Impact of the oil droplet size on the oxidative stability of microencapsulated oil

Influence of emulsifier on lipid oxidation in spray-dried microencapsulated O/W emulsions

Lipid oxidation limits the shelf-life of dried microencapsulated oils (DMOs), such as infant formula. However, it is poorly understood how lipid oxidation is affected by different types of emulsifiers. To improve our understanding, we prepared DMOs with different emulsifiers (whey protein isolate (WPI), pea protein isolate (PPI), and non-proteinaceous CITREM) and studied lipid oxidation in both the free and encapsulated fat. Only a small difference in oxidation rate was observed between these fat fractions for all formulations. We ascribed this to a non-discrete distribution of the fractions and the subsequent low fractionation selectivity as shown by Raman microscopy. The DMO with PPI showed hardly any oxidation during a 7-week incubation at 40 °C, whereas the DMOs with WPI and CITREM both reached significantly higher contents of oxidation products (lipid hydroperoxides, aldehydes, and epoxides). The enhanced stability of DMO-PPI could not be ascribed to the presence of phytic acid. In conclusion, we demonstrate the potential of using PPI to produce oxidatively stable DMOs.

Lipid oxidation in emulsions and bulk oils: a review of the importance of micelles

Lipid oxidation is a major cause of quality deterioration in food products. In these foods, lipids are often present in a bulk or in emulsified forms. In both systems, the rate, extent and pathway of oxidation are highly dependent on the presence of colloidal structures and interfaces because these are the locations where oxidation normally occurs. In bulk oils, reverse micelles (association colloids) are present and are believed to play a crucial role on lipid oxidation. Conversely, in emulsions, surfactant micelles are present that also play a major role in lipid oxidation pathways. After a brief description of lipid oxidation and antioxidants mechanisms, this review discusses the current understanding of the influence of micellar structures on lipid oxidation. In particular, is discussed the major impact of the presence of micelles in emulsions, or reverse micelles (association colloids) in bulk oil on the oxidative stability of both systems. Indeed, both micelles in emulsions and associate colloids in bulk oils are discussed in this review as nanoscale structures that can serve as reservoirs of antioxidants and pro-oxidants and are involved in their transport within the concerned system. Their role as nanoreactors where lipid oxidation reactions occur is also commented.

Impact of the oil load on the oxidation of microencapsulated oil powders

The effect of the oil load on the oxidation of microencapsulated fish oil powders was investigated. The oil load was varied between 4.95 and 20.33%(w/w) by spray drying O/W emulsions with different oil to matrix ratios (0.05, 0.1, 0.15 and 0.2(w/w)), whereas solid content (45%(w/w)) and soy protein isolate to oil ratio (0.15(w/w)) were kept constant. A standardized size fraction of particles (50-80 µm) was stored for 82 days and hydroperoxides and anisidine value measured in the total- and encapsulated oil. Oxidation was limited by the oxygen amount rather than by the oil load. The absolute amount of oxidation products (per powder mass) increased with the oil load, which was explained by oxygen diffusion. Calculating oxidation products per oil mass resulted in a faster oxidation of the powder with 5% oil, whereas the oxidation rate for oil loads ≥10%(w/w) was similar, due to a scavenging effect of oil droplets.

Encapsulation of Active Ingredients in Food Industry by Spray-Drying and Nano Spray-Drying Technologies

Since its invention in 1872 by Samuel Percy, the spray drying of food products has been widely used, whether in products consumed by babies in milk formulations, powdered sweets and cocoa soluble in milk for children, or food supplements rich in proteins, vitamins, and minerals for adults. All of these products were first formulated in solution and then converted into powders to facilitate the transport and preservation of the properties during storage. In recent years, novel technologies such as nano spray drying have emerged for the development of food formulations with high-cost active ingredients. The aim of the present work is to present a review of the literature reported in the last 10 years related to these technologies. The basis of the spray-drying technologies i.e., conventional and nano, are described and compared, emphasizing the instrumental processing conditions for achieving a desired product. Examples of some unwanted reactions presented during the encapsulation of active ingredients are provided.