Explain the principle of the method (anisidine test).

The principal method of the anisidine test could be explained as the secondary oxidation that could be focused as the fat matrix; the p-anisidine is the determining of the variation in the absorbance that could be measured in the 366 nm. The anisidine value also explained as the oxidation of oil or fat that is present in the aldehydes and ketones. From the AnV analysis, it is also analyzed that there is food in which indicator of excessive the oil deterioration is present. The anisidine tests are the things, which are involved in the deep frying process (Rex Bookstore, Inc., 2007)

(a) What are the primary and secondary products of oxidative rancidity?

The primary oxidation products are the alkyl radical reactions that are based on the reaction of the light or heat. In the primary oxidation, there are proxy free radical, peroxides, free fatty acid, dienes and also unsaturated fatty acid that unattacked. The initiation, termination as well as the propagation is also included in the autoxidation.

The Secondary oxidation involves the hydroperoxides decompose; there is the presence of heavy metals example, Cu, Fe and trienes, carbonyls, aldehydes. It also involves the heating, radiation as well as the radical initiating agents.

(b) Using a suitable equation show how the total oxidation number can be calculated.

There are three main groups of compounds that can be formed during the frying process of eatables. These groups of processes are hydrolysis, oxidation, and thermal alteration. The causative agents for hydrolysis is moisture, for oxidation is air, and for thermal alteration the temperature is deriving factor for the production of compounds. The oxidation process oxidizes monomeric triacylglycerols, oxidized dimeric compounds along with formation of oligomeric triacylglycerols. The formation of volatile compounds includes production of hydrocarbons, aldehydes and ketones (Vašková, et al., 2012). The oxidation number of each compound is mentioned below in the table.

(c) Briefly advise LSBU Best Canteen on how the process of oxidative rancidity can be retarded.

Oxidative rancidity can be retarded or delayed with the hydrolysis, lipids and auto-oxidation of fats.

(d) Discuss the factors that promote rancidity in fat-containing foods.

The factors that promote rancidity in the fat-containing foods are beta-carotene, vitamins C and E etc (Paquot, 2013).

QUESTION 2

You were presented with a sample of milk powder or sausage meat and were asked to estimate the fat content of the sample using the Soxtec method.

Draft a step by step analytical protocol for this determination. Your account must include the principle, materials, safety precautions and necessary calculations. The functions of the reagents and safety precautions should be described.

Introduction of milk powder and the sausage meat

The sample milk powder and the sausage meat can be used for the analysis of fat content. The content of fats in the milk have impact on the health of users. The estimation for the fat content in the dry milk powder can be done by using simple soxtec method. The total fats in milk is combination of triglyceride, wax ester, phospholipids, and sterols. The other components in the milk powder are non-fatty materials. The traditional process for the fats extraction in organic solvent is a quantitative process for the determination of fats. 

Principle of milk powder and the sausage meat

(c) Briefly advise LSBU Best Canteen on how the process of oxidative rancidity can be retarded.

Oxidative rancidity can be retarded or delayed with the hydrolysis, lipids and auto-oxidation of fats.

(d) Discuss the factors that promote rancidity in fat-containing foods.

The factors that promote rancidity in the fat-containing foods are beta-carotene, vitamins C and E etc (Paquot, 2013).

QUESTION 2

You were presented with a sample of milk powder or sausagemeat and were asked to estimate the fat content of the sample using the Soxtec method.

Draft a step by step analytical protocol for this determination. Your account must include the principle, materials, safety precautions and necessary calculations. The functions of the reagents and safety precautions should be described.

Introduction of milk powder and the sausage meat

The sample milk powder and the sausage meat can be used for the analysis of fat content. The content of fats in the milk have impact on the health of users. The estimation for the fat content in the dry milk powder can be done by using simple soxtec method. The total fats in milk is combination of trigylcerides, wax ester, phospholipids, and sterols. The other components in the milk powder are non-fatty materials. The traditional process for the fats extraction in organic solvent is a quantitative process for the determination of fats. 

Principle of milk powder and the sausage meat

The soxtec system is mainly designed for the replacement and the improvement of traditional organic compounds through the solvent process. The quantitative determination of the fats in the dry milk depends on the speed of extraction and gets special attention. The instrument used for the analysis is versatile and convenient for the solvent extraction. The first principle is to dry the material and remove moisture that restricts the combination of organic solvent in the dried sample and in present case the sample material is dried milk power. The size of the sample is reduced and surface areas is increased to make larger areas for the exposure to the surface. After the process of expanding sample is done the acidic hydrolysis is the next process. In acidic hydrolysis the breaking of protein fat emulsion is done and the process increases more availability of the fats in the solvent. The last step is distillation process to collect the solvents.    

Figure 1: Apparatus used for soxhlet extraction method (Mishra, 2017)      

Materials of milk powder and the sausage meat

Drying oven

Thimble

Weighing balance

Soxhlet apparatus

Heating mantle

Desiccator along with silica gel

Cotton plugs

Petroleum ether

Safety precautions

The solvents used in the process are flammable solvents so special care is required to handle the materials.

The cooling water used for the cooling process can represent safety hazards for the heat sources and electrical components.

The extraction time for the solvents should be measured carefully.

The solution is supercritical fluid so special care should be used for accelerated solvent extraction.

Method of milk powder and the sausagemeat

All the apparatus was rinsed first by petroleum ether and dried in the oven at approximately to remove moisture content.

The dried milk sample were grounded and placed in the thimble.

The thimble was placed in the soxhlet extractor.

The bottom flask was filled with 90 ml of petroleum ether.

The whole setting was placed on the heating mantle to increase the temperature of solution. The solution of petroleum ether was boiled and the extraction process continued for 6 hours.

The condensing unit was removed from the extraction unit and allowed the solution to cool down.

The solvent was passed through distillation process and desiccator was placed on the oven.

The weight of dried sample was measured and compared with the defeat sample

Calculations of milk powder and the sausage meat

QUESTION 3

You were presented with a sample of milk powder or sausage meat and were asked to estimate the protein content of the sample using the Kjeldahl method.

Draft a step by step analytical protocol for this determination. Your account must include the principle, materials, safety precautions and necessary calculations. The functions of the reagents and safety precautions should be described.

Kjeldahl Method

Principle

The Kjeldahl method do not determine the content of protein directly but the concentration of nitrogen in the samples can be determined that is directly related to the content of protein in the samples. Kjeldahl method is basicallly nitrogen combustion (Dumas) method for measurement of protein ratio in the dried milk powder. Kjeldahl method is basically combination of three parts including digestion, distillation, and titration (Discoverfoodtech.com, 2017).     

Material

Digestion flask

Catalyst (mercury, copper, selenium, titanium)

Ammonia gass

Organic matter

Digestion converter

Safety measures

The distillation process is important for the accurate measurement of nitrogen in the foods.

The correction factor needs to be accurately measured for all the amino acid sequences

The sulfuric acid is dangerous to health so it should not place on the high temperature.

The time consumed in the process should be measured accurately.   

Necessary calculation

The standard acid is used for the estimation of proteins in the powder milk (Itwreagents.com, 2018).

Reagent function

Sulfuric acid

Catalyst

Kjeldahl digestion tablets

Sodium hydroxide solution

Boric acid solution 

You were presented with a sample of milk powder or sausage meat and were asked to estimate the moisture content of the sample using the vacuum oven method.

Draft a step by step analytical protocol for this determination. Your account must include the principle, materials, safety precautions and necessary calculations. The functions of the reagents and safety precautions should be described.

Principle of weigh in the sample material before and after the equilibrium

The change of weigh in the sample material before and after the equilibrium is determined and estimates the content of moisture in the sample. The sample were dried in the oven under the specified conditions. The loss in the weight was measured, the drying process was done under the reduced pressure of (25 – 100 mm Hg) for the removal of volatile and water components. The decomposition was for 3 – 6 hr for the drying time (Ahn, et al., 2014). 

Material of weigh in the sample material before and after the equilibrium

Milk powder

Vacuum oven

Water

Thermometer

Forced draft oven

Lipid oxidation transformer  

Safety measures of weigh in the sample material before and after the equilibrium

The sample handling in the heated vacuum oven should be done carefully.

The boiling point should be measured precisely.

The sample weight in the specified time should done precisely.  

The other conditions for the precise measurement are

Type of oven used in the process.

Conditions of the oven working

Time and temperature measurement accuracy for samples 

Necessary calculation of weigh in the sample material before and after the equilibrium

References of weigh in the sample material before and after the equilibrium

Ahn, J. Y., Kil, D. Y., Kong, C. & Kim, B. G., 2014. Comparison of Oven-drying Methods for Determination of Moisture Content in Feed Ingredients. Asian-Australas J Anim Sci, 27(11), pp. 1615-1622.

Discoverfoodtech.com, 2017. Kjeldahl Method – Estimation Of Protein In Food. [Online]
Available at: http://discoverfoodtech.com/protein-estimation-by-kjeldahl-method/

Itwreagents.com, 2018. Nitrogen Determination by Kjeldahl Method. [Online]
Available at: https://www.itwreagents.com/uploads/20180114/A173_EN.pdf

Mishra, A., 2017. Soxhlet Extraction Method- Estimation Of Fat In Food. [Online]
Available at: http://discoverfoodtech.com/soxhlet-extraction-method/

Paquot, C., 2013. Standard Methods for the Analysis of Oils, Fats and Derivatives. s.l.:Elsevier.

Rex Bookstore, Inc., 2007. Nutrition and Dietetics' 2007 Ed.2007 Edition. s.l.:Rex Bookstore, Inc..

Vašková, J., Vaško, L. & Kron, I., 2012. Oxidative Processes and antioxidative metaloenzymes. In: s.l.:licensee InTec