Evaluation of two brazilian native yeast strains (Pichia kudriavzevii) in craft beer

Beer production is an ancient biotechnological process and since yeast as discovered to be responsible for the transformation of barley wort into beer, studies have been carried out with the aim of understanding the behavior of these microorganisms. This work aimed to study the application of two strains of yeasts of the species Pichia kudriavzevii, isolated in the Brazilian Midwest for the production of craft beer and to analyze the occurrence of bioaromatization, with the production of volatile organic compounds (VOC) and to evaluate the sensory perception of the results with untrained end consumers through a quick sensory methodology called Check All That Apply (CATA). For this purpose, three batches of beer were produced and inoculated with commercial yeast (Saccharomyces cerevisiae, the control) and two strains of the same species, called Pichia kudriavzevii BB1 and Pichia kudriavzevii BB2. A total of 28 volatile organic compounds that differentiated the control of the Pichia BB1/BB2 group were detected, being 20 esters, 2 alcohols, 5 carboxylic acids and 1 hydrocarbon. There was no difference among the Pichia kudriavzevii BB1 and BB2 samples (p>0.05) in the sensory analysis using the CATA methodology. It was possible to distinguish two clusters between the tasters according to the habit of consuming craft beer, and those who consumed frequently, assigned a higher score in the hedonic test. It was concluded that Pichia kudriavzevii BB1 and BB2 influenced the beer bioaromatization, improving the acceptance test score with the tasters.

The Physical and Chemical Characteristics of Potato Doughnuts Using Semi-Liquid Local Yeast Derived from Myrrh of Red Fermented Palm Sap

Natural or local yeasts are microorganisms from natural ingredients obtained from fermentation without the need for artificial additives. The objectives of the present study were 1.) to evaluate the physical quality of potato doughnuts produced from the local yeast derived from residue of red fermented palm sap, 2) to obtain the best treatment from the use of local yeast in making doughnuts. In the fermentation process, yeast converts sugar and carbohydrates in the dough into carbon dioxide gas (CO2) and alcohol. Doughnuts are made from wheat flour, but the addition of potato paste can improve the texture so that it is softer and tender due to the interaction between gelatinized starch and gluten but can reduce its swelling power. The experiment was designed using a completely randomized design (CRD) with three treatments and five replications to produce 15 experimental units. The treatments were a) Control (commercial yeast); b) Wheat flour: potato paste: local yeast; 2:1:1; c) Wheat flour: potato paste: local yeast; 2:1:2 and d) Wheat flour: potato paste: local yeast; 2:1:3. The results showed that the best treatment formula was obtained in the treatment B (wheat flour: potato paste: local yeast; 2:1:1) with 20,6% moisture content, 2,09% protein content and 3,644 color value (very like), 3,800 taste value (very like) and texture/tenderness with a value of 1032,500.

Modulation of Welschriesling wine volatiles through the selection of yeast and lactic acid bacteria

Welschriesling is a variety common to Central and Eastern European wine-producing countries; however, its aromatic composition remains poorly understood. Our study aims to determine the volatile profile of Welschriesling by analysing varietal thiols, esters, higher alcohols and monoterpene alcohols in commercial wines. In addition, the selection of commercial yeast starters and lactic acid bacteria (LAB) was used to modulate Welschriesling wine volatile composition. Both the selection of yeast and LAB had a significant impact on the compositional parameters of the wines. Yeast starter Uvaferm 228 (UVF228) was the most effective in terms of 3-mercaptohexan-1-ol (3MH) and 3-mercaptohexyl acetate (3MHA) production. For the ethyl esters of fatty acids (EEFAs), higher alcohol acetates (HAAs) and higher alcohols (HAs), no common inter-group behaviour could be observed based on yeast selection, however, as a group, EEFAs and HAs were highest in wines fermented with UVF228.Malolactic fermentation (MLF) significantly influenced varietal thiols, irrespective of the LAB strain used. Concentrations of 3MH significantly increased with MLF, 4-mercapto-4-methyl-pentan-2-one (4MMP) concentrations decreased, while 3MHA concentrations remained unaltered. This study showed the specific influence of yeast and LAB strain on selected volatile compounds. MLF appeared to be a promising tool to boost the presence of 3MH in wines, however, the results need further confirmation across a range of fermentation conditions and strain selections.

Influence of Autochthonous and Commercial Yeast Strains on Fermentation and Quality of Wines Produced from Vranec and Cabernet Sauvignon Grape Varieties from Tikveš Wine-Growing Region, Republic of North Macedonia

Two autochthonous yeast strains called F-8 and F-78 (isolated and selected from the Tikveš wine-producing region) were inoculated in wine musts from Vranec and Cabernet Sauvignon grape varieties. The fermentation process and quality of the produced wines were compared to the wines produced from the same grape varieties, but with a commercial yeast strain (D-80). The fermentation process was undertaken at 23–25 °C for 16 days. The highest alcohol content was detected in Vranec and Cabernet Sauvignon wines fermented with autochthonous F-8 yeast strain. Conversely, Vranec wine fermented by the F-78 yeast strain contained the lowest alcohol content (14.11%). The low sugar amount (2–3 g/L) in both grape varieties is indicated the production of dry wines. The total amount of phenolic compounds was significantly higher in Vranec wines. Unlike the alcohol content, Vranec wine produced by commercial yeast strain D-80 indicated the highest concentration of total phenolic compounds (1450 mg/L) and total anthocyanins (572 mg/L), while the lowest concentrations were observed in wine fermented by autochthonous yeast strain F-78 (1612 mg/L and 470 mg/L, respectively). The maximum color intensity was measured in the Vranec wine fermented by autochthonous yeast strain F-8, while wines from Cabernet Sauvignon grape variety fermented with the same yeast strain F-8 and commercial yeast strain D-80 had comparable values in terms of color intensity.

The Evaluation of the Addition of Commercial Yeast with β -Glucan Content in Feed on the Immunity of Snakehead Fish Channa striata Infected by Aeromonas hydrophila Bacteria

Snakehead fish Channa striata is a high commercial freshwater fish commodity. It has the potential as a pharmaceutical ingredient. Intensive snakehead fish cultivation starts to experience a problem, namely Motile Aeromonas Septicemia (MAS) caused by Aeromonas hydrophila. The purpose of this study is to evaluate the effect of the addition of commercial yeast in feed to improve snakehead fish immunity. This study was designed with a completely randomized design (CRD) with 5 treatments with 3 replications (reared in the net) and 6 treatments with 3 replications (reared in the aquarium). The treatments were K (feed without yeast), F5 (feed with the addition of 5 g/kg of cake yeast), R3 (feed with the addition of 3 g/kg of tempeh yeast, R5(feed with the addition of 5 g/kgof tempeh yeast), and R7 (feed with the addition of 7 g/kg of tempeh yeast). The results show that the survival rate after 30 days is 88.89- 92.22%. The best treatment after A. hydrophila infection was found in fish fed with 3 g/kg oftempehyeast with a survival rate of 56.67%, total erythrocytes of 4.07x 106 mm-3 cells, hemoglobin of 7.40 g% of total leukocytes 4.97x 104 mm-3 cells and phagocytic activity of 33.67. In conclusion, the addition of tempeh yeast at a dose of 3 g/kg could be used as an alternative to prevent the effect of A. hydrophila pathogen infection in snakehead fish.

Influence of Different Vinification Techniques on Volatile Compounds and the Aromatic Profile of Palomino Fino Wines

The aim of this study was to evaluate the influence of vinification techniques on volatile compounds and sensory profiles in young Palomino fino white wines. Four winemaking techniques (pellicular maceration, supra-extraction and use of commercial yeast strains and of β-glycosidase enzymes) were implemented to enhance the aromatic quality of wines elaborated from this neutral variety of grape. Volatile compound content, aromatic profile (OAVs) and sensorial analysis were determined. The results showed that all the vinification techniques studied led to an increase in volatile compounds compared to the control wine. Likewise, an influence of the vineyard and must extraction method on these compounds was observed. However, the greatest changes in aroma activity and sensory profile were a result of the pellicular maceration and supra-extraction techniques. The latter was differentiated by the highest content of terpenes and, consequently, the highest odour activity values of floral series. In addition, the supra-extraction was a very selective technique since it extracted terpenes and aromatic precursors, but not the acids responsible for the fatty characteristic, such as octanoic acid. In terms of sensory profile, the supra-extraction technique improved the intensity of the Palomino fino white wine and its aromatic quality with a previously not-determined floral character.

Production of functional beer with the addition of probiotic: Saccharomyces boulardii

Industries have been investing in the development of functional products, such as the ones produced with probiotic microorganisms. The aim of this study was to develop a Pilsen-style beer with functional properties through the addition of the Saccharomyces boulardii probiotic. The beer was fermented with low-fermentation commercial yeast. The probiotic culture was added next, evaluating its probiotic potential. Microbiological, sensorial and physicochemical aspects were evaluated in the obtained products. The S. boulardii strain presented probiotic viability after the confirmation of the resistance to acid, bile salts and ethyl alcohol tests, maintaining superior levels of colony-forming to the indicated by the legislation during the 28 days storage. The beer with probiotic addition has not differed sensorially from the commercial beer concerning the aroma, flavor, general appearance and color. The results of sensorial, physicochemical and microbiological analysis showed the viability of the production of probiotic beer with the addition of S. boulardii.

Influence of L. thermotolerans and S. cerevisiae Commercial Yeast Sequential Inoculation on Aroma Composition of Red Wines (Cv Trnjak, Babic, Blatina and Frankovka)

Even though Saccharomyces cerevisiae starter cultures are still largely used nowadays, the non-Saccharomyces contribution is re-evaluated, showing positive enological characteristics. Among them, Lachancea thermotolerans is one of the key yeast species that are desired for their contribution to wine sensory characteristics. The main goal of this work was to explore the impact of L. thermotolerans commercial yeast strain used in sequential inoculation with S. cerevisiae commercial yeast on the main enological parameters and volatile aroma profile of Trnjak, Babić, Blatina, and Frankovka red wines and compare it with wines produced by the use of S. cerevisiae commercial yeast strain. In all sequential fermented wines, lactic acid concentrations were significantly higher, ranging from 0.20 mg/L in Trnjak up to 0.92 mg/L in Frankovka wines, while reducing alcohol levels from 0.1% v/v in Trnjak up to 0.9% v/v in Frankovka wines. Among volatile compounds, a significant increase of ethyl lactate and isobutyl acetate, geraniol, and geranyl acetate was detected in all wines made by use of L. thermotolerans. In Babić wines, the strongest influence of sequential fermentation was connected with higher total terpenes and total ester concentrations, while Trnjak sequentially fermented wines stood up with higher total aldehyde, volatile phenol, and total lactone concentrations. Control wines, regardless of variety, stood up with higher concentrations of total higher alcohols, especially isoamyl alcohol. The present work contributed to a better understanding of the fermentation possibilities of selected non-Saccharomyces strains in the overall red wine quality modeling.