Small-ScaleDairy Farming Manual |
Volume 1 |
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What should you know about starter cultures?
What is a starter culture and why use it?
(5-11)
1 A starter culture is a milk product which: - contains lactic acid bacteria - controls the souring of milk. |
What types of starter culture are there?
(12-20)
2 There are many types.
- local conditions - the product you want to make. |
How do you prepare and maintain a starter
culture? (21-36)
3 You need: - clean and disinfected equipment - the correct starter culture and high quality milk - to do the right things at the right time. |
How can you prepare mother cultures for making
cheese and yoghurt? (37-38)
4 By using different starter cultures at different temperatures. |
What is a starter culture?
5 A starter culture is milk which contains lactic aid bacteria. |
6 It changes the milk sugar (lactose) into acid (lactic acid) so that the milk becomes sour (fermented or cultured). |
Why use a starter culture?
7 To control fermentation.
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8 These microorganisms turn your milk sour but you cannot control the fermentation. |
9 Pasteurization kills most of these microorganisms. |
10 By using a commercial starter culture with pasteurized milk, you can control the souring of milk |
11 and make:
- butter - cheese - yoghurt and many other products. |
What types of starter culture are there?
12 There are many types of starter culture and we can group them in different ways. |
Optimum growth temperature
13 Mesophilic cultures grow best at about 30 C. Thermophilic cultures grow best at about 43 C. |
Physical state
- liquids - solid (deep-frozen) - powders (freeze-dried). |
15 Powder cultures are useful because:
- they have good keeping qualities (more than 6 months at -20 C) - you can send them long distances by airmail. |
Pure/mixed
16 Pure cultures have
one species of lactic acid bacteria.
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Type of lactic acid bacteria.
17 Some lactic acid bacteria
produce
only lactic acid.
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Some common lactic acid bacteria
used
in cultures are:
Mesophilic Thermophilic
Note:
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18 When you order, say which
product you want to make.
For example: |
Butter
19 You use a mesophilic culture which produces gas (carbon dioxide) and aromatic compounds (acetin and diacetyl). |
Yoghurt and soft cheese
20 You can use a thermophilic culture. |
How do you prepare a starter culture?
Hygiene
21 Clean, sterilize and rinse with boiling water all utensils before using. |
22 Any dirt or chemicals will change the action of the starter culture. |
Equipment and materials
23 You need:
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24
-pans and glass pots with lids -measuring breaker -thermos flask -thermometer -wooden spoon -place to maintain temperature (e.g. a hay box). |
Preparing the milk
25 Remove the cream from high quality milk by skimming or with a hand separator. |
26 Heat treat the skim milk in a closed pot or jacket vat at 90-95 C for 30-60 minutes. |
27 Cool the milk to the inoculation temperature (see instructions on the starter culture packet.) |
Preparing the culture
28 Defrost the packet 30 minutes before use. Shake the powder to the bottom of the packet. Disinfect the top part of the packet with alcohol before opening. |
29 Add the starter culture to the treated
milk and stir thoroughly (10-15 minutes).
You can also make the culture into a paste first with a little boiled milk. |
Maturing the culture
30 Keep the culture at the correct temperature for 24 hours (see packet) by: -using a hay box or -wrapping in cloth in a cupboard or -using a thermos flask. |
Maintaining the culture
31 If you keep the mother culture for a long time, it gets weaker. |
32 Use the clean measuring breaker to
inoculate treated milk with 0.5% mother culture (5 ml culture to
1 l treated milk):
-daily if you have no refrigerator -weekly if you have one. |
Important points
33 The amount of mother culture for inoculation depends on the storage temperature. Try different amounts until it works well. |
34 Keep the culture in clean glass pots,
not more than half full.
Take the culture from the freezer only when necessary and defrost before use. |
35 The mother culture gets weak after
some time.
Although it costs more, it is safer and better to use new starter culture powder after each period. |
36 If you use milk powder make sure the
water is boiled.
You can improve your raw milk for starter preparation by adding 2-3% skim milk powder. |
How can you prepare mother cultures for making cheese and yoghurt?Starter culture for cheese-making
Starter culture for yoghurt-making
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