Dynamics of Bioactive Compounds and Their Relationship with Antioxidant and Antimicrobial Activity in the Pulp, Peel, and Seeds of ‘Salak’ During Ripening

Fruit is an important source of bioactive compounds, and making full use of them can contribute to the development of natural alternatives to microbial resistance. This study aimed to evaluate the dynamics of bioactive compounds and their relationship with antioxidant and antimicrobial activity in the pulp, peel, and seeds of Salacca zalacca at three stages of ripeness (M1, 30 days after flowering; M2, 90 days after flowering; and M3, 120 days after flowering). The physicochemical characteristics (weight, size, pH, soluble solids, titratable acidity, moisture, ash, and minerals) and the bioactive compounds (vitamin C, organic acids, carotenoids, chlorophylls, and phenolic compounds) were determined using liquid chromatography. Antioxidant activity was determined using the ABTS and DPPH methods, and antimicrobial activity was assessed against Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Streptococcus mutans, Candida albicans and Candida tropicalis. The results showed that the pulp had the highest concentrations of malic acid (8018.6 mg/100 g DW in M1); the peel in M1 had the highest concentrations of chlorogenic (705.0 mg/100 g DW), caffeic (321.0 mg/100 g DW) and ferulic acids (173.5 mg/100 g DW); and the seeds had the highest levels of vitamin C (16.81 mg/100 g DW in M2). The pulp in M2 and M3 and the peel in M2 exhibited the highest antioxidant capacity (5.5 mmol ET/100 g DW by DPPH), as well as the most potent antimicrobial activity against S. aureus and E. coli. In conclusion, the peel, in addition to the edible pulp, represents a relevant source of bioactive compounds with potential applications in functional foods and natural products.