Structure-property relationships in starch-alkyl gallate inclusion complexes: Implications for oil absorption, digestion, and antioxidant capacity during frying

Inclusion complexes retained stable V-type crystals after frying. • CS-PG and CS-HG reduced oil uptake and improved antioxidant capacity. • Complexes increased resistant starch and inhibited starch hydrolysis. Deep-frying, while widely used for its desirable sensory attributes, poses health concerns due to high oil absorption and lipid oxidation. In this study, we synthesized a series of corn starch-alkyl gallate inclusion complexes with varying acyl chain lengths (C1-C18) and systematically investigated their structure-property relationships during frying, focusing on structural stability, oil absorption, antioxidant capacity, and starch digestibility. XRD, FTIR, and SEM analyses confirmed that all complexes retained a stable V type crystalline structure after frying, with CS-PG (C3) and CS-HG (C16) exhibiting the lowest oil absorption due to their superior crystalline order and compact lamellar organization. However, antioxidant evaluation revealed a distinct chain length dependency: CS-OG (C8) demonstrated the most effective suppression of lipid oxidation, as evidenced by the lowest peroxide value (POV) and thiobarbituric acid reactive substances (TBARS) levels. This divergence highlights a critical performance trade off, wherein intermediate chain lengths optimize antioxidant activity at the oil-starch interface, while shorter and longer chains favor structural integrity and oil barrier properties. Digestibility assays further showed that complexation effectively reduced rapidly digestible starch (RDS) and increased resistant starch (RS) content, with the extent of enzymatic resistance generally improving with chain length. Collectively, these findings demonstrate that the functional performance of starch-alkyl gallate inclusion complexes is governed by alkyl chain length in a property dependent manner. Rather than a single “best” formulation, the optimal chain length varies according to the target application, CS-PG and CS-HG for low oil fried foods, and CS-OG for enhanced oxidative stability. Download: Download high-res image (243KB) Download: Download full-size image