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A puncture test was used to describe the mechanical and textural behavior of crispy‐puffed food extrudates. Four criteria were identified from the force‐time curves: (1) the average puncturing force, Fm, (2) the spatial frequency of structural ruptures, Nwr, (3) the average specific force of structural ruptures, fwr, and (4) the crispness work, Wc. The discriminating power of these criteria was shown through the effects of moisture content and recipe composition in the extrusion‐cooking process. Relationships between puncture criteria were also studied. The effect of water activity showed that the force related criteria described well the mechanical behavior of expanded extrudates.

Two different extraction methods were used for a comparative study of Algerian Myrtle leaf essential oils: solvent-free-microwave-extraction (SFME) and conventional hydrodistillation (HD). Essential oils analyzed by GC and GC-MS presented 51 components constituting 97.71 and 97.39% of the total oils, respectively. Solvent-Free-Microwave-Extract Essential oils SFME-EO were richer in oxygenated compounds. Their major compounds were 1,8-cineole, followed by α-pinene as against α-pinene, followed by 1,8-cineole for HD. Their antimicrobial activity was investigated on 12 microorganisms. The antioxidant activities were studied with the 2,2-diphenyl-1-picrylhydrazyl (DPPH•) radical scavenging method. Generally, both essential oils showed high antimicrobial and weak antioxidant activities. Microstructure analyses were also undertaken on the solid residue of myrtle leaves by Scanning Electronic Microscopy (SEM); it showed that the SFME-cellular structure undergoes significant modifications compared to the conventional HD residual solid. Comparison between hydrodistillation and SFME presented numerous distinctions. Several advantages with SFME were observed: faster kinetics and higher efficiency with similar yields: 0.32% dry basis, in 30 min as against 180 min for HD.

A new texturizing process, Controlled Sudden Decompression (Détente Instantanée Contrôlée "DIC ® "), has been developed to improve the quality of hot-air dried food. The process involves a treatment under high pressure of steam followed by an extremely rapid decompression to the vacuum. Coupled with a drying step, this process provides high-quality finished products for a similar overall cost to hot-air drying alone. The definition, design, and achievement of the appropriate equipment have already been dealt with. In this study, 2 parameters directly related to DIC expansion were examined: initial pressure (before decompression) in the vacuum tank and the decompression duration. Impact of structural modifications on the rate of dehydration was also quantified.

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In order to study the influence of compressed carbon dioxide, over a range of pressures (1.5 to 5.5 MPa) and exposure times (up to 7 h), on the survival of Escherichia coli,Saccharomyces cerevisiae, and Enterococcus faecalis, a new pressurizable reactor system was conceived. Microbial cells were inoculated onto a solid hydrophilic medium and treated at room temperature; their sensitivities to inactivation varied greatly. The CO2 treatment had an enhanced efficiency in cell destruction when the pressure and the duration of exposure were increased. The effects of these parameters on the loss of viability was also studied by response-surface methodology. This study showed that a linear correlation exists between microbial inactivation and CO2 pressure and exposure time, and in it models were proposed which were adequate to predict the experimental values. The end point acidity was measured for all the samples in order to understand the mechanism of microbial inactivation. The pHs of the treated samples did not vary, regardless of the experimental conditions. Other parameters, such as water content and pressure release time, were also investigated.

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