Analyzing Organic Acids in Fruit-Based Kombucha Analogues Using HPLC

Kombucha is a slightly sweet and acidic drink generally produced through fermenting black or green tea (Camellia sinensis) using sugar and a cellulose biofilm containing a symbiotic culture of bacteria and yeasts (SCOBY) (1). A recent study published in Food Technology and Biotechnology (2), set out to develop kombucha analogues using the agro-industrial by-products of fruit pulp processing. In addition to offering a new product to the marketplace consumers, the beverage preparation is associated with the use of fruit by-products and the reduction of their environmental impact, thereby minimizing their improper disposal.

Formulations were made using by-products that were preselected based on antioxidant activity. The scientists investigated fermentation kinetics, physicochemical and sensory properties, and organic acid profile were investigated. High-performance liquid chromatography (HPLC) was used to determine the organic acid content of six tropical fruits:acerola (Malpighia emarginata), guava (Psidium guajava), tamarind (Tamarindus indica), passion fruit (Passiflora edulis), mombin (Spondias mombin) and pineapple (Ananas comosus).

Fruit by-products carry high nutritional content, frequently higher than that of their edible parts. These by-products may also contain bioactive compounds with a higher antioxidant capacity than the pulp as well (3). Also, agro-industrial by-products contain many fermentable sugars and nutrients from which microorganisms can produce various substances of industrial importance that can be used for the development of various products, including kombucha (4).

Previous literature has outlined the use of other products as alternatives to tea to produce kombucha, including herbal infusions, wax mallow flowers, coffee, oak leaves, eucalyptus, bay leaves, fruit juices, milk and soya products (5,6). Depending on the raw material used to produce kombucha, the final product may have improved chemical composition, sensory and biological properties, which can result in new possibilities for beverage production, potentially offering products with additional health benefits for the consumers (6).

The research revealed that the fermented acerola, guava, and tamarind beverages have achieved satisfactory results regarding chemical and physical parameters and are considered safe for human consumption from a microbiological point of view. During the evaluation of fermentation kinetics, it was observed that the pH and soluble solid content decreased as the acidity increased. Among all beverages analyzed, those obtained using acerola by-product had the highest antioxidant potential. A more than ample number of organic acids was found in all formulations, with the beverage produced from acerola by-product yielding the highest concentrations of glucuronic, ascorbic, lactic, and acetic acids. The only formulation in which citric acid was quantified was guava by-product, which was the formulation receiving the highest acceptance score among the panel of tasters participating in the study, followed by the formulation with the tamarind by-product and the one with the acerola by-product. All samples were considered acceptable by the panelists. The importance of this work extends to the associated benefits, as it offers new food alternatives with high nutritional content and fully utilizes fruit by-products (2).

Homemade raw kombucha tea with pineapple. © cd - stock.adobe.com

References

1. Coelho, R.; Almeida, A.; Amaral, R.; Mota, R.; Sousa, P. Kombucha. Int. J. Gastron. Food Sci. 2020, 22. DOI: 10.1016/j.ijgfs.2020.100272
2. Câmara, G. B.; do Prado, G. M.; de Sousa, P. H. M.; Viera, V. B.; de Araújo, H. W. C.; Lima, A. R. N.; Filho, A. A. L. A.; Vieira, Í. G. P.; Fernandes, V. B.; Oliveira, L. S.; Ribeiro da Silva, L. M. Biotransformation of Tropical Fruit By-Products for the Development of Kombucha Analogues with Antioxidant Potential. Food Technol. Biotechnol. 2024, 62 (3), 361–372. DOI: 10.17113/ftb.62.03.24.8350
3. Ribeiro da Silva, L.; Figueiredo, E.; Ricardo, N.; Vieira, I.; Figueiredo, R.; Brasil, I. Quantification of Bioactive Compounds in Pulps and By-Products of Tropical Fruits from Brazil. Food Chem. 2014, 143, 398–404. DOI: 10.1016/j.foodchem.2013.08.001
4. Kapp. J.; Sumner, W. Kombucha: A Systematic Review of Empirical Evidence of Benefit to Human Health. Ann. Epidemiol. 2019, 30, 66–70. DOI: 10.1016/j.annepidem.2018.11.001.
5. Emiljanowicz, K.;Malinowska-Pańczyk, E. Kombucha Alternative Raw Materials - The Review. Crit. Rev. Food Sci. Nutr. 2020, 60 (19), 3185–3194. DOI: 10.1080/10408398.2019.1679714, PubMed: https://www.ncbi.nlm.nih.gov/pubmed/24377856/31657623
6. Silva, K.; Uekane, T.; de Miranda, J.; Ruiz, L.; da Motta, J.; Silva, C. Kombucha Beverage from Infusion of Unconventional Edible Plants and Green Tea: Characterization, Toxicity, Antioxidant Activities and Antimicrobial Properties. Biocatal. Agric. Biotechnol. 2021, 34. DOI: 10.1016/j.bcab.2021.102032