Interplay between kefir microbiota and berry by-products: evaluation of probiotic and prebiotic properties for functional food applications

Abstract

A functional food is defined as a food that contains biologically active components with proven health benefits, offering the potential to reduce the risk of specific chronic diseases or beneficially affect target functions beyond its basic nutritional functions. Currently, some food industries re-process their by-products and use them as functional food ingredients, making sustainable and stable economic growth. Industrial by-products generated in Jalisco, including berries, leads to losses of food products that can represent up to 40% of the processed volume. Further, berries generate high amounts of by-products during industry manufacturing. In this context, these berry by-products could be recovered and used successfully for different industry purposes, such as production of prebiotic ingredients. Prebiotics are substrates selectively utilized by probiotic microorganisms conferring a health benefit. The potential prebiotic food ingredients obtained from plants or food by-products need to be characterized to determine their properties and the mechanisms by which they exert health benefits, as well as how they impact the gut microbiota composition. Therefore, different commercial probiotics and microorganisms isolated from an artisanal milk kefir beverage were evaluate along with the fermentative capacity of ingredients from industrial berry by-products. Lactoccocus, Leuconostoc, Kluyveromyces and Lactobacillus species were isolated and identified through MALDI-TOF analysis. Overall, L. lactis BIOTEC007, K. lactis BIOTEC009, L. kefiri BIOTEC014 and L. pseudomesenteroides BIOTEC012 species demonstrated desirable probiotic-related properties such as auto aggregation, co-aggregation with pathogens, antimicrobial activity related to the production of organic acids and resistance to in vitro gastrointestinal digestion conditions. Regarding the berry by- products, bagasse of berries were obtained and characterized, showing antimicrobial activity, high content of bioactive compounds and a high content of fiber, proteins, and carbohydrates. Hence, when fermented by kefir isolated microorganisms such as L. lactis BIOTEC007, L. kefiri BIOTEC014 and L. rhamnosus GG, maximum growth absorbance values in blueberry and strawberry bagasse media were observed. Moreover, a substrate consumption assay showed a possible utilization of bagasse fibers and polyphenols. Finally, four synbiotic fermented beverages containing blueberry bagasse were formulated. The product fermented by L. lactis BIOTEC007 and L. rhamnosus GG were chosen as the best due to their physicochemical characteristics and sensorial attributes. The beverage also contained considerable levels of bioactive compounds including phenolic acids and anthocyanins. Finally, it was observed that this formulation with bagasse promoted the growth of microorganisms in the product and exerted in some way a protective effect, since they resisted the digestion stages in a better way than the isolates that were in a milk matrix with no bagasse as a control. These properties allow to confirm tha blueberry bagasse could be considered as a prospective prebiotic ingredient along with potential probiotic isolates in the formulation of functional fermented foods.