Effect of ultrasonication on physicochemical and foaming properties of squid ovary powder

Central composite design (CCD) in conjunction with response surface methodology (RSM) was used to optimize the ultrasonication conditions for the improvement of foaming properties of squid ovary powder (SOP). Ultrasonication at amplitude 70% for time 30 min was the optimized condition based on predictive models. Ultrasonication affected physicochemical properties and structure of SOP. Surface hydrophobicity of ultrasonicated SOP was increased by 28%. Solubility was decreased slightly with coincidental decrease in total sulfhydryl group. Nevertheless, ultrasonication had no impact on protein pattern. Mean particle size was reduced by 64.1% for SOP after ultrasonication. Differential scanning calorimetric study revealed that ultrasonication affected transition temperature of proteins in SOP. Foaming capacity (FC) of ultrasonicated SOP was increased by 83.3%, compared to the control. When effect of various whipping times on foam properties was examined, the maximum FC (320%) and the lowest liquid drainage was attained when the ultrasonicated SOP was whipped for 3 min. Ultrasonication also improved the foam properties of SOP by increasing G' and G'. Microstructure study revealed that smaller sized bubbles with uniform distribution and thicker lamella were obtained in foam of ultrasonicated SOP. Additionally, foam of ultrasonicated SOP was more stable after 60 min. Thus, ultrasonication under the optimal condition along with appropriate whipping time yielded the foam from SOP with increased foaming capacity and stability. (C) 2017 Elsevier Ltd. All rights reserved.