Learning Activity 3
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ScribdTranslationsLearning Activity 3
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ScribdTranslationsLEARNING ACTIVITY 3: INTERPRET THE PHYSICOCHEMICAL AND MICROBIOLOGICAL ANALYSIS
OF FOODS ACCORDING TO QUALITY STANDARDS
1. Do you consider food quality analysis important, why?
Yes, of course, through this process we are able to evaluate food products with
the end of determining whether they are free of contaminants and free of pathogens,
therefore, it is estimated that they are in suitable conditions to be consumed, without
the risk of ingesting infections or perhaps poisoning.
2. Do you know of any quality analysis conducted on food? Describe it.
It is important to say that there are different types of analysis in food in which
we must take samples directly from the plant emphasizing the
surface where the work is carried out, the way they are manipulated, the state of
the raw material and the finished product.
The analysis positions carried out on foods are:
Physico-chemical control
Organoleptic control
Microbiological control
Control of medication waste
Detection of pollutants
Detection of transgenic organs.
DESCRIBE THE TESTS FOR THE ANALYSIS OF MILK AND A PASTEURIZED EGG.
Responsible for the color, flavor, and smell of MILK.
Cow's milk, considered one of the most complete foods, has properties
Organoleptic characteristics considered; however, there are responsible components.
of color, flavor, and smell that we must know.
Reduction of methylene blue and test of resazurin.
It allows for the establishment of microbial quality in both untreated milk and in milk.
pasteurized. They are based on the reducing capacity of microorganisms. The dyes
if they are modified, there is growth. The change is observed immediately and is faster than
the bill on the plate.
2. Phosphatase test.
It is used to verify the pasteurization process. It is based on the inactivation of the
alkaline phosphatase by the procedure, being more resistant than the organisms
pathogens.
There are several methods:
a) With sodium p-nitrophenyl phosphate that goes from colorless to yellow due to the release of
nitrophenol at 37 C for 2 hours, the test is satisfactory when less than
10 pg of nitrophenol/ml of milk.
b) With disodium phenyl phosphate with the release of phenol, which is reacted with
dibromoquinone-chlorimide, to produce blue indophenol.
COLOR
the color WHITE is attributed to the reflection of light by the particles of the CASEINATE complex -
CALCIUM PHOSPHATE, in colloidal suspension and by fat globules in emulsion.
If the milk has a BLUISH WHITE color, it is because it has been partially or totally
skimmed or adulterated with WATER.
If the milk shows a WHITE-PINK color, it is due to the presence of blood or growth.
of microorganisms.
FLAVOR:
It is considered slightly sweet due to the lactose content. If the milk has a slight flavor.
salty is due to the presence of CHLORIDES that occurs in cow's milk at the end of the period of
lactation or due to infectious states of the udder, mastitis. At other times the taste is sour.
when the acidity percentage in the product is higher than 22-33 ml N of NaOH 0.1 N/100 ml (0.2-0.3% d
of lactic acid) but in general the taste of normal fresh milk is pleasant and can be described
simply as a characteristic.
COLOR:
It must be characterized by the presence of low molecular weight volatile organic compounds.
such as acids, aldehydes, ketones, and traces of methyl. Milk can easily acquire
strange flavors or odors, derived from certain foods consumed by the cow before being
milked, the substances of the penetrating smell or metallic surfaces with which it has been in
contact or chemical or microbiological changes that the product may undergo
during its handling.
What is electrometry?
Identify any coagulation of the milk, this is a very subjective test so for
Being able to accept or reject a product is necessary to consider the results of others.
tests.
Acidity test
The determination of the pH of milk is carried out directly on it with the help of a pH meter.
Metro... the pH of milk is inversely proportional to Dornic acidity, that is, the higher the acidity...
Lower acidity pH. The normal pH of milk is between 6.6 and 6.8.
Lacto-fermentation
also known as lactic fermentation, is an ancestral method of processing
foods. During the fermentation process, lactic acid bacteria transform the
sugars in lactic acid and in various components that limit the development of harmful bacteria.
Milk can be subjected to tests of:
Quantity - measure of volume or weight
Organoleptic characteristics: appearance, taste, and smell
Composition characteristics: especially of fat matter contents, of solid matter.
and proteins
Physical and chemical characteristics
Hygienic characteristics: hygienic conditions, cleanliness and quality
Adulteration: with water, preservatives, added solids, among others.
Drug waste.
EGGS:
the tests conducted for the analysis of a pasteurized egg is the thermal treatment the
inactivation of alpha-amylase.
Additives used in egg pasteurization so that it does not change color:
The formation of iron sulfide can be avoided with proper, not excessive cooking, and
using fresher eggs (the pH of the egg increases with age)
To avoid color change in pasteurized egg, the following additives should be added.
food-related:
Nisin 234. It is used as a food preservative, it can reduce the temperature of
thermal treatment improves the nutritional value, appearance, flavor, and texture of food
in addition to increasing the product's shelf life.
Potassium sorbate E-202: it is a preservative of natural or artificial origin
Sodium benzoate E-211: it is a synthetic preservative derived from benzoic acid.
Triethyl nitrate E-1505: it is a solvent for additives and synthetic aromas, it can be obtained
through genetic engineering. It is produced from citric acid.