Dispersive mixing of oil in plasticized starch by extrusion processing to design functional foods
Verlag Dr. Hut, ISBN: 978-3-8439-1112-2, 2013
Zusammenfassung / Abstract:
Health and well–being are the major drivers for the increased interest in functional food products. For this purpose, functional food ingredients that provide health benefits beyond basic nutrition are incorporated into food products. Especially, lipophilic bioactives are of special interest due to their specific health benefits. Key challenge is the delivery of the bioactives through the food product without sacrificing the appeal and convenience character of the food and in a manner that they will indeed promote health and well–being of the consumers. Extrusion processing possesses several advantages due to its multifunctional nature combining several unit operations, which can be manipulated to provide desired product characteristics and functional properties, at the same time. Typically, starch-based foods such as ready–to–eat cereals, pastas, salty and sweet snacks are produced by extrusion processing and are highly appreciated by consumers. For the delivery of lipophilic bioactives through foods, it is mostly favorable to dissolve the lipophilic bioactives in a lipophilic carrier (e.g. triglyceride oil), disperse this solution into small droplets and then microencapsulate these droplets into certain type of matrix to improve their stability, bioavailability and palatability. These can be integrated into the extrusion process by dispersing the bioactives–in–oil solution directly into plasticized starch during extrusion processing, which simplifies the design route by eliminating extra emulsification and microencapsulation steps. However, such a process demands a high degree of understanding of the stability of bioactives and dispersive mixing of lipophilic components during extrusion processing. The objective of this study is therefore to develop a mechanistic insight into the dynamics of dispersive mixing in extrusion processing of plasticized starch with respect to the incorporation of lipophilic bioactives into directly expanded ready–to–eat foods. The research approach utilized is based on first fractionation of the overall goal into logical interrelated sections, which can be investigated more thoroughly and conveniently using various scientific fields, including biochemistry, colloid science, fluid dynamics and rheology. The gained scientific understanding is then used to develop a range of potential solution strategies with respect to the requirements of selected bioactives and the target food product.