Changes of low-abundance peptides in frozen orange juice before and after frozen storage and pasteurization processing, and their contribution to ACE inhibition activity.

The direct-to-business product is the core sector for the sustainable production of all kinds of direct-to-consumer fruit and vegetable products. Additionally, it's also an effective way to reduce fruit and postharvest loss. However, unlike other agri-foods, few studies focus on the quality of frozen fruit juice. Fruit juice freezing is a vital practice to ensure sustainable supply chain in food and beverage industry. Our research centered on a six-year monitoring analysis of unpasteurized and pasteurized frozen orange juice. We examined the metabolite and peptide profiles using metabolomics and peptidomics approaches, as well as assessing angiotensin-converting enzyme (ACE) inhibition activity through a rapid ACE assay. Based on metabolomics and peptidomics analysis of orange juice, low-abundance peptides in orange juice have demonstrated a heightened sensitivity to frozen storage and pasteurization processing, outperforming overall metabolites. Frozen storage and pasteurization processing affect the level of predicted bioactive peptides as well as ACE inhibition activity in orange juice, and the peptide-rich fraction contributes to the ACE inhibition activity of orange juice. We synthesized 14 peptides and measured their ACE inhibition activity. Five strong ACE inhibitory peptides with IC50 values ranging from 0.31 to 1.93 mg/mL were identified, and their concentrations were found to decrease after frozen storage and pasteurization. As far as we know, this study is the first to focus on low-abundance peptides in industrial samples of orange juice, providing data on their alterations during a six-year monitoring analysis of frozen storage and before and after pasteurization.