Extraction of pectin from passion fruit peel (Passiflora edulis f. flavicarpa) by microwave-induced heating

Pectin is a heteropolysaccharide obtained from primary cell walls of terrestrial plants, which is a very important raw material for food and pharmaceutical products. Extraction of pectin from the peels of yellow passion fruit (Passiflora edulis f. flavicarpa) under microwave-induced heating was investigated in the present study. Three types of acids (tartaric, acetic and nitric acid) were employed as extracting agents. The effect of extraction time and microwave-power on yield of pectin has been studied using the response surface methodology. The results indicate that exposure time and microwave-power significantly affects the yield of pectin extraction with both nitric and tartaric acids. However, the extractions using acetic acid were significantly affected only by the exposure time. For all scenarios, the highest yields were obtained when the highest levels of power and time were used (628 W and 9 min). Under these conditions, the yield of pectin obtained with nitric and acetic acids were 13 and 12.9% respectively. Tartaric acid emerged as the best extracting agent in terms of yield (18.2%), however, the obtained pectin exhibited low purity and low degree of esterification. Pectin extracted from passion fruit by employing acetic and nitric acid presented better properties: high molar mass (4.625 × 105 for acetic acid and 4.966 × 105 for nitric acid), degree of esterification (64.56% for acetic acid and 64.15% for nitric acid) and content of uronic acids (62.5% for acetic acid and 82.3% for nitric acid).