determination of saponification value of fats and oils pdf

Determination Of Saponification Value Of Fats And Oils Pdf

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In practice a known amount of the oil or fat is refluxed with excess amount of standard alcoholic potash solution and the unused alkali is titrated against a standard acid. Reaction :. Reflux and condenser.

Dilini N. Perera, Geeth G.


Dilini N. Perera, Geeth G. Hewavitharana, S. Lipid oxidation has been identified as a major deterioration process of vegetable oils, which leads to the production of primary and secondary oxidative compounds that are harmful to human health. Oleoresins of ginger, garlic, nutmeg, pepper, cloves, and cinnamon were extracted and incorporated into coconut oil, and change occurrence on physicochemical properties, thermal stability, shelf life, and antioxidant activity was monitored against the same properties of pure coconut oil.

Lipid oxidation was assessed in terms of the free fatty acid level and peroxide value. For the comparison purpose, another oil sample was prepared by incorporating vitamin E too. Saponification value, iodine value, smoke point, and the flashpoint of flavored oil were decreased while increasing the viscosity during storage. The highest phenolic content and DPPH free radical scavenging activity were found in flavored coconut oil. Since spices containing antioxidants, the thermal stability of flavored oil was better than that of pure coconut oil.

Both oleoresins and vitamin E-incorporated samples showed the same pattern of increment of FFA and peroxide value during storage; however, those increments were slower than those of pure coconut oil. Fats and oils play a major role in the human diet. Apart from that, it also affects the sensory qualities of processed foods.

Coconut oil is one of the widely used cooking oil in many Asian countries [ 1 ]. Over the last decade, the world production of coconut oil has been increased because of its important edible characteristics. In the context of edibility, there are two types of coconut oil, RBD Refined, Bleached, and Deodorized and the virgin.

However, both contain similar fatty acids and a triglycerol profile [ 2 ]. The major fatty acid of coconut oil is lauric which is a medium-chain fatty acid MCFA [ 3 ]. MCFA are important as they act as inert sources of energy and are easier to absorb, metabolize, and store in the body [ 4 ]. As coconut oil is composed of more saturated FAs, it is more resistant to oxidation and polymerization than the oils with unsaturated fatty acids [ 2 ].

Lipid oxidation is a major deterioration process in cooking oils. It affects organoleptic properties as well as the keeping quality of oil-related food products. Several methods including genetic modifications, compositional changes via chemical means, and addition of synthetic antioxidants like TBHQ, BHT, and BHA have been practiced in order to improve the stability of edible oils [ 5 ]. Synthetic antioxidants are reported to be health hazardous, and some are removed from the GRAS generally recognized as safe list and banned in many countries.

Therefore, natural antioxidants such as oleoresins and volatile oils from spices and herbs have attracted a lot of attention in lipid oxidation. The addition of different spices and herbs to cooking oils was a traditional practice to enhance the aroma and taste of food particularly in Mediterranean cuisines [ 6 ].

Thus, they incorporated different spices and herbs such as ginger, garlic, nutmeg, cloves, cinnamon, and pepper for their recipes.

Therefore, they were able to make products with better shelf life and consumer preference due to the presence of natural antioxidants as well as an attractive flavor profile [ 6 ]. In keeping of those in mind, this study was conducted to develop flavored coconut oil by incorporating oleoresins of spices and analyzing effectiveness of it in terms of physicochemical properties, thermal stability, shelf life, and antioxidant activity against the same of pure coconut oil without incorporation of oleoresins.

Oleoresins of ginger, garlic, nutmeg, cloves, pepper, and cinnamon were purchased from a reputed internationally registered supplier in SL. Storage stability of oils was assessed by resorting the rapid aging test. A positive control of coconut oil in 36 bottles with vitamin E without oleoresins was also kept under the same condition for comparison purposes.

Samples were withdrawn at seven days of intervals for twelve weeks, and storage stability was analyzed in terms of peroxide value and FFA level. The total phenolic content of oil was analyzed according to the method of Redondo-Cuevas et al. Gallic acid was used as the standard to generate a calibration curve. Total phenolic content was expressed as a gallic acid equivalent using a linear equation based on the calibration curve.

To analyze the antioxidant activity of coconut oil, the method described by Pradhananga and Manandhar [ 11 ] was used with slight modifications. Thereafter, the mixture was vortexed for 30 seconds and left to react for 30 minutes in the dark. Sodium methyl ester of oil samples was prepared and transferred into the GC valves. After equilibration, the septum covering each vial was pierced with an SPME needle, and the fiber was exposed to the headspace for 40 minutes.

The volatiles adsorbed fiber was thermally desorbed in the hot injection port of a gas chromatograph. Helium was used as the carrier gas, at a flow rate of 0.

Statistical analyses were performed with Minitab statistical package version All the measurements are the mean value of triplicates. Pure and flavored coconut oil samples were analyzed concerning the following physicochemical properties, and results are given in Table 1. Therefore, there was a significant difference between FFA and PV of flavored and pure coconut oil samples.

The FFA level and PV of flavored coconut oil were decreased compared with pure coconut oil during storage. This may be due to the presence of oleoresins of spices which may have acted as natural antioxidants, and thus, they may prevent the oxidation of fatty acids [ 12 ].

According to Ghosh et al. Iodine numbers are often used to determine the amount of unsaturated fatty acids in oils. Unsaturated fatty acids are usually recommended for healthy consumption over a high percentage of saturated fatty acids in oils. However, highly unsaturated fatty acids in oils undertake an oxidative degradation process due to double-bond configuration unless enough antioxidant is added [ 14 ].

According to the data given in Table 1 , the iodine value of both pure and flavored coconut oils was and , respectively. Since the value of both samples was less than 0. This is maybe due to the diminishing of the double bonds in polyunsaturated fatty acids in coconut oil by chemical energy of oleoresins [ 15 ]. The saponification value SV of oil directly correlates with the average molecular weight of all the fatty acids present in it. Long-chain fatty acids found in the fats have a low saponification value because they have a relatively fewer number of carboxylic functional groups per unit mass of the fat as compared to short-chain fatty acids [ 16 ].

Therefore, there is a significant difference between the saponification value of flavored and pure coconut oil samples. The SV is related to the mean molecular mass of the fats and oils, and it is inversely related to the chain length of the fatty acids.

This means that the higher the SV, the shorter the average chain length of fatty acids [ 19 ]. However, in this study, one gram of flavored coconut oil contained a considerable number of oleoresins. Therefore, SV of flavored coconut oil gets a lower value, and this value is significantly lower than that of pure coconut oil.

The low moisture content is a requirement for a long storage life of oils; because moisture in oil causes hydrolyzation of triglycerides initially thereafter, it causes rancidity [ 14 ]. The moisture contents of all flavored and pure coconut oil samples of this study were within the range of 0. And it is for the edible coconut oil as per the Sri Lanka Standard Institution [ 21 ] 0. According to this study, the moisture content of flavored oil samples was increased after one week of storage. However, this increment was not significant because the calculated value of both samples was greater than 0.

The reason for this phenomenon was based on the ethanol base oleoresin extraction as it did not contain free water at all [ 22 ]. In insoluble impurities of flavored coconut oil which is the same as pure coconut oil samples , the value of all samples was higher than 0. Therefore, there is no significant difference between insoluble impurities in flavored and pure coconut oil samples. The smoke point of cooking oil is an important factor because heating of oil to a particular point may cause the oil to liberate smoke which may contain toxic fumes and harmful free radicals.

It is defined as the loss of small molecular fragments due to evaporation [ 23 ]. The smoke point and flashpoint of pure coconut oil subjected to this study were and , respectively, while these values for the flavored coconut oil in the same order were and. According to the results, the smoke point and the flashpoint of all the flavored coconut oil samples were decreased, and the value of all samples was less than 0.

Therefore, there is a significant difference between the smoke point and the flashpoint of flavored and pure coconut oil samples. Since boiling points of oleoresins are lower than the smoke point of coconut oil, the smoke point of oleoresin-incorporated flavored oil turned lower [ 24 ].

The viscosity of oils is depending on the nature of the triglycerides present in it. The viscosity changes due to the different arrangements of the fatty acids on the glycerol backbone of the triglyceride molecule. According to the results given in Table 1 , the viscosity of flavored oil was increased after the incorporation of oleoresins. Since the value of all samples was less than 0. The reason for the increment of the viscosity of the flavored sample was the addition of oleoresins, which are usually somewhat viscous [ 26 ].

The specific gravity of pure and flavored coconut oil samples was and , respectively. According to the results, the specific gravity of flavored oil was increased in comparison to the pure coconut oil, and the value of all oil samples was less than 0.

Therefore, there is a significant difference in the specific gravity of flavored and pure coconut oil samples. The reason for the increment of specific gravity of flavored oil samples was the addition of oleoresins, which are usually compact and dense comparatively pure oils [ 24 ].

Hence, the finding of Ghosh et al. After incorporation of oleoresins, the color of coconut oil was increased from pale yellow to dark brown while decreasing value from to. Hence, the darkness of flavored oil has been increased considerably. Further, redness of flavored oil has been increased from to while decreasing yellowness from to.

Therefore, when increasing the redness of flavored oil, the yellowness reciprocally comes down. The reason for the color change of flavored coconut oil was adding the oleoresin mixture which was usually dark in color. Apart from that, heating also caused to produce many decomposed products that are also dark in color. Similar findings have been reported in a color change of oils subjected to heating due to the accumulation of nonvolatile decomposition products such as oxidized triacylglycerol and FFA that can lead to color changes [ 5 ] which also indicates the quality deterioration of oil too.

Since oils are considered as the medium for frying of many food products, the oils must be thermally stable at the frying temperatures. Thermal degradation of oils at frying temperature results in several chemical reactions which include hydrolysis, oxidation, thermal decomposition, and polymerization [ 27 ].

Nevertheless, prolonged heating also reduces the organoleptic and nutritive quality of oils. FFAs are formed by the breakdown of triacylglycerol on hydrolytic or autoxidation. It has been reported that on thermal processing, hydrolysis occurs more in oil with short-chain fatty acids than oil with long-chain saturated fatty acids [ 28 ].

According to Figure 1 , FFA was found to be increasing with the increment of heating time of all oil samples subjected to this study.

Determination of saponification value of the given oil/fat.

Acid value of 11 samples was determined. The relative standard deviation of acid value for 5 replicates of each sample was less than 2. The method is superior to conventional titration methods in sensitivity and overcomes inaccuracy due to vagueness in color change of acidbase indicators in organic solvents. Most users should sign in with their email address. If you originally registered with a username please use that to sign in. Oxford University Press is a department of the University of Oxford. It furthers the University's objective of excellence in research, scholarship, and education by publishing worldwide.

In an actual laboratory setting, there are certain important steps that are not necessarily applicable in a virtual lab. Cite this Simulator:. Always wear lab coat and gloves when you are in the lab. When you enter the lab, switch on the exhaust fan and make sure that all the reagents required for the experiment are available. If they are not available, prepare the reagents using the components shown in the reagent preparation. Care should be taken while handling reagents like potassium hydroxide and hydrochloric acid. Accidental spills of these reagents will cause a severe itching sensation.

Animal and vegetable Oils, Fats and Waxes: PART IV. Testing

The present study aimed at characterizing the oil extracted from Bertholletia excelsa H. Analytical methods used for oils and fats were employed through pharmacopoeia assays, AOCS American Oil Chemists Society standard methods as well as those recommended by ANVISA National Health Surveillance Agency such as acidity, peroxide value, saponification index, iodine value and refractive index, pH and relative density, and also thermoanalytical analyses thermogravimetry, differential thermogravimetry and differential thermal analysis as well as chromatographic analysis gas chromatography. The characterization assessments of B. The termoanalytical tests indicated that B.

Triacylglycerols are composed of three fatty acids each in ester linkage with a single glycerol. Since the polar hydroxyls of glycerol and the polar carboxylates of the fatty acids are bound in ester linkages, triacyl glycerols are non polar, hydrophobic molecules, which are insoluble in water. Saponification is the hydrolysis of fats or oils under basic conditions to afford glycerol and the salt of the corresponding fatty acid. Saponification literally means "soap making". The amount of free fatty acid is estimated by determining the quantity of alkali that must be added to the fat to render it neutral.

Saponification value or saponification number SV or SN represents the number of milligrams of potassium hydroxide KOH required to saponify one gram of fat under the conditions specified. The higher the saponification value, the lower the fatty acids average length, the lighter the mean molecular weight of triglycerides and vice-versa.

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Saponification value
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  1. Olunpricfilm

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    06.04.2021 at 08:00 Reply
  2. Jerry P.

    Saponification value is expressed by potassium hydroxide in mg required to saponify one (1) gram of fat. It depends on the kind of fatty acid contained in the fat. Measurement of saponification value is performed according to the below listed official test methods. Here we test a sample of fatty acid.

    15.04.2021 at 13:11 Reply

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