Heat assisted HPP for the inactivation of bacteria, moulds and yeasts spores in foods: Log reductions and mathematical models

Abstract

Food contamination by pathogenic and spoilage spore-formers is a concern. As opposed to sterilization, spores can survive pasteurization processes. Pasteurization of foods require at least 5–6 log reduction of the key pathogenic or spoilage microorganism. Traditional thermal processing at high temperature can achieve this reduction; however, it could diminish food quality. High pressure processing (HPP) is a non-thermal food pasteurization technology used in the food industry, which is able to better retain the natural flavors and nutrients of the foods. For the inactivation of specific spore-formers the combination of HPP with heat is required: high pressure thermal processing (HPTP) or HPP-thermal.The up-to-date knowledge on the effect of HPP and HPTP on the spores of pathogenic and spoilage sporulating microorganisms in low- and high-acidic foods is provided, including the kinetic models used to describe their inactivation in specific foods.HPTP is required for the inactivation of bacterial spores in foods. Certain species of heat-resistant mould ascospores in high-acid fruit juices/purees have comparable resistance to bacterial spores, and also require HPTP. Due to the effects of food type on spore resistances, testing the most resistant spores in specific foods should be carried out before using it as a target/reference for designing new pasteurization processes. Yeasts spores are the least resistant, and susceptible to room temperature HPP. Most of the HPTP inactivation kinetics of bacterial and resistant mould spores showed non-linear trends, thus the resulting pasteurization should be interpreted with more care.