PHYSIOCHEMICAL PROPERTIES AND ACE INHIBITORY CAPACITY OF HAZELNUT PROTEIN ISOLATE AND HYDROLYSATES

Abstract

Protein solubility, water holding capacity, fat absorption capacity, emulsion activity index, emulsion stability index, gel formation capacity and Angiotensin-Converting Enzyme (ACE) inhibitory capacity of hazelnut protein isolate (HPI) and its hydrolysate were determined. The results showed that protein solubility had U shape solubility profile with an isoelectric point at pH 4.5-5 and highest value at pH 2 and pH 10.  Water holding capacity and fat absorption capacity of HPI was found as 1.95 mL water/g protein and 2.1 g fat/g protein, respectively. Emulsion activity index and emulsion stability index values were found as 44 m²/g and 46 min at pH 7.0, respectively. Weak gel formation of HPI was seen at 8% and firm gel (LGC) was observed at 12% protein concentration. The concentration of pepsin hydrolysates needed to inhibit 50% of the ACE activity values (IC50) at 0, 30, 60 and 120 min of hydrolysis were 1.47 mg protein/mL, 0.27 mg protein/mL, 0.27 mg protein/mL and 0.26 mg protein/mL respectively. Whereas, IC50 of trypsin hydrolysates at 0, 30, 60 and 120 min were 5.51 mg protein/mL, 0.61 mg protein/mL, 0.56 mg protein/mL and 0.54 mg protein/mL. These results showed that isolates and hydrolysates of hazelnut has valuable functional properties and noted as good candidates for effectively reducing hypertension.