Using it as fast as possible is simply the best option. Otherwise store it at 2-4 degree centigrade temperature. Being a good source of carbohydrate it is very prone to contamination by any fermentative microorganism which will ferment it to CO2 and other metabolites.
You can sterilize the herbal syrub by membrane filters or by suitable solvent or leave it in gamma irradiated atmosphere for 6 hours and then keep it in refrigerator till use,
SYRUP MUST BE FILLED IN AMBERED COLOUR BOTTLE AND PREVENT FROM DIRECT SUNLIGHT . IT SHOULD BE STORE AT 20-25 DEGREE C UNDER DARK. LASTLY USE SOME PRESERVATION TO RETAIN THE EFFECT OF ALL HERBS IN HERBAL SYRUP.
@Dr Ashish suttee: thanks sir for your opinion , actually i have already filled syrup in amber color bottle and also stored it in room temperature. also i am using Na benzoate and citric acid as preservative, is there any preservative that i can use ?
Benzoate and citric acid are preservatives. The reason for fermentation is microbial metabolism of herbal syrup constituents, principally carbohydrates. You can reduce risk of fermentation through Pasteurization (treatment at < 100oC), apply Appertization (> 100oC) or eliminate fermentation through sterilization.
Dear Dr. SS, it is always better to use the herbal preparations as early as possible i.e. as fresh as possible. If at all you need to preserve them then let us know the effective herbal ingredients in it so that suitable preservative strategies would be discussed/sugged.
@ dr CK : thanks for your opinion, here the ingredients is Glycyrrhiza glabra (Yastimadhu), Triphala, Nardostachys jatamansi (Jatamansi), Operculina Turpethum (Nishoth), fumaria officinalis (Parpataka), Cyperus rotundus (Nagarmotha)
If you are the one who is preparing the herbal formulation, try to exclude microbes as far as possible (by observing strict aseptic measures), also if possible avoid inclusion of readily fermentable sugars, then store it under condition that is unfavorable for the culprit fermentative microbes (very low temperature) and then use it as quickly as possible. But if it is prepared by some one else then store it properly and use it promptly.