Organic acids profiles in lactose-hydrolyzed yogurt with different matrix composition

CLAUDIA INÉS VÉNICA; MARÍA CRISTINA PEROTTI; CARINA VIVIANA BERGAMINI

DAIRY SCIENCE & TECHNOLOGY

Springer

Año: 2014 vol. 94 p. 561 - 580

1958-5586

The composition of the dairy matrix used in yogurt manufacture couldinfluence the metabolic activity of yogurt starter and the compounds producedduring fermentation. In this way, the lactose hydrolysis with a β-galactosidaseenzyme and the supplementation with dairy powders to obtain different types ofdelactosed yogurts for lactose-intolerant people modifies the milk base composition.In this work, we studied the influence of the addition of different dosesof β-galactosidase and levels of dairy powders on organic acids profile duringthe manufacture and storage of two varieties of yogurt (natural and sweetened).Lactose, glucose, galactose, titratable acidity, fermentation time, and microbiologicalcounts were also evaluated. The mean proportions of lactose/glucose/galactose in relation to the total sugars were 18:36:46 in hydrolyzed yogurts,while they were 81:4:15 in unhydrolyzed ones. In supplemented yogurts, thecontent of lactose, citric, orotic, and hippuric acids were significantly increased.The starter population was similar in all yogurts, but some changes in theiractivity were evidenced due to both factors studied. The fermentation time wasslightly increased, and the lactic acid content and the titratable acidity weresignificantly increased due to fortification while they were decreased by enzymeaddition. These results are probably due to the increase in the buffer propertiesof the milk base by the dairy powder addition and due to an inhibition of thestarter activity caused by changes in the carbohydrate profile. The resultsdemonstrated that the changes in the matrix composition of the yogurt affectedthe organic acids profile, above all the lactic acid content.