Joel Corrales-García

Effect of gibberellic acid and (2-chloroethane) phosphonic acid on glochid abscission in cactus pear fruit (Opuntia amyclaea Tenore)

Abstract Glochids (small spines) of cactus pear negatively affect harvest operations, and the quality and acceptance of this fruit. Different treatments for pre-harvest removal of glochids were evaluated. Gibberellic acid (GA3, 100 ppm) was sprayed over flower buds in six consecutive applications (every 7 days) during their development. Also, solutions of (2-chloroethane) phosphonic acid or ethephon (‘Ethrel’®) at 500, 600, 700, 800, and 900 ppm a.i. were sprayed over the buds immediately after fruit set, alone or in combination with GA3 applications. At harvest, it was concluded that GA3+ethephon treatments generally increased the length as well as the number of glochids compared with glochids on control fruit. Ethephon applications only caused slight abscission of glochids prior to harvest. However, after the mechanical effect of harvest, GA3+ethephon treatments caused significant abscission of glochids (>90% in the best case) compared with the controls (37%), while ethephon (alone) treatments caused 79% of glochids to abscise in the best case (700 ppm). None of the treatments negatively affected the quality of the fruit in terms of soluble solids concentration, acidity, color, weight of pulp and weight of peel.

Nutraceutical components, antioxidant activity and color of eleven varieties of prickly pear ( Opuntia sp.)

In Mexico, there are 50 recorded varieties of the prickly pear fruit. National production covers only the white-pulp fruit, but other red varieties have export potential; however, their nutraceutical properties are unknown. The pulp and peel (underutilized tissue) of the pigmented fruits of the genus Opuntia sp. are marketed on a limited basis. They represent an alternative source of stable pigments (betalains), which are associated with antioxidant properties, for the agroindustry. The objective was to assess the content of nutraceutical components, antioxidant activity, and peel and pulp color of 11 varieties of the prickly pear fruit that are marketed on a small scale. Statistical analysis revealed that Roja Villanueva peel had the highest betalain content (39.97 mg 100 g-1 FW). Altena Blanca peel demonstrated the highest concentration of phenolic compounds (618.39 mg GAE 100 g-1 FW), whereas Altena Roja had the highest ascorbic acid content (37.14 mg AAE 100 g-1 FW). The greatest nutraceutical potential was observed in the pulp of the non-marketed Tzaponopal Rojo variety of the species O. robusta var. larreyi, due to the high antioxidant activity (0.0183 mg mL-1), as well as the darkest color (‹ hue value, 12.31) and the lowest lightness (‹ luminosity, 19.31), which coincides with the highest betalain concentration.