Effect of pre- and post-fermentation grumixama addition on the viability, phenolic compounds, and antioxidant capacity of a munguba-based probiotic beverage

The plant-based beverage market has grown driven by dietary restrictions on animal milk, demanding innovations such as probiotic formulations rich in phenolics. However, the prevalence of conventional sources makes it essential to value neglected and underutilized species (NUS). Thus, the objective of this work was to develop a probiotic beverage from munguba seeds (Pachira aquatica) and evaluate the impact of grumixama (Eugenia brasiliensis) addition, pre- and post-fermentation, on cell viability, phenolic compounds and antioxidant capacity under refrigeration. Munguba fruits were collected at Quinta da Boa Vista (Rio de Janeiro) and grumixama was provided by the Integrated Center for Food and Nutrition, registered in SisGen under no. A18D314. To obtain the munguba plant extract, the samples were peeled, blanched, ground in water (1:4 w/v), filtered and pasteurized (62 °C/30 min). The probiotic beverages were formulated by inoculating the Nu-trish® ABT-5 starter culture (0.01% w/v; Lactobacillus acidophilus, Bifidobacterium sp. and Streptococcus thermophilus), evaluating the addition of 1% (w/v) freeze-dried grumixama after fermentation (FGA) and before the fermentation process (FGB). Fermentation was conducted at 41 °C until pH 4.5, followed by bottling and storage at 5 °C for 30 days, during which the viability of lactic acid bacteria (LAB), the concentration of total phenolic compounds (Folin–Ciocalteu) and antioxidant capacity (FRAP and TEAC) were determined. Data were evaluated by two-way ANOVA followed by Tukey's test (p < 0.05). Over 30 days under refrigeration, LAB counts decreased in both formulations. FGA ranged from 8.4±0.1 to 7.6±0.3 log CFU/mL, with no statistically significant variations, while FGB decreased from 7.8±0.1 to 6.8±0.8 log CFU/mL, showing a marked decline on day 21 (6.1±0.3 log CFU/mL). This suggests that the pre-fermentation addition of grumixama in FGB interfered with the growth and stability of lactic acid bacteria in the stationary phase. Post-fermentation addition (FGA) showed higher retention of total phenolic compounds and antioxidant capacity (FRAP and TEAC). Between days 0 and 14, a 50% reduction in antioxidant parameters was observed, suggesting an initial loss of stability possibly linked to oxidation and interactions between bioactive compounds and the beverage matrix. Although refrigeration slows chemical and biological reactions, it does not interrupt them. From day 14 onward, levels stabilized, with no significant differences relative to the analytical variability of the assay. Thus, this plant-based probiotic beverage shows promise for food applications, especially FGA, which maintained higher levels of LAB viability and phenolic compounds.

Acknowledgments

This study was financed by the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq; Processo: 404597/2023-8) and Fundação Carlos Chagas Filho de Amparo à Pesquisa do Estado do Rio de Janeiro (FAPERJ; E-26/210.827/2024). We also acknowledge the financial support from the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brasil (CAPES; Finance Code 001) and CNPq.