Amanda Galvez

Development of a liquid nutritional supplement using a Sesamum indicum L. protein isolate

This work presents some functional properties and the potential use of a new protein isolate from sesame seed flour, Sesaprot® (SP), as protein source in a liquid nutritional supplement. It was compared to a commercial soybean isolate and results showed that its emulsifying properties are better than those of its soybean counterpart. Lysine content is lower than FAO recommendations for children, but is adequate for adults. Other essential amino acids, however, are present in adequate amounts for any kind of consumer. Osmolality, pH and emulsion stability of an experimental formulation were similar to those of commercial beverages. A consumer sensory test indicated that the product was preferred to one prepared with a soybean isolate and to a commercial brand that was assayed.

Real-time and conventional PCR detection of Liberty Link rice varieties and transgenic soy in rice sampled in the Mexican and American retail markets.

Samples of rice from Mexican and USA retail stores were analyzed for the presence of transgenic (GM) events using real-time PCR. In screening for the CaMV35S promoter sequence (35SP), positive results were found in 49 and 35% of the Mexican and American samples, respectively. In further investigations in Mexican samples, 43% were positive for P35S::bar, with two above the quantifiable limit; these were 0.07% and 0.05% GMO. Fourteen out of the sixteen positive samples were labeled as imported from the USA. In testing samples bought in American retail shops, 24% showed positive results, all below the quantifiable range. It could be deduced that P35S::bar positive samples were Liberty Link® (LL) rice. In distinguishing between LL601 and LL62, end-point PCR was used, corroborating the P35S::bar amplicon length difference of these events. LL62 was found in one rice sample purchased in Mexico and two in the USA samples. Its presence was verified with the 35S terminator sequence. All other LL positive samples contained LL601. None of the samples analyzed showed the presence of Bt63 rice. The LL rice varieties found have been identified as not being commercially cultivated, and so their presence requires further investigation. 35SP was also present in samples which did not have any LL rice. Maize sequences could not be detected in any of the samples; however, soybean DNA was found in Mexican and USA rice samples. The Roundup Ready® trait was detected in trace amounts in 16 and 6% of the rice samples bought in Mexico and the USA, respectively. Real-time PCR was shown to be the method of choice for the sensitive and rapid screening of commodities and retail samples for the detection of GM and other contamination.

Survey of aflatoxins in maize tortillas from Mexico City

In Mexico, maize tortillas are consumed on a daily basis, leading to possible aflatoxin exposure. In a survey of 396 2-kg samples, taken over four sampling days in 2006 and 2007 from tortilla shops and supermarkets in Mexico City, aflatoxin levels were quantified by HPLC. In Mexico, the regulatory limit is 12 µg kg−1 total aflatoxins for maize tortillas. In this survey, 17% of tortillas contained aflatoxins at levels of 3–385 µg kg−1 or values below the limit of quantification (12 µg kg−1 and 87% were below the regulatory limit. Average aflatoxin concentrations in 56 contaminated samples were: AFB1 (12.1 µg kg−1); AFB2 (2.7 µg kg−1); AFG1 (64.1 µg kg−1) and AFG2 (3.7 µg kg−1), and total AF (20.3 µg kg−1).

Learning about biosafety in Mexico: between competitiveness and conservation

This article briefly describes the current state of agricultural biotechnology in Mexico, and discusses the countrys main food and agricultural policies implemented in the last decade. Mexicos position in the international biosafety panorama is very complex: it is the only member of the North American Free Trade Agreement (NAFTA) that ratified the Cartagena Protocol on Biosafety and must implement its provisions. Moreover, Mexico is the Centre of Origin and Diversity (COD) of maize, the main staple food of Mesoamerica, and a region of extraordinarily rich biological diversity. The large asymmetries with its NAFTA partners and the need to meet its commercial agreements, put Mexico in a difficult situation with respect to biodiversity conservation. The paper informs about the findings of transgenic maize in Oaxaca as well as the learning needed, and the challenges faced by the Mexican Government in order to implement the appropriate biosafety measures.

Emulsifying Properties of Chemically Deamidated Corn (Zea Mays) Gluten Meal

Corn gluten meal is a by-product of starch production that is readily available. Corn protein isolates have limited applications due to their hydrophobic nature, low solubility and limited functionality as emulsifiers. In this study, a mild acidic treatment of corn gluten meal was performed in order to achieve deamidation of asparagine and glutamine residues and modify the interfacial behavior of this byproduct. A 0.1 N HCl treatment for 6 h at 70 °C rendered a deamidation degree of 20.4%, which increased the emulsification activity index of corn gluten meal from 6.8 to 16.8 m2/g protein, with a remarkable increase in emulsion stability from 0 to 90.6% oil retention. Proteins participating in the emulsion were separated by SDS-PAGE and the main polypeptides were identified as alpha and beta-zeins. After deamidation, protein dissociation and unfolding due to the obtained negative charges resulted in enhanced functionality.

Latin American biosafety regulatory framework

Biotechnology is viewed as a second biological revolution at the turn of the century leading to research applications in various spheres of human activity ranging from farming and health to environmental protection to mining. All these have economic implications. Developing countries, such as the Latin American countries, have problems translating research results into applications leading to products, processes and services. The weak and inherently regulatory policies of these countries mostly promote scientific rather than industrial developments. This paper attempts to give an overview of the biosafety regulations within the framework of biotechnology policies for some Latin American countries such as Argentina, Brazil, Chile and Mexico. The inadequacies of these policies are pointed out and suggestions for future developments in this area are given.