Marie de Lamballerie

Effect of high pressure and salt on pork meat quality and microstructure.

The interaction of salt (0%, 1.5%, and 3% in the final product) and a high-pressure treatment (500 MPa, 20 °C, 6 min) was investigated using pork biceps femoris muscle. The Warner-Bratzler shear force and the water holding capacity (WHC) were assessed and linked to the microstructure evaluation by environmental scanning electronic microscopy (ESEM). Pressure-treated and cooked samples showed a high Warner-Bratzler shear force with a low WHC compared to control cooked samples. These negative effects could be linked to the general shrinkage of the structure as observed by ESEM. The addition of 1.5% salt was sufficient to improve the technological properties of the high-pressure-treated samples and to counteract the negative effect of high pressure on texture and WHC. This phenomenon could be linked to the breakdown in structure observed by ESEM. This study states that it is possible to produce pressurized pork products of good eating quality by adding limited salt levels.

Dynamic proteome changes in Campylobacter jejuni 81-176 after high pressure shock and subsequent recovery

Campylobacter jejuni is one of the most intriguing human foodborne bacterial pathogen. Its survival throughout the food processing chain and its pathogenesis mechanisms in humans remain enigmatic. Living in the animal guts and particularly in avian intestine as a commensal bacterium, this microorganism is frequently isolated from meat products. Ultra high pressure (HP) is a promising alternative to thermal technology for microbial safety of foodstuffs with less organoleptic and nutritional alterations. Its application could be extended to meat products potentially contaminated by C. jejuni. To evaluate the response of Campylobacter to this technological stress and subsequent recovery at a molecular level, a dynamic 2-DE-based proteomic approach has been implemented. After cultivation, C. jejuni cells were conditioned in a high-pressure chamber and transferred to fresh medium for recovery. The protein abundance dynamics at the proteome scale were analyzed by 2-DE during the cellular process of cell injury and recovery. Monitoring protein abundance through time unraveled the basic metabolisms involved in this cellular process. The significance of the proteome evolution modulated by HP and subsequent recovery is discussed in the context of a specific cellular response to stress and recovery of C. jejuni with 69 spots showing significant changes through time.

Interlocking of β-carotene in beta-lactoglobulin aggregates produced under high pressure.

Vitamin A deficiency is one of the major causes of mortality and morbidity in the developing World. This deficiency can be prevented by alimentary or pharmaceutical supplementation. However, both vitamin A oxidation and isomerization should be prevented, as these phenomenons result in loss of nutritional efficacy. The aim of this study was to investigate the effect of a food protein matrix, β-lactoglobulin (β-Lg) aggregates produced by high pressure (HP), on the stabilization of β-carotene during storage and gastro-duodenal digestion and therefore on its bioavailability. In vitro gastro-duodenal digestion of β-Lg aggregates entrapping β-carotene showed that up to 12% and 33% of total β-carotene was released after peptic and pancreatic digestion, respectively. Overall, our study showed that β-Lg aggregates are efficient for caging and stabilization of β-carotene during storage and digestion. Hence, it may be an interesting approach for the protection and the delivery of vitamin A.

Proteins involved in Campylobacter jejuni 81-176 recovery after high-pressure treatment.

Campylobacteriosis has been recognized as the major bacterial food‐borne infection worldwide. Campylobacter, especially C. jejuni, contaminate mainly poultry meat. Although more sensitive than other food‐borne pathogens to many stresses, C. jejuni can survive food processing and go on to reach its final reservoir (the human gut). Genomic analyses of this organism indicate a lack of genes described in other gram‐negative bacteria to overcome stresses. The high‐pressure recovery response of C. jejuni 81–176 was analyzed from two‐dimensional electrophoretic profiles of the cytoplasmic proteome. The main cellular mechanisms controlling the down‐ and upregulated proteins are discussed.

Pasting properties of high-pressure-treated starch suspensions

High pressure (HP) applied to starch suspensions is a promising technology as an alternative to conventional thermal treatment. It may allow the development of new textures which may retain flavors and nutrients while providing food safety. The properties of corn starch and two waxy starch suspensions, rice and corn, were studied after or during HP treatments at 500 MPa. Waxy starches lost their granular structure during the pressure treatment, whereas corn starch granules swelled gradually. Waxy rice starch was the more pressure sensitive among the studied starches. After 10 min at 500 MPa, the granular structure disappeared totally and the gel obtained reached its maximal viscosity. It was more viscous than the two corn starch suspensions. Viscosity of both corn starch gels increased gradually during 30 min at 500 MPa, but waxy starch gave the more viscous gels. This study demonstrates the high potential of waxy starches for HP applications in food.

Effect of high pressure treatment on the characteristics of a model emulsion

The aim of this study was to investigate the use of HP (high pressure) technology as a possible alternative method for decontamination of non-food medium. HP (500 MPa) did not modify significantly the physicochemical characteristics of a model non-food emulsion. A 10 min HP treatment inactivated totally Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Aspergillus niger and Candida albicans even if all the five microorganisms were inoculated together, regardless of the initial load. No recovery was observed until six months of storage at 25°C.

High-Pressure Processing of Meats and Seafood

Meat and seafood products represent a high proportion of the applications of high-pressure processing (HPP) in the world. Mainly used for decontamination purposes, this innovative process has proved to be a reliable technology for ensuring food safety and extending the shelf life of these perishable and fragile foods. However, meat and seafood may experience quality alterations under pressure. This chapter focuses on the effect of HPP on meat and seafood organoleptic quality (texture, color, aroma, taste…). The physicochemical processes responsible for these changes are also reviewed to provide a better understanding of the mechanisms involved. This chapter ends with an overview of current commercial applications and other potential applications.

Effect of high pressure–high temperature process on meat product quality

High pressure/high temperature (HPHT) processing is an innovative way to sterilize food and has been proposed as an alternative to conventional retorting. By using elevated temperatures and adiabatic compression, it allows the inactivation of vegetative microorganisms and pathogen spores. Even though the microbial inactivation has been widely studied, the effect of such process on sensorial attributes of food products, especially meat products, remains rare. The aim of this study was to investigate the potential of using HPHT process (500 MPa/115 °C) instead of conventional retorting to stabilize Toulouse sausages while retaining high organoleptic quality. The measurements of texture, color, water-holding capacity and microbial stability were investigated. It was possible to manufacture stable products at 500 MPa/115 °C/30 min. However, in these conditions, no improvement of the quality was found compared with conventional retorting.

Modifications of protein-related compounds of beef minced meat treated by high pressure

In this study, we evaluated the modifications of the protein-related compounds of minced beef treated with high pressure, including refrigeration after treatment. The free amino acid content, protein carbonyls and free thiol groups were assessed. High pressure up to 200 MPa had a significant effect. Above 300 MPa, irreversible structural changes occurred, with an increase in the protein oxidation products and a modification of the amounts of amino acids after 14 days of storage. Protein carbonyls and the free thiols were correlated with the free amino acids. These results showed that protein modifications under pressure result from both conformational and chemical changes, possibly associated with lipid changes under high-pressure treatment.

Gelatinization kinetic of waxy starches under pressure according to ionic strength

High pressure is a potential technology for the texturization of food products at ambient temperature. In this area, waxy starches are particularly interesting because they gelatinize quickly under sufficient pressure. However, gelatinization may be influenced by other components in the food matrix. Here, we investigate the influence of increasing ionic strength on gelatinization rate and kinetics at 500 MPa for waxy corn and waxy rice starches. We show that increasing ionic strength strongly retards and inhibits starch gelatinization under pressure and leads to heterogeneous gels with remnant granules.