Role of Food Material Properties and Disintegration Kinetics in Gastric Digestion – A quest for foods for healthy benefits

The quest to manufacture foods for healthy benefits is an underpinning goal of the modern food industry. Food processing has evolved to carry out steps for the controlled destruction of natural food structures. These steps facilitate separation of valuable components from the original matrix in which they are embedded. The separated ingredients are then converted into recognizable processed foods with desirable textural and sensorial properties by application of one or more processing steps (Aguilera and Stanley, 1999). Recent evidence indicates that how the food structure breaks down during gastric digestion significantly affects the rate of uptake of nutrients in the gastrointestinal (GI) tract (Armand et al., 1999; Jarvi et al., 1995). Therefore the knowledge and any capability to predict how a food may disintegrate in the stomach are important for developing new food products with novel health benefits. Understanding the postingestion food behavior and the knowledge of the availability of nutrients and their uptake kinetics can guide food processors to select appropriate ingredients and processing conditions at the time of manufacture. The focus of the current research is on understanding this admittedly complex subject, namely, the breakdown of a food in the human stomach. Nutrient absorption in the intestines is a topic for future study. From an engineering perspective, the human stomach is a receptacle, a grinder, a mixer and a pump that controls the digestion process. One of its major functions is to reduce the size of solid particulates and fat globules. The digestion process has been well studied in terms of secretion of gastric fluids, enzymatic breakdown of fats, proteins and carbohydrates, and molecular and ionic transport across the intestinal epithelium. However, there remains a notable lack of understanding about the food disintegration kinetics and the extraction of small molecules from complex food structures in the gastric environment. Furthermore, how the changes in food texture and microstructure (that define the material properties) resulting from various food processing affect gastric disintegration of foods is lacking. Fortunately, considerable research done in the nutrition, medical and pharmaceutical field during the last 30 years provides useful information to initiate this research with a focus on foods. In the following subsections, some of the key studies done in these areas are reviewed with relevance to the current research.