Stability and behavior of omega-3 food emulsions

M. S. ÁLVAREZ CERIMEDO; MARÍA L HERRERA

Fish Oil : Production, Consumption and Health Benefits

NOVA Science Publishers

Lugar: New York; Año: 2012; p. 209 - 232

N-3 Polyunsaturated fatty acids have been shown to have potential beneficial effects for chronic diseases including cancer, insulin resistance and cardiovascular disease. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in particular have been studied extensively. In some diets, such as the typical North American diet, intakes of EPA and DHA are typically very low. The fish oil used in this study is a commercial ingredient for the food industry. It is a concentrate from fish oil, mainly salmon, which is recommended for formulation of functional foods such as chocolate, yogurt, jam, pastry filling, salad oil, mayonnaise and dressings. The use of this oil permits food manufacturers to ensure a controlled content of omega-3, EPA, DPA and DHA fatty acids, in the final products and supplies vitamin E. Thus, regarding some of these applications it is very interesting to study its behavior in emulsion systems. In the food industry, stabilization of emulsions is obtained by the addition of proteins. Sodium caseinate is a well-used ingredient because of its functional properties: good solubility and emulsifying properties, high stability during heating, water and fat-binding, thickening and gelation. The addition of this protein has a double stabilizing effect since it provokes together with other added surfactants an increase of both viscosity of the continuous phase and stability of the interface. The physicochemical properties of emulsions play an important role in food systems as they directly contribute to texture, sensory and nutritional properties of food. One of the main properties is stability which refers to the ability of an emulsion to resist changes in its properties over time. Physical instability results in an alteration in the spatial distribution or structural organization of the molecules. Creaming, flocculation, coalescence, partial coalescence, phase inversion, and Ostwald ripening are examples of physical instability. It is important for food scientists to identify the relative importance of each mechanism, the relationship between them, and the factors that influence them, so that effective means of controlling the stability and physicochemical properties of emulsions can be established. Turbiscan MA 2000 is one of the methods used to study emulsion stability. It is a vertical scan analyzer which allows the optical characterization of any type of dispersion. The reading head is composed of a pulsed near-IR light source and two synchronous detectors: the transmission and the backscattering detectors. The backscattering and transmission profiles as a function of the sample height allow following the physical evolution of this process without disturbing the original system and with good accuracy and reproducibility. Thus, by repeating the scan of a sample at different time intervals, the stability or the instability of dispersions can be study in detail. The profiles allow calculation of either creaming, sedimentation, or phase separation rates, as well as flocculation, and the mechanism making the dispersion unstable can be deduced from the transmission or the backscattering data. The aim of the present work was to investigate the effect of oil-to-protein ratio, sugar concentration on the stability of emulsions formulated with concentrated fish oil as fat phase. Creaming and flocculation kinetics were quantified analyzing the samples with a Turbiscan MA 2000.