HPLC can provide you quantitatively. Simply, you can check TSS by refractrometer.

Thank you Jasim Ahmed for your comment. In fact, I come across on this issue about distinguish the natural sugar and added sugar in the food product when I checked through the revision of NIP in US (2015). 

As per the attached comment from NYA, refer to page 6, second point (highlighted). I am not sure is it true that the current practice of laboratory test  is limited to distinguish the types of sugar, in particular added sugar. Therefore, I open this topic for discussion to verify the simple way to distinguish the natural containing sugar in a product from added sugar.

Could there be any answer for this issue? I thought about refractrometer too but I think this is limited to beverage product such as carbonated drinks. Will it still be possible for solid/ semi-solid food (cookies/ yoghurt)? In addition, as per my understanding, it does not differentiate the types of sugar in the food product but it should provide total sugar. If I am wrong, please do advise me.

In term of HPLC, I am newbie to this analytical method for assessing sugar content in food/ beverage product. Truly appreciate if you could advise me.

Generally, HPLC will provide monosacchrides or disacchrides such as fructose, glucose and/or sucrose, lactose and maltose. Yet, how could I distinguish natural sugar and added sugar in the product? I have a few conditions for you as the examples:

Condition 1: If a product such as yoghurt, can I assume/ interpret the HPLC result as lactose (natural sugar) and sucrose/ fructose/ glucose (added sugar)? 

Condition 2: If a product is fruit juice (undefined % of fruit used), how can I distinguish natural sugar (fructose from whole fruit) and added sugar (any form such as glucose, high fructose corn syrup (HFCS), sucrose, fructose etc) in the food content?

Condition 3: If it is a solid food such as butter cookies, can I still use HPLC to determine the added sugar? If so, any specific method or literature you could suggest to me for further reading? Appreciate it very much!

Condition 4: It might be challenging for dried fruit cookies (namely raisin cookies). Can the HPLC result separate the sugar obtained from fruit (fructose, natural sugar) and added sugar (HFCS/ sucrose)?

Once again, thank you for your attention in this question. I am looking forward to hearing from your valuable opinions on this.  

Refractometer

Mr William,

I'm facing the same problem as yours regarding the matter..It is difficult to differentiate between natural and added sugar. My research group has developed cookies with no added sugar by using stevia but the sugar content value still appear.

I'm not sure if there are analysis available that can separate between natural and added sugar. If there is, please share the valuable knowledge....

Dear Researchers

The refractive index (also called Brix) given by the Refractometer is a measure of all solids present in solution including natural and added sugars and some non sugar substances. That is why a value still appear in cookies with no added sugar as Dr. Aishah found.

HPLC can be helpful if the added sugars are synthetic sweeteners.

But if the table sugar (sucrose) is added to a product containing the same, it will be difficult to detect since both will have same peaks. In this case, a control made of same product processed in same conditions without adding sugar is needed in view to compare different peak areas. Unfortunately this is possible only in laboratory scale because in large scale control of industrial products such control are not available.

Regards!

NOBOSSE

We actually can not differentiate if the added sugar is same which is present in the raw material for example Lactose (a naturally occurring monosaccharide ) in milk.