Abstract:

This research investigated unripe banana starch as a protectant for Lactobacillus plantarum during the freeze
drying process and its effect on acid and bile salt tolerance and storage stability of the lactic acid bacterium, as well as
their synergistic antioxidant effect aiming to provide an idea and theoretical foundation for deep processing, development
and probiotic bacterial protection of banana. Unripe banana starch from low maturity banana contained higher level of
type 2 resistant starch. The experimental results indicated that unripe banana starch had synergistic antioxidant effect with
Lactobacillus plantarum in scavenging 63.62% of 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radicals, which was higher
than the sum of their individual effects. The lactic acid bacterium could attach to the surface of the starch granules to use
it slowly as a nutrient source. Meanwhile, unripe banana starch could significantly increase survival rate (up to 73.17%)
of Lactobacillus plantarum during freeze drying, and its protective effect was better than that of glycerol and mycose,
respectively. This study also suggests the potential of unripe banana starch to increase the tolerance of Lactobacillus
plantarum to acid and bile salt, and enhance of the stability of synbiotic products.

Key words: probiotic viability, unripe banana starch, lactic acid bacteria, freeze-drying, protective effect