Bound phenolic acids were isolated

Bound phenolic acids were isolated according to the method of Krygier, Sosulski, and Hogge (1982) with some modifications. Mango peel dietary fibre (2 g) was hydrolyzed with 1 M sodium hydroxide containing 0.5% sodium borohydride under nitrogen atmosphere. The hydrolysate was acidified to pH 2 with 4 M HCl and centrifuged. Total polyphenol content was determined by the method of Swain and Hillis (1959) and gallic acid was used as a standard. Flavonoid content was determined by the method described by Heimler, Vignolini, Dini, and Romani (2005) and (+) catechin was used as a standard. Phenolic acids and flavonoids were identified by HPLC