Palm Oil in Frying Comparison

A) Frying of potato chips in a blend of canola oil and palm olein:
changes in levels of individual fatty acids and tocols

Mohammed Al-Khusaibi, Michael H.Gordon, Julie A. Lovegrove & Keshavan Niranjan

Abstract: The changes occurring in the levels of nutritionally relevant oil components were assessed during repeated frying of potato chips in a blend of palm olein and canola oil (1:1 w⁄ w). The blend suffered minimal reductions in omega-3 and omega-6 polyunsaturated fatty acids. There was no significant difference between the fatty acid composition of the oil extracted from the product and that of the frying medium, in all three cases. The blend also contained a significant amount of tocols which add nutritional value to the oil. The concentration of the tocols was satisfactorily retained over the period of oil usage, in contrast to the significant loses observed in the case of the individual oils. The blend also performed well when assessed by changes in total polar compounds, free fatty acids, p-anisidine value. When fried in used oil, the product oil content increased progressively with oil usage time. This study shows that blended frying oils can combine good stability and nutritional quality.

Source : International Journal of Food Science and Technology,  47: 1701–1709, 2012

 

B) Performance of Palm Olein and Soybean Oil during the frying of French fries and its effect on the characteristics of the fried product
Laura Natalia Fernandez-Cedi, Blanca E. Enriquez-Fernandez, Liliana Alvarez De La Cadena Y Yanez and Maria Elena Sosa-Morales.
Abstract: Performance of soybean oil and palm olein during the deep-fat frying of 45 batches of frozen prefried french fries was studied. The peroxide index increased faster for the soybean oil, with a final value of 12 meq/kg. Free fatty acids increased with the number of fried batches and were higher in the palm olein. Total color change was more noticeable in soybean oil in comparison to the palm olein. Viscosity, total polar compounds, and p-anisidine values increased and were higher in soybean oil. A reduction of unsaturated fatty acids was observed from the chromatography analysis. Elaidic and linoelaidic acids, which are trans-fatty acids, had higher concentrations in degraded soybean oil. Palm olein was more stable than soybean oil under the conditions of this study and produced french fries with a lower oil content.

Source: Journal of Culinary Science & Technology, 10:211-222, 2012

Comments: The above are 2 recent studies, examining palm olein’s frying performence. Study A looked at the performence of palm olein/canola blend while study B compared the frying performence of palm olein and soybean oil.
Over the years, many frying studies comparing palm olein (liquid fraction of palm oil) with other types of edible oils has been undertaken to examine their stability at high frying temperature. In those studies, more often than not, palm olein surpassed the other edible oils in terms of its frying performance. Consistent with previous evaluations, study B, which compared the frying performance of palm olein against soybean oil showed very similar outcomes.  The key factor which is responsible for palm olein’s superior frying performance is its stability at high frying temperature. It does not easily breakdown and produce by products of oil deterioration.

No. of Cycle

Peroxide value (meq/kg oil)

p-Anisidine value

 

Soybean oil

Palm olein

Soybean oil

Palm olein

0

4.15 ± 0.37

2.56 ± 0.24

6.43 ± 1.78

2.75 ± 0.54

1

4.40 ± 0.20

4.28 ± 0.82

34.76 ± 1.82

13.30 ± 1.27

2

5.22 ± 1.57

4.42 ± 0.63

51.60 ± 1.01

30.11 ± 1.25

3

6.78 ± 1.41

4.03 ± 0.65

74.59 ± 3.31

40.83 ± 4.62

4

6.59 ± 0.03

4.51 ± 0.21

72.12 ± 10.50

42.62 ± 2.40

5

12.04 ± 0.55

4.01 ± 0.84

60.04 ± 1.75

46.54 ± 7.08

Table 1. Peroxide Index and p-Anisidine value of fresh oil and oil used after 5 frying cycles.
Courtesy of Laura Natalia Fernandez-Cedi et al. Journal of Culinary Science & Technology, 10:211-222, 2012

Stability of palm olein is well depicted in Table. 1, whereby its deterioration indicators, peroxide value and p-anisidine value throughout the 5 frying cycles remained practically constant. The stability of palm olein at high frying temperature is coupled with its high oxidative stability to further enhance its frying performence. These two factors are key attributes which makes palm olein the oil of choice among industrial fryers. Palm olein’s attractiveness among food manufacturers is further enhanced by its competitive princing which also contributes to its widespread use in global frying.

It does not stop there because if we look further at study B, in addition to its good frying performance, the results in study B show that the quality of fried products were not significantly compromised even after several frying cycles with palm olein. The same cannot be said about food fried in soybean oil.  One of the key quality aspects observed was oil absorbtion. In study B, the average oil absorbtion detected in the final products after 5 frying cycles in palm olein was less than 10% compared to about 15% for those fried in soybean oil. Lower oil absorbtion translates into good quality food products which are nutritionally better and are of higher sensory acceptance. This is well depicted in the result in Figure.1


                  Figure 1. Fat content in soybean oil and palm olein after 5 cycle.
Courtesy of Laura Natalia Fernandez-Cedi et al. Journal of Culinary Science & Technology, 10:211-222, 2012

Another important quality aspect which was closely monitored was the texture of the fried food products. It was observed that food fried for 5 frying cycles in palm olein produced a more consistent texture throughout compared to those fried in soybean oil. A good and consistent texture translates into good quality food products with good consistency of hardness and crispiness which affects its overall quality. This comparison is depicted in Figure. 2.

One of the many strengths of palm olein is it versatility for used in blends with other soft oils. Blending of palm olein is a common practice in many regions of the world including in places where soft oils are predominantly produced. It also makes a lot of economic sense, especially for industrial fryers because palm olein is more cost effective compared to other polynsaturated oils such as soybean, corn, sunflower among many others. Apart from its favourable cost factor, blending of soft oils with palm olein improves the stability of the blend and its overall performance. The result in study A concurs with this observation whereby fewer changes in the total polar compound, free fatty acids and p-anisidine value were detected after about 20 frying hours in the blend. Similarly, significant levels of tocols were detected after about the same frying duration. Hence, this study confirmed that in addition to improving the stability of the blend, the nutritional quality was preserved to a certain degree. 


Figure 2. Texture of Frech fries fried in soybean oil and palm olein after 5 cycle.
Courtesy of Laura Natalia Fernandez-Cedi et al. Journal of Culinary Science & Technology, 10:211-222, 2012

Based on our current knowledge, the strength of palm olein as frying oil lies in its stability at high temperature and also its high resistance against oxidative degradation. Foods which are fried in palm olein tend to have superior shelf life and this is one of the main reason it is the prefered choice in deep fried food industry. Palm olein has a balanced ratio of saturated and unsaturated fatty acids which is uncommon among edible oils. It also contains a significant level of the touted beneficial oleic acid. This balanced profile is what makes palm olein very versatile in its application and its composition contributed significantly toward its high temperature stability. Other postive frying attributes of palm olein include its bland neutral taste which carries the natural taste of the fried foods. Last but not least, palm olein would not need to be hydrogenated to impart stability, a process which generates the undesirable trans fatty acids.

 

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