Predicted glycemic index and hydrolysis index in former food products intended for pig nutrition

“Ex-food” or “Former Food Products” (FFPs) means foodstuffs, other than catering reflux, which were manufactured for human consumption in full compliance with the EU food law but which are no longer intended for human consumption. Typical former foodstuffs used by are biscuits, bread, breakfast cereals, chocolate bars, pasta, savoury snacks and sweets, all because of their high energy content in the form of sugars, oils and starch. Based on nutritional fact reported for humans, in general FFPs are extremely rich in carbohydrate, free sugars, and depending on their origin, also in fat, even though their nutritional potential is not yet fully exploited. Thus, the aim of the present study was to evaluate both the predicted glycemic index (pGI) and hydrolysis index (HI) in FFPs intended for pig nutrition. Six samples of bakery/confectionary FFPs, and two conventional feed ingredients (corn meal and flaked wheat), were analyzed using an in vitro method based on the Englyst-assay simulating gastric and small intestinal digestion for starch, and that has been proposed for predicting the glycemic index of starchy foods. White bread was used as reference material. Hydrolysis indices (HI) were calculated as a summary of the temporal glucose pattern, defined in terms of the area under the digested glucose curve for each sample. To white bread was assigned a HI of 100, while the HIs for the other samples were calculated as the area under the curve for each test material. Results have been expressed as a percentage of the mean area under the curve relative to white bread. From the HI, predicted glycemic index (pGI) was calculated for each sample using the equation reported by Giuberti (2012). Considering conventional feed ingredients, the lowest HI value was observed in corn meal (81.05) the same value was 93.59 in flacked wheat. In FFPs HI ranged from 86.01 to 113.45 with an overall mean of 104. Predicted GI values, were 82.1 in corn meal and 94.81 in flacked wheat. When FFPs were considered pGI ranged from 87.1 to 114.9, with five samples above the reference values of white bread. This indicates a higher glycemic index potential in FFPs compared to common cereals.