Norma Güemes-Vera

Effect of κ- and λ-Carrageenans as Fat-Replacers in Low-Fat Oaxaca Cheese

A mixture design approach was employed to determine the effect of κ  - and λ-carrageenans of Oaxaca cheese fat reduction on melting (Schreiber and Melt Area), color, protein, moisture, and yielding. Melting was affected mainly by the fat content, but κ  -carrageenan seems to improve this property. Color was affected by fat content, with a relatively profiting effect of λ-carrageenan, related to higher moisture content and higher cheese yielding. Incorporation of low concentrations of carrageenans allowed a considerable fat reduction with no detrimental effect on Oaxaca cheese overall quality.

Enzymatic inactivation and antioxidant properties of blackberry juice after thermoultrasound: Optimization using response surface methodology

The purpose of this research was to optimize the thermoultrasound conditions for blackberry juice using the response surface methodology and considering juice quality parameters and antioxidant capacity. With the exception of microbial growth, the response variables showed high correlation coefficients with the mathematical model (R2adj>0.91). Thermoultrasound treatment inactivated all the evaluated microorganisms, and at the optimum conditions (50±1°C at 17±1min) it increased enzyme inactivation and antioxidant activity in comparison to pasteurized juice. The results demonstrated that thermoultrasound can be an alternative to pasteurization for the production of safe and high-quality juices with the added value of higher concentration of bioactive compounds and antioxidant capacity.

Application of Ultrasound in a Closed System: Optimum Condition for Antioxidants Extraction of Blackberry (Rubus fructicosus) Residues

Blackberry processing generates up to 20% of residues composed mainly of peel, seeds and pulp that are abundant in flavonoids. The objective of this study was to optimize the ultrasound conditions, in a closed system, for antioxidants extraction, using the response surface methodology. Blackberry (Rubus fructicosus) residues were analyzed for total phenolics, total anthocyanins, and antioxidant activity by ABTS and DPPH. The selected independent variables were ultrasound amplitude (X1: 80%–90%) and extraction time (X2: 10–15 min), and results were compared with conventional extraction methods. The optimal conditions for antioxidants extraction were 91% amplitude for 15 min. The results for total phenolic content and anthocyanins and antioxidant activity by ABTS and DPPH were of 1201.23 mg gallic acid equivalent (GAE)/100 g dry weight basis (dw); 379.12 mg/100 g·dw; 6318.98 µmol Trolox equivalent (TE)/100 g·dw and 9617.22 µmol TE/100 g·dw, respectively. Compared to solvent extraction methods (water and ethanol), ultrasound achieved higher extraction of all compounds except for anthocyanins. The results obtained demonstrated that ultrasound is an alternative to improve extraction yield of antioxidants from fruit residues such as blackberry.

Physicochemical Characterization of Regional Breads Produced in the Northern Mountains of Puebla State, Mexico

Water exists in foods in free and bound forms; only unbound water is available for microbial growth and biochemical reactions (Prior 1979; Troller 1980). Measurement of unbound water is termed water activity (A w ) and is defined as the ratio of partial vapor pressure of water in the air to the vapor pressure of water vapor in saturated air at the same temperature (Scott 1957). This measurement is numerically equal to the relative humidity at equilibrium expressed as a fraction. Techniques for measurement of A w have been reviewed by Prior (1979) and Troller and Christian (1978). In addition, two collaborative studies have compared the various methods (Labuza et al. 1976; Stoloff 1978). Bread is one of the oldest food products consumed by humans. There is clear evidence of its use by different civilizations since prehistoric times. Bread has been a popular product because of its nutritious properties, and this product uses common ingredients as salt, sugar, and yeast (Serna 1996). Bread is a basic food made with cereals, usually in the form of flour, and liquid means, usually water. One of the greatest differences in bread production is the addition of leavening. Bread can be identified by very different names according to its form, weight, color, texture, etc., and the way in which it is presented in different countries as well as in different localities. In Mexico, baking product consumption is high, where approximately 750 varieties of sweet bread exist (CANAIMPA 2007).