Andean blackberries (Rubus glaucus Benth) are fruits rich in phytocomponents with high antioxidant activity. In this work, the changes in the total polyphenol content (TPC), the total flavonoid content (TFC), and the total anthocyanin content (TAC) of four blackberry varieties at three maturity stages (E1-25%, E2-50%, and E3-100%) were measured. The antioxidant activity (AA) was evaluated using the 2,2’azinobis-(3-ethylbenzthiazolin 6-sulphonic acid (ABTS) and ferric reducing antioxidant power (FRAP) methods. TPC and TFC content decreased with the increase in the maturity stage. The blackberry Brazos cultivar presented TPC values of 51.26, 38.16, and 31.59 mg of gallic acid equivalents (GAE)/g dry weight (DW) at E1, E2, and E3, respectively. The TAC and soluble solids increased with the increase in the maturity stage of the fruits. The Andimora variety at E3 presented a high TPC content, and the Colombiana variety presented a high TFC content. The blackberry Colombiana cultivar presented TAC values of 1.40, 2.95, and 12.26 mg cy-3-glu/100g DW at E1, E2, and E3, respectively. The blackberry Colombiana cultivar presented a high AA value at 1278.63 µmol TE/g DW according to the ABTS method and 1284.55 µmol TE/g DW according to the FRAP method. The TPC and TFC showed a high correlation with the AA according to the ABTS and the FRAP methods. The Pearson correlation between the TFC and AA/ABTS has a value of r = 0.92. The TFC and AA/FRAP present a value of r = 0.94.

Anthocyanins, carotenoids and polyphenols are biomolecules that give the characteristic color to fruits. Carotenoids relate to yellow, orange and red colors whereas anthocyanins and polyphenols mainly relate to purple and red colors. Presently, standard determination of antioxidants is carried out using relatively complex methods and techniques. The aim of this study was to develop a mathematical prediction model to relate the internal color parameters of the Amazonic fruits araza (Eugenia stipitata Mc Vaugh), Andean fruit blackberry (Rubus glaucus Benth), Andean blueberry (Vaccinium floribundum Kunth), goldenberry (Physalis peruviana L.), naranjilla (Solanum quitoense Lam.), and tamarillo (Solanum betaceum Cav.) to their respective anthocyanins, carotenoids and polyphenols contents. The mathematical model was effective in predicting the total anthocyanins content (TAC), the total carotenoids content (TCC) and finally the total phenolic content (TPC) of fruits assayed. Andean blueberry presented a TPC with an experimental value of 7254.62 (mg GAE/100 g sample) with respect to a TPC prediction value of 7315.73 (mg GAE/100 g sample). Andean blackberry presented a TAC with an experimental value of 1416.69 (mg chloride cyanidin 3-glucoside/100 g) with respect to a prediction TAC value of 1413 (mg chloride cyanidin 3-glucoside/100 g).

Objective: To obtain biofilms from starch and cellulose present in the avocado (Persea americana) peel and seed. Materials and methods: The starch characterization included humidity, gelatinization temperature, paste clarity, absorption index, solubility index, swelling power, amylose, amylopectin, amount, and starch yield. Five mixtures were made with 3 g of starch, 5 mL of 30 % NaOH (w/v), 3 g of cellulose, and different proportions for glycerin: 2 g; 2.5 g; 3 g; 3.5 g; 4 g, and PVA: 2 g, 3 g, 4 g, 5 g, and 6 g. Films were formed on acrylic plates, using the casting method. The bioplastic was characterized in terms of moisture, solubility in water, density, thickness, biodegradability, stress, deformation, and modulus of elasticity. Results and discusión: The addition of cellulose to the mixture does not contribute to film formation, unlike PVA which did. The film had the best physical appearance with a mixture of 2 g of glycerin and 6 g of PVA. The bioplastic characterization was 23.43 % humidity, 39.39 % for water solubility, 1.52 g/cm3 density, 0.58 mm thickness, 21.03 % weight loss for the biodegradability test, 1.53 MPa for tension, 21.25 % deformation, and 10,04 MPa for the modulus of elasticity. Conclusions: The bioplastic obtained did not show the resistance of traditional plastic. However, the results obtained serve as a starting point for the realization of other formulations, aimed at producing a bioplastic capable of competing with its synthetic relatives.

La modificación química de los almidones es un procedimiento ampliamente utilizado. En este estudio se realizó la esterificación del almidón extraído de las semillas de aguacate (Persea americana), se caracterizó y se utilizó para obtener un bioplástico por el método de fundición. Para ello se utilizaron tres plastificantes: alcohol polivinílico, glicerol y sorbitol; además de agua y una solución de NaOH al 15% (m/v). Se realizaron 27 formulaciones preliminares para verificar la formación de bioplástico y a partir de allí, se tomó como unidad experimental 5 g de almidón, 4 mL de agua destilada, 4 mL de solución de NaOH y 2 g de plastificante. Al caracterizar el bioplástico, se determinó que los mejores resultados en cuanto a humedad y permeabilidad al vapor de agua se obtuvieron en el material donde se utilizó sorbitol, con 5% y 397,80 g/cm².día respectivamente. Por su parte el bioplástico que se plastificó con glicerol, exhibió mejores propiedades mecánicas con relación al resto evaluado, con una tensión de 0,33 MPa, deformación del 25,40% y biodegradabilidad del 54,34% respecto al peso perdido.