Yogurt Temperatures

[Guest guest]

In the course of doing some research for updates to the Pecanbread

website, the question, which has come up on a number of lists, was asked

about the best temperature for fermenting SCD yogurt.

Here's what I found:

S. Thermophilus and L. Bulgaricus are required for making yogurt. Either

L. Acidophilus or L. Casei or both may also be included. Acidophilus is

found in the Yogourmet starter, which contains a small amount of cow

dairy. L. Casei is found in the Progurt dairy-free starter recommended

for ASD children.

S. Thermophilus (heat-loving bacteria) ferments best at a temperature

of 45°C (113°F)

L. Bulgaricus, ferments best in a range of 40-44°C (104-111.2°F)

L. Acidophilus (acid-loving bacteria), ferments best in a range of

37°C-42°C (98.6-107.6°F)

L. Casei ferments over a wide range of temperature and pH levels, but

prefers a temperature lower than 43°C (109.4°F).

For this reason, it is recommended to ferment SCD yogurt between

38°C-43°C (100-110°F). Please note that your yogurt will not be ruined if

the temperature rises slightly above this range or falls slightly below

it, but the closer to the center of this range that you come, the better

chance the bacteria have of fermenting optimally.

Now, if you're interested in reading more than usual about the various

strains, try this:

A statement has been made on one of the lists that l. casei requires

a lower temperature for fermentation than the other three strains. I

spent quite a bit of time trying to verify the statement that l. casei

likes a lower temperature than the rest of the legal bacteria, and

couldn't find any articles on it, nor have I yet found a definitive

temperature, just the observation that l. casei ferments well in a

wide range of temperatures and pH values..

What I came up with was the following:

http://microbewiki.kenyon.edu/index.php/Streptococcus_thermophilus#Ecology

Streptococcus thermophilus is an essential lactic acid bacterium used

for commercial purposes, which includes the production of milk, cheese,

and other dairy products. This organism is a thermophilic Gram-positive

bacterium with an optimal growth rate at 45 °C. It is also capable of

generating energy, in the form of adenosine triphosphate (ATP), by

aerobic respiration with the presence of oxygen; however, without the

presence of oxygen, it still can produce ATP through fermentation. S.

thermophilus lacks cytochrome, oxidase, and catalase enzymes. It does not

have motility and it does not form spores. Although S. thermophilus is

closely related to other pathogenic streptococci (such as S. pneumoniae

and S. pyogenes), S. thermophilus is classified as a non-pathogenic,

alpha-hemolytic species that is part of the viridians group. The

increasing consumer need for dairy products and booming manufacture of

dairy products ($40 billion industry) led to the investigation and

sequencing of S. thermophilus.

http://microbewiki.kenyon.edu/index.php/Lactobacillus_delbrueckii

(this is l. bulgaricus)

As an inhabitant of fermented dairy products and producers of lactic acid

Lactobacillus delbrueckii, with the exception of L. subsp. delbrueckii,

is the cause of its low acidic environment. The nutritional requirements

are adapted to the bacterium’s environment; as such includes but are not

limited to amino acids, vitamins, carbohydrates and unsaturated fatty

acids (9). L. delbrueckii has an optimal growth temperature of 40-44 °C

under anaerobic conditions(3). Specifically, L. subsp. bulgaricus

has a symbiotic relationship with Streptococcus thermophilus as it

coexists in starter lactic acid bacteria cultures.

http://microbewiki.kenyon.edu/index.php/Lactobacillus_acidophilus

Since then L. acidophilus has been further characterized as a short

Gram-positive rod (2-10µm), is homofermentative and has optimal growth at

temperatures of 37°C-42°C. Of the Lactobacillus species, L. acidophilus

is the most well known and is commercially distributed as a probiotic.

The World Health Organization defines a probiotic as " live

microorganisms which, when administered in adequate amounts, confer a

health benefit on the host " .

http://microbewiki.kenyon.edu/index.php/Lactobacillus_casei

http://www.probiotics-lovethatbug.com/lactobacillus-casei.html

L. casei grows over a wide range of temperature and pH.

http://www.ehow.com/about_5531574_lactobacillus-casei.html

Lactobacillus casei is a species of lactobacillus bacteria. This

specific bacterium is found in the human mouth and intestine. It is a

beneficial microorganism and helps to promote other beneficial bacteria

and prevents the overgrowth of pathogenic bacteria in the human body. In

particular it helps with the growth of beneficial bacteria such as

Lactobacillus acidophilus.

L. casei is considered beneficial for the digestive process for a number

of reasons. Firstly, it has a wide temperature and pH range meaning it

can withstand the acidic environment of the gut. It also promotes L.

acidophilus which produces the enzyme amylase. This enzyme assists your

body in the digestion of carbohydrates, which can help prevent conditions

such as constipation and irritable bowel syndrome, according to a study

by Reading Laboratory in England.

Diarrhea is commonly observed in critically ill children who have been

admitted to hospital for care. According to a 2006 study, there is

increasing evidence that probiotics decrease the incidence of acute

infectious and nosocomial and antibiotic induced diarrhea among children

hospitalized in nonintensive care settings. L. casei has been used safely

and with positive effects for when given to critically ill children

suffering form diarrhea.

http://hrcak.srce.hr/index.php?show=clanak & id_clanak_jezik=31975 & lang=en

For both acidophilus and casei, a temperature 37°C (98.6°F) was more

appropriate than 43°C (110°F). Note that these were the two

temperatures used for an evaluation of bacteria including acidophilus and

casei. It did not say that this was the optimum temperature for either

probiotic, only that they did better at the lower temperature. No mention

was made of testing in between these two temperatures.

—

Marilyn

New

Orleans, Louisiana, USA

Undiagnosed IBS since 1976, SCD since 2001

Darn Good SCD Cook

No Human Children

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