Yoghurt - Product of value to customers and business tables

Yoghurt is a very perishable product and needs a cold chain to maintain its quality.

This is a very nutritious product and a complete food.

Production of quality yoghurt needs;

1. Selection of good quality raw milk

2. Pasteurization of the raw milk

3. Cooling of the pasteurized milk to the inoculation temperatures conducive to the bacteria for fermentation (stature culture)

4. Inoculation - Putting or adding the culture

5. Incubation -This is the period set for the fermentation process to  complete

6. Stirring -This is the breaking of  the curd to a thick liquid mixture

7. Refrigeration -It is lowering the temperatures to  FRIDGE CONDITION

8. Procedure

   • Select the good quality milk- Milk which has passed the platform tests and any other i.e. it had no adulteration, no foul smell, has low acidity level, has its right colour ,no residues of veterinary drugs etc.

• Pasteurize the raw milk - Milk is heated indirectly in order to destroy the pathogenic bacteria  and being careful  not to destroy the heat sensitive vitamins which require slow heat inducement.

• It is usually recommended if yoghurt has to be added sugar it should be done during the milk pasteurization so that sugar is added to the milk at the rate of 4-5 percent of the milk volume to be used. If there are any impurities in milk; the pasteurization will address the issue and this will avoid contamination of the product as compared  to when the sugar is added after the product is ready (during consumption)

Where there are no pasteurizer make sure the heat is not transferred directly to the container containing milk meant to be  pasteurized but let water be a heating media( meaning heat water then the heat from the water heats the milk)

• Cooling - Cooling is lowering the milk temperature to the temperatures required for inoculation  favorable for the lactic bacteria. For the case of Yoghurt we cool the pasteurized milk up to 40-45 degrees centigrade  which is favorable for the fermenting bacteria for yoghurt

• Inoculation - This is putting or introduction  of the starture culture bacteria  into the pasteurized milk selected for yoghurt production .After the introduction the milk is stirred for about 5 minutes for the even distribution of the bacteria in the the whole batch ready for the next stage of process.

• Incubation -  This is the period set for the fermentation process to  complete. It take 4-6 hours if there is an incubator where the temperatures remain constant as set and it takes 8-12 hours if the incubation is done at room temperatures .At the end of these said hours  there is a curd ( thick uniform body)formation.

• Stirring - This is the breaking of  the curd to a thick liquid mixture. This done by stirring.

• Refrigeration -It is lowering the temperatures to  FRIDGE CONDITION. This is a must for yoghurt. The process of fermentation does not stop causing an increase in acidity  until its addressed by cooling product. Once left to proceed the multiplication activity will make the yoghurt to finally taste bitter.

• Packaging - Packaging is optional as this depends on the final destiny of the product

• -After pasteurization cool  the milk rapidly to avoid any chances of bacteria contamination

Cool to 40-45 o C as these are temperatures favorable for fermenting bacteria for yoghurt

• -Inoculate -Add culture -make sure its not expired

• -Incubate - Give the inoculated milk time for fermentation process

  Usually yoghurt ferments between 4-6 hours if its placed  in an incubator(controlled temperatures)  and  takes up to 8 to 12 hours if the temperatures are not controlled like a room of 27 o C to 30 o C

• -Stir - Breaking of the curd

This is done until there are no lumps observed

• -Put or add colour a flavour -Optional

Avoid putting any other colour and flavour that is not of the dairy product. These are from plant origin/extracts (natural)

• -Refrigerator your final product -A must in yoghurt

Bacterial activity of fermentation in yoghurt  continues if yoghurt is not cooled  and this can lead to bitter yoghurt if the bacterial activity is not stopped .

Refrigerated yoghurt`s aroma and flavour is more profound if its cooled.

Yoghurt processing is a simple way of fermenting well pasteurized milk .The pasteurized milk is cultured with  the Yoghurt fermenting micro-organisms and incubated for the given period.

This course needs a person who can understand and willing to follow instructions on how to employ the technology.

Yoghurt is a nutritious  milk product profitable to people of all ages. Its a complete food  rich in carbohydrates, proteins, fats, vitamins, minerals, fiber and water. It is important that everyone consumes these seven nutrients on a daily basis to help them build their bodies and maintain their health.

Its demand is high therefore  quality is key as we engage in the processing.

We have the responsibility of ensuring  safety of the public and  meeting the customers expectations; ensuring our product to be to the standards set by the governments.

Quality product is key for  growing /maintaining market space.

Things to note in processing

1. Processing yoghurt product can be done with or without machines. Its okay once the technology required is rightly captured and followed. Processing is easy and can be done in a home set-up.

2. Its required that the personnel handling milk should be medically certified.

3. The environment should be clean with fresh air and without any foul smells.

4. The animal being milked should be healthy/milk from a healthy animal .

5. The equipment should be of the recommended container for milk handling.

6. The detergents  should be of light lather and mild smell so as not to introduce any form of contamination.

7. Milk should not have any traces of veterinary drugs or off flavor e.g. from feeds, and taints

8. Follow carefully the procedures for milk pasteurization, cooling , inoculation , incubation and finally evaluation of the final

   product

9. Milk  handling for the purpose of processing should be done hygienically to avoid contamination and that includes;- the time of production, transportation, storage and processing.

10. Once poor quality raw material  is processed the final product will also be poor. Garbage IN garbage OUT.

Adulteration by water addition in  milk is a prohibited culture (though this is done by unfaithful traders for a the purpose of gaining  much from their investment).

Note:

To maintain standard of the product; - Sample testing of the output against specifications is paramount in maintaining  the quality required .

How to segregate good quality milk from poor quality

Separation of milk depending on its quality is done by testing the milk before reception

These are tests which are simple, quick  to perform and give quick results

a. Organoleptic test

b. Alcohol test

c. Phosphatase test

d. Lactometer test

e. Sediment test

f. Clot on boiling test

Organoleptic

In this test, a tester uses the five senses to do a judgement on the milk sample  to check if its fit for the intended use.

Check for normal  smell, colour, and consistency .

If it does not comply its either rejected, or segregated / separated for further tests.

Alcohol test

This test is for checking for acidity level.

Though milk has a natural acidity there is a limit required and the excess of it renders the milk not to be  fit for any further processing i.e. heat treatment Acidity increases due to presence of mastitis bacteria, developed acidity or colostrum milk ( colostrum milk has high amounts of proteins which are unstable when  heated)

Procedure for alcohol test

Take small same amounts e.g. 2ml of milk and ethanol; Ratio 1:1 (Diluted alcohol of about 70 percent concentration) then mix

If the milk acidity is higher than expected; a precipitation or clots is noted .

If the acidity is normal no changes will be noted in the mixture.

Phosphatase test

Alkaline Phosphatase is an enzyme which is naturally present in milk, but is destroyed at the pasteurization temperature. Alkaline Phosphatase test is used to indicate whether milk has been adequately pasteurized or whether it has been contaminated with raw milk after pasteurization.

Procedure

In the sample picked for testing deep the testing strip.

A colour change is immediately realized if the milk is unpasteurized of re-contaminated with raw milk from blue to green.

No changes occurs  or is realized when the milk is adequately pasteurized and no recontamination

LACTOMETER TEST

How to check water by use of a Lactometer

Milk adulteration and the knowledge of the tests is necessary. The nutritional value of milk to human health needs no introduction at the same time; it is alarming that many vendors are adulterating it with water, detergents, caustic soda, starch, formalin, urea, ammonium sulphate, sodium carbonate which have harmful effect on the human health.

The greed for money has pushed them to the extent of producing synthetic milk which has no nutritional content. “Adulteration” is a legal term meaning that a milk product fails to meet federal or state standards. Adulteration is an addition of another substance to milk in order to increase the quantity of the milk in raw form or prepared form, results in the loss of actual quality of milk. Milk adulterated is mainly done for financial gain but it can also be adulterated due to unhygienic conditions such as processing, packaging, transportation, distribution etc.

Water is the most common adulterant used which decreases nutritional value of milk and lowers the quality too.

Lactometer checks for any added water in the milk. This is an instrument used to determine the richness of milk.  It works on the principle of specific gravity of milk. It consists of a Test-Tube and a Meter Bulb.

Using this instrument is very simple;

1. Put some milk in the test-tube.

2. Dip the meter bulb in it, the bulb going in first. You will notice that the meter bulb floats. The reading on the meter indicates how pure/impure your milk is.

3. The deeper the bulb sinks, the more dilute/impure the milk.

4. If the reading is at the red mark, it shows that the milk is rich and pure and visa versa.

Milk is one of the most important ingredients for children’s overall development, it is essential for adult health as well.

Milk is also widely used in food item like desserts, baking, tea and coffee etc.

The most common reason for milk adulteration is;

-  The difference between demand and supply of milk. In order to meet the demand, the suppliers usually adulterate the milk and increase the quantity.

- The adulterants like  glucose add to the thickness and viscosity of the milk while starch prevents curdling of milk.

- Due to lack of hygiene in milk handling and packaging, detergents (used during cleaning operations) are not washed properly and find their way into the milk. 

- Other contaminants like starch, glucose, these adulterants are used to increase the thickness and viscosity of the milk --Formalin are used as adulterants as well  to preserve milk for a longer period.

- Water turned out to be the most common adulterant in milk. It reduces the nutritional value of milk. If contaminated (with pesticides, heavy metals), water poses a health risk to consumers

Sediment test

This is a test to check the amount of physical dirt in milk (sediments)

A clothing or sieve with fine openings  is used to pass the milk through .The amount of dirt that will remain on top will determine the level of dirt that was in the milk hence its acceptability.

Clot on boiling test

This test also tests for increased acidity in milk

Procedure

Heat the sample and if the acidity is low the milk sample will boil. If the acidity is high there will be noted a precipitation or clots.