In order to promote public education and public safety, equal justice for all, a better informed citizenry, the rule of law, world trade and world peace, this legal document is hereby made available on a noncommercial basis, as it is the right of all humans to know and speak the laws that govern them.
EAS 67:2006
ICS 67.100
EAST AFRICAN COMMUNITY
© EAC 2006
First Edition 2006
i| 1 | Scope | 1 |
| 2 | Normative references | 1 |
| 3 | Definition | 1 |
| 4 | Principal compositional requirements | 1 |
| 5 | Pesticides and antibiotics | 2 |
| 6 | Hygiene | 3 |
| 7 | Rapid platform tests on quality of raw milk | 3 |
| Annex A (normative) Organoleptic test and temperature | 4 | |
| Annex B (normative) Determination of insoluble matter | 5 | |
| Annex C (informative) Determination of pH | 5 | |
| Annex D (normative) Clot-on-boiling (C.O.B.) test | 7 | |
| Annex E (normative) Alcohol test | 8 | |
| Annex F (informative) Alizarin-alcohol test | 9 | |
| Annex G (informative) Ten-minute resazurin test | 10 | |
| Annex H (informative) Half-hour methylene blue reduction (m.b.r.) test | 13 | |
Development of the East African Standards has been necessitated by the need for harmonizing requirements governing quality of products and services in East Africa. It is envisaged that through harmonized standardization, trade barriers which are encountered when goods and services are exchanged within the Community will be removed.
In order to achieve this objective, the Partner States in the Community through their National Bureaux of Standards, have established an East African Standards Committee.
The Committee is composed of representatives of the National Standards Bodies in Partner States, together with the representatives from the private sectors and consumer organizations. Draft East African Standards are circulated to stakeholders through the National Standards Bodies in the Partner States. The comments received are discussed and incorporated before finalization of standards, in accordance with the procedures of the Community.
East African Standards are subject to review, to keep pace with technological advances. Users of the East African Standards are therefore expected to ensure that they always have the latest versions of the standards they are implementing.
© East African Community 2006 — All rights reserved*
East African Community
P O Box 1096
Arusha
Tanzania
Tel: 255 27 2504253/8
Fax: 255-27-2504481/2504255
E-Mail: eac@eachq.org
Web: www.each.org
*© 2006 EAC — All rights of exploitation in any form and by any means reserved worldwide for EAC Partner States’ NSBs.
iiiRaw cow milk — Specification
This East African Standard specifies the quality requirements of raw, normal cow milk.
The following referenced standards are indispensable for the application of this East African Standard. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced standard (including any amendments) applies.
EAS 38, Labelling of prepackaged foods
CAC/RCP 57, Code of hygienic practice for milk and milk products
EAS 68, Milk and milk products — Methods of microbiological examination
EAS 161, Milk and milk products — Sampling — Inspection by attributes — Specification
EAS 162, Milk, cream and evaporated milk — Determination of total solids content (reference method)
EAS 164, Milk — Determination of fat content (Routine method)
EAS 165, Milk and milk products — Inspecting sampling — Inspection by variables
ISO 6785, Milk and milk products — Detection of Salmonella spp.
ISO 10560, Milk and milk products — Detection of Listeria monocytogenes
ISO 11866, Milk and milk products — Enumeration of presumptive Escherichia coli
ISO 13366, Milk ⎯ Enumeration of somatic cells
For the purpose of this East African Standard, milk means the normal, clean and fresh secretions extracted from the udder of a healthy cow, properly fed and kept, but excluding that got during the first seven days after calving.
Milk shall contain not less than 3.25 % milk fat and not less than 8.50 % milk solids not fat. It shall not contain added water, preservatives, or other added substances, nor shall any proportion of a natural constituent be removed.
Density of milk at 20 °C shall be within the range of 1.028 g/ml – 1.036 g/ml
The freezing point depression of milk shall be not less than 0.525 °C and not more than 0.550 °C.
When tested in accordance with the appropriate method in Annexes A to J, milk shall:
1Milk shall conform to the following microbiological limits:
The plate shall be incubated for 48 h at 32 °C. The counts shall be graded as follows:
| Grade | Counts (per ml) |
|---|---|
| I | < 200 000 |
| II | >200 000 — 1 000 000 |
| III | >1 000 000 — 2 000 000 |
The plate shall be incubated for 24 h at 37 °C. The counts shall be graded as follows:
| S/N | Quality | Counts (per ml) |
|---|---|---|
| a) | Very good | 0 – 1000 |
| b) | Good | 1000 – 50000 |
Somatic cell count
Somatic cell count shall not 300 000 per ml when tested in accordance with ISO 13366.
Milk shall conform to the maximum limits of pesticide residues as in Table 1 and Codes standards.
| S/N | Pesticide | Maximum limit (mg/kg) on whole milk basis |
|---|---|---|
| a) | Aldrin and dieldrin (total) | 0.006 |
| b) | Heptachlor and heptachlor-epoxide (total) | 0.006 |
| c) | DDT and its analogues | 0.05 |
| d) | Lindane | 0.01 |
| e) | SHC + HCH | 0.01 |
| f) | Endrin | 0.01 |
When analyzed in accordance with appropriate methods of test milk shall conform to the maximum tolerable residue limits for antibiotics and other veterinary drugs set by the Codex Alimentarius Commission.
Milk shall be produced, processed and handled in accordance with CAC/RCP 57.
See Annexes A to J.
3(normative)
Judging the quality of milk by its physical and sensory characteristics requires considerable skill, which could only be acquired by practice. Organoleptic tests are used in all dairies and an experienced person can pick out bad samples with a high degree of accuracy.
Observe the colour of the milk. If abnormal in colour, it should be held over for subjection to confirmatory tests.
Smell the milk in the container immediately after removing the lid. In case of foul or abnormal smell, hold over the milk for subjection to confirmatory tests.
4(normative)
Sediment test on raw milk reveals the extent to which visible insoluble matter has gained entrance to the milk and the extent to which such material has not been removed from milk by single service strainers.
The Sediment test represents a simple, rapid and quantitative measure of indicating the cleanliness of milk with respect to visible dirt.
Allowa measured quantity of milk to pass through a fixed area of a filter disc and compare the sediment left with the prepared standards.
Take a milk sample from well-stirred cans or vats of milk with the sampling dipper. Measure the quantity used with reasonable accuracy. Filter the milk through a properly adjusted, firm lintine cotton disc (rough side facing milk) held in the sediment tester so that a filtration area of 28 mm is exposed. Compare the sediment disc with the prepared sediment standard discs and record the sediment score.
For the purpose of comparison, it is convenient to use about five prepared standard discs so as to classify the milk with respect to its sediment content in accordance with the specific requirement of the dairy or the milk collection depot. For the former, five discs showing 0.1, 0.2, 0.5, 1.0 and 2.0 mg may suffice. Under rural conditions, discs showing 0.0, 0.5, 2.0, 5.0 and 7.0 mg sediment may be more convenient to start with. In either case, no attempt shall be made to estimate the degree of sediment in milk in more than five classes, for example, Excellent, Good, Fair, Bad and Very Bad. No attempt shall be made to grade as sediment any hair, flies, piece of hay or straw or any large particles of dirt. These shall be reported separately.
The presence of appreciable sediment in unprocessed milk supplies indicates careless or insanitary dairy farm practice. However, the lack of sediment is not always indicative of ideal conditions, since visible Sediment may be readily removed by straining at the dairy farm.
5The pH value or hydrogen ion concentration gives a measure of the true acidity of milk. The relationship between pH and acidity of milk is only approximate. In normal cow milk the pH ranges from 6.6 to 6.8. The value is reduced by the development of acidity. On the other hand, the pH value of milk from a cow suffering from mastitis is alkaline in reaction, the value being over 7.0. The pH test is mainly used for the detection of abnormal mastitis in milk. The pH of milk may be determined rapidly by using the indicator strips.
Indicator paper strips or discs are made by soaking strips of absorbent paper in a suitable indicator and drying them.
A rough estimate of pH is obtained by dipping a strip of the prepared paper in milk and observing the colour. Bromocresol purple (pH range 5.2 to 6.8 colour changes from yellow to purple) and bromothymol blue (pH range 6.0 to 7.6 Colour changes from straw yellow to bluish-green) are commonly used as indicators. Both narrow and wide range ready-made indicator papers are available over the pH range 2.0 to 10.5.
NOTE – Indicator paper strips shall always be kept in closed glass bottles and under dry conditions.
In normal milk the pH is well below 6.9. On an average, cow milk gives a pH of 6.6. Milk of pH over 6.9 should be regarded with suspicion as indication of some diseases of the udder or of late lactation milk.
6(normative)
This is a quick test to determine developed acidity and the suitability of milk for processing.
Transfer 5 ml of the sample to the test-tube and smell. Place the tube in a boiling water-bath and hold for about 5 min, and smell again for any acidic flavour. Remove the tube and rotate it in an almost horizontal position and examine the film of milk or side of the test-tube for any precipitated particles. The formation of clots indicative of a positive test.
The principal features of the boiling test are speed and definiteness of results. Milk either remains unchanged or coagulates. Milk, which gives a positive C.O.B. test, has acidity generally above 0.17 % (as lactic acid) and is not suitable for distribution as liquid milk or for processing.
7(normative)
The alcohol test is used for rapid assessment of stability of milk to processing, particularly for condensing and sterilization.
The alcohol test is useful as an indication of the mineral balance of milk and not as much as an index of developed acidity. The test aids in detecting abnormal milk, such as a colostrum, milk from animals in late lactation, milk from animals suffering from mastitis and which the mineral balance has been disturbed.
Ethyl Alcohol, 68 % by weight or 75 % by volume (density 0.8675 g/ml at 27 °C).
Place 5 ml of milk in a test tube and add an equal quantity of alcohol. Mix the contents of the test tube by inverting several times.
Note any flakes or clots. The presence of a flake or a clot denotes a positive test.
A negative test indicates low acidity and good heat stability of milk sample.
Milk showing positive is not considered suitable for the manufacture of evaporated milk, which has to be sterilized to ensure it’s keeping quality.
8(informative)
This test is similar to the alcohol test and the incorporation of alizarin helps to indicate the approximate percentage of acidity.
Same apparatus as described in E.2.
Alizarin Solution, 0.2 % in ethyl alcohol (6.8 %by weight or 75 % by volume, density 0.867 5 g/ml at 27 °C).
Place 5 ml of milk in a test-tube and add an equal quantity of the alizarin solution. Mix the contents of the test-tube by inverting several times. Note the colour of the mixture and presence of flakes or clots. Also note whether the flakes, if any, are small or large.
The general interpretation of the results is as indicated for the alcohol test (see E.5). For acidity of 0.14 % upwards, the graduation in size of the flakes and colour is approximately as follows:
| Colour | Size of flakes | Approximate acidity (per cent lactic acid) |
|---|---|---|
| Lilac | Up to 0.14 | |
| Pale red | 0.4 to 0.17 | |
| Reddish-brown to brown | Small flakes | 0.17 to 0.20 |
| Brownish-yellow | Large flakes | Over 0.20 |
If acidity has not developed and yet coagulation occurs, it indicates the presence of rennet producing bacteria (sweet curdling). Milk from animals suffering from mastitis is alkaline in reaction and when mixed with alizarin-alcohol solution, violet or purple colour is produced. From the practical point of view, it is of little material difference whether milk clots through the production of acid or the production of rennin by bacteria as in either case it is unstable to heat.
9(informative)
This test provides a rapid measure of the sanitary condition and keeping quality of milk. Resazurin reduction occurs in two stages, the first an irreversible change from the blue resazurin to the pink resorufin and the second a reversible change from the pink resorufin and the second a reversible change from the pink resorufin to the colourless dihyroresorufin. The first stage of reduction or colour change from blue to pink is fairly easily brought about so that the quality of milk is assessed in much shorter time. Taking advantage of the two-stage reduction, several procedures have been proposed for reading the end point of resazurin test.
With fresh milk the observed change is resazurin reduction is due to the bacteria present and the leucocytes content. The reduction brought about by leucocytes, however, diminishes with the age of milk. Reduction can be assumed to be brought by the leucocytes if the colour in the down graded milk sample (for example, milk from animals suffering from mastitis) remains unchanged for a longer time than observed normally.
The test is intended as a platform test for detecting milk of poor keeping quality and shall be carried out on samples collected for bacteriological analysis.
| Overall length | 300 mm |
| External diameter | 7.5 mm to 8.5 mm |
| Graduation | one mark only at 1 ml level |
| Distance of graduation from tips | 140 mm to 180 mm |
| Internal diameter | 2.3 mm to 3.0 mm |
The pipettes shall also be calibrated to deliver 1 ml of water at 27 °C when the contents are blown out with the tip touching the side of the vessel, three seconds allowed for drainage and the accumulated drop then blown out. No pipette should have an error of more than ± 2 %, that is, the amount delivered should be between 0.98 ml and 1.02 ml.
Sterile standard resazurin solution
Prepare 0.05 % (W/V) stock solution by resazurin in glass distilled, sterilized water. Preserve in tightly stoppered amber-coloured bottle in a refrigerator. Prepare a 0.005 % bench solution by diluting with sterile water. It shall be prepared fresh after every 8 h. When actually not in use, keep it in a cool dark place.
NOTE – Resazurin powder shall conform to the following requirements:
Start the test as soon as possible after a group of samples has been taken and at least within 30 min.
Shake the sample container at least 25 times, each shake being an up and down movement with an excursion of about 30 cm, the whole process of shaking not exceeding 12 s. After shaking, take 10 ml for the test in the test tube. Place the tubes in numerical order, with the thumb and fingers of the left hand, taking care not to touch the mouth of the tube. Measure 1 ml of the resazurin solution with a sterile pipette, insert the pipette about half an inch into the mouth of the tube and expel the solution by blowing.
Replace the stopper, by inverting the tube twice in 4 s and return to the rack. When resazurin has been added to a batch of not more than five tubes, place immediately in the water-bath and note the time. The delivery jet of the pipette shall not touch the milk in the tube. Any pipette becoming contaminated shall be immediately discarded. Use a fresh sterile pipette for every group of five samples.
At the end of 10 min and 30 s, remove the tubes from the water-bath and immediately match the colour with the resazurin disc in the comparator, recording the results for the tubes in the right section.
11The comparator and stand are placed on a bench at such a height that the operator is able to look down on the two apertures. The disc is then revolved until the sample is matched and the disc reading noted. When the colour falls between two disc numbers, it shall be recorded as the half value; for example, a reading between 3 and 4 shall be recorded as 3.5.
Tubes giving a reading between 0 and 1, streaky pink or very pale pink are recorded as 0.5.
NOTE It is an advantage for two persons to work in a team when a number of samples are to be taken rapidly, one to take the samples and the other to handle the containers and check the identity of the samples. Similarly, at the time of reading one person to watch the tubes and another to record.
The following precautions are necessary to get consistent results:
The results shall be interpreted as follows:
| Disc reading | Keeping quality |
|---|---|
| 4 or higher | Satisfactory |
| 3.5 to 1 | Doubtful |
| 4 or higher | Unsatisfactory |
(informative)
The length of time taken by milk to decolourise methylene blue is a fairly good measure of its bacterial content and hence its sanitary and keeping quality.
Same as in G.2.
Methylene blue solution
Prepare a standard solution of methylene blue by dissolving one of the good quality methylene blue thiocyanate tablets in 200 ml of cold, sterile, glass-distilled water in a sterile flask. It is preferable to allow the mixture to stand for several hours to ensure complete solution.
Depending on the nature of methylene blue tablets used, sometimes the stock solution is further diluted with 800 ml of sterile glass distilled water A concentration of 1 part of methylene blue thiocyanate in 300 000 parts of milk is used to obtain satisfactory results. The solution shall be stored in a sterile glass-stoppered amber-coloured bottle in a dark place and at no time exposed to light. The solution remains stable in the dark for a considerable time but no stock solution more than two months old shall be used
The amount of methylene blue required for a day’s work shall be poured off from the stock bottle into a suitable glass container. On no account shall the pipette used for transferring the methylene blue solution to the tubes of milk be introduced into the stock bottle. Moreover, if at any time during the filling of the tubes methylene blue solution should become contaminated with milk carried into it by a pipette, which has inadvertently come into contact with the milk, the methylene blue solution shall be immediately discarded and replaced by a fresh stock.
Thoroughly mix the sample of the milk by inverting and shaking the sample bottle as described in Clause G3 and then pour the milk in the test-tube up to the 10 ml mark.
While doing this, remove the stopper or cap of the bottle under aseptic conditions, the pouring lip of the bottle and the mouth of the test-tube being flamed, and then pour the milk rapidly into the tube up to the 10 ml mark. While pouring into the tube, take care to leave one side of the interior unwetted with milk. Add 1 ml of methylene blue solution to the tube from a pipette taking care that the pipette does not come into contact with any of the milk in the tube or with the wet side of the interior of the tube.
If this occurs, discard the pipette immediately. During delivery, hold the tip of the pipette against the dry side of the tube about 1 cm to 2 cm above the level of the milk and expel the methylene blue solution by blowing with the mouth or by means of a jet in the pipette. After the lapse of 3 s, blow out the solution remaining in the tip of the pipette and withdraw the pipette. Close the tube with sterile forceps or by the tips of the fingers on the extreme upper end. On no account shall the fingers come into contact with the mouth of the test-tube or end of the stopper which comes into contact with the test-tube. Invert the tube slowly once or twice so that the whole column of contained air rises above the level of the milk and then within 5 min, place the tube in the water-bath.
13Put up the following control tubes with each batch:
The milk for the control tubes shall consist of a mixture of milk, preferably from several products, so as to have an average fat content and colour. Fit the control tubes at (i) and (ii) with stoppers and immerse for 3 min in boiling water in order to destroy the natural reducing system present in the milk.
Comparison of the experimental tubes with control tube (ii) will show when decolourization begins and comparison with control tube (i) will show when it is complete.
Inspect the tube after 30 min. Regard the milk as decolourized when the whole column of milk is completely decolourized or is completely decolourized up to within 5 mm of the surface. If a trace of colour persists at the bottom of the tube and does not extend upwards for more than 5 mm, it may be ignored. Record the time at which decolourization is observed. Where a tube is found not to be decolourized within 30 min, the sample conforms to the test.
The following precautions shall be taken:
The samples, which show complete decolourization of blue colour on incubation for 30 min or less shall not be suitable for acceptance.
14