Title

Physio-Chemical and Sensory Properties of a Nutrient-Fortified Extruded Product

Date of Graduation

5-2013

Document Type

Thesis

Degree Name

Master of Science in Food Science (MS)

Degree Level

Graduate

Department

Food Science

Advisor

Navam S. Hettiarachchy

Committee Member

Jean-Francois Meullenet

Second Committee Member

Steve Seideman

Third Committee Member

Pengyin Chen

Keywords

Biological sciences; Extrusion cooking

Abstract

Protein malnutrition is responsible for half the deaths of children under the age of five each year in developing countries. More than 4%, 26%, and 70% of children with protein malnutrition live in Latin America/the Caribbean, Africa, and Asia, respectively. The objective of this research was to develop a novel snack made with millet, black eye bean (from Niger Republic), and rice flour fortified with soybean meal protein using extrusion technology. Proximate analysis of the four flours was carried out to determine their chemical composition. Central composite design (CCD) was used to obtain best extrusion conditions to develop a protein-enriched snack with desirable physio-chemical and sensory properties. The extrusion was conducted following the CCD at varying temperature (190-275 0C) and screw speed (60-110 rpm). Sensory properties were evaluated in terms of color and overall visual acceptability of the extrudates using a nine-point hedonic scale. The results suggested that the two extrusion variables (barrel temperature and screw speed) were found to influence the extrudate physio-chemical and sensory properties both independently and interactively. The extruder barrel temperature was observed to be the most significant factor that affected the extrudate properties. The best extrusion conditions was obtained at a screw speed of 60 rpm and a barrel temperature of 190oC based on expansion ratio, bulk density, water holding capacity, texture, color and overall visual acceptance of the extruded products. This study demonstrated that extruded products which were acceptable to consumers could be prepared from blends of millet, beans, soy and rice flour under a range of extrusion conditions up to 30% of soy flour. This product could be supplied to the developing parts of the world which are prone to protein energy malnutrition especially in Africa. This is the first attempt to produce a soymeal-based enriched protein product with millet and beans from Niger Republic

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