Food fermentations: microorganisms with technological beneficial use.

Microbial food cultures have directly or indirectly come under various regulatory frameworks in the course of the last decades. Several of those regulatory frameworks put emphasis on "the history of use", "traditional food", or "general recognition of safety". Authoritative lists of microorganisms with a documented use in food have therefore come into high demand.

Concomitant extracellular accumulation of alpha-keto acids and higher alcohols by Zygosaccharomyces rouxii.

Alpha-keto acids are key intermediates in the formation of higher alcohols, important flavor components in soy sauce, and produced by the salt-tolerant yeast Zygosaccharomyces rouxii. Unlike most of the higher alcohols, the alpha-keto acids are usually not extracellularly accumulated by Z. rouxii when it is cultivated with ammonium as the sole nitrogen source.

Bat2p is essential in Saccharomyces cerevisiae for fusel alcohol production on the non-fermentable carbon source ethanol.

Branched-chain amino acids (BCAAs) are key substrates in the formation of fusel alcohols, important flavour components in fermented foods. The first step in the catabolic BCAA degradation is a transaminase step, catalyzed by a branched-chain amino acid transaminase (BCAAT). Saccharomyces cerevisiae possesses a mitochondrial and a cytosolic BCAAT, Bat1p and Bat2p, respectively.

Identification of salt-induced genes of Zygosaccharomyces rouxii by using Saccharomyces cerevisiae GeneFilters.

Yeast GeneFilters containing all Saccharomyces cerevisiae open reading frame (ORF) sequences were used to elucidate gene activity in the osmotolerant yeast Zygosaccharomyces rouxii. Labelled cDNA derived from Z. rouxii was targeted to spotted S.

Immobilized salt-tolerant yeasts: application of a new polyethylene-oxide support in a continuous stirred-tank reactor for flavour production.

Immobilization of salt-tolerant yeasts considerably decreases the total time required for the flavour development in soy-sauce processes. For immobilization of cells, alginate gel is mostly used as support material. However, alginate is not very suitable for use in soy-sauce processes because alginate is sensitive to abrasion and chemically unstable towards the high salt content of the soy-sauce medium.