Determination of the change in some quality characteristics of fermented almond milk obtained by adding fruit juice in different ratios

In this study, the changes in some quality (pH, titration acidity), survival of Lactobacillus acidophilus amount, mold and yeast numbers, sensory evaluations, and rheological properties of fermented almond milk samples with and without added 100% fruit juice of two types (orange and pineapple juice) at 3 different ratios (10%, 20% and 30%) were investigated. The pH values of fermented almond milk samples with and without orange and pineapple juice in different ratios varied between 3.97-4.40 and 3.99-4.28 at the end of fermentation stage, 4.33-4.77 and 4.48-4.95 on the 7th day, 4.35-4.87 and 4.54-4.93 on day 14th day, respectively. Titratable acidity values of fermented almond milk samples with and without added orange juice or pineapple juice changed between 0.178%–0.478% and 0.186%–0.360% at the end of fermentation, respectively. The values increased during storage regardless of fruit juice type. The lowest pH and highest titratable acidity values were obtained in the samples with 30% fruit juice added. It was determined that the L. acidophilus content of fermented almond milk samples with added orange juice varied between 7.58-7.95 log cfu/ml at the end of fermentation stage. It was determined that there was a slight decreasing trend during the storage periods. Fermented almond milk samples with added pineapple juice, it was determined that the amount of L. acidophilus content at the end of fermentation periods varied between 7.28-7.74 and showed a slight tendency to decreased during storage periods. Mold and yeast were not detected in any of the fermented almond milk samples. It was determined that fermented almond milk samples showed non-Newtonian pseudoplastic flow behavior. In addition, the most suitable rheological model for the flow behavior of fermented almond milk samples with added orange and pineapple juice was the Power-Law and Herschel-Bulkley model, respectively. As a result of the sensory evaluation, it was determined that the general acceptability of fermented almond milk samples with and without added orange and pineapple juice at different rates was found in the samples with 30% fruit juice. It is thought that the results of this study can provide valuable information for equipment and pumping systems that can be installed on an industrial scale.