Effect of Different Treatments on the Structural Properties and Flavor of Extruded Corn Flour

Abstract

Extruded corn flour can be easily agglomerated and poses poor flavor. Previous studies have found that phosphorylation heat treatment, enzyme treatment, edible gum dry heat treatment, and composite treatment could significantly reduce the agglomeration rate. The present study sought to explore the effects of sodium orthophosphate heat treatment (S1), neutral protease (S2), xanthan gum dry heat treatment (S3), and sodium orthophosphate-neutral protease treatment (S4) on the structural characteristics and flavor components of extruded corn flour (PCF) using scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, headspace solid phase microextraction, and gas chromatography mass spectrometry. The results showed that the extruded corn flour treated by these four methods exhibited an A-type crystal structure without the formation or introduction of any new chemical bonds or functional groups. The pores and cracks on the surface of starch microparticles significantly increased. Among them, the sodium orthophosphate+neutral protease treated powder had more surface pores and larger cracks than other samples. A total of 130 volatile components were identified by gas chromatography-mass spectrometry, including neutral protease treatment powder (57) > sodium orthophosphate+neutral protease treatment powder (46) > xanthan gum dry heat treatment powder (44) > PCF (41) > sodium orthophosphate heat treatment powder (40). ROAV analysis showed that the key flavor substances of extruded corn flour were mainly ketones. After different treatments, the overall flavor of the powder slightly differed, mainly aldehydes, with grass, orange, and fat flavor. The present study results could provide a theoretical basis to improve the flavor of blended grain powder.

Keywords

• extruded maize flour
• phosphorylation heat treatment
• neutral protease
• scanning electron microscope
• x-ray diffraction
• key flavour substances