Protection of antioxidants in pitaya (Hylocereus undatus) peel: effects of blanching conditions on polyphenoloxidase, peroxidase and antioxidant activities

Abstract

Pitaya peel is a by-product of the fruit processing, rich in phytochemicals and has great potential for application in food industry. In this study, blanching was applied to the pitaya peel treatment for inactivation of the polyphenoloxidase (PPO) and peroxidase (POD) which caused the antioxidant loss in the material during the processing and preservation. The effects of blanching temperature and time on the PPO and POD activities as well as the stability of betacyanins and phenolics of pitaya peel were investigated. At the blanching temperature of 98 ± 2 o C, the inactivation rate constants and half-life values of PPO and POD were 6.6 × 10 -3 .s -1 and 105 s and 16.6 × 10 -3 .s -1 and 42 s, respectively. During the blanching, betacyanins and phenolics were partially destroyed, their degradation rate constants and half-life values were 9.3 × 10 -4 .s -1 and 744 s and 3 × 10 -4 .s -1 and 2310 s, respectively. During the storage of dried pitaya peel powder (PPP), the degradation rate constants of betacyanins and phenolics of the blanched PPP were 1.4 and 1.8 times, respectively lower than those of the unblanched PPP. In addition, reduction in DPPH radical scavenging and ferric reducing antioxidant power of the blanched PPP was significantly lower than that of the unblanched PPP.

Impact of Pretreatment and Drying Factors on Chemical and Biochemical Attributes of Moroccan Thompson Seedless Grapes

“…But the grapes lose their texture at this duration. Similar findings were reported by Noreña and Rigon [48] and Mai et al [49] regarding the effect of blanching duration on PPO and POD inhibition. During blanching, the heat denatures the PPO and POD protein structures and deactivates the enzymes by disrupting the weak bonds that hold the enzyme molecules together, resulting in the loss of their catalytic activity [50].…”

Supplementation of pitaya peel powder to cookie formulation: Effects of ratio of pitaya peel powder on the product quality, predicted glycemic index and antioxidant release during in vitro sequential digestion

“…Total carbohydrate content was calculated by subtracting the sum of protein, fat, and ash percentages from 100%. Betacyanin and total phenolic contents as well as DPPH inhibition activity and ferric reducing power were evaluated according to the procedure described by [21].…”