Fortification of baked and fried tortilla chips with mechanically expelled soy flour

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2009-05-15

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The effects of the fortification of tortilla chips with mechanically expelled soy flour as well as baking and frying processes on the properties of tortilla chips were evaluated. Sensory characteristics, texture, thickness, color, protein and oil content were evaluated. Texture was measured by objective and subjective tests. Sensory properties were evaluated using a nine point hedonic scale. Soybeans (food grade Hartz) were mechanically expelled to obtain partially defatted soy flour of 6.7% final oil content. Dry masa flour (DMF) was replaced with 0, 10, 20 and 30% mechanically-expelled soy flour (MESF). The equilibrated tortilla was either fried in oil or baked in an air-impingement oven followed by convection oven drying. Overall, fried tortilla chips were harder and thicker than baked tortilla chips. Fried tortilla chips with 20 and 30% soy flour substitution required less force to break. In fried tortilla chips, as MESF increased, force and work levels decreased, where 20% MESF had the lowest force values. Thickness measurements of tortilla chips showed that as the thickness increased, the force and work also increased. Protein increased linearly in baked and fried tortilla chips where 30% resulted in the highest protein level. In fried tortilla chips, MESF fortification increased oil levels linearly as well. Baked tortilla chips were lighter than fried tortilla chips. In a consumer sensory evaluation, fried tortilla chips were preferred more than the baked ones. In fried tortilla chips, 20% had the highest sensory scores overall. Ten and 20% MESF fortification in fried tortilla chips were the most acceptable of all. In all treatments, regardless of type of processing, panelists could not detect any ?beany? flavors in any of the samples. Therefore, dry extrusion followed by mechanical expelling proved successful in creating a suitable soy flour for tortilla chip production. MESF can be added at 10-30% levels in tortilla chips. Up to 20% would be recommended. Frying results in higher acceptability consumer scores over baking.

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