The influence of inulin on the survival of Lactobacillus casei in a synbiotic squash jam

Abstract

Inulin is a non-digestible linear polysaccharide. It cannot be digested in small intestine, but can be fermented in the colon by lactic acid bacteria and stimulates the growth of healthy bacteria. In this study, the effect of inulin addition on the survival of the probiotic strain Lactobacillus casei was assessed within the production of the symbiotic jam. Lactobacillus casei was inoculated to the produced squash jam in a density of 108 and 107CFU/ml. Then inulin was added at three different amounts (0.5, 1 and 1.5 percent). The jam inoculated with the probiotic strain and without inulin was considered as the control. Eight treatments and a control (totally 9 treatments) were analyzed in triplicate. The mean values were compared by Duncan's multiple range test at 95% confidence level. The samples were stored for four weeks at 4. Then pH, reducing sugar, acidity in terms of lactic acid, Brix and microbial counts were evaluated. The effect of the inulin percent, bacterial density and shelf life of the jam showed significant differences on microbial count (p>0.01). The effect of inulin percentages showed significant differences on the jam sugar (p>0.01). The sugar content of the synbiotic squash jam had a significant increase with the increase of inulin (p≥0.05). The highest amount of sugar belonged to the treatment T2N4 (150 g jam + 1.5 ×108CFU/ml Lactobacillus casei + 1.5% inulin) was (p>0.01). With the increase of inulin percentage and shelf life, the highest growth and survival of L. casei,equal to 8.968 Log CFU/ml, was observed in the treatment T1N3 (containing 150 g jam + 1.5 ×107CFU/ml Lactobacillus casei + 1% inulin) as the superior treatment. The results showed that both squash and inulin are suitable substrates for the growth of Lactobacillus casei.