Quality attributes of stored koubo (Cereus peruvianus (L.) Miller) fruit

Cereus peruvianus (L.) Miller (koubo, also known as apple cactus) is a new fruit crop in Israel. When the fruit reach full maturity, they tend to crack due to uncoordinated growth of the different fruit tissues. This phenomenon normally causes heavy fruit losses, as much as 90% of the total yield. To prevent this problem, fruit are usually harvested before they reach full ripening, i.e. at the violet stage, a practice that effectively prevents cracking, but also reduces the overall quality of the marketed fruit. In order to establish optimal harvesting protocols and storage conditions, we characterized fruit ripening under storage, comparing purple-harvested fruit, stored fruit (purple and red-ripe) and tree-ripened red-split fruit. Organoleptic tests indicated that the overall flavor increased concomitantly with the development of the red peel color. During ripening, the pH slightly increased, while titratable acidity and the content of malic acid decreased. These changes were more marked in stored than in tree-ripened fruit. The levels of polysaccharides, glucose and fructose did not change significantly during storage. The content of linalool and linalool derivatives increased dramatically during storage, being much higher than that of cracked tree-ripened fruit. Our results indicated that the overall quality of the fruit increased during storage as expressed by color change, decreased acidity and enhanced levels of aroma compounds, while the content of carbohydrates was practically unaffected.