Interactions between pectin, starch and linoleic acid and their effects on starch structure, digestion and release properties

This study aimed at gaining insight into the mechanism of interactions between pectin (PE), starch and unsaturated fatty acids (UFAs) in relation to structure, in vitro digestibility and release properties of starch. Due to the barrier and encapsulation effects of PE, the complexing behavior of potato starch (PtS) with linoleic acid (LOA) was enhanced, which increased the complexing index, the compactness of network structure, short-range ordered structure and relative crystallinity of PtS-LOA-PE films. These structural changes resulted in the increases of slowly digestible starch and resistant starch and in the decreases of first-order rate coefficient in PtS-LOA-PE films. Besides, the in vitro release results also showed that the release properties of PtS-LOA could be controlled by the PE addition with the decreases in LOA release rate and increase in LOA bioavailability under simulated gastrointestinal conditions. Notably, at different PtS-LOA:PE ratios, the PtS-LOA-PE film with the PtS-LOA:PE ratio of 5:1 showed the better complexing degree, structural order, anti-digestibility and colon-targeted release properties than other PtS-LOA-PE films. These results indicated that PE influenced the release properties of the PtS-LOA-PE films, which was closely related to their complexing degree, structural order, and digestibility. This study provided new insights into the design of resistant films for delivery of UFAs to colon. Schematic representation of PE, PtS and LOA interactions and their regulation of starch structure. [Display omitted] •PE enhanced the hydrophobic interaction between PtS and LOA through hydrogen bonds.•PE successfully encapsulated the PtS-LOA complexes with higher complexing degree.•PtS-LOA-PE films had better anti-digestibility with higher RS and SDS contents.•PtS-LOA-PE films showed controlled release behavior of LOA to colon.