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 oC, 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.

AbstractCarbon nanotubes (CNTs) are a promising candidate material for use in lithium batteries due to 1D tubular structure, high electrical, thermal conductivities, and extremely large surface area. In this work, the MWCNTs were purified by dispersion in a mixture of HNO3 and H2SO4acids. The oxidized-MWCNTs were used as conducting addition to prepare a nanocomposites as high performance cathode material for Li-ion batteries (LIBs). The spinel cathode materials of LiMn2O4 (LMO), doped spinel LiNi0.5Mn1.5O4 (LNMO) were synthesized and characterized via X-rays diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The electrochemical properties of nanocomposites based on LMO/CNTs and LMNO/CNTs were investigated by cyclic voltammetry (CV) as well as electrochemical impedance spectroscopy (EIS). The EIS measurement indicated that the LMO (LNMO)/CNTs nanocomposites showed lower charge transfer resistance (Rct) than that of LMO(LNMO)/ Vulcan carbon materials. In addition, the studied nanocomposites cathodes gave a specific capacity of 145 Ah.kg–1 and 120 Ah.kg–1 for LMO/CNTs (10 wt%) and LNMO/CNTs (10 wt%), respectively, measured at a charge/discharge rate of 0.1C.