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HNSC 1200 (29)
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Lecture 24

HNSC 1200 Lecture 24: Unit 5.1

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University of Manitoba
Human Nutritional Sciences
HNSC 1200
Snehil Dua

Fatty Acids and Processing Learning Objectives: Explain the difference (in structure, food sources and on health) between  saturated, unsaturated, and trans fat Explain the effects of processing on unsaturated fats cSD Course Notes: SEE FIGURE 12 Saturated:  Butyric acid – found in butter has 4 carbon atoms, single bonds and is saturated Stearic acid – found in beef has 18 carbon atoms, single bonds and is saturated  Palmitic acid –foundinpalm oilandcocabutter has16atoms,single bonds and is saturated Monounsaturatd Oleic acid found in olive oil and canola oil has 18 carbon atoms, one double bond and is unsaturated (monounsaturated) Polyunsaturated Linoleic acid has 18 carbons and 2 double bonds. It is found in most foods especially oilseeds such as canola and soybean Linolenic acid also has 18 carbon atoms but contains 3 double bonds and is found mostly in soybean and hempseed Linoleic and linolenic acids are essential fatty acids which we will look at in greater detail Effects of processing on unsaturated fats Unsaturated fatty acids can be found in both cis and trans form, dependent on their structure at the double bond. In the cis form, the hydrogen atoms on the double bond are on the same side as the double bond In the trans form, the hydrogen atoms are on opposite sides of the double bond from one another SEE FIGURE 13 Trans fatty acids have a higher melting point than the dis fatty acids Trans fatty acids can be found naturally in meat, poultry and processed milk products However, the majority of trans fatty acids in our diet are formed during the process of hydrogenation Hydrogenation Hydrogenation is a process where hydrogen is assed to unsaturated fatty acids (e.g., turning vegetable oil into hard margarine). The hydrogen attaches at the point(s) of unsaturation (the double bond), and the fatty acid becomes saturated (no longer has a double bond) This makes the fatty acid more solid t room temperature and increase the shelf life Points of unsaturation are more vulnerable to oxidation which is when oxygen mixes with the fat, causing it to go rancid, taste “off” That is why we store cooking oil in tightly sealed containers oSDP Therefore, the hydrogenated fats are more resistant to oxidation (no points of unsaturation), are more resistant to breakdown from high cooking temperatures and will have longer shelf life It also has a higher smoking point, so it more suitable for frying When the hydrogen is added, some of the unsaturated fatty acids become more saturated and the oil hardens and becomes easier to spread Once hydrogenated, the unsaturated fats lose their health benefits Hydrogenation affects not only the fatty acids in fats, but the vitamins as well For example, it decreases the activity of vitamin K in the body When unsaturated fatty acids are hydrogenated, some change shape instead of
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