Effect of pH and storage temperature on 5-(Hydroxymethyl) furfural (5HMF) formation in USP syrup preparation

background: 5-(Hydroxymethyl) furfural (5HMF) is a compound that is formed by during thermal processing or heat sterilization of glucose, fructose and sucrose solution formulations, dialysis fluids and medical syrups. Examinations show that the storage quality dramatically reduces owing to the formation of toxic compound 5-HMF. 5HMF is considered as an irritating substance and is irritating to eyes, upper respiratory tract, skin and mucous membranes. The aim of this study is to evaluate the effect of pH and storage temperature on 5-HMF production in USP syrup. Methods: The USP syrups prepared with mixing method without heating at pH 3,4,5,6 and 8 and stored in oven at 50, 60, 70oC. The sampling has been done in several days and the amounts of 5HMF have been immediately determined by simple difference spectrophotometric method. Results: The results elucidated that low pH for preparing USP syrups leads to invert sucrose to sugars and increasing the rate of fructose dehydration, therefore an increase in 5HMF formation observed. Eventually, the high pH of syrup preparation delays the formation of 5HMF in different storage temperatures. Although, temperature influences on 5HMF formation, but the role of pH is more remarkable. Conclusion: The obtained results of this research indicated that optimal temperature and pH selection in preparation and storage of syrup cause increasing stability and reducing 5HMF formation.