Microbial quality and sensory evaluation of probiotic yogurt fortified with functional seeds

Aim: This study aimed to assess the viability of Lacticaseibacillus rhamnosus GR-1 in four yogurt formulations with or without flax, chia, and hemp seeds during multiple time points across fermentation and cold storage. Additionally, the study evaluated consumer acceptance of the seed-fortified yogurts based on ratings of appearance, flavour, texture, and overall acceptability. Methods: Four yogurt samples were inoculated with the probiotic strain L. rhamnosus GR-1 and fermented for up to 6 h at 38°C, followed by refrigerated storage at 4°C for up to 30 days, respectively. Microbial enumeration was performed throughout fermentation and storage to assess the viability of L. rhamnosus GR-1. 84 participants engaged in a sensory evaluation where the consumer acceptability of the yogurt samples was evaluated. Results: Microbial analysis showed consistent viable counts of L. rhamnosus GR-1 across all fermentation and storage time points, where the sample containing chia seeds maintained the highest levels of probiotic viability. pH significantly decreased (p < 0.05) during fermentation in all treatments, with further reductions during storage only in the flax, hemp, and chia samples. Sensory evaluation revealed that the control scored highest in appearance, flavour, texture, and overall acceptability (p < 0.001). While participants showed the highest preference for the control sample, 77% indicated they would consider purchasing probiotic yogurt. Conclusions: Overall, adding flax, hemp, and chia seeds supports the viability of L. rhamnosus GR-1 in probiotic yogurt. Seed mucilage may play a vital role in the growth and viability of probiotics in yogurt products. The findings from this research provide a valuable foundation for the development of more nutrient-dense and consumer-friendly probiotic yogurt products.