Fish oil encapsulated in soy protein particles by lyophilization. Effect of drying process.

BACKGROUND: Fish oil is an important source of healthy ω-3 fatty acids to be used in functional foods. However, its autoxidation susceptibility, aroma and solubility make it difficult to use. Its encapsulation could reduce these disadvantages. This manuscript focuses on the drying stage of the encapsulation process. Its objective was to study the encapsulation of fish oil with soy proteins by emulsification and lyophilization and compare microparticles characteristics with those processed identically but spray dried. RESULTS: Microparticles with different protein/oil ratios were prepared by emulsification and lyophilization. Soy proteins encapsulated fish oil in matrix-type microcapsules masking its typical odor and oily appearance. Microparticles dried by lyophilization showed a better solid recovery but lower encapsulation efficiency than those spray dried. Increasing protein/oil mass ratio of initial formulations seemed to favor initial lipid oxidation, but these differences were not appreciated when analyzing the oxidative stability over time (measured by Rancimat test). Porous structure and large surface area of lyophilized samples would favor oxygen easy penetration and exposition to free radicals, increasing lipid oxidation over time, while spray dried microparticles showed a good oxidative stability over time, like that of free oil. CONCLUSION: Drying processes were determinants in the morphology of microcapsules, the efficiency of encapsulation and protection exerted on the oil. Although emulsifying and drying processes caused certain initial oil oxidation, soy proteins managed to mask fish oil flavors and spray dried systems showed a good perspective of oxidative stability of fish oil over time, better than that of lyophilized microparticles. © 2021 Society of Chemical Industry.

Synthesis and conservation of cellulose nanocrystals.

This work deals with the preparation of cellulose nanocrystals (CNC) from microcrystalline cellulose by acid hydrolysis, discusses how their characteristics varied according to the drying technique used for their conservation and analyzes their re-dispersion in water. A stable water dispersion of "rod" or "needle" type CNC (≈5 nm of diameter, 276 nm of length and 41 mV of Z potencial) was initially prepared and then dried by lyophilization and spray. Thus powders with similar cristalinity but different morphology were obtained, while CNC seemed to aggregate in such an extent that hindered their re-dispersion in water. Only lyophilized CNC could be re-dispersed in water and maintained stable in dispersion for at least 24 h, when working with concentrations of CNC higher than a certain minimum value (3 %) and after submitting them to intense ultrasound treatments. The tested time achieved should be enough to allow their subsequent use in several applications.