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The nutrient composition and toxic factor content of four wild species of Mexican potato were determined to compare the nutritional and toxic potentials with those of a cultivated variety. The nutrient composition did not show wide differences, but the true protein contents of wild species did. As expected, starch was the principal component, free sugars were found in very low levels, and the amylose/amylopectin ratio (20:80 average) did not indicate any special difference between the wild species and the cultivated one. Sulfur amino acids were deficient in all of the samples, and the cultivated species showed the highest chemical score. All of the samples showed low content of lectins and trypsin inhibitors, but two wild species showed >20 TUI/mg. Alkaloids were present in higher quantities in the wild species than in the cultivated one. Keywords: Wild potato; nutrient composition; antinutritional factors; starch; protein quality

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In this work the effect of age and location within the stem on pH and buffering capacity of radiata pine sapwood was investigated. Mature and juvenile wood samples from three different heights in the trunk were obtained from 20, 25, and 30 year-old trees. Aqueous wood extracts from the samples were used to determine the pH and buffering capacity of wood. Results show a significant effect of age and location in the tree, although a strong interaction among all factors was also detected. In general sapwood tended to be more acidic in the lower part of trees, but juvenile wood showed to be more acidic than mature wood. From both type of wood tested, juvenile wood was more sensitive to change its pH and buffering capacity with the height and age. The effect of wood pH and buffering capacity in the manufacture of wood composites is discussed and further research is recommended to determine whether the variations detected in this study can affect the curing of resins and quality of wood base composite manufactured with radiata pine wood.

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