Varietal Influence on Phenolic Constituents and Nutritive Characteristics of Pomace Obtained from Apples Grown in Western Himalayas

Apple fruit processing is not variety specific in India, which affect the overall quality of the final processed product. The present study was aimed at elucidation of the nutritive value, phenolic content, antioxidant activity and bioactive phenolic constituents of five widely used apple varieties (Royal Delicious, Red Delicious, Golden Delicious, Red Chief and Red Gold) of western Himalayas. The pomace obtained from different varieties was evaluated to assess the fruit quality. Royal Delicious pomace had significantly high ( < 0.05) total dietary fibre content (42.63 ± 1.26%) together with soluble (8.25 ± 0.95%) and insoluble fibre (32.90 ± 0.89%), as compared to other apple varieties. The pomace samples were extracted with 70% aqueous methanol to obtain polyphenol enriched extracts. The results of Folin-Ciocalteau assay showed that hydroalcoholic extract of Royal Delicious pomace exhibit higher phenolic content as compared to other varieties and ranged between 2.19 ± 0.09 and 4.59 ± 0.47 mg GAE/g. Royal Delicious pomace also possess higher antioxidant capacity i.e. 3.35 ± 0.10 mg/g, 2.71 ± 0.10 mg/g and 4.67 ± 0.03 mg/g as measured by DPPH, ABTS free radical scavenging assay and FRAP reducing assay, respectively. The higher phenolic content in Royal Delicious pomace was also confirmed by RP-HPLC-DAD analysis. Results of HPLC analysis revealed the presence of phloridzin (487.07 ± 0.04 µg/g), quercetin (241.18 ± 0.03 µg/g), quercitrin (178.34 ± 0.02 µg/g) and quercetin-3-glucoside (195.21 ± 0.05 µg/g) as major constituents. Present results indicate that Royal Delicious variety is rich in dietary fibre and phenolic compounds that might be used by the food sector as a source of bioactive health promoting constituents/dietary supplements.