Lipid-mediated formation of amylose-lipid complexes in cold-stored mashed potatoes: Structural evidence and in vitro starch digestibility

After gelatinization, amylose chains in starchy foods face two competing ordering pathways during cold storage: retrogradation-driven reassociation (RS3-type) and lipid-mediated inclusion complexation (RS5-type). This study examined whether mayonnaise-derived lipids modulate starch reassembly in mashed potatoes during storage. Mashed potatoes with or without mayonnaise (105 g potato: 24 g mayonnaise) were stored at 0 °C and 10 °C for up to 72 h. Starch structural evolution was characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, and differential scanning calorimetry, while digestion behavior was evaluated using the INFOGEST 2.0 in vitro model. Storage alone promoted retrogradation-associated ordering in the control samples, particularly at 0 °C. Mayonnaise incorporation promoted the formation of B + V-type crystalline structures and thermally stable amylose-lipid complexes, indicating that lipid-mediated complexation supplemented the dominant retrogradation process with an additional RS5-type ordering pathway. Consistently, mayonnaise-containing samples exhibited lower rapidly digestible starch and higher resistant starch after storage, with the strongest effect observed in LCCT-M (over 59% RS). Overall, mayonnaise acted as a food-grade emulsion that diverted part of starch reorganization during cold storage from the dominant RS3-type retrogradation route toward RS5-type amylose-lipid complexation, offering a simple, mechanism-based strategy for designing slow-digesting starchy foods under cold-chain conditions.