Peggy Vauchel

Kinetics of ultrasound-assisted extraction of antioxidant polyphenols from food by-products: Extraction and energy consumption optimization

Ultrasound-assisted extraction (UAE) of antioxidant polyphenols from chicory grounds was studied in order to propose a suitable valorization of this food industry by-product. The main parameters influencing the extraction process were identified. A new mathematical model for multi-criteria optimization of UAE was proposed. This kinetic model permitted the following and the prediction of the yield of extracted polyphenols, the antioxidant activity of the obtained extracts and the energy consumption during the extraction process in wide ranges of temperature (20-60°C), ethanol content in the solvent (0-60% (vol.) in ethanol-water mixtures) and ultrasound power (0-100W). After experimental validation of the model, several simulations at different technological restrictions were performed to illustrate the potentiality of the model to find the optimal conditions for obtaining a given yield within minimal process duration or with minimal energy consumption. The advantage of ultrasound assistance was clearly demonstrated both for the reduction of extraction duration and for the reduction of energy consumption.

Impact of energy supply and oxygen transfer on selective lipopeptide production by Bacillus subtilis BBG21

The influence of power dissipation and volumetric oxygen transfer coefficient k(L)a on Bacillus subtilis productivity of lipopeptides surfactin and fengycin was studied in shake flasks in view of scaling-up of this fermentation process. The experiments performed with different flask sizes, relative filling volumes, and shaking frequencies confirmed clearly that lipopeptide production changed in function of power dissipation, via interfacial gas-liquid contact surface and oxygen supply. It was demonstrated that k(L)a is the key parameter controlling the productivity and the selectivity of the bioreaction. Varying the oxygen transfer conditions, the synthesis could be oriented to mixed production or to surfactin mono-production. The fraction of surfactin towards total lipopeptides produced and the maximal surfactin production both increased with k(L)a increase (surfactin concentration about 2 g L(-1) at k(L)a=0.04-0.08 s(-1)), while the maximal fengycin production (fengycin concentration about 0.3 g L(-1)) was obtained at moderate oxygen supply (k(L)a=0.01 s(-1)).

Valorization of Agrifood By-Products by Extracting Valuable Bioactive Compounds Using Green Processes

Abstract One important challenge for the food industry is the exploitation of its by-products as sources of new commodities using ecofriendly technologies with an optimal cost-benefit relationship. In this chapter, an updated overview of the main green technologies used (as pretreatment or during the extraction process) to recover natural products from agrifood by-products is presented: enzyme-assisted extraction, ultrasound-assisted extraction, microwave-assisted extraction, electrically assisted extraction, pressurized-liquid extraction, supercritical-fluid extraction, and instant controlled pressure drop. For each technology, its principle, its advantages, and its limits, especially regarding green extraction principles and examples of its application for valuable biomolecules recovery from agrifood by-products are presented. Then a focus is put on examples of the combination and integration of those green technologies, which enable enhancement of extraction yields and access to enriched natural extracts at reduced time and energy. Finally, future trends for the development of agrifood by-products valorization by green extraction of valuables substances are discussed.

Modeling of twin-screw reactive extrusion: application to alginate extraction

Abstract The context of this study is the mathematical modeling of a reactive extrusion process and its application to alginate extraction from brown algae. In this study, an extension of a dynamical model described by the authors in previous works is proposed. This model is a contribution to build a simulation tool useful for help to the prediction of the time and space evolution of a reaction in a twin-screw co-rotating extruder, that include control parameters (screw speed and flow rate) and geometrical parameters (screw profile and die design). Flow, viscosity and reaction descriptions were coupled in a semi-simplified model where some assumptions that were used to build it are discussed. Some simulations and measurements of residence time distribution, in the specific case of alginate extraction, are then shown.