The occurrence of malolactic fermentation in brandy base wine and its influence on brandy quality

AIMS: In this study we determined the extent to which lactic acid bacteria (LAB) occurred in brandy base wines, their ability to catalyse the malolactic fermentation (MLF) and the effect of MLF on the quality of the base wine and the brandy distillate. METHODS AND RESULTS: Lactic acid bacteria were isolated and enumerated from grape juice, experimental and commercially produced brandy base wines. Spontaneous MLF occurred in approximately 50% of the commercial base wines. The occurrence of MLF had an influence on the quality of the base wines and the resulting distillates. In samples where MLF occurred there was a loss of fruitiness and in the intensity of aroma. Volatile compounds like iso-amyl acetate, ethyl acetate, ethyl caproate, 2-phenethyl acetate and hexyl acetate decreased in samples having undergone MLF, while ethyl lactate, acetic acid and diethyl succinate increased in the same samples. CONCLUSIONS: Spontaneous malolactic fermentation does occur in commercial brandy base wines and it has an influence on base wine and brandy quality. SIGNIFICANCE AND IMPACT OF THE STUDY: This study showed that MLF influences the quality of the base wine and the resulting distillate and with this in mind commercial base wine producers should be able to produce brandy of higher quality.     

Immobilized enzymes from Geotrichum spp. improve wine quality

Higher alcohols are the byproducts of yeasts in alcohol fermentation and are harmful to human health at high concentrations. In this study, immobilized crude enzymes extracted from Geotrichum spp. strains S12 and S13 were separately employed to treat red wine, then GC and GC-MS analyses were used to determine the profiles of volatile compounds in untreated and treated wine samples. Immobilized enzymes from S13 (SA-S13E) were more active in decreasing higher alcohols than enzymes from S12. Conditions for preparing SA-S13E were optimized, and best results were obtained at a sodium alginate concentration of 35 g/L, calcium chloride of 20 g/L, and crude enzyme dosage of 3 mL. Treatment with SA-S13E significantly increased the ester content and sensory quality of wine. After being reused three times, SA-S13E still exhibited approximately 80% activity towards 1-propanol, isobutanol, and hexanol and had certain activity even after 3 months storage at −20 °C, indicating high stability in application and storage and thus showing potential in wine processing.     

Impact of fermentation rate changes on potential hydrogen sulfide concentrations in wine

The correlation between alcoholic fermentation rate, measured as carbon dioxide (CO2) evolution, and the rate of hydrogen sulfide (H2S) formation during wine production was investigated. Both rates and the resulting concentration peaks in fermentor headspace H2S were directly impacted by yeast assimilable nitrogenous compounds in the grape juice. A series of model fermentations was conducted in temperature-controlled and stirred fermentors using a complex model juice with defined concentrations of ammonium ions and/or amino acids. The fermentation rate was measured indirectly by noting the weight loss of the fermentor; H2S was quantitatively trapped in realtime using a pre-calibrated H2S detection tube which was inserted into a fermentor gas relief port. Evolution rates for CO2 and H2S as well as the relative ratios between them were calculated. These fermentations confirmed that total sulfide formation was strongly yeast strain-dependent, and high concentrations of yeast assimilable nitrogen did not necessarily protect against elevated H2S formation. High initial concentrations of ammonium ions via addition of diammonium phosphate (DAP) caused a higher evolution of H2S when compared with a non-supplemented but nondeficient juice. It was observed that the excess availability of a certain yeast assimilable amino acid, arginine, could result in a more sustained CO2 production rate throughout the wine fermentation. The contribution of yeast assimilable amino acids from conventional commercial yeast foods to lowering of the H2S formation was marginal.     

The influence of climatic variability on the quality of wine

In this paper, the quality of the wine from the Dão (Viseu) region of Portugal is examined and relationships between wine quality and climatic variability are obtained using spectral and correlation analysis to determine the structure of the temporal variations. The spectra of the series of quality of wine values show statistically significant oscillations coherent with those found in the series of teleconnection indices. The series cover a period of 33 years. A significant correlation was obtained between wine quality and minimum air temperature in May, December and total precipitation in April. The teleconnection circulation indices are used to provide some physical insight into the most significant oscillating components of the climatic and the wine quality series. We found significant and positive correlations between the quality of the wine and the Southern Oscillation Index (SOI) of August and negative with the SOI of January and with the North Atlantic Oscillation of April. Wine quality and climatic series can be predicted using statistical models depending on significant oscillations.     

Cholinesterase inhibitory potential of different Alternaria spp. and their phylogenetic relationships

Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibitors are used for the treatment of various disorders related to decline in acetylcholine levels in the brain by inhibiting the activity of the neurotransmitter AChE. The present study reports the potential of endophytic Alternaria spp. for their potential to produce cholinesterase inhibitors active against both acetylcholine and butyrylcholine. Twenty-nine isolates belonging to Alternaria spp. were isolated from different plants and screened. Variation with respect to inhibitor production was observed in different isolates. Out of 29 cultures screened, good cholinesterase (both AChE and BChE) inhibitory activity in range of 70–85% was observed in three isolates, whereas three showed only AChE inhibition. No correlation was observed in AChE and BChE inhibitor production. TLC bioautography for the inhibitor in the selected cultures evinced different Rf values of inhibitors indicating different nature of the compounds produced. In order to analyze evolutionary relationships between producer and non-producer strains, phylogenetic analysis of six producer and five non-producer strains was carried out using amplified ITS-I-5.8SrDNA-ITS-II region. Phylogenetic analysis revealed majority of the non-producer strains to be present on different clades indicating different evolutionary origins. The dual cholinesterase inhibitory activity and the diversity in the inhibitors produced by different isolates could prove to be novel sources of pharmaceutical as well as agriculturally important biomolecules after purification and characterization.     

Oils as adhesives for seed inoculation and their influence on the survival of Rhizobium spp. and Bradyrhizobium spp. on inoculated seeds

Mineral oil, peanut oil and soybean oil were compared with water and gum arabic for their suitability as adhesives for seed inoculation with peat inoculants. Inoculated seeds were stored at 4, 28 and 34°C, and sampled after 1, 3 and 9 days to determine the survival of rhizobia. Germination and nodulation tests were performed on the inoculated seeds. Results showed that oils were suitable adhesives for peat inoculants. Although the oils initially bound less inoculant to the seed, the number of surviving rhizobia was similar to that obtained by the gum arabic treatment after storage at 28 and 34°C for 3 and 9 days. An interesting finding of this experiment was that peanut and soybean oils were superior to gum arabic in supporting significantly higher numbers of chickpea rhizobia at 34°C. Inoculated seeds tested for germination and nodulation showed no adverse effects from the oil treatments. Oils hold good potential as adhesives for seed application in inoculation technology.H.J. Hoben and P. Somasegaran are with the NIFTAL Project, University of Hawaii, 1000 Holomua Avenue, Paia, HI 96779-9744, USA. Nwe Nwe Aung is with the Institute of Agriculture, Yezin, Pyinmana, Burma. Ui-Gum Kang is with the Yeongnam Crop Experiment Station, Rural Development Administration, P.O. Box 6, Milyang, Korea.     

三株散囊菌属真菌的茶叶液态发酵与其成分分析

散囊菌属真菌(Eurotium spp.)又称“金花菌”,能在六堡茶表面生长出金黄色的子囊果而得名,是一类对发酵茶叶的品质有积极影响的真菌。本研究前期从广西梧州六堡茶中筛选到的三株散囊菌属真菌Aspergillus chevalieri E2(简称E2),Aspergillus chevalieri E3(简称E3)与Aspergillus cristatus E6(简称E6),将菌株接种于自制液体茶粉培养基中培养,检测发酵液中产生的色素物质;测定发酵液中纤维素酶、果胶酶、淀粉酶的酶活力、总糖和还原糖糖含量、氨基酸含量、总抗氧化能力、自由基清除能力和茶多酚含量。结果表明:三株真菌在液体茶粉培养基中生长良好,E3生长尤其迅速。在8 d的培养期限内,E2、E3和E6的最高果胶酶活力分别为2.52、3.44和5.15 U/mL;最高纤维素酶活力分别为0.57、0.82和1.10 U/mL;最高淀粉酶活力分别为0.31、0.35和0.49 U/mL。三株真菌的发酵后培养液中还原糖含量大幅增加,增幅分别达到131.70%、627.02%和459.12%;总糖含量同样呈上升趋势,增幅分别达到6.84%、35.25%和2.07%;E2与E3的氨基酸含量分别下降了17.43%与32.68%,E6则上升了0.52%;E3的总抗氧化活性提升最大,达65.87%;DPPH·自由基清除能力提升最大的是E2,达128.33%;茶多酚含量都显著提升,增幅分别为50.85%、51.58%和53.06%。本研究对改善六堡茶的品质及茶叶的发酵的研究有一定意义和参考价值。     

Ethanol fermentation and potential.

Ethyl alcohol is one of the United States and world's major chemicals. Beverage alcohol in the United States must be prepared from cereal grains or other natural products. The U.S. industrial alcohol market has remained relatively stable for several years at approximately 300 million gallons annually. Most of this has been produced synthetically from petroleum raw material (gas and oil). These raw materials are experiencing major price increases and are in short supply. The production of ethyl alcohol from cereal grains and cellulosic raw materials by fermentation is technically feasible and has been proven. Alcohol produced from all such materials is equal to synthetic alcohol in quality and performance. Competitive economics have controlled the basic raw materials used. The major potential new ethyl alcohol market is as a component of automobile fuels. A 10% alcohol-gasoline blend in the United States would annually require over 10 billion gallons of anhydrous alcohol. Use of alcohol for this purpose is technically feasible. However, alcohol has not been economically competitive to date.     

Technological characteristics of yeast strains and their potential as starter adjuncts in Greek-style black olive fermentation

The technological properties of Debaryomyces hansenii (15 strains) and Torulaspora delbrueckii (32 strains) isolated from Greek-style black olives under conditions typical for black olive fermentation were studied. Furthermore, the killer character of the strains was assessed as well as their antimicrobial action against food-borne pathogens. All strains could grow at 15°C and low pH (2.5), whereas the majority of the strains were able to grow at 10% (w/v) NaCl, assimilated d-galacturonic acid, and showed lipolytic activity. Only 33% of D. hansenii and 9% of T. delbrueckii strains could hydrolyse 1% (w/v) oleuropein. A large majority of the strains tolerated 0.3% (w/v) bile salts, which in correlation with acid resistance indicates probiotic potential. Cross-reactions between culture filtrates of D. hansenii and T. delbrueckii and 56 yeast strains isolated during spontaneous Greek-style black olive fermentation were conducted. Focusing on their lytic activity, 17 mycogenic strains were selected. Culture filtrates of the mycogenic strains inhibited strains of L. monocytogenes, B. cereus and S. typhimurium. The active substance was heat resistant (stable after heating at 100°C for 10 min) as well as stable over a pH range from 4.0 to 6.5. The possible inhibition of undesirable yeast contaminants and food-borne pathogens in situ on fermented olives as well as the probiotic potential of strains used as starter adjuncts would contribute to the improvement of quality of the fermented product.     

Timing of malolactic fermentation inoculation in Shiraz grape must and wine: influence on chemical composition

Malolactic fermentation (MLF) is an integral step in red winemaking, which in addition to deacidifying wine can also influence the composition of volatile fermentation-derived compounds with concomitant affects on wine sensory properties. Long-established winemaking protocols for MLF induction generally involve inoculation of bacteria starter cultures post alcoholic fermentation, however, more recently there has been a trend to introduce bacteria earlier in the fermentation process. For the first time, this study shows the impact of bacterial inoculation on wine quality parameters that define red wine, including wine colour and phenolics, and volatile fermentation-derived compounds. This study investigates the effects of inoculating Shiraz grape must with malolactic bacteria at various stages of alcoholic fermentation [beginning of alcoholic fermentation (co-inoculation, with yeast), mid-alcoholic fermentation, at pressing and post alcoholic fermentation] on the kinetics of MLF and wine chemical composition. Co-inoculation greatly reduced the overall fermentation time by up to 6 weeks, the rate of alcoholic fermentation was not affected by the presence of bacteria and the fermentation-derived wine volatiles profile was distinct from wines produced where bacteria were inoculated late or post alcoholic fermentation. An overall slight decrease in wine colour density observed following MLF was not influenced by the MLF inoculation regime. However, there were differences in anthocyanin and pigmented polymer composition, with co-inoculation exhibiting the most distinct profile. Differences in yeast and bacteria metabolism at various stages in fermentation are proposed as the drivers for differences in volatile chemical composition. This study demonstrates, with an in-depth analysis, that co-inoculation of yeast and bacteria in wine fermentation results in shorter total vinification time and produces sound wines, thus providing the opportunity to stabilise wines more rapidly than traditional inoculation regimes permit and thereby reducing potential for microbial spoilage.     

感染瓜实蝇的曲霉菌及其生物学特性

从海南自然发病死亡的瓜实蝇上分离获得2株高毒力的真菌BC-D1和BC-212,经形态学和ITS序列鉴定结果表明, BC-D1为黄曲霉Aspergillus flavus,BC-212为溜曲霉Aspergillus tamarii。室内毒力测定结果发现：菌株BC-D1和BC-212对瓜实蝇成虫均有很高毒力,而对卵、幼虫及蛹的毒力较低。接种8d后成虫的平均死亡率分别为73.5%和85.1%,卵、幼虫及蛹的死亡率均低于50%。两株菌对黄粉虫、斜纹夜蛾及蚜虫的致病率均很低。生物学特性测定,两菌株具有生长速度快、产孢量大的特性,最适合生长的温度范围为30-35℃;在不同营养成分的培养基上,菌株生长速率、产孢量及菌落颜色存在较大差异。     

Performance of potential European biological control agents of Vincetoxicum spp. with notes on their distribution

Exploratory surveys were conducted in Europe to locate potential biological control agents of Vincetoxicum nigrum and Vincetoxicum rossicum and to collect known specialist herbivores of Vincetoxicum hirundinaria (Abrostola asclepiadis, Chrysolina a. asclepiadis, Eumolpus asclepiadeus and Euphranta connexa). Development of the most abundant herbivores found attacking leaves, roots, and developing seeds was evaluated in the laboratory on three Vincetoxicum spp. Field surveys revealed that the highest diversity of herbivores was associated with the abundant and widespread V. hirundinaria. No new herbivores were reported from V. hirundinaria or V. nigrum, but the leaf‐feeding noctuid Hypena opulenta was recorded for the first time attacking V. rossicum and V. scandens in Ukraine. Based upon larval survival and development and adult fecundity, the leaf feeders A. asclepiadis, C. a. asclepiadis, and H. opulenta, perform better on V. nigrum and V. rossicum than on V. hirundinaria. Larval performance of the root feeder E. asclepiadeus followed a similar pattern, but adult fecundity of this insect did not vary among host plant species. Immature development time of the pre‐dispersal seed feeder E. connexa is similar among hosts, but larvae grow larger on V. nigrum and V. hirundinaria than on V. rossicum. All herbivores are promising biological control agents of Vincetoxicum in North America and we have prioritized host range testing with H. opulenta and E. asclepiadeus.     

Isolation and functional characteristics of the fungus Hypoxylon spp. Sj18 with biocontrol potential

A fungus with biocontrol potential was isolated from the roots of hickory trees. The strain named sj18 was classified as a member of the genus Hypoxylon (Hypoxylaceae) after multigene phylogenetic analysis (beta-tubulin gene, internal transcribed spacer, 28S large subunit ribosomal RNA gene, and RNA polymerase II subunit gene). The strain grew well on a PDA with an optimum temperature range between 32 and 34 °C. The fungus had obvious inhibitory effects on Botryosphaeria dothidea, Colletotrichum gloeosporioides, and Gibberella moniliformis in fumigation experiments on solid agar plates. In an inoculation experiment of Chinese cabbage, the fungus was also found to have an obvious repellent effect on cabbage caterpillars. In vitro experiments on Petri dishes showed that the fermentation broth of the sj18 strain could kill 100% of Bursaphelenchus xylophilus within 8 h even if the fermentation broth was diluted 8 times. The inoculation test of Arabidopsis thaliana showed that the fungus could promote the lateral root formation of plants and significantly increase their aboveground biomass. Through the analysis of solid phase microextraction (SPME), it was found that the main volatile components of the fermentation products were azulene 65.39% (61.77% + 3.62%), caryophyllene 7.41%, and eucalyptol 6.83% according to the peak area ratio. Therefore, sj18 can be used as a candidate for the further research and development of biocontrol agents.     

Interactions between Torulaspora delbrueckii and Saccharomyces cerevisiae in wine fermentation: influence of inoculation and nitrogen content

Alcoholic fermentation by an oenological strain of Torulaspora delbrueckii in association with an oenological strain of Saccharomyces cerevisiae was studied in mixed and sequential cultures. Experiments were performed in a synthetic grape must medium in a membrane bioreactor, a special tool designed to study indirect interactions between microorganisms. Results showed that the S. cerevisiae strain had a negative impact on the T. delbrueckii strain, leading to a viability decrease as soon as S. cerevisiae was inoculated. Even for high inoculation of T. delbrueckii (more than 20× S. cerevisiae) in mixed cultures, T. delbrueckii growth was inhibited. Substrate competition and cell-to-cell contact mechanism could be eliminated as explanations of the observed interaction, which was probably an inhibition by a metabolite produced by S. cerevisiae. S. cerevisiae should be inoculated 48 h after T. delbrueckii in order to ensure the growth of T. delbrueckii and consequently a decrease of volatile acidity and a higher isoamyl acetate production. In this case, in a medium with a high concentration of assimilable nitrogen (324 mg L^?1), S. cerevisiae growth was not affected by T. delbrueckii. But in a sequential fermentation in a medium containing 176 mg L^?1 initial assimilable nitrogen, S. cerevisiae was not able to develop because of nitrogen exhaustion by T. delbrueckii growth during the first 48 h, leading to sluggish fermentation.     

The potential of positively-charged cellulose sponge for malolactic fermentation of wine, using Oenococcus oeni

Malolactic fermentation (MLF) is a secondary bioconversion developed in some wines involving malic acid decarboxylation. The induction of MLF in wine by cultures of free and immobilized Oenococcus oeni cells was investigated. This work reports on the effect of surface charges in the immobilization material, a recently described fibrous sponge, as well as the pH and the composition of the media where cells are suspended. A chemical treatment provided positive charge to the sponges (DE or DEAE) and gave the highest cell loadings and subsequent resistance to removal. Preculture media to grow the malolactic bacteria before the immobilization procedure were also evaluated. We have established favorable conditions for growth (Medium of Preculture), suspension solution (Tartrate-Phosphate Buffer), suspension pH (3.5-5.5) and immobilization matrix (DE or DEAE cellulose sponge) to induce MLF in red wine. The use of a semi-continuous system permitted a high-efficiency malic acid conversion by 2 x 10(9) cfu sponge(-)(1) in at least four subsequent batch fermentations.