Chemical Properties of Food Chapter

To convert them into a semi-solid fat suitable for use in spreads.

It reduces the content of polyunsaturated fatty acids significantly.

An increase in melting point and an increase in oxidative stability.

<p>A mixture of cis and trans 18:1 isomers, referred to as 'oleate'.</p> Signup and view all the answers

<p>Because they contain a considerable proportion of trans 18:1 fatty acids formed during the hydrogenation process.</p> Signup and view all the answers

<p>They raise LDL levels and lower HDL levels in the body.</p> Signup and view all the answers

<p>Modifications of the hydrogenation process and interesterification of suitable blends.</p> Signup and view all the answers

<p>It helps consumers make informed choices regarding their dietary intake of trans fats.</p> Signup and view all the answers

<p>The presence of emulsions of lipids and aqueous systems complicates oxidation inhibition.</p> Signup and view all the answers

<p>It controls the chemical structure of volatile short-chain compounds, influencing flavor and odor.</p> Signup and view all the answers

<p>Antioxidants protect oils and fats against autoxidation, thus enhancing their stability.</p> Signup and view all the answers

<p>Natural antioxidants are often already present in oils, while synthetic antioxidants must be added to meet demand.</p> Signup and view all the answers

<p>Trienes oxidize faster than dienes, producing volatile aldehydes with lower threshold values.</p> Signup and view all the answers

<p>Different tocols have varying antioxidant activities, making total content alone an inadequate measure.</p> Signup and view all the answers

<p>One fragment remains attached to glycerol while the methyl end offers a volatile component.</p> Signup and view all the answers

<p>The three stages are initiation, propagation, and termination.</p> Signup and view all the answers

<p>Some natural antioxidants may be lost during refining, resulting in less stable refined oils.</p> Signup and view all the answers

<p>The ratio of reaction rates is 30,000 for oleate and 900 for linolenate.</p> Signup and view all the answers

<p>Higher concentrations may cause tocopherols to act as pro-oxidants, undermining their protective role.</p> Signup and view all the answers

<p>The distribution of antioxidants and pro-oxidants between oil and water phases is crucial for stability.</p> Signup and view all the answers

<p>Short-chain fragments attached to glycerol are likely to remain post-refining.</p> Signup and view all the answers

<p>Keeping hydroperoxides and metal ions apart can be assisted by controlling pH and selecting appropriate emulsifiers.</p> Signup and view all the answers

<p>Triplet state oxygen is involved in autoxidation while singlet state oxygen is linked to photo-oxidation.</p> Signup and view all the answers

<p>Natural antioxidants can be found in the leaves or seeds of certain plants.</p> Signup and view all the answers

<p>Soybean oil is the primary source of fats, and it is rich in polyunsaturated fatty acids.</p> Signup and view all the answers

<p>These products may be labeled as containing zero trans fats.</p> Signup and view all the answers

<p>'Hardstock' is produced through complete hydrogenation of unsaturated acids to convert them to saturated analogues.</p> Signup and view all the answers

<p>Changes include hydrogenation of unsaturated centers, stereomutation to higher-melting trans isomers, and double bond migration.</p> Signup and view all the answers

<p>Intermediate states DH and MH are formed during the half hydrogenated stages and are essential for the conversion process.</p> Signup and view all the answers

<p>The first step in the conversion of D to M is rate-determining, which results in low levels of DH.</p> Signup and view all the answers

<p>The levels of DH will be low, and the conversion of DH back to D will be slow.</p> Signup and view all the answers

<p>The typical iodine value of hardstock is around 2, indicating very low levels of unsaturated fatty acids.</p> Signup and view all the answers

<p>The primary vitamin E form found in soybean oil is $γ$-tocopherol.</p> Signup and view all the answers

<p>Wheat germ oil has the highest total vitamin E content at 254 mg/100 g.</p> Signup and view all the answers

<p>Palm oil contains both tocopherols and tocotrienols.</p> Signup and view all the answers

<p>Sesame oil is distinguished by its content of compounds such as sesamin, sesamolin, and sesaminol.</p> Signup and view all the answers

<p>Butter has the lowest vitamin E content with only 2 mg/100 g.</p> Signup and view all the answers

<p>Cyclisation, geometrical isomerism, and polymerisation can occur.</p> Signup and view all the answers

<p>Olive oil contains 22 mg/100 g of vitamin E, while corn oil contains 78 mg/100 g.</p> Signup and view all the answers

<p>The total vitamin E content calculated in IU accounts for the effect of each tocol on vitamin E activity.</p> Signup and view all the answers

<p>Linolenic acid undergoes stereoisomerism quicker than linoleate at temperatures above 220ºC.</p> Signup and view all the answers

<p>Cottonseed oil has a tocopherol content of 78 mg/100 g.</p> Signup and view all the answers

<p>Glycerol esters are broken down into fatty acids and glycerol.</p> Signup and view all the answers

<p>Lipolysis refers to the hydrolysis of fats by lipases, splitting glycerol esters into fatty acids and glycerol.</p> Signup and view all the answers

<p>Their all-cis pattern is essential for maintaining their nutritional value.</p> Signup and view all the answers

<p>Polymerisation results in the formation of dimers, trimers, and oligomers with increased molecular weight.</p> Signup and view all the answers

<p>Special analytical methods tailored to identify specific changes like isomerism and polymerisation may be needed.</p> Signup and view all the answers

<p>The risk increases significantly at temperatures exceeding 180ºC.</p> Signup and view all the answers