Breed method is a laboratory technique used for counting microorganisms in milk. It was introduced in 1910 by American
biologist
A biologist is a scientist who conducts research in biology. Biologists are interested in studying life on Earth, whether it is an individual Cell (biology), cell, a multicellular organism, or a Community (ecology), community of Biological inter ...
s
Samuel Cate Prescott
Samuel Cate Prescott (April 5, 1872 – March 19, 1962) was an American food scientist and microbiologist who was involved in the development of food safety, food science, public health, and industrial microbiology.
Early life
Prescott was bo ...
and
Robert Stanley Breed.
Purpose
It is a method for somatic cell count, to know the number of living and dead microorganisms. When the method only recounts living organisms is called "viable count".
There are many methods for the quantification of
microorganism
A microorganism, or microbe,, ''mikros'', "small") and ''organism'' from the el, ὀργανισμός, ''organismós'', "organism"). It is usually written as a single word but is sometimes hyphenated (''micro-organism''), especially in olde ...
s, including microscopy methods, Coulter counter, Mass Spectrometry (for estimating cell mass), and Cell Culture methods which form and grow colonies of bacteria.
The existing security in dairy products is given by the microbiological quality of the same, which ensures consumption from the point of view of health.
The analysis of the quality of raw milk is a common practice in the dairy industry and aims to control the quality of the samples and the material introduced into the processing plant, culminating in a mass-consumption to ensure quality standards.
Sample preparation
It is important first, to homogenize milk, heating it in a
water
Water (chemical formula ) is an inorganic, transparent, tasteless, odorless, and nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living organisms (in which it acts as a ...
bath at 40 °C for somatic cells that float to the surface along with the fat. The laboratory apparatus must be clean but not necessarily
sterile
Sterile or sterility may refer to:
*Asepsis, a state of being free from biological contaminants
* Sterile (archaeology), a sediment deposit which contains no evidence of human activity
*Sterilization (microbiology), any process that eliminates or ...
, since the method is based on cell count and
asepsis
Asepsis is the state of being free from disease-causing micro-organisms (such as pathogenic bacteria, viruses, pathogenic fungi, and parasites). There are two categories of asepsis: medical and surgical. The modern day notion of asepsis is deriv ...
is not accurate. If later it is going to make detailed microbiological analyzes on the same sample, then it is necessary to be obtained and manipulated with sterile material.
After this process, the sample is transported to the
laboratory
A laboratory (; ; colloquially lab) is a facility that provides controlled conditions in which scientific or technological research, experiments, and measurement may be performed. Laboratory services are provided in a variety of settings: physicia ...
in a 4 °C conservative container. It can be preserved in these conditions for 24 hours.
For sampling there are two basic conditions to consider:
The first one is to represent the total volume of milk from which it was removed, and the second condition involves to be stored and transported at the correct
temperature
Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer.
Thermometers are calibrated in various temperature scales that historically have relied o ...
so that they see their unmodified source properties, prior to analysis in the laboratory. In case of delay in completion of the analysis a preservative that not alter the subsequent analytical result should be added to the milk.
Application of the technique
Be made extended and 0.01 mL of 1 cm2 on fat-free slides (which are cleaned with xylene).
After allowing to dry, it is colored and performs counting. For this, the
average
In ordinary language, an average is a single number taken as representative of a list of numbers, usually the sum of the numbers divided by how many numbers are in the list (the arithmetic mean). For example, the average of the numbers 2, 3, 4, 7, ...
of existing cells is performed in the field of the microscope, dividing total somatic cells from microscopic factor (MF) which corresponds to the number of fields in one inch, i.e. 100 mm, obtaining in this way the number of somatic cells per milliliter of
milk
Milk is a white liquid food produced by the mammary glands of mammals. It is the primary source of nutrition for young mammals (including breastfed human infants) before they are able to digestion, digest solid food. Immune factors and immune ...
.
[http://www.vet.unicen.edu.ar/html/Areas/Inspeccion y Tecnologia de los Alimentos/documentos/2012/Guia_TP_ITA_2012-1.pdf]
;Microscopic Factor Calculation
;Getting the Average:
See also
Somatic cell count
A somatic cell count (SCC) is a cell count of somatic cells in a fluid specimen, usually milk. In dairying, the SCC is an indicator of the quality of milk—specifically, its low likeliness to contain harmful bacteria, and thus its high food sa ...
References
{{reflist
Microbiology
Milk
Food analysis