Etiket Arşivleri: FE 272

Experiment: Determination of Fat

Name of Experiment            : DETERMINATION OF FAT

QUESTIONS

  • What is the principle of soxhelet extraction apparatus?

The principle of soxhelet extraction apparatus is to occur an intermittent extraction with excess of fresh condensed solvent in a special sample tube with a siphon attachment. The sample is held in a porous filter container such as thimble, and extracted fat returns with the solvent when siphoned, but does not redistill with the solvent and condense back to the sample.

  • What is the function of lipids on human body?

  1. They are source of energy.

  2. They need for vitamins that melted in fat.

  3. They need for Linoleic acid, Linolenic acid and Arachidonic acid because of certain of them cannot be made by the body. Essential fatty acids in lipids form part of the structure of all cell membranes.

  4. They preserve to body from out effects.

  • Define extractable fat and total fat.

  1. The extractable fat: The extractable fat is crude fat. It can be extracted by les polar solvents. Also, its amount is too much than other matters in food.

  2. The total fat: The total fat content consists of the additional ‘bound’ lipids which require more polar solvents (alcohols) for their extraction.

  • What is the function of acid added to the sample prior to the extraction?

The function of acid added to sample prior to the extraction is dissolved to proteins in lipids.

Laboratory‎ > Determination of Moisture Content ( Kenan ÖZ )

FE 272 FOOD CHEMISTRY LAB Experiment 1

DETERMİNATİON OF MOISTURE CONTENT

Name of Experiment            : DETERMINATION OF MOISTURE CONTENT

Number of Experiment       : 1

Submitted by                        : Kenan ÖZ

QUESTIONS

  • Define the moisture content.

The determination of moisture is one of the most important and widely used analytical measurements in the processing and testing of food products.

The moisture content is frequently an index of stability and quality, and is also a measure of yield and quantity of food solids. It is closely concerned with the economics and legal aspects of food processing.

The moisture content of foods varies considerably: for fresh fruits, from 65% in ripe avocados to 95% in rhubarb; for fresh vegetables, from 66% in green beans to 96% in cucumbers; for fresh meat and fish, from 50 – 75%. The moisture content of processed foods varies even more from about 7 – 12% for dried vegetables to 27 -35% for jams and jellies.

  • What is the relationship between water activity and moisture content?

Water activity is an important means of predicting and controlling the shelf life of food products. Shelf life is the time during which a product will remain safe, maintain desired sensory, chemical, physical and microbiological properties, and comply with nutritional labeling.

 The relationship between moisture content and water activity is complex. An increase in aw is almost always accompanied by an increase in the moisture content, but in a nonlinear fashion. This relationship between water activity and moisture content at a given temperature is called the moisture sorption isotherm. These curves are determined experimentally. Moisture sorption isotherms are sigmoidal in shape for most foods, although foods that contain large amounts of sugar or small soluble molecules have a J-type isotherm curve shape. A moisture sorption isotherm prepared by adsorption (starting from the dry state) will not necessarily be the same as an isotherm prepared by desorption (starting from the wet state). This phenomenon of different aw vs. moisture values by the two methods is called moisture sorption hysteresis and is exhibited by many foods. Many disciplines use water content calculations to regulate product quality, however, water content measurement can be inaccurate, time-consuming and require a precision balance.

  • Write the importance of monolayer value for the foodstuffs.

The importance of monolayer value for the foodstuffs is physically bound as monolayer the surface of the food constituents.

  • What are the advantages and disadvantages of each methods (drying, distillation, chemical and instrumental methods)?

  1. Drying Methods:

Advantages: Different temperature of drying may result in a different amount of free water loss, so it is important to compare results obtained using the same condition.

Disadvantages: Weight lost, volatile oils may be lost.

  1. Distillation Methods:

Advantages: It has advantages of needing little attention and do not separate with the water and so are not measured.

FE 272 Food Chemistry Lab Questions Exp 1 ( Kenan ÖZ )

Name of Experiment            : DETERMINATION OF MOISTURE CONTENT

Number of Experiment       : 1

Submitted by                        : Kenan ÖZ

QUESTIONS

  • Define the moisture content.

The determination of moisture is one of the most important and widely used analytical measurements in the processing and testing of food products.

The moisture content is frequently an index of stability and quality, and is also a measure of yield and quantity of food solids. It is closely concerned with the economics and legal aspects of food processing.

The moisture content of foods varies considerably: for fresh fruits, from 65% in ripe avocados to 95% in rhubarb; for fresh vegetables, from 66% in green beans to 96% in cucumbers; for fresh meat and fish, from 50 – 75%. The moisture content of processed foods varies even more from about 7 – 12% for dried vegetables to 27 -35% for jams and jellies.

  • What is the relationship between water activity and moisture content?

Water activity is an important means of predicting and controlling the shelf life of food products. Shelf life is the time during which a product will remain safe, maintain desired sensory, chemical, physical and microbiological properties, and comply with nutritional labeling.

 The relationship between moisture content and water activity is complex. An increase in aw is almost always accompanied by an increase in the moisture content, but in a nonlinear fashion. This relationship between water activity and moisture content at a given temperature is called the moisture sorption isotherm. These curves are determined experimentally. Moisture sorption isotherms are sigmoidal in shape for most foods, although foods that contain large amounts of sugar or small soluble molecules have a J-type isotherm curve shape. A moisture sorption isotherm prepared by adsorption (starting from the dry state) will not necessarily be the same as an isotherm prepared by desorption (starting from the wet state). This phenomenon of different aw vs. moisture values by the two methods is called moisture sorption hysteresis and is exhibited by many foods. Many disciplines use water content calculations to regulate product quality, however, water content measurement can be inaccurate, time-consuming and require a precision balance.

  • Write the importance of monolayer value for the foodstuffs.

The importance of monolayer value for the foodstuffs is physically bound as monolayer the surface of the food constituents.

  • What are the advantages and disadvantages of each methods (drying, distillation, chemical and instrumental methods)?

  • Drying Methods:

Advantages: Different temperature of drying may result in a different amount of free water loss, so it is important to compare results obtained using the same condition.

Disadvantages: Weight lost, volatile oils may be lost.

      Distillation Methods:

Advantages: It has advantages of needing little attention and do not separate with the water and so are not measured.

FE 272 Food Chemistry Lab Questions Exp 2 ( Kenan ÖZ )

Name of Experiment            : DETERMINATION OF FAT

Number of Experiment       : 2

Submitted by                           : Kenan ÖZ

QUESTIONS

  • What is the principle of soxhelet extraction apparatus?

The principle of soxhelet extraction apparatus is to occur an intermittent extraction with excess of fresh condensed solvent in a special sample tube with a siphon attachment. The sample is held in a porous filter container such as thimble, and extracted fat returns with the solvent when siphoned, but does not redistill with the solvent and condense back to the sample.

  • What is the function of lipids on human body?

  1. They are source of energy.

  2. They need for vitamins that melted in fat.

  3. They need for Linoleic acid, Linolenic acid and Arachidonic acid because of certain of them cannot be made by the body. Essential fatty acids in lipids form part of the structure of all cell membranes.

  4. They preserve to body from out effects.

  • Define extractable fat and total fat.

  1. The extractable fat: The extractable fat is crude fat. It can be extracted by les polar solvents. Also, its amount is too much than other matters in food.

  1. The total fat: The total fat content consists of the additional ‘bound’ lipids which require more polar solvents (alcohols) for their extraction.

  • What is the function of acid added to the sample prior to the extraction?

The function of acid added to sample prior to the extraction is dissolved to proteins in lipids.