PhD Oral Defense of Ashutosh Singh, Department of Bioresource Engineering
Food and its constituents are subjected to various processing techniques including, thermal, mechanical, chemical, extraction, extrusion, high pressure, high electric field and irradiation. Some of these techniques are used to either improve their shelf life (e.g. heating, pasteurization) by removing or inactivating microbes and toxins, extract valuable compounds (e.g. isolation, purification, oil extraction) or modify their properties (gelling, foaming, improving digestibility) to derive large varieties of additional food products (e.g. bread, yogurt, beverages). These processing methods can be categorized as thermal or non-thermal. The thermal techniques process food by subjecting them to high temperature, e.g. roasting, frying, drying etc.; these techniques have both positive (improvement in texture, color, taste etc.) and negative (generation of acrylamide through Maillard reaction, loss of nutritional value etc.) effects. Non-thermal methods (high-pressure, electric field treatment, irradiation etc.) have been developed to combat these disadvantages of thermal processes.
Proteins, which are one of the most important macromolecular constituent of food are very sensitive to external stresses, arising from the aforementioned processing sources. Studies have shown that under the influence of external stress proteins undergo structural and conformational changes, which impacts its functionality. Some food proteins including wheat gluten, egg proteins, milk proteins etc. are involved in patho-physiology of several allergic reactions. The relation between external stresses and food protein functionality is well known at a macro level but the mechanisms involved at the atomistic and molecular level are not well known.
In this study, we have designed and developed an apparatus for investigating non-thermal Electrohydrodynamic (EHD) drying technique in which an electric wind generated from a charged electrode is used to enhance the drying of a hygroscopic or non hygroscopic sample under ambient conditions.