Inversion rate of sucrose

If you cook that syrup too long it will invert all the sucrose .The rate of inversion can best be followed by polarimetruc readings of the syrup at various stage of cooking but at low pH and high temperatures you will have no sucrose crystalsleft. You will not be able to monitor its inversion rate experimentally..I had cooked starch gummies and the most important part is to consider ,is minimize sugar inversion so that the product will solidify in the molding line.
Therefore we add the acid last, btw I am.using open pan batch cooking and you never acidify a gummy syrup during at the start of the batch cooking to prevent total inversion. It might be okay with extra fast scraped surface cooking where cooking time is done very short time.
Therefore your question is academic but of less significant practical importance in real starch gummy candy manufacture.

Really good answer Roy. Thank you.

In fact this question is about Turkish Delight ( Lokum).

My friend said me that; she sent a producer's delight to a lab to analyse invert sugars content and the lab result says 50 % percentage of total sugar is invert sugars ( glucose + fructose + maltose ).

But the producer says we do not use any invert sugar for delight production.

So we wonder invert sugars content is a result of inversion or producer is lying :slight_smile:

The mistake was they might acidify the syrup at the start of cooking so that's the reason of high inversion rate of sucrose.. Just think of it, heating sucrose and citric acid at above 80C ,the sucrose is totally inverted within few minutes..
Another thing prolonged cooking at an acidic environment due possibly to high glucose content which is acidic will also create severe sugar inversion that your confection will not solidify anymore.

@Roy said in question #5440:

totally inverted within few minutes

Hım,

i did not know this. I thought 50 % inversion is not possible in that conditions.

So , is there a way to sure they used glucose syrup/similar one in production or sucrose was inverted.

Can we detect this?

If they did not use any glucose syrup and rely only from acidification then they should cook fast with modern cookers not old fashioned open pan cooking.
The recipe that you posted will surely lead to high sugar inversion, so its inevitable they have product failure.
BTW, is the recipe you posted the real one or an imaginary one.Most starch gummy used sucrose glucose as sugars ,and even with such conditions cooking should not be slow as it will promote high sugar inversion.
The sugar citric acid solution I mentioned was low pH so rapid sugar inversion occurs.Its similar to preparing invert syrup where at very low acidity sucrose is inverted within 30 minutes.

@Roy said in question #5440:

The recipe that you posted will surely lead to high sugar inversion, so its inevitable they have product failure

Thank you again Roy.

If i get new news i will inform :wink:

Maybe we can detect source of invert sugars in lab. For example if source of glucose is corn starch, we can learn the truth. :face_with_monocle:

Glucose syrup is acidic, regardless of origin .So that's the primary cause of sugar inversion during prolonged cooking.If it's the one used with sucrose.
BTW, are the putting salt also during cooking?

ok. i mean that;

producer says i never use glucose so if i detect corn origin glucose, this mean they use it.

@Roy said in question #5440:

BTW, are the putting salt also during cooking?

no salt. for some type products they add aroma.

I was asking it as salt or NaCl will dissociate into Sodium and chloride ions ; The latter will generate hydrochloric acid on cooking acidifying the syrup hence causing more sugar inversion.
Now to minimize sugar inversion in their simple recipe, they can replace part of the citric acid with buffered lactic acid and cook it according to their standard system.If they are not amenable to adding other ingredients then further reduction of citric acid content might help in reducing sugar inversion rate..

@Roy said in question #5440:

The latter will generate hydrochloric acid on cooking acidifying the syrup hence causing more sugar inversion.

good point. i got it. :+1:

All valuable points as suggested by @Roy,
It was interesting to know about Lokum, a turkish delight, looks more harder (texture) than our usual gummies though.
- For usual gummy preparation glucose syrup is what is used
-yes, lactic acid salts are applied
- Checking brix during the process helps
-speed of gelling is another area to take care
Great topic of discussion @ufukayyildiz, thanks

Hi Ufuk,
As far as i understand from the conversations, your main concern is to find out if the glucose is coming from sucrose inversion or corn syrup which added to the formulation. The best way to understand this is to measure stable carbon isotope ratio (be aware that some source of starches such as wheat and rice have similar isotope ratio with beet sucrose). But before this, i may recommend to measure fructose ratio by a chromatographic method. If the fructose ratio is much lower compared to glucose, then you can say a starch hydrolyzed was added to the formulation.
On the other hand, in my opinion there must be a well balance between sucrose and invert sugar (or glucose syrup) in Turkish delight as it is expected to be soft and smooth. If the sucrose ratio is higher than normal, a crystalline/sandy structure appears. In contrast if the simple sugar content is higher, stickiness could be observed. This textural phenomenon could be overcome by increasing the rate of starch or other thickeners in the absenece of sucrose.

Thank you Mr. Durmaz. Great explanation. :slightly_smiling_face:

@gokhan.durmaz said in question #5440:

As far as i understand from the conversations, your main concern is to find out if the glucose is coming from sucrose inversion or corn syrup which added to the formulation.

@gokhan.durmaz said in question #5440:

The best way to understand this is to measure stable carbon isotope ratio (be aware that some source of starches such as wheat and rice have similar isotope ratio with beet sucrose).

@gokhan.durmaz said in question #5440:

But before this, i may recommend to measure fructose ratio by a chromatographic method. If the fructose ratio is much lower compared to glucose, then you can say a starch hydrolyzed was added to the formulation.

I will check this.

Gorkan Its speculative what you stated there
There is no glucose added to the recipe.
The recipe is so simple, just sucrose, water, starch and minute amount of citric acid..Any glucose (or dextrose) and fructose is only generated from acid inversion of sucrose which is broken down to glucose and fructose and its in constant proportion..It can't be generated from.starch hydrolysis as the syrup is only cooked at normal atmospheric pressure( whereas standard glucose syrup is acid hydrolyzed under pressure. )
If you increase the starch in the recipe you are altering the texture and end product quality, the lokum will not be soft and smooth anymore but too chewy.

@Roy said in question #5440:

The recipe that you posted will surely lead to high sugar inversion,

An update.

My friend sent a Turkish delight ( lokum ) sample which contains only sucrose for analysing of invert sugars.

Results are really interesting: 2/3 of total sugar is invert sugar. glucose/fructose ratio is almost 1:1

No Maltose.

This confirms the fact that the inversion products are just fructose and glucose and remain in constant proportions regardless of the degree of inversion which varies with time if the pH remain constant in the slightly acid status..

Definitely @Roy, you were right at your first post. :wink: