Free fatty acids, titration

This specification is for butter oil, which is butter with the water removed. The free fatty acid limit is to detect lipolytic rancidity while peroxide value specification is to limit oxidative rancidity. The copper limit arises because copper catalyses the oxidation of fats. The absence of neutralising substances is to prevent a high titration for free fatty acids being covered up by the addition of alkali. 

The saponification value is the amount of alkali required to saponify a defined amount of sample. It is expressed in mg potassium hydroxide (KOH) per g sample. The procedure involves the use of excess alcoholic KOH, which catalyzes the saponification/release of the free fatty acids from the glycerol backbone. The unreacted KOH is then back-titrated with standardized hydrochloric acid (HC1) using phenolphthalein as the indicator. The amount and normality of the HC1 used for neutralization can then be used to calculate the saponification value. The saponification value provides evidence as to the relative chain lengths of the fatty acids in the system. 

Frankel, E.N., Tarassuk, N.P. 1955. Extraction - titration method for free fatty acids in milk and cream. J. Dairy Sci. 38, 751-763. 

Landaas, A., Solberg, P. 1974. A simple extraction-titration procedure for the determination of free fatty acids in milk. Meieriposten 63, 497-506. 

Free Fatty Acids in Crude and Refined Fats and Oils (FFA) (Ca 5a-40) determines FFA, as oleic acid, by ethanolic sodium hydroxide titration. 

Free Fatty Acids (as oleic acid) Determine as directed under Free Fatty Acids, Appendix VII, using 28.2 as the equivalence factor (e) in the calculation for oleic acid. Titrate with the appropriate normality of sodium hydroxide solution, shaking vigorously, to the first permanent pink color of the same intensity as that of the neutralized alcohol (if the sample color interferes, titrate to a pH of 8.5, determined with a suitable instrument). 

Free Fatty Acids (as stearic acid) Transfer 2 g of sample, accurately weighed, into a dry, 125-mL Erlenmeyer flask containing 50 mL of acetone, fit an air-cooled reflux condenser onto the neck of the flask, boil the mixture on a steam bath for 10 min, and cool. Filter through two layers of Whatman No. 42, or equivalent, filter paper, and wash the flask, residue, and filter with 50 mL of acetone. Add phenolphthalein TS and 5 mL of water to the filtrate, and titrate with 0.1 A sodium hydroxide. Perform a blank determination (see General Provisions) using 100 mL of acetone and 5 mL of water, and make any necessary correction. Each milliliter of 0.1 A sodium hydroxide is equivalent to 28.45 mg of stearic acid (CigH gOi). Lead Determine as directed in the Flame Atomic Absorption Spectrophotometric Method under Lead Limit Test, Appendix NIB, using a 10-g sample. 

Free Fatty Acids Dissolve about 10 g of sample, accurately weighed, in 50 mL of a mixture of equal volumes of alcohol and ether (which has been neutralized to phenolphthalein with 0.1 N sodium hydroxide) contained in a flask. Add 1 mL of phenolphthalein TS, and titrate with 0.1 N sodium hydroxide... 

Alkali Refining This involves the determination of free fatty acids, phosphorus, and, if desired, chlorophyll, before and after the process. In addition, soap concentration is determined after water washing. Soap determination can present some difficulty in establishing the endpoint of the titration with oils high in chlorophylls, because of the dark color of such oils. 

A measured amount of oil is dissolved in ethyl alcohol and titrated with 0.1 N sodium hydroxide. For coconut oil, an equivalent term, percent free fatty acid... 

In calculating the amount of caustic required for caustic neutralization, the oil is titrated to a phenolphthalein end point. This titration endpoint includes not only the FFA, but also the oryzanol compounds. With the higher caustic addition, the ory-zanol is transferred to the soapstock away from the oil. The nutritional benefit of these compounds is lost. An alternative indicator for titration uses alkali blue (8). This indicator reflects the acidity contributed only by the free fatty acids. 

AS/. The AV is the number of milligrams of potassium hydroxide necessary to neutralize the acids in 1 g of lecithin (62). A product s AV is representative of the acidity contributed by both the phospholipids and any free fatty acids that are present. The AV is usually not indicative of pH, as the chemical nature of the phospholipid imparts buffering quahties to most systems. Lecithins typically exhibit a neutral pH value in aqueous media. An AV above 36 may indicate degradation of the lecithin because of improper processing or substandard quality soybeans. AV should not be confused with free fatty acid content, pH, or mineral acids. The correct method to assay for free fatty acids is to titrate only the acetone-soluble portion of the lecithin, whereby any contribution from the phospholipids in the acetone-insoluble portion is eliminated. AV is determined by the AOCS Official Method Ja 6-55 (77). 

ACM—alkaline contaminant material PCM—polar component material TPM—total polar material FFA— free fatty acid WET—water emulsion titratable. + Acid value. 

Free fatty acid (wt% as oleic) Determines free fatty acids in oil by titration with sodium hydroxide solution Ca 5a-40... 

Some of the traditional methods used for the characterization of bar soaps are moisture, free acid or free alkalinity, total soap, and chloride (salt). Moisture determinations are typically run by Karl Fischer titration. However, under certain circumstances, moisture can be measured gravimetric ally. The measure of free fatty acid or free alkalinity is typically done via a simple pH titration using phenophtha-lein or potentiometric end point. Total soap is generally done using an extraction/ gravimetric procedure the soap sample is acidified in an ethanol-water mixture, the fatty acids are extracted into a hydrocarbon solvent, and the amount of extracted... 

Refined, bleached, and deodorized palm stearine was obtained from CanAmera Foods (Toronto, Ontario, Canada) lard and canola oil were purchased from a local supermarket. Tween 80 was supplied by Quest International (Lachine, Quebec, Canada). Free fatty acid content was determined [as percentage oleic acid (w/w)] by titration (12). Free fatty acid contents were 0.03, 0.1, and 0.02%, respectively, for the lard, palm stearine, and canola oil. 

An insulin infusion should be considered for severe cases of calcium channel blocker toxicity." Case reports suggest that an intravenous bolus of regular insulin (0.5-1 units/kg) with 50 mL dextrose 50% (0.25 mg/kg for children) followed with a continuous infusion of regular insulin (0.5-1 units/kg per hour) may improve myocardial contractility. The effect of insulin is presently unclear, but it may improve myocardial metabolism that is adversely affected by calcium channel blocker overdoses, such as decreased cellular uptake of glucose and free fatty acids and a shift from fatty acid oxidation to carbohydrate metabolism. This insulin regimen is titrated to improvement in systolic blood pressure over 100 mm Hg and heart rate... 

J. O. Bosset, et. al., Determination of free fatty acids in milk and cream. Parts I and II, Evaluation of a collaborative study emplo3dng visual and potentiometric titration methods, Mitt. Geb. Lebenmittelunters Hyg., 81... 

The percentage of oil hydrolysis (POH) was determined by titration of the released fatty acids and defined as the percentage weight of free fatty acids in the sample, in comparison with the maximum theoretical amount of free fatty acids that could be produced if all the oil in the sample was hydrolyzed ... 

The total concentration of free fatty acids is usually determined by extrac-tion/titration methods or spectrophotometrically as Cu soaps. Early attempts to quantify the concentration of individual short-chain fatty acids involved steam distillation and adsorption chromatography. Complete separation and quantitation of free fatty acids can be achieved by GC, usually as their methyl esters, for which several preparative techniques have been published. Free fatty acids are major contributors to the flavor of some varieties, e.g., Romano, Feta, and Blue in the latter, up to 25% of the total fatty acids may be in the free form. Short chain fatty acids are important contributors to cheese aroma, while longer chain acids contribute to taste. Excessive concentrations of either cause off-flavors (rancidity) and the critical concentration is quite low in many varieties, e.g., Cheddar and Gouda. 

Any free fatty acid present in the substance to be examined, for example a sodium salt, will, by the procedure, be dissolved in acetone and hereafter titrate by hydrochloric acid (see equation below). The content of alkaline impurities is at or below the defined limit, and the excess of hydrochloric acid added will change the color of the indicator from blue to yellow. Of course any other alkaline substances present capable of neutralizing the added hydrochloric acid will act as free fatty acid bases. 

Determination of Free Fatty Acids.- A weighed quantity of the glycerine is shaken up with some neutral ether in a separating funnel, the glycerine allowed to settle, drawn off, and the ether washed with three separate lots of water. The water must have been recently boiled, and be quite free from CO 2. All the free fatty acid is now in the ether, and no other soluble acid. A drop of phenolphthalein is now added, a little water, and the acidity determined by titration with deci-normal baryta solution, and the baryta solution taken calculated as oleic acid. 

Combined Fatty Acid.- About 30 grms. of the glycerine are placed in a flask, and to it is added about half a grm. of caustic soda in solution. The mixture is heated for ten minutes at 150° C. After cooling some pure ether is added to it, and enough dilute H 2 SO 4 to render it distinctly acid. It is well shaken. All the fatty acids go into the ether. The aqueous solution is then removed, and the ether well washed to remove all H 2 SO 4. Afterthe addition of phenolphthalein the acid is titrated, and the amount used calculated into oleic acid. From this total amount of fatty acids the free fatty acid is deducted, and the quantity of combined fatty acids thus obtained. 

Analysis. Free fatty acids were ethylated in ethanol dehydrated with molecular sieves using gaseous HCl as the catalyst. Ethyl esters of fatty acids were analyzed on a DB-23 capillary column (0.25 mm x 30 m J W Scientific, Folsom, CA) connected to a Hewlett-Packard 5890 gas chromatograph (Avondale, PA) as described previously (19). The water content in the oil layer was determined by Karl Fisher titration (moisture meter CA-07 Mitsubishi Chemical, Tokyo, Japan). The contents (by weight) of free fatty acids and fatty acid ethyl esters were analyzed by a thin-layer chromatography/flame ionization detector... 

This is a measure of the free fatty acid content of an oil and is expressed as the number of milligrams of KOH required to neutralise the free fatty acids of 1 g of the oil. A measured amount of oil is dissolved in a suitable solvent or mixture of solvents and titrated against the standard (deci-normal) KOH solution in the presence of phenolphthalein as an indicator. The acid value of the oil is calculated as follows ... 

In the lUPAC method 2.201 (Paquot, 1979a), two methods are described for the determination of the free fatty acid content acid value by the indicator method , a method comparable to the method described in Section 6.2.9, and acid value by the potentiometric method . In the latter method, the free fatty acids are titrated potentiometrically in a non-aqueous medium with a solution of potassium hydroxide in isopropanol. This method is employed for the determination of free acidity in highly coloured oils and fats. 

Composition of oil/fat. To study the composition of oil/fat it is essential to test the purity of an oil/ fat for adulteration, accidentally or voluntarily. The specific fatty acid in fat can be determined by GC by preparing methyl esters with sodium methoxide. Mass spectrometry coupled to GC (GC-MS) is the most powerful tool for identification of fatty acids separated by GC. Free fatty acids in oil (index of rancidity) can be determined by titration against standard alkali. Infrared (IR) spectroscopy, Raman spectroscopy, and ultraviolet (UV) spectroscopy (200—400 nm) are used to detect isomers (trans and cis) of unsaturated fatty acids and conjugated double bonds. It is important to study saponification value (depict fatty acid chain length), iodine value (give the degree of unsaturation), and hydroxyl value (free fatty acids present in fats). 

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