Quality and biological properties of vinegar processed from non-valorized fruits in Southern Portugal

The processing of vinegar from non-valorized fruits and agricultural surpluses is an attractive strategy for biomass waste management. The present study aimed to characterize vinegar of fermented fruits, namely fresh fig, plum, dried fig, grape, raspberry, and apricot. Physicochemical and microbial quality, total phenolic content (TPC), total flavonoid content (TFC), total antioxidant capacity (TAC), mineral composition, and antimicrobial capacity against bacteria and yeasts were studied. Grape and apricot vinegar had the highest values of TAC (39.31±0.25, 34.10±1.44 DPPH µg Trolox/100 mL, respectively), while grape contained the highest TFC (35.73±3.86 mg catechin/100 mL) and raspberry and fresh fig, the highest TPC (55.40±1.1, 64.10±0.0 mg gallic acid/100 mL, respectively). Potassium, calcium and sodium were the most abundant minerals in the vinegars with dried fig standing out for its richness in potassium 1223.83±89.48 mg/L, calcium 17.70±1.31 mg/L, magnesium 2.39±0.24 mg/L, and zinc 4.33±0.17 mg/L. The enterobacteria Cronobacter sakazakii and Salmonella Typhimurium were the most tolerant (10.00±0.00-26.39±1.60 mm), while Pseudomonas aeruginosa was the most sensitive bacteria (26.36±3.61-40.17±2.72 mm) as well as Gram + (Staphylococcus aureus, Listeria innocua) (21,20±8,37-31.11±2.41 mm). The acetification processes resulted in vinegars with a good hygienic status, and levels of acetic acid (≥5%) complying with the legislation.