Degradation kinetics of anthocyanin, flavonoid, and total phenol in bignay (Antidesma bunius) fruit juice during ohmic heating

The effect of ohmic heating on bioactive compounds in bignay (Antidesma bunius) fruit juice during ohmic heating were
evaluated. The parameters measured were total phenol, anthocyanin, flavonoid, and antioxidant activity. Ohmic heating was
conducted at 70, 90, and 110 °C, and samples were collected at heating times of 0, 15, 30, and 45 minutes. Electrical conductivity
of bignay fruit juice increased linearly with temperature with values ranged from 0.012 S/m at 32 °C to 0.039 S/m at 110 °C.
Insignificant change in total phenol was observed, while anthocyanin and flavonoid showed significant degradation and the
degradation kinetics followed the first-order kinetic model. The degradation rate constants for anthocyanin ranged from 0.0016
to 0.0213 min-1 with activation energy (Ea
) of 63.880 kJ/mol and the degradation rate constants for flavonoid were in the range
of 0.0107 to 0.0209 min-1 with activation energy of 18.210 kJ/mol. Antioxidant activities (IC50) obtained from DPPH method
ranged from 0.106-0.168 mg/mL while those obtained from ABTS method ranged from 0.131-0.161 mg/mL. The results indicate
that anthocyanin and total phenol in bignay fruit juice is much more stable during heating compared to flavonoid.