Download miễn phí Đề tài Sanitation in dairy plant
Contents
PREFACE . 5
I. Overview about sanitation in food plant . 6
1. Sanitation . 6
2. Importance of sanitation: . 6
2.1. General food plant: . 6
2.2. Dairy plant: . 8
II. Sanitation in dairy plant . 8
1. Personel: . 8
1.1. Personal hygiene: . 9
1.2. Hand washing: . 10
2. Sanitation agents . 15
2.1. Thermal . 15
2.2. Steam . 15
2.3. Hot water . 15
2.4. Radiation . 16
2.5. Chemical Satizers . 17
2.6. Enzymatic cleaning . 21
3. Equipment . 22
3.1. Mechanical Abrasives . 23
3.2. Water Hoses . 23
3.3. Brushes . 23
3.4. Scrapers, Sponges, and Squeegees . 24
3.5. High-Pressure Water Pumps . 24
3.6. Low-Pressure, High-Temperature Spray Units . 24
3.7. High-Pressure Hot-Water Units . 25
3.8. Steam Guns . 25
3.9. Portable High-Pressure, Low-Volume Cleaning Equipment . 25
4. Sanitation methods . 27
4.1. Regulation and process of cleaning and disinfecting . 27
4.2. Cleaning process in the dairy plant’s areas: . 31
5. Biofilms, formation, developemt, and control . 40
5.1. Introduction . 40
5.2. Bacterial biofilm development . 41
5.3. Detection . 42
5.4. Treatment options . 43
REFERENCES . 46
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cult to cleanareas and to compensate for the natural dilution that may occur because of the presence
of condensation or residual rinse water from cleaning.
Temperature:
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The growth rate of the microorganisms and the death rate due to chemical application
will increase as temperature elevates. A higher temperature generally lowers surface
tension, increases pH, decreases viscosity, and creates other changes that may Giúp
bactericidal action. An exception is the iodophors that vaporize above 50°C. These
chemicals are more aggressive to surfaces, especially elastomers and gasketing materials,
as the temperature rises. Thus, chemical sanitizers should be applied at ambient
temperatures, ideally 21 to 38°C. Generally, the degree of sanitation greatly exceeds the
growth rate of the bacteria, so that the final effect of increasing temperature is to enhance
the rate of destruction of the microorganisms.
Concentration:
Increased sanitizer concentration enhances the rate of destruction of the
microorganisms.
pH:
The activity of antimicrobial agents occurring as different species within a pH range
may be dramatically influenced by relatively small changes in the pH of the medium.
Chlorine and iodine compounds generally decrease in effectiveness with an increase in
pH.
Desired Sanitizer Properties
The ideal sanitizer should have the following properties:
● Microbial destruction properties of uniform, broad-spectrum activity against vegetative
bacteria, yeasts, and molds to produce rapid kill.
● Environmental resistance (effective in the presence of organic matter [soil load],
detergent and soap residues, and water hardness and pH variability)
● Good cleaning properties
● Nontoxic and nonirritating properties
● Water solubility in all proportions
● Acceptability of odor or no odor
● Stability in concentrated and use dilution
● Ease of use
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● Ready availability
● Inexpensive
● Ease of measurement in use solution
A standard chemical sanitizer cannot be effectively utilized for all sanitizing
requirements. The chemical selected as a sanitizer should pass the Chambers test (also
referred to as the sanitizer efficiency test):Sanitizers should produce 99.999% kill of75
million to 125 million Escherichia coli and Staphylococcus aureus within 30 seconds
after application at 20°C.The pH at which the compound is applied can influence the
effectiveness of the sanitizer. Chemical sanitizers are normally divided according to the
agent that kills the microorganisms.
Chemical sanitizers are often used in dairy plant such as:
Chlorine Compounds,
Iodine Compounds,
Bromine Compounds,
NH4
+
,
Acid Sanitizers,
Peroxy Acid Sanitizers,
Acid Anionic Sanitizers,
Hydrogen Peroxide,
Ozone
Ozone, a molecule comprised of three oxygen atoms, is naturally occurring in the
earth’s upper atmosphere. It acts as a powerful and nonselective oxidant and
disinfectant,(which indicates that it will attack any organic material that it contacts) and
may control microbial and chemical hazards. Common by-products of ozonation are
molecular oxygen, acids, aldehydes, and ketones. This sanitizer does not cause a harmful
residue or contaminated flavor.
This sanitizer is a more powerful disinfectant than chlorine. It has been used safely
and effectively in water treatment and is approved in the United States as Generally
Regarded as Safe (GRAS) for treatment of bottled water and has been applied in the food
Industry in Europe during the past. It has a broad spectrum of germicidal activity.
Generally, ozone is a more effective bactericide and virucide than chlorine and chlorine
dioxide. Ozone is being evaluated as a chlorine substitute. Because it oxidizes rapidly, it
poses less environmental impact than some compounds.
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Ozone is expensive, unstable, corrosive, temperature sensitive, very reactive, and
should be generated as needed at the site of application. It is produced commercially
through the incorporation of an ozone generator that uses electricity to generate the gas
and ozone. The ozone is used as a gas or is contacted with water for application. A high
voltage, alternating electric discharge is passed through a gas stream (dry air or oxygen).
To control the electrical discharge and maintain a corona, a dielectric space or discharge
gap is formed using a dielectric material such as ceramic or glass. A grounded electrode
that is usually produced from stainless steel acts as a boundary to the discharge space.
The most common shape for ozone generators is a cylinder, which is the most space-
efficient, economic form .Care must be taken to ventilate the equipment properly as
released ozone can be irritating to workers. Ozone is very unstable at a high as well as at
a low pH. Ozone is most effective at a pH range of 6.0 to 8.5. As water temperature
increases, the solubility of ozone decreases. It dissipates almost immediately at 40°C.
Ozone is a broad-spectrum germicide which is effective against food pathogens, yeasts,
and molds, and viruses and protozoa. It has been used to sanitize dairy equipment and to
disinfect water, including pools, spas, and cooling towers and for algae control in water
and wastewater treatment plants. It is not tolerant of organic soil. The probable mode of
action of ozone is through the attack on the cell membrane, rupturing and killing the cell.
Another application is to release gaseous ozone in cold storage rooms to control molds
and eliminate ethylene, which can accelerate ripening in fruits and vegetables. Ozone is
more stable in the gas phase and in an aqueous phase.
The use of ozone presents safety issues. It is a powerful irritant to the respiratory
tract and a cellular poison that interferes with the ability of lungs to fight infectious
agents. Ozone, as chlorine dioxide, has been found to produce brominated organic
compounds that are alleged potential carcinogens. Furthermore, there is a high capital
cost associated with the use of ozone including the need for generators at point of use as
well as the energy costs to operate them. Also, ozone is corrosive to soft metals and mild
steel as well as rubber and some plastics.
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Table 1: Specific Areas or Conditions where Particular Sanitizers are Recommended
2.6. Enzymatic cleaning
It is known that monocomponent enzymes can be used for biofilm removal. The
heterogenicity of the biofilm matrix limits the potential of these enzymes for use in
effective cleaning. The proteinase samples, e.g. chemotrypsin were shown to be effective
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in reducing and inactivating pure-culture biofilms, but when milk residues were present
no effect of the proteinases could be observed. The different enzymatic cleaning
procedures tested were also shown to be ineffective in inhibiting growth and metabolic
activities of bacterial strains isolated from dairies. Based on the varying results obtained
for removal and inactivation of microbes on surfaces by enzyme preparates, one
possibility could therefore be to combine various types of enzymes to attain efficient
cleaning. The use of enzymes is also limited due to the lack of techniques for quantitative
evaluation of the enzymatic effects and the accessibility of the different enzymatic
activities. The results showed that the resazurin-based fluorometric assay tested during
that part of the project performed at the Faculty of Veterinary Medicine at the University
of Helsinki can be used for estimating the enzymatic activities on process surfaces. This
method can be recommended especially when a rapid, high-throughput capacity system is
needed (Mikkola, 1999; Augustin, 2000).
Table 2: Optimal Cleaning Guides for Dairy Processing Equipment
3. Equipment
Cleaning is generally accomplished by manual labor with basic supplies and
equipment or by the use of mechanized equipment that applies the cleaning medium
(usually water),cleaning compound, and sanitizer. The cleaning crew should be provided
with the tools and equipment needed to accomplish the cleanup with minimal effort and
time. Storage space should be provided for chemicals, tools, and portable equipment.
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3.1. Mechanical Abrasives
Although abrasives such as steel, wool, and copper chore balls, can effectively
remove soil when manual labor is used, these cleaning aids should not be used on any
surface that has direct contact with food. Small pieces of these scouring pads may
become embedded in the constructi...