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FDSN 507 Midterm 2
Lipid Analysis
| Physical characteristics, iodine value, saponifcation value, and free fatty acids are all methods to analyze ______. | bulk fat or oil |
| Measuring present status and evaluating stability are methods to analyze _____. | lipid oxidation |
| GC and TLC are methods to analyze _____. | lipid fractions |
| Fat ____ with solvents is typically required before fat _____ if not bulk fat or oil. | extraction, chracterization |
| Name three ways to minimize oxidation of fats. | Addition of antioxidants, flush with nitrogen, avoid heat/light. |
| Name three physical characterization methods for bulk fats and oils. | Refractive index, melting point, cold test, cloud point, spreadability. |
| Solid fat index is measured using _____ and is plotted as ____ vs _____. | dilatometry, volume, temperature |
| Solid fat content is measured using continuous wave or pulsed _____. | NMR |
| _____ can be used to determine the actual percentage of fat in a sample. | SFC (solid fat content) |
| _____ is a measure of degree of unsaturation. | Iodine value |
| Define iodine value. | The number of grams of iodine absrobed by 100 g of sample. |
| _____ gives the average molecular weight of triglycerides in a sample. | Saponification value |
| Define saponification value. | The number of mg of KOH required to saponify (give salt and glycerol) 1 g of sample. |
| _____ measures the fatty acids liberated upon hydrolysis of triglycerides. | Free fatty acids |
| ____ are an indication of adequacy of refining. | Free fatty acids |
| ____ are the primary products of oxidation. | Peroxides |
| Define peroxide value. | Number of mEq of peroxides per 1 kg sample. |
| A freshly refined or very rancid oil will have a peroxide value of ____. | zero |
| _____ estimates the amount of unsaturated aldehydes (secondary oxidation products) in a sample. | p-anisidine value |
| _____ indicates total oxidation using both peroxide and p-anisidine values. | Totox value |
| _____ is a secondary oxidation product responsible for off flavors/odors. | Hexanal |
| T or F: Lipid extraction is required for hexanal measurement. | False |
| The TBARs test measures a secondary oxidation product known as _____. | malonaldehyde |
| What is the disadvantage of TBARs test? | Method is not very sensitive. |
| T or F: TBARs correlates better with sensory evaluation than peroxide value. | True |
| ____ is usually used to measure lipid oxidation in meat products. | TBARs test |
| Conjugated dienes absorb at ____ nm. | 232 |
| Conjugated trienes absorb at ____ nm. | 270 |
| How should oxidative stability be evaluated? | 1. Subject sample to oxygen or heat 2. Monitor oxidation over time with present status test. 3. Determine the induction period before rancidity. 4. Use accelerated shelf-life studies |
| What can be fractionalized with gas chromatography? | Fatty acids, trans isomers, glycerols, cholesterol |
| What can be fractionalized with IR? | Trans isomers |
| What can be fractionalized with HPLC? | Glycerols, lipid soluble pigments/vitamins |
| What can be fractionalized with TLC? | Glycerols |
| How is Olestra analyzed in lipid fractions? | Lipase enzyme is used to breakdown triglycerides and then is precipitated with calcium. |
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