Molasses Exhaustibility Studies Based on Sugars Analysis by Gas-liquid Chromatography

Exhaustibility tests were carried out by concentrating molasses to 4 000 poise (determined a t 40°C), adding refined sugar, crystallising at 40°C for 48 hours and carrying out on the separated molasses a series of analyses which included sugars by gas-liquid chromatography (GLC) as well as Lane and Eynon methods. Regression analysis of the results showed that purity of the exhausted molasses was strongly dependent on the ratios of non-sucrose to water and of reducing sugars to ash. Some small but in some cases consistent differences in exhaustibility of molasses from different mills were noted, which may have been due in part to differences in organic non-sugar components. A reference purity formula for use with the accurate GLC sugars analyses is presented. Purity values given by this formula are substantially lower than those derived using the target purity formula currently in use in South Africa, for two reasons : the higher viscosity aimed for in this work and the significant over-estimation of sugars by the Lane and Eynon methods on which the current formula molasses from different mills were noted, which may have is based. The new formula is GCP = 33,9 13,4 log (F+G) / A in which GCP = GLC Sucrose/dry solids purity. F = GLC Fructose O/o molasses. G = GLC Glucose % molasses. A = Sulphated ash % molasses.