The major factors which affect the colour of the product are

1.exposure to light

2.temperature extremes and/or moisture.Moisture is the key to dispersion of the water soluble ingredients in the product and changes in the levels of moisture can cause colour changes.

3.pH. At certain pH levels, some contents degrade or shift to a different which causes, less-stable color.

4. Ascorbic acid-It acts on azo-linkages which causes colours to fade.

5.Heat-Prolonged eat exposure should be avoided

6.Oxygen-Some contents scavenge on the oxygen present in the product and cause degradation which causes loss of colour.

7.Metal ions-Presence of metal ions also can degrade the colour of the product.

8.Microbial growth-It causes changes in the end product stability.The level of sugar in the syrup generally retards the growth of most microbes due to high osmotic pressure,but certain microbial metabolites may cause the changes.

Color stability can also be be affected by the moisture, protein or fat content of the end product. 

I hope this can help a bit.

Regards

Hi, Have you evaluated the stability off all compounds in your syrup? Best regards

no sir, what should i do then?

i am talking about large scale production....

regards 

You need to know what compound and the cause that changes. If I may know, what's the ingredients of your herbal syrup?

Hi, I think at first, you should do stability studies of all your standards (API)  and sample of syrups in the selected solvent of extraction, mobile phase and stationary phase for a certain of time (at expected time of storage) You can compare the TLC profile of the fresh solutions and solutions that keep at certain of time; the profiles should be identical (no new peaks/spots, the identity and purity evaluations are acceptable), best regards

 The major factors which affect the colour of the product are

1.exposure to light

2.temperature extremes and/or moisture.Moisture is the key to dispersion of the water soluble ingredients in the product and changes in the levels of moisture can cause colour changes.

3.pH. At certain pH levels, some contents degrade or shift to a different which causes, less-stable color.

4. Ascorbic acid-It acts on azo-linkages which causes colours to fade.

5.Heat-Prolonged eat exposure should be avoided

6.Oxygen-Some contents scavenge on the oxygen present in the product and cause degradation which causes loss of colour.

7.Metal ions-Presence of metal ions also can degrade the colour of the product.

8.Microbial growth-It causes changes in the end product stability.The level of sugar in the syrup generally retards the growth of most microbes due to high osmotic pressure,but certain microbial metabolites may cause the changes.

Color stability can also be be affected by the moisture, protein or fat content of the end product. 

I hope this can help a bit.

Regards