Unilever Food Safety Assurance System for Refined Oil

7/22/2019 Unilever Food Safety Assurance System for Refined Oil

1/4

QUALIT SCURIT SANITAIRE

Unilever food safety assurance system for refined vegetable oils and fats

Gerrit VAN DUIJNGerrit DEN DEKKER

Unilever Supply Chain Technology Unit,

P.O. Box 114,

3130AC Vlaardingen,

The Netherlands

Abstract:The Unilever Food Safety Assurance system for refined oils and fats is based on risk assess-ments for the presence of contaminants or pesticide residues in crude oils, and refining process studies

to validate the removal of these components. Crude oil risk assessments were carried out by combiningsupply chain visits, and analyses of the contaminant and pesticide residue levels in a large number ofcrude oil samples. Contaminants like poly-aromatic hydrocarbons and hydrocarbons of mineral origin,

and pesticide residues can largely be removed by refining. For many years, this Food Safety AssuranceSystem has proven to be effective in controlling contaminant levels in refined vegetable oils and fats.

Key words:analysis, contaminants, vegetable oils, refining, Unilever

The oil refining process was introduced in1900, to improve the quality of oils and fatsfor application in margarine production, andas cooking oil. The process was optimized toreduce the natural taste and colour, and toremove most of the free fatty acids presentin the crude oil. It was discovered years laterthat under these optimized conditions, theprocess also reduces the levels of many ofthe contaminants like metals, poly-aromatichydrocarbons, and minor components likepesticide residues.Towardtheendofthetwentiethcentury,mostof the food companies started a Food SafetyAssurance System intended for the ingredientsused in their products. Unilever developed aspecific system for the supply chains of oilsand fats. This system included an assessmentforthepresenceofcontaminantsandpesticideresidues in crude oils and the validation of therefining process for the removal (reduction tobelow safe limit) of these components:the crude oil risk assessment combined visitsof all steps of the crude oil supply chains withanalyses of contaminants and pesticide resi-dues in crude oils. These analyses were doneon all crude oils bought by Unilever for own

or toll refining in North West Europe for aperiod of four years (01/200112/2004). Thecrude oil risk assessment resulted in a crude oilrisk matrix;oil containing a high level of a specific con-taminant or pesticide residue was refinedunder standard process conditions, and the re-moval was checked by analyzing the level ofthis contaminant or pesticide residue in therefined oil.

Crude oil risk assessment

Supply chain visits

IntheperiodfromJanuary2003untilJuly2007,the supply chains of five major oils used byUnileverwere inspected for chemicals use, dry-ing procedures, and housekeeping practices.The following supply chains were assessed:soybean oil from central Brazil and mid-westUSA;sunflower oil from South Africa and France;rapeseed oil from Germany;palm oil from Malaysia (Sabah and peninsu-

lar Malaysia) and Indonesia (Sumatra);coconut oil from the Philippines.Farmers, plantation companies, seed storagecompanies, oil mills, oil transportation, and oilstorage companies were visited, and their pro-cedures were examined using questionnaires.Special attention was paid to the followingcontaminants and chemicals:pesticides used during growth and cropprotection after harvesting;poly-Aromatic Hydrocarbon adsorptionfrom exhaust gases during drying;mineraloilfromleakingequipmentsortrans-port vehicles;residues from previous cargoes during trans-port and storage of crop or crude oil.The following qualitative observations weredone:

Pesticides in oil seeds (for more detailson pesticides see van Duijn (2008)Pesticides are not applied in the last two weeksbefore harvesting to limit the residue levels inthe seeds. Insecticides are sometimes used as

post harvest treatment to protect seeds duringtransport and storage. Carry over of insecti-cides from previously treated grains may occurin storage silos.

Pesticides in palm oilHerbicides are used to control weeds in the cir-cle under the oil palm tree. Contamination ofloose fruits by herbicides is minimized by directapplicationafterharvesting.Insectsareincreas-ingly controlled by biological pest control; inthis case, chemicals are only used to controlpest outbreaks. Palm fruits are not stored forlong, and therefore postharvest treatment is

not applied.Pesticides in palm kernel and coconutApplication of pesticides for these crops has notbeen observed.

Drying practicesWhen moisture is too high, oil seeds are driedto a specified water level. This drying can be indirect contact with exhaust gases. This hasbeen observed for soybeans in wood-firedpacked bed dryers and sunflower seeds indiesel-fired counter current dryers. Directdryers are not allowed to be used in Europeand the United States of America.

Drying is an essential operation in the coconutoil supply chain, it avoids Aflatoxin formationand it releases the copra (coconut meat) fromtheshell.Inthemethod,whichispredominant,halved coconuts are dried upside down on agrid of a bamboo over an open fire, burningthe coconut shells.Palm kernels are washed and dried after crack-ing in the palm oil mill. Most, but not all mills,dry in indirect dryers.

100 OCL VOL. 17 N 2 MARS-AVRIL 2010


2/4

Mineral oil leakagesSmall, but visible mineral oil leakages havebeen observed in palm oil mills and at oil seedreception areas. More and more oil mills usefood-grade lubricants and hydraulic oils whenthere is an unavoidable contamination risk.

Residues from previous cargoes:Measures were in place in all the visited loca-tionstoavoidcontaminationwithpreviouscar-goes.Croptransportfromfarmorplantationtooil mill was carried out in clean and inspectedconveyances.Crudeoilsweretransportedfromthe mill to the port or customer in dedicatedand sealed trucks (sealing of empty return tripswould further improve security), tank parkswereallfoodstuffdedicatedandoverseastrans-port was according to the previous cargoregulations of the European Union (EU) orFederation of Oils, Seeds and Fats Associations(FOSFA).

Crude oil analyses

The crude oils bought by Unilever for own or

tollrefininginNorthWestEuropeintheperiodfrom January 2001 until December 2004 wereanalyzed for pesticides, poly-aromatic hydro-carbons (Benz(a)Pyrene) and hydrocarbons(C10C24). In total, 1595 samples were ana-lyzed, which included crude rapeseed oil (566samples), crude sunflower oil (154 samples),water-degummed soybean oil (157 samples),crudepalmoil(318samples)crudepalmkerneloil (236 samples), and crude coconut oil (164samples). The samples were taken by an inde-pendentsuperintendentfromdifferentlevelsinthe ship tanks and were analyzed in an inde-pendent laboratory (Laboratory Dr. A Verweij,

Coolhaven 32, 3024 AC Rotterdam, TheNetherlands). The results were as follows:

PesticidesAll sampleswere analyzedfor24organochlorinepesticides, 28 organophosphorus pesticides,9 nitrogen-based pesticides and 4 pyrethroids.The palm oil samples were also analyzed for14 pesticides frequently used by palm planta-tions as reported during the supply chain visits.Only a limited selection of mainly organo-phosphorus insecticides was detectable incrude seed oils (soybean, sunflower andrapeseed oil).Figure 1gives an overview of themaximum pesticide levels found in rapeseed,sunflower and soybean oil.No pesticide residues were detected in crudepalm oil, palm kernel oil, and coconut oil.

Poly-Aromatic HydrocarbonsAll crude oil samples were analyzed for Benz(a)Pyrene(BaP)levels.TheBaPisgenerallyusedasa marker for the presence of Poly-AromaticHydrocarbons in crude and refined oils. TheEC regulation 1881/2006 (EC, 2006) limits

the BaP level in oils and fats intended for directhuman consumption or as ingredient in foodsat max. 2 ppb.For the analyses, a sample with a BaP levelabove 1 ppb was considered to be contami-nated. The fraction of contaminated samples

was very high for crude coconut oil (79%),high for crude sunflower oil (12%) and below10% for crude rapeseed oil (9%), water de-gummed soybean oil (7%), and crude palmkernel oil (6%). None of the palm oil sampleshad a BaP level above 1 ppb. Figure 2gives an

1

10

100

1000

10000

Fenit

rothion

Mala

thion

Chlorpy

ripho

s-meth

yl

Pirim

iphos

-meth

yl

Parath

ion-meth

yl

Dichlor

vos

Chlor

pyripho

s

Endo

sulfa

ntotal

Max.

level(ppb)

Detection limitSoybean oilRapeseed oilSunflower oil

Figure 1. Results of pesticide residue analyses in crude seed oils. This graph shows the detection limit and themaximum observed levels for water-degummed soybean oil, crude rapeseed oil and crude sunflower oil.

0

10

20

30

40

50

60

70

80

Coconu

toil

Sunfl

ower

oil

Rape

seed

oil

Palm

kerneloil

Soyb

eano

il

Palm

oil

Oil type

BaP(ug/kg)

Average BaP in samples with BaP > 1 Max BaP

Figure 2. Results of BaP (Benz(a)Pyrene) analyses in crude oils. This graph shows the average of the samplescontaining more than 1 ppb BaP and the maximum observed levels.

OCLVOL. 17 N 2 MARS-AVRIL 2010 101


3/4

overview of the average and maximum BaP le-vels found in the crude oil samples with a BaPlevel higher than 1 ppb. This shows that all oilsexcept palm oil may occasionally have a BaPlevel before refining, which is higher than theEU limit of 2 ppb.

HydrocarbonsHydrocarbons in Mineral oil can be roughly di-vided in four fractions, depending on the car-bon numbers:gasoline (C5C10), purified hexane (C6) isused as a solvent in oil extraction and theresidue level in crude oils is restricted in thecontracts by the flashpoint (< 121 C);kerosene and diesel (C10C24);fuel and lubricant oil (> C16);asphalt (> C35).All tested crude oils were analyzed for keroseneand diesel contamination (C10C24), sincethese components were observed to be at ahigh level in crude palm oil in 1999. Detectablelevels of these hydrocarbons were only found incrude palm oil.Figure 3shows the average andmaximum observed levels of hydrocarbons in

the range C10C24 for the years 2001 until2004. Palm oil also contains natural hydrocar-bons in the range of C10C25; it is not clear sofar as to the level of natural hydrocarbons. In2007, the tri-partnership project of theMalaysian, Indonesian, and Dutch governmentagreed a maximum level of 25 ppm for C10C24 hydrocarbons in crude palm oil.

Other contaminantsThe levels of other contaminants like dioxins,PCBs and heavy metals (lead) were monitoredin some crude oil and refined oil samples. Thelevels in none of these samples were above

the limits set in EC regulation 1881/2006.

Crude oil risk matrix

The risk assessment for the presence of a spe-cific contaminant or pesticide residue in crudeoil is a combination of the observations madeduring the supply chain visits and the resultsofthe crude oil analyses. The identified risks areused to establish a crude oil risk matrix. Thismatrix shows the risk classification (high, me-dium, low) for presence of a contaminant orpesticide residue in a crude oil, in case the ori-gin of the crude oil is unknown (table 1). The

justification of this classification is:

PesticidesIn total, eight different organophosphorus in-secticides were found at detectable levels inseed oils. Crude sunflower oil had the highestmaximumobservedlevels(6insecticidesabove100 ppb of which 1 was higher than1000 ppb), crude rapeseed followed (3 insecti-cides above 100 ppb), while for soybean oil,

only the maximum observed level forEndosulfan was above 100 ppb. Pesticideswere not found in the tropical oils (palm,palm kernel, and coconut oil).

Benz(a)PyreneThe occurrence and maximum level of BaP incoconut oil were very high: occurrence 79%,maximum level 73 ppb. Sunflower oil had alowermaximumlevel(43ppb)andoccurrence(12%). The maximum levels for rapeseed,palm kernel, and soybean oil were between 2(EC-regulated level) and 10 ppb while theoccurrence was below 10%. No detectablelevel of BaP in palm oil has been observed.

Hydrocarbons of mineral oil originIncidents with high levels of hydrocarbons inedible oils have occurred for palm oil (diesel

contamination) and sunflower oil (grease oilcontamination in 2008). In both the cases,the origins of contamination were neverpublished. The customer cannot be sure if thecauses for contamination have been elimi-nated, therefore the risk of classification re-mains high. Palm kernel and coconut oil mayoriginatefromthesameregionsasthecontam-

inatedpalmoil,andarethereforeconsideredasmedium risk products.

Other contaminantsRisks here are classified as low, since; so far, alldetected levels are below the EC-regulatedlimits.

Risk matrix based analysesThe risk matrix can be used to determine thefrequency of the contaminant or pesticide resi-

0.0

5.0

10.0

15.0

20.0

25.0

30.0

35.0

40.0

45.0

50.0

2001Year

Hydrocarb

ons(ppm)

Average

Max

Crude palm oil

2002 2003 2004

Figure 3. Results of hydrocarbon analyses in crude palm oil. Analyzed were hydrocarbons in the carbon rangeC10C24. The graph shows per year the average for all samples and the maximum observed level.

Table 1.The crude oil risk matrix. This matrix shows the risk that a specific contaminant or pesticide residue is pres-ent in a crude oil of unknown origin.

Pesticides PAH Mineral oil in edible

oil imported in EU

Dioxins and

PCBs

Heavy metals

(lead)

LIMIT MRL BaP < 2 ppb Fediol CoP EC/1881/2006 EC/1881/2006

Soybean oil Medium Medium Low Low Low

Sunflower oil High High High Low Low

Rapeseed oil Medium Medium Low Low Low

Palm oil Low Low High Low LowPalm kernel oil Low Medium Medium Low Low

Coconut oil Low Very high Medium Low Low

102 OCL VOL. 17 N 2 MARS-AVRIL 2010


4/4

due analyses in crude oils from an unknownorigin. The proposed frequency is: very high and high risk check everydelivery;medium risk quarterly monitoring;low risk annual monitoring

Process validationcontaminant or pesticide

residue removalThe following procedure was applied to allcrude oils delivered to Unilever, for own or tollrefining, with a contaminant or pesticide resi-due level above detection limit (for hydrocar-bons and pesticides) or EC-regulated limit(for BaP):the refinery was informed of the contamina-

tion of the oil, and the contaminated lot wasblocked;

the refining process was validated forremoval of the contaminant or residue levelto below detection limit (for hydrocarbonsor pesticides) or EC-regulated limit (for

BaP). This process validation was done byprocessing a minimum batch with thestandard Unilever recipe for neutralization,bleaching (with active coal for Poly-Aromatic Hydrocarbon removal), and de-odorization and analyzing the contaminantor pesticide level in the processed oil;

the crude oil was de-blocked and the wholelot was processed when the level of testeddeodorized oil was below the limit;

this process was repeated for every deliveryof crude oil with a contaminant or pesticidelevel higher than the levels of the oils used inprevious process validations.

Pesticides

All pesticides found in the analytical surveywere extensively removed to below detectionlimit under the standard Unilever process con-ditions (neutralization, bleaching and deodor-ization at T > 230 C). Some of the pesticideswere already removed during neutralization(e.g., Dichlorvos), others during bleaching

(e.g.,Pirimiphos-methyl),butallwereremovedduringdeodorizationbecauseoftheirvolatility.The process conditions of the European refin-ing industry are not so different from the con-ditions applied by Unilever. Therefore, most ofthe industrial refineries will reduce organo-phosphorus pesticides to a level well belowthe level in the crude oil. However, for eachrefinery, a process validation is required forpesticide removal.

Poly-Aromatic Hydrocarbons

Heavy Poly-Aromatic Hydrocarbons (5 rings ormore) are removed by active carbon adsorp-tion, while light Poly-Aromatic Hydrocarbonsarealsoremovedbystrippingathightempera-ture deodorization (200-240 C). The BaP is aheavy Poly-Aromatic Hydrocarbon and needsactive carbon treatment for removal.The Unilever process validation experienceshows the following active carbon levelsneeded to reduce BaP to below 1 ppb:Coconut oil: 0.19% carbon for every 10 ppb

BaP in crude oil.Sunflower and rapeseed oil: 0.17% carbon forevery 10 ppb BaP in crude oil.A higher active carbon dosage is needed atlowerdeodorizationtemperatures.Theselevelsarerelativelyconservativeandresultinareduc-tion to a level well-below EC-regulated limit.

Hydrocarbons of mineral origin

Process validations were carried out with oilscontaining less than 25 ppm hydrocarbonsin the range C10C24. High temperaturedeodorization (T > 230 C) reduced these

hydrocarbons to below detection limit. Thereduction of hydrocarbons in the range C20C35 was less successful; the volatility of thisrange is apparently insufficient.

ConclusionsThe findings of the risk assessment visits cor-

related very well with the results of the crudeoil analyses.

The pesticides found in crude seed oilsare mainly organophosphorus insecticidesused to protect oil seeds during storageand transport after harvesting. No pesticideswere found in crude palm oil, crudepalm kernel oil, and crude coconut oil.Organophosphorus insecticides were exten-sively removed during refining.

Poly-Aromatic Hydrocarbons in crude oilsoriginate by absorption from exhaust gases

when these are used for direct drying of theoil crop. High levels were found in crude co-conut oil since direct drying is a commonpractice in the coconut oil supply chain.High levels may also occur in crude sunfloweroil, while in most other crude oils occasionalcontaminations may occur. Palm fruits arenever dried and Poly-Aromatic Hydrocarboncontamination has not been observedin crude palm oil. Heavy Poly-AromaticHydrocarbonsareremovedbyactivecarbontreatment, while light components willalso be reduced by high temperaturedeodorization.

Hydrocarbons in the diesel oil range (C10C24) in crude palm oil reducedover the test-ing period from max. 45 ppm and average10ppmtomax.21ppmandaverage8ppm.Partsofthesehydrocarbonsareofnaturalor-igin. High temperature deodorization(T > 230 C) reduced these hydrocarbons tobelow detection limit.

The effectiveness of the Food SafetyAssurance System for vegetable oils and fatswas confirmed by monitoring of deliveries ofindustrially refined oils to the Unileverproduct manufacturing sites.

REFERENCES

Van Duijn G. Industrial experiences with pesticide re-moval during edible oil refining.Eur J Lipid Sci Technol2008; 110: 982-9.

EC commission regulation N1881. SettingMaximum levels for certain contaminants in food-stuffs. Official Journal of the European Union:L364/5-24, 2006.

OCLVOL. 17 N 2 MARS-AVRIL 2010 103

Documents

Unilever Food Safety Assurance System for Refined Oil