Gallic acid-modified starch conjugates inhibit harmful aldehydes in fried battered fish: Based on structural...

A gallic acid (GA)-grafted modified starch conjugate was prepared and characterized to evaluate its inhibitory effect on harmful aldehydes in fried battered fish. GA was successfully covalently grafted onto modified wheat flour (WSU) and corn starch (CSU), as confirmed by ¹H NMR. The grafting efficiency peaked at a 1.6% GA concentration, reaching 76.4% for WSU and 46.2% for CSU. Compared to the control, the grafted conjugates exhibited increased short-range order and crystallinity, and reduced enthalpy change (ΔH). SEM analysis revealed smoother surface morphology in conjugates formed with lower GA concentrations, while higher GA concentrations appeared lamellar structures on starch granule surfaces. After GA grafting, the WSU-GA and CSU-GA conjugates exhibited enhanced radical scavenging activity. The highest DPPH, ABTS, and hydroxyl radical scavenging rates reached 80.62%, 49.59%, and 27.5% for WSU-GA, and 79.07%, 63.98%, and 43.1% for CSU-GA, respectively. When incorporated into batter, the conjugates increased relaxation times but decreased water retention, storage modulus (G'), loss modulus (G"), and pick-up. No significant changes were observed in free and total sulfhydryl group content. In fried battered fish, coatings containing WSU-GA and CSU-GA led to increased moisture loss, oil penetration, yet effectively inhibited the formation of harmful aldehydes. Specifically, WSU-GA1.6/CSU-GA1.6 reduced malondialdehyde, 4-hydroxy-2-hexenal, and 4-hydroxy-2-nonenal contents by 62.1%, 76.1%, and 66.2%, respectively, which was attributed to the strong antioxidant capacity of the conjugates. This study demonstrates a promising strategy for employing starch-polyphenol conjugates to mitigate the formation of hazardous compounds in fried foods.