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
