[foodhackingbase] bacteria :)

Thu Feb 16 20:22:21 CET 2012

Hello Webmind and all,
Nice to hear from you! My answers, at least part's are in the email. I copy also tastebridge, 091 brewmasters and food hacking base so people could answer things which I'm not sure about, I hope you do not mind, however your name is on the hackerspaces.org mailing list so you are basted anyway! :-))

Frantisek Algoldor Apfelbeck

biotechnologist&kvasir and hacker

http://www.frantisekapfelbeck.org

"There is no way to peace, peace is the way." Ghandi

________________________________
 From: webmind <webmind at puscii.nl>
To: Frantisek Apfelbeck <algoldor at yahoo.com> 
Sent: Thursday, February 16, 2012 8:03 AM
Subject: bacteria :)

Hiya,

How's stuffs?

>> I'm great I've finally made it to Japan, I'm now based in Kyushu volunteering on various farms, learning the language and being submerged in the culture. I'm waiting for better weather to move North to help with disaster reliefe effords as I planed before. I'm also planning my summer thinking about going for Thoor camp and another events in USA and returning to SF Bay area for a bit but we will see, it is still in progress. Anyway if you want to know more about my stay in Japan check my blog on the link below, in few words it is great, even better than I  thought!

http://kvaseni.wordpress.com/

I was wondering about some things regarding the yogurth-culture.

1) would it be possible to identify the types of cultures present in the
yogurth?

>> The answer is yes but it depends quite a bit what type of gear do you have. Yogurt by definition is composed from Lactobacillus bulgarius and Streptococcus thermophilus plus sometimes various bifidobacteria, however the culture which you got has quite a nice amount of yeasts because it is originating from kefir and I'm quite pretty sure that I've added a bit of water kefir and kombucha at some certain stage in different countries/continents too so it is quite strong "world street mixie" (just to mention, I've had an accident here with heating my cultures which killed my kombucha, water kefir kind of survived, the "yogurt" which is the same as yours is doing just fine and the liquid was smoking hot when I got to rescue it so it is quite stable culure I would say". Optical microscope will help to see the yeast quite pretty well and gram stain staining techniques would help you a bit with the identification of bacteria, you could say what types of
 bacteria are gram positive and gram negative and based on the shape you could determin some of the groups. How accurate you would be I'm not sure because I've done just a little bit of this style identification but you would need just a basic gear for that like optical microsope, staining equipment etc. I used rather the molecular biology techniques which are based on DNA sequencing and after that running it through the gen databases. This approach would identify the organisms very well but you would need quite decent set up to do it, more or less molecular biology laboratory (could be home made). There is a guy on the 091 brewmasters list (I can not remember his name now) who build himself a lab at home and because I need to talk to him too, I'm sending this email to that discussion list there too, I hope you do not mind. He would be really good person to answer your questions in detail because I'm bit weaker on the identification level, which is a
 shame and has to be improved, I need more knowledge and experience in this field but I'm preparing PhD. project where I'll cover that. However presence of alcohol which you can feel in the taste would suggest that yeasts are present (together with CO2 present) and the acidity would point towards acidic baceria, that would be the most simple identification. 

2) do you in what way (if any) the culture reacts with fats? I'm
wondering what the difference between whole milk and semi-skimmed milk
would be.

>> Based on my taste buds and most of the other people, the yogurt from whole fat milk (or with additional added cream for some "extra calories") is more tasty. You can compare it to the low fat yogurts which you can get in the shops and the greek style yogurt which has around 10% of fat. Generally when you add fat in  various dishes it enhancec the flavor because various compounds disolve in the fats, I think that that is the reason why you can taste them better later on, again if someone has done more reading on this please add your opinion/knowledge. Now how the bacteria and yeast really react with fats on metabolic level that is a good question. You can be sure that some of the microbes will find the way how to metabolise fats because it is happening in tthe nature all the time in English I think it is called "get rancid" and tastewise it is generally not the best thing what can happen, various compounds like ketons and aldehydes forms which are
 neither of nice frangrance or flavor (I'm actually not completely sure how they taste but they smell like s...). However again what would be a specific reaction in this case I'm not sure. Based on my fermenting experience the fat has accumulated at the top of yogurt of kefir where it formed kind of "protective layer" which would get bit yelllow from the beginnng (carotens I guess) or during the time (not sure what would be the reason for calouring probably some dye produced as protective layer by some of the microbes against sun light or just as byproduct). I loved to eat it and it was stable tastewise quite for a while, meaning at least in the matter of days at room temperature, in the fridge I would eat the product for weeks happy how it goes more and more acid. If you shake your full fat yogurt vigorously the fat will get compact and form butter which is nice and tasty with bit of "microbial flavor".

The culture is doing great btw, I'm roughly following the current setup,
which works out nicely:
1: ~ a day on room temperature
2: ~ a day in the fridge
3: consume 3/4th
4: add new milk
5: GOTO 1

>>

>>1: With yogurt and kefir I'm trying to have it at 20-30 C at least for a day or two but if your set up makes your taste buds happy great!

>>3: I'm generally leaving one tenth of the yogurt (well something around 5% (v/v) more often), 3/4ths are safe bet.

>>4: One tip. If you leave the container tightly sealed during the fermentation with just a bit of air in, you will get really nice sparkling product because of the carbon dioxide made by yeasts which are present in the kefir. I really love this sparkling effect, plus the light alcoholic flavor, that is the reason why I prefere the kefir compared to the yogurt and also because the culture is stronger therefore less susceptible to contamintation. Anyway before I forget here is the link to the Tastebridge manual to yogurt making, simple but nice!

https://www.noisebridge.net/wiki/Yoghurt_making_manual_-_short_workshop_form

Ciao!

>> Have a great time and thanks for the email, it made me again think about all the things which I want to know and I'm still wondering "how that could be working?"

>> From Kyushu,

>> Frantisek

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