Home Health The Impact of Food Bioactives on Health
InfoGest Consensus Method
Alan Mackie and Neil Rigby
Abstract This section describes the consensus static digestion method developed within the COST Action InfoGest. Simulated gastro-intestinal digestion is widely employed in many fields of food and nutritional research. Various different digestion models have been proposed, which often impedes the possibility of comparing results across research teams. For example, a large variety of enzymes from different sources such as porcine, rabbit or human have been used and these differ in their activity and characterization. Differences in pH, mineral composition and digestion time that alter enzyme activity and other phenomena may also significantly alter results. Other parameters such as the presence of phospholipids, specific enzymes such as gastric lipase and digestive emulsifiers, etc. have also been discussed at length. In this section, a general standardised and practical static digestion method is given, based on physiologically relevant conditions that can be applied for various endpoints. A framework of parameters for the oral, gastric and small intestinal digestion is outlined and their relevance discussed in relation to available in vivo data and enzymes. Detailed, line-by-line guidance recommendations and justifications are given but also limitations of the proposed model. This harmonised static, in vitro digestion method for food should aid the production of more comparable data in the future.
Keywords In vitro • Digestion • Oral • Gastric • Small intestinal
The static protocol for simulating digestion in the upper GI tract published by InfoGest and led by Andre Brodkorb was the result of more than 2 years' work involving extensive discussion among scientists from a wide range of relevant disciplines (Minekus et al. 2014). The final consensus recommendation is relatively simple, based on physiological parameters that have been cited and is widely supported by those undertaking in vitro digestions, especially in food research. In keeping with the requirement for simplicity but not oversimplification discussed in the general introduction to this chapter, this is a static model using values of pH, ionic composition endogenous surfactants and enzyme activity that are fixed at the start of the experiment. All aspects of digestion in the upper GI tract were considered in the development of the method and the reasons for the inclusion or exclusion of specific features will be discussed below. The method comprises up to three stages that mimic the oral, gastric and small intestinal phases of digestion in vivo. At each stage the duration and physical and biochemical environment are described and the reasons for their selection given. The enzymes recommended for inclusion are described using their IUBMB Enzyme Nomenclature and the method has been written in such a way as to allow the sourcing of material from any suitable supplier. The method is outlined in the flow diagram given in Fig. 2.1. All enzyme activities and other concentrations are given per mL of digesta as they will finally be used.
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