Relationships between saliva and food bolus properties from model dairy products

During food consumption, complex oral processing occurs to transform the food into a bolus, ready to be swallowed. The objective of this study was to relate food, saliva and bolus properties, by using model dairy products, to better understand the role of saliva in bolus formation. Un-stimulated and stimulated saliva was collected from 5 subjects and biochemical and enzymatic properties were measured. Food bolus was then obtained from 8 different dairy products, varying in composition and ranging from liquid to gelled samples. The rate of saliva incorporation, pH, spreading ability and bolus rheological properties were determined. Some correlations seemed to exist between lysozyme activity and bolus properties. Subject and food product had a significant effect on almost all bolus properties. The rheology of bolus was highly correlated with food product texture. Even though preliminary, this approach could be used to better understand stimulus release and perception during food consumption.     

Food oral processing: Mechanisms and implications of food oral destruction

BackgroundFood oral processing is a simultaneous process of food destruction and sensory perception. How a food breaks down its structure inside the mouth and what mechanisms control this process are hugely important to our eating experience and sensory perception. A proper understanding of this process is urgently needed by the food industry for better design and manufacturing of quality tasty food.Scope and approachThis review article analyses research findings from literature and from author's own laboratory in order to identify main controlling mechanisms of food oral destruction. Appropriate experimental evidences are given wherever available to demonstrate the important implications of different destruction mechanisms to sensory perception.Key findings and conclusionsThree major controlling mechanisms of food oral destruction are identified: the mechanical size reduction, the colloidal destabilisation, and the enzymatic interactions. These mechanisms may be applicable to different food materials either independently or collectively. They could also be applicable through the whole eating process or just at a certain stage of an eating process.     

The influence of oral lubrication on food intake: A proof-of-concept study

As overeating, overweight and obesity remain public health concerns, it is crucial to design satiety-enhancing foods that suppress appetite and lower snack intake. Existing research identifies oro-sensory targets to promote satiation and satiety, yet it remains unclear as to whether it is ‘chewing’ or ‘oral lubrication’ that might amplify satiation signals. In this study, techniques from experimental psychology, food material science and mechanical engineering have been combined to develop model foods to investigate the role of chewing and oral lubrication on food intake. Novel model gels, similar in pleasantness, were given as a preload then their effects on subjective appetite and intake of a salty snack were measured in a between-subjects design. Three mint flavoured hydrogels were engineered to vary in their texture (fracture stress) and lubrication (inverse of coefficient of friction), and a control group received mint tea. Results showed that snack intake was suppressed by 32% after eating the low chewing/high lubricating preload compared to the high chewing/low lubricating preload (p < 0.05). Hunger ratings decreased from t₁ to t₃ (p < 0.05), however differences between conditions were subtle and not significant. Thus, this proof-of-concept study demonstrates that manipulating oral lubrication is a promising new construct to reduce snack intake that merits future research in the oro-sensory satiety domain.     

Effect of Food Matrix on Saltiness Perception—Implications for Sodium Reduction

Enhancing sodium release from the food matrix, thus increasing saltiness perception, is a promising strategy to reduce the amount of salt needed in foods. However, the complex nature of the effect of the food matrix on saltiness perception makes it difficult to control saltiness perception when designing food products. The aim of this review is to provide an overview of the food matrix effects on saltiness perception of sodium chloride. The effects are discussed in the order of 3 stages in saltiness perception: release of sodium from food matrix into oral cavity (1st stage), delivery of sodium within oral cavity (2nd stage), and detection of sodium by the taste receptor cells (TRCs) (3rd stage). In the 1st stage, the food matrix affects the initial availability of sodium to be released, and also affects the spontaneous and facilitated migration of sodium from the matrix into the oral cavity. In the 2nd stage, the food matrix affects the availability of sodium and the mixing efficiency of sodium with saliva. The relationship between food matrix and oral processing of food that may affect the sodium release (1st stage) and the delivery (2nd stage) is also discussed. In the 3rd stage, the food matrix affects the physical availability of sodium for the TRCs, the physiological activity of TRCs, and the central activities involved in the perception process. Based on the understanding of complex nature of the matrix effects on saltiness perception discussed in this review, the properties of food matrix may be controlled effectively to enhance saltiness perception and achieve sodium reduction.     

Food emulsions as delivery systems for flavor compounds: A review

Food flavor is an important attribute of quality food, and it largely determines consumer food preference. Many food products exist as emulsions or experience emulsification during processing, and therefore, a good understanding of flavor release from emulsions is essential to design food with desirable flavor characteristics. Emulsions are biphasic systems, where flavor compounds are partitioning into different phases, and the releases can be modulated through different ways. Emulsion ingredients, such as oils, emulsifiers, thickening agents, can interact with flavor compounds, thus modifying the thermodynamic behavior of flavor compounds. Emulsion structures, including droplet size and size distribution, viscosity, interface thickness, etc., can influence flavor component partition and their diffusion in the emulsions, resulting in different release kinetics. When emulsions are consumed in the mouth, both emulsion ingredients and structures undergo significant changes, resulting in different flavor perception. Special design of emulsion structures in the water phase, oil phase, and interface provides emulsions with great potential as delivery systems to control flavor release in wider applications. This review provides an overview of the current understanding of flavor release from emulsions, and how emulsions can behave as delivery systems for flavor compounds to better design novel food products with enhanced sensorial and nutritional attributes.