Free and conjugated polyamines and phenols in raw and alkaline-clarified sugarcane juices

Sugarcane juice contains a lot of sucrose associated with several monosacch arides, defined as low molecular mass carbohydrates (LMMC), as well as some polysaccharides and glycoproteins, which are defined as mid and high molec ular mass carbohydrates (MMMC and HMMC, respectively). These three categori es of carbohydrates can be separated by size-exclusion chromatography throu gh Sephadex G-10 and Sephadex G-50 columns, but elution profiles change dra stically after juice clarification performed by adjusting the pH value of t he juice to 8.0. In addition, polyamines and some phenolics are currently a ssociated with carbohydrate preparations, and the distribution pattern of t hese conjugates also changes after clarification. Polyamine levels generall y decrease after juice clarification. Cadaverine is completely removed from the different carbohydrate preparations, whereas spermidine is the main po lyamine occurring in association with sugarcane carbohydrates, as free or a cid-soluble form in LMMC preparation or as acid-soluble and -insoluble form s in both MMMC and HMMC preparations. Polyamines, presumably spermidine, co njugate to p-hydroxybenzoic acid in LMMC, mostly to caffeic acid in MMMC, a nd to syringic acid in HMMC preparations. HMMC-associated polyamines appear in both acid-soluble and -insoluble fractions. Syringic acid also occurs i n the LMMC preparation, but juice clarification changes it from acid-solubl e to free form, and it coelutes with sucrose.