Bacteria are tiny single-celled organisms. You can't see them but they're everywhere. On cows. In milk. On your plant. They're even inside you.
One litre of perfectly good milk will still contain thousands of bacteria. That's normal. The trick is keeping those numbers low enough that they don't land you with a Bactoscan F or a thermoduric grade.
How Bacteria Grow
Bacteria reproduce by splitting in two. So, one becomes two. Two become four. Four becomes eight and so on. Under the rightconditions, they can double every 20 minutes. That's exponential growth and it gets ugly, fast.
Let's say you've got just one bacterium:
After 1 hour: 8 bacteria
After 6 hours: 64
After 9 hours: 512
After 12 hours: 4,096
Now make that starting number more realistic, say 1,000 per ml. After 12 hours, you're at 4 million per ml. That's 10x worse than a Bactoscan F.
You see why it's crucial to not only get onto sorting a dreaded grade if one arises but more importantly, prevent getting one in the first place.
What Makes Them Multiply
Bacteria need the right conditions to grow. Here's what fuels them:
Condition
What it does
Can you control it?
Moisture
Most bugs love dampness
No
Food
Organic matter = dinner
Yes
Temperature
Cold slows growth; heat kills
Yes
pH
Extremes in acid/alkali kill them
Yes
Oxygen
Some need it, some don’t
No
Bottom line: you control the food, the temperature, and the pH. That means you can control the growth with the right detergents, cleaning routines, and hot water systems.
And here's the kicker:
If you've got a grade, you've got bacteria.
So, if a grade hits, you’ve got to find which factor is allowing bacteria to thrive. Then fix it.
Soil: What's Stuck in Your System
There are two types of soil in your plant: mineral and organic.
1. Mineral Soil
Comes from your water (iron, manganese, calcium, silica)
Shows up as dullness, staining, or discolouration
Harmless to milk itself but it makes surfaces rough
Rough surfaces = bacteria paradise
Generally located at the top of the milk line and inside of the vat
2. Organic Soil
This is the real threat. It's made of milk fat and protein - exactly what bacteria love to eat.
Fat deposits feel greasy and slippery
Protein deposits look like a rainbow sheen or brown stain on stainless surfaces
Generally located on vat walls, floors and upper surfaces of receiving cans at the top of the milk line, especially where the wash water is not making contact
Worst of all?
When mineral soil and protein team up, they form milkstone: a tough-as-nails deposit that's hard to shift and dangerous to ignore.