Evaluation of semi prepared probiotic dessert containing phycoerythrin and Lactobacillus plantarum for period of up to two months within the refrigerator

The isolation of functional bioactive compounds from microalgae as sustainable sources has emerged as a new area of focus in pharmacology and functional food research. The use of natural ingredients in food products has become very popular today, while desserts made with preservatives and artificial colors have been shown to significantly increase the risk of cancer. Therefore, this study aimed to extract phycoerythrin (PE) from the cyanobacterium Nostoc sp. and produce and evaluate a semi-prepared probiotic dessert containing Lactobacillus plantarum for 60 days. The stability of the PE was evaluated over 72 h at room temperature. Following this evaluation, dairy desserts containing nano-emulsion of PE and 1% L. plantarum were formulated under different treatments, C₀: no PE and L. plantarum, T₁: 0.5% PE; T₂: 1% PE; T₃: 1.5% PE; T₄: 2% PE. Then, different physicochemical composition, colorimetric properties, antimicrobial and antioxidant capabilities, and sensory evaluation were performed. Based on the results, protein content, moisture content, and texture stiffness showed that the addition of PE caused a significant increase by 1.59, 1.02, and 3.25 times in comparison to control, respectively. However, no significant effect on the fat and ash content of the samples was observed. The pH and acidity results also showed that the addition of PE increased and decreased in T₄ treatment by 1.02 and 0.87 times compared to the control on day 60, respectively (p < 0.05). Furthermore, the addition of PE caused a significant decrease in the brightness index (L*), which was 0.76 times in T₄ compared to the control sample. However, the yellowness and redness indexes had increased by 1.94 and 2.3 times, respectively. The total phenol content and antioxidant activity in T₄ treatment had also increased by 1.10 and 2.12 times compared to the control sample, respectively. The microbial analysis revealed no Escherichia coli growth in any of the treatments, and a 0.56 times decrease in the total count of mold and yeast in the T₄ treatment compared to the control sample. The survival of probiotic bacteria in T₄ treatment had increased by 1.08 times. The results of flavor and overall acceptability showed that the addition of PE caused a significant increase in the sensory evaluation, while odor and color had decreased. The results suggest that the prepared dairy dessert can serve as a beneficial probiotic product for a period of 60 days.