Processing of marine oils - from catch to final product

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Temadag: Marine lipider – fra fisk til færdigvare, 25.juni, Aarhus

Research Manager Ana Carvajal, PhD

SINTEF Fisheries and Aquaculture

Processing of marine oils

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The fish oil and fish meal market

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Marine sources for oil production

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Processing of marine oils

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Production

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Refining

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Improve utization of available raw material

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A case from Norway

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Value chain marine oils

Crude oil Crude oil

Refined oil Refined oil

Cut-offs from salmon, cod liver or fish from Norway

Fish rich in omega-3 acids from South America or Morocco

Bottling or encapsulation _{Bottling or encapsulation}

Concentrating

Bottling or encapsulation FRESH RAW MATERIAL

FROM NORWAY CRUDE OIL IMPORTED _{TO NORWAY}

CONCENTRATED FISH OIL PRODUCED IN NORWAY OR ELSEWHERE

Refined oil containing 15–

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Can be divided in four categories

• Fish caught for fish meal/fish oil production

• Fish by-products/rest raw material from the processing industry

• Cod liver (from Gadus morhua L. or other gadidae species)

• Other marine resources (seal, krill, etc.)

Marine sources for production of oils

Peruvian anchoveta

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Production of marine oils

Traditional fish oil and meal production (wet-rendering method)

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Raw material quality

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Oil quality depend on the sorting, storage and

handling of the raw material

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Marine by-products (cut-offs) are especially

vulnerable for spoilage and degradation

– Blood and viscera, high amount of endogenous enzymes

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Lipases and phospholipases will lead to the

formation of free fatty acids – decrease oil

quality

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Lipid oxidation promoted by hemoglobin

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Microbial spoilage

Peruvian anchoveta

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Cooking

• Minced fish or by-products are transferred to a continous cooker, steam heated to 90 – 95 °C for aprox. 10 – 20 min

• Cooker:

– Long, steam-jacket cylinder, raw material is moved by a heated rotary screw conveyer (20 min procedure) – Scraped surface heat exchanger (less

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Pressing

• Heated material is transferred to a screw press

• The liquid ('press liqour') is squeezed from the solid phase ('press cake'), remove as much liquor as possible

• Optimal pressing: higher oil yield and a fish meal with low oil content

• Press liquid: water, dissolved materials and oil

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Separation of press liquor

• Press liquor passed over a vibrating screen (5-6 mm perforation) to

remove unwanted particles and bones

• Separation of the different phases (oil, water and remaining solids) based on their spesific gravitation

1. Decanter (horizontal centrifuge) – remove fine suspended solids from the liquor

2. Centrifuge – oil and water phase is separated into oil and stick water (water soluble components)

3. Polishing centrifuge –oil

Evaporator –stick water

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Oil polishing

• Remove final traces of moisture and impurities in the oil

• Reduces amount of pro-oxidants

present in the oil -> increased stability

• Oil pumped into storage tanks

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Drying of press cake – fish meal

• Sludge from the press liquor, press cake and concentrated stick water is mixed together

• Press cake is dried to reduce the moisture content

• Possible to use two different types of dryers: direct and in-direct

• In-direct dryers is used in the Norwegian fish oil and fish meal industry

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Enzymatic protein hydrolysis

• Based on the use of commercial proteases for proteolytical clevage of peptide bonds,

facilitating the degradation of the fish tissue and the release of oil

• Lower cooking temperature (50 – 60 °C)

compared to the traditional fish oil and meal process (90 – 95 °C), can give an oil of higher quality and stability

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• A hydrolysis stage is implemented after the material is minced

• The reaction can take place in either a reactor or a screw-mixing pipe reactor

• Raw material (whole fish or cut-offs) is transferred to the tank and mixed with water (1:1) and enzyme (0.1 – 1.0 % of raw material weight)

• Hydrolysis time: 30 – 90 minutes

• Enzyme inactivation at 90 °C for several minutes (usually > 85 °C for 10 min)

• Separation into 3 phases: oil, fish protein hydrolysate (FPH) and

sediments/sludge

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• Several commercial enzymes (proteases) are available for enzymatic protein hydrolysis of fish and fish by-products

• Endoproteases

• Attacks the proteins and peptides within the molecule by cleavage of internal bonds within the polypeptide chain

• Smaller peptides, low degree of free amino acids

• Alcalase (Novozyme), Protamex (Novozyme) and Papain (Enzybel)

• Exoproteases

• Attacks only near the end of the polypetide

• Flavourzyme (Novozyme)

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• Several factors can influence the hydrolysis process

• Substrate type and properties

• Enzyme type and properties

• Processing conditions

• Hydrolysis temperature

• Hydrolysis time

• pH

• Amount of water added

• Amount of enzyme added

• These factors are important for the yield and quality of the product and need to be controlled during processing

Enzymatic hydrolysis – process

parameters

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• Crude fish oils contains minor amount of water and unwanted substances

• Needs to go through refining before it can be used for human

consumption

• The refining process can include the following steps:

- Neutralisation

- Washing

- Bleaching

- Winterisation

- Deodorisation

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• Removal of free fatty acids and water soluble compounds

Process

• Oil heated to 80 – 90 °C

• Mixed with aqueous sodium hydroxide (NaOH)

• Settling, followed by discharge of soap fraction

• Mixed with water

• Water discharge

• Drying

Neutralisation/De-acidification

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• Removal of pigments, secondary oxidation products, vitamins, environmental pollutants, other polar components

Process

• Heating to 70 – 80 °C

• Drying to a water content < 0.2 %

• Addition of bleaching earth (synthetic bleaching earths, active carbon or silicates)

• Stirring at 80 – 110 °C for 30 – 60 minutes

• Filtration

• Polishing

Bleaching

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• Removal of volatile components, secondary oxidation products and persistent organic pollutants

Process

• Steam distillation

• High temperatures – up to 250 °C

• Low pressures – 3 – 8 mbar

• Batch or continuous

Deodorisation

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• The chemical composition and quality of the crude oils depend on both the production process and quality of the raw material

• Composition and quality of the oil will influence their edible properties and technical use

• No standard quality criteria are set for the crude oils. However, the quality of the crude oil will decide the range of application for the oil and how extensive refining is required

Quality criteria for marine oils for human consumption

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• Recommendation criteria's for refined oils are available based on the peroxide value (primary oxidation products) and anisidine value (secondary oxidation products)

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Need for new omega-3 sources and more valuable

utilization of the raw material

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• Defined a products that are not regarded as ordinary saleable products, but can be sold after further treatment*

• Estimated to make up around 75 % of the total catch**

• Contain valuable lipid and protein fractions, in addition to other components as nucleic acids, calcium and phosphorus

• Ingredients for human consumption if treated correctly

Marine by-products

*Rustad et al., 2011 **Torres et al., 2007

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In 2012, 229 000 T of by-products were generated from the Norwegian

herring and mackerel industry

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As much as 98 % of the herring by-products are currently being used

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But…

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they are mainly used for production of silage (preservation with formic

acid) or ordinary fish oil and fish meal for animal and fish feed.

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Filleting factories receive herring of food grade quality

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By treating the by-products in the same way, they can be used to make

products for human consumption

Herring by-products– a source of omega-3

and protein for human consumption?

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Herring by-products

229 000 T

29 770 T lipids

3 900 T n-3 lipids

~ 43 million people could get their daily recommended intake (250 mg (EFSA)) for a whole year around

~ 2.35 mill people could get their daily recommended intake for a whole year

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Crude oil (thermal treatment) Crude oil (enzymatic hydrolysis) Commercial crude oils* Silage GOED (refined oils) FFA 0.2 % 0.4 % 1 – 7 8 -10 PV 1.9 ± 0.3 2.5 ± 0.4 3 – 20 5 AV 0.7 ± 0.2 1.1 ± 0.1 4 – 60 20 TOTOX 4.5 6.1 10 – 60 20 – 25 30

High quality herring oil from fresh by-products

FFA – free fatty acids, % GOED – Global Organization for EPA and DHA PV – peroxide value, meq peroxide/kg oil

AV- anisidin value * In Long chain omega-3 oils, H, Breivik,2007 Totox = PV x 2 + AV

**salmon oil, earlier studies OSI was measured at 70⁰C

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• Has a lower content of EPA and DHA

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• Fresh raw material -> High quality oil and protein

• Reduced transportation and storage period

• Possible to trace the product through the whole value chain

• Additional source of lipids and proteins

Oils from fresh by-products versus imported South

American crude oil

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Thank you for your attention!

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