The effect of different proportions of hydrocolloids and food emulsifiers on the physicochemical, textural and microbial properties of sponge cake during the storage period

In this research, three different types of hydrocolloids (chitosan ,tragacanth, hydroxy propyl methyl cellulose) 2 % on the basis of flour weight and three different kinds of emulsifiers (lecithin, glycerol mono stearate, propylene glycol) 1 % on the basis of flour weight, were added in different proportions to sponge cake's formulation  in order to assay quality indicators of cake. Bulk density, true density, aw (water activity), moisture, amylose content, texture analysis, microbial growth and colour (hue, chroma) were used as quality indices during cake's shelf life period (12 weeks). Colour, aw and firmness did not significantly affect by any of hydrocolloids and emulsifiers and they affected only by the storage time. HPMC and lecithin had the most effect on decreasing true density and bulk density respectively. Results indicated that chitosan was the most effective hydrocolloid for retention of moisture in cakes. The amylose content increased by increasing lecithin during the six weeks and PG had significant effect in last three weeks of storage time. Lecithin also significantly affected the Fmax, so the cake's with high levels of lecithin in formulation had tender crust, and hardness decreased during the first six weeks of shelf life. No microbial growth was reported in addition of different proportions of hydrocolloids and emulsifiers. Except of lecithin, two other emulsifiers had no significant effect on Chroma index in comparison with control cakes.