Effects of ultrasonicated methylcellulose coating on French fries during deep frying process

Abstract Ultrasonic treatment (UT) effects on methylcellulose (MC) for the food coating purpose prior to deep‐fat frying process of potato strips were demonstrated. Different concentration of MC (0.5–2.0 wt/vol%) solutions were subjected to UT at 20 W to evaluate the effect of UT treated coatings on rheological behavior of the coated samples and their efficiency in minimizing the oil uptake. Application of UT to methylcellulose (UTMC) clearly showed a phase transition from fluid‐ to gel‐like between 20 and 65°C with the increasing in the oscillatory frequency and temperature ramp test of UTMC showed the sol–gel transition occurrence is lower than non‐UTMC at 20 and 29°C, respectively, within the linear viscoelastic region. When the MC concentrations were varied, the most effective concentration was noticed to occur at 1.0 (wt/vol%) UTMC whereby the relative variation of water retention and oil uptake were reduced to about 49.9 and 31.0%, respectively, as compared to 1.0 wt/vol% non‐UTMC formulation. Experimental results affirm that UTMC coating application can be used successively to improve rheological properties of MC by minimizing oil uptake on fried food. Practical Application Ultrasonic treatment (UT) application to methylcellulose (MC) solutions with varied concentration (0.5–2.0 wt/vol%) clearly showed a phase transition from fluid‐to‐gel like with the increasing in the oscillatory frequency (10 −1 to 10 2 rad/s) and temperature ramp test (65–10°C) at low shear strains compared to non‐UTMC. The gelation of UTMC was faster than non‐UTMC when coated onto the substrate at the ambient conditions thus allowed the transformation of green coating layer to form the gel layer instantaneously. Application of MC was successfully in minimizing oil uptake on fried potato strips whereby the most effective layer was noticed to occur at 1.0 wt/vol% UTMC. Introducing UT to polysaccharide coating, that is, MC benefit the food coating industries by increasing the food coating process efficiency so that the coated layer can be fully utilized to increase the function of the coated substrate.