Utilization of post-fermentation yeasts for yeast extract production by autolysis: the effect of yeast strain and saponin fromQuillaja saponaria (original) (raw)
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Journal of the Institute of Brewing
Spent yeasts, a co-product from fermentation processes, are a source for unconvential autolysis processes. In this study, five post-fermentation yeast strains that are often used in fermentation processes were used: Saccharomyces cerevisiae Ethanol Red (Lessafre), Kluyveromyces marxianus LOCK 0026, K. marxianus NCYC 179, Scheffersomyces stipitis NCYC 1541 and Pichia angusta NCYC 495. Autolysis was conducted at 50°C for 48 hours in the presence of saponins from Quillaja saponaria. The concentrations of proteins and free amino acids in the yeast autolysates were evaluated using IR spectroscopy and chromatography. The lysates were found to be good sources of essential amino acids, which constituted between 29.3% (S. cerevisiae) and 40.7% (K. marxianus LOCK 0026) of the amino acid pools. The largest pools of free amino acids were found in autolysates of S. cerevisiae Ethanol Red (44.9 g/L) and P. angusta NCYC 495 (40.53 g/L). Saponin can be used as an auxiliary or alternative to conventional methods of cell lysis, especially since Q. saponaria extracts are approved for use in foods and could have significant health benefits. The usability of five post-fermentation yeast strains as a source of valuable nitrogen compounds in unconventional salt-free lysates was demonstrated for the first time in the present study.
Elucidation of the Role of Nitrogenous Wort Components in Yeast Fermentation
Journal of the Institute of Brewing, 2007
The Free Amino Nitrogen (FAN) content of wort prescribes efficient yeast cell growth and fermentation performance. FAN consists of the individual amino acids, small peptides and ammonia ions formed during malting, the relative amounts of which vary. In this paper, the individual constituents of FAN were dissected and their effect on both ale and lager fermentations determined. The patterns of amino acid and small peptide uptake and the changes in extracellular protease activity revealed the dynamic environment that develops during fermentation. Lysine and methionine, previously identified as key amino acids in wort fermentation, were investigated further.
2017
The deficiency of protein in human food and animal feed is well recognized due to the rapid growth of population. It is therefore, important to increase protein production by utilizing all the available ways and means. In the light of this, an attempt was made in this study by selecting Candida utilis NOY1. This yeast was used to determine the optimum concentration of different minerals salts and nitrogen source on growth. This study aimed at improving the medium composition for efficient and high yield yeast biomass production using tubers wastes. Proximate analysis of the biomass revealed that the protein and nucleic acid content were 54.8 and 4.6%, respectively. Amino acid profiles were found to be comparable to those of the Food and Agriculture Organization of the United Nations reference. This study shows that tubers wastes supplemented with peptone and yeast extract could be used as a good production medium for large scale production of yeast biomass and C. utilis NOY1 possess...
Food and Bioproducts Processing, 2008
This study aimed to determine the optimum autolysis conditions for the production of yeast extract, which is used to give a meaty flavor to food products and to increase their nutritional value. Autolysis was induced by incubating baker's yeast cell suspensions at different temperatures (45, 50, 55, and 60 °C) with a reaction time ranging from 8 to 72 h. Content and yield of total solids, α-amino nitrogen (α-AN), and protein were determined. Yeast extract powder was obtained by drying liquid yeast extract in a pilot scale spray drier. Sensory analysis was performed by adding the yeast extract powder at different concentrations (0.5%, 1.0%, 1.5%, and 2.0%) to vegetable soup. Optimum temperature and time for the production of yeast extract was 50 °C for 24 h, based on α-AN content, which was 3.7%. Furthermore, under the same conditions, protein content was 52.5% and total solids content was 1.98%. According to sensory analysis, the sample with 0.5% yeast extract powder and the control had the highest overall acceptance. According to variance analysis, differences between total solids, α-AN, and protein content determined at 4 different temperatures, and interactions between duration and temperature were statistically significant (P < 0.01).
Production and evaluation of a yeast utilizing an industrial waste
Biological Wastes, 1990
Pichia pinus was grown in a semi-continuous process on mango-peel extract medium. The yield was 8 g/litre after 12 h at the end of the logarithmic phase. The biomass ofPichia pinus contained53" 7% protein. Amino acid analyses of the protein revealed the presence of all amino acids in substantial amounts except for those containing sulphur, which were the limiting amino acids. When fed to rats the protein biomass exhibited good nutritional values (protein efficiency ratio, 2"77 +_ 0"126; apparent digestibility, 71"54 +_ 1"02) as compared to the casein diet (protein efficiency ratio, 2.913 +_ 0.127; apparent digestibility, 90"156 +_ 0"64). A lkaline phosphatase levels were insignificantly different from the control during the experimental period (21, 28, 35 and 42 feeding days). The transaminases, 7-glutamyl tranaferase activities and creatinine levels in the serum were significantly varied at the 35th and 42nd feeding days. The glutamate oxaloacetate transaminase, urea and uric acid levels in serum were significantly increased only after 35 feeding days. No histological changes were observed in either liver or kidney tissues.
Fermentation, 2021
Organic nitrogen plays a significant role in the fermentation performance and production of esters and higher alcohols. This study assessed the use of yeast protein hydrolysate (YPH) as a nitrogen source for grape must fermentation. In this study, we prepared an enzymatic protein hydrolysate using yeasts recovered from a previous fermentation of wine. Three treatments were performed. DAP supplementation was used as a control, while two YPH treatments were used. Low (LDH) and high degrees of hydrolysis (HDH), 3.5% and 10%, respectively, were chosen. Gas chromatography and principal component analysis indicated a significant positive influence of YPH-supplementations on the production of esters and higher alcohols. Significantly high concentrations of 3-methyl-1-penthanol, isoamyl alcohol, isobutanol, and 2-phenylethanol were observed. Significant odorant activity was obtained for 3-methyl-1-pentanol and ethyl-2-hexenoate. The use of YPH as nitrogen supplementation is justified as a r...
ENHANCEMENT OF AMINO ACID PRODUCTION BY TWO-STEP AUTOLYSIS OF SPENT BREWER'S YEAST
Chemical Engineering Communications, 2011
A two-step autolysis process was proposed to enhance amino acid production from spent brewer's yeast. The technique was developed based on comparative study of the dynamics of production and release of proteins and amino acids during the autolysis of a concentrated suspension (22 wt.%) and a dilute yeast cell suspension (11.25 wt.%). The results suggest that, in the concentrated yeast suspension, proteins are more effectively broken down into amino acids, but the product release rate was lower due to a lower concentration gradient across the cell membrane. Thus, a two-step process, in which a high protein conversion occurred in a concentrated cell suspension during the first 13 h period, followed by a 26 h autolysis process within a dilute cell suspension, provided a higher overall yield of amino acids compared than the single-step process. The two-step process was found to result in a 25% higher amino acid yield with a weight fraction increase from 0.4 to 0.5 g/g dry wt. Other than these findings, the effect of adding NaCl to the suspension during autolysis was also investigated. It was found that, for the autolysis conditions employed in this study, the addition of NaCl did not significantly affect the production of protein but inhibited the production of amino acids.
Effect of the complementation of nitrogen substrates on the biomass yields of yeast cultures
In Saccharomyces cerevisiae cultures in a glucose and protein hydrolysate media, the addition of yeast extract or salts and/or vitamins can induce a dramatic increase of biomass yields. The role of such compounds is a critical point in comparative works on the evaluation of protein hydrolysates, as it can modify the ranking. Such results also suggest that differences on biomass yields observed on some protein hydrolysates can be due to the non protein fraction.
FEMS Yeast Research, 2012
Nitrogen limitation is one of the most common causes for stuck or sluggish fermentation. A broad range of values have been reported as the minimum nitrogen concentration necessary for the completion of alcoholic fermentation. We have analyzed the minimum nitrogen concentration required to yield the maximum biomass (nitrogen reference value) using a microwell plate reader to monitor fermentation with different nitrogen sources and sugar concentrations. The biomass yield was dependent on the amount of available nitrogen, the nature of nitrogen source, and the sugar concentration in the medium. Nevertheless, achieving the maximum biomass was not sufficient to ensure the completion of the alcoholic fermentation, because the fermentation of 280 g sugar L À1 stuck, regardless of the nature and concentration of nitrogen source. However, a mixture of five amino acids (Leu, Ile, Val, Phe and Thr) as the nitrogen source allowed for maximum sugar consumption. Analysis of cell vitality by impedance showed a significant improvement in the vitality for cells fermenting using this amino acid combination.
Spent Yeast Valorization for Food Applications: Effect of Different Extraction Methodologies
Foods
Over the years, synthetic biology has been growing with the use of engineered yeast strains for the production of sustainable ingredients to meet global healthcare, agriculture, manufacturing and environmental challenges. However, as seen from the brewing industry perspective, these processes generate a substantial amount of spent yeast that contains high nutritional value related to its high protein content, showing its potential to be used as an alternative protein source. Taking into account the rising demand for protein because of the growth in the global population, the present study aims to produce peptide-rich extracts by different potentially scalable and sustainable methodologies in a circular economy approach for the food and nutraceutical industries. The results demonstrated that extraction from genetically modified strains allowed the production of extracts with an excellent nutritional profile and low molecular weight peptides. Furthermore, autolysis was shown to be a p...