Optimal conditions for anthocyanins extracting from some food wastes

The aim of this study is to determine the optimum conditions for anthocyanins extracting from the peels of eggplant, onion, red cabbage and pomegranate. The effects of solvent type, ratio of the raw material to solvent, temperature, pH, duration of extraction, and absorbance readings to the range of wavelengths 360-700 nm were examined. For the solvent types, the results showed that the best extraction solvent was ethyl alcohol acidified with citric acid at a concentration of 5% with a pH of 2, followed by ethyl alcohol acidified with hydrochloric acid, then the absolute ethyl alcohol in the third place, and the least was water and acidified water as an extraction solvent. The highest amount of pigment was found in pomegranate peels using ethyl alcohol acidified with citric acid, a value of 76.10 mg 100 g-1 at a wavelength of 390 nm, while the water solvent exhibited the lowest amount extracted pigment of 5.44 mg 100 g-1 at a wavelength of 540 nm in red cabbage peels. The optimum raw/solvent ratio for extraction was 40:1 weight (W)/ volume (V) in onion and eggplant peels with a value of 122.01 and 79.72 mg 100 g-1, respectively, while the ratio of 1:20 (W/V) was the best for extracting both cabbage leaves and pomegranate peels. Temperature results indicated that the highest amount of anthocyanins is extracted at 60 °C for red cabbage, pomegranate and eggplant, with a value of 70.56, 96.21 and 118.43 mg 100 g-1, respectively. On the other hand the temperature of 50°C was the best for extracting onion peels, with pigment amount of 122.01 mg 100 g-1. Finally, the best time duration to extract the pigment is 60 minutes in all raw materials included in the study.