Incorporation of ultrasound-assisted treatment in cheese to accelerate ripening of Kaşar cheese: Changes in cheese microbiota, proteolysis, enzyme activities and volatile profiles

Abstract

This study aimed to assess the impact of using LAB strains (Lactobacillus helveticus DPC 4571 and Lactobacillus casei ATCC 334) directly or after sonication on the quality and ripening of Kaşar cheese. Experimental cheeses were produced with a combination of cheese starters (Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus), adjuncts and sonicated cultures. The cheeses showed remarkable variations in titratable acidity and pH. The bacterial counts showed that sonication was effective on adjunct cultures, causing faster and stronger autolysis of L. helveticus DPC 4571 and an increase in L. casei ATCC 334 during ripening. Cheeses containing adjunct cultures exhibited higher proteolysis, with increased hydrolysis of αs₁- and β-caseins. Aminopeptidases activities increased during ripening by adjuncts and sonicated-adjunct cultures. The use of adjunct culture resulted in a greater increase in the free amino acid content. Adjuncts and sonicated-adjunct cultures increased both the quantity and diversity of some volatiles. In conclusion, the inclusion of sonicated culture in the starter system offered a potential approach to accelerate cheese ripening and improve cheese quality.