Subprodutos de araticum, baru e pequi : caracterização química e física e fermentação por cepas probióticas

Abstract

Fruit by-products have gained attention due to their high nutritional value and the presence of bioactive compounds with beneficial health effects. These bioactive compounds can be metabolized by microorganisms, leading to the production of metabolites with positive physiological properties. So far, most studies evaluating chemical composition and fermentability of fruit by-products have been done with popular fruits, whereas little-known fruits, especially those from the Cerrado biome, are still poorly investigated. The aim of this study was to chemically and physically characterize araticum, baru and pequi by-products and to evaluate their fermentation by Lactobacillus acidophilus (La-5, LA3 and NCFM) and Bifidobacterium animalis subsp. lactis (Bb-12) probiotic strains. Araticum (bark and seeds), baru (mesocarp) and pequi (epicarp and external mesocarp) by-products were dried in an oven with forced air circulation (60-70 ° C) and characterized regarding their chemical composition, soluble and insoluble fibers and mineral amounts, water activity (Aw), color, total carotenoids (TC), total phenolic compounds (TPC) and in vitro antioxidant capacity. TPC accessibility was assessed by in vitro digestion during 6 h. Fermentation in vitro assay was carried out using modified MRS medium supplemented with fruit by-products and the following parameters were evaluated after incubation (48 h/37 °C): probiotic population, pH value; short chain fatty acid (SCFA - acetate, butyrate and propionate) and TPC contents and in vitro antioxidant capacity. Fruit by-products had low moisture amount (<10 g/100 g) and araticum by-product showed the highest levels of protein (9.66 g/100 g), lipids (9.51 g/100 g) and total dietary fiber (61.55 g/100 g). Insoluble fibers were prevailed in all by-products and pequi by-product had the highest amount of soluble fibers (14.62 g/100 g). The majority minerals were phosphorus, sulfur, potassium and calcium. Aw was the similar among byproducts and the chromatic characteristics (luminosity, a * and b *) were higher in baru byproduct. Pequi by-product showed the highest values of TPC (73.58 mg EAG/g), TC (3439.73 µg/100 g) and antioxidant capacity (ABTS = 1958.98 mM Trolox/g, DPPH = 1114.24 mM Trolox/g, FRAP = 3131.35 mM ferrous sulfate/g). In vitro accessibility of TPC ranged from 64.52 to 131.09% after in vitro digestion. Only Lactobacillus strains were able to ferment fruit by-products and the highest populations were obtained for NCFM (7.24 log CFU/mL) and La-5 (6.61 log CFU/mL) strains, both combined with araticum by-product, and for La-5 strain combined with pequi by-product (6.49 log CFU/mL). pH value reduced in the media fermented by Lactobacillus strains. SCFA were detected after fermentation and acetate showed the highest levels regardless the strain-by-product combination. However, the presence of fruit by-products had little impact on SCFA levels compared to the MRS with glucose. The greatest increase in TPC, DPPH and FRAP amounts (up to 71.9%, 53.3% and 208.8%, respectively) after fermentation was obtained for the media supplemented with baru by-product, compared to the non-fermented media; however these parameters reduced or slightly increased in media with pequi by-product. Cerrado fruits by-products showed high nutritional value and bioactive compounds, suggesting that they are new sources of antioxidants. Additionally, they supported the growth of Lactobacillus probiotic strains and were metabolized by these microorganisms. Araticum by-product and Lactobacillus association can result in innovative food with functional potential, besides contributing to reduce the environmental impact generated by the disposal of these residues.