Leon the Milkman’s Blog

Alizarol Test

Posted on August 17th, 2010 by Leon the Milkman.
Categories: Cows, Dairy Farming, Dairy Science, Milk.

1. ALIZAROL TEST

1.1 OBJECTIVE OF THE ALIZAROL TEST

The Alizarol test, due to its simplicity as well as its suitability to point out  more than one defect of milk is a practical and well-suited procedure to test raw milk for acceptability, either on the farm or from the tanker at the factory.  The main objective of the test is to indicate milk in which an unaccepted level of acidity has developed.

The stability of the protein complex in milk is destabilized by acid and therefore a positive alizarol test is also an indication of the heat stability of milk (i.e. the resistance of the protein complex against the denaturation by heat).  The test is therefore also popular where the heat stability of milk proteins is of importance during processing, e.g. during the production of milk powder or UHT milk.

By adding the pH-indicator alizarine to the solution an indication of whether the milk is abnormally sour or alkaline can be obtained.

1.2 FACTORS AFFECTING THE TEST

1.2.1 Acidity

The presence of lactic acid is the most important cause of a positive alizarol test. At the higher acid level  (lower pH )  the protein suspension in milk  will be less stable with the result that protein flocculation (coagulation) will occur  when acid milk is mixed with alcohol.

Under normal circumstances and if the concentration of the alcohol is 68% (v/v), acidity will influence the test as indicated in Table 1.

TABLE 1                       THE ALIZAROL TEST

1.2.2     Mastitis

Mastitic milk differs from normal milk as regards, amongst others, the protein and mineral composition. These differences cause the casein (protein) to flocculate more readily in mastitic milk.  As the pH of mastitic milk is normally  higher than that of  normal milk the alizarine colour will turn violet if such milk is tested.

1.2.3 Sweet curdling

Certain contaminating bacteria are capable of producing rennin like enzymes, which  increase the viscosity of the milk and even flocculate casein in the absence of acid. This phenomenon is known as sweet curdling. Such milk can be identified by  inoculating aseptically a small quantity there-off   into sterilised milk and incubating the inoculated milk at room temperature for a day or more on which the viscosity of the  milk will increase at the  normal pH of fresh milk.

Large numbers of these bacteria e,g. 800,000 /ml milk was found to create a positive reaction in previously sterilised milk.

1.2.4 Mineral imbalance

Too high or to low a concentration of minerals such as calcium, phosphate and citrate will increase the ease with which casein will flocculate in the presence of alcohol.

This aspect is complex and not well define. It is well known that the addition of very small amounts of Calcium (0.2 ml M/4 Ca-acetate / 25 ml milk = 0.6g / 1 l melk ) and Magnesium (0.1 mlM/4 MgCl₂ / _/25 ml milk = 0.95 g / 1l melk ) will normally result in a positive test while the addition of phosphate and citrate salts may alleviate the situation. In more extreme cases excess phosphate and citrate  may however be the cause of a positive test.

Small variation e.g. 0.01% in the normal Calcium content of milk may influence the test.

It is claimed that in some instances supplementing a cows ration with mono-calcium phosphate e.g. 20 - 40 g /day / cow  may  improve the situation.

If a positive reaction is due to mineral imbalance a very slight souring of the milk, causing a portion of the colloidal fraction of the minerals to become soluble, may result in a negative test.

Heating of alizarol positive milk to 60°C for 30 minutes will cause partial precipitation of Ca₃(PO₄ ) and as result the test may turn negative.

1.2.5       Stage of laction;

The chemical composition of early and late lactation milk differs from that of normal milk

in the sense that it is characterised e,g. by higher levels of albumin, globulin and chloride.

Due to these differences the protein suspension in such milk is usually very

unstable against alcohol

Milk is normally very unstable to alcohol in early lactation, thereafter gradually becoming more stable and remaining at a fairly constant level of stability which is specific for each cow. Towards the end of lactation milks from some cows become more stable but a decrease in stability is more common.

1.2.6.   Other factors that may  cause alizarol positive reactions include;

• Irritation of the udder tisue.
• Infected uterus and vagina
• Aborsion

1.3 PRINCIPLES OF THE TEST

The stability of the protein dispersion in milk is maintained by hydration (combining with water) and by the negative electrical charges on the protein particles. If either of these two factors under goes a change, the proteins will flocculate. Alcohol is a dehydrator and therefore destablises the protein. If the protein is already slightly unstable due to souring of the milk, dehydration with alcohol will lead to the precipitation of the protein in the form of flakes.

1.4     REAGENTS AND APPARATUS:

• Measuring equipment: E.g. 2 - 5ml pippettes, siringes or automatic measuring apparatus for measuring milk and alizarol.

• Test tubes, small containers or other apparatus for mixing milk and alizarol.

• Alizarol-solution: Either 68 % (v/v%) or other specified concentration (see Table 2) of ethanol with alizarin powder dissolved in the alcohol.

Alizarol must be kept in a brown bottle in a cool place.

Either methyl (white spirits ) or ethyl alcohol, standardized with water to specified concentration and containing 0.4g alizarin powder (1.2 - dioxy-anthrquinone - C₁₄H₈O₄, MM 240.22, colour code:  CI 58000, pH-reeks:  11.0 - 13.0).  The pH of the mixture should be neutralized to 6.7 and checked regularly.

TABLE 2              APPLICATION OF DIFFERENT ALIZAROL CONCENTRATIONS

1.5 THE PROCEDURE FOR DETERMINING PROTEIN STABILITY (ALIZAROL TEST)

(i)         Equal volumes e.g. 2 or 5 ml of milk and alizarol of prescribe concentration, e.g. 70%, is mixed in a suitable container e.g. a test tube.  (Equal volumes is critical for the accuracy of the test).

(ii)        Mix carefully by inverting the tube once of twice.

(iii)       Evaluate:                -           degree of flocculation, if any

-           colour change

(iv)      Interpretation

-          If the colour remains light purple and no flocculation occurs, accept the milk.

-          If the colour remains light purple and slight flocculation occurs, confirm acidity/ bacterial activity by performing one or more  of the following tests:

• Clot-on-boiling
• pH and/or titratable acidity
• Resazurin test

-          If the colour turns brownish-pink and flocculation occurs, reject the milk.

-          If the milk has a brownish-pink colour but no flocculation occurs, determine the pH or %TA.  If the results are unacceptable, that is, if they do not fall within the prescribed limits, reject the milk.

-          If the colour of the milk varies from brownish-yellow to yellow, reject the milk.

-          If the colour of the milk is violet but no flocculation occurs, determine the pH or %TA.  If the results are unacceptable, that is, if they do not fall within the prescribed limits, reject the milk.

-          NB!  Take care not to interpret fat granules in cold milk for protein flocculation.

Contact Prime Pharma for the Alizarol Test Kit

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Alizarol Test Kit Video

Posted on August 17th, 2010 by Leon the Milkman.
Categories: Cows, Dairy Farming, Dairy Science, Milk, Milkman.

www.primepharma.co.za

What is good about this alizarol test kit?

• Very small and handy
• only 400 microlitres of alizarol used per test
• Spring-loaded syringe makes sample taking easy
• Flip-cap bottle, so that cap cannot fall into milk or onto floor
• Can be washed and re-used few times to lower cost
  

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Forgot to milk the cows? - won’t happen again!

Posted on May 3rd, 2007 by Leon the Milkman.
Categories: Cows, Dairy News, Milk.

Talk about serious issues!!  According to Reuters an employer in India beheaded one of his workers for not milking his cows.  He should drink more milk - it calms you.

I’m off

Leon the Milkman

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Music for Cows

Posted on November 21st, 2006 by Leon the Milkman.
Categories: Art, Cows.

Hi, Cow Fans

Have a listen to the “Milk Cow Blues”…

Kind regards,

Leon the Milkman

P.S. Remember to drink your milk!

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Guernsey Body Characteristics

Posted on November 20th, 2006 by Leon the Milkman.
Categories: Cows, Milk.

Guernsey

Hi, Cow Fans

Guernsey cows should weigh, when mature, between 1050 and 1250 pounds, and bulls from 1700 to 2000 pounds. Considerable variation in size now exists, however, due partly to the recent admission into the USA, and their registration as Guernseys, of the cattle which for centuries have been raised on the third largest of the Channel Islands, namely, Alderney.  For some reason the mature cattle of Alderney Island are not as large even as the Jersey and fall very far short of matching the ideal Geurnsey. There are many who believe that it was a serious blunder to admit into America these small cattle, especially to admit them in the name of a much larger breed. Many breeders and practical dairy farmers, who have chosen Guernseys over Jerseys, have done so because of the reputed greater size of the former.

The Guernseys naturally carries a little more flesh than the Jersey and is not so sensitve to the cold. To reduce the scale of the animals now is to throw them into the Jersey class in this respect where they will probably be easily equalled as efficient dairy animals by Jerseys of their own size. The color of the Guernsey is orange-yellow and white, in large patches. The shade of the yellow varies from light to a near red. Neither extreme is desirable.

The temperament of the Guernsey is particularly agreeable. She is intelligent, but not so nervous, not so affectionate nor so resentful as the Jersey. Neither is she so indifferent as the “cold blooded” Holstein. Her sunny disposition and easy handling habits have won her many friends. There is an tendency, however, for individuals and families of this breed to lay on fat to readily.

Calves at birth should weigh from sixty to eighty pounds and are inclined to be somewhat delicate. They are not as easily reared as the young of either the Holstein or the Ayrshire breed. Heifers mature rapidly and unless care is taken are liable to begin milking to early for best growth.

Drink your milk.

Kind regards,

Leon the Milkman

2 comments.

Cow Series Audio

Posted on November 19th, 2006 by Leon the Milkman.
Categories: Cows.

Leon the Milkman

0 comments.

Guernsey cows

Posted on November 18th, 2006 by Leon the Milkman.
Categories: Cows.

Hi, Cow Fans

The Guernsey breed of cattle is one of comparative recent recognition, not that animals of the present Guernsey characteristics have not been in existence for a considerable time, but rather that since their qualities and adaptations were so similar to those of the Jersey, the two breeds were, during a considerable part of the last century, considered as one breed and were spoken of a “Alderney” cattle, from the group of Alderney or Channel Islands to which the islands of Jersey and Guernsey belong.

It is sure that some interbreeding took place very early on, but since 1763 the residents of Jersey forbade the introduction of new breeding stock and Guernsey did the same in 1819.  So since then the breeds have been kept pure.  

Considerable differences now exists between the Guernsey and the Jersey.  Professor Low, writing in 1841, seems to consider the cattle from the two islands as essentially one breed, yet goes on to describe those on Guernsey Island as larger and more highly marked with orange yellow skin, and as yielding a somewhat more yellow milk and butter.  More recent investigations strongly support the theory that at some period several hudred years ago animals which were the true descendants of the “spotted cattle” or Simmenthaler, of Switzerland, had been introduced as breeding stock on the Island of Guernsey.  Not only is this supported by the larger size, quieter disposition, and more yellow secretions of the Guernsey, but also from the fact that there are at present animals possessing characteristics similar to the Guernsey and Simmenthaler on either side of the Rhine River. 

Although the Guernseys were taken at an early date to England they were used largely by the nobility, the same as were the Jerseys.

Kind regards,

Leon the Milkman

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Holstein-Friesian 3

Posted on November 11th, 2006 by Leon the Milkman.
Categories: Cows.

Hi, Cow Fans

The land upon which this breed of stock has been pastured for many generations is largely of a low, marshy order; in fact, much of the land is that reclaimed from the ocean by the thrifty Hollanders, who diked across the arm of the sea and literally pumped the water back into the ocean by means of windmills.  The land thus reclaimed is immensely fertile, but, being lower than sea level, continues moist and comparatively cold.  Grass grows luxuriantly.  Upon these moist pastures the cows are pastured in summer.  They are not permitted to roam about, but are tethered out.  This system of feeding and handling is ideal for the production of bodily size and a quiet disposition.  

The colour of the Holstein-Friesian is always black and white.  Very rarely a red and white animal is dropped from pure parents, but is not eligible for registry.  The size is large.  A mature cow should weigh 1300 pounds, and not infrequently individuals attain 1500 and occasionally 1700 pounds.  A mature bull of this breed should weigh between 1800 and 2400 pounds.  The disposition of the Holsteins, as a breed, is very mild, in fact, they are so quiet that they are one of the easiest breeds to handle.  They are greedy feeders and naturally they are not particular in regard to the condition of their feed as are some other breeds.  The calves weigh 90 pounds or more at birth and are easy to raise. 

The Holsteins as a breed may be said to produce the largest quantity of the leanest milk of any breed.  It is thus an excellent producer of drinking milk and not so much preferred for cheese making where higher milk solids are beneficial.  Although the olstein produces more kilograms of fat and protein per lactation, because of the volume it produces, it is still better suited for drinking milk or milk for the manufacture of condensed milk.  This is further impacted by the fact that the Holstein milk has a comparatively higher amount of albumen to casein. 

The smaller fat globules and the low butterfat content as well as the very white butterfat obtained when skimmed of Holstein milk makes it less than ideal for butter manufacturing.  All the above factors makes it probably the cow milk that is most ideal for baby feeding.

Drink you milk!

Leon the Milkman

 

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Holstein-Friesian 2

Posted on November 9th, 2006 by Leon the Milkman.
Categories: Cows.

Hi, Cow Fans

Though the parent stock has been kept pure, many off-shoots and modificationshave taken place in surrounding countries; thus, modified Holland cattle are to be found in various parts of Belgium, Germany and France.  This blood contributed to the development of the early Teeswater cattle, now known as Durham or Shorthorns, as well as having also furnished foundation for much improvement effected of late years in Russia.  This breed is believed also to have been used to some extent in establishing the Ayrshire breed.

Till tomorrow,

Leon the Milkman

p.s. Drink you milk!

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Holstein-Friesian

Posted on November 8th, 2006 by Leon the Milkman.
Categories: Cows.

Friesian being milked [image thanks to www.animationfactory.com]

Hi, Cow Fans

For the next few days we will be discussing the Holstein Cow.

This breed is one of the oldest, of either beef or dairy animals in America.  It had its beginnings in the Netherlands, mainly in the North-East province, Friesland, and is unquestionably the same which made the Hollanders famous throughout the civilized world more than a thousand years ago.  Even back during the flourishing days of the old Roman Empire, large, black and white oxen, and cheese were continually being sent from the regions now known as the Netherlands.  A race of cattle with many of the present characteristics of the Holstein-Friesians doubtless were being maintained practically pure fully 20000 years ago and Holland has remained famous as a dairy centre during the centuries since. 

Till tomorrow,

Leon the Milkman

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