Effects of mung bean starch/guar gum-based edible emulsion coatings on the staling and safety of rice cakes

Antimicrobial starch/gum-based edible emulsion coatings were developed to improve the storage stability of rice cakes by retarding starch retrogradation and inhibiting microbial growth. Rice cakes were coated with mung bean starch (MBS) and guar gum (GG) containing various concentrations of sunflower seed oil (SO). Among these, the (2 g MBS +0.75 g GG +1.5 g SO) / 100 g (optimum) decreased the hardness of rice cakes by 29 % and the crystallization rate (k) by 24 % compared with those of uncoated samples. The moisture loss in uncoated samples was markedly higher than that in the optimum blend-coated samples. Crystallinity analysis revealed the retarding effect of the developed coatings in starch retrogradation. Furthermore, adding 0.8 % (w/w) grapefruit seed extract to the optimum blend led to a distinct antimicrobial activity. Therefore, the newly developed edible coating was effective in maintaining the quality and safety of rice cakes.