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Explain a wet and dry process for the production of casein products in
the dairy industry
Level
4
Credits
32
Purpose
People credited with this unit standard are able to explain: the composition of
whole milk for manufacturing and how this influences casein manufacture;
the principles of whole milk separation and pasteurisation and their
influences on casein and whey processing; the methods of precipitation of
casein and whey proteins from skim milk; the principles and methods used in
the manufacture of lactic acid casein; the principles and methods used in the
manufacture of mineral acid casein as compared to lactic acid casein
manufacture; the principles and methods used in the manufacture of rennet
casein as compared to acid casein manufacture; and the analysis and
grading of casein and reasons why casein may be out of specification.
Subfield
Dairy Manufacturing
Domain
Dairy Technology
Status
Registered
Status date
5 July 1999
Date version published
17 July 2009
Planned review date
31 December 2014
Entry information
Recommended: Unit 764, Explain a separation and
standardisation process in the dairy industry, or
demonstrate equivalent knowledge and skills.
Accreditation
Evaluation of documentation and visit by NZQA and
industry.
Standard setting body (SSB)
Primary Industry Training Organisation
Accreditation and Moderation Action Plan (AMAP) reference
0022
This AMAP can be accessed at http://www.nzqa.govt.nz/framework/search/index.do.
Special notes
None.
 New Zealand Qualifications Authority 2016
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Elements and performance criteria
Element 1
Explain the composition of whole milk for manufacturing and how this influences casein
manufacture.
Performance criteria
1.1
The composition of whole milk for manufacturing is explained in terms of typical
composition, seasonal variations, and factors affecting composition.
1.2
Components of whole milk for manufacturing are explained in terms of their
form of solution or dispersion, their molecular building blocks, and their physical
state and stability.
Range
fat, lactose, caseins, whey proteins, minerals.
1.3
The composition of whole milk for manufacturing is explained in terms of trends
in the casein to fat ratio that occur during the season.
1.4
The casein fraction of milk is explained in terms of its physical micelle structure,
destabilisation and precipitation by acid and enzyme, and dissolving of acid
casein by alkali.
Element 2
Explain the principles of whole milk separation and pasteurisation and their influences on
casein and whey processing.
Performance criteria
2.1
The principles of whole milk separation are explained in terms of skimming
efficiencies and influences on the fat content of the resultant casein and whey
and their resultant properties.
2.2
The principles of pasteurisation are explained in terms of market requirements,
influences on the microbiological flora, and control of lactic acid starter
incubation.
 New Zealand Qualifications Authority 2016
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Element 3
Explain the methods of precipitation of casein and whey proteins from skim milk.
Performance criteria
3.1
Methods of precipitation of casein and whey proteins from skim milk are
explained in terms of acid precipitation at the isolelectric point of casein,
proteolytic enzyme precipitation at neutral pH, and the use of heat and alkali
treatment for precipitation of both casein and whey proteins together.
Range
3.2
lactic acid casein, mineral acid casein, rennet casein, total milk
protein, coprecipitates.
Methods of precipitation of casein and whey proteins from skim milk are
explained in terms of the resultant solubility of the precipitates in sodium
hydroxide.
Element 4
Explain the principles and methods used in the manufacture of lactic acid casein.
Performance criteria
4.1
The principles of lactic acid starter selection and addition are explained in terms
of requirements for control of acid development and setting times.
Range
strain compatibility, phage resistance, consistency of acid
production, inoculum method, inoculum concentration.
4.2
The principles of casein coagulation are explained in terms of requirements for
control and adjustment of pH to achieve optimum curd strength and structure
prior to cooking.
4.3
The principles of casein cooking are explained in terms of requirements for
control of casein particle agglomeration, syneresis, and the production of firm
casein granules.
4.4
Methods used for casein cooking are explained in terms of differences in capital
and operating costs and potential beneficial or detrimental effects on the casein
and whey, the benefits of low velocity cooking, and the cooking
time/temperature relationship.
Range
4.5
direct steam injection, indirect cooking, combination cooking.
The principles of acidulation of whey and curd are explained in terms of
requirements for control and achievement of granular, free-draining curd, and a
consistent liquid/solid ratio on exit.
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4.6
The principles of dewheying are explained in terms of the requirements for
separation of curd from whey, advantages of mechanical separation compared
to inclined stationary screens, and requirements for minimisation of casein fines
losses.
4.7
The principles of casein curd washing are explained in terms of requirements
for removal of impurities from casein curd, control of the microflora of casein,
conditioning of the curd prior to final dewatering, and advantages and
disadvantages of the three types of washing equipment used in New Zealand.
Range
4.8
wash water temperatures, wash water quality, wash water pH,
alkalinity and hardness, in-line curd milling, prevention and
minimisation of foam.
The principles of casein curd dewatering are explained in terms of the three
principal methods used for dewatering, reasons for dewatering, and the
variables which affect the ease with which casein curd releases its moisture
during dewatering.
Range
initial precipitation pH, starter type, cooking technique, dewheying
technique, casein washing temperature, final wash temperature,
wash water pH.
4.9
The principles of casein drying are explained in terms of the economic
achievement of moisture specifications, the design characteristics of vibrating
fluid bed and pneumatic-conveying driers, the drying characteristics of casein,
and methods of drier control to meet casein moisture specifications.
4.10
The principles of cooling and tempering of casein are explained in terms of the
practical reasons for cooling the dry casein and the need to equilibrate moisture
content both within and between curd particles.
Range
4.11
The principles of grinding and sieving of casein are explained in terms of the
relation between grinding and sieving, the main commercial particle size
specifications, the relation between mesh size and particle size, factors
influencing milling efficiency, and common methods and configurations for
sieving.
Range
4.12
sweating, browning reactions, stickiness, plasticising.
gap between rollers, casein temperature, moisture content, hot
wash temperature, gas content of particles, foreign matter.
The principles of casein blending are explained in terms of methods for
achieving batch uniformity.
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Element 5
Explain the principles and methods used in the manufacture of mineral acid casein as
compared to lactic acid casein manufacture.
Performance criteria
5.1
The principles of acidification and precipitation of mineral acid casein are
explained in terms of the acid/heat process and requirements for achieving
complete precipitation, curd uniformity, low fines in the whey, minimum curd
breakdown during washing, and non-sticky curd in the hot wash and during
drying.
Range
5.2
pH of precipitation, acid concentration, dilution of acid, storage of
acid, temperature for mixing of acid and milk, equipment for mixing
of acid and milk, direct versus indirect cooking, cooking
temperature, cooking residence time, acidulation.
Dewheying, washing, dewatering, drying, and dry processing of mineral acid
casein are explained in terms of differences as compared to the manufacture of
lactic acid casein.
Range
throughput, foaming, casein flavour.
Element 6
Explain the principles and methods used in the manufacture of rennet casein as compared
to acid casein manufacture.
Performance criteria
6.1
Rennet coagulation of milk is explained in terms of kappa casein peptide bond
specificity and reaction rates for the enzymic and clotting stages.
6.2
Rennet coagulation of milk is explained in terms of factors affecting rennet
activity.
Range
6.3
Rennet coagulation of milk is explained in terms of the advantages and
disadvantages of the ‘cold set’ and ‘hot set’ methods of rennet setting.
Range
6.4
casein concentration, enzyme concentration, temperature, pH,
calcium ion concentration, heat treatment of the milk, disruption of
gel formation, rennet addition.
processing flexibility, rennet utilisation, silo flushing and cleaning,
microbial growth, whey clarity, energy savings.
The cooking of rennet casein is explained in terms of requirements and
techniques employed to achieve good rennet curd formation properties as
compared to those used for acid casein curd formation.
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Element 7
Explain the analysis and grading of casein and reasons why casein may be out of
specification.
Performance criteria
7.1
The analysis and grading of casein is explained in terms of the basis of grading
specifications, testing methods and testing frequencies, and common reasons
why the casein may be out of specification.
Range
analyses and grading may include but are not limited to – moisture
content and homogeneity, protein, fat, acidity, pH, lactose, ash,
solubility, colour, particle size, purity, Aerobic Plate Count (APC),
coliforms, E.coli, thermophiles, staphylococci, yeasts and moulds,
bacterial spores, trace elements, pesticides, inhibitory substances,
phosphatase, nitrates and nitrites, bulk density, sediment and
discoloration, appearance, flavour and odour, functional tests.
Evidence is required for a minimum of six analyses and grading
specifications.
Please note
Providers must be accredited by NZQA, or an inter-institutional body with delegated
authority for quality assurance, before they can report credits from assessment against
unit standards or deliver courses of study leading to that assessment.
Industry Training Organisations must be accredited by NZQA before they can register
credits from assessment against unit standards.
Accredited providers and Industry Training Organisations assessing against unit standards
must engage with the moderation system that applies to those standards.
Accreditation requirements and an outline of the moderation system that applies to this
standard are outlined in the Accreditation and Moderation Action Plan (AMAP). The
AMAP also includes useful information about special requirements for organisations
wishing to develop education and training programmes, such as minimum qualifications for
tutors and assessors, and special resource requirements.
Comments on this unit standard
Please contact the Primary Industry Training Organisation standards@primaryito.ac.nz if
you wish to suggest changes to the content of this unit standard.
 New Zealand Qualifications Authority 2016