Enhancement of Bioactive Compounds in Tomato Paste via Lactic Acid Bacteria Fermentation and Its Potential Application in Olive Oil Fortification

The aim of this study was to evaluate the effect of fermentation in mono- and co-culture using lactic acid bacteria (LAB) on bioactive compounds and antioxidant capacity of tomato paste; subsequently, tomato paste was applied to extra virgin olive oil to improve its antioxidant properties and sensory acceptance. The fermentation process of tomato paste increased the LAB by more than 5 log10 (CFU/g), enhancing the total phenolic compounds, total carotenoids, total lycopene, and antioxidant capacity in the ranges of 47.88–108.33, 113.11–148.53, 19.46–45.94, and 23.31–60.11%, respectively, with L. casei showing the highest levels of both total phenolic compounds and total lycopene, while the consortium showed the highest antioxidant capacity. After 28 days of storage, olive oil added with LAB-fermented tomato paste by L. casei showed the highest antioxidant capacity (5.65 to 12.99%, p < 0.05) and the lowest acidity index (19.38–57.14%, p < 0.05). All olive oils with tomato paste showed values between “I like it” and “neither like nor dislike it”. The results indicate that fermentation boosts the production of interesting metabolites from tomatoes, improving the value of food products.