Investigation of some physicochemical and survival of probiotic bacteria properties of industrial synbiotic juices by Response Surface and D-Optimal design with incomplete factorial

In recent years, consumers, in addition to considering the nutritional characteristics that are normally a desired food, also pay special attention to the health characteristics of the product. Today, probiotic juices have not received much attention in the industry and have little research history. Therefore, choosing apple and cherry juices as a high pH range can be a model for other juices.

In this study, the effect of 5 variables including fruit type (apple, cherry), inulin, type of probiotic microorganisms (Lactobacillus acidophilus and Lactobacillus casei) and probiotic addition method (encapsulated and free) and storage time (1, 7, 14 and 21 days) were investigated). Some physicochemical properties of juices (turbidity, viscosity, total sugar and vitamin C) were studied. The D-Optimal response surface methodology with incomplete factorial was used to design the experiment and its analysis was performed with SAS 4.5 software.

Analysis of variance at 5% level of significance showed that except for turbidity, other independent variables had significant effects (p < 0.05) on dependent variables in this study. In the microorganisms of cherry encapsulation, the amount of turbidity is constant (approximately 4) and in free cells this amount is reduced (1.5). In apple fruit, the amount of turbidity is constant in encapsulated and free (2.8). The viscosity results showed that apple juice has a minimum viscosity (1.25) and cherry juice has a high viscosity (1.32), which depends on the type of fruit composition and its formulation. Also, the results of total sugar showed that apples have the highest percentage of sugar (10.2) and cherries have the lowest percentage of sugar (4.1). Within a month, these values were higher in the encapsulation than in the free, which was due to less fermentation by microbes. The vitamin C chart shows that apples had the lowest amount (4%) and cherries had the highest amount (18%). Encapsulated and free microbes had little effect on vitamin C.

The results of this study showed that synbiotic juice can be introduced to the market as a profitable new product with a maximum expiration time of one month according to physicochemical analysis. In addition, samples containing encapsulated microorganisms have better storage time and organoleptic properties than others. Also, in acidic fruits, this shelf life is reduced, which from the twenty-first day onwards, the physicochemical analysis of the juice changes significantly and becomes unusable.