Authors
Stefanija Steinweg, Jelena Zagorska, Kristine Majore, Vitalijs Komasilovs, Vitalijs Radenkovs, Inga Ciprovica
Published in
Food science & nutrition. Volume 14. Issue 8. Pages e72199. Epub Aug 02, 2026.
Abstract
Starter culture (SC) composition and milk matrix characteristics shape fermentation and proteolysis-related changes in fermented milk (FM). This study evaluated the effects of milk origin (organic (ORG) and conventional (CNV)), commercial thermophilic SCs composition, and 7-day refrigerated storage on bacterial viability, proteolytic activity, protein fraction (PF) hydrolysis, and free amino acid (FAA) accumulation. ORG and CNV pasteurized milk collected over 1 year (twice outdoor and indoor period) was fermented with commercial starters containing Lactobacillus delbrueckii subsp. bulgaricus, Lactobacillus helveticus, and Streptococcus thermophilus. Fermentation reduced pH to 4.60-4.63 and increased proteolytic activity from 68.50-72.00 AU in pasteurized milk to 140.83-169.67 AU in FM. After storage, proteolytic activity further increased to 187.33-234.00 AU, with the highest value in CNV/TCC-20. Nonprotein nitrogen compounds increased from 0.29 g 100 g-1 to 0.33-0.42 g 100 g-1 after storage. Total identified PFs content decreased by 8.0%-24.2% after fermentation, with the greatest reduction in CNV/YFL902, and TCC-20 samples showed further decreases of approximately 22%-24% during storage. Total FAAs content increased by 6.7%-30.4% after fermentation, but after storage in all samples, except YFL902, decreased by 18.1%-46.8%. Overall, SC composition and storage time dominated proteolysis-related changes, while milk origin mainly modulated selected storage responses.
PMID:
42548958
Bibliographic data and abstract were imported from PubMed on 04 Aug 2026.
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