K Nn mK - Amecamex.org.mx

Physical-chemical analysis: Moisture content, ash, fat, non digestible fibre and pH
were determined by AOAC methods (1991). Brut Protein by MicroKjieldal method,
and True protein by Bradford method, minerals by Plasma emission spectrometry
(Thermo Jarrel Ash) and density by picnometry. Water activity and sorption isotherm
were performed using Aqualab serie 3,
Tejate drying. The tejate was dried in a cabinet drier at 70C and 1-1.5 m/s of air
velocity for 4 h. The thickness of the tejate layer was 0.5 cm. The dried product was
grounded and sieved to obtain particle size smaller than 500 mm (Mendoza, 2004).
Tejate preparation. 1 kg of white corn, 100 g of cocoa, 20 g of Rosita de cacao, 20 g
of mamme sapote seeds, 3 L of water and 250 g of lime were used for tejate
preparation (Cortes, 1999). The corn was cooked with lime during 2 h, then it was
washed and mixed with the other ingredients previously roasted. The mixture was
grounded until an homogeneous dough was obtained.
Sensory test. Optimal concentration of dried tejate, sucrose and water were
determined and a consumer preference test was performed to compare fresh and
dried tejate.
RESULTS AND DISCUSION
1.- Microbiologic analysis. Results of the sampling in the Oaxaca Central Valleys
markets show that 9 samples had for E. coli (table 1). The E. coli presence is mainly
due to fecal contamination and it is a risk indicator of the presence of other
pathogens. In some cases, the water used for the preparation of tejate drink was
contaminated; salmonella was present in 4 samples. There is a lack of sanitary
control in the markets of Oaxaca City, 8 of the 9 samples were contaminated with E.
coli. The dried tejate samples were negative for the entire microbiological tests
performed (table 2).
2.- Chemical composition. As shown in table 3, the tejate is a drink basically
energetic, with few quantities of protein and fat. It contains 10 minerals (table 4). A
serving of tejate contributes, 60% phosphorous, 75% magnesium and, 16% zinc of
children RDA.
3.- Physical characteristics. Results on the physical characteristics are the same
for both, fresh and dried tejate. Density was 1.046 g/cm 3 and 1.057 g/cm 3 , pH 7.43
and 7.47, for fresh and dried drink tejate respectively. It is slightly alkaline due to the
lime added for corn cooking. The solubility of tejate powder was 14 g/100 ml.
4.- Drying and sorption behavior. Figure 1 shows the drying kinetics of tejate paste
at 70C. Its high starch content partially gelatinized, had extended the time of tejate
drying; 2 h after drying started, only 50% of water had been eliminated. The
composition presented the same effect in the desorption isotherm (fig. 2).