Effects of microwave and ultrasound on the extraction of pectin and its chemical characterisation of banana (Musa sapientum L.) peels

Pectin is a polysaccharide that is widely used as a food additive in food industries. Banana peels that are discarded by vendors after processing bananas for food products contain a high level of pectin. The pectin can be extracted from the plant cell walls whereas the conventional method for extraction would normally take some time to get a high yield. This research was conducted to explore the effects of microwave-assisted extraction (MAE) and ultrasound-assisted extraction (UAE) on the extraction of pectin and its chemical characteristics found in banana peels. For MAE, the effects of microwave power and extraction time on the yield and quality of extracted pectin was studied. It was found that the pectin yield and chemical characteristics increased with the increase of microwave power and extraction time. The percentage yield ranged from 20.93% to 22.91% for microwave power of 300 W for 5-15 mins. The moisture, ash, degree of esterification, methoxyl, and galacturonic content of extracted pectin by MAE had 8.98%, 5.40%, 75.50%, 12.00%, and 57.80%, respectively. For UAE, the effects of temperature and sonication time on the pectin yield and quality of the extracted pectin were also studied. The pectin yields ranged from 1.81% to 3.49% and the moisture, ash, degree of esterification, methoxyl, and galacturonic content of extracted pectin by UAE had 8.00%, 3.39%, 88.83%, 14.50%, and 90.07%, respectively. Although the use of MAE promoted a high pectin yield it had a lower purity level when compared to UAE. Besides, the chemical characteristics of the extracted pectin by UAE is more comparable with commercial citrus pectin than the pectin extracted by MAE.