Modulating the in vitro gastrointestinal digestibility of crystalline oil-in-water emulsion: Different fat crystal sizes and polymorphic forms under the same SFC.

The effects of the fat crystal structure on lipid droplets digestion behaviors were investigated using an in vitro digestion model. The crystalline oil-in-water emulsions containing the same solid fat content (SFC) with different fat crystal sizes and polymorphic forms were fabricated by different storage protocols: constant-temperature and inconstant-temperature storage. Oral and gastric processing led to a significant increase (p < 0.05) in the d4,3 values of the two emulsions, and the two emulsions underwent partial coalescence and flocculation/aggregation. The free fatty acid (FFA) release profiles showed that the lipolysis extent decreased due to a larger crystal size. In addition, the two emulsions showed differences in beta polymorphism. This work further demonstrated that the FFA release could be modulated by the physical properties of the fat.

In Vitro Gastrointestinal Digestibility of Crystalline Oil-in-Water Emulsions: Influence of Fat Crystal Structure.

To investigate how the fat crystal structure affects lipid in vitro digestibility, 30% palm stearin-in-water emulsions were prepared after storage at different temperatures (4, 25, and 37 °C) for 1 h, which consisted of different polymorphic forms, sizes, and quantities of fat crystals. The variation of particle size ( d4,3), zeta potential, and microstructure during the gastrointestinal digestion and the free fatty acid (FFA) released in small intestine phase were investigated. After oral and gastric digestion, all of the emulsions underwent partial or complete coalescence and flocculation. During intestinal digestion, the d4,3 and zeta potentials did not notably affect lipid digestion. The FFA-released assay results indicated that the lipid digestion extent decreased as the fat crystal size and content of the ß polymorph increased, and there was no obvious relationship between FFA release and fat crystal quantity or solid fat content (SFC). This study highlighted the crucial roles of fat crystal size and polymorphic form in regulating the digestion behavior of lipid-based O/W emulsions.

Differences of starch granule distribution in grains from different spikelet positions in winter wheat.

Wheat starch development is a complex process and is markedly difference by changes in spikelet spatial position. The present study deals with endosperm starch granule distribution and spatial position during filling development. The study was conducted with pure starch isolated from wheat (Triticum aestivum L.), Jimai20 and Shannong1391, at 7-35 days after anthesis (DAA). The results showed that grain number, spikelet weight and grain weight per spikelet in different spatial position showed parabolic changes. Upper spikelets had highest starch and amylose content followed by basal spikelets, then middle spikelets. The paper also suggested the volume percents of B-type and A-type granule in grain of middle spikelets were remarkably higher and lower than those of basal and upper spikelets, respectively. However, no significant difference occurred in the number percents of the two type granule. The ratio of amylase to amylopectin was positively correlated with the volume proportion of 22.8-42.8 µm, but was negatively related to the volume proportion of <9.9 µm. The results indicated that the formation and distribution of starch granules were affected significantly by spikelet position, and grains at upper and basal spikelet had the potential of increasing grain weight through increasing the volume of B-type granules.