Alain Le-Bail

High pressure thawing of fish and shellfish

Abstract The melting temperature of water is depressed under pressure from 0 °C at atmospheric pressure down to −22 °C at 220 MPa. This property can be used for rapid thawing of foods and maintaining better quality in the thawed product. High pressure thawing of two selected sea foods was evaluated in comparison to thawing in water at atmospheric pressure: aiguillat (Spiny dogfish or Squalus acanthias ) and scallops ( Pecten irradians ). Drip volume from thawing and drip volume from subsequent cooking were measured for this purpose. The influence of the high pressure residence time was also studied. Results showed that for both products, the thawing drip was significantly reduced when thawed under high pressure. Optimal results were obtained at 150 MPa. Total drip including thawing and cooking was higher for scallops and smaller for aiguillat with high pressure thawing in comparison to atmospheric thawing. Increasing the duration of the pressure had a significant effect on reducing the drip volume. These results showed that mass transfer might occur under high pressure between drip and product after thawing was completed.

Phase transition in foods: effect of pressure and methods to assess or control phase transition

Abstract Food systems can be defined as heterogeneous and complex systems in which multiple interactions take place. In addition, food systems are unstable due to chemical and physical reactions. Food components (proteins carbohydrates, lipids, water …) might undergo phase transitions due to a pressure or temperature change. The effect of temperature and pressure on phase transitions of selected food components is discussed with emphasis on high pressure processing of food systems. The possibilities of Nuclear Magnetic Resonance and Magnetic Resonance Imaging in assessing phase transitions in food are highlighted.

The principles of high voltage electric field and its application in food processing : A review

Food processing is a major part of the modern global industry and it will certainly be an important sector of the industry in the future. Several processes for different purposes are involved in food processing aiming at the development of new products by combining and/or transforming raw materials, to the extension of food shelf-life, recovery, exploitation and further use of valuable compounds and many others. During the last century several new food processes have arisen and most of the traditional ones have evolved. The future food factory will require innovative approaches food processing which can combine increased sustainability, efficiency and quality. Herein, the objective of this review is to explore the multiple applications of high voltage electric field (HVEF) and its potentials within the food industry. These applications include processes such as drying, refrigeration, freezing, thawing, extending food shelf- life, and extraction of biocompounds. In addition, the principles, mechanism of action and influence of specific parameters have been discussed comprehensively.

Freezing Combined with Electrical and Magnetic Disturbances

In this chapter, novel freezing methods involving the application of electrical and magnetic disturbances are covered. Freezing is one of the most popular and widely used food preservation methods. The freezing process of food matrices is based on their dominant constituent, which is water. The phase transition of liquid water into ice during the crystallization stage is closely related to the final quality of the frozen product. For this reason, several emerging technologies have been developed to control the crystallization process and to improve the formation as well as the growth of ice crystals. This chapter contains an overview of the theoretical and experimental methods available for the application of static electric, oscillating electric, and magnetic fields related to the freezing process. Understanding the importance of these techniques for improving freezing processes requires analyzing the mechanisms that arise from the findings of these studies.

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.

Methodology assessment on melting and texture properties of spread during ageing and impact of sample size on the representativeness of the results

A large number of methods and instruments have been used for measuring the melting and texture properties of margarine and spread. All these methods assume that margarine or spreads are isotropic materials. Depending on the scale of the sample, such statement is sometimes questionable in particular when using miniaturized samples. This paper gives an overview of the methods adopted and evaluates its suitability to analyze the melting and textural characteristics of spreads. Differential Scanning Calorimetry (DSC) was used to analyze the melting property of spread. Textural evaluation was carried out on spread with cone penetration, creep analysis and compression test using cylinder. DSC was found to be not reproducible due to the small size of the sample; larger sample are recommended. Creep analysis by DMA was found to be a sensitive method in detecting the differences in textural attributes of spread.

Frozen Sangak dough and bread properties: Impact of pre-fermentation and freezing rate

ABSTRACT The impact of pre-fermentation time and freezing rate on Sangak frozen dough and bread quality were studied. The pre-fermented doughs for 0, 30, 60, 90, or 120 min were frozen under –20, –25, or –30°C in air blast freezer. After 24 h storage at –18°C, dough samples were baked after final fermentation. The yeast viability, gassing power, and dough development for fresh and frozen Sangak doughs were determined. Crust color, density, and shear stress of bread obtained from fresh and frozen Sangak dough were evaluated. The results showed that yeast survival initially increased and then decreased with increasing freezing rate. The maximum yeast survival was observed at short pre-fermentation (30 min). A direct relationship was observed between gassing power, dough development, and yeast viability. From bread quality point-of-view, short pre-fermentation and higher freezing rate led to a more desirable bread.

Salt reduction in sheeted dough: A successful technological approach

The challenge of reducing the salt content while maintaining shelf life, stability and acceptability of the products is major for the food industry. In the present study, we implemented processing adjustments to reduce salt content while maintaining the machinability and the saltiness perception of sheeted dough: the homogeneous distribution of a layer of encapsulated salt grains on the dough during the laminating process. During sheeting, for an imposed deformation of 0.67, the final strain remained unchanged around 0.50 for salt reduction below 50%, and then, increased significantly up to 0.53 for a dough without salt. This increase is, in fine, positive regarding the rolling process since the decrease of salt content induces less shrinkage of dough downstream, which is the main feature to be controlled in the process. Moreover, the final strain was negatively correlated to the resistance to extension measured with a texture analyzer, therefore providing a method to evaluate the machinability of the dough. From these results, a salt reduction of 25% was achieved by holding 50% of the salt in the dough recipe to maintain the dough properties and saving 25% as salt grains to create high-salted areas that would enhance the saltiness perception of the dough. The distributor mounted above the rollers of the mill proved to be able to distribute evenly salt grains at a calculated step of the rolling out process. An innovative method based on RX micro-tomography allowed to follow the salt dissolving and to demonstrate the capability of the coatings to delay the salt dissolving and consequently the diffusion of salt within the dough piece. Finally, a ranking test on the salted perception of different samples having either an even distribution of encapsulated salt grains, a single layer of salt grains or a homogeneous distribution of salt, demonstrated that increasing the saltiness perception in salt-reduced food product could be achieved by a technological approach.

Effect of Temperature on the Solubility of CO2 in Bread Dough

Dough expansion during fermentation is caused by CO2 production by yeast, and its transfer from liquid state in the dough liquor to gaseous phase in the gas cells. The liquid-gas equilibrium is controlled by the solubility of CO2 in the dough and by the Henry coefficient. The solubility of CO2 in bread dough was measured for different temperatures with a specific device based on the evolution of the pressure during fermentation at constant volume. The measurements range from 15 to 40°C. Data obtained was extrapolated to 0 and 50°C. Values were found between 1.6 × 10−5 and 5 × 10−6 g CO2 kPa−1 g−1 LPD, at 0 and 50°C, respectively (LPD: Liquid Phase of Dough).

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.