Production of pomegranate fruit leather (pestil) using different hydrocolloid mixtures: An optimization study by mixture design

Pestil (a kind of fruit leather) is a traditional Turkish product generally made from mulberry, grape, and apricot. It is a good alternative for unhealthy candies made from corn syrup and artificial colorant. However, in the traditional processing of pestil, fruit juice (which has 10-14 degrees Bx) and other ingredients (honey, milk, etc.) are boiled in the open vessel to concentrate (40-50 degrees Bx) and starch (approximately 10%) is added to form a gel structure while the concentrate still boiling. As explained, this process is not standardized, and some toxic compounds can be formed during heat treatment. Therefore, this study was conducted to produce a pomegranate pestil from commercial pomegranate juice using xanthan gum (0-4%), locust bean gum (0-10%), and pregelatinized starch (0-10%). D-optimal mixture design was used for the optimization of the pestil formulation. The pestil produced according to experimental design was tested for their water activity, moisture content, color properties, browning index, HMF content, total monomeric anthocyanin, total phenolics, total flavonoids, total proanthocyanidin, antioxidant activity, extensibility, and sensorial properties. According to formulation optimization, the optimum hydrocolloid formula was calculated as 7.5% locust bean gum and 2.5% pregelatinized starch. The pestil produced with optimum formulation had improved properties than traditional pestil. Practical applications Pestil is a stable fruit product, which is consumed throughout the year. It is produced by boiling of fruit pulp or juice added with starch or flour. Process induced toxic compounds can be formed during pestil production since the process is heat involved. Therefore, we optimized formulation using cold gelling hydrocolloids to eliminate heat treatment in pestil production. Healthier product in terms of both phenolics and toxic compounds was produced using optimized formulation.