The content
Introduction...6
Laboratory work # 1 Definition of oxidation of dairy butter. ..7
Laboratory work # 2 Quality assessment of bread and bakery products..9
Laboratory work # 3.Definition of physicochemical
parameters of sugar-beet. 10
Laboratory work # 4. Research of assortment and estimation
of mayonnaise quality...14
Laboratory work # 5.Quality determination of cocoa powder
nd chocolate....16
Laboratory work # 6 Definition of phenol compounds
in vegetable products....19
Laboratory work # 7.Definition of content of ascorbic acid
by iodimetric method... 21
Laboratory work # 8. Analysis of reducing properties
of ascorbic acid..24
Laboratory work # 9.Definition of fats mass share in cans by refractometric method
and total acidity in canned goods with sour fillings.....26
Laboratory work # 10.Definition of calcium content in food products.......30
Rules of safety measures...38
Literature...39
Introduction
In consequence of systematic study of discipline Processing productions safety students solve following objectives: safety of food products and their production from the point of view of health and reliability for the people and environment, estimation methods and safety criteria for food production, microbiological safety quotient of food production, risk of disadvantage or superfluity nutrient materials, danger of xenobiotics from ambient medium, main criterion of safety food additive, mainstream industry article development of food in I century, definition methods of content toxic elements in food products.
Laboratory workshops are connected with theory. On practicum students fortify obtained theoretical skills, get hand-on experience by definition of process specifications of preparation and delivery of ready-to-eat meal in accordance with applicable standards, norms and other scientific and technical documentation.
It is essential that students learn to economize chemical reagents, carefully refer to laboratory apparatus and facility, and follow regulations of personal hygiene and prophylaxis, safety procedures.
Laboratory work #1
Definition of butter fat oxidation level.
Purpose of the work: experimental determination of butter fat oxidation level
1.1. The task
1. Define oxidation level of dairy butter.
2. Calculate real optical density by formula.
3. Draw up report about the effort.
Theoretic part
Method is founded on formation of colored compounds of 2-thiobarbituric acid with some of secondary products of oxidation fat. Color grade depend upon oxidation rate of fat, as a result of which aldehydes form. Main of last is molon aldehyde. In absorption spectra of colored compounds there are two maximums, where the first (450 nm) corresponds yellow colored condensate of 2- thiobarbituric acid with monoaldehydes, but the second (535 nm) - red colored union 2- thiobarbituric acid with dialdehydes.
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The given reaction is widely used for degree evaluation of vegetable and animal fats oxidation, owing to high sensitivity, reproducibility and correlation of this index with organoleptic estimation of fat freshness. Due to the fact that mechanism of this reaction is unknown fully, analysis results are expressed by per unit of absorbance. Analysis of fat oxidation degree of various products with 2-thiobarbituric acid differs by distinction of sample preparation for measurement of absorbance by spectophotometer Especially it concerns the method for discriminating of fat.
Technique definition.
Chemical reagents: 1n spirit of salt; petroleum ether; reagent of 2-thiobarbituric acid; extraction mixture (isoamyl alcohol and 99% pyridine in balance of volumes 1:1).
Weighed portion of dairy butter (10g) is settled in centrifugal test-tube with stoppered and is hold in hot water with temperature 70-80 gr C during 3 min for complete fusion of milk fat. Next 2 ml of distil water,1 ml of 1n spirit of salt are added in test-tube, then it is shacked up strenuously, reheated 1 min and centrifugated 3 min (about 5000 rounds per min). Layer of milk fat is pipetted off. Water fraction is cleaned by several portions of petroleum-ether until disappearance of visible slosh. The ether every time is deleted by pipette with pumping out rubber bulb. In the end of flushing out contents test tube is centrifugated 2-3 min for more complete dissection of ether. 1,5 ml reagent of 2-thiobarbituric acid adds in caught-on of water fraction and then it is hold on boiling-water bath 15 min. Test tube is quenched to 18-20 gr C,
5 ml extraction mixture is added, then strenuously shaken and centrifugated 10 min by 5000 rounds per minute.
Clear color solution is carried over by pipette in cuvette 1cm,then optical density is measured under λ =490Nm, 535 Nm and 580 Nm. Control experiment is prepared in simulated conditions, but without butter, and 3,6 ml water instead 2 ml is added taking into account humidity of dairy butter.
Calculation of real optical density of colored compounds is carried by formula:
D=D535- D490+ D580,
where D535 - maximum absorption of colored compounds under λ =535Nm,
D490 D580 - minimal absorption in spectrum of determined colored compounds under λ =490Nm, 580 Nm, their optical density is minused for liberation from phone.
A report on task performance.
Student designs activity report. Accounting results are filled in table1.
| Product under investigation | Optical density λ= (nm), where | |||
| Dairy butter | 535 | 490 | 580 | |
Quiz:
1. Wherein does oxidation level of dairy butter consist?.
2. By what formula do you calculate real optical density of colored compounds?
3. By what does analysis of fat oxidation degree of various products with 2-thiobarbituric acid differ?
4. Why weighed portion of dairy butter is hold in hot water with temperature 70-80 gr C?
Laboratory work #2
Theme: an estimation of quality of bread and bakery products
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The purpose of job: To carry out an estimation of quality of the offered samples of bread and bakery products by organoleptical, physical and chemical parameters.
1.1. The task
1. Define an estimation of quality of bread and bakery products.
2. Learning of bakery products defects.
3. Draw up report about the effort
Theoretic part.
Potato bacillus, molding of bread and other diseases, called by wrong keeping and processing of charge stock, can induce diseases of man. In aid of food safety in the manufacture of bread it is necessary to use quality products, passed off microbiological and physicochemical check-out. End products also must compliant with standards.
