Biotransformation of Tropical Fruit By-Products for the Development of Kombucha Analogues with Antioxidant Potential.

Research background: In a country where millions of people have nutritional needs, innovative ways of producing food from commonly wasted agro-industrial by-products, can be an important alternative for the production of fermented beverages. In light of this, the aim of this study is to evaluate the potential of fruit by-products from acerola, guava and tamarind for the production of fermented beverages.

Experimental approach: Physicochemical and microbiological parameters, total antioxidant capacity and fermentation kinetics were investigated during the first (at 0, 48, 72, 96 and 168 h) and second fermentation (at 0 and 24 h). The acid profile of fermented beverages was determined by chromatography, and the sensory profile was determined by consumer acceptance test.

Results and conclusions: Physicochemical parameters of all formulations complied with current legislation and were of satisfactory microbiological quality. The reslts of fermentation kinetics showed that both pH and soluble solids content decreased - with an average final pH of 3.12, 2.85 and 2.78 for the acerola, guava and tamarind formulations, respectively - while acidity increased with final values of 0.94, 0.75 and 1 % for the same formulations. Of all formulations, tamarind had the highest total soluble solids content (8.17 g/100 g), and acerola had the highest antioxidant potential determined as Trolox equivalents ((20.0±0.8) μM/g). Organic acids were found in all samples, with mainly glucuronic acid detected in the kombucha beverages. All formulations showed satisfactory sensory acceptability, although the results were better for guava. The fruit by-products can be used as raw materials for the development of alternative kombucha beverages.

Novelty and scientific contribution: As consumers are increasingly selective in their food choices, the development of food products with high nutritional value has increased significantly in recent years. New types of fermentable beverages such as kombucha - using tropical fruit by-products to enhance their chemical composition, sensory properties and nutritional value - have created new opportunities for beverage consumption and offer greater health benefits than the traditional version, where only Camellia sinensis is used. The promotion of these co-products and their respective beverages is an excellent opportunity for sustainability and their commercialisation.