Reduced-fat foods: the complex science of developing diet-based strategies for tackling overweight and obesity

Abstract

Fat plays multiple roles in determining the desirable physicochemical properties, sensory attributes, nutritional profile, and biologic response of food products. Overconsumption of fats is linked to chronic diseases, such as obesity, coronary heart disease, diabetes, and cancer. There is therefore a need to develop reduced-fat products with physicochemical properties and sensory profiles that match those of their full-fat counterparts. In addition, foods may be redesigned to increase the feelings of satiety and satiation, and thereby reduce overall food intake. The successful design of these types of functional foods requires a good understanding of the numerous roles that fat plays in determining food attributes and the development of effective strategies to replace these attributes. This article provides an overview of the current understanding of the influence of fat on the physicochemical and physiologic attributes of emulsion-based food products and highlights approaches to create high-quality foods with reduced-fat contents.

Keywords: emulsions; food design; food matrix effects; functional foods; obesity; overweight; reduced-fat; satiety.

FIGURE 1

The properties of oil-in-water emulsions depend on the characteristics of the droplets they contain (e.g., concentration, composition, particle size, physical state, and interfacial characteristics).

FIGURE 2

Overview of the relations between emulsion properties, sensory perception, and biologic response of food emulsions.

FIGURE 3

Dependence of the shear viscosity of an oil-in-water emulsion on fat droplet content. It is assumed that the fat droplets are not flocculated and that there are no thickening agents in the continuous phase.

FIGURE 4

Dependence of the lightness of an oil-in-water emulsion on fat droplet content. The lightness of an emulsion increases steeply from ∼0% to 5% fat but then increases more gradually as the fat content is increased further.

FIGURE 5

Schematic diagram of most common instability mechanisms that occur in colloidal delivery systems: gravitational separation, flocculation, coalescence, Ostwald ripening, and phase inversion.

FIGURE 6

Calculated dependence of the creaming velocity of the fat droplets in an oil-in-water emulsion on fat droplet concentration. The rate of creaming decreases with increasing fat content because of droplet-droplet interactions.

FIGURE 7

Schematic representation of the calculated dependence of the flavor intensity above an oil-in-water emulsion on fat content. Nonpolar flavors decrease in intensity as the fat content increases, whereas polar flavors increase in intensity.

FIGURE 8

The behavior of an emulsion-based product within the oral cavity depends on the nature of the particles it contains (e.g., particle concentration, composition, charge, size, and interfacial properties). Particles may adhere, coalesce, flocculate, and spread when they encounter the oral cavity depending on their properties.

FIGURE 9

The behavior of an emulsion-based product in the gastrointestinal tract plays an important role in satiety/satiation and delivery of nutrients. Emulsified TGs are digested by lipases; the resulting FAs are incorporated into mixed micelles, then absorbed by epithelium cells, and may be reassembled into chylomicrons before entering the systemic circulation.

FIGURE 10

Schematic representation of changes in hunger and fullness responses before, during, and after consumption of a meal. The peptides associated with these responses and their interactions with the brain are also shown. CCK, cholecystokinin; GLP-1, glucagon-like peptide 1; OXM, oxyntomodulin; PYY, peptide YY.

FIGURE 11

The stability of fat droplets to sedimentation and creaming in the stomach may alter gastric emptying because the body detects the energy density of the food leaving the stomach. This mechanism has been proposed as a means of controlling satiety.

FIGURE 12

Some of the desirable food attributes provided by fat droplets (opacity, texture, and mouthfeel) can be provided by polymeric or particulate substances, such as thickening agents, hydrogel particles, indigestible fat droplets, starch granules, titanium dioxide, or protein particles.

FIGURE 13

Structural design principles may be used to create reduced-fat emulsion-based products with physicochemical attributes similar to conventional products.