Compact structure and proteins of pasta retard in vitro digestive evolution of branched starch molecular structure

The roles that the compact structure and proteins in pasta play in retarding evolution of starch molecular structure during in vitro digestion are explored, using four types of cooked samples: whole pasta, pasta powder, semolina (with proteins) and extracted starch without proteins. These were subjected to in vitro digestion with porcine alpha-amylase, collecting samples at different times and characterizing the weight distribution of branched starch molecules using size-exclusion chromatography. Measurement of alpha-amylase activity showed that a protein (or proteins) from semolina or pasta powder interacted with alpha-amylase, causing reduced enzymatic activity and retarding digestion of branched starch molecules with hydrodynamic radius (R-h) 100 nm. (C) 2016 Elsevier Ltd. All rights reserved

Combined techniques for characterising pasta structure reveals how the gluten network slows enzymic digestion rate

The aim of the present study is to characterise the influence of gluten structure on the kinetics of starch hydrolysis in pasta. Spaghetti and powdered pasta were prepared from three different cultivars of durum semolina, and starch was also purified from each cultivar. Digestion kinetic parameters were obtained through logarithm-of-slope analysis, allowing identification of sequential digestion steps. Purified starch and semolina were digested following a single first-order rate constant, while pasta and powdered pasta followed two sequential first-order rate constants. Rate coefficients were altered by pepsin hydrolysis. Confocal microscopy revealed that, following cooking, starch granules were completely swollen for starch, semolina and pasta powder samples. In pasta, they were completely swollen in the external regions, partially swollen in the intermediate region and almost intact in the pasta strand centre. Gluten entrapment accounts for sequential kinetic steps in starch digestion of pasta; the compact microstructure of pasta also reduces digestion rates

On the use of marker data to determine the kinetics of the digestive behaviour of feeds

A model of the transport process that follows the progress of digesta successively through the small intestine of a monogastric is investigated. The process is multi-phase and multi-constituent, as described in detail by Bastianelli et al. [J. Anim. Sci., 74:1873–1887, 1996]. The model describes the movement of marker substances that are used to obtain data on the interactions between the intestinal sections and digesta with differing levels of soluble fibre. A multi-stage process is modelled by a set of coupled first order linear differential equations. Solutions of steady and initial value problems provide information on the transfer rates of the processes. Properties of the solutions as functions of system parameters are examined. References M. Renton, J. Hanan and K. Burrage, Using the canonical modelling approach to simplify the simulation of function in functional-structural plant models. New Phytologist, 166:845–857, 2005. doi:10.1111/j.1469-8137.2005.01330.x D. Bastianelli, D. Sauvant and A. Rerat, Mathematical modeling of digestion and nutrient absorption in pigs. J. Animal Science, 74:1873–1887, 1996. http://www.journalofanimalscience.org/content/74/8/1873.abstract R. G. Lentle and P. W. M. Janssen, Manipulating Digestion with Foods designed to Change the Physical Characteristics of digesta. Critical Reviews in Food Science and Nutrition, 50:130–145, 2010. doi:10.1080/10408390802248726 J. France, J. H. M. Thornley, M. S. Dhanoa and R. C. Siddons, On the mathematics of digesta flow kinetics. Journal of Theoretical Biology, 113:743–758, 1985. doi:10.1016/S0022-5193(85)80191-0 A. Mazanov and J. V. Nolan, Simulation of the dynamics of nitrogen metabolism in sheep. British Journal of Nutrition, 35:149–174, 1976. doi:10.1079/BJN19760017 A. Mazanov, Stability of Multi-pool Models with Lags. Journal of Theoretical Biology, 59:429–442, 1976. doi:10.1016/0022-5193(76)90181-

The role of thermostable proteinaceous α-amylase inhibitors in slowing starch digestion in pasta

Starch in pasta is slowly digested, which is nutritionally advantageous because it reduces post-prandial glycemia, a risk factor for type 2 diabetes. We examine the role of proteinaceous amylase inhibitors, providing insights into how wheat proteins slow starch digestion. Gluten samples were extracted in the laboratory and also commercially obtained, and incubated in water at 37 °C and 100 °C. The centrifuged supernatant and gluten pellet were incubated with porcine α-amylase, and enzymatic activity measurement revealed that the supernatant from gluten heated to 100 °C retained the capacity to significantly reduce amylolytic activity. Confocal microscopy showed that the gluten pellet had become porous following heat treatment. These results are consistent with an increased concentration of soluble proteins after cooking. Proteins in the soluble fraction and gluten pellet were identified with mass spectrometry proteomics, which screened a limited number of endogenous double-headed α-amylase/trypsin inhibitors (α-AI(s)), found to be enriched in the supernatant after cooking. Endogenous α-AI(s) play a role in slowing starch digestion by interacting with α-amylase as it penetrates the gluten network that entraps the starch, resulting in an immobilization of the enzyme onto the gluten network, so that the digestion of starch entrapped by the gluten network is inhibited