Effects of Lacticaseibacillus casei Zhang addition on physicochemical properties and metabolomics of fermented camel milk during storage

<i>Lacticaseibacillus casei</i> Zhang (<i>L. casei</i> Zhang) was used as an auxiliary starter culture to explore its application in camel milk fermentation. This study evaluated the effects of <i>L</i>. <i>casei</i> Zhang supplementation on viable cell count, acidity, texture, insulin-like growth factor 1 (IGF-1) retention, and metabolite profiles over a 21-day storage period. <i>L. casei</i> Zhang enhanced the retention rate of active IGF-1 from 52.95% to 59.13% and mitigated the progression of acidity (from 125 °T to 97.5 °T) compared with the control group. Additionally, <i>L. casei</i> Zhang significantly improved viscosity and promoted the formation of gel structures. Furthermore, its addition significantly influenced the production of key metabolites, including adenosine diphosphate, oleuropein, and threonine-tryptophan (<i>P</i> < 0.05). These findings highlight the potential of <i>L</i>. <i>casei</i> Zhang as an effective auxiliary starter culture for camel milk fermentation, enhancing its physicochemical properties and modulating its metabolomic profile.