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RESEARCH PRODUCT

Enzyme inactivation and evaluation of physicochemical properties, sugar and phenolic profile changes in cloudy apple juices after high pressure processing, and subsequent refrigerated storage

subject

description

The effect of high pressure processing (HPP) (200–600 MPa/5–45°C/1–15 min) on the enzyme activity and some quality parameters of cloudy apple juice during subsequent storage (4°C for 12 weeks) was investigated. Statistical analysis showed that pressure, temperature, and time had a significant effect (p < 0.05) on tissue enzyme activity, decreasing the activity of polyphenol oxidases (PPO) and peroxidases (POD). No significant changes in physicochemical parameters (pH, total soluble solids, sugars, and vitamin C) were observed after HPP treatments. The main polyphenols detected in apple juice were dichydrochalcones, being phloridzin the predominant (48.8 mg/L), and flavanols, with the highest concentration of (−) epicatechin (20.6 mg/L) followed by (+) catechin (6.4 mg/L) and procyanidin B₁ (1.9 mg/L). Moreover, the application of HPP treatment significantly decreased gallic acid, all flavanols and dichydrochalcones. The storage time significantly affected total polyphenol content (TPC) and selected phenolic compounds, but the most stable were TPC. PRACTICAL APPLICATIONS: This study demonstrated that nutritional quality of cloudy not produced from concentrate apple juice after high pressure processing (HPP) and during subsequent cold storage. HPP significantly influenced on tissue oxidoreductive enzymes decreasing their residual activity below 1 and 33%, respectively, for polyphenol oxidases and peroxidases. The results showed that HPP might be a useful method for preservation apple products, resulting higher color stability due to the inhibition of enzymatic reactions during storage time.