Regulation of acetic acid production by homo- and heterofermentative lactobacilli in whole-wheat sour-doughs.
The efficiency of sour-dough as a possible preservative agent of microbial spoilage of bread depends on its acetic acid content. As a secondary metabolite of sugar fermentation by lactic acid bacteria, acetic acid may be promoted in the presence of O2 or H+ acceptors. This paper studies the influence of O2 and high fructose content products (pure sugar, invert sugar, fructose syrup) addition on acetic acid production by hetero- (Lactobacillus brevis 25a, B-21, L-62; L. sanfrancisco L-99) and homofermentative (L. plantarum B-39) lactobacilli in whole-wheat sour-doughs [280 and 250 dough yield (DY)]. The pH and total titratable acidity (TTA) of sour-doughs after 44 h fermentation varied with DY and strain. As expected, the addition of O2 promoted greater increases in TTA with heterofermentative lactobacilli (15-42%) than with L. plantarum (15%). Fructose addition was only effective for heterofermentative strains, but the overall effects were smaller than those observed for oxygenation. The ability of lactobacilli to produce acetic acid in sour-doughs without treatment varied from 0.16 g/100 g flour at 44 h (B-39, 280, 350 DY) to 0.47-0.65% (L-62, 280, 350 DY). The production of acetic acid was positively promoted by all treatments. Oxygenation was again the most effective way of inducing acetic acid production; increases ranged from 54% (B-21) to 269% (L-99, 350 DY). The addition of H+ acceptors had variable effects.(ABSTRACT TRUNCATED AT 250 WORDS)
Laboratorio de Cereales, Instituto de Agroquímica y Tecnología de Alimentos (CSIC), Valencia, Spain.
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Martínez-Anaya
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Llin
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Pilar Macías
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D000085:Acetates / Q000032:analysis / Q000378:metabolism*; D019342:Acetic Acid; D001939:Bread; D003470:Culture Media; D005285:Fermentation / Q000187:drug effects; D005632:Fructose / Q000494:pharmacology; D007778:Lactobacillus / Q000378:metabolism*; D010100:Oxygen / Q000494:pharmacology; D013045:Species Specificity
D000085:Acetates; D003470:Culture Media; D005632:Fructose; D019342:Acetic Acid; D010100:Oxygen