Leon the Milkman’s Blog

Quick Casein Test

Posted on April 14th, 2006 by Leon the Milkman.
Categories: Cheese, Dairy Science.

Hi, Cheese People

If you have a automated milk composition analyzer it would be possible to get a quick indication of casein by putting the milk through and then setting it with rennet. Take some of the whey and put it through the analyzer as well. Since the rennet binds the casein, by doing a subtraction of the whey protein from the whole milk, you should get the casein value.

Of course some of the more modern analyzers can do the casein automatically, anyway, but this method should help the other guys out there.

Regards,

Leon the Milkman

0 comments.

New CombiFoss

Posted on April 12th, 2006 by Leon the Milkman.
Categories: Dairy Science.

My CombiFoss

Hi, Milk People

This week I got my new Combifoss system. It will test for milk solids, added water and SCC.

Will tell you later if I could figure it out.

Kind regards,

Leon the Milkman

0 comments.

Define Psychrotrophic bacteria

Posted on April 9th, 2006 by Leon the Milkman.
Categories: Dairy Science.

Hi, Milkfans

These bacteria occur naturally in cold places like the Arctic.

They are important in frozen and refrigerated food where they can cause spoilage - even with the cold chain being maintained.

Examples are mould like Penicillium and bacteria like Pseudomonas, Bacillus and Clostridium.

They are an increasing problem in the dairy industry where the cold chain is maintained for longer periods on raw milk, than ever before in history.

Regards,

Leon the Milkman

0 comments.

Judging Dairy

Posted on April 6th, 2006 by Leon the Milkman.
Categories: Dairy Science.

Leon the Milkman judging some dairy products.

Hi, Milkfans

I was a judge at the National Dairy Championships held by Agri-Expo in the Bellville Civic Centre, near Cape Town today.  Thanks, Agri-Expo, it was fun as usual.

May the best products win!

Kind regards,

Leon the Milkman

P.S. check out this following link if you judge dairy as well.

Judging dairy products

0 comments.

Pseudomonas in Cottage Cheese

Posted on April 5th, 2006 by Leon the Milkman.
Categories: Dairy Science.

Hi, Cheesefans

Got a enquiry recently about why Pseudomonas bacteria love cottage cheese so much.

Well, I think it depends a lot on the flavour.

Seriously Pseudomonas are widely distributed and aerobic.  They tend not to use much carbohydrate ( lactose removed from cottage cheese ) and grow well in protein-rich foods (like cottage cheese) producing slime, pigments and some bad odours. They also prefer a high water activity ( high moisture content) and thus cottage cheese is pretty much ideal. Many are also psychrotrophic ( cold-loving ).

Although optimum temperatures are from 15 degrees Celsius to temperate - thus allowing the temperatures to go so high would speed up their growth exponentially.

Goodday to ya,

Leon the Milkman

0 comments.

Automated Milk Analysis and Calibration

Posted on April 4th, 2006 by Leon the Milkman.
Categories: Dairy Science.

Hi, Milkfans

 When doing any automated milk analysis you must remember that the apparatus is calibrated against a certain referance. It is not wise to test cow’s milk on an apparatus that has been calibrated with goat’s milk or vice versa. This has to do with the different sizes of the fat globules, etc.

This is also the reason that ( I think) that goat’s milk digest easier than cow’s milk. It has nothing to do with goat’s milk not having any lactose - that’s nonsense.

 All for today,

Leon the Milkman

0 comments.

UHT Milk Problems

Posted on April 2nd, 2006 by Leon the Milkman.
Categories: Dairy Science.

Hi, Milkfans

UHT milk translates to “Ultra High Temperature” Milk and is also known as long-life milk.

It is made by pasteurizing at something like 132-150 degrees Celsius for a second up to 15 seconds.

To prevent problems it is important that the milk is not going sour, that it has the right salt balance and that there is not too much serum proteins ( colostrum ) in the milk.

Put into practice you should get an analysis of salts in “normal” milk and what variance is allowed to test the milk against. Also make sure the farmer does not have too many cows calving at the same time to prevent high colostrum in the milk.

It is a good idea to do an Alcohol Test on the milk with an alcohol strength of 72-75% alcohol. This will give a fast and accurate indication of the heat tolerance of the particular milk.

Regards,
Leon the Milkman

0 comments.

Density vs. Specific Gravity of Milk

Posted on April 1st, 2006 by Leon the Milkman.
Categories: Dairy News, Milk, Dairy Science.

By determining the specific gravity (SG) of milk the following information can be obtained.

• An indication of adulteration of milk with added water.
• If the fat percentage is available the solids-non-fat (or total solids content) of the milk can be calculated.

Definition

Specific gravity is the relationship of the mass of a specific volume of a substance to the mass of an equal volume of water at the same temperature.

Density is measured as mass per volume (g/ml) at a specific temperature.

The specific gravity of milk at 20 °C is ± 1.030 and is determined by the relative proportions of fat (SG = 0.93), water (SG = 1.0) and solids-non-fat (SG = 1.614).

Kind regards,
Leon the Milkman

0 comments.

Calorie vs. calorie

Posted on March 20th, 2006 by Leon the Milkman.
Categories: Dairy Science.

Hi, Milkmen and Milkmaidens

Have to do a calorie count for a product label?

Here in South Africa we use kiloJoules and the conversionfactor to get that to Calories is to devide by 4.2.
Thus 100 Cal amount to 420 kJ.

Check this difference though: calorie is the energy it takes to heat one gram of water one degree Celsius, and a Calorie(used in Food Industry) is actually a kiloCalorie(1000 Cal.) that has no relation to a calorie. , but is equal to 4.2 kJ.

Got it all figured,
Leon the Milkman

0 comments.

The case of Psychrotrophic bacteria

Posted on March 18th, 2006 by Leon the Milkman.
Categories: Raw Milk, Dairy Science.

Psychrotrophic bacteria seem to be becoming the newest thorn in the side of the dairy industry. Scary bit is that we are helping them along.
“How?” do you ask?
Because of economic factors the pre-processing time of raw milk has been extended to an average of 4 days. This allows ample time for psychrotrophic, proteolytic bacteria to grow, and form heat stable enzymes. Although the psychrotrophic bacteria are easily killed off by normal pasteurization temperatures, the formed enzymes can survive UHT processes.
This causes multiple problems and we here at Elsenburg Dairy Lab have especially seen those problems on products like cottage cheese and UHT milk, more so over the past few years.
This is a group of bacteria that actually loves the cold chain, as it helps them outwit, outlast and outperform their competition.
Nowadays psychotropic bacteria predominate in raw milk in the cold chain, especially Pseudomonas spp.
So much so that when the same milk is plated out and incubated at 7° C and at 30° C(as in Total Plate Count), the psychotropic growth will overtake the mesophilic growth, causing psychrotrophic counts to be higher than total plate counts.
I don’t think the methods of analysis are of much importance in this article, because there are many, ranging from microbial(determining the bacteria) and biochemical(determining the formed enzyme). Qualitative tests are of no use as we want to be able to enumerate the psychrotrophic bacteria.

The main concern I have is to raise awareness of a fast growing problem, that will only become more so in the future.

Possible solutions are the following:

1) Ask your lab to do a monthly psychrotrophic count on all farmers. This will identify
your high risk milk supply.2) Thermising the milk to 68° C before cooling on the farm. This would have to be done with a plate heat exchanger, but would be economical at this stage, because the milk is already at body temperature(37° C) and the treated milk can run against the incoming milk to heat it and to be cooled down itself. An ice bank would also be needed to finish the cooling process. The thermising process would obviously increase the overall quality of
the milk as well, without influencing heat stability to a large degree.
3) Very rapid cooling on the farm to 2° C, instead of the usual 4° C and keeping it there until processing.
4) Using a pre-cooler at the factory to cool the milk down quickly from the 5-7 °C that it arrives at, to 2 °C.

Kind regards,
Leon the Milkman

0 comments.

Older » « Newer