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ARS Home » Southeast Area » New Orleans, Louisiana » Southern Regional Research Center » Commodity Utilization Research » Research » Publications at this Location » Publication #393100

Research Project: Improved Conversion of Sugar Crops into Food, Biofuels, Biochemicals, and Bioproducts

Location: Commodity Utilization Research

Title: Effects of harvest temperature and rainfall on molasses purity, reducing sugars, and target purity difference

item Terrell, Evan
item Heck, Emily
item VERRET, CHARDCIE - LSU Agcenter
item WAGUESPACK, HERMAN - American Sugar Cane League

Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 3/30/2022
Publication Date: 3/30/2022
Citation: Terrell, E.C., Heck, E.L., Eggleston, G., Verret, C., Imbachi Ordonez, S., Waguespack, H. 2022. Effects of harvest temperature and rainfall on molasses purity, reducing sugars, and target purity difference. Meeting Proceedings. 11,2022:772-782.

Interpretive Summary: The target purity difference (TPD) is a metric used by sugar producers to estimate how much sugar is being left behind in molasses. This provides a way to assess efficiency of sugar production at a mill and to compare performance among different sugar mills. TPD is based on the quantity of reducing sugars (glucose and fructose) and ash in the molasses sample. This study presents analysis of molasses data with local harvest weather conditions for several previous years of sugar production (2014-2020) in Louisiana. Based on our results, the average weekly temperature during cane harvest appears to have some impact on the characteristics of resulting molasses and its TPD. Specifically, there is evidence to suggest molasses reducing sugar content increases with increasing harvest temperature, while ash content shows the opposite trend. This implies that the calculated TPD tends to increase with increasing harvest temperature.

Technical Abstract: Target purity difference (TPD) is a useful metric for estimating molasses exhaustion during sugar production. TPD is quantified by taking the difference between a target purity value and the true purity of the molasses. Target purity can be expressed as a function in terms of the reducing sugar (glucose plus fructose) to ash ratio and provides a measure of the minimum amount of sucrose in a solution as a percent of the total dissolved solids. In order to assess the broader impacts of TPD estimation in the Louisiana sugar industry, this work presents a preliminary investigation of the effects of harvest weather conditions on molasses purity and TPD. The following molasses data were collected from Louisiana sugar mills (and utilized in this analysis) over the time period of 2014-2020 sugar production seasons: true purity, reducing sugars, and conductivity ash (as percent of total solids), target purity (calculated) and TPD (calculated). Subsequently, weather data (average weekly temperature and precipitation) were collected for several Louisiana areas (Baton Rouge, Jeanerette, New Iberia, Thibodaux) corresponding to sugar mill locations. Statistical analyses of molasses and weather data suggest that the effect of average weekly precipitation tends to be not significant, while average weekly temperature may have a significant impact on TPD estimation. Specifically, qualitative observation of the trends between molasses data and temperature suggest that conductivity ash decreases and reducing sugar increases with respect to increasing temperature. Because TPD is a function of the reducing sugar to ash ratio, this has the practical effect of a decreasing trend in calculated target purity with temperature, and an increase in calculated TPD with temperature.