Determination of phenolics and proteins causing sediment formation in pomegranate juice using “Tannase+Lactonase” and “Protease”

Abstract

In this study, pomegranate juice (PJ) was treated with “tannase+lactonase [human-derived (H-PON-1) or rabbit-derived (R-PON-1)]” or “protease [aspartic protease (AP) or cysteine protease (CP)].” After treatment, effects of tannins, proteins and amino acids on sediment formation were determined during storage at 20℃. Among proteins, prolamin showed the highest effect in PJ treated with “tannase+H-PON-1/R-PON-1” and CP. While amino acids did not affect sediment formation in “tannase+H-PON-1/R-PON-1” or AP treatments, only glycine increased sediment content in CP treatment. Removal of galloyl and/or HHDP groups from HHDP-galloyl-glucose-isomer, pedunculagin-2 and punigluconin by “tannase+H-PON-1/R-PON-1” was very effective in preventing sediment formation. Prolamin:galloyl glucose isomer ratio and HHDP-galloyl-hexoside-2 and HHDP-galloyl-glucuronide contents should be 23.244±1.162 and, 1.254±0.063 and 0.679±0.034 mg/L to prevent sediment, respectively. Since common parameters preventing sediment formation in both methods that target removal of tannins and/or proteins were punigluconin content and prolamin:punicalagin-2 ratio, these two parameters must also be considered in sediment-free PJ production.