Evidence for amylose inclusion complexes with multiple acyl chain lipids using solid-state NMR and theoretical approaches

Oleic acid treatment of rice grains reduces the starch digestibility: Formation, binding state and fine structure of starch-lipid complexes

Rice contains abundant starch and contributes to a rapid rise in postprandial blood glucose levels. Hence, it is crucial to directly modify rice grains for resistant starch (RS) content elevation while preserving their morphology. In this study, rice grains were treated with 6%-18% concentrations of oleic acid (OA) and 8-20 h of soaking time to promote the formation of starch-lipid complexes, thereby reducing rice digestibility. In OA-treated rice, the OA molecules exist in three binding states. OA-treated rice exhibited a significantly higher complexation index and OA content than natural rice. RS content increased from 20.50% to 32.46%. X-ray diffraction and NMR spectroscopy revealed the development of amylose-OA complexes within the rice grains and a V-crystalline structure of up to 3.62%. Raman spectroscopy and thermogravimetric analysis showed enhanced molecular ordering and structural stability of rice starch. Overall, OA treatment effectively promotes RS formation within rice grains, consequently reducing rice digestibility.

The structural properties and resistant digestibility of maize starch-glyceride monostearate complexes

This study investigated the effects of pullulanase debranching on the structural properties and digestibility of maize starch (MS)-glyceryl monostearate (GMS) complexes. According to our results, the apparent amylose content of MS increased from 36.34 % to 95.55 % and complex index reached 93.09 % after 16 h of pullulanase debranching. The crystallinity of prepared MS-GMS complexes increased to 33.24 % with a blend of B-type and V-type crystals. The surface of prepared MS-GMS complexes granules emerged more small lamellar crystals tightly adhering to the surface of granules. The Fourier transforms infrared spectroscopy analysis showed that debranching pretreatment MS-GMS complexes exhibited higher levels of short-range orders structure. These results indicated that maize starch was favorable to form more ordered starch-lipid complexes structure after debranching pretreatment, which resulted in the restriction of starch hydrolysis. In vitro digestion data implied that resistant starch (RS) content increased with the extension of the debranching time, and the highest RS content (69.58 %) appeared with 16 h pullulanase debranching. This work suggests that debranching pretreatment could be an efficient way to produce ordered starch-lipid complexes with controllable structure and anti-digestibility.

Development, application and future trends of starch-based delivery systems for nutraceuticals: A review

As a natural biopolymer, starch is ideally adapted as an encapsulant material for nutraceutical delivery systems due to its unique nature of extensive sources, versatility and high biocompatibility. This review offers an outline of recent advances in the development of starch-based delivery systems. The structure and functional properties of starch in encapsulating and delivering bioactive ingredients are first introduced. Structural modification of starch improves the functionalities and extends the applications of starch in novel delivery systems. Then, various nutraceutical delivery systems are systematically summarized, which include porous starch, starch particle, amylose inclusion complex, cyclodextrin, gel, edible film and emulsion. Next, the delivery process of nutraceuticals is discussed in two parts: digestion and release. Intestinal digestion plays an important role during the whole digestion process of starch-based delivery systems. Moreover, controlled release of bioactives can be achieved by porous starch, starch-bioactive complexation and core-shell structure. Finally, the challenges of the existing starch-based delivery systems are deliberated, and the directions for future research are pointed out. Composite delivery carriers, co-delivery, intelligent delivery, delivery in real food systems, and reuse of agricultural wastes may be the research trends for starch-based delivery systems in the future.