Enzymatic Conversion of Sweetpotato Starch Residue into New Food Materials

从甘薯（SP）和木薯（CA）等热带根茎作物中生产淀粉会产生大量的淀粉残留物作为副产品。这种残留物富含细胞壁物质（CWM），使其成为膳食纤维的潜在来源。本研究以马铃薯（PO）、马铃薯（CA）和马铃薯（SP）3种根茎类作物的淀粉渣为原料，对淀粉渣中的CWM进行了糖组成分析，并尝试将其酶法转化为可溶性膳食纤维。对于相对不溶的样品，需要在用1 M H_2SO_4水解之前用12 M H_2SO_4预处理以使完全水解。对于单糖分析，使用CarboPac PA 10色谱柱代替PA 1色谱柱的HPAEC-PAD方法可获得这些样品的可靠糖组成。使用这种分析方法，测定了CWM及其多糖级分的糖组成。在多糖类中， ...更多信息 作用，它是只有在半纤维素馏分中的糖组成的显着差异，特别是在半乳糖含量之间观察到的三种根作物。为了将玉米秸秆转化为可溶性膳食纤维，从土壤中分离到一株产玉米秸秆降解酶的芽孢杆菌（Bacillus sp.M4），并将其培养滤液中的粗酶液用于玉米秸秆的增溶。芽孢杆菌M4能分泌多聚半乳糖醛酸裂解酶和聚糖解聚酶，尤其是阿拉伯聚糖酶，但几乎不分泌纤维素酶。糖分析的溶解产物从CWM的三种根茎作物显示，它主要由半乳糖醛酸，和中性糖中常见的果胶馏分，表明M4酶的原果胶酶活性的存在。在水解还原产物后，通过使用HPAEC-PAD的末端糖分析来确定粗酶的作用模式。结果表明，M4酶攻击半乳聚糖以及原果胶的鼠李糖半乳糖醛酸聚糖部分，导致果胶级分的可溶性膳食纤维的释放。少

The manufacture of starch from tropical rootcrops like sweetpotato (SP) and cassava (CA) produce considerable amounts of starch residue as by-product. This residue is rich in cell wall material (CWM) which makes it a potential source of dietary fiber. This study characterized the CWMs obtained from the starch residue of three rootcrops, SP, CA, and potato (PO) in terms of their sugar composition and attempted to convert them into soluble dietary fiber enzymatically.To characterize the CWMs from the rootcrops, their sugar compositions were analyzed first. For relatively insoluble samples, pretreatment with 12 M H_2SO_4 prior to hydrolysis with 1 M H_2SO_4 was required for complete hydrolysis. For monosaccharide analysis, HPAEC-PAD method with a CarboPac PA10 column, instead of a PA1 column resulted in reliable sugar composition of these samples. Using this method of analysis, the sugar composition of the CWMs and their polysaccharide fractions was determined. Among the polysaccharide fr … More actions, it was only in the hemicellulose fraction where significant differences in the sugar composition, especially in the galactose content were observed among the three rootcrops. This has been the first report on the sugar composition of CA CWM.To convert the CWMs into soluble dietary fiber, a bacteria producing a CWM-degrading enzyme was isolated from soil, Bacillus sp. M4, and the crude enzyme solution from its culture filtrate was used to solubilize the residues. Bacillus sp. M4 has been found to secrete polygalacturonic acid lyase and glycan depolymerase activities especially arabinanase, but cellulase activity was nearly absent. Sugar analysis of the solubilized product from the CWM of the three rootcrops revealed that it is mainly composed of galacturonic acid, and the neutral sugars found commonly in the pectin fraction, suggesting the presence of a protopectinase activity in M4 enzyme. The mode of action of the crude enzyme was determined by terminal sugar analysis using HPAEC-PAD after hydrolysis of the reduced products. Results revealed that M4 enzyme attacked the galactan as well as rhamnogalacturonan moieties of the protopectin, resulting in the release of a soluble dietary fiber of pectin fraction. Less