Tailoring the physicochemical properties of starch: impact of integrated ultrasonic and ethanol pretreatment on the oil uptake of infrared fried ginkgo seeds

Abstract

BackgroundThe structural changes of starch would have a more crucial impact on oil absorption and quality changes in starch‐rich fruits and vegetables during frying process with enhanced heat transfer (such as infrared frying). Currently, the influence of integrated ultrasonic and ethanol (US+ethanol) pretreatment on the oil uptake in infrared fried (IF) ginkgo seeds was evaluated regarding the modifications in physicochemical properties of starch. The pretreatment was performed with the ultrasonic (40 kHz, 300 W) and ethanol osmotic (95%, v/v) treatment individually or integrated for 40 min.ResultsThe mass transfer in the pretreatment was facilitated by combined ultrasound and ethanol. The swelling power, solubility, and gelatinization degree of starch was significantly increased. LF‐NMR curves and images revealed that the bound water fraction in ginkgo seeds was increased and the water distribution was homogenized. The Fourier transform‐infrared spectrum and differential scanning calorimeter results presented that the crystalline regions of starch were reduced and the thermal enthalpy was decreased after the US+ethanol pretreatment. The total, surface, and structural oil content in IF ginkgo seeds with US+ethanol pretreatment were reduced by 29.10%, 34.52%, and 29.73%, respectively. The US+ethanol pretreatment led to a thinner crust layer with increased porosity and smaller‐sized pores in the IF ginkgo seeds as observed by stereo microscope and scanning electron microscopy.ConclusionThe changes in structural and physicochemical properties of starch by combined ultrasound and ethanol would affect the crust ratio and pore characteristics in fried high‐starch fruits and vegetables, thereby reducing the oil absorption.This article is protected by copyright. All rights reserved.