Ultrasound is an emerging technology in various areas of food processing, preservation and safety. Due to its high dehydration efficiency, application of ultrasound prior to frying may hand in promising results in reducing oil uptake. The objective of this study was to examine the effect of ultrasound as well as the simultaneous effect of ultrasound and pre-drying on oil uptake of fried potato strips. Ultrasound pretreatments were performed at 28 and 40 kHz and drying pretreatments were conducted at 80C for 8 and 15 min. Then, frying process was carried out at 150, 170 and 190C. Results showed that, compared to control, oil uptake of samples pretreated with both ultrasound and drying significantly decreased (P < 0.05). It was concluded that at all the frying temperatures, samples pretreated with ultrasound had lower oil uptake in comparison with control samples. PRACTICAL APPLICATIONSDeep-fat frying process is broadly used for both domestic and industrial purposes. High-power (low-frequency) ultrasound modifies food properties by inducing mechanical, physical and chemical or biochemical changes. Ultrasound techniques are relatively cheap, simple and energy saving. It has been demonstrated that decreasing the initial moisture content of raw material reduces oil uptake in the fried product. Regarding high dehydration efficiency of ultrasound, this study provides information on the possibility of using ultrasound-assisted air-drying as a pretreatment prior to frying, in order to investigate oil uptake of fried potato strips.

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The objective of this study was to investigate the effects of concentration (53, 63, and 73°Brix) and temperature (25, 45, and 65°C) on the rheological behavior of grape molasses after 6 months of storage at the ambient condition (25 ± 2°C). According to the results, a pseudoplastic behavior was observed at different temperatures and concentrations for both red and brown phases of the samples. The power law model revealed the best fit to the rheological data and its parameters (K and n) were determined. After storage, the red phase of grape molasses had different K and n values compared to the brown phase. Furthermore, the influences of temperature and concentration on the K were successfully fitted to the studied model. The flow activation energy (Ea) of grape molasses samples was 20.41–58.53 kJ/mol. A quadratic polynomial relationship was also found between the estimated values of Ea and concentrations with high R2. Practical applications This work aimed to study the effect of concentration–temperature combinations on the rheological behavior of different phases of grape molasses after 6 months of storage. The results demonstrated that the storage period affected the rheological behavior grape molasses. In turn, this change affects the quality of the product. Furthermore, rheological behavior of the samples was well predicted by the studied models. These models describing the combined effect of temperature and concentration on the rheological parameters are very valuable for engineering applications.

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