Abstract:
Fish oil is the main commercial source of omega-3 fatty acids. Application of fish oil
in food formulations is limited due to its rapid oxidation and ensuing organoleptic
changes. Encapsulation of fish oil using emulsification technique and creating layers
around the lipid droplets using layer-by-layer (Lbl) electrostatic deposition
technique can effectively solve these problems. Chitosan, obtained by the Ndeacetylation of chitin, is a suitable bioencapsulation agent. In this study three
emulsions were prepared using high speed homogenization of fish oil extracted
from Indian oil sardine (Sardinella longiceps), sodium caseinate, chitosan extracted
from shrimp (Penaeus monodon) shell waste and pectin at pH 5. Sodium caseinate
was selected to stabilize the primary emulsion. In secondary and tertiary emulsions,
chitosan and pectin were evaluated as the secondary and tertiary layers for
emulsions. Zeta potential and particle size of emulsions and chitosan nanoparticles
were measured. Scanning electron microscopy (SEM) and Fourier-Transform
infrared spectroscopy (FTIR) were done for the emulsions and creaming stability
and peroxide value of emulsions were compared. Extracted chitosan was analyzed
for its physicochemical parameters. The results revealed a 20% chitosan yield with
3% of moisture, 4% of nitrogen, 52% of crystallinity index, 542% of water binding
capacity, 419% of fat binding capacity, 79% of degree of deacetylation and 95%
solubility of extracted chitosan. FTIR spectra confirmed the structure of chitosan
compared with commercial chitosan. Average particle size of three emulsions and
chitosan nanoparticles were 0.727, 1.230, 0.813 and 0.830 μm respectively. The zeta
potential of emulsions and chitosan nanoparticles were -13, -5.46, -29 and + 48 mV
respectively. SEM images revealed the structural arrangement of powdered
emulsion with a rough surface and pores on the walls of capsules. Bonds between
wall material of nanocapsules and functional groups were also confirmed by the
FTIR spectra. There was a significant difference (p<0.05) between the peroxide
value and creaming index of all three emulsions. This study revealed that threelayered fish oil droplets could be produced by Lbl deposition, incorporating
caseinate, chitosan and pectin with stability against particle aggregation, creaming
and oxidation. It can also be suggested that chemically extracted chitosan can be
used with protein to encapsulate and stabilize the fish oil.
