Fermentation of tomato juice by probiotic yeast.

Recent years have seen trends in the production of foods with recognised health benefits, including those containing probiotic microorganisms. Tomatoes are rich in bioactive compounds, including lycopene, vitamins C and A, potassium, saponins, and polyphenols, which possess antioxidant, anti-inflammatory, anti-carcinogenic, and cardioprotective properties. In the EU, the annual production of fresh tomatoes is approximately 16 million tonnes. Our study investigated the potential of fermenting tomato juice with the probiotic yeast Saccharomyces cerevisiae var. boulardii. We used tomato juice from "Tłocznia Szymanowice", Poland, as the raw material. Sugar, organic acid, and ethanol analyses were performed using HPLC. Polyphenols were determined using the Folin–Ciocalteu method. The Saccharomyces cerevisiae var. boulardii CNCM-I-745 culture was obtained from the commercial product Enterol 250 (Biocodex, France). The second dry wine strain—Saccharomyces bayanus BCS103 (Fermentis (Lesaffre), France)—was used to obtain reference results. Due to the low initial sugar content, we added 60 g/L of glucose as a fermentation substrate for the yeast. The fermentation process was carried out at 35°C for 7 days. The ethanol concentration of the tomato juices fermented with added glucose ranged from 28.87 to 31.23 g/L, depending on the strain. The polyphenol content in the fermented samples was close to the initial polyphenol content in the juices (24-26 mg GAE/100g). The fermented tomato juice retained much of its colour but lost its distinctive tomato taste and aroma, becoming dominated by a sour, yeasty, and alcoholic sensation. Although fruit and vegetable fermentation is a “newly” rediscovered trend, as is the appreciation of the role of probiotic foods, in the case of tomato juice, the unfavourable sensory changes in the final product, in our opinion, disqualify the potential market implementation of tomato juices fermented by S. boulardii.