ABSTRACT
Lactic acid production using Kluyveromyces marxianus (IFO 288), Lactobacillus delbrueckii ssp. bulgaricus (ATCC 11842) and Lactobacillus helveticus (ATCC 15009) individually or as mixed culture on cheese whey in stirred or static fermentation conditions was evaluated. Lactic acid production, residual sugar and cell biomass were the main features examined. Increased lactic acid production was observed, when mixed cultures were used in comparison to individual ones. The highest lactic acid concentrations were achieved when K. marxianus yeast was combined with L. delbrueckii ssp. bulgaricus, and when all the strains were used revealing possible synergistic effects between the yeast and the two lactic acid bacteria. The same synergistic effects were further observed and verified when the mixed cultures were applied in sourdough fermentations, proving that the above microbiological system could be applied in the food fermentations where high lactic acid production is sought.
Subject(s)
Kluyveromyces/metabolism , Lactic Acid/biosynthesis , Lactobacillus delbrueckii/metabolism , Lactobacillus helveticus/metabolism , Cheese , Cooking , Culture Media , Ethanol/metabolism , Fermentation , Food Analysis , Food Handling/methods , Kluyveromyces/growth & development , Lactic Acid/analysis , Lactobacillus delbrueckii/growth & development , Lactobacillus helveticus/growth & developmentABSTRACT
Delignified cellulosic-supported biocatalyst, prepared by immobilization of kefir yeast on delignified cellulosic material (DCM), was found to be suitable for continuous, modified whey fermentation. The modified whey contained 1% raisin extract and molasses. Ethanol productivities ranged from 3.6 to 8.3 g L(-1)day(-1), whereas parameters such as ethanol concentration, residual sugars, and daily fermented whey productivity were acceptable for the production of potable alcohol and alcoholic drinks in industrial fermentations. The continuous fermentation bioreactor was operated for 39 days, stored for 18 days at 4 degrees C, and operated again for another 15 days without any diminution of the ethanol productivity. The concentrations of higher alcohols (propanol-1, isobutyl alcohol, and amyl alcohols) were low. The main volatile byproducts formed in the continuous process were similar to those observed in alcoholic beverages, and the fermented whey had a good aroma. The concentrations of higher alcohols were very low when compared to that of ethyl acetate, therefore resulting in a quality product. The possibility of using such a process for the production of potable alcohol or a novel, low-alcohol content drink is proposed.
Subject(s)
Cellulose , Fermentation , Milk Proteins/metabolism , Milk/microbiology , Yeasts/metabolism , Animals , Bioreactors , Ethanol/metabolism , Odorants , Volatilization , Whey ProteinsABSTRACT
Two alcohol resistant strains of Saccharomyces cerevisiae species were isolated from a Greek vineyard plantation. The strain AXAZ-1 gave a concentration of 17.6% v/v alcohol and AXAZ-2 16.5%, when musts from raisin and sultana grapes, respectively, were employed in alcoholic fermentations. They were found to be more alcohol tolerant and fermentative in the fermentation of molasse than the traditional baker's yeast. Specifically, using an initial [symbol: see text] Be density of 16 [symbol: see text] Be at the repeated batch fermentation process, in the first as well as fourth batch, the better AXAZ-1 gave final [symbol: see text] Be densities of 6.0 and 10.5 respectively, and the baker's yeast 11.6 and 14.5.
Subject(s)
Ethanol/metabolism , Ethanol/pharmacology , Molasses/microbiology , Saccharomyces cerevisiae/drug effects , Drug Resistance, Microbial , Fermentation , Fruit/metabolism , Saccharomyces cerevisiae/isolation & purification , Species Specificity , WineABSTRACT
Using gamma-alumina pellets, more than threefold increase of the ethanol productivity in the fermentation molasse has been obtained in the present work. Also, molasse fermentation in the presence of gamma-alumina gave 78.4 g/L ethanol, ethanol yield factor 0.44 g/g, and conversion 89.4% at initial sugar concentration (ISC) 179.5 g/L, compared to 53.9 g/L, 0.30 g/g and 62.7% in its absence, respectively. Furthermore, it was found that gamma-alumina reduces the activation energy Ea of fermentation. This inorganic material does not promote the fermentation of raisin extract.
Subject(s)
Aluminum Oxide , Ethanol/metabolism , Molasses , Saccharomyces cerevisiae/metabolism , Aluminum Oxide/pharmacology , Fermentation , Fructose/metabolism , Hydrogen-Ion Concentration , Kinetics , Sucrose/metabolism , TemperatureABSTRACT
A biocatalyst prepared by the immobilization of Saccharomyces cerevisiae on the surface of the mineral kissiris was used in the present study for continuous potable-alcohol production. An ethanol productivity (calculated on the basis of liquid volume) of 10.5 g/L/h was obtained at a 0.7/h dilution rate, 121 g/L sucrose content, and 29.6% conversion employing molasse as feed material. Glucose, raisin extracts, and molasse were successively used as feed materials without stopping the operation of the reactor for 6 mo. The ethanol productivity and yield remained constant during the operational-stability study of the reactor, carried out for 44 d. Biomass productivity, yield, and free-cell concentration in glucose, raisin extracts, and molasse were examined. Finally, a system with two continuous reactors joined successively was also studied in the present investigation.
