Recycling of pomegranate peel and mandarin peel with ultrasound assisted solvent extraction

Abstract

According to the data of Food and Agriculture Organization, approximately one third of the food produced in the world (1.6 billion tons/year) is lost when it is not reused at the end of consumption. For the recovery and reuse of valuable ingredients (flavonoids, anthocyanins, phenolic acids) in ‘Katırbaşı’ pomegranate peel and ‘Satsuma’ type mandarin peel, which are food industry wastes, ultrasound assisted extraction method (UAEM) which is green technology was used. The effects of various solvents and particle size on extraction yield were investigated by applying solvent / solid ratio of 5 ml/g , particle size of 0.5-1 mm pomegranate peels and 10 min. extraction time for UAEM. The highest efficiency was achieved by using water with 18%. Total phenolic content (TPC) values are 16.55 mg GAE/g dry peel(dp), 14.4 mg GAE/g dp, 12.55 mg GAE/g dp, 10.9 mg GAE/g dp, 14.45 mg GAE/g dp for distilled water, methanol, 50% methanol-water, ethanol, 70% ethanol-water solvents, respectively, for 0.5-1 mm particle size. TPC was found as 11.75 mg GAE/g dp for particle size of 0.25mm and below and 17.5 mg GAE/g dp for the range of particle size of 1-2 mm using water. Also, similar experiments were made for mandarin peels; TPC and AA (Antioxidant Activity, with DPPH) were determined. The parameters were chosen as different solvent type (water, 100% ethanol, 80% ethanol-water, 100% methanol, 80% methanol-water), extraction time (10 and 20 min.) and solvent/solid ratio (10, 20 ml/g) as well. TPC and AA were found 17.8 mg GAE/g dp and 90% for 100% methanol, 10 minutes and 20 ml/g solvent/solid ratio, respectively. When the ultrasound application time was 20 min, TPC and AA were found 18.24 mg GAE/g dp and 90% for 20 ml/g solvent/solid ratio and 80% methanol, respectively. The highest extraction yield was 19% using distilled water for 20 min, 10 ml/g solvent/solid ratio.