Mastering Dr William Davis’s homemade yogurt made with the probiotic ‘Lactobacillus Reuteri’ has been no easy feat. We empathise with your failed attempts because we’ve had plenty along the way too. No one really wants to eat thin and separated yogurt, do they? As we always do, the Luvele kitchen has continued to experiment and we have now discovered a key step that makes all the difference.
Before we go on, if you’re new to all this, here is Dr William Davis sharing about the significant benefits of L reuteri. It’s hard to deny it’s worth getting into you!
Dr Davis created his method using half and half milk, which is a full-fat milk commonly available in America (in the UK and Europe, it’s known as ‘half cream’). Half and half is a blend of equal parts whole milk and light cream. It averages 10-12% fat, which is more than regular milk but less than regular cream (and it can’t be whipped).
Half and half isn’t available in Australia, so, in our first L. reuteri yogurt post, we did our best to recreate half and half by combining full cream milk and full fat pure cream. We produced a unique, yogurt-like end product but had our suspicions that it wasn’t quite right. Our customers confirmed that our homemade half and half looked different to yogurt made with store bought half and half milk.
After further experimentation, the Luvele test kitchen has found a method that results in a creamy, consistent yogurt that tastes great. And it just requires one extra, but significant, step that has traditionally been used in yogurt making.
Traditional yogurt making practises have always heated the milk first. Heating and holding milk at 82° C (180° F) for 20 minutes (or longer) denatures the milk proteins so that they bind and set together. In addition to this, the little bit of evaporation and concentration that occurs during the extended heating helps to improve the texture.
Including this step before adding the probiotic bacteria and prebiotic powder made a profound difference to the structure and texture of our L. reuteri yogurt. Without heating, our first attempts with homemade half and half milk produced fragile and thin yogurt with lots of separated whey and the cream content set on top. A similar separation of fat and liquid happened in our first experiment below.
In our aim to replicate half and half milk, we considered non-whipping ‘pouring cream’ (with a lower fat content), a better addition to milk. With our pouring cream and milk mixture we set out to make 2 batches of L. reuteri yogurt; one with heated milk and one with milk straight from the fridge (our control batch). Both samples were otherwise treated identically; they had the same amount of probiotic culture, prebiotic powder and were incubated for the same length of time.
The results speak for themselves. The jar on the left was heated and held for 20 minutes and produced consistent, firm, thick set yogurt. Perfect yogurt. The jar on the right was not heated - the end product curdled, expanded in the jar and produced an unusual amount of whey separation at the bottom.
Because the process of heating made such a vast improvement, we wondered if cream was required at all? In our next experiment, we decided to exclude cream from the mix and heat 100% ‘full cream milk’ only. (In Australia ‘Full Cream Milk’ is about 3.5% fat, and in the USA it’s known as 'whole milk' which is about 3.25% fat). We used unhomogenised organic milk. Again, we made 2 batches. One with the recommended 10 tablets and one with only 3 tablets. Both samples were otherwise treated identically; they were heated and held for 20 minutes, had the same amount of prebiotic powder and were incubated for the same length of time. Both samples produced equally thick yogurt. The only noticeable difference was the jar with 3 tablets formed a pocket of whey separation. We do not consider this a concern as the whey can be poured out leaving thicker yogurt curd in the jar.
If store-bought, half and half milk is available in your area, we recommend you follow Dr Davis original method that does not heat the milk. From our feedback, this method produces reliable results. Where half and half milk is not available, we recommend, heating ‘full cream milk’ (or ‘whole milk’ in America and Canada). The method is below. It is necessary to purchase organic milk to guarantee no antibiotics are present.
Dr Davis’s original method specified 10 probiotic (BioGaia Gastrus) tablets be used to inoculate milk into yogurt. If you’re familiar with BioGaia Gastrus probiotic tablets, you’ll know how expensive they are! We have experimented using fewer tablets and are pleased to say that we had significant results with only 3 tablets. Because our experiments produced thick textured, tart tasting yogurt we are confident that bacterial fermentation occurred however, without clinical trials on the yogurt, accurate CFU counts are unknown.
A portion of your first jar of L. reuteri yogurt – the ‘mother batch’ - can then be used to re-inoculate your next jar of L.reuteri yogurt. This means that when preparing your next batch, you simply replace the 3 crushed tablets with a third a cup of L. reuteri yogurt. It is also possible to freeze a portion of yogurt or whey and use at a later time.
To ensure the L reuteri strains stay pure and uncontaminated, we recommend re-inoculation not occur indefinitely. To ensure the yogurt stays abundant with the L. reuteri strains, and not a breeding ground for other, unwanted bacteria, we recommend starting a fresh mother batch after 4-5 re-inoculations. If you notice any significant changes to the texture, smell or taste of your yogurt, you should do this sooner.
To keep the strains in abundance, some customers suggest adding 1 crushed probiotic tablet with the third of a cup L. reuteri yogurt or whey.
Dr Davis’s recommends L. reuteri yogurt ferment for 30 to 36 hours. Our research into developing the best yogurt makers on the market together with our extensive experience making yogurt has us confident that a 24-hour incubation is sufficient. The thickness of this yogurt is evidence enough.
Because L.Reuteri bacteria are not traditional yogurt culturing strains we have chosen to add the following disclaimers:
1 Litre of whole milk
2 tablespoons pure organic inulin powder (or prebiotic powder of your choice)
3 tablets of BioGaia Gastrus, crushed or 1/3 cup of L.reuteri yogurt or whey from a previous batch
Before you begin it is important to sterilise the Luvele yogurt making glass jar, lid and any utensils you use, in boiling hot water. The danger of not sterilising is that other bacteria may overpower your culture and affect the quality of your yogurt.
1. Pour the milk into a large clean saucepan.
2. Place the saucepan on the stove top and heat the milk to 82° C (180° F) Use a thermometer for an accurate reading.
3. Hold the milk at this temperature for 20 – 30 minutes. It can be a challenge to hold the milk at a high temperature for so long. We recommend using a double boiler pot filled with boiling water. Don’t get too caught up on the precise temperature. If the milk accidently boils briefly, don’t panic – reduce the heat and continue.
4. Remove from the stove
5. Cover the milk & let cool to below 42° C (107° F). You can actively cool it by filling a sink, or bowl with cold water and setting the pot of heated milk in the cold water. It is fine if the milk cools down below 42° or even goes cold, it just mustn't be too hot. Temperatures above 43° C will kill the L. reuteri strains. As the milk cools, a layer of skin will form on the top. There is no harm leaving it in. It does not produce lumpy yogurt.
6. Pour 1/3 cup of preheated and cooled milk into a small ceramic bowl.
7. Pour the remaining milk into the yogurt making glass jar.
8. Add the inulin powder to the small bowl of milk and mix to form a slurry. Note: It will have a gluey consistency and may not incorporate.
9. Add the probiotic starter - one of the below methods:
a) Crush 3 BioGaia Gastrus probiotic tablets into a fine powder using a mortar and pestle, or other hard object on a clean, dry surface. Add the crushed probiotic powder to the milk & inulin slurry and mix in. The inulin will cause an inconsistent texture in the slurry. Don't worry. Pour the mixture into the jar of milk and whisk to incorporate.
b) Add 1/3 cup of L. reuteri yogurt or whey from a previous batch (frozen and defrosted may be used) to the slurry and mix in. Pour the slurry into the jar with the milk and whisk to incorporate.
10. Put the lid firmly on the yogurt making jar and place into the yogurt maker. Pour water slowly into the base. The water must not be filled over the ‘tall line’ indicated on the inside wall of the maker. Place the cover lid on top.
11. The milk is now ready to begin fermentation. Use the digital control panel to set the temperature to 36°C and the time to 24-hours and then press ‘confirm’ to begin incubation.
12. After 24 hours the timer will go off.
13. Condensation will have collected under the cover lid during fermentation. Take care removing it and allow the water to drip into the water bath, instead of your bench.
14. Switch the yogurt maker off and remove the yogurt jar. Straight from the maker the L. reuteri yogurt will be warm. Do not stir the yogurt while it is warm or else is will not set in a perfect mass.
15. Depending on the milk you used, your yogurt may have a thin layer of cream on top. Bonus, this is delicious!
16. Place the yogurt in the fridge for at least 6 hours to set then enjoy.
Don’t forget to reserve a third of a cup of yogurt or whey for your next batch of yogurt!