyl propionate in the three strains, and also isovaleric acid, isoamyl alcohol and ethyl isovalerate in both PYCC4072 and UCD522. The strain EC1118 produced significantly less medium chain fatty acids, hexanoic, octanoic and decanoic acids and their respective esters after nitrogen addition. Therefore, timing of nitrogen addition to a ferment media can vary the concentration of certain aroma compound and might provide a means for varying wine composition.     

两种酿酒酵母混合发酵对赤霞珠干红葡萄酒香气成分的影响

以酵母F15单独发酵为对照,分别添加不同比例的酵母EC1118和F15（1∶9、3∶7和5∶5）混合发酵酿制赤霞珠干红葡萄酒,测定其 基本理化指标,采用搅拌棒吸附萃取（SBSE）和气相色谱-质谱联用（GC-MS）技术提取检测葡萄酒中的香气成分,并进行主成分分析 （PCA）。 结果表明,酵母EC1118和F15混合发酵酿制的葡萄酒的理化指标均符合国家标准GB/T 15037—2006《葡萄酒》,香气成分中 的酯类、醇类和酸类等物质的含量均有所增加。与酵母F15单独发酵相比,酵母EC1118和F15（3∶7）混合发酵可以显著提高赤霞珠干红 葡萄酒的酒精度,增加香气成分（P＜0.05）,增强葡萄酒的果香和花香。     

Production of flavour-active methionol from methionine metabolism by yeasts in coconut cream

Yeasts Candida kefyr NCYC143, Candida utilis CUM, Kluyveromyces lactis KL71, Saccharomyces bayanus SB1, Saccharomyces cerevisiae EC1118, Saccharomyces chevalieri CCICC1028, Candida famata (previously Torulopsis candida) CCICC1041 and Williopsis saturnus var. saturnus CBS254 were screened for their ability to produce flavour-active methionol (3-methylthio-1-propanol) in coconut cream supplemented with l-methionine. The yeasts varied with their ability to produce methionol from methionine with Saccharomyces cerevisiae EC1118 producing the most, followed by Kluyveromyces lactis KL71. Little methionol was produced by the other yeasts. Methionol production by Kluyveromyces lactis KL71 was subjected to further studies under different conditions of initial pH (4.0-6.3), temperature (20-33 °C), l-methionine concentration (0.05-0.25%) and yeast extract concentration (0-0.50%); optimal conditions were established at pH 5.0, 33.0 °C, 0.15% l-methionine and 0.05% yeast extract. CharmAnalysis™ using SPME-GC-MS was conducted on the coconut cream ferment; methional (3-methylthio-1-propanal), methionol and 2-phenylethyl acetate were found to be the most potent aroma-active compounds. The product of coconut cream fermentation by Kluyveromyces lactis KL71 may be considered as a novel, plant-based, natural and complex flavoring bioingredient in food applications.     

Yeast strain affects 3‐isopropyl‐2‐methoxypyrazine concentration and sensory profile in Cabernet Sauvignon wine

Background and Aims: 3‐Isopropyl‐2‐methoxypyrazine (IPMP) is both a grape‐ and insect‐derived trace compound found in wine that can contribute green characters. There has been renewed interest in examining how wine IPMP concentrations can be modulated due to recent concerns regarding ladybug taint – an off‐flavour from IPMP extracted from Harmonia axyridis (Pallas) (multicoloured Asian lady beetle). This study sought to determine the influence of commercial Saccharomyces yeast strains on IPMP concentration in Cabernet Sauvignon wines and to describe their sensory impact. Methods and Results: Rehydrated juice from Cabernet Sauvignon concentrate was spiked with 30 ng/L IPMP and fermented in triplicate by yeast strains Lalvin BM45, Lalvin EC1118, Lalvin ICV‐D21 or Lalvin ICV‐D80. IPMP concentration was determined using headspace solid‐phase micro‐extraction coupled with gas chromatography mass spectrometry (HS‐SPME‐GC‐MS), and was unchanged from juice levels in wine fermented by EC1118, Lalvin D21 and Lalvin D80 but increased by 11 ng/L (29%) in wine fermented by Lalvin BM45. Yeast strains differed in their sensory impact on wine made from IPMP‐spiked juice for five aroma and four flavour attributes. Conclusions: HS‐SPME‐GC‐MS allows for sensitive measurement of IPMP that, for the first time, has demonstrated the capacity for wine yeast to affect IPMP concentration. Yeast strains demonstrate varying ability to mask green or ladybug taint characters in wine. Significance of the Study: This information should be useful in guiding selection of yeast strains for juices of high IPMP concentration, including those that are multicoloured Asian lady beetle‐affected, under‐ripe or from varieties with high methoxypyrazine loads such as Cabernet Sauvignon.     

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.     

Influence of SO2 on the consumption of nitrogen compounds through alcoholic fermentation of must sterilized by pulsed electric fields

The aim of this work was to study the influence of SO₂ on the use of nitrogenous compounds by yeast during wine alcoholic fermentation. Thus Parellada must was sterilized by a pulsed electric field treatment and inoculated with Saccharomyces cerevisiae Na33 strain. The fermentations were carried out with SO₂ (20 mg/l) and without SO₂. Results showed that yeast better consumed the amino acids in the first half of fermentation in the presence of SO₂. The final concentration of amino acids in the obtained wine was greater when the must was fermented without SO₂ than when the latter compound was present. Therefore, the presence of SO₂ facilitated the consumption of amino acids and, hence, such wine should have more complex flavour and better microbiological stability than that obtained from fermentation without SO₂.     

香梨全果果浆与果汁发酵工艺及果酒香气成分分析

本研究以库尔勒香梨为试验原料,研究了EC118、KI、KD三种酵母在全果果浆与果汁发酵过程中发酵醪的基本理化指标,且对香梨果实与6种处理果酒的香气成分进行了分析。三种酵母在全果果浆与果汁发酵过程中各指标总体变化趋势没有表现出处理间差异,但各指标的变化水平存在一定的差异,6种果酒总酚含量为244.62～296.91 mg/L,全果果浆发酵果酒总酚含量高于果汁发酵果酒;EC118、KI、KD全果果浆与果汁发酵果酒香气种类分别为25、30、28、22、23、24,共有香气14种,主要包括醇类、酯类和酸类等,三种酵母中KI、KD酵母发酵产香气能力较优,所得果酒酸度适宜、酒精度高,色泽澄清透亮,全果发酵总酚含量、香气种类均高于果汁发酵,KI酵母香气成分最多,且KI全果果浆发酵果酒总酚含量最高,所以选择KI全果果浆为香梨果酒的最佳菌种及发酵原料。     

Volatile aroma and sensory analysis of black raspberry wines fermented by different yeast strains

Robus coreanus Miquel is a small berry fruit used for Korean black raspberry (KBR) wine‐making. Twelve different yeast strains were investigated by laboratory‐scale fermentation to develop a wine with a high flavour quality. Volatile aroma compounds from the wines were analysed using headspace–solid phase microextraction–gas chromatography–mass spectrometry and sensory evaluation was performed to evaluate the flavour characteristics. The volatile aroma compounds that mostly contributed to the flavour of KBR wines were those related to fruity (esters) and floral (terpenes) aromas. Fifteen out of the 67 identified volatile compounds showed higher odour activity values than other compounds in the wines, and these compounds were considered as important contributors to the final aromas of the wine. Additionally, the KBR wine fermented by the M1 yeast strain had the highest sensory preference because of higher fruity and floral aroma characters compared with other wines. In addition to the M1 strain, the other yeast strains that produced favourable sensory characteristics included Enoferm CSM, Uvaferm VRB, Lalvin ICV GRE, Lalvin ICV Opale and LevureSeche Active. Of these strains, the M1 strain produced a particularly excellent black raspberry wine, and thus could be applied for further large‐scale production of black raspberry wines. It is also expected that this work will expedite research on the production of high‐quality black raspberry wines with beneficial physicochemical properties, functionality and good sensory characteristics. Copyright © 2015 The Institute of Brewing & Distilling