High Pressure Processing Induced Changes in Bioactive Compounds, Antioxidant Activity, Microbial Safety and Color Attributes of Coriander Paste

Abstract

An attempt was made to quantify the effect of high pressure processing (HPP) (at 50, 200, 400 and 600 MPa) and thermal processing (90 °C) on bioactive compounds and microbial safety of coriander paste. Total soluble solids (TSS) and pH of untreated coriander paste was 7.8 and 6.21°brix, respectively. No significant (α = 0.05) difference was observed in pH or TSS after processing and during storage. Phenolic content increased by 0.99 and 1.10 % when treated at 400 and 600 MPa, respectively. Flavonoid content in high pressure (HP) processed (≥400 MPa) sample was significantly (α = 0.05) higher than thermally processed sample. The untreated coriander paste had ascorbic acid content of 1.32 mg/g which decreased to 1.17 and 0.50 mg/g on HP (600 MPa) and thermal processing, respectively. Chlorophyll a decreased from 1.68 mg/g to 1.58 and 1.21 mg/g in HP (600 MPa) and thermally processed sample, respectively. Complete enzyme [Polyphenol Oxidase (PPO) and Peroxidase (POD)] inactivation was observed after thermal processing, whereas pressure ≥400 MPa required to reduce enzyme activity significantly (α = 0.05). Lightness L* value decreased significantly (α = 0.05) with pressure. Total plate count reduced from 3.0 × 103 CFU/g to zero and 1 × 101 CFU/g in thermally and HP processed (600 MPa) samples, respectively. Storage study (at 4 °C for 45 days) showed that bioactive compounds and antioxidant activity in both thermally and HP processed samples decreased during storage, but this decrease was more severe in thermally processed samples. Thus, study reveals that HPP is more effective at ≥400 MPa, in terms of retention of bioactive compounds, than the thermal processing.