Innovative superheated steam impingement blanching (SSIB) enhances drying rate and quality attributes of line pepper

Abstract

Blanching is an essential step before processing of agricultural products as it can inactivate enzymes that cause undesirable changes. In current work the effects of superheated steam impingement blanching (SSIB) time and temperature on drying characteristics and red pigments content of line pepper were investigated. Results showed that after a 3-min SSIB pretreatment at 110 °C the pepper epidermis covered with wax coat was damaged. In addition, the drying time was extensively decreased and the loss of red pigments of dried products was reduced. Results showed that the whole drying process took place in the falling rate period, which indicated that diffusion was the dominant physical mechanism governing moisture movement in the samples. Therefore, the second Fick’s law of diffusion was used to determine the effective moisture diffusivity (Deff) of line pepper, which increased from 1.193 × 10−10 to 3.128 × 10−10 m2/s with increasing of the drying temperature and air velocity. The drying activation energy (Ea) of pretreated samples was 34.31 kJ/mol, which decreased by 3% compared with the non-pretreatment group. The findings of this work indicate that SSIB is very promising pretreatment technique as it not only enhances drying process but also improves bioactive substance preservation of red pepper. Keywords: Line pepper, High-humidity hot air impingement blanching, Air impingement drying, Drying characteristics, Quality attributes