The peroxide value is determined by measuring the amount of iodine which is formed by the reaction of peroxides (formed in fat or oil) with iodide ion. The base produced in this reaction is taken up by the excess of acetic acid present. The iodine liberated is titrated with sodium thiosulphate.
The Kreis test is a chemical method for quality evaluation of edible oils enabling early detection of rancidity. In previous studies, quantities of test oil and phloroglucinol, and incubation period were optimized for groundnut, rice bran and palm oils and efficiency of the test was improved.
The only direct method to measure oxidation, nitration, and sulfation is by spectroscopy. Indirect methods are viscosity and impedance measurements. Viscosity is the measure of a fluid's resistance to flow.
Saponification Value = (A - B)x N x 56.1 W This method is used to determine the total acid content, both free and combined, of tall oil. (Acid number only measures the free acid). The combined acids are primarily esters formed by reaction with the neutral components present in the original tall oil.
Carotenoids are colour materials occurring naturally in fats and oils. Most range in colour from yellow to deep red. The levels of most of these colour bodies are reduced during the normal processing of oils to give them acceptable colour, flavour, and stability.
abbreviation for total oxidation value; number used to describe the total oxidative load to which a fat has been exposed. The value is calculated as the sum of the anisidine value and twice the peroxide value.
Types of oils. Natural fats contain varying ratios of three types of fats: saturated, monounsaturated and polyunsaturated. Saturated fats are solid at room temperature and very stable. They resist oxidation, so they often can tolerate higher temperatures.
Slow Down OxidationHere are some tips for slowing it down. Limit deep-fried foods and don't reuse cooking oil. Store cooking oil, whole-grain flours and nuts in cool, dark places. Refrigerate polyunsaturated oils, especially fish, nut and flaxseed oils.
Peroxide value (PV). The PV is an indication of the amount of hydroperoxides present in an oil. These compounds arise from lipid oxidation; therefore, the PV, expressed as milliequivalent oxygen per kilogram oil (meq/kg), is a measure of oil quality.
Coconut Oil Has a Unique Composition of Fatty Acids
This makes coconut oil highly resistant to oxidation at high heat. For this reason, it is very suitable for high-heat cooking methods like frying ( 2 ).The Rancimat test determines the oxidation stability of oils in a very short time, however, high temperatures (50–150 °C) and intensive aeration are used, which change the nature of the oxidation process.
While all oils can become oxidized, “the more unsaturated the fat is, the more susceptible it is,” adds Decker.
When a cooking oil is exposed to heat, light and oxygen, it can oxidize. Oxidized oils can produce harmful compounds and toxic by-products and make your food taste bad. A greater induction time indicates an oil is more resistant to oxidation, a shorter induction time means the oil will oxidize easily.
The total oxidation (TOTOX) value was calculated as TOTOX = 2PV + p-AV, where PV and p-AV represent peroxide value and p-anisidine value, respectively (De Abreu, Losada, Maroto, & Cruz, 2010).
p-Anisidine (para-anisidine) is an organic compound with the formula CH
3OC
6H
4NH
2.
p-Anisidine.
| Names |
|---|
| Melting point | 56 to 59 °C (133 to 138 °F; 329 to 332 K) |
| Boiling point | 243 °C (469 °F; 516 K) |
| Solubility in water | Sparingly soluble |
| Solubility in other solvents | Soluble in ethanol, diethyl ether, acetone, benzene |
Since benzophenone can further delocalize this positive charge into its phenyl groups, the conjugate acid of benzophenone is the most stabilized of the three acids, leading to benzophenone being the strongest base.
Aniline is a liquid at room temperature and aniline hydrochloride is a solid and both are toxic substances (aniline is a suspected carcinogen).
Benzoic acid or benzene-carbonic-acid is a monobasic aromatic acid, moderately strong, white crystalline powder, very soluble in alcohol, ether, and benzene, but poorly soluble in water (0.3 g of benzoic acid in 100 g of water at 20 °C).
What is the melting point of benzophenone?
