Effect of potassium ferrocyanide on the chemical composition of molasses mash used in the citric acid fermentation

Abstract

SummaryThe addition of potassiiim ferrocyanide to the molasses substrate (mash) used in the citric acid fermentation had little or no effect on the total carbon, nitrogen, or phosphorus content of the substrate but reduced the ash content by 1-4% depending on the type and crop year of molasses. Eighteen of the 21 metals identified in beet molasses by spectrographic analysis were precipitated in part by the f,reatment. The metals known to interfere with citric acid production, particularly manganese and iron, were those most efficiently precipitated. At mash temperatures of 80°C. and approximately 100°C., precipitation was completed within 15 min. after ferrocyanide addition and the reductions in the soluble mineral content in each case were similar. At 25OC. the precipitation reactions occurred but required more than 50 hr. to complete. Significantly more total mineral and more iron, calcium, and copper were precipitated at pHs 4 and 6 than at pH 8; manganese precipitation, however, was not affected by these pH changes.

Scale-up of citric acid fermentation by redox potential control

“…The fermentation substrate was diluted sugar beet beet molasses with a total of 12.5% reducing sugars. It was treated by addition of potassium hexacyanoferrate K 4 Fe(CN) 6 , which balanced the ratio of heavy metals ions by the formation of metal complexes (Clark et al, 1965). The optimal addition of K 4 Fe(CN) 6 and H 3 PO 4 and the optimal pH was determined for every molasses batch in shake flask experiments.…”

Effect of manganese and other heavy metals on submerged citric acid fermentation of molasses

“…However, in crude molasses substrates properly treated with potassium ferrocyanide,2 a rapid rate of production and a high yield of citric acid are obtained by this organism even though the content of soluble manganese after treatment is greater than 50 ~p b .~ Clearly, more information is required on the effect of physiologically important trace metals such as manganese on the fermentation of commercially used substrates like molasses. The * NRC Postdoctorate Fellow, 1962Fellow, -1963 t NRC Postdoctorate Fellow, 1963-1965 present study was undertaken mainly to determine the effects of inangaiiese on the morphological appearance and citric acid production of A. niger NRC A-1-233 during submerged fermentation of beet, molasses. The study also included comparative tests with eight other physiologically important metals.…”

Liquid Fermentation Systems and Product Recovery of Aspergillus

“…It is important that the levels of heavy metals often found in the complex substrates employed be kept below certain critical levels, since otherwise the yield of citrate is affected and the loss of productivity results in an uneconomical fermentation. Ion exchange can be used to reduce the heavy-metal loading in molasses, but since this technique can be expensive, addition of potassium or sodium ferrocyanide will effectively remove the heavy-metal ions by chelation (Clarke et at., 1965;Hustede and Rudy, 1976a).…”