Alain Largeteau

Effect of ultra-high hydrostatic pressure on hydrosoluble vitamins

The effect of ultra-high hydrostatic pressure on selected hydrosoluble vitamins (B1, B6 and C) is studied. Vitamin retention after pressurization has been compared to that induced by several classic food processing treatments, such as pasteurization or sterilization. Ascorbate, pyridoxal, and thiamin hydrochloride, included in a multivitamin model system (mvMS), are analyzed by high performance liquid chromatography (HPLC), and under current operating parameters for the above processes. Thereafter, these vitamins indicate the impact of ultra-high hydrostatic pressure on the nutritional quality of tested matrices, on the basis of equivalent effects induced by several industrial treatments. Minor variations are found among the vitamins after pressurization. Vitamins B1 and B6 undergo no significant losses after the treatments. Vitamin C levels, although significant, are not dependent on the intensity of the ultra-high hydrostatic pressure process. Naturally occurring vitamin C losses are analyzed in two representative foodstuffs (egg yolk and strawberry coulis) after several processes, in order to validate the model system results. A survey of ascorbate retention has been carried out on ultra-high pressurized strawberry coulis, over 30 days. Results have shown that ultra-high hydrostatic pressure plays only a minor role in degradation kinetics of vitamin C. This article will integrate a general and structured evaluation framework, including other precise nutritional data of food processing.

Changes in aromatic volatile composition of strawberry after high pressure treatment

Abstract The aromatic volatile compounds of high pressure treated strawberry coulis (Fragaria ananassa Gariguette) were analysed by capillary gas chromatography–mass spectrometry (GC–MS) and compared with aromatic volatile compounds of raw strawberry and heat-treated strawberry coulis. Characterisation of treated and untreated samples was achieved by applying principal component analysis to the chromatographic data. Aroma of strawberry was specifically identified by furaneol (2,5-dimethyl-4-hydroxy-furan-3-one) and nerolidol (3,7,11-trimethyl 1,6,10-dodecatrien-3-ol). No significant changes of all the aromatic volatile compounds were observed between untreated and high pressure-treated (200 and 500 MPa, 20°C, 20 min) strawberry coulis. On the other hand, changes appeared in the composition of aromatic compounds after an ultra high hydrostatic pressure treatment at 800 MPa (20 min, 20°C) and after a sterilisation (120°C, 20 min).

Packaging for high‐pressure treatments in the food industry

This study highlights some important aspects of the package, such as packaging materials suitable for high-pressure treatments, package properties (barriers and flexibility) and package integrity. Six different types of package were tested. They consist of multilayer plastic packages (PA/PE), where thickness, permeability and stress varied at yield point and at breakage. They achieve a good heat seal and good protection from the pressure medium (water) surrounding them. Experiments were carried out at 200, 350 and 500 MPa for 30 min at ambient temperature, comparing the performance of pressurized multilayer plastic packages with untreated packages. Different simulants (water, 3% acetic acid, 15% ethyl alcohol and olive oil), in contact with the packages, were used to demonstrate the good integrity between package and foodstuff during treatment and shelf-life. Copyright

Inactivation of Staphylococcus aureus and Salmonella enteritidis in tryptic soy broth and caviar samples by high pressure processing

We studied the action of high pressure processing on the inactivation of two foodborne pathogens, Staphylococcus aureus ATCC 6538 and Salmonella enteritidis ATCC 13076, suspended in a culture medium and inoculated into caviar samples. The baroresistance of the two pathogens in a tryptic soy broth suspension at a concentration of 10(8)-10(9) colony-forming units/ml was tested for continuous and cycled pressurization in the 150- to 550-MPa range and for 15-min treatments at room temperature. The increase of cycle number permitted the reduction of the pressure level able to totally inactivate both microorganisms in the tryptic soy broth suspension, whereas the effect of different procedure times on complete inactivation of the microorganisms inoculated into caviar was similar.

Effects of High Hydrostatic Pressure on Several Sensitive Therapeutic Molecules and a Soft Nanodispersed Drug Delivery System

AbstractPurpose. According to the development in the last decade of industrial processes using high hydrostatic pressure (HHP) for preservation of several commercial food products, novel sterilization or decontamination processes for pharmaceutical products could be conceivable. The aim of this work is to evaluate the effects of HHP on the integrity of insulin and heparin solutions, suspension of monoclonal antibodies and Spherulites®. Methods. High performance liquid chromatography, thin layer chromatography, capillary electrophoresis assays, ELISA tests, laser granulometry and spectrophotometry analyses have been performed to compare HHP treated drugs (in a domain of pressure and temperature ranging respectively from 20 up to 500 MPa and from 20°C up to 37°C) vs. untreated ones. Results. No difference has been detected except for monoclonal antibodies that are altered above 500 MPa. Conclusions. The structure integrity of sensitive molecule due to the small energy involved by HHP and the development of industrial plants (intended for the decontamination of food products) confer to this technology the potential of a new method for sterilization of fragile drugs and an original alternative to aseptic processes and sterilizing filtration.

Inactivation of Staphylococcus aureus using high hydrostatic pressure

The aim of this work was to develop a high-pressure decontamination and sterilization process for pharmaceutical treatments as was developed in food processing in the late eighties. The lack of normalized biological indicators able to validate sterilizing treatments under high pressure led us to select representative pathogenic strains from flora and the European Pharmacopoeia. We selected the following four bacterial strains: Candida albicans (ATCC 10231), Psuedomonas aeruginosa (ATCC 9027), spores of Aspergillus niger (ATCC 16404) and Staphylococcus aureus (ATCC 6538). This present study is focussed on S. aureus. Successive pressurization and depressurization cycles appeared to be more efficient than a continuous high-pressure treatment. Importantly, these pressure conditions, temperature and process duration are perfectly compatible with current industrial plants. These results show that HHP technology is a new alternative to inactivate pathogenic strains in accordance with pharmaceutical requirements.

New packaging solutions for high pressure treatments of food

Abstract High pressure is a promising technology for developing new processes in food treatment. In most cases, pre-packaged foods are used in high pressure treatments (HP). Consequently, the behavior of the package under treatment conditions is an important factor. The following work was devoted to the evaluation of different packages under high pressure conditions in the presence of different substances used as simulants. Three main characterizations were carried out after HP treatment: mechanical resistance, barrier properties and integrity. The experimental results using multilayer plastic films (PA/PE) have led to the selection of several solutions which may be used as packages for high pressure treatments.

Sterilization of Liquid and Semi-Solid Pharmaceutical Forms Using High Pressure Technology

The aim of this study was to investigate the use of HHP (High Hydrostatic Pressure) technology as a possible alternative method for decontamination and sterilization of sensitive drugs. We demonstrated the safety of HHP treatment on several sensitive biomolecules. A 10 min. HHP treatment inactivates totally pure suspensions of P. aeruginosa , C. albicans and spores of A. niger , but S. aureus needs a longer HHP duration treatment to be totally inactivated. Endospores appear to be more baroresistant.

Effect of High-pressure Treatment on Polyphenoloxidase Activity of the Agaricus Bisporus Mushroom

High pressure treatments (100-500 Mpa/4 °C/10 min) were carried out on freshly sliced mushrooms ( Agaricus bisporus ) and on liquid extract. Pressure above 200 MPa led to respiratory activity loss, significant enzymatic browning and polyphenoloxidase (PPO) activation in treated mushrooms. Increasing pressure from 200 to 500 MPa enhanced the PPO activation (in whole tissue and in liquid extract). Stabilization of mushroom by high-pressure (HP) alone cannot be considered. A combination of HP with thermal or chemical treatments is found necessary.

A new route for the synthesis of nitrides: The solvothermal preparation of GaN

Abstract A new solvothermal route for the synthesis of nitrides is proposed using liquid NH3 as solvent in supercritical conditions, Such a preparation method was applied to the synthesis of GaN using gallium metal as starting material. GaN is a wide band-gap semi-conductor (3.4eV). It is a very attractive nitride due to its various applications in micro- and opto-electronics [1,2]. Consequently, many research groups are interested in synthesising GaN. Two methods have been principally developed: (i) synthesis of thin films by epitaxy [3,4] (ii) synthesis of bulk GaN by high pressure method [5,6]. The new proposed process leads to fine microcrystallites of GaN with the wurtzite-type structure. The chemical purity can be optimised versus the synthesis mechanism. The size and shape of the crystallites would be influenced by the nature of the nitriding additive and the thermodynamical conditions (pressure and temperature) used for the synthesis.