Development of Omega-3 Fish Oil Fortified Functional Stirred Yoghurt by Incorporating Annona muricata (Soursop)
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Date
2021
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Publisher
Uva Wellassa University of Sri Lanka
Abstract
Fish oil is an ideal source of Omega-3 polyunsaturated fatty acids (PUFAs) which lower the risk of
numerous non communicable diseases. Consumption of fish oil is not popular in Sri Lankan
community. This study aimed to develop a fish oil fortified functional stirred fruit yoghurt to deliver
Omega-3 PUFAs and to evaluate the effect of fortifying yoghurt with fish oil on sensory,
physicochemical properties and oxidative qualities. Initial sensory analysis for fish oil fortified
yoghurt was performed by adding 5% (w/w) three different fruit juices including soursop, mango and
pineapple by thirty untrained panelists. Fish oil fortified soursop added stirred yoghurt showed the
highest score for overall acceptability as 7.32 ± 0.85 (p < 0.05). Results of second sensory analysis
have shown that addition of soursop up to 15% (w/w) level was considerably masked the fishy odor
and flavor of fish oil (1% w/w) fortified yoghurt. Fish oil emulsion was prepared with guar gum,
gelatin and glycerol using Nano emulsion technique. Physicochemical and oxidative qualities were
compared among fish oil emulsion added soursop yoghurt (FOESY), fish oil fortified plain yoghurt
(FOPY) and bulk fish oil fortified soursop yoghurt (BFOSY) during the storage of 21 days at 4°C.
Peroxide values (PV) were analyzed to determine oxidative stability. Syneresis values increased in all
yoghurt samples during storage. The highest syneresis value of 45.18 ± 1.98 was recorded by FOPY
on day 14. BFOSY and FOESY showed significantly lower syneresis (p < 0.05). pH values gradually
decreased and titrable acidity values as lactic acid increased in all treatments during storage.The pH
values of both FOESY and BFOSY was 4.5± 0.01 at day 14. FOESY recorded the lowest (p < 0.05)
PV (4.64 ± 0.12 mEq O2 kg-1) at day 21 compared to BFOSY and FOPY. The Escherichia coli and
coliform counts were complied with the requirements of SLS but yeast and molds counts had
exceeded SLS limits after 14 days. This study demonstrated the potential of producing fish oil
emulsion fortified functional yoghurt with acceptable level of sensory characteristics,
physicochemical properties and oxidative stability by incorporating soursop juice.
Keywords: Omega-3; Fortification; Fish oil; Yoghurt; Soursop
Description
Keywords
Food Science, Food Science and Technology, Food Technology, Yoghurt, Animal Production, Fish Oil