摘要：
Native rice starch lacks the versatility necessary to function adequately under rigorous industrial processing, so modified starches are needed to meet the functional properties required in food products. This work investigated the impact of enzymatic hydrolysis and cross-linking composite modification on the properties of rice starches. Rice starch was cross-linked with epichlorohydrin (EPI) with different concentrations (0.5%, 0.7%, 0.9% <em>w/w</em>, on a dry starch basis), affording cross-linked rice starches with the three different levels of cross-linking that were named R<sub>1</sub>, R<sub>2</sub>, and R<sub>3</sub>, respectively. The cross-linked rice starches were hydrolyzed by α-amylase and native, hydrolyzed, and hydrolyzed cross-linked rice starches were comparatively studied. It was found that hydrolyzed cross-linked rice starches showed a lower the degree of amylase hydrolysis compared with hydrolyzed rice starch. The higher the degree of cross-linking, the higher the capacity to resist enzyme hydrolysis. Hydrolyzed cross-linked rice starches further increased the adsorptive capacities of starches for liquids and decreased the trend of retrogradation, and it also strengthened the capacity to resist shear compared to native and hydrolyzed rice starches.
摘要：
Chitosan oligomers (COS) were obtained by enzymatic hydrolysis and H<sub>2</sub>O<sub>2</sub> oxidative treatment, and then separated into different fractions using ultra-filtration membranes. Each COS<sub>M</sub> fraction prepared using enzymatic hydrolysis retained its structure, especially the reduced end residue (-NH<sub>2</sub> group), and had a peak for molecular weight. On the other hand, each COS<sub>H</sub> fraction prepared by oxidative treatment had partly damaged -NH<sub>2</sub> groups and two peaks for molecular weight. These results indicate that the same COS fractions prepared by the two methods differ in their amino groups and in their molecular weights, though they can both pass through the same size ultra-filtration membrane. The effect of COS on the retrogradation of intermediate amylose rice starch (IA-RS) was also investigated. The 5 k < COS<sub>M</sub> < 10 k fraction had the best anti-retrogradation ability; the retrogradation ratio of IA-RS with this fraction was reduced by 14.5%, compared to the control, and its relative crystallinity was only 59.69%. 10 k < COS<sub>M</sub> < 30 k fraction was second best, while the COS<sub>M</sub> < 5 k fraction had no effect. Therefore, the molecular size of COS determined its anti-retrogradation capability. All COS<sub>H</sub> fractions from oxidative treatment had no effect on the retrogradation
作者机构：
[Liu, Gao-Qiang; Han, Wen-Jun; Wang, Xiao-Ling] Cent S Univ Forestry & Technol, Coll Life Sci & Technol, Hunan Prov Key Lab Forestry Biotechnol, Changsha 410004, Hunan, Peoples R China.;[Liu, Gao-Qiang; Lin, Qin-Lu] Cent S Univ Forestry & Technol, Natl Engn Lab Rice & By Prod Further Proc, Changsha 410004, Hunan, Peoples R China.
通讯机构：
[Liu, Gao-Qiang] C;Cent S Univ Forestry & Technol, Coll Life Sci & Technol, Hunan Prov Key Lab Forestry Biotechnol, Changsha 410004, Hunan, Peoples R China.
关键词：
medicinal fungi;Ganoderma lucidum;submerged culture;response surface methodology;ganoderic acid Me
摘要：
Enhanced ganoderic acid Me (GA-Me, an important anti-tumor triterpene) yield was attained with the medicinal fungus Ganoderma lucidum using response surface methodology (RSM). Interactions were studied with three variables, viz. glucose, peptone and culture time using a Central Composite Design (CCD). The CCD contains a total of 20 experiments with the first 14 experiments organized in a fractional factorial design, with the experimental trails from 15 to 20 involving the replications of the central points. A polynomial model, describing the relationships between the yield of GA-Me and the three factors in a second-order equation, was developed. The model predicted the maximum GA-Me yield of 11.9 mg·L−1 for glucose, peptone, culture time values of 44.4 g·L−1, 5.0 g·L−1, 437.1 h, respectively, and a maximum GA-Me yield of 12.4 mg·L−1 was obtained in the validation experiment, which represented a 129.6% increase in titre compared to that of the non-optimized conditions. In addition, 11.4 mg·L−1 of GA-Me was obtained in a 30-L agitated fermenter under the optimized conditions, suggesting the submerged culture conditions optimized in the present study were also suitable for GA-Me production on a large scale.
摘要：
为优化低值豆粕液态发酵生产大豆多肽工艺,应用Minimum Run Equireplicated Res IV析因设计进行了主效因子的筛选,根据主效因子影响及变化方向进行爬陡坡试验,最后,应用二次旋转中心复合响应面设计对液态发酵多肽工艺进行了优化,优化工艺条件为豆粕浓度6.0%、pH 8.0、装瓶量93.0 mL.300 mL~(-1)。最优条件下模型预测多肽含量为707.204μg.mL~(-1),验证试验结果为683.023±9.23μg.mL~(-1)(n=6)。
摘要：
Rice starch was cross-linked with epichlorohydrin (0.3%, w/w, on a dry starch basis) and oxidized with sodium hypochlorite (2.5% w/w), respectively. Two dual-modified rice starch samples (oxidized cross-linked rice starch and cross-linked oxidized rice starch) were obtained by the oxidation of cross-linked rice starch and the cross-linking of oxidized rice starch at the same level of reagents. The physicochemical properties of native rice starch, cross-linked rice starch and oxidized rice starch were also studied parallel with those of the two dual-modified rice starch samples using rapid visco analysis (RVA), differential scanning calorimetry (DSC), dynamic rheometry and scanning electron microscopy (SEM). It was found that the levels of cross-linking and oxidation used in this study did not cause any significant changes in the morphology of rice starch granules. Cross-linked oxidized starch showed lower swelling power (SP) and solubility, and higher paste clarity in comparison with native starch. Cross-linked oxidized rice starch also had the lowest tendency of retrogradation and highest ability to resistant to shear compared with native, cross-linked, oxidized and oxidized cross-linked rice starches. These results suggest that the undesirable properties in native, cross-linked and oxidized rice starch samples could be overcome through dual-modification.
