To make a bacterial culture you will need an incubator – fermenter. There are a number of these which you can buy, such as –
Davis & Waddell:
With this fermenter you can set the temperature & the time.
The containers can be supported by 3 coins.
You can make your own using a Chilly Bin (Eski):
Lamp Fermenter:
You will need a chilly bin.
Bolt a lamp holder (screw thread) onto a plastic lid (marmite jar). Screw the lid onto a block of wood. Drill power cable hole into the side of the lid & near the corner of the chilly bin, just above the bottom.
A 12W CFL bulb may do.
Incubator:
You will need a chilly bin, plus – heating pad, controller, plastic box, power cable, bolts.
Racks are useful – I made mine from aluminium. You could make a wooden frame. The plastic containers need to be above the bottom of the bin, so hot air can circulate.
Heat Distribution:
Without a container support in the D & W Fermenter, bottom heating will distribute heat by convection and the temperature variation would be minimal. When the milk sets, convection stops, & conduction through the bottom occurs, so the bottom of the milk will be hotter than the top.
If the container is supported so that there is a gap underneath, hot air will circullate & the temperature will be more even.
Bacteria to Culture:
Milk Cultures:
Lactobacillus reuteri – DSM 17938 and ATCC PTA 6475 strains)
Lactobacillus gasseri – BNR17 strain
Bacillus coagulans – GBI30,6086 strain
Lactobacillus casei – Shirota strain
Kefir – several bacteria & yeasts
Bean/Lentil Cultures:
Bacillus subtilis – natto strain
Capsules containing the first 3 bacteria can be bought from iHerb.
The Shirota bacteria is found in Yakult bought from your supermarket.
Kefir – you wil find this at your supermarket – preferably not containing yeast. In New Zealand, “The Collective” brand is ideal.
Natto – best to buy the powder from China through eBay – 1 packet contains 10x1g sachets. You only need 0.08 g per batch, thus about 120 batches per packet.
Temperatures Needed:
If you search on the internet, you will find some variation. I have taken into account what Dr. Davis suggests & research papers that I have seen.
L. reuteri: 38 C
L. gasserei: 43 C
B. coagulans: 45 – 48 C
L. casei: 38 C
B. subtilis: 38 C
“The Collective” Kefir: 2 batches – 30 C & 38 C
I found temperatures for all 13 bacteria & 2 different temperature batches covers all 13.
Note: You can keep on reculturing the first 4 bacteria. However, if there is a mixture of bacteria, some may dominate with reculturing. After, say, the 2nd batch, you could make Kefir ice cubes to be used as future starters.
Natto is best not reculturing.
Prebiotics: To increase the “food” for the milk cultures you add a prebiotic.
I use potato starch; tapioca is another – yet to be tried.
2T per litre of milk.
Typical Milk Culture Method:
I buy 2 litres of Protein + milk, which is low fat & higher protein.
1. Rinse a large pot with cold water (don’t dry) & heat milk to 90 C- stirring now & then may help – moderate heat.
Keep at about 90 C for about 10 min.