V. V. Ananskikh, L. D. Shleina
All-Russian Research Institute of Starch Products – the branch of the V. M. Gorbatov Federal Science Center of Food Systems of the RAS, ul. Nekrasova, 11, pos. Kraskovo, Lyuberetskii r-n, Moskovskaya obl., 140051, Russian Federation
Abstract. In processing plants, corn starch is fluidified using endoamylases. The optimal acidity of the medium for them is in the range of 5.2–6.5 pH units. For a starch suspension fed for the hydrolysis directly from the raw starch section, it is 4.0–4.3 pH units. For a starch suspension prepared from dry starch by dilution with water, it is 6.0–6.4 pH units. Therefore, to make the enzymatic agent the most efficient, the suspension is acidified or alkalinized. For this, as a rule, 18% solution of soda or hydrochloric acid, respectively, is used. The studies aimed to determine the optimal dosage of acidifying or alkalizing reagent necessary to bring the pH of the suspension to the required level. Hydrochloric acid 5.0 N was used as an acidifier, since at such a concentration it is not volatile. Therefore, additional protective equipment was not required. We revealed a power-law dependence of pH change in the starch suspension on the dosage of the introduced reagents, such as hydrochloric acid or soda solution. The introduction of a hydrochloric acid 5.0 N solution in a volume from 0 mL to 1 mL into 500 g of the suspension prepared by diluting the starch with water allowed reducing the medium acidity from 7.0 pH units to 2.0 pH units. The increase in acidity of 500 g of starch suspension from 4.5 pH units to 6.5 pH units was achieved by introducing from 0 mL to 0.3 mL of the 18% soda solution. The established dependences were approximated by the equations allowing quickly calculating the required amount of reagent to bring the acidity of starch suspension to 5.4 pH units. The mass fraction of starch dry matter in the suspension can vary from 24% to 40%.
Keywords: starch suspension; enzymatic agents; pH; solids concentration; acidification; alkalinization.
Author Details: V. V. Ananskikh, Cand. Sc. (Tech.), head of laboratory (e-mail: Этот адрес электронной почты защищён от спам-ботов. У вас должен быть включен JavaScript для просмотра.); L. D. Shleina, senior research fellow.
For citation: Ananskikh V. V., Shleina L. D. Optimization of the Acidity of Starch Suspension during its Bioconversion. Dostizheniya nauki i tekhniki APK. 2019. Vol. 33. No. 10. Pp. 87–89 (in Russ.). DOI: 10.24411/0235-2451-2019-11019.