The effects of a simulated in vitro digestion model on the viscosity of solutions
comprised of high methoxyl, low methoxyl, and low methoxyl amidated pectins were
examined in conjunction with a human satiety study with healthy men (n=10) and women
(n=15). Participants attended 8 morning sessions with a washout period of one week after
a 12 h overnight fast. Self reported measurements were taken for the satiety parameters of
hunger, fullness, satisfaction and prospective food intake using 100 mm VAS scales at
predetermined time intervals over the course of 3 h. Orange juice solutions of each type
of fibre were formulated to be either low viscosity (LV, 0.039±0.007 Pa•s) or high
viscosity (HV, 0.14±0.035 Pa•s). The apparent viscosities of an in vitro digestion model
simulating the gastric and duodenal phases in the presence of hydrolytic enzymes and
bile salts were reported at 10 s-1 and 50 s-1
. All pectin types showed varying apparent
viscosities during the gastric phases, but showed considerable reductions in viscosity
after the final phase. The low-methoxyl low and high viscosity pectin beverages were
associated with the greatest effect on human subjective ratings of satiety, and high
methoxyl low and high viscosity pectin beverages inconsistently exerting effects on
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satiety. Thus, some types of pectin are able to increase perception of satiety in humans.
However, there was not a strong correlation between apparent viscosity of in vitro
digestive fluids and total mean AUC for satiety related questions. Thus, fiber-induced
satiety cannot be explained in full by digestate viscosity alone