166 The nutrition handbook for food processors experimental design to a few foods and conditions, and apart from effects on nutrient levels measured in standard food analyses, nutritional information that reflects the effects of processing does not generally reach consumers in a form in which it can be widely used to choose foods. Similarly, food processors often do not have available means to apply, either accurately or practically, relevant nutritional criteria to select prototype products during development. Below are listed several reasons for the need for new nutritional information 7.2.1 Showing effects of food properties on nutritional qualities Much of the impact of processing on nutritional quality comes about through changes in physicochemical properties of food polymers, such as dietary fibre, hat cannot be represented by food composition values. Changes in structure asso- ciated with such processes as starch hydration and gelatinisation, milling, and extrusion,can have an large impact on the rate and extent of digestion, and onsequently on a range of physiological markers linked to disease end-points For example, the impact of cereals on blood glucose and insulin responses is increased markedly as particle size is reduced by milling, or as starch is 7.2.2 Tracking changes in nutritional quality Information from rapid, valid, but relevant tests is needed to guide processing to healthy products. Because of the expense, time, ethics, compliance and other issues involved in clinical trials, human subjects are not usually suitable for mon- oring effects of processing until potential products have been identified Food processing for improved nutrition may require pragmatic choice of dif- ferent tests at different stages in product development, to maintain momentum in product development. Active ingredients and formulations may be identified with screening tests, using indirect predictors of health effects, such as ingredient prop- erties. Responses in animal models may guide food processing further, and most promising products then taken into clinical trials, in which effects on biomarkers with established links to health end-points are measured, before a claim of efficacy is made. Increasing rigour in nutritional evaluation of functional prop. erties during the course of product development is illustrated in Table 7.1 As a general principle, the properties of foods that affect physiology should be measured under conditions as close as is reasonable to those in which the food property acts in vivo. Developing a soluble fibre-enriched product to lower blood cholesterol is an example. Ingredients of high soluble fibre content could be iden tified using soluble fibre analysis under simulated gastrointestinal conditions. 12 As hypocholesterolaemic effects of soluble dietary fibres result from increased intestinal viscosity, fibre viscosity should be measured, followed by in vitro digestion of products containing selections of viscous fibre sources, with mea surement of digesta viscosity. Promising products could be subjected to animal trials to establish that predicted gut viscosity and blood lipid changes occurexperimental design to a few foods and conditions, and apart from effects on nutrient levels measured in standard food analyses, nutritional information that reflects the effects of processing does not generally reach consumers in a form in which it can be widely used to choose foods. Similarly, food processors often do not have available means to apply, either accurately or practically, relevant nutritional criteria to select prototype products during development. Below are listed several reasons for the need for new nutritional information. 7.2.1 Showing effects of food properties on nutritional qualities Much of the impact of processing on nutritional quality comes about through changes in physicochemical properties of food polymers, such as dietary fibre,5 that cannot be represented by food composition values. Changes in structure asso￾ciated with such processes as starch hydration and gelatinisation,6 milling,7 and extrusion,8 can have an large impact on the rate and extent of digestion, and consequently on a range of physiological markers linked to disease end-points. For example, the impact of cereals on blood glucose and insulin responses is increased markedly as particle size is reduced by milling,7 or as starch is gelatinised.6,9 7.2.2 Tracking changes in nutritional quality Information from rapid, valid, but relevant tests is needed to guide processing to healthy products. Because of the expense, time, ethics, compliance and other issues involved in clinical trials, human subjects are not usually suitable for mon￾itoring effects of processing until potential products have been identified. Food processing for improved nutrition may require pragmatic choice of dif￾ferent tests at different stages in product development, to maintain momentum in product development. Active ingredients and formulations may be identified with screening tests, using indirect predictors of health effects, such as ingredient prop￾erties. Responses in animal models may guide food processing further, and most promising products then taken into clinical trials, in which effects on biomarkers with established links to health end-points are measured,10,11 before a claim of efficacy is made. Increasing rigour in nutritional evaluation of functional prop￾erties during the course of product development is illustrated in Table 7.1. As a general principle, the properties of foods that affect physiology should be measured under conditions as close as is reasonable to those in which the food property acts in vivo. Developing a soluble fibre-enriched product to lower blood cholesterol is an example. Ingredients of high soluble fibre content could be iden￾tified using soluble fibre analysis under simulated gastrointestinal conditions.12 As hypocholesterolaemic effects of soluble dietary fibres result from increased intestinal viscosity,13 fibre viscosity should be measured, followed by in vitro digestion of products containing selections of viscous fibre sources, with mea￾surement of digesta viscosity. Promising products could be subjected to animal trials to establish that predicted gut viscosity and blood lipid changes occur 166 The nutrition handbook for food processors