The effects of fortification of yogurt with various functional flours on survival and growth of probiotic bacteria and sensory properties of the yogurt

Purpose The purpose of this study is to determine the viability of Lacticaseibacillus rhamnosus GR-1 (L. rhamnosus GR-1) in five yogurt samples with or without quinoa, chickpea, soybean and rice flour over various fermentation periods and refrigerated storage durations, with a focus on exploring the potential of functional foods, which provide health benefits beyond nutritional value. Additionally, the study aimed to evaluate consumer acceptance of yogurt fortified with functional flour. Using a nine-point hedonic scale, from 1 (dislike extremely) to 9 (like extremely), participants rated appearance, flavour, texture and overall acceptability. Design/methodology/approach The samples were inoculated with the probiotic strain L. rhamnosus GR-1 and fermented for 0, 2, 4 and 6 h at 38°C, followed by refrigerated storage at 4°C for 1, 15 and 30 days, respectively. Microbial enumeration was performed throughout fermentation and storage to assess the viability of L. rhamnosus GR-1. A sensory evaluation involving 86 participants was conducted to assess the consumer acceptability of the yogurt samples. Findings Notably, L. rhamnosus GR-1 achieved viable counts of 108 colony-forming units per mL in all treatments at all fermentation time points. Over the 30-day storage period, no statistically significant differences (p < 0.05) in average pH values were observed among the five treatments, and within each treatment, pH levels remained stable, with an overall mean of 4.2 ± 0.64. Treatment 4, which featured rice flour fortification, received higher hedonic scores from sensory panellists in terms of appearance, flavour, texture and overall acceptability. These findings indicate that incorporating functional flours in conjunction with cow’s milk effectively promotes and preserves the viability of L. rhamnosus GR-1 in yogurt. Originality/value Exploring the potential of probiotic yogurt enriched with diverse functional flours to enhance nutritional content and health benefits as well as attract new consumers, this study addressed a critical gap in understanding consumer perceptions and generated insights for creating innovative and health-promoting dairy products.