Frying of Potato Strips Pretreated by Ultrasound-Assisted Air-Drying

Abstract

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.

Determination of bulk density of Mirabelle plum during hot air drying as influenced by ultrasound-osmotic pretreatment

“…Rodriguez et al [26], through microstructural analysis, observed that ultrasound application disrupted the cellular structure and resulted in pores which were larger than those in fresh samples. This fact could improve the drying rate by making an easier water pathway, which, in turn, could lead to a higher moisture diffusivity, and a consequently to a higher moisture loss [27,28] and a higher bulk density in which the space left free by moisture loss is occupied by an osmotic medium such as sucrose. Garcia-Noguera et al [15] in experiments with strawberries, showed that increasing the time of ultrasound pretreatment reduced moisture content of the samples.…”

Application of pretreatment methods on agricultural products prior to frying: a review

“…The novel pretreatment methods are the recent emerging technologies being used in the food industry because of their advantages (eco‐friendly, fast, nutrient preservation, low energy usage, cost effectiveness and so on) over the conventional methods . These include superheated steam drying, infrared technology, ultrasound, microwave technology and pulsed electric field . The classification of various pretreatment methods is summarised in Fig.…”

“…The results observed in UAOD pretreated samples were as a result of cavitation effect on the structure of potato caused by the application of ultrasound. In a related experiment, Dehghannya et al . determined the effects of ultrasound‐assisted air drying pretreatment of potato strips on the oil content of fried potato strips.…”

“…The results observed in UAOD pretreated samples were as a result of cavitation effect on the structure of potato caused by the application of ultrasound. In a related experiment, Dehghannya et al 25 determined the effects of ultrasound-assisted air drying pretreatment of potato strips on the oil content of fried potato strips. The pretreatments were done using ultrasound water bath of frequencies of 28 and 40 kHz and in combination with drying pretreatments at 80 ∘ C for 8 and 15 min prior to frying at 150, 170 and 190 ∘ C. They observed that the ultrasound pretreated samples had a lower oil content compared with control samples (without ultrasound pretreatments).…”

Effects of ultrasound pretreatments on the quality of fried sweet potato (Ipomea batatas) chips during microwave‐assisted vacuum frying

“…The path required for diffusion increases as the moisture content decreases and the resistant to outward diffusion of moisture greatly increased with the increase of solid and/or oil content (Bravo, Sanjuán, Ruales, & Mulet, 2009). The crust formed during frying also prevented the absorption of oil during cooling process (Dehghannya, Naghavi, & Ghanbarzadeh, 2016). Lower initial moisture content resulted lower oil uptake.…”