Recently, the international food journal "Food & function" published a new cover article titled "lactoferrin based nanoemulsions to improve the physical and chemical stability of omega-3 fatty acids" by researchers from the University of Minio, Portugal.
As an essential fatty acid (FA), omega-3 polyunsaturated fatty acids contain eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Studies have shown that EPA and DHA can improve cardiovascular health, reduce inflammation, improve cognitive function and promote better development of nervous system and vision; they are also positively related to the inhibition and treatment of some diseases, including diabetes, Alzheimer's disease, allergy, arthritis, asthma and some cancers. Considering their value, the food industry is increasingly interested in increasing the level of ω - 3 PUFAs in food. However, one of the main problems of adding ω - 3 PUFAs into food is its high oxidation, which can affect the quality of food, bring about negative sensory characteristics related to oxidation and corruption, and lead to the decline of consumers' acceptance of food. In order to reduce the oxidation of ω - 3, the encapsulation process has been widely used. In recent years, for the encapsulation of lipophilic bioactive compounds, emulsions, especially O/W nanoparticles, play an important role in the food industry.
Lactoferrin plays an important role in the defense system because of its antimicrobial, antiviral and antioxidant activities. Previous studies have shown that lactoferrin has excellent emulsifying capacity, and the size of the water in oil emulsion is small, and the emulsion system is quite stable. Lactoferrin can increase the chemical stability of emulsion, whether it is added to the emulsion or deposited on the surface of O/W. Encapsulation technology, such as emulsification, is often used in combination with drying technologies such as spray drying and freeze-drying, thus inhibiting chemical or biological decomposition, enhancing the stability of suspension and prolonging the shelf life of food.
The purpose of this study is to develop a nano emulsion of encapsulated Omega -3PUFA lactoferrin and evaluate its physical and chemical stability under different production and storage conditions. Meanwhile, the effect of encapsulated Omega -3 PUFA lactoferrin nanoemulsion on cell viability was analyzed. Finally, the physicochemical properties of nano emulsion after two different drying methods (freeze-drying and spray drying) were investigated.
In this study, lactoferrin with different concentrations (0.2% to 4% w/w) was used as emulsifier. High energy method (high speed dispersing machine and high pressure homogenizer) was used to produce lactoferrin emulsion which encapsulated Omega -3PUFA, and the physical and chemical stability of nano emulsion were described at 4 and 25 degrees Celsius.
The results show that different concentrations of lactoferrin affect the size of nano emulsion, and higher concentration of lactoferrin can reduce the particle size of nano emulsion. The results showed that the nanoemulsion was stable after 69 days at 4 C and was unstable at 25 C. At 4 and 25 degrees Celsius, the scavenging capacity of the nanoemulsion was not limited, while the oxidation property increased significantly. In vitro release at 37 C showed that Omega -3 was released slowly under pH2 after encapsulation of lactoferrin, and released rapidly under pH 7.4. MTT colorimetric results revealed that the 2% (w/w) lactoferrin nanoemulsion encapsulated 12.5 g/mL -3 was non-toxic to Caco-2 cells. The researchers selected nano emulsions with high physical and chemical stability, and then dried them with two different drying methods (freeze drying and spray drying). FTIR-ATR, Raman and CD analysis showed that the structure of lactoferrin changed after drying.
This research provides us with important information about the design of nanoemulsion, and the drying technology helps the encapsulation of lipophilic compounds, so that it can be applied in food and medicine fields.
Original link: https://doi.org/10.1039/c9fo02307k
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