Produção e caracterização de iogurte produzidos com culturas láticas comerciais fermentadoras de lactose ou sacarose

Abstract

Among fermented milks, yogurt stands out given the growing demand from consumers for healthy foods. Therefore, the objective of this study is to produce yogurts using commercial lactic ferments that ferment lactose or sucrose and to characterize them regarding pH, acidity, and total lactic bacteria count using different culture media and carbohydrate supplements. To achieve this, the study will investigate the impact of using different lactic ferments (YOFLEX® MILD 1.0 and YOFLEX ACIDIFIX®), with lactose and sucrose as substrates, on the total lactic bacteria count in yogurt production, aiming to comply with current legislation. Emphasis will be placed on the role of Streptococcus thermophilus and Lactobacillus bulgaricus bacteria and the relationship between lactose and sucrose substrates in lactic bacteria counting, as well as the supplementation of these carbohydrates. Different lactic ferments, each with their specific characteristics, were employed to assess how they influence growth and lactic bacteria count. Additionally, M17 culture media from different brands, such as Biokar, Merck, and Oxoid, were used, highlighting the importance of selecting the appropriate culture medium for analytical purposes. The relationship between lactose and sucrose substrates in lactic bacteria counting was investigated, exploring how these sugars influence growth. This study emphasizes the importance of the proper choice of culture media and supplementation in the analysis of different lactic bacteria in produced yogurts, where M17 media from Biokar and Merck brands showed similar results, while M17 Oxoid, especially when supplemented with lactose, exhibited inconsistent results. Confirmation of the presence of lactic bacteria (S. thermophilus and L. bulgaricus) through microbiological techniques confirmed their identity. Regarding pH and acidity, there was a trend towards a reduction in pH over time, but acidity remained within regulatory limits.