Marzo Cristina, Díaz Ana Belén, Caro Ildefonso, Blandino Ana
Department of Chemical Engineering and Food Technology, Faculty of Sciences, IVAGRO, University of Cádiz, Campus Universitario de Puerto Real, 11510 Puerto Real, Spain.
Foods. 2020 Sep 24;9(10):1351. doi: 10.3390/foods9101351.
In this study, the production of a hydrolysate rich in fermentable sugars, which could be used as a generic microbial culture medium, was carried out by using exhausted sugar beet pulp pellets (ESBPPs) as raw material. For this purpose, the hydrolysis was performed through the direct addition of the fermented ESBPPs obtained by fungal solid-state fermentation (SSF) as an enzyme source. By directly using this fermented solid, the stages for enzyme extraction and purification were avoided. The effects of temperature, fermented to fresh solid ratio, supplementation of fermented ESBPP with commercial cellulase, and the use of high-solid fed-batch enzymatic hydrolysis were studied to obtain the maximum reducing sugar (RS) concentration and productivity. The highest RS concentration and productivity, 127.3 g·L and 24.3 g·L·h respectively, were obtained at 50 °C and with an initial supplementation of 2.17 U of Celluclast per gram of dried solid in fed-batch mode. This process was carried out with a liquid to solid ratio of 4.3 mL·g solid, by adding 15 g of fermented solid and 13.75 g of fresh solid at the beginning of the hydrolysis, and then the same amount of fresh solid 3 times every 2.5 h. By this procedure, ESBPP can be used to produce a generic microbial feedstock, which contains a high concentration of monosaccharides.
在本研究中，以耗尽的甜菜粕颗粒（ESBPPs）为原料，生产了一种富含可发酵糖的水解产物，该水解产物可用作通用的微生物培养基。为此，通过直接添加真菌固态发酵（SSF）获得的发酵ESBPPs作为酶源进行水解。通过直接使用这种发酵固体，避免了酶提取和纯化阶段。研究了温度、发酵固体与新鲜固体的比例、用商业纤维素酶补充发酵ESBPP以及使用高固含量补料分批酶水解的效果，以获得最大还原糖（RS）浓度和生产率。在50℃下，以补料分批模式每克干燥固体初始补充2.17 U的纤维素酶，分别获得了最高的RS浓度和生产率，分别为127.3 g·L和24.3 g·L·h。该过程在液固比为4.3 mL·g固体的条件下进行，在水解开始时加入15 g发酵固体和13.75 g新鲜固体，然后每2.5 h分3次加入相同量的新鲜固体。通过该程序，ESBPP可用于生产一种含有高浓度单糖的通用微生物原料。
