Potential of Cheese-Associated Lactic Acid Bacteria to Metabolize Citrate and Produce Organic Acids and Acetoin

Abstract

Lactic acid bacteria (LAB) are pivotal in shaping the technological, sensory, and safety aspects of dairy products. The evaluation of proteolytic activity, citrate utilization, milk pH reduction, and the production of organic compounds, acetoin, and diacetyl by cheese associated LAB strains was carried out, followed by Principal Component Analysis (PCA). Citrate utilization was observed in all <i>Leuconostoc</i> (<i>Le</i>.) <i>mesenteroides, Le. citreum, Lactococcus</i> (<i>Lc</i>.) <i>lactis, Lc. garvieae,</i> and <i>Limosilactobacillus</i> (<i>Lm</i>.) <i>fermentum</i> strains, and in some <i>Lacticaseibacillus</i> (<i>Lact</i>.) <i>casei</i> strains. Most strains exhibited proteolytic activity, reduced pH, and generated organic compounds. Multivariate PCA revealed <i>Le. mesenteroides</i> as a prolific producer of acetic, lactic, formic, and pyruvic acids and acetoin at 30 °C. <i>Enterococcus</i> sp. was distinguished from <i>Lact. casei</i> based on acetic, formic, and pyruvic acid production, while <i>Lact. casei</i> primarily produced lactic acid at 37 °C. At 42 °C, <i>Lactobacillus</i> (<i>L</i>.) <i>helveticus</i> and some <i>L. delbrueckii</i> subsp. <i>bulgaricus</i> strains excelled in acetoin production, whereas <i>L. delbrueckii</i> subsp. <i>bulgaricus</i> and <i>Streptococcus</i> (<i>S.</i>) <i>thermophilus</i> strains primarily produced lactic acid. <i>Lm. fermentum</i> stood out with its production of acetic, formic, and pyruvic acids. Overall, cheese-associated LAB strains exhibited diverse metabolic capabilities which contribute to desirable aroma, flavor, and safety of dairy products.