Dear Abdolazim Hasseli please see this useful link entitled "The structure of sucrose in the crystal and in solution". The article is available as public full text on RG:

Chapter The structure of sucrose in the crystal and in solution

Thank you Frank T. Edelmann

I am still waiting for an answer...

Dear Abdolazim Hasseli here is another potentially useful article which might help answering your question. The paper is entitled "Role of water in sucrose crystallization".

Article Role of water in sucrose crystallization1

Please find attached a pdf of this article.

Excellent reference Frank T. Edelmann ;

Abdolazim Hasseli , the water content per sugar molecule is the hyration number n as described in the paper provided by Frank. n= 5. (See page 338, at the beginning of section 3.)

The reference is Bressan, C. & Mathlouthi, M. (1994), Zuckerind, 119, 652 -658

The title is: Thermodynamic activity of water and sucrose and the stability of crystalline sugar

Thank you Frank T. Edelmann

Thank you Gerhard Martens ,

Can I conclude that there are water molecules in the crystalline structure of every sugar crystal?

If so, how these water molecules are coordinated with the sugar molecules?

Can you address me any image of sugar crystal in which water molecules are also being shown?

Dear Abdolazim Hasseli ,

I think so, unless there have been applied some procedures to reduce or remove the water.

But you should directly ask*) Mohamed Mathlouthi, one of the authors of the reference mentioned above. He is member of RG, but unfortunatlely this paper is not listed in his publication list ( Mohamed Mathlouthi ).

You may ask him for that paper and for a crystal sketch via RG messenger. He seems to be that top specialist about sugar properties.

Good luck....

Please give feedback when Mohamed Mathlouthi has (hopefully) answered.

*) That is the way how researgate should really work...

Dear Abdolazim and Gerhard - Please find attached another very interesting paper reporting the crystal structure determination of sucrose. The article is entitled "Sucrose, a Convenient Test Crystal for Absolute Structures" and it is freely available as public full text on the general internet. Interestingly, there is no mention of any water of crystallization in the crystal structure. Thus I assume that sucrose crystallizes from water or water / ethanol mixtures as pure compound. When you search the internet for pictures of the "crystal structure of sucrose" you also find pictures like the attached one without any water of crystallization:

https://crystallography365.wordpress.com/2014/01/12/sweet-crystallography-the-crystal-structure-of-sucrose/

See this link

The Sweet Science of Candymaking                

By Tom Husband 

Dear all,

with respect to 'crystal water'

please have a look at the third sentence in:

https://www.frusano.com/front_content.php?idart=82&changelang=2

"Every commercially available dextrose contains up to 10% crystal water."

Dear Gerhard Martens yes, but glucose (dextrose) is a different sugar molecule than sucrose. According to the attached paper, glucose can for a well-defined monohydrate.

Dear all,

Sugars are hydrated in aqueous solutions. The average number of hydration water molecules is around 2 to 3 molecules for Glucose and Fructose and 5 for Sucrose. We have published a paper showing the relationship between between hydration numbers and water activity and density. This paper " Relationships between hydration number, water activity and density of aqueous sugar solutions by Adem Gharsallaoui et al. _ Food Chem.106(2008) 1443-1453" has been added as a public Full Text in RG.

In the crystalline state not all sugars are hydrated. Sucrose for example crystallizes as anhydrous crystal. However, during the steps preceding the crysta nucleation and growth, water plays a major role. The disassociation of hydration water to allow sucrose molecules assemble in the crystal proves to be one of the highest energy barrier in the hurdle race of crystal formation. This is explained in the paper " Role of water in sucrose crystallization by M. Mathlouthi and J. Genotelle, Carbohydr. Polymers, 37(1998) 335-342." This paper is also added as public Full Text in RG.

Other sugars like Glucose crystallize as monohydrate. Trehalose crystallizes as dihydrate. The comparison of disaccharides crystallization depends on their interactions with water and their structure features. This was published in a paper entitled " Water–disaccharides interactions in saturated solution and the crystallisation conditions by Adem Gharsallaoui et al. Food Chem. 106(2008) 1329-1339. This paper is also added as public Full Text in RG

Many thanks Mohamed Mathlouthi

for that short but nevertheless comprehensive insight in the hydration water issues of sugar.

So let me summarize:

a) in aqueous solution the sucrose molecules are coupled in average to 5 water molecules per sucrose molecule,

b) but in crystalline form sucrose is anhydrous (no crystal water).

So Abdolazim Hasseli should take to the sucrose crystal sketch provided by

Frank T. Edelmann .

Thanks again for that detailed information above

and best regards

G. Martens

Thank you Gerhard Martens

You have clearly summarized my comments:

1) In aqueous solutions, sucrose is associated to 5 water molecules by Hydrogen bonds. The hydration number decreases with the increase of Temperature or concentration.

2) In the sucrose crystal, there is no water molecules. The sucrose molecules in the anhydrous crystal may be represented as proposed by Frank T. Edelmann

3) The reference Bressan, C. & Mathlouthi, M. (1994), Zuckerind, 119, 652 -658

was also published in the Proceedings of the 1st AVH Association Symposium. Attached is the text of this reference.

Best Regards

M. Mathlouthi