FOOD ENGINEERING

Bu sitede ara

En son site faaliyeti

Food Quality Control‎ > ‎Laboratory‎ > ‎

Fats & Oils


Purpose: 

In this experiment we tried to analyze fats and oil to observe some quality parameters and interpreted the some differences between each other.

Theory: 

The primary focus of the fats and oils laboratories is on value-added products resulting in cost effective oilseed processes, feedstocks and product performance in the marketplace. In addition, basic chemical analysis procedures and methodologies are applicable to other food, feed and nonfood compositions.

The analytical laboratory is equipped with both instrumental and wet chemistry applications suitable for defining physical and chemical characterization of fat and oil compositions. Typical equipment and allied glassware include gas chromatograph, Mettler Dropping Point, OSI (oxidative stability apparatus), Lovibond Tintometer, refractometer, Soxtec extractor, Cleveland Open Cup, kinematic viscosity, bomb calorimeter, Brookfield viscometer, CEM microwave moisture analyzer, differential scanning calorimetry and HPLC capability. While the primary focus is support to fat and oil related projects, these capabilities are applicable to analysis of food and non-food materials containing carbohydrates, proteins and other minor components.  The analytical laboratory can be characterized as a general chemistry facility with resources to provide support to AURI projects, clients and collaborators.

The process laboratory employs both a wet process area and a chemical processing area. The laboratory is equipped with reactors suitable for pressures ranging from atmospheric to 500 psi and in volumes of 0.5-1.0 liters and five gallons for scale-up studies. Research techniques include esterification, hydrogenation, refining, bleaching, distillation (Rotavap and short path) and deodorization. We also have a bench scale DeSmet crystallizer and membrane filter press for fractionation and extraction studies. Studies requiring preparation of materials by frying (pressure and electrical friers) can also be accommodated.

Formulations of both food and non-food products are developed in the formulation laboratory. Equipment includes scales, balance, mixers, blenders and product stability analysis at temperatures of ambient, 37 degrees and 100 degrees.

Technical staff for this operation includes a chemical specialist with organic and analytical specialty, an analytical chemist with food and feed expertise and a scientist with background in fats and oils, appropriate chemistries, foods and non-food applications.

Properties of Fats and Oils

FOR an understanding of the place of fats and oils in the diet and in the arts, some elementary knowledge of their chemical and physical properties is essential. It is the object of this section to present the minimum of such necessary information in the simplest way practicable. For complete treatment of the chemistry of fats and oils see J. Lewkowltsch, Chemical Technology and Analysis of Oils, Fats, and Waxes (London, Macmillan, 1922, 3 vols., 6th edition).

Chemical Composition

As already stated, fats may be decomposed into glycerin and fatty acids. This manner of decomposition takes place only in the presence of moisture. For each molecule (a molecule is the smallest particle of a substance that can exist and still exhibit the properties of that substance) of glycerin set free there are set free three molecules of fatty acid. In the process three molecules of water are taken up, partly to help re-form the glycerin and partly to help re-form the fatty acids. Conversely (in the laboratory) the fat may be reconstituted from glycerin and fatty acid, in which event three molecules of water are set free for each molecule of fat synthesized.

The process of splitting a substance whereby water is taken up is known to chemists as hydrolysis, a word which is merely Greek for cleavage by water. The process is often termed saponification, since it was first observed to take place in the manufacture of soap. The term saponification (instead of the more exact term hydrolysis) is, however, applied indiscriminately and inappropriately to any chemical change of this nature, whether or not soap is formed. Nowadays in industry fats are very often converted into glycerin and fatty acids -- that is, hydrolyzed -- without the formation of any soap whatever. A soap is merely the combination of a fatty acid with a metal, i.e., it is a salt. The commonest soaps are the fatty-acid salts of sodium (sodium is a soft, white metal obtained from common salt, sodium chloride) and potassium. (Potassium is also a soft, white metal obtained from wood ashes or from certain minerals found in Germany, Alsace, and elsewhere. Both sodium and potassium oxidize with great rapidity when exposed to the air, and hence are never found in nature except in the form of their compounds.) Hard soaps are sodium salts; soft soaps, potassium salts. The fatty-acid salts of ammonium are also sometimes used for cleansing. Only a few other soaps are of practical importance, for example lead soaps which are used in medicinal plasters, zinc soaps which are used in ointments, and aluminum soaps which are used in waterproofing. Very few of the salts of fatty acids have the properties of common soap. Most of them are but slightly soluble in water, and therefore do not yield suds and have little or no detergent (i.e., cleansing) action. All are nevertheless termed soaps by chemists.

Materials: 

Burette, Bunsen burner, pipette, flask, Erlenmeyer flask, oil, margarine, KOH, NaOH,Na2S2O3, phenolphthalein

Procedure:

-Determination of saponification Value of oil: 

About 2g of the oil or melted fat into flask was weighed out. Exactly 25ml of 0.5N alcoholic KOH solution was added. The reflux condenser and immerse the flask in boiling water for 60min was attached the flask frequently during the heating was swirled. After the refluxing, 0.5ml of 1%phenolphthalein was added and titrated very carefully, whilst still hot, with 0.5N HCI. If the volumes of 0.5 N HCl was used for sample and for blank.

-Determination of Free Fatty Acid: 

20ml of alcohol with 20ml of diethyl ether was mixed,1ml of phenolphthalein indicator was added. The mixture was neutralize by adding 0.1N NaOH from a burette.5g of sample into a baker-flask was weighed out. Then the solvent to the oil was added, swirled and titrated with 0.1N NaOH until a pink color persists for 30 sec. If two layers was separate and the titration using a smaller amount of samples was repeated. If V is the 0.1N NaOH used and the weight of sample taken.

-Determination of the Iodine Value of oil by Hanus Method: 

0.5g sample into a 250 ml flask was weighed.10ml CCl4 and 25 ml Hanus solution was added. And a blank was carry out at the same time. Let stand it 1h in a dark place.20ml of 10% KI solution was added, shaked though and added 100ml of distilled water. After 10min the solution was titrated with 0.1N Na2S2O3 solution until the color is changed from brown to yellow. At this point, starch solution was added and titration was continued until the blue-starch iodine color disappears. The iodine value was calculated by using the equation.

-Determination of Refractive index:

One drop of the sample was put on a refractometer prism. And the refractive index was read.

-Determination of Peroxide Value:

5g of sample was weighed into a 250ml erlenmayer flask. If your sample is margarine, melt it at about 40 OC avoiding excessive heating. And 1ml of saturated KI solution was added. The flask was swirled for 1min.Then 25ml of 3/2 Acetic acid chloroform was added into it. After this it was shaking and placed to a dark place. Then wait for 5min.And then 75 ml of water was added. And 1ml of 1% starch solution was added into it. Finally it is titrated with 0.1N sodium thiosulphate.

Discussion: 

Fats and oils may be split into glycerin and fatty acids, the resulting mixture containing three molecules of fatty acid for each molecule of glycerin. These three molecules of fatty acids are also named as triglycerides. Since there are a number of different fatty acids that occur in natural fats, a great many different triglycerids are encountered in nature. These are named according to the fatty acid or acids they contain.

Several analyses are made to understand the quality of fats and oils. In our experiment we analyzed different types of fats and oils (olive oil, margarine, butter, corn and sun flower oil) to observe if there are any defects in oils and fats that we eat in our daily life. The tests that were made:

  • Peroxidase determination
  • Refractive index
  • FFA determination
  • Iodine number determination
  • Saponification value determination

In our experiment the butter were used by our group A11. We estimated the iodine number as 72.3 .The iodine number of a fat tells us the degree of unsaturation of a fat. The determination of unsaponifiable matter must not be confused with the saponification number of a fat. The saponification number is the number of milligrams of potassium hydroxide required to convert one gram of the fat completely into glycerin and potassium soap. It gives information concerning the character of the fatty acids of the fat and in particular concerning the solubility of their soaps in water. The higher the saponification number of a fat free from moisture and unsaponifiable matter, the more soluble the soap that can be made from it. The saponification number that was calculated by us was 49,037.

Fats often become decomposed and rancid and that they then contain free fatty acids -- i.e., acid uncombined with glycerin. It was also pointed out that it is important to the industrial user to know the amount of free fatty acid present, since this determines in large measure the refining loss. The amount of free fatty acid is estimated by determining the quantity of alkali that must be added to the fat to render it quite neutral. Sometimes, in addition to estimating the free fatty acid in this way, the actual loss in refining is also determined.

Many crude fats as they come upon the market are either naturally or have become so through decomposition. Since for many uses such fats must be decolorized, the ease with which this may be done is an important factor in determining their commercial value. Many fats and oils contain substances that are not triglycerides. These may be natural constituents or they may be adulterants or contaminants. The presence of a considerable proportion of them of course reduces the commercial value of the fat. The commonest of these is moisture.

Finally, the viscosity of a fat is a property of commercial significance, especially to manufacturers of lubricants. It is usually estimated by comparing the length of time it takes a given volume of oil (or melted fat) to flow through a tube of small bore, or through a small orifice, with the time it takes an identical volume of water. Olive oil has the highest viscosity of any of the common vegetable oils. The viscosities vary greatly with the temperature. When fats are cooled to the solidifying point they can no longer be said to be viscous. They have become plastic.