This study was designed to evaluate the indices that affect the quality of sugar beet root processing in relation to sugar loss in final molasses. This quality is affected by late sugar beet root harvesting and the infestation with root rots resulted in a significant increase of the inverted sugars, K, Na and α-amino-N concentrations with detrimental consequences for processing. For this purpose, samples of sugar beet molasses and sugar beet roots were taken during the processing (from two different designs of production lines) and research fields of Delta Sugar Company during different times in the 2021 and 2022 processing seasons early season, middle season and late season (from the middle of February to late March, from early April to middle of May and from the middle of May to late June, respectively). During the processing season, sucrose content in sugar beet roots declined significantly, while K, Na, amino N, inverted sugars and other ingredients accumulated in the beets, therefore, the quality of sugar beet roots degraded dramatically. The quality of sugar beet increased significantly from 74.8±0.024% to 83.8±0.024% during the season. Whereas the purity of sugar beet juice elevated significantly from 84.8±0.019 to 87.9±0.029% during the season. These findings revealed that there is a reversible relationship between the quality of sugar beet, the sugar losses percentage in beet molasses and the concentration of alpha-amino nitrogen, sodium and potassium in sugar beet. Therefore, the future needs of the processing industry could change the criteria of quality assessment.