Pasta Structure Affects Mastication, Bolus Properties, and Postprandial Glucose and Insulin Metabolism in Healthy Adults

Abstract

Background Structure and protein–starch interactions in pasta products can be responsible for lower postprandial glycemic responses compared with other cereal foods. Objectives We tested the effect on postprandial glucose metabolism induced by 2 pasta products, couscous, and bread, through their structural changes during mastication and simulated gastric digestion. Methods Two randomized controlled trials (n = 30/trial) in healthy, normal-weight adults (mean BMI of 23.9 kg/m2 (study 1) and 23.0 kg/m2 (study 2)) evaluated postprandial glucose metabolism modulation to portions of durum wheat semolina spaghetti, penne, couscous, and bread each containing 50 g available carbohydrate. A mastication trial involving 26 normal-weight adults was conducted to investigate mastication processes and changes in particle size distribution and microstructure (light microscopy) of boluses after mastication and in vitro gastric digestion. Results Both pasta products resulted in lower areas under the 2-h curve for blood glucose (−40% for spaghetti and −22% for penne compared with couscous; −41% for spaghetti and −30% for penne compared with bread), compared with the other grain products (P < 0.05). Pasta products required more chews (spaghetti: 34 ± 18; penne: 38 ± 20; bread: 27 ± 13; couscous: 24 ± 17) and longer oral processing (spaghetti: 21 ± 13 s; penne: 23 ± 14 s; bread: 18 ± 9 s; couscous: 14 ± 10 s) compared with bread or couscous (P < 0.01). Pastas contained more large particles (46–67% of total particle area) compared with bread (0–30%) and couscous (1%) after mastication and in vitro gastric digestion. After in vitro gastric digestion, pasta samples still contained large areas of nonhydrolyzed starch embedded within the protein network; the protein in bread and couscous was almost entirely digested, and the starch was hydrolyzed. Conclusions Preservation of the pasta structure during mastication and gastric digestion explains slower starch hydrolysis and, consequently, lower postprandial glycemia compared with bread or couscous prepared from the same durum wheat semolina flour in healthy adults. The postprandial in vivo trials were registered at clinicaltrials.gov as NCT03098017 and NCT03104686.

Oral impairments decrease the nutrient bioaccessibility of bread in the elderly

“…These boluses are obtained as a consequence of deficient mastication and are frequently noted in elderly people with impaired dental status and oral functions (Peyron et al, 2021). Similar results with bread were observed by Vanhatalo et al (2022), who performed a mastication trial involving 26 normal-weight adults. Moreover, the proportion of large particles significantly increased when simulating saliva reduction together with loss of force, which lowers the exchanges between bread boluses and saliva and impedes or delays the initiation of oral digestion of starch (Alam et al, 2019;Blanquet-Diot et al, 2021;Bornhorst, Kostlan, & Singh, 2013).…”

“…Nevertheless, the in vitro bread boluses obtained after mimicking deficient mastication showed larger and more compact particles than normal masticated bread boluses. The quantity of salivary α-amylase in a food bolus is crucial for the overall breakdown of starch in starch-based products as breads (Bornhorst & Singh, 2012;Vanhatalo et al, 2022). The larger particles noted in poorly fragmented boluses might impair the access of salivary α-amylase to starch granules, impeding or delaying oral digestion of starch and D-glucose release.…”

Associations between oral processing, saliva, and bolus properties on daily glucose excursions amongst people at risk of type-2 diabetes

“…In addition, longer chewing duration leads to an increase in the number of food particles that are smaller in size and a larger bolus surface area, which stimulates more saliva production and greater saliva uptake by bolus particles. 8,22 Previous studies have reported that starch digestion increases when food particle size reduces and bolus surface area increases, 10,38 which stimulates greater amylase activity and early glucose release. Experiments on mixed meal tolerance test demonstrated that increasing mastication supports early glucose release and stimulates insulin secretion, 10,16 which suggests that greater bolus saliva uptake could change the kinetics of glucose release and may aid insulin release 8 .…”

“…10,20 The sizes of formed bolus particles have also been shown to influence postprandial response, whereby smaller food bolus particles led to a higher blood glucose response among healthy individuals. 21,22…”

“…10,20 The sizes of formed bolus particles have also been shown to influence postprandial response, whereby smaller food bolus particles led to a higher blood glucose response among healthy individuals. 21,22 Less is known about whether oral processing behaviours, bolus and saliva properties are associated with habitual daily glucose excursions among individuals at a higher risk of T2D. The impact of oral processing on glucose release over time has been studied acutely in healthy and diabetic populations using a CGM following an acute fixed carbohydrate test meal.…”