Impact of storage conditions and variety on quality attributes and aroma volatiles of pitahaya (Hylocereus spp.)

Abstract

Pitahaya are increasing in popularity but knowledge on the effects of storage and the potential impact of variety on subsequent quality following storage is incomplete, particularly in terms of the potential effects on sensory acceptability. In this study six varieties of pitahaya, having white, pink, and red internal flesh coloration, were harvested and evaluated for sensory and quality attributes at harvest and following storage for two weeks at either 5°C or 10°C. Storage did not influence overall visual liking or color of the external portion of the fruit as discerned by the panelists. Alterations in the internal flesh color, such as a slight darkening, were noted to occur by instrumental measurement, but these differences were not noticeable to the panelists. Losses in sugars and acids occurred in the flesh during storage at both storage temperatures and were related to declines in fructose, glucose and malic acid. In contrast, antioxidant activity was reduced by storage at 5°C but was unchanged at 10°C, with betacyanin concentration not differing from that determined at harvest. Aldehydes were the most abundant aroma volatiles detected in juice from the flesh, with storage increasing total aldehyde amount, particularly at 10°C. Total alcohols, on the other hand, were reduced by storage, the amount of reduction not dependent on storage temperature. Regardless of the storage-induced changes in the various components measured, panelists did not report any significant differences in overall liking, flavor, sweetness, tartness or texture. There were substantial varietal differences in sensory and quality attributes, regardless of the impact of storage. ‘Cebra’ had very low sweetness relative to the other varieties and had low flavor and overall liking scores. Panelist perception of flavor quality was most closely linked with varietal differences in SSC and TA, although there were clear differences in aroma volatiles as well. Mexicana, a white-fleshed variety, had the lowest antioxidant activity, corresponding to low amounts of the red betacyanin pigments. The study indicated that storage, and particularly that at 10°C, caused a variety of measureable changes in a range of pitahaya quality parameters but that these changes did not substantially alter the sensory quality of the fruit. Further research is needed to determine whether or not varietal or storage-induced differences in aroma volatile content have an impact on pitahaya flavor.