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We determined high pressure processing (HPP) effects on the activities of cathepsins B and D in the muscles of mackerel (Scomber scombrus) and horse mackerel (Trachurus trachurus). In mackerel, the cathepsin B activity decrease reached 40% at 450 MPa while in horse mackerel, low and intermediate pressures (150 and 300 MPa) caused an activity increase (30%) but at 450 MPa a decrease of up to 60%. In both species, cathepsin D activity increased after a 300 MPa treatment (up to 2-fold for mackerel and 60% for horse mackerel) and decreased on a 450 MPa treatment. The activity increase is probably due to HPP damage of lysosome releasing enzymes into the fish muscle. Based on the HPP effects on the activities of cathepsins B and D, 450 MPa may be used to reduce the proteolytic activity of cathepsin B prior to chilled or frozen storage of these fish species. [ABSTRACT FROM AUTHOR]

High pressure processing (HPP) at refrigeration, ambient or moderate heating temperature can inactivate pathogenic and spoilage microorganisms with fewer changes to product “freshness” as compared to conventional food preservation processes. The essential equipment components are here described to help define low and higher cost applications. Specific opportunities are discussed that a food processor can consider to profit from the significant equipment investment required to implement this new processing technology. Although, HPP is the only alternative processing technology that has reached consumers with a variety of new products, there are many pending research questions to be answered to make it a reliable alternative and to have a fundamental understanding of the inactivation of microorganisms and enzymes by pressure. Approaches to generate the knowledge required and the information that is being generated is critically reviewed. [Copyright &y& Elsevier]

Abstract: The current study aimed to develop an inactivation strategy for Clostridium perfringens spores in meat through a combination of spore activation at low pressure (100–200MPa, 7min) and elevated temperature (80°C, 10min); spore germination at high temperatures (55, 60 or 65°C); and inactivation of germinated spores with elevated temperatures (80 and 90°C, 10 and 20min) and high pressure (586MPa, at 23 and 73°C, 10min). Low pressures (100–200MPa) were insufficient to efficiently activate C. perfringens spores for germination. However, C. perfringens spores were efficiently activated with elevated temperature (80°C, 10min), and germinated at temperatures lethal for vegetative cells (≥55°C) when incubated for 60min with a mixture of l-asparagine and KCl (AK) in phosphate buffer (pH 7) and in poultry meat. Inactivation of spores (∼4 decimal reduction) in meat by elevated temperatures (80–90°C for 20min) required a long germination period (55°C for 60min). However, similar inactivation level was reached with shorter germination period (55°C for 15min) when spore contaminated-meat was treated with pressure-assisted thermal processing (568MPa, 73°C, 10min). Therefore, the most efficient strategy to inactivate C. perfringens spores in poultry meat containing 50mM AK consisted: (i) a primary heat treatment (80°C, 10min) to pasteurize and denature the meat proteins and to activate C. perfringens spores for germination; (ii) cooling of the product to 55°C in about 20min and further incubation at 55°C for about 15min for spore germination; and (iii) inactivation of germinated spores by pressure-assisted thermal processing (586MPa at 73°C for 10min). Collectively, this study demonstrates the feasibility of an alternative and novel strategy to inactivate C. perfringens spores in meat products formulated with germinants specific for C. perfringens. [Copyright &y& Elsevier]