Utilization of Some Fruits and Vegetables By-Products to Produce High Dietary Fiber Jam

Abstract

The present study aimed to investigate the chemical composition, antioxidant activity, total phenolic compounds and ?-carotene of carrot peels, apple pomace, banana peels and mandarin peels and their quality in preparing jam. Mandarin and banana peels characterized by its higher crude fiber (12.16 and 5.25%) and vitamin C (68 and 16.6 mg/100g) compared to carrot peels (3.91%) and apple pomace (3.65%). Banana peels contained higher amount of magnesium, potassium, calcium and iron compared to other peels samples. Therefore, jam of banana peels characterized by its higher content in magnesium (758 mg/100g), potassium (779 mg/100g), calcium (191 mg/100g) and iron (59.15 mg/100g). Jam of apple pomace characterized by its higher phosphorus contents (220 mg/100g) followed by jam of banana peels (138 mg/100g), mandarin peels (128 mg/100g) and carrot peels (53 mg/100g). Jam of carrot peels characterized by its higher phenolics content as gallic acid equivalent (87.4 mg/100g) followed by jams of apple pomace (82.5 mg/100g), banana peels (42.7 mg/100g) and mandarin peels (34.6 mg/100g). The same trend was observed in total flavonoids as catechen equivalent (mg CAT/100g) in jams of carrot peels, apple pomace, banana peels and mandarin peels, where they were 35.9, 30.1, 23.5 and 21.7, respectively. Furthermore, jam of carrot peels had higher antioxidant activity, where its DPPH radical, had lower DPPH based IC50 (1.8 ?g/ml) while jam of apple pomace, banana peels and mandarin peels had higher DPPH based IC50 reached to 2.04, 2.21 and 3.34 µg/ml, respectively. The same trend was observed for the ?-carotene radical in tested jam samples. Hunter color parameter showed that jam of mandarin peels had highest lightness (L* = 39.8), followed by jam of carrot peels (29.46), apple pomace (18.27) and banana peels (15.19). Therefore, jam of banana peels was darker than other tested peels samples. Sensory evaluation showed that jam of apple pomace characterized by its higher taste and odor, followed by jam of mandarin peels, banana peels and carrot peels. Color of tested jam of carrot, banana or mandarin peels was darker than apple pomace jam. Also, jam of apple pomace gave higher scores in appearance and overall acceptability.

Keywords: Jam – Peels – antioxidant activity – Total phenolics– Total Flavonoids