Evolutions of rheology, microstructure and starch hydrolysis of pumpkin‐enriched bread during simulated gastrointestinal digestion

Abstract

In this study, the influences of pumpkin flour additions to breadmaking on evolutions of microstructure, rheology and starch hydrolysis during simulated gastrointestinal digestion were investigated. Compared to white bread (PB0), the bread supplemented with 20% pumpkin flour (PB20) showed more continuous and fibrous gel network structure with most starch granules encapsulated in the network throughout the in vitro digestion. Due to the dilution of digestive fluids and enzymatic hydrolysis, the digesta moduli and viscosity remarkably decreased as time progressed, but PB20 presented significantly higher rheology compared to PB0 in each digestion phase. At the end of intestinal phase, the in vitro starch digestibility was 69.9% for PB0, significantly higher than that for PB20 (55.4%). This is presumably attributed to the abundant dietary fibre in pumpkin flour, contributing to the increased digesta viscosity and the formation of more compact and stable gel networks that would hinder the contact of starch granules with α‐amylase. In addition, the pumpkin‐added breads gave satisfactory results in terms of sensory acceptability. This study has suggested promising potential of incorporating pumpkin flour in the production of functional bakery products with reduced starch digestibility while maintaining good sensory characteristics.

Impact of amylose from maize starch on the microstructure, rheology and lipolysis of W/O emulsions during simulated semi‐dynamic gastrointestinal digestion

“…The G″ of control emulsions remained dominant (G″ > G′) during the initial, gastric and small intestinal phases, exhibiting fluid‐like behaviour (Fig. 5a) (Iqbal et al ., 2019; Ge, Iqbal, et al ., 2021; Ge, Wu, et al ., 2021). G′ remained dominant at low applied frequency ranges in NAM emulsion digesta (≈0.1–0.6 rad s −1 ).…”

“…Optical and confocal microscopy were used to investigate the microstructure and the location of water droplets throughout the oil phase before and after GIT digestion. For optical microstructures, an Olympus CX‐31, Olympus Optical Co., Ltd., Japan, with a 40× objective lens was utilised to examine the microstructures of Control, NAM and HAM emulsions before and within the simulated GIT digestion (oral, gastric and small intestinal phases) (Ge, Iqbal, et al ., 2021; Ge, Wu, et al ., 2021).…”

“…The droplet size of W/O emulsions before and after the GIT digestive phases was determined by using a laser diffraction particle size analyser (Partica, Horiba, LA‐960, Kyoto, Japan). Refractive indices of the oil and water phases were retained at 1.47 and 1.33 respectively (Ge, Iqbal, et al ., 2021; Ge, Wu, et al ., 2021).…”

“…Water-in-oil emulsions Three kinds of W/O emulsions were prepared by homogenising 40 wt.% (80 g) of the aqueous phase throughout the oil phase (60 wt.%, 120 g). For this purpose, oil and aqueous phases were subjected to a container, followed by homogenisation (at 3000 rpm for 2 min) to achieve primary (coarse) emulsion, using a high shear mixer (T18 digital Ultra Turrax ® , IKA works Inc., Wilmington, NC, USA) (Ge, Iqbal, et al, 2021;Ge, Wu, et al, 2021). The resulting primary emulsions were then emulsified for three cycles at 414 bar by using a high-pressure homogeniser (AH-Basic Plus, HNHM, ATS Engineering Inc., Suzhou, China).…”

Impact of oleuropein on rheology and breadmaking performance of wheat doughs, and functional features of bread

“…Recently, Ge et al . (2021) reported that the addition of different amounts of pumpkin powder, rich in dietary fibre and bioactive compounds, reduced bread‐specific volumes and originated more compact structures which encapsulated starch granules, retarding starch digestion. Moreover, gluten‐free breads with more compact structure showed reduced in vitro glycaemic responses (De La Hera et al ., 2014; Carini et al ., 2015).…”