Abstract
Starch hydrolysates have strict quality demands of production where low content of impurities is required. The quality of the product depends on the raw material, the suitability of clarification and the evaporation process of juices. The manufacture of starch products plays an essential role in numerous applications in widely different industries, such as food ingredients, cosmetics, pharmaceutical products, and other products for wide-ranging technical applications. However, the current industrial downstream processes used after hydrolysation to purify these products significantly impact the environment and have high energy demands. For this reason, it is essential to investigate other sustainable separation techniques commercially available for the industry, such as membrane separation technologies. Membrane technology could increment the quality of the product while reducing energy consumption and waste production compared with other methods. For instance, ultrafiltration (UF) membranes have demonstrated the efficient separation and purification of various sugar juices. They are pressure-driven membranes able to fractionate the product from non-sugar compounds and impurities. Therefore, as a starting point, this research evaluated two different UF membranes available in the market to treat starch hydrolysates (70 kDa and 20 kDa). The influence of two operating parameters, such as temperature and transmembrane pressure (TMP), on the separation of colour particles, sugar permeation and permeate flux from the starch hydrolysates were evaluated through the filtration processes. The 70 kDa membrane obtained the best performance at optimal operating conditions of 60 °C and 8 bar with around 27 % colour removal, the highest permeate flux value of 105.4 L/m2.h and minimum sugar loss of 3%. Finally, the results indicate the suitability of UF technology for the partial decolourisation of starch hydrolysates; however, it is recommended to continue studying the combination of UF with another separation method to eliminate the remaining impurities in the final product. These results would be a valuable guide for downstream process design and practical operation in subsequent industrial applications.
