SENSORIAL, PHYSICAL AND CHEMICAL CHANGES OF PITAHAYA FRUITS (Hylocereus undatus) DURING DEVELOPENT

Abstract

In this work we evaluated some physical and chemical changes occurring during fruit development and ripening of pitahaya (Hylocereus undatus), in order to define the maturity stage for harvesting at the best organoleptic quality and acceptance by consumers. Fruit development was monitored in field conditions, at 26.1 °C and 73.9 mm of mean temperature and rain during the evaluation period. Starting at flower opening, changes in fruit diameter (polar and equatorial), fresh weight of whole fruit as well as pulp and skin were evaluated; when the first reddish coloration appeared on the skin, skin color was measured, as wellas pulp firmness, total soluble solids content (°Brix), reducing sugar content, titratable acidity, ascorbic acid content and sensorial perception. Ripening occurred between 25 and 31 d after flower opening, when the skin changed color from green to incipient red to red-purple, along with a reduction in pulp firmness. The contents of reducing sugars and soluble solids increased from 2.4 to 6.6 % and from 4.6 to 12.6 %, respectively; malic acid content diminished from 1.4 to 0.4 %, thus favoring the increase in the °Brix/acidity ratio. The ascorbic acid content diminished from 14.7 to 9.6 mg/100 g. At 31 d fruits were 8.9 cm in polar diameter, 8.2 cm in equatorial diameter and weighted 469.2 g. The flavor changed from bittersweet to sweet between 27 and 31 d, so the major acceptance was registered between 29 and 31 d.