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Abstract
This study was designed to explore the possible use of Ý-casein in nanoencapsulation of CLA and use of the encapsulated CLA in the fortification of yoghurt. Rennet casein was prepared by chymosin coagulation of cow, buffalo, camel and goat skim milks. Ý-casein was separated from the prepared rennet caseins. Conjugated linoleic acid (CLA) was prepared by alkali isomerization of pure linoleic acid. Different concentrations namely 25, 50, 75 and 100 mg/100 mg Ý-casein of CLA were loaded in the different Ý-caseins and the encapsulation efficiency was determined for the obtained capsules. Ý-nanocasein particle and Ý-nanocasein particle loaded with CLA properties were studied. Cow{u2019}s Ý-nanocasein particle loaded with CLA at 75 mg/ 100 mg Ý-casein was used in the fortification. Buffalo{u2019}s yoghurt at three levels 200, 400 and 600 mg nanoparticale loaded with CLA / 100 ml milk. The yoghurt was stored for 10 days and its properties were studed during storage. The obtained results summarized that cow{u2019}s, buffalo, camel and goat Ý-casein showed high encapsulation efficiencies for CLA. The highest efficiency was recorded with camel milk. Ý-casein from studied sources showed the same critical micelle concentration of 10 mg. CLA loaded nanoparticale from different Ý-caseins showed a maximum absorption at 233 nm, the characteristic wavelength for dienes. CLA was extracted from CLA loaded Ý-caseins nanoparticle using ethanol. Measurement was done at 233 nm (indirect method). It was proved that direct method was rapid, simple and determine CLA without solvent extraction. Loading CLA increased variability the zeta potential of CLA loaded Ý-casein nanoparticles to -57.4 ±4.6, -55.2±3.83, -51.2±8.9 and 48.8±12.6 mV for cow, buffalo, camel and goat respectively. Addition of CLA capsules increased markedly the conjugated dienes content of yoghurt. In conclusion, yoghurt of acceptable quality, oxidative stability, rich in conjugated dienes can be made by fortification of yoghurt with 0.2% CLA capsules