Development, optimization and integrated characterization of rice-based yogurt alternatives enriched with roasted and non-roasted sprouted barley flour.

Abstract

Plant-based yogurt substitutes ("gurts"), whose market growth is steadily increasing, have emerged as a promising option to promote more sustainable diets and food systems, especially when produced with locally sourced or low-input crops like barley. In this study, a novel gurt made with rice (10 %) and sprouted barley (5 %), was designed. Four lactic acid bacteria strains, Levilactobacillus brevis AM7, Leuconostoc pseudomesenteroides DSM20193, Lactiplantibacillus plantarum 18S9 and H64, were used as starters for making prototypes. Although with some differences in their acidification kinetics and proteolysis, all the strains adapted to the matrix. Then the formulation and production process were optimized. The use of sprouted barley, compared to raw flours, provided a content of amino acids 9-fold higher, further increased (up to 35 %) by the fermentation, and a more complex aroma profile characterized by the presence of furans and aldehydes. However, the high amylolytic activity in sprouted barley interfered with starch gelatinization decreasing the viscosity of the products from 3.3 to 0.08 Pa∗s. To overcome this challenge and obtain a creamy and spoonable product, sprouted barley flour was roasted, deactivating the enzymes and conferring a nutty and toasted flavor to the gurts due to the presence of pyrazines. The stability of the key biochemical and microbiological parameters during refrigerated storage was also assessed. Hence, plant-based gurts made with sprouted barley, emerge as a sustainable and health-promoting substitute to traditional dairy yogurts.