Some quality characteristics and probiotic shelf life of yogurts (Lb. acidophilus) with spirulina

This study aims to determine the quality characteristics of the functional product obtained by enriching the yoghurt, an essential part of the human diet and frequently consumed daily, with Spirulina platensis, which stands out with its rich nutritional content and benefits for human health. For this purpose, 8 types of yoghurt, 4 classical and 4 probiotics, containing Spirulina platensis in 4 different ratios (0%, 0.3%, 0.6%, 0.9%) were produced. The probiotic shelf life and quality characteristics of the produced yoghurts were analyzed at 4 °C on the 1st, 7th, 14th, 21st and 28th days. The effect of Spirulina platensis powder in yogurt production on yogurt samples' physical and chemical properties was significant. In yoghurt samples, with increasing Spirulina platensis powder amount, dry matter, fat, protein, b*, and C* values increased, but L*, a* and H° values and viscosity decreased (p<0,01). The effect of Spirulina platensis powder used in yoghurt production on the textural properties of yoghurt samples was significant (p<0.01). The amount of Spirulina platensis powder in yoghurt samples and the hardness and internal stickiness values decreased. In addition, adding Spirulina platensis fell the elasticity value independent of the ratio in the classical group but did not create a significant difference in the probiotic group. Again, regardless of the ratio, it was determined that the addition of Spirulina platensis reduced the surface stickiness. During storage, the number of Lactobacillus acidophilus bacteria did not decrease below 106 log cfu/g in the probiotic yogurt samples. The viability rate of Lactobacillus acidophilus in probiotic yogurt samples was 100.12-101.70%. As a result of the sensory analysis, all of the yoghurt samples had scores between 4-5 out of 5 in terms of sensory evaluations (p>0.05). Considering all quality evaluations, a new enriched probiotic yoghurt with high nutritional value can be produced with Lactobacillus acidophilus and containing 0.6% Spirulina platensis (P0.6%). In addition, according to panellist evaluations, it was stated that the samples containing 0.9% Spirulina platensis could be developed as a product such as spicy yogurt sauce.