Influences of AC frequency and electric field strength on changes in bioactive compounds in Ohmic heating of pomelo juice

Abstract

Abstract Ohmic heating (OH) is a direct heating method that generates uniform, fast heating and increases the inactivation of bacteria and enzymes in pomelo juice in a shorter duration and at a lower temperature than those used in conventional heating (CH). This study investigated the influence of frequency and electric field strength during OH on the chemical parameters and bioactive compound content of pomelo juice, including ascorbic acid (AA), citric acid (CA), naringin, limonin, total polyphenol content (TPC), and antioxidant capacity. The frequency significantly influenced the degradation of AA, which determines the antioxidant activity. Electric field strength caused a significant decrease in AA, TPC, and antioxidant activity at low electric field strength (20\xa0V/cm). The compound degradation was similar for OH at 30\xa0V/cm and 60\xa0Hz and CH. This means that the electric field did not affect the degradation of these compounds during OH if the juice was heated at those approximate parameters. OH may therefore be proposed as an effective method of pasteurizing pomelo juice.