|M.Sc Student||Patricia Zimet|
|Subject||Milk Protein Based Nano-Vehicles for Omega 3-Polyunsaturated|
|Department||Department of Biotechnology and Food Engineering||Supervisor||Professor Livney Yoav|
|Full Thesis text|
Numerous studies have shown the health benefits of essential omega-3 polyunsaturated fatty acids (ω-3 PUFA), such as docosahexaenoic acid (DHA, 22:6). The trend for reduction of fat consumption calls for the enrichment of non-fat or low-fat foodstuffs with such essential nutraceuticals. New technologies are required to achieve this without compromising the sensory properties of the enriched product, because these compounds have low water-solubility and high sensitivity to oxidation.
The overall goal of this study was to develop stable nano-vehicles that would solubilize, protect and possibly improve the bioavailability of DHA. Two systems were investigated: complexes of β-Lactoglobulin (β-Lg) and pectin for enrichment of clear, acid, aqueous foodstuffs, and the formation of re-assembled casein micelles (rCM) for enrichment of dairy products.
Beta-Lg is a small whey protein that can bind certain hydrophobic molecules. The present work provided first evidence for the binding (Kb= (6.75±1.38)*105 M-1) of DHA to β-Lg. In addition, colloidally stable nano-complexes of DHA-loaded β-Lg and low methoxyl pectin were formed at pH=4.5, by adding excess of pectin. Dilutable dispersions were formed, which yielded transparent solutions at a 1:2 (β‑Lg:DHA) molar ratio, with a very good colloidal stability and average particle size of ~100 nm. The entrapment of DHA by these β-Lg/pectin complexes provided good protection against its degradation: during an accelerated shelf-life test, only 5-10% DHA were lost when nano-encapsulated, compared to about 80% loss of unprotected DHA.
Caseins, on the other hand, comprise about 80% of cow-milk proteins and consist of four main proteins: αs1-, αs2-, β- and κ-casein. Their biological function is to transport calcium, protein and phosphate from the mother to the neonate. Caseins have a very strong tendency to associate into colloidal particles known as micelles. This study showed the formation of stable DHA-loaded nano-particles at a 1:1 (caseinate:DHA) molar ratio. When calcium and phosphate were added, nano-particles formed were 50-60 nm. In a different process, which did not include calcium and phosphate addition, 90 and 300 nm particles were obtained. Both systems conferred excellent protection to DHA against its degradation.
In conclusion, this research suggested that nano-vehicles made of milk proteins, possibly with the addition of polysaccharides, present an innovative technology to enrich non- or low fat foodstuffs with DHA.