Kvasny Prum. 1958; 4(7): 152-155 | DOI: 10.18832/kp1958017

Determination of residual sugar in distilleries using molasses.Peer-reviewed article

M. ROSA, K. ANTONY

Fructose is the last fermenting sugar at fermentation of molasses mashes. The other component of saccharose, glucose, could be present in mashes whose residual sugars, determined by some usual reduction method, would be higher than 0.7 %. Saccharose does not form a part of residual sugar as its inversion is faster than the fermentation of products of hydrolysis. The occurrence of rafinose in the fermentable residuum is not probable. Residual sugar determined by the methods after Bertrand, after Bertrand, Obergard Ljubin Šuljatikov, Somogyi and the capillary method does not correspond to the fact. Melibiose forms only a portion in the determined residuum. According to our experiments, melibiose with the residual sugar of ca 0.30 % represents ca a half of the reduction power of the fermented mash. Calculation of the normal residual sugar (0.3 to 0.4 % of glucose) per rafinose identifies its content in mash of ca 0.9 to 1.2 %. With quadruple dilution of molasses for fermentation, residual sugar would normally correspond to an abnormal amount of rafinose in molasses from 3.6 to 4.8%. If the value of the residual sugar determined by some methods used is taken as the number giving the state of the mash at separation, then the fluctuating amount of melibiose makes this number unreliable. This error does not occur in the method after Jackson and Mathews. The method designed by Cholett  can be used for the determination of original and residual rafinose. The presence of monosaccharides is not determined by this laborious method. If the sample taken from the fermenting tug contains fermentable sugars and it is not immediately analytically processed, fermentation continues by the activity of yeasts and enzymes. The determination of the sample after several hours of standing does not express the state of the mash at separation. The addition of lead acetate for preliming (10 ml of a saturated solution to 50 ml of sample) does not stop fermentation.

(In Czech, English summary only)

Keywords: residual sugar, molasses, distillery

Published: July 1, 1958