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Vitamin C in Blanched Vegetables: Effect of Chlorine Dioxide and Peracetic Acid Used as Disinfectants during Cooling

Abstract

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 PAA. This effect was not noticed when using lower concentrations, e.g., 30 parts per million (ppm) of PAA 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 PAA 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 antimicrobial effect.

Practical Applications

This work clearly demonstrates that disinfection with chlorine dioxide or PAA of the water used for cooling blanched vegetables, does not affect the vitamin C content of the frozen vegetables on condition that the concentration of the disinfectant is not too large. If a larger concentration is used, then the microbial quality of the vegetables will not improve, but there will be additional breakdown of vitamin C. For spinach, this safe concentration limit of disinfectant is about 40 ppm for PAA or 3 ppm for chlorine dioxide. For snap beans, carrots and sprouts the “safe” PAA concentrations, which will not provoke additional vitamin C breakdown are respectively 50, 40 and 30 ppm.

Authors:   Etienne Jooken, Annelies Smedts, Evelyn Desmidt, Annick Monballiu, Ruis Amery, Boudewijn Meesschaert
Journal:   Journal of Food Process Engineering
Year:   2013
Pages:   n/a
DOI:   10.1111/jfpe.12009
Publication date:   07-Mar-2013
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