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FSB1 – 2004
Food Science and Biotechnology in Developing Countries
“retrogradation”, greatly influences the texture and shelf-life of these products 3 . The tortillas have a
problem, because after preparation staling ocurrs increasing rigidity which affects palatability. On the
other hand, starch retrogradation increases enzymatic resistance to starch digestion due to the
formation of resistant starch wich is associate with low glycaemic and insulinemic responses and is
very important for prevention of some diseases as colonrectal cancer, low blood cholesterol, decresed
of coronary infart. Hydrocolloids are normally added to bakery products to improve shelf life by
retaining more moisture and retarding staling 4 ; however, adding hydrocolloids to bakery products to
reduce staling also affects processing and product qualities 5 . It has been reported that adding
hydrocolloids in tortillas enhance the flexibility and strenght, reduce stickiness during process and
packing, increase postbake moisture levels, slow the staling process, and extend shelf life 6,7,8 ;
however, interactions between starch and hydrocolloids may ocurrs in tortillas containing these
additives which might decrease starch digestibility. Good quality corn tortillas are soft and can be
rolled into “taco” from without damage. The textural characteristics of tortillas are related to the binding
forms and the amount of water contained. The fresh masa is highly susceptible to lose moisture which
makes its texture hard and therefore difficult to shape into round flat form 7 . A dehydrated corn masa
produce hard and breakable tortillas. Thus, retention of water in masa and tortilla is important since
excessive water loss makes an unacceptable product. The nixtamalization process produces changes
that improve the nutritional quality of tortillas. Many studies have been conducted on nutritional
aspects of nixtamalized maize in relation with protein, minerals and lipids, but very few studies have
been carried out on the digestibility of its carbohydrate constituents 9,10 , and there are not studies on
starch digestibility in tortillas mixed with hydrocolloid and the mechanims involved in these perceived
phenomenon. The objective of the present study was to evaluate the influence of the commercial
hydrocolloid TC-1 on the resistant starch content in tortilla.
MATERIALS AND METHODS
Sample preparation: The traditional method to produce nixtamal, masa and tortillas was used.
Sample lots of 5 kg maize (commercial white dent maize grown in the state of Guerrero, México) were
cooked in 15 L of lime solution. Lime is added at 1 % (grain weight basis). Maize was cooked for 1 h at
boiling temperature, steeped in the same cooking vessel for 16 h, and then the cooking solution
(called nejayote) was discarded. The cooked-steeped maize (called nixtamal) was washed three or