Microbiological properties, biogenic amines, total phenolic contents and antioxidant activities of goat kefir fortified with locust bean gum.

Kefir from goat milk is a functional fermented dairy product with probiotics, enhanced digestibility and a distinct nutritional profile. This study aimed to investigate the effects of the addition of different concentrations (0.05%, 0.1% and 0.2%) of locust bean gum (LBG) on some biofunctional and microbiological properties of goat milk kefir during 28 days of storage. Storage time was the predominant factor affecting microbial viability. Lactobacilli, lactococci, total mesophilic aerobic bacteria (TMAB), acetic acid bacteria (AAB) and Leuconostoc spp. decreased mainly during the first 14 days of storage, whereas yeast counts increased throughout storage. LBG supplementation significantly affected lactococci, AAB, yeast populations and tyrosine content, whereas no significant effects were observed for lactobacilli, TMAB and Leuconostoc spp. Tyrosine content ranged from 0.082 to 0.121 mg/g and increased significantly during storage. Kefir samples exhibited antibacterial activity against Listeria monocytogenes, Bacillus cereus and Salmonella Typhimurium. Individual biogenic amine concentrations in kefir samples ranged between 9.72 and 50.08 mg/kg. Although histamine was significantly affected by treatment, the effect was not consistent across LBG inclusion levels. Total phenolic content ranged from 6.39 to 8.74 mg gallic acid equivalents/100 g and increased significantly during storage, whereas antioxidant activity averaged 0.87 ± 0.25 µM Trolox/100 g and was not significantly affected by either LBG supplementation or storage time. Overall, storage time was the primary factor governing changes in goat milk kefir during refrigerated storage, whereas LBG supplementation exerted limited but selective effects depending on the quality parameter evaluated.