Development of a functional food ingredient using extrusion processing technology : a thesis presented in partial fulfillment of the requirements for the degree of Master of Technology in Food Technology at Massey University
This project aimed to develop a puffed "functional food" cereal ingredient that could subsequently be used in muesli bar products and potentially be on sold to breakfast cereal manufacturers. This ingredient was to contain nutrients that provided heart health benefits and also to possess good textural properties and to have an acceptable taste. Extrusion processing was used to produce the ingredient; extrusion processing transformed the raw materials used into a more palatable and texturally acceptable form and changed the nutritional quality. The decision as to which nutrients to include in the ingredient required consideration of efficacy, regulatory and consumer and market factors. A literature review was undertaken to identify potential nutrients that would have heart health efficacy, meet regulatory guidelines and still be acceptable to consumers. A qualitative consumer study was conducted to gauge consumer awareness of the nutrients investigated and the desirability for these ingredients to be included in a bar benefiting heart health. The main heart health nutrient selected for use in the puffed muesli ingredient, based on the results of screening, was soluble fibre. The source of soluble fibre selected was oat. The total, soluble and β-glucan (a particular form of soluble fibre) dietary fibre contents and the physical properties were of interest due to their influence on heart health benefits, product claims and sensory characteristics. The effect of formulation (starch level, starch type), enzyme treatment and extruder processing settings on the fibre content and physical properties of the puffed ingredient was investigated. It was found that soluble fibre increased during the extrusion process, partially at the expense of insoluble dietary fibre. However, β-glucan was found to decrease during processing. The level of starch in the formulation was found to have the most significant effect on both the physical and nutritional properties. Increasing the level of starch had a positive effect on the physical properties, but decreased dietary fibre levels. The puffed extrusion product contained a low level of β-glucan and a moderate level of total and soluble dietary fibre. A number of recommendations are presented concerning the feasibility of commercialisation, ingredient supplementation requirements and further research associated with the optimisation of the formulation and extrusion processing conditions.