Journal of Food Process Engineering vol:36 pages:470-479
The production of frozen vegetables generally includes a heat treatment (a blanching) to denaturate cellular enzymes. The water used for cooling after this blanching is disinfected to prevent microbial growth and to ensure a microbiologically qualitative end product. In this study the possible influence of the disinfectants chlorine dioxide (ClO2) and peracetic acid (PAA) on the vitamin C content of the processed vegetables was investigated. The vitamin C content was measured using a High Performance Liquid Chromatography (HPLC) technique coupled with a fluorescence detector. Besides a decrease, resulting from the blanching of the vegetables, a concentration dependent effect was seen with peracetic acid. This effect was not noticed when using lower concentrations, e.g. 30 parts per million (ppm) of peracetic acid or 3 ppm chlorine dioxide. The major conclusion of our work is about spinach and we can conclude that it makes no sense to use concentrations higher than 40 ppm of peracetic acid in the cooling water of the blancher since this only results in a supplementary decrease of the vitamin C content and this without a substantial additional anti-microbial effect.