Biomedical subjects

A Bekatorou

Publications and source records attributed to A Bekatorou.

4 recordsLinked to original sources

PubMed2006

Use of Saccharomyces cerevisiae cells immobilized on orange peel as biocatalyst for alcoholic fermentation.

A biocatalyst was prepared by immobilizing a commercial Saccharomyces cerevisiae strain (baker's yeast) on orange peel pieces for use in alcoholic fermentation and for fermented food applications. Cell immobilization was shown by electron microscopy and by the efficiency of the immobilized biocatalyst for alcoholic fermentation of various carbohydrate substrates (glucose, molasses, raisin extracts) and at various temperatures (30-15 degrees C). Fermentation times in all cases were low (5-15 h) and ethanol productivities were high (av. 150.6 g/ld) showing good operational stability of the biocatalyst and suitability for commercial applications. Reasonable amounts of volatile by-products were produced at all the temperatures studied, revealing potential application of the proposed biocatalyst in fermented food applications, to improve productivities and quality.

Alcohols↗

PubMed2005

Kefir yeast technology: scale-up in SCP production using milk whey.

A three-step process to scale-up kefir biomass production at a semi-industrial scale employing whey is reported. Aerobic fermentations were initially performed at laboratory scales, in 1.5- and 4-L bioreactors, yielding 79 g/L final kefir biomass (0.89 g/g of lactose utilized), in 7 h of fermentation time. The use of whey as carbon source even in solid cultures led to the formation of a granular biomass. These results encouraged scale-up at a semi-industrial-scale pilot plant employing 100- and 3,000-L bioreactors, leading to the development of a process for granular kefir biomass production. The results validated the laboratory-scale experiments and the avoidance of centrifugal separators due to granular biomass formation. Pilot-plant operations showed kefir to be highly resistant to contamination under actual industrial conditions and no serious problems in handling of raw materials and equipment were observed. Economic analysis showed a 20% higher cost of the market price of products, with added value of up to 15.9 x 10(9) within the European Union.

Aerobiosis↗

PubMed2002

Low-temperature brewing using yeast immobilized on dried figs.

Dried figs, following exhaustive extraction of their residual sugars with water, were used for immobilization of Saccharomyces cerevisiae AXAZ-1. The immobilized biocatalyst was used in repeated batch fermentations of glucose at 30 degrees C, where significant reduction of the fermentation time was observed, falling from 65 h in the first batch to 7 h after the sixth batch. Repeated fermentations of wort at room and low temperatures resulted in fermentation times that fell from 26 to 20 h and from 27 to 24 days at 18 and 3 degrees C, respectively. Ethanol and beer productivities were high, showing suitability of the biocatalyst for low-temperature brewing. Diacetyl concentrations were low (0.3-0.5 mg/L), and polyphenols were lower than in commercial products and decreased as the fermentation temperature was decreased (126-50 mg/L). Ethyl acetate concentrations increased from 53 to 88 mg/L as the temperature was decreased, while the concentration of amyl alcohols at 3 degrees C (58 mg/L) was lower than half of that at 18 degrees C (125 mg/L). The beers produced at the end of the main fermentation had a fine clarity and a special fruity figlike aroma and taste, distinct from commercial products and more intense than beers produced by cells immobilized on other food-grade supports (gluten pellets or delignified cellulosic materials). GC-MS analysis did not show significant differences in the qualitative composition of the aroma compounds of the beers produced by immobilized and free cells.

1-Propanol↗

PubMed2001

Low-temperature brewing by freeze-dried immobilized cells on gluten pellets.

A biocatalyst, prepared by the immobilization of a cryotolerant strain of Saccharomyces cerevisiae on gluten pellets, was freeze-dried without any protecting medium and used for repeated batch fermentations of wort for each of the temperatures 15, 10, 5, and 0 degrees C. The fermentation time for freeze-dried immobilized cells was about 2-fold that of the corresponding time for wet immobilized cells on gluten pellets, and lower than the corresponding time for freeze-dried free cells, especially at 5 and 0 degrees C. Beers produced by freeze-dried immobilized cells contained alcohol levels in the range of 5.0-5.5% v/v, diacetyl concentrations lower than 0.5 mg/L, polyphenol concentrations lower than 145.5 mg/L, and free cell concentrations lower than 3 g/L. As a result, they had a very good clarity after the end of primary fermentation. The amounts of amyl alcohols were lower than 129.1 mg/L and reduced as the temperature was decreased. Ethyl acetate concentrations were found in the range of 22.1-29.2 mg/L, giving a very good aroma and taste in the produced beers.

Alcohols↗