For years, high-pressure processing has been viewed as useful for pasteurizing food while maintaining the quality of fresh food. However, even at moderate pressure, this process is not without effects on food, especially on meat products. These effects are especially important because pressure greater than 400 MPa is generally necessary to achieve efficient microbial inactivation. In this review, recent advances in the understanding of the impacts of high pressure on the overall quality of raw and processed meat are discussed. Many factors, including meat product formulation and processing parameters, can influence the efficiency of high pressure in pasteurizing meat products. It appears that new strategies are applied either (i) to improve the microbial inactivation that results from high pressure while minimizing the adverse effects of high pressure on meat quality or (ii) to take advantage of changes in meat attributes under high pressure. Most of the time, multiple preservation factors or techniques are combined to produce safe, stable, and high-quality food products. Among the new applications of high-pressure techniques for meat and meat-derivative products are their use in combination with temperature manipulation to texturize and pasteurize new meat products simultaneously.

No abstract

No abstract

Yeasts are often exposed to variations in osmotic pressure in their natural environments or in their substrates when used in fermentation industries. Such changes may lead to cell death or activity loss. Although the involvement of the plasma membrane is strongly suspected, the mechanism remains unclear. Here, the integrity and functionality of the yeast plasma membrane at different levels of dehydration and rehydration during an osmotic treatment were assessed using various fluorescent dyes. Flow cytometry and confocal microscopy of cells stained with oxonol, propidium iodide, and lucifer yellow were used to study changes in membrane polarization, permeabilization, and endocytosis, respectively. Cell volume contraction, reversible depolarization, permeabilization, and endovesicle formation were successively observed with increasing levels of osmotic pressure during dehydration. The maximum survival rate was also detected at a specific rehydration level, of 20 MPa, above which cells were strongly permeabilized. Thus, we show that the two steps of an osmotic treatment, dehydration and rehydration, are both involved in the induction of cell death. Permeabilization of the plasma membranes is the critical event related to cell death. It may result from lipidic phase transitions in the membrane and from variations in the area-to-volume ratio during the osmotic treatment.