Properties of Fats and Oils

Table of Contents

Introduction

Ingredients constituting the diet regimen play essential role in enhancing the delicacy and nutrient value of a given food item. These may vary from naturally available plant or animal sources to chemically synthesized ones. The preparation of certain food items necessitates the utility of specific compounds such as oils and fats. These compounds are well known for their remarkable frying properties. It was reported that deep-fat frying induces the production of relevant or irrelevant flavor compounds that ensure flavor stability and quality of the oil by hydrolysis, oxidation, and polymerization (Choe and Min, 2007).

In addition, this property also facilitates the degradation of tocopherols, essential amino acids, and fatty acids in foods (Choe and Min, 2007).The oxidative stability and flavor quality of oils are lessened by the high frying temperature, the number of fryings, the contents of free fatty acids, polyvalent metals, and unsaturated fatty acids of oil (Choe and Min, 2007). The main reaction factors that accompany a frying process are replenishment of fresh oil, frying conditions, original quality of frying oil, food materials, type of fryer, antioxidants, and oxygen concentration (Choe and Min, 2007).

As oil enriched foods are subjected to storage, there is a high chance of the food item getting rancid, the property induced by the oil. Rancidity reactions are commonly encountered in oil or fat preparations (Naohiro Gotoh and Shun Wada, 2006).

But, this property is better determined by the Peroxide value. It is generally used as a measurement of the degree to which rancidity reactions have occurred during storage conditions (Naohiro Gotoh and Shun Wada, 2006). Here, the double bonds present in fats and oils play vital role in autoxidation. Oils with a high degree of unsaturation are most susceptible to autoxidation, a process that generates off- flavors and off-odours (Naohiro Gotoh and Shun Wada, 2006).

The best test for autoxidation (oxidative rancidity) is determination of the peroxide value. Peroxides serve as intermediates in the autoxidation reaction (Naohiro Gotoh and Shun Wada,2006)The delicious items that are most commonly cooked or fried are chips. These are fat rich products that are reported to cause fat-related diseases in individuals with a high fat intake. As such several attempts have been made to produce low fat and high quality chips through frying. It was reported that frying medium with minimum saturated and trans-fatty acid content is conducive for frying (Mehta & Swinburn, 2001).The beneficial effects of such a strategy are to regulate the blood lipids (Mehta & Swinburn, 2001).

To this end, there are various oils whose fatty acid composition could play important role in determining the organoleptic properties of chips. The fatty acids may be butyric, caproic, caprylic, capric, lauric, palmitic.oleic, stearic, linoeic, linolenic, arachidic, behenic, saturated and unsaturated ((www.journeytoforever.org). The profiles of these fatty acids may vary in oils like Lard, sunflower and olive oil. For example, the percentage of palmitic acid is 27.9 % in Lard, 6.5 % in sunflower and 11% in olive oil(www.journeytoforever.org). Therefore this study aims at assessing the quality of the oils with regard to their percentage of fatty acids, peroxide levels, observe the organoleptic properties of chips with reference t the differences in new and old fats.

Method

The methodology involves the chemical measures of deterioration where the free fatty acid and peroxide value of each fatty acid are determined before and after frying. This is in accordance with that reported in the manual (described by Williams, 1984) on the test to measure the quality or freshness of fat or oil.

Results

A total of three oils namely Lard, Sunflower and Olive oil were used in both old and new brand combinations. Lard (new) has imparted white color, opaqueness, no order at solid state. Lard (old) has imparted dark white color, opaqueness, rancidity at solid state. Sunflower (New) has imparted light yellow color, clearness with no odor at liquid state. Sunflower (old) has imparted light yellow color, unclear appearance, rancidity at liquid state. Olive oil (new) has imparted yellow color, clear appearance, non-rancid reaction at liquid state. Olive oil (old) has imparted much darker yellow color with non clear appearance and rancidity at liquid state.

Next, the percentages of free fatty acid content and peroxide value of new and old samples of Lard, Sunflower seed oil and olive oil are depicted in the table 3. The free fatty acid titrated values are – Lard (new) has 8 ml and 4 ml in sample and duplicate, respectively. Lard (old) has 8.7 ml and 9.5 ml in sample and duplicate, respectively. Sunflower seed oil (new) has 0.5 ml and 0.4 ml in sample and duplicate, respectively. Sunflower seed oil (old) has 1.2 ml and 1.0 ml in sample and duplicate, respectively. Similarly, olive oil (new) has 4.3 ml and 3.5 ml in sample and duplicate, respectively. Olive oil (old) has 5.7 ml and 5 ml respectively.

The results obtained on Monday class are as follows: For the sample and duplicate, the titrated free fatty acid values are: Lard new has 8 ml and 4 ml, and Lard old has 8.7 ml and 9.5 ml, respectively. Sunflower new has 0.5 ml and 0.4 ml, and Sunflower old has 1.2 ml and 1 ml, respectively. Olive oil new has 4.3 ml and 3.5 ml, and Olive oil old has 5.7 ml and 5 ml, respectively.

The average free fatty acid values are Lard (new) and old have 0.35 % and 0.53 %, respectively. Sunflower seed oil new and old has 0.02 % and 0.64 %, respectively. Olive oil (new) has 0.22 % and 0.3 %, respectively. The titrated peroxide values are as follows: Lard new has 0.1ml and 0.2 ml, and Lard old has 0.4ml and 0.4 ml, respectively.

Sunflower seed oil has 0.2 ml and 0.1 ml, and Sunflower old has 1.4 ml and 1.5 ml respectively. Olive oil new has 10 ml and 0.5 ml, and Olive oil old has 2 ml and 1.7 ml, respectively. The average peroxide values are as follows: Lard new has 3 and old has 8. Sunflower seed oil new has 2 and old has 29.Olive oil new has105 and old has 37.

For the Thursday class are the results obtained on Monday class are as follows: For the sample and duplicate, the titrated free fatty acid values are: Lard new has 9.7 ml and 11.9 ml, and Lard old has 5.6 ml and 9 ml, respectively. Sunflower new has 0.9 ml and 0.5 ml, and Sunflower old has 1.6 ml and 1.7 ml, respectively. Olive oil new has 3.5 ml and 2.9 ml, and Olive oil old has 5.4 ml and 5.9 ml, respectively.

The average free fatty acid values are Lard (new) and old have 0.7 % and 0.4%, respectively. Sunflower seed oil new and old has 0.03 % and 0.09 %, respectively. Olive oil (new) has 0.2 % and 0.3 %, respectively. The titrated peroxide values are as follows: Lard new has 1.5 ml and 1.5 ml, and Lard old has 0.5 ml and 0.4 ml, respectively.

Sunflower seed oil has 1.9 ml and 1.6 ml, and Sunflower old has 0.6 ml and 0.7 ml respectively. Olive oil new has 0.6 ml and 0.5 ml, and Olive oil old has 0.6 ml and 1.1 ml, respectively. The average peroxide values are as follows: Lard new has 30 and old has 9. Sunflower seed oil new has 35 and old has 13.Olive oil new has11 and old has 22.

The results obtained on Friday (AM) are as follows: For the sample and duplicate, the titrated free fatty acid values are: Lard new has 1 ml and 3.7 ml, and Lard old has 12 ml and 14.7 ml, respectively. Sunflower new has 0.5 ml and 0.5 ml, and Sunflower old has 0.5 ml and 0.7 ml, respectively. Olive oil new has 1.1 ml and 1 ml, and Olive oil old has 0.5 ml and 0.5 ml, respectively. The average free fatty acid values are Lard (new) and old have 0.14 % and 0.8%, respectively. Sunflower seed oil new and old has 0.03 % and 0.04 %, respectively. Olive oil (new) has 0.062 % and 0.03 %, respectively.

The titrated peroxide values are as follows: Lard new has 0.2ml and 0.2 ml, and Lard old has 1.4ml and 1.2 ml, respectively. Sunflower seed oil has 3 ml and 3 ml, and Sunflower old has 1.5 ml and 1 ml respectively. Olive oil new has 1.1 ml and 1.1 ml, and Olive oil old has 1.7 ml and 1.7 ml, respectively. The average peroxide values are as follows: Lard new has 4 and old has 26. Sunflower seed oil new has 60 and old has 25.Olive oil new has 22 and old has 34.

The results obtained on Friday (PM) are as follows: For the sample and duplicate, the titrated free fatty acid values are: Lard new has 12 ml and 13 ml, and Lard old has 17.5 ml and 16.4 ml, respectively. Sunflower new has 1.2 ml and 1 ml, and Sunflower old has 1.75 ml and 1.65 ml, respectively. Olive oil new has 3.55 ml and 3.10 ml, and Olive oil old has 4.8 ml and 4.5 ml, respectively. The average free fatty acid values are Lard (new) and old have 0.73% and 0.99%, respectively. Sunflower seed oil new and old has 0.06 % and 0.09 %, respectively. Olive oil (new) has 0.19 % and 0.27 %, respectively.

The titrated peroxide values are as follows: Lard new has 0.2ml and 0.2 ml, and Lard old has 0.7 ml and 1 ml, respectively. Sunflower seed oil has 0.9 ml and 0.5 ml, and Sunflower old has 1.4 ml and 1.25 ml respectively. Olive oil new has 0.35 ml and 0.35 ml, and Olive oil old has no value and 0.6 ml, respectively. The average peroxide values are as follows: Lard new has 4 and old has 17. Sunflower seed oil new has 14 and old has 26.5.Olive oil new has 7 and old has 12.

Discussion

Fats and oils have been widely believed as appetite inducing food ingredients. This is due to the fact that they have taste enriching properties. These are mostly preferred food items for frying.Due to that, they are extensively marketed in various brands. However, the old and new varieties of oils or fats exhibit a tendency of altering the organoleptic properties of fried food items. It was believed that old oils have some degrading characteristics and hence they are eliminated in most preparations.

This could because a natural phenomenon of degradation is operating as an underlying mechanism. Available studies have already described the association between frying and degradation. This could be the reason that indicates the limited applicability of old oils when compared to new oil. The proportions of various fatty acids in oils could show variation and in turn may determine the strength of oils.

Certain compounds facilitate the flavor stability and quality of the oil by hydrolysis, oxidation, and polymerization (Choe and Min, 2007). There is need to further carry out experiments that dissect the relation ship between the components present in the oil and oxidation. It is reasonable to mention that the organoleptic properties of chips are strongly influenced by the frying properties of oils and fats. As evidenced from the results, the imparted colors are white, dark white, yellow, light yellow and much darker yellow.

Old oils in Lard and Sunflower have contributed to some dark color of chips where as new oils have contributed to the white and light yellow. This may indicate that the certain substances in old oil might be slowly deteriorating and promoting the color degradation.

This could occur regardless of variation in taste and odor. But is highly important to determine the properties concerned with rancidity and peroxidation. For this purpose, peroxide value is used. which plays essential role in determining the rancidity and freshness of a given oil or fat. Hence its measure is suggested. Further, the role of antioxidants needs to be further understood. This is because autoxidation reaction influences the activity of peroxides (Naohiro Gotoh and Shun Wada, 2006). Here, the storage conditions could play important role. Next, the percentage of total free fatty acids in all the three oils is below the cut off value of 1%.This may indicate that the free fatty acids have not altered corresponding to the frying conditions.

It is unknown whether this property occurs to temperature used or the old or new variety of oil or fat. There is a need to further explore the role of free fatty acid variation in Lard, sunflower and olive oils. It was reported that frying generally accompanies moisture, heat and fat oroil transfer, crust formation and various structural, textural and chemical variations in the product, and degradation of frying medium (Paul and Mittal, 1997).

As it is difficult to monitor these conditions, researchers have emphasized on the role of suitable online frying oil quality sensor (Paul and Mittal, 1997). They further emphasized on the characteristics affecting oil penetration and absorption by the food, surfactant theory of frying, analytical indices, quick tests and acceptability of frying oil (Paul and Mittal, 1997). This report is reliable in providing the information and is best supporting for the current study to investigate the problems.

Next, the peroxide values have shown variation. On Monday experiment, Olive oil (new) has produced a value of 105 which is more than the cut off 100 in contrast to other oils. This may indicate olive oils show an increased tendency to get rancid when they were bought new and applied.

Further, the peroxide value of Lard and sunflower have shown variations. It can be assumed that certain opposing properties inherent in plant and animal fats or oils might contribute to the fluctuations in the peroxide values corresponding to the frying.

Oils containing docosahexaenoic acid (DHA) – may show variation in the stable peroxide levels of phospholipids (PL), trigcylglycerols (TG), and ethyl esters (EE) with the same constituent fatty acids (Song, Inoue & Miyazawa, 1997). This could be due to the differences more specific to the source of oil. In that report, palm oil supplemented with 20 % soyabean has negligible peroxide and carbonyl values compared to that obtained with TG and EE (Song, Inoue & Miyazawa, 1997).

Similarly, DHA-containing oil has shown a significantly low oxygen absorption in the form of PL than in the form of TG and EE (Song, Inoue & Miyazawa, 1997). These fluctuations may be due to the chemical nature of the components present in the oil. Here, it can be assumed that the type of single or double bond, or the functional group attached with the fatty acid may be playing a key role in determining the properties of oils.But this aspect needs thorough investigation and scientific evidence to prove. Hence more studies are suggestive to understand this particular aspect.

Next, it is also reasonable to connect this part of description with the health aspects keeping in view of the properties of oils and fats. It was reported that the health care professionals must include the counseling session in their regular practice to keep the patients informed of the adverse effects of hydrogenated oils and foods containing trans fats because of their link with Coronary Heart Disease (CHD) (White, 2009). Here it is important to know about the categories of fatty acids. These are saturated, monounsaturated, polyunsaturated, and trans fats. CHD result from the saturated fatty acids (White, 2009).

Monounsaturated fatty acids and polyunsaturated fatty acids are associated with a decreased risk of coronary heart disease, although these associations are not uniformly supported in the literature. However, there are also certain beneficial properties (White, 2009). Inflammatory conditions could be better managed by Omega-3 fatty acid which is a polyunsaturated fatty acid and was largely exploited in therapeutic conditions. The other known health benefits of Omega-3 fatty acids are it provides resistance against dementia and cystic fibrosis (White, 2009).

Conclusion

In view of the above information, it can be concluded that properties of oils and fats have a remarkable property of influencing the storage, delicacy of food products especially the organoleptic characteristics of chips. They should be consumed keeping in view of variety of fatty acid contents. Consumption fried chips need to be cautiously monitored. This is because these food items are commonly preferred in many nations (Mehta & Swinburn, 2001).It is unknown to many individuals who are other wise innocent about the high fat content and the associated diseases in societies with a high fat consumption (Mehta & Swinburn, 2001). Available research evidence has indicated the usefulness of determining the properties that contribute to the degradation. Peroxide values serve as better indices to determine the freshness of oils and fats.

A thorough understanding of these cut off indices should be practiced in household and restaurant preparations. This could help in minimizing the risk associated with The consumption of high fat diet.

The organopeltic properties of chips which are mostly frequently influence b the properties of oils and fats need to be monitored wit the aid of a sophisticated oil sensor. It is unknown whether how many countries are strictly adhering to the principles or guidelines releasing by the food authorities in the respective countries.

The composition of free fatty acid contents in the given oil or fat need to be printed on the labels. The conditions required for the frying should also need to be made aware to the general public. This practice better helps to manage the rancid conditions or degradative properties which play vital role in contributing to the generation of oxidants.

It is suggestive that oil and fats manufactures have better knowledge on basic chemistry with regard to antioxidant properties.

References

  1. Choe, E, Min, D.B. 2007. Chemistry of deep-fat frying oils J Food Sci, 72(5), pp. R77-86.
  2. Naohiro Gotoh and Shun Wada. 2006. The importance of peroxide value in assessing food quality and food safety. Journal of the American Oil Chemists’ Society, 83 (5),pp. 473-474.
  3. Mehta, U, Swinburn, B. 2001. A review of factors affecting fat absorption in hot chips. Crit Rev Food Sci Nutr, 41(2), pp.133-54.
  4. Chemical Reactions of Oil, Fat and Fat Based. Web.
  5. Paul, S and Mittal, G, S.1997. Regulating the use of degraded oil/fat in deep-fat/oil food frying. Crit Rev Food Sci, 37(7), pp. 635-62.
  6. White, B. 2009.Dietary fatty acids. Am Fam Physician, 80(4), pp. 345-50.
  7. Song, J, H, Inoue, Y, Miyazawa, T.1997. Oxidative stability of docosahexaenoic acid-containing oils in the form of phospholipids, triacylglycerols, and ethyl esters. Biosci Biotechnol Biochem. (12), pp. 2085-8.

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