- Effect of Preservatives on the Quality of Soymilk produced

Abstract

the study was conducted in order to identify or evaluate the effect of preservatives on soymilk. This evaluation was done through laboratory tests and sensory evaluation with 10 semi trend panelists. 5 samples were taken for the laboratory tests to evaluate the physical properties (pH, titrable acidity and TSS) of the soymilk and microbial enumeration to determine the shelf life of the soymilk. The sample were taken by adding two preservatives in different concentration. The preservatives used were benzoic acid and citric acid. The samples were A1(citric acid with a concentration of 0.3ml/L), A2(citric acid with a concentration of 0.6ml/L), B1(benzoic acid with a concentration of 0.02g/100ml), B2(benzoic acid with a concentration of 0.05g/100ml) and C (control or sample without preservative). The experimental design used for this study was 2x2 factorial. In the experiment, the sample with a maximum pH value was sample C (5.24 ± 0.09) and the sample with a minimum pH value was sample B2(4.40 ± 0.02). according to the result sample B2 is the most acidic from the five samples and sample C is the least acidic from the five samples. The sample with a maximum titrable acidity was sample C (0.55% ± 0.03) from the five samples and the minimum was sample B2(0.36% ± 0.04). according to this result less percent of lactic acid was present in sample C and more percent of lactic acid was present in sample B2. The maximum value of TSS observed from the five sample was sample C (6.63 ± 0.21) and the minimum value was sample B2(6.58 ± 0.23). according to this, there is no significant difference between the five samples. In the sensory evaluation, sample A1 has the highest overall acceptability (6.80 ± 0.63) from the five samples. In the microbial enumeration, sample B2 has the least CFU/g (0.9*103 in 10-2 dilution, 1.3*105 in 10-4 dilution and 1.7*107 in 10-6 dilution) from the five sample on day seven. According to this result sample B2 has the minimum of LAB count and it is preferable because, it is not favorable for the growth of microorganisms. So benzoic acid with the concentration of 0.05g/100ml was the best preservative to increase the shelf life of soymilk when compared with citric acid