K Nn mK - Amecamex.org.mx

FSB1 – 2004
Food Science and Biotechnology in Developing Countries
four times with tap water to remove excess of lime and lost pericarp tissue. Nixtamal was ground into a
masa using a commercial stone grinder. Masa was mixture with commercial hydrocolloid TC-1 (Gum
Technology Corporation, Tucson, AZ), pressure-molded and extruded into thin circles to make tortillas
1 mm of thick. Tortillas were baked into a gas –fired domestic oven (Hotpoint, 6B4411LO, Leisser S.A.
de C.V., San Luis Potosí, México) for 1 min on each side at ≈250 °C.. After cooling, tortillas were
packed into poly-ethylene bags (20 X 30 cm, Plásticos de México, S.A. de C.V., México) and stored
for 24, 48, 72 and 96 hours at 4°C; after witch the samples were freeze-dried in liquid nitrogen. Stored
tortilla samples were reheated in the gas oven for 30 sec on each side at ≈250 °C, cooled to 30 °C,
then freeze-dried in liquid nitrogen. The variation was introduced to replicate the consumer preparation
of this product. All samples were stored at room temperature in sealed plastic containers.
In vitro digestibility tests: Potentially available starch content was assessed following the enzymic-
colorimetric method of Holm et al. 11 using Termamyl® (Novo A/S, Copenhagen) and amyloglucosidase
(Boehringer, Mannheim). Resistant starch was measured by two different protocols: 1) Retrograded
resistant starch (RRS or RS3) content was measured as starch remnants in dietary fiber residues,
according to the so called "Lund method" as modified by Saura-Calixto et al. 12 , 2) The method
proposed by Goñi et al. 13 was employed to estimate the total amount of indigestible starch (comprising
RS2, RS3 and part of RS1 fractions).
Experimental design and statistical analysis: Data were analyzed using one-way Analysis of
Variance (ANOVA) procedures. Where analysis showed significant differences (p