The New Zealand Institute for Plant & Food Research Limited
Purification of Alaskan walleye pollock (Theragra
chalcogramma) and New Zealand hoki (Macruronus
novaezelandiae) liver oil using short-path distillation
Prepared by:
Matt Miller and Alexandra C.M. Oliveira
The New Zealand Institute for Plant & Food Research Limited
Objectives
Investigate the applicability of short-path distillation to refine crude
pollock oils
Take 7-year-old rancid hoki oil and see if we can make it meet
GOED standard
In general, investigate the applicability of using short path distillation
on marine oils
Add value to respective fisheries
The New Zealand Institute for Plant & Food Research Limited
Pollock and Hoki oils
Pollock
Fishery ~ 1 M metric tonnes
Major products
Surimi, boneless skinless fillets
and roe
By-products
Small amount produced
Hoki (Blue grenadier)
Quota ~150,000 metric tonnes
Major products
Boneless skinless fillets, surimi,
and roe
By-products
Fish meal, fish oil, omega 3
concentrates, collagen
products
The New Zealand Institute for Plant & Food Research Limited
Fatty acid profiles of pollock and hoki oils
Fatty acid g/100 g Pollock1 Hoki2
SFA 20.0 23.6
18:1n-9 OA 16.8 22.2
20:1n-9 3.4 10.6
Total MUFA 39.6 51.0
20:5n-3 EPA 15.0 6.0
22:6n-3 DHA 5.0 12.4
Total n-3 28.3 23.3
20:4n-6 AA 5.0 0.4
Total PUFA 34.4 26.4
Lipid class g/100 g
TAG 99.8 97.1
PL 0.2 0.7
1Wu TH et al. (2009). JOACS 2Miller MR et al. (2011) JOACS
The New Zealand Institute for Plant & Food Research Limited
• Oxidation is a series of negative (chain) reactions that produce off-
flavours and smells in oils
• Polyunsaturated oils are prone to oxidation
• Double bonds are very reactive
• Primary oxidation products (peroxides, dienes, free fatty acids)
• Secondary products
(carbonyls,
aldehydes, trienes)
• Acid value – measures
formation of FFA
Oxidation of oils
The New Zealand Institute for Plant & Food Research Limited
GOED Monograph
Acid value. Maximum 3 mg KOH/g; AOCS Official Method Cd 3d-63
Peroxide value. Maximum 5 meq/kg; AOCS Official Method Cd 8-53
Anisidine value. Maximum 20; AOCS Official Method Cd 18-90
TOTOX. Maximum 26 (result of calculation, (2 x PV) + AV)
Plus PCBs, Dioxins, Furans and Dioxin-like PCBs, Heavy Metals
The New Zealand Institute for Plant & Food Research Limited
Traditional fish oil purification process
Crude oil
Bottling/
capsules and
storage
DegummingRemoves soluble & insoluble
impurities e.g. proteins,
phospholipids, trace metals
Washing oil with organic acid
& mild heat (e.g. citric acid)
NeutralizationRemove free fatty acids,
water sol material
Wash oil with caustic soda &
mild heat
Bleaching Removes pigments, trace
soaps, sulphur- and
carbonyl-containing
compounds & trace metals
Treat the oil with an
absorbent e.g. activated
earth/carbon, chitosan, etc.
DeodorizationRemoves “fishy” odour
(aldehydes and
ketones) –oxidation
products
Distillation
Winterisation Removes stearines,
waxes, low melting point
TAG
Short path
distillation
The New Zealand Institute for Plant & Food Research Limited
Short-path distillation
Pope - Wiped-film distillation
and evaporation process
• Short residence time of the
feed liquid
• Significantly lowered
temperature due to high
vacuum capability
The New Zealand Institute for Plant & Food Research Limited
0
2
4
6
8
10
12
Crude 190 200 210
me
q/k
g
Hoki oil
Pollock oil
Peroxide value
Temp (oC)
The New Zealand Institute for Plant & Food Research Limited
Anisidine value
0
5
10
15
20
25
30
Crude 190 200 210
An
isid
ine
va
lue
Hoki oil
Pollock oil
Temp (oC)
The New Zealand Institute for Plant & Food Research Limited
Acid value
0
2
4
6
8
10
12
14
16
Crude 190 200 210
mg
KO
H/g
Hoki oil
Pollock oil
Temp (oC)
The New Zealand Institute for Plant & Food Research Limited
Acid value
0
2
4
6
8
10
12
14
16
Crude 190 200 210
mg
KO
H/g
Hoki oil
Pollock oil
Temp (oC)
The New Zealand Institute for Plant & Food Research Limited
Results
Shows potential
Free fatty acids and primary and secondary products of lipid
oxidation were effectively removed from hoki and pollock oils with
SPD to meet GOED standards.
Short-path distillation refines and deodorizes fish oils in a chemical-
free single-step process.
Kodiak is a pretty amazing place.
The New Zealand Institute for Plant & Food Research Limited
www.plantandfood.co.nz
The New Zealand Institute for Plant & Food Research Limited
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