In the present study, the Iranian jujube honey was evaluated for its total antioxidant activity by DPPH assay, total phenolic content (TPC) by using the Folin–Ciocalteu reagent, and brown pigment formation (BPF). The kinetics of changes in jujube honey samples heated at various temperatures (45, 55 and 65 °C) over 10 days were studied. Increasing treatment temperature and time caused an increase in all three parameters including, antioxidant activity, BPF and TPC. Increases in BPF and TPC followed zero-order kinetics, and the rise in antioxidant activity varied depending on heating temperatures, following second-order, first-order and zero-order kinetics when samples were heated at 45, 55 and 65 °C, respectively. At 45–65 °C, activation energy values of 68 and 64.7 kJ/mol−1 were obtained for BPF and TPC, respectively. Linear relationships were observed between antioxidant activity and BPF, TPC and antioxidant activity, and BPF and TPC, such that the highest phenol content was related to the darkest honey sample. For all three parameters, heating honey to 65 °C was found to be more effective than heating to 45 or 55 °C.

Cobalt cerium oxides, prepared using a co-precipitation procedure, were studied as catalysts for the conversion of synthesis gas to light olefins (C 2 -C 4 ). Specifically, we studied the effect of a range of preparation variables, including the molar ratio of the [Co]/[Ce] of the precipitation solution, ageing time and calcination temperature. In addition, the effects of supports and promoters on the catalysts' activity and selectivity and a range of reaction temperatures using synthesis gas with different H 2 /CO molar feed ratios were investigated. The catalyst containing a molar ratio of 80% Co and 20% Ce, aged for 2 h, supported with 15 wt% SiO 2 without any promoter, at an operating temperature of 450 ºC and an H 2 /CO feed ratio of 2/1 (GHSV = 4500 h -1 ), performed optimally for the conversion of synthesis gas to light olefins. The characterization of both the precursors and the calcined catalysts by powder X-ray diffraction, scanning electron microscopy, Brunauer-Emmett-Teller specific surface area measurements and thermal analysis methods, including TGA and DSC, show that all the preparation variables influenced the catalyst precursor structure.

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Summary Interaction between biopolymers generates different rheological behaviors, which can be effective on the structure of food products. One way to control the polysaccharide–protein interaction is the variation of acidic and ionic strength. In this research, the different amounts of pHs (3–7) and calcium chloride (5–20 mM) were investigated on a soluble complex of whey protein concentrate (WPC) with xanthan gum (XG) and basil seed gum (BSG). The complex characteristic was investigated according to turbidity, viscosity behavior, and electrostatic interactions. The turbidity test showed that WPC:BSG and WPC:XG absorbance increased at pH 3.5 and 4.5, respectively, due to the formation of insoluble complex. pH 6 was the start point of the turbidity increment, which showed the formation of soluble complexes between WPC and polysaccharides. The FTIR analysis confirmed creation of soluble complex at pH 6. The absorbance raised with increasing the molar of CaCl2 to 10 mM, but no significant difference was observed by turbidity test in the range of CaCl2<10 mM. Also, the highest viscosity value was obtained by 10 mM CaCl2.