Evaluation of physicochemical and functional attributes of whey powder incorporated with pomegranate peel extract

Abstract

A study has been conducted to evaluate the effect of pomegranate peel extract (PPE) (1, 2 and 3%) on physico-chemical and functional attributes of whey powder such as total phenolic content (TPC), flavonoid, proanthocyanidin, alkaloid, antioxidant activity, colour profile, protein-polyphenol interaction, rheology, differential scanning calorimetry (DSC), moisture adsorption isotherm (MAI) and microstructure. The TPC (1.02–27.80 mg/g), flavonoid (1.08–10.93 mg/g), proanthocyanidin (0.62–5.82 mg/g), alkaloid (0.63–2.28%), antioxidant activity (ABTS, 16.61–88.01%; DPPH, 17.02–49.34%), redness (2.33–8.05) and yellowness (27.77–32.24) were increased significantly (P < 0.05) with the increase in PPE. Protein-polyphenol interaction was confirmed with fluorescence spectra, FTIR and SDS-PAGE assays. The protein-polyphenol interaction brought significant changes in exothermic events (103.97–109.61 ºC) and viscosity (0.02–0.11 Pa.s) of the reconstituted whey samples. The DSC (glass transition temperature 77.15–71.37 ºC) and MAI (Equilibrium moisture content 38.75–70.45%) studies revealed that hygroscopic nature of whey powder increased with increase in the PPE. The microstructure analysis revealed that particles combined to form large aggregates upon addition of PPE. The PPE significantly increased the hygroscopicity of the powder and viscosity after reconstitution. These results are useful during drying of PPE added powders as well as polyphenol rich powders.