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RESEARCH PRODUCT

Application of HPP in food fermentation processes

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Abstract High pressure processing (HPP) is widely used in the food industry for nonthermal pasteurization of juices, ready-to-eat meals, dairy products, pet food, etc. The pasteurization effect is induced by damaging the membranes of microorganisms (leading to cell lysis) as well as by protein denaturation, thus interrupting cellular functions such as nutrient uptake, DNA replication, etc. Nevertheless, as a thermodynamic variable, pressure can also be used to enhance the fermentative processes if applied at sublethal levels (up to 50/60 MPa) to induce metabolic shifts in microorganisms, This allows accelerating the fermentative processes or even obtaining different compounds resulting from the microorganism response to sublethal hydrostatic pressure. This chapter aims to approach the literature available concerning the potential of fermentation processes under sublethal hydrostatic pressure to obtain food products with different characteristics. The case studies of lactic acid fermentation for yogurt and kefir production as well as malolactic fermentation by Oenococcus oeni will be presented and discussed in more detail. Other biotechnological applications of fermentation processes under pressure will also be presented, namely the adaptation of Saccharomyces cerevisiae to hydrostatic pressure, the fermentation of glycerol by Paracoccus denitrificans and cellulosic material by Clostridium thermocellum for ethanol production, and the cellulose-synthesizing ability of Gluconacetobacter xylinus.