A new enzymatic clarification method for pomegranate juice: Removal of defects and improvement of quality by tannase, lactonase and papain

Abstract

Effects of clarification with “tannase,” “tannase+lactonase,” “papain,” “aspartic protease” and “tannase+lactonase+papain” on defects (turbidity, sediment and color loss) and important constituents (phenolics, anthocyanins, proteins and amino acids) of pomegranate juice (PJ) were investigated. Lactonase [human-derived (H-PON-1 and H-PON-2) and rabbit-derived (R-PON-1, R-PON-2 and R-PON-3)] was used during juice clarification for the first time. Phenolics and amino acids were quantified by HPLC-DAD-MS and HPLC. After clarifications with “tannase (1 g/L)+R-PON-1 (0.33 mg/L)” and “tannase (1 g/L)+R-PON-1 (0.33 mg/L)+papain (10 mg/L)” at 30℃ for 90 min, sediment was completely eliminated during storage at 20℃ for a month. Among these treatments, “tannase+R-PON-1” provided the lowest turbidity formation rate. The most effective parameter to prevent sediment was the ratio of “prolamin to trigalloyl-HHDP-glucose-isomer-2” that should be ≥205.4 (r=–1.000). Moreover, “tannase+R-PON-1” caused 4.3 times lower turbidity than control group after storage. To retain low turbidity (≤10 NTU) during storage, galloyl-glucose-isomer and HHDP-galloyl-hexoside-3 should completely be removed from PJ and, punigluconin and trigalloyl-HHDP-glucose-isomer-2 contents should be ≤0.19 and ≤0.04 mg/L, respectively. Furthermore, “tannase+R-PON-1” provided a significant contribution to anthocyanin copigmentation. The most effective copigments in PJ were HHDP-galloyl-glucuronide, punigluconin, punicalagin-2, punicalagin-3, aspartic acid, glutamic acid and alanine. “Tannase+R-PON-1” is recommended to produce a high-quality PJ.