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Context

Ensuring good nutrition in the elderly is a real challenge. The development of new, nutritionally sound foods that are suitable for this specific population is particularly complex. Addressing this challenge requires studies that are more mechanistic, and which include the entire digestive process, under wellcontrolled conditions, made possible by the design of in-vitro devices such as the AM2 masticator and the DIDGI digester. Developing food products that are both nutritious and functional remains a crucial objective. Elderly people need foods with specific textures adapted to their oral and digestive capacities. To answer this question, we considered all the data from the oral phase, the digestive physiology of the elderly, and the modelling of the fate of protein in the stomach. Objectively assessing the bioavailability of nutrients at all stages of digestion and identifying protein profiles will ultimately make it possible to design foods that meet nutritional needs.

Results

A pork sausage model was developed and subjected to normal and deficient chewing in order to mimic the oral deficiencies commonly seen in the elderly, followed by in-vitro gastric digestion, mimicking the digestive tract of adult and elderly foods. Food boluses were characterised for their particle size and rheological properties. The kinetics of nutrient release and peptidomic analysis in the digesta were studied to establish a nutrient bioavailability index to help assess the effects of malnutrition on health status on older people. After impaired chewing, the food bolus was harder, with more coarse particles, lower free iron release and higher protein oxidation. The amount of peptides released in the stomach gradually increased, but to a lesser extent under the digestive conditions of the elderly. One novel finding was that the overall average amount of protein in the stomach after complete digestion was significantly lower in the case of impaired chewing in both adults and the elderly. Two models of the kinetics of protein hydrolysis were proposed with specific parameters for digestion in adults and the elderly.

Future outlook

Our research broadens the concept of food oral processing (FOP) by extending oral activity to digestion in a nutritional context. This new concept is called food oral and digestive processing (FODP).