BACKGROUND: Blackberries (Rubus spp.) are fruits rich in secondary components (anthocyanins, proanthocyanidins, phenolic acids, carotenoids and others), recognized for their health benefits. OBJECTIVE: To evaluate the content of different types of phenolic compounds and their antioxidant activity in several extracts of three varieties of blackberry fruit (Rubus adenotrichos) (red thorned, thornless and sweet), using different blackberry standards. METHODS:The varieties of blackberry fruit were analyzed in three stages of maturation (green, red and black). The evaluation of the phenolic compounds was carried out by applying commercial standards and own standards to the same samples, following the Folin-Ciocalteu, differential pH, DMAC, and ORAC procedures. RESULTS:The red thorned variety presented the best results with a concentration of polyphenols of 183.0 ± 0.5 mg GAE/g DS, antioxidant capacity of 3322 ± 10 mol TEAC/g DS, a value of 15.4 ± 0.3 mg of cyanidin-3-glucoside eq/g DS of anthocyanins, and a value of 9.26 ± 0.03 mg 4´-O-methylgallocatechin eq/g DS for of proanthocyanidin content. CONCLUSIONS: Our results show the limitation of a currently used standard, gallic acid and 4´-O-methylgallocatechin, for quantification of total polyphenols and proanthocyanidin respectively, and outline the development and validation of a more robust and accurate standard for blackberry fruit analysis.

The cultivation of native corn has decreased in favor of the cultivation of improved commercial corn varieties. This study seeks to evaluate the antioxidant and antibacterial potential of 36 samples of native corn germplasm from the Brunca (BR) and Chorotega (CR) regions of Costa Rica. The main parameters of comparison were the composition of antioxidant compounds, antiradical activity, and microbicidal effect. The total amount of polyphenols in the germplasm (120 mg GAE/100 g d.w.) was not related to the regions from which the samples were obtained. The overall average for antioxidant capacity was 21.20 μmol TE/g d.w. Accessions from the CR region had higher antioxidant capacity. Anthocyanin content was higher in purple accessions and undetectable in white germplasm. Antioxidant capacity was statistically related to polyphenols content (r=0.714, p<0.01). The most promising corn accessions in terms of nutraceutical value came from the CR region.