comparison of the frying performance of market samples of palm

Pertanika 10(5), 295 - 304 (1987)

Comparison of the Frying Performance of Market Samples ofPalm Olein, Corn Oil and Soya Oil in Malaysia

M.A. AUGUSTIN \ K.H. LEE ] and K.T. YAU 2

department of Food Science,Faculty of Food Science and Biotechnology,

Universiti Pertanian Malaysia,43400 Serdang, Selangor Darul Ehsan, Malaysia.

2Palm Oil Research Institute of Malaysia,P.O. Box 10620, 50720 Kuala Lumpur, Malaysia.

Key words: Frying performance; palm olein; corn oil; soya oil.

ABSTRAK

Prestasi penggorengan 3 jenis minyak yang dipasarkan di Malaysia iaitu minyak kelapa sawitolein, minyak jagung dan minyak kacang soya, dibandingkan. Kajian ini melibatkan penggorengankepingan ubi kentang secara tidak berterusan untuk setiap Vzjam dalam masa 5 jam sehari selama 4hart berturut-turut. Penganalisisan minyak telah menunjukkan bahawa semasa proses penggorenganberlaku: (i) pengoksidaan asid lemak tak tepu seperti yang ditunjukkan oleh perubahan-perubahandalam nilai iodin dan komposisi asid lemak, kurang dalam minyak kelapa sawit olein berbandingdengan minyak jagung dan minyak soya, (it) pembentukan polimer kurang dalam minyak kelapasawit olein daripada minyak jagung dan soya, (Hi) kadar perubahan nilai asid adalah lebih tinggidalam minyak kelapa sawit olein dan (iv) selepas 4 hart minyak jagung mempunyai warna yang palingcerah.

ABSTRACT

The frying performance of market samples of palm olein, corn and soya oils sold in Malaysiawere compared. The oils were used for intermittent frying of potato slices at half hour intervals for aperiod of5hr per day for four consecutive days. Analyses of oils showed that during drying (i) the oxida-tion of unsaturated fatty acids, as shown by changes in iodine value and the fatty acid composition,was less in palm olein than in corn and soya oils, (ii) polymer formation was least in palm olein com-pared to corn and soya oils, (Hi) the rate of change in acid value was highest in palm olein and (iv) thatafter 4 days of frying, corn oil had the lightest colour.

INTRODUCTIONA major proportion of edible oils is used in deep-frying operations which is one of the most com-mon methods of food preparation. The fryingperformance and quality of the oil under fryingconditions are of interest to oil processors, com-mercial fry operators and individual consumers.During frying operations, oil is continuously orrepeatedly exposed to high temperatures in thepresence of air and moisture. Under these con-ditions, hydrolysis and both thermal and oxida-

tive decomposition take place. Degradation ofthe fat results in the formation of volatile andnon-volatile decomposition products. Amongsome of the physical and chemical changes thatoccur during frying are increased smoking,foaming, colour and viscosity and the formationof free fatty acids, hydroperoxides, carbonylsand other products of secondary oxidation andhigh molecular weight polymerized compounds.(Chang et at., 1978; Fritsch, 1981; Roth andRock, 1972). The overuse of frying oils affects

MA. AUGUSTIN, K.H. LEE AND K.T. YAU

the flavour, stability, colour and texture of friedfood. The nutritional value and safety of the oilcan also be affected (Alexander, 1978).

A number of frying oils, both locally pro-duced and imported, are available in the Malay-sian market. Palm olein, the liquid fraction ofpalm oil, is the major cooking oil producedlocally. Corn and soya oils are among two of themore popular types of imported frying oils in themarket. The prices of these oils in the localmarket vary, with the imported oils being moreexpensive than the locally produced palm olein.There has been no study on the performance oflocal market samples. It was thus of interest tocompare the quality of palm olein, soya and cornoils during frying. It should be noted that thisstudy was limited to the evaluation of marketsamples of frying oils available at local outletsonly.

MATERIALS AND METHODS

MaterialsRandom samples of refined, bleached anddeodorized palm olein, corn oil and soya oil werebought at the supermarket. The oils for eachbatch were bought about a week before the startof the frying experiment. The same brand foreach oil was used each time. Potatoes used infrying experiments were also from a local distri-butor and similar varieties could not be assuredfor each frying trial. Different varieties wereused for all three trials. The potatoes werebought a few days prior to each frying trial. Thepotatoes were peeled and sliced to a thickness of2mm using a mechanical slicer and slightlyblotted dry prior to frying.

Frying ExperimentsFryings were done in Valentine Fryers. Four kgoil was heated up to 180°C in 10 min and fryingswere started half hour after the temperature ofthe oil had reached l"80°C. One hundred gmpotato slices were fried for 3 minutes at 0.5hrintervals for 5hr per day for four consecutivedays. This is equivalent to 10 fryings a day. Thefryer was left uncovered during the fryingperiod. At the end of each day, lOOg oil wasremoved from the fryer and kept in a cold roomat 6°C until the day of analysis. The lid of the

fryer was then put on and the oil was allowed tocool overnight. The fryings were continued thenext day.

Analysis of OilsThe peroxide and p-anisidine values of the oilswere determined before the start of the experi-ment. Other analyses of oils were completedwithin three weeks after frying. The peroxideand iodine values were determined according toAOCS methods (AOCS, 1974). IUPAC methodswere used for the assessment of acid and/>-anisidine values (IUPAC, 1979). The fattyarid profile of the oil was determined by gaschromatography after preparation of methylesters (Christopherson et al., 1969; Timms,1978). The gas chromatograph was fitted with a10% SP 2330 column and a Flame IonizationDetector. The injector and detector tempera-tures were 250°C while the column temperaturewas 190°C. The flow rate of the carrier gas was40ml/min. The % polar components was deter-mined by column chromatography (Billek et al.,1978) while polymer content was determinedaccording to the method of Peled et al. (1975).The dielectric constant was measured on a FoodOil Sensor (NI-20, Northern Instruments). Theinstrument was calibrated with standardsprovided by the supplier. Colour was measuredin a 1" cell in a Lovibond Tintometer.

The initial oil was also screened for thepresence of the antioxidants BHA, BHT andTBHQ using high pressure liquid chromato-graphy. The method used for extraction anddetermination of antioxidants was based on thatby Kirleis and Stine (1978) and Page (1979).

RESULTS AND DISCUSSION

Characteristics of the Fresh OilsThe quality characteristics of the fresh oils aregiven in Table 1 while the fatty acid compositionof the oils are given in Table 2. The fatty acidcomposition of all samples of palm olein arewithin the range for Malaysian palm olein (Tanand Oh; 1981). The fatty acid composition of allsamples of corn and soya oil are within therespective ranges that were tentatively adoptedby the Food and -Agricultural Organization/World Health Organization Codex Alimentarius

296 PERTANIKA VOL. 10 NO. S, 1987

COMPARISON OF THE FRYING PERFORMANCE OF SAMPLES OF PALM OLEIN, CORN OIL & SOYA OIL

TABLE 1Quality characteristics of the fresh oib

Quality characteristic Batch Palm olein Corn oil Soya oil

Peroxide value (meq/kg)

p-anisidine value

Acid value (mg KOH/g)

123

123

123

1.530.831.48

1.71.91.6

0.180.150.20

3.653.553.74

6.66.87.6

0.170.160.16

11.8514.162.14

2.52.72.2

0.170.210.33

Each value in the table represents the mean value of duplicate analyses. The error in peroxide value, /> anisidine value and acidvalue were less thanO.25meq/kg, 0.5 and 0.02mg KOH/g oil and respectively.

TABLE 2Fatty acid composition of the oils

Type ofoil

Batch Days offrying

C16:0 C18:0 C18:l C18:2 C18:3 Others

Palm olein

Palm olein

Palm olein

Corn oil

Corn oil

Fresh oilDay 1Day 2Day3Day 4

Fresh oilDay 1Day 2DaySDay 4


Fresh oilDay 1Day 2DaySDay 4Fresh oil

Day 1Day 2DaySDay 4

39.9240.2941.1241.8442.72

40,0640.8041.5042.4443.09

39.2539.7740.2741.1241.50

11.8012.0512.1912.1512.7111.91

12.2912.5512.8713.23

4.224.334.314.354.44

4.284.384.474.544.57

3.984.104.184.134.27

1.952.022.042.072.112.00

2.122.102.182.26

43.9444.2844.0443.6843.27

43.7843.6943.7143.5043.16

44.7345.0745.2344.8044.74

29.1429.5929.9630.9830.7029.27

30.1030.5431.1531.73

10.669.879.218.698.14

10.709.949.078.247.92

10.719.738.968.548.13

57.1156.3455.8154.4454.4856.80

55.4854.8153.7952.76

1.261.231.321.441.43

1.181.191.251.281.26

1.331.S31.361.411.36

0.36

0.01

0.01

0.010.02

PERTANIKA VOL. 10 NO. 3, 1987 297


TABLE 2 (Cont.)Fatty acid composition of the oils

Type ofoil

Batch Days offrying

C16:0 C18:0 C18:l C18:2 C18:3 Others

Corn oil

Soya oil

Soya oil

Soya oil


Fresh oilDay 1Day 2Day 3Day 4


Fresh oilDay 1Day 2Day SDay 4

11.4211.7112.1712.4412.92

11.8011.9212.0112.2512.77

11.5811.9512.1912.3113.05

11.7712.4112.7013.0513.29

1.891.922.022.092.19

3.783.864.014.164.16

3.934.014.094.304.47

3.774.054.254.164.22

29.3930.5131.1931.6532.08

24.3023.9924.2825.0025.35

23.8424.2524.9025.2426,13

23.6624.6525.3025.1725.91

57.1755.7854.5553.7352.61

52.4252.5552.3451.2751.94

52.7452,2851.4351.1149.93

53.1851.7851.0550.9950.27

—--—-

7.457.447.157.075.53

7.667.247.136.776.13

7.456.956.516.446.10

0.130.080.070.090.20

0.250.240.210.250.25

0.250.270.260.270.29

0.170.160.190.190.21

Each value in the table represents the mean value of duplicate analyses. The mean differences in fatty acid composition induplicate analysis were less than 0.3%. It should be noted that the data gives the fatty acid composition of glyceride bound fattyacids as the method used for esterification only esterifies glyceride bound and not free acids,

" " indicates not detectable.

Committee for Fats and Oils (Spencer et ai,1976). The peroxide, p-anisidine and acid valuesof RBD olein were 0.83 - 1.53meq/kg, 1.6-1.9and 0.15-0.20mg KOH/g oil respectively. Thelow oxidation values and acid value of RBD oleinshowed that the oils were of good quality. Theacid value of corn oil was comparable to that ofpalm olein. The acid values of soya oil werebetween 0.17-0.33mg KOH/g oil. Theperoxide values of corn and soya oils were 3.55 —3.74meq/kg and 2 .14- 14.16meq/kg respec-tively while the corresponding ^-anisidine valueswere 6 .6-7 .6 and 2 .2-2 .7 . The results showedthat these market samples of corn and soya oilshad higher oxidation values than samples of thecommercial brand of palm olein used in theseexperiments. It should be noted that these cornand soya oils are imported into Malaysia whilepalm olein is produced locally. The higher oxida-

298 PERTANIKA

tion values of the corn and soya oils are probablythe result of the greater degree of handling, trans-portation and storage of these imported oilscompared to palm olein. Reference to work onoils carried out in the U.S. showed that peroxidevalue of commercial fresh soya and corn oilswere 1.3meq/kg and 0.46meq/kg respectively(Carlson and Tabacch, 1986). The results ofHPLC analyses showed that all samples of cornoil contained BHA while all samples of soya oilcontained TBHQ,. No antioxidants were foundin palm olein. A check with the company pro-ducing the brand of palm olein used in theseexperiments confirmed that no antioxidants hadbeen added to the oil.

Although the oxidation values of the freshoils were different and both corn and soya oilshad antioxidants while palm olein had no anti-oxidants , the experiments were nevertheless

VOL. 10 NO, 3, 1987


carried out as the study was aimed at evaluatingmarket samples of these oils available inMalaysia.

Quality Changes in Oils During FryingTable 2 gives the fatty acid composition of thefresh and used oils. The quality changes in palmolein, corn and soya oils used for frying are givenin Table 3.

Iodine Value and Fatty Acid Composition:The changes in iodine value of the three batchesof oil after four days of frying were 4.4 - 4.9 forpalm olein, 6.3 - 10.1 for corn oil and 7.1 - 10.8for soya oil. The smaller change in iodine valuein palm olein compared to that of corn and soyaoils indicated that less oxidation of unsaturatedfatty acids has taken place in palm olein. Thefatty acid composition of the oils before andafter frying (Table 2) also showed that lesseramounts of unsaturated fatty acids were oxidizedin palm olein than in corn and soya oils. Similar-ly, the smaller change in iodine value in batch 1of corn oil compared to the other two batchesalso reflects the lesser extent of oxidation ofC18:2 in this batch of corn oil. This trend wasalso evident in soya oil.

The changes in iodine value and the fattyacid composition showed that during frying,there was a similar degree of oxidation in soyaoils (Batches 2 and 3) although they had dif-ferent initial peroxide value of 14.16 and2.14meq/kg. In contrast, soya oils (Batches 1and 2) with more similar initial peroxide valuesof 11.85 and 14.16meq/kg had experienced dif-ferent rates of oil deterioration during frying.The p-anisidine values for all the soya oil sampleswere similar. It is interesting to note these pointsalthough the reasons for them are unclear. Dif-ferent rates of oil deterioration were also foundin corn oil (Batches 1 and 2) although the oxida-tion values of the initial oils were similar. Thedifferent rates of oxidation in oils with similarinitial oxidation values, was evidenced not onlyby the analyses of iodine values and fatty acidcomposition but also by the results of percen-tage polar components, polymer content anddielectric constant (Table 3).

Polar Components and Dielectric Constant:The percentage polar components in palm olein,corn oil and soya oil after four days of frying

PERTANIKA VOL.

were 2 7 . 2 - 2 7 . 7 % , 2 2 . 7 - 3 2 . 7 % and 2 6 . 5 -32.8% respectively. The corresponding averagechanges in percentage polar components were18.6%, 23.4% and 24.2% respectively. Theaverage changes in dielectric constant werebetween 2 . 6 5 - 2 . 8 5 for all the oils after fourdays of frying.

Billek et ai (1978) states that frying oil with27% or more polar components should be dis-carded. The results showed that most of the oilsamples had reached the end of their useful fry-ing life after four days of intermittent frying.

The dielectric constant has been used as aquick method for monitoring oil deterioration(Fritsch, 1979). However, Paradis and Nawar(1981) cautioned that the dielectric constantreading may not indicate the quality of the oil.Fresh fats differ in dielectric constant andartefacts present in the frying fat such as wateror fat extracted from the fried food can affectthe readings.

The correlations between % polar compo-nents and dielectric constant for each of the oilsused are given in Table 4. The results show thatthere are significant correlations between %polar components and dielectric constant foreach of the batches of the three types of oilsalthough the regression equations which describethis relationship are different.

Polymers: The results showed that therewas a higher percentage of polymers in corn andsoya oils than in palm olein after four days offrying (Table 3). No polymers were detected inany of the fresh samples of oil used. The forma-tion of polymers is believed to require the pre-sence of conjugated dienes (Kappelmeir, 1933).As evidenced by the changes in iodine value(Table 3), the more unsaturated oils, corn andsoya oils, experienced a faster rate of oxidationof unsaturated fatty acids than palm olein. Theconjugated dienes are the primary oxidationproducts of unsaturated fatty acids and thus itmay be expected that a higher rate of oxidationof fatty acids results in a faster rate of formationof polymers. Experiments on the frying per-formance of peanut oil, which is also more un-saturated than palm olein, also showed a fasterformation of polymers in peanut oil than in palmolein (Bracco etai, (1981).

Acid Value: The changes in acid value in

10 NO. 3, 1987 299

M.A. AUGUSTIN, K.H. LEE AND K.T. YAU

TABLE 3Quality characteristics of oils used for frying

Type ofoil

Day offrying Batch 1

Quality characteristicBatch 2 Batch 3

Palm olein

Corn oil

Soya oil

Palm olein

Corn oil

Soya oil

Palm oil

Corn oil

Soya oil

Palm olein

Fresh oilDay 4

Fresh oilDay 4

Fresh oilDay 4







Fresh oilDay 4

59.454.5

128.4122.1

137.1130.0

9.4613.8918.7325.0427.72

6.018.79

13.5618.9122.73

7.5710.3515.5020.4726.46

1.482.092.923.664.38

1.562.012.403.053.63

1.822.362.973.604.18

01.6

Iodine value

58.353.9

130.1120.7

136.5127.0

Polar components (%)

8.1912.4417.9223.0927.20

5.6814.1822.8327.33S2.74

7.5217.6024.1328.6832.78

Dielectric constant

1.171.912.703.324.04

1.632.443.364.124.29

1.882.803.564.005.20

Polymer content (%)

01.9

58.253.6

128.1118.0

141.5130.7

8.6513.1618.9524.8827.46

3.2914.2220.5727.7229.72

4.2116.5222.5729.5932.69

Not determined

Not determined

Not determined

01.1

300 PERTANIKA VOL. 10 NO. 5, 1987


TABLE 3 (Cont.)Quality characteristics of oils used for frying

Type ofoil

Corn oil

Soya oil

Palm olein

Corn oil

Soya oil

Palm olein

Corn oil

Soya oil

Day offrying

Fresh oilDay 4

Fresh oilDay 4






Day 1Day 2Day 3Day 4

Batch

01.7

02.5

0.180.390.691.061.40

0.170.260.350.460.63

0.170.540.791.011.20

1.8Y, 0.4R3.5Y, 0.6R4.0Y, 0.6R5.2Y, 0.6R6.6Y, 0.8R

1.2Y, 0.2R1.7Y, 4.3R2.4Y, 0.3R2.7Y, 0.4R4.1Y, 0.5R

0.4Y1.3Y2.7Y, 0.4R4.6Y, 0.6R

Quality characteristic1 Batch 2

Polymer content (%)

03.1

03.4

Acid value (mg KOH/g oil)

0.150.330.590.941.31

0.160.£70.440.640.87

0.210.410.620.841.11

Lovibond colour (1M cell)

1.7Y, 0.3R3.2Y, 0.4R3.6Y, 0.5R4.3Y, 0.5R5.9Y, 0.6R

1.2Y, 0.2R1.7Y, 0.3R3.0Y, 0.4Y4.0Y, 0.5R5.5Y, 0.7R

0.4Y1.3Y4.2Y, 0.5R6.4Y, 0.7R

Batch 3

02.9

02.7

0.200.470.791.091.49

0.160.240.380.560.78

0.330.530.690.881.07

1.8Y, 0.4R3.3Y, 0.5R3.6Y, 0.5R4.5Y, 0.6R6.3Y, 0.8R

1.2Y, 0.2R1.7Y, 0.3R2.4Y, 0.4R3.7Y, 0.5R4.4Y, 0.7R

0.4Y1.3Y3.8Y, 0.5R5.6Y, 0.7R

Each value represents the average of duplicate analyses. The average difference between the results of duplicate analyses were0.2 for iodine value, 0.16% for polymer content, 0.4% for percentage polar components and 0.02mg KOH/g oil for acid value.

palm olein after four days of frying were greaterthan that in soya and corn oils. Changes in acidvalue were least in corn oil during 4 days offrying (Table 3). It should be noted that the acid

value is a measure of the acidic components inthe oil. Increased acidity levels can be dqe to theformation of free fatty acids resulting fromhydrolysis of the fat as well as oxidative chain


MA. AUGUSTIN, K.H. LLE AND K.T. YAU

TABLE 4Correlations between % polar components and dielectric constant

Type of oil Batch Regression equation Correlation coefficient

Palm olein

Corn oil

Soya oil

12

12

12

y = 6.466x + 0.179y = 6.798x - 0.098

y = 8.371x - 7.178y m 9.432x - 9.327

y = 8.049x - 7.964y = 7.725x - 4.804

0.99***0.99***

0.99***0.99***

0.99**0.97**

H Five pairs of values were used for calculation of each regression equation. •• denotes significance at 0.01 level and *** denotessignificance at 0.001 level.

cleavage reactions (Sims and Stahl, 1970). Anincreased rate of formation of acids is undesir-able (Wurziger, 1972). Acidity is one of thefactors that contributes to increased smokingduring frying. Smoking is considered undesir-able.

Colour: The initial colour and changes inoil colour during frying are given in Table 3.The colour of fresh samples of palm olein weredarker than those of corn and soya oils. It shouldbe noted that palm olein did not contain anyadded phenolic antioxidants whereas corn oilhad BHA and soya oil had TBHQ. The oxida-tion of phenolic antioxidants in the presence ofheat and metals results in the formation of qui-noid compounds (Lundberg, 1961) which lead tocolour formation. Despite the absence of addedphenolic antioxidants, the colour of palm oleinafter hour days of frying was darkest comparedto corn and soya oils.

Overall Assessment of Frying Oils: Al-though only three market samples of each type ofoils were used, the results nevertheless showedthat (i) the rate of oxidation of unsaturated fattyacids, as shown by the changes in iodine valueand the fatty acid composition, was slower inpalm olein than in corn and soya oils and (ii)polymer formation was least in palm olein ascompared to corn and soya oils. It was alsoevident that the acid value of palm olein washigher than that of corn and soya oil. However,the analysis of percentage polar componentsshowed that generally all oils had reached theend of their useful frying life after four days offrying.

It should be borne in mind that all the para-meters used in this study are indicators of thestate of oil deteriorations. Although no one para-meter can judge frying life adequately in allsituations, the analyses of percentage polar com-ponents is considered to be one of the morereliable indicators of the state of oil deterioration(Fritsch, 1981). In 1973, The German Society forfat research proposed that "A used frying fat isdeteriorated if, without any doubt, colour andtaste are not acceptable; if, in case of a doubtfulsensory assessment, the concentration of petro-leum ether insoluble oxidized fatty acids is 0.7%or higher and if the smoke point is lower than170°C, the concentration of petroleum ether in-soluble oxidized fatty acids is 1.0% or higher"(Billek et aL, 1978). A value of 1.0% petroleumether insoluble oxidized fatty acids was found tocorrespond with 27% polar components (Billeket aL, 1978). Based on the results obtained forBatches 2 and 3 and the assumption that %polar components is the most reliable indicatorof frying fat deterioration, it can be seen thatpalm olein reached the end of its frying life after4 days of frying whereas corn and soya oils haddeteriorated beyond the acceptable limit of 27%polar components after 3 days of frying underthe conditions used. This represents at least a25% saving for palm olein if oil is discardedwhen it reaches the 27% polar components level.

It should be appreciated that in theseexperiments, the oil was not replenished. Incommercial frying operations, the oils is"topped-up" with fresh oil. In addition, the sur-face area to volume ratio of the oil has an effect

302 PERTANIKAVOL. 10 NO. S, 1987


on oil deterioration, with rates of deteriorationbeing faster at higher surface area to volumeratios. Thus it may be expected that the rate ofdeterioration of frying oil is different under theconditions of our study. Nevertheless, it gives anindication of the relative rates of deterioration ofthe oils.

In addition to the quantitative analyses ofthe oils, observations made during fryings show-ed that foam formation was more obvious incorn and soya oils than in palm olein. Stickyfilms, presumably polymers were also formed onthe walls of the fryers with soya and corn oils.Off-odours were very noticeable in soya oilsystems during heating up of the oils prior tofrying during the later days of frying. It was alsonoted that although the colour of palm olein wasdarkest compared to corn and soya oils, thecrisps fried in palm olein had a similar colour tothose fried in corn and soya oils.

CONCLUSIONThis study shows that the market samples ofpalm olein, corn and soya oils undergo differentrates of oil oxidation and hydrolysis. Judgementof frying oil quality based on the test for per-centage polar components shows that four daysof frying under the conditions of the experimentgenerally causes the oils to deteriorate to a pointbeyond the maximum tolerable limit for use.The disadvantages of palm olein as compared tocorn and soya oils are the higher acid value anddarker colour of the used oils, but its advantagesare the lower rate of oxidation of unsaturatedfatty acids and the lower rate of formation ofpolymers. From a user point of view, an addi-tional advantage of palm olein is the easiercleaning of fryers, as the sticky films formed onthe walls of fryers in corn and soya oil systems arehard to remove. Furtermore, palm olein has alesser tendency to foam than corn and soya oils.

It should be noted that in this study, thethree random samples of each type of oil wasbought at retail outlets. There was no controlover the initial characteristics of the oils and thepresence of antioxidants in the oils. Both cornand soya oils had the advantage of having anti-oxidants but the initial quality characteristics ofpalm olein were better than of corn and soyaoils. These factors may have an effect on the

rates of oil deterioration and thus the results ofthis study are only applicable to the local edibleoil scene.

ACKNOWLEDGEMENTSThe authors would like to thank the Palm OilResearch Institute of Malaysia for sponsoring theresearch. Thanks are also due to Prof. A.S.H.Ong for his helpful comments.

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(Received 1 June, 1987)

304 PERTANIKA VOL. 10 NO. 3, 1987

comparison of the frying performance of market samples of palm

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