Changes in the physicochemical properties, aromas and polyphenols of not from concentrate (NFC) apple juice during production

Abstract

The effects of unit operations on the quality of not fromconcentrate (NFC) apple juice were investigated in this study. After the main processing steps (juicing, pre-pasteurization, homogenization and pasteurization), juice samples were collected and characterized by total soluble solid (TSS), titratable acidity (TA), pH, turbidity, non-enzymatic browning index (NEBI), color quality, aromas and phenolic constituents. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) were applied for analyzing juice aromas and polyphenols. The results showed that homogenization only affected (increased) the juice turbidity, and only the TSS content was not affected by the unit operations. The TA, pH, aroma component and polyphenol content of the NFC apple juice were significantly decreased, while the turbidity, NEBI and color values were significantly increased by pre-pasteurization. Pasteurization had less effect on these properties than pre-pasteurization. Therefore, those were the thermal treatments that mainly affected the juice quality during NFC apple juice production.