I'm sincerely interested in understanding more about Dr. Goldberg's scientific methods for determining the actual carb content of finished yogurt. If anyone has a copy of the book ... could you please post the details, ie .. did he use chemical reagents, electrical impedance (that's how a home glucose meter works) or electron microscopy??? Also, what are his comments on residual glucose and galactose sugars in the finished yogurt?

I'm trying to get my hands on a copy of either the previous GO-diet book or the newer "Four Corners" edition, but it's harder to find than chicken's teeth I prefer not to order from outside of Canada, but I'll keep looking.

I love yogurt, and have it often (plain balkan style with active cultures and 5% fat). But I account for 80% of the carbs listed on the label, not 4g per cup .


Doreen

This might be a great way of eating. I can't believe, though, that yogurt would eat up part of the carbs it contains, at least not without making the stuff taste even worse than it already does because there would be nothing left but very sour, sour curdled milk.

hi there,

Yes, much of the research I've done (and others, such as Dr. Richard Bernstein, author of "Dr. Bernstein's Diabetes Solution", Dr. Elaine Gottschall, author of "Breaking the Vicious Cycle" about bowel disease and the Specific Carbohydrate Diet, and also the Atkins official center) .. indicates that finished yogurt still contains a significant amount of digestible carbohydrates. Please have a look at my previous post about this ... The Truth about carbs in YOGURT.


As I stated above, I really love yogurt .. but I also really want to have the FACTS, based on sound science and proof.




Doreen

Doreen, there has been mention of a brand here called "Harvey Fresh" which claims to be 100% lactose-Free Yoghurt and is 3.5g per 100g which is about half what full cream milk is here (4%)

I understand they explain theirs is lower carb because they add something called a lactase enzyme to further convert the remaining lactose into simpler sugars which in turn lowers the carb count.

Now this might be true - if the lactose is all digested and if the glucose part is all the converted to lactic acid (2 big ifs) then that would explain their result of about half the normal carb count. Mind you if they have had it independently tested (another if ) who are we to argue. Of course that gets you down to how much faith you can have in the information on any label, but that is another subject again

Have you heard of additional "lactase enzymes" being used in this way?

Malcolm

Yet another diet that makes saturated fats an enemy.

What is the difference to South Beach? If someone asks to give a short version of south Beach, I say exactly that except I call the pharmafoods nuts and low fat dairy. How long ago was the Go diet published? I am just wondering what makes the SOuth Beach book a bestseller and something at least similar a couple of years ago something rarely heard of.

Hmm, I don't think so ..

I've ordered the book, but may be a few weeks getting here. In the meantime .. The program is not anti-saturated fat. They do focus on monounsaturates and encourage reduction in POLYunsaturates. Lean meats. poultry with skin, whole eggs, full fat dairy are allowed and encouraged. It's not like South Beach, which restricts saturated fat.

The program encourages 50% of fat from monos. If you think about it, that's biologically appropriate -- Most animal fat - beef, pork, poultry - is approx. 50% monos, and 45% saturates. .. here are some sample food lists


Doreen

Thanks for posting this! The GO diet was one of my favorites and I will definately look into purchasing the new book just for curiosity sake. I've actually been doing a more basic LC plan since December and have found it worked wonders for me whereas on the GO diet although I liked it I didn't lose nearly as well. But I'm still interested to see how they revised it, if they revised the plan at all.

Tam

I don't understand how this forum works. But here goes. I'm also interested in the science behind the carbs in yogurt.

Re the methods: This is I think what Dr. Goldberg used:

Enzymic methods for the measurement of lactose are well known and are generally based on the hydrolysis of lactose to D-galactose and D-glucose with β-galactosidase followed by determination of either D-galactose or D-glucose. In the International Dairy Federation Methods(79B:1991) for the measurement of lactose in “dried milk, dried ice-mixes & processed cheese”, details are given for deproteinisation of samples, hydrolysis of lactose with β-galactosidase and measurement of either released D-galactose or D-glucose


http://216.239.51.104/search?q=cach...ctosidase&hl=en

See above for full details.

The important thing to understand is that the bacteria take up the lactose whole. Then the enzymes inside the bacteria split the lactose into glucose and galactose and metabolize them into lactic acid. Glucose and galactose can be interconverted in many species. How much conversion goes on probably depends on the species of bacterium, which varies a lot from brand to bran.

See the Danon site for a picture of this: http://www.danonevitapole.com/extra...ile/DWN02US.pdf

The carb content of the yogurt *will* vary depending on what you start with and how long you ferment it. Commercial yogurt sits around a long time before you buy it, and even if it is kept cool, some fermentation continues. Commercial yogurt usually has milk solids added and hence starts off with more lactose.

This URL gives lactose values as low as 4.

http://www.nationaldairycouncil.org...cts/table10.pdf

I would assume that the rest of the lactose had been taken up by the bacteria, hydrolyzed by beta-galactosidase into glucose and galactose, and then further metabolized (broken down). Note that this is different from Lactaid milk, in which you use the same (or a similar) enzyme to break the lactose into glucose and galactose, but there are no bacteria to break those sugars down into lactic acid so the carb count doesn't change.

Yogurt has a very low GI. I think it's about 14, with a glucose load of 2, so I think the lower numbers are reasonable.

Gritchen, I won't pretend to understand all the science behind this, but the Danon site you refer to states this;

"During milk fermentation, about 20-30% of the lactose in milk is
fermented by lactic acid bacteria through different pathways (
Figure 1). Yogurt bacteria are homofermentative, producing one
major end product, in this case lactic acid, which accounts for
greater than 95% of the fermentation products."

Is this any different from the results reported by Doreen in the discussion thread on the so called yoghurt exception?

Cheers,

Malcolm

Commercial yogurt makers stop fermentation at a certain pH because they don't want it too sour. Then they add pectin or cornstarch to thicken it.

They measure the carbs at the end of the manufacturing process, not when the stuff hits the store shelves.

I'm not an expert on yogurt culture. I just wanted to give some leads to those who want to pursue this. But if you want strict carb control, you're better off making your own.

Yes well I do make my own most of the time, but that still leaves open the question of what percentage of the lactose is converted to simple sugars which from a low carb diet point of view will still 'count', and how much is turned into lactic acid in which case it doesn't count as carbohydrate any more.

In this part of the world, one of the things often added to commercial yoghurt to make it richer are "non fat milks solids" which raise the initial lactose count by an unspecified amount so that you are left with little choice than to accept the manufacturers final carbohydrate count on the label.

Cheers,

Malcolm

hello Gretchen, welcome!

Interesting post .. especially the reference links, which are the exact ones I used (among others) when doing my own research into the matter.

Um, you seem to be missing the point of that Megazyme booklet ... The description is for determining the lactose content only, not the total carbohydrate content. Lactose content is determined indirectly by measuring the free galactose ... note that the article states:

"The measurement of lactose as D-galactose liberated is more generally reliable than measurement as D-glucose liberated because preparations generally contain more free D-glucose than free D-galactose."

As I noted in my essay The Truth about carbs in YOGURT, finished yogurt, whether commercial or home-made, contains residual lactose + glucose + galactose sugars. These all must be taken into account when considering the total carbohydrate content, not just lactose alone.

The galactose content in yogurt is a known health concern for some people who lack the liver enzyme which converts galactose into glucose (glycogen). Galactose can build up in the bloodstream leading to a condition known as galactosemia ... which is associated with impaired brain development in children, and eye damage/cataracts in adults.

~~~~~~~~~~~~

This is incorrect. Yogurt's bacteria secrete the lactase enzyme (beta-galactosidase) which hydrolyses the lactose ... ie, splits it into glucose and galactose. Only glucose is utilised by the bacteria to be converted to lactic acid. The galactose remains unconverted. From the US Dairy Export Council:

"About 20 to 30% of the lactose in the yogurt base is broken down to glucose and galactose, and the glucose is converted to lactic acid during yogurt fermentation..."

The reason is because galactose requires an alkaline environment in order to be fermented into lactic acid. If you refer to the Metazyme booklet which you linked to ... right below the bit you quoted about "Enzymic methods for the measurement of lactose are well known" ... you'll see in the chemical equation where:

The β-D-galactose is then oxidised .....at pH 8.6

Yogurt is hardly alkaline with pH approx. 4.2. Even liquid milk starts at a pH of approx. 6.5. To achieve an alkaline pH, sodium hydroxide (NaOH) must be added before galactose will ferment (oxidise) to lactic acid.

~~~~~~~~~~~~
Yes, the lactose content may go as low as 4 g per cup (depending on amount of fermentation or sourness), but there is still the free glucose and galactose to consider as part of the total carbohydrate content in yogurt.

~~~~~~~~~~~~~~
Yogurt is made very successfully from Lactaid or similar lactose-reduced milks, using the same bacteria as for regular yogurt. Since the step of splitting the lactose into its two monosaccharide components has already taken place, Lactaid-type milk actually ferments much more quickly than regular milk because the glucose is readily available. You can read more about this here.





Doreen

[QUOTE=doreen T]
Um, you seem to be missing the point of that Megazyme booklet ... The description is for determining the lactose content only, not the total carbohydrate content.

Correct. As I said, I'm not an expert on this. But I would assume the sugar content of milk is well known, and that lactose is the main sugar. Hence disappearance of lactose should equate to disappearance of significant carbohydrate.

Because bacterial beta-galactosidase is contained within the bacteria, it wouldn't break down lactose outside the bacteria. So if you spun out the bacteria and measured the lactose in the supernatant, you'd have an indication of how much lactose the bacteria had eaten.

Yes, there might be some lactose and glucose and galactose and numerous other sugars that are involved in living processes within the bacteria. If the bacteria remain whole until they reach the colon, this wouldn't be significant. Even if they don't, this might not be significant. I suspect it's never been studied.

The protein we eat as well as the glycerine part of fats can also be converted to carbohydrate and we generally ignore these when calculating carbs in LC diets, although people with diabetes who are injecting insulin do take them into account.

Another possibility is that some of the bacteria in the yogurt are dying and breaking down, releasing beta-galactosidase into the whey. In this case they could create glucose and galactose from remaining lactose. But the galactose or glucose (whichever was measured in the assay) would be included in the results.

>The galactose content in yogurt is a known health concern for some people who lack the liver enzyme which converts galactose into glucose (glycogen).

Yes. There are many carbohydrate diseases. And people with this particular disease shouldn't eat lactose. This doesn't mean that healthy people shouldn't eat carbohydrates. Glucose is not synonymous with glycogen. Glycogen is a polymer made up of many glucose units. It's human starch.

>Only glucose is utilised by the bacteria to be converted to lactic acid. The galactose remains unconverted.

Glucose and galactose are interconverted in most species via UDP-glucose and UDP-galactose. In some bacteria, the presence of galactose in the medium induces the formation of an enzyme called "galactozymase," which ferments galactose.

>Yes, the lactose content may go as low as 4 g per cup (depending on amount of fermentation or sourness), but there is still the free glucose and galactose to consider as part of the total carbohydrate content in yogurt.

Because the assay for lactose involves measuring the glucose and/or galactose, these will be measured by the assay.

>Yogurt is made very successfully from Lactaid or similar lactose-reduced milks, using the same bacteria as for regular yogurt. Since the step of splitting the lactose into its two monosaccharide components has already taken place, Lactaid-type milk actually ferments much more quickly than regular milk because the glucose is readily available.

And what is the point of paying extra for Lactaid? I'm not particularly interested in the speed with which my yogurt ferments. I usually leave it overnight.

As I noted, I'm not an expert in this, and I don't want to debate it ad infinitum. I just wanted to provide some information. For those who are able, perhaps eating yogurt and measuring the resulting blood sugar levels would be the best indication of how the particular yogurt you eats is affecting you.

This is why I don't eat commercial yogurt