Optimal pretreatment determination of kiwifruit drying via online monitoring.

BACKGROUND: Pre-treating is a crucial stage of drying process. The best pretreatment for hot air drying of kiwifruit was investigated using a computer vision system (CVS), for online monitoring of drying attributes including drying time, colour changes and shrinkage, as decision criteria and using clustering method. Slices were dried at 70 °C with hot water blanching (HWB), steam blanching (SB), infrared blanching (IR) and acid ascorbic 1% w/w (AA) as pretreatments each with three durations of 5, 10 and 15 min. RESULTS: The results showed that the cells in HWB-pretreated samples stretched without any cell wall rupture, while the highest damage was observed in AA-pretreated kiwifruit microstructure. Increasing duration of AA and HWB significantly lengthened the drying time while SB showed opposite results. The drying rate had a profound effect on the progression of the shrinkage. The total colour change of pretreated samples was higher than those with no pretreatment except for AA and HWB. The AA could well prevent colour change during the initial stage of drying. Among all pretreatments, SB and IR had the highest colour changes. CONCLUSION: HWB with a duration of 5 min is the optimum pretreatment method for kiwifruit drying. © 2016 Society of Chemical Industry.

Effect of ultrasonic irradiation on the properties and performance of biodiesel produced from date seed oil used in the diesel engine.

In the present study, the effect of ultrasound irradiation on the transesterification parameters, biodiesel properties, and its combustion profiles in the diesel engine was investigated. Moreover, date seed oil (DSO) was firstly utilized in the ultrasound-assisted transesterification reaction. DSO was extracted from Zahidi type date (Phoenix dactylifera) and was esterified to reduce its Free Fatty Acid (FFA) content. Biodiesel yield was optimized in both heating methods, so that the yield of 96.4% (containing 93.5% ester) at 60 °C, with 6 M ratio of methanol/oil, 1 wt% of catalyst (NaOH) and at 90 min of reaction time was reported. The ultrasound irradiation did not influence the reaction conditions except reaction time, reduced to 5 min (96.9% yield and 91.9% ester). The ultrasonic irradiation also influenced on the physicochemical properties of DSO biodiesel and improved its combustion in the diesel engine. The analysis results related to the engine and gas emission confirmed that the ultrasound-assisted produced biodiesel has lower density and viscosity, and higher oxygen content facilitating injection of fuel in the engine chamber and its combustion, respectively. Although, B40 (biodiesel blend consisting of 40% biodiesel and 60% net diesel fuel) as a blend of both fuels presented higher CO2 and lower CO and HC in the emissions, the DSO biodiesel produced by ultrasound irradiation presented better specifications (caused about 2-fold improvement in emissions than that of conventional method). The findings of the study confirmed the positive effect of the ultrasound irradiation on the properties of the produced biodiesel along with its combustion properties in the diesel engine, consequently reducing air pollution problems.