ABSTRACT
Table 2.2 (Continued) Physicochemical Properties of Selected Lipophilic Components Claimed to Have Health Benefits When Used as Nutraceuticals
2.2.1 Neutral Oils Neutral oils can be considered to be lipids that have little flavor or color of their own. This type of lipid is added to many types of aqueous-based product to alter their physicochemical and sensory attributes in a way that makes them more palatable or desirable to consumers. For example, in emulsion-based products, neutral oil droplets provide a turbid or creamy appearance (because of light scattering), viscosity and mouthfeel enhancement (because of their impact on fluid flow), and flavor alterations (because of their ability to solubilize nonpolar flavors) (McClements 2005). In addition, neutral oils may also act as carriers for other nonpolar components in foods, such as oil-soluble pigments, preservatives, vitamins, and nutraceuticals. The neutral oils used for this purpose are usually high-molecular-weight molecules with extremely low water solubilities, such as triacylglycerols or terpene oils (Figure 2.1). Triacylglycerols are typically derived from natural sources such as animals (e.g., fish, meat, and milk), plants (e.g., canola, corn, rapeseed, olive, safflower, and sunflower), and microorganisms (e.g., algae) (Akoh and Min 2008), whereas terpenes are usually isolated by distillation of natural oils from plant sources, such as fruits, vegetables, leaves, herbs, and spices (Burt 2004). Because of their low water solubilities, these oils usually need to be encapsulated in a suitable form before they can be readily dispersed into aqueous-based food or beverage products. The most commonly used encapsulation technology for this type of lipid is oil-in-water emulsions (Given 2009), but other kinds of colloidal delivery systems can also be used to gain specific functional attributes, such as nanoemulsions, solid lipid nanoparticles, multilayer emulsions, or multiple emulsions (McClements 2012a). The formation and stability of colloidal delivery systems based on neutral oils depend on their polarity, phase behavior, viscosity, interfacial tension, and density (McClements 2005).
