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.
A B S T R A C TMembrane processing has found many applications in various industries as an advanced method of separating materials in liquid or gas. The greatest obstacle in using membrane filtration technology is fouling, particularly in porous membranes. The fouling phenomenon is the result of organic and inorganic materials depositing on the surface and pores of membrane. In this study, the effect of ultrasound frequency (37, 80 kHz, and tandem) and amplitude of sonication (30, 60, and 90%) were evaluated on flux recovery during and after microfiltration. Results showed that the 37 kHz and tandem frequencies significantly improved the permeate flux at earlier minutes, particularly when tandem frequency was applied. In addition, the permeate flux was increased as the sonication power increased. However, the interaction effects between frequency and sonication power showed that the ultrasound frequencies were more effective than sonication power on flux recovery. Furthermore, the calculation of fouling percentage showed that both low frequencies and high amplitude together significantly reduced the fouling agents during the cleaning process. However, there were no remarkable statistical effects among the same levels of sonication power during the cleaning process. The interaction effects of various frequencies and powers of ultrasound on cleaning membranes were evaluated and more cleaning efficiency was observed in comparison to sonication power when low frequency applied.
Bene hull contains antioxidant components. Optimum conditions for bioactive compound extraction processes from Bene hull using subcritical water with response surface methodology (RSM) were obtained. Temperature (110-200 o C), processing time (30-60 min), and the water to Bene hull ratio (10:1-50:1) were the investigated factors. The optimal conditions for maximizing the antioxidant activity were 196.8 o C for 52.6 min and a ratio of 43.6:1 for water to Bene hull. Under these conditions, the amount of polyphenolic compounds, the reduction power (RP) (EC 50 ), and the DPPH free radical scavenging activity (RSA) (EC 50 ) were predicted to be 2,284 mg of gallic acid/100 g of Bene hull, 0.2002 mg/mL, and 0.6284 mg/mL, respectively. HPLC analysis was used to identify the main phenolic compounds. The subcritical water extraction technique could be used as a beneficial method to obtain bioactive compounds from Bene hull.
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