Effects of Enzymatic Hydrolysis of Protein on the Pasting Properties of Different Types of Wheat Flour

Abstract: As one of the most effective methods to modify proteins, enzymatic hydrolysis is used widely in the preparation of wheat products in the food industry. During the same process, starch pasting occurs frequently. The effects of wheat protein hydrolysis with papain, pepsin, and trypsin on the pasting properties of 3 different kinds of flour were investigated in 5 concentrations. Results showed that the peak viscosity, trough, final, and integral area of pasting curve of these flours decreased with increasing enzymatic hydrolysis of protein, and decreased significantly with the increasing enzyme concentrations. Medium‐gluten flour was the least sensitive to enzymatic activity and weak‐gluten the most sensitive. Downtrends appeared with increasing papain and trypsin concentrations in the form of breakdown. Enzymes had no significant different effect on the peak times of strong‐ and medium‐gluten flour, but prolonged peak time slightly in weak‐gluten flour. The pasting time and temperature of strong‐ and medium‐gluten flour were significantly increased in a concentration‐dependent manner. However, there were no significant effects on the pasting times of weak‐gluten flour. These results could supply a basis for utilization of enzymatic hydrolysis of wheat protein in food industry and for further studies into the interactions between hydrolyzed protein and starch in food or processing industries. Practical Application: Illuminating the effects of enzymatic hydrolysis of protein on the pasting properties of different types of wheat flour is very important in food industry. Flour viscosity decreases after enzymatic hydrolysis of protein/gluten. Enzymes have different effects on peak time, pasting time, and pasting temperatures for different types of flour. These results could supply a basis for utilization of enzymatic hydrolysis of wheat protein in food industry and for further studies into the interactions between hydrolyzed protein and starch in food or processing industries.     

石花菜醇提物提取工艺及抗氧化、抗菌活性研究

在单因素实验基础上,通过响应面法优化石花菜醇提物的提取工艺。将石花菜醇提物经石油醚、乙酸乙酯和正丁醇依次萃取,研究不同萃取相的抗氧化和抑菌活性。结果表明,石花菜醇提物的最佳提取工艺为:60%乙醇溶液、料液比1∶35、提取时间64 min、超声功率350 W、提取温度55 ℃。在此条件下,石花菜醇提物得率为0.0165 g/g,DPPH自由基清除率为58.29%(质量浓度2 mg/mL)。不同萃取相抗氧化和抗菌活性均具有浓度依赖性,其中乙酸乙酯相活性最强,清除DPPH自由基、ABTS+自由基和羟基自由基的IC50值分别为672.4,14.1,599.7 μg/mL。对金黄色葡萄球菌和副溶血性弧菌的最小抑菌浓度(MIC)分别为156.3,156.3 μg/mL,最小杀菌浓度(MBC)分别为625,312.5 μg/mL。     

采用响应面法优化木糖醇发酵培养基

将Plackett-Burman和响应面设计相结合,对木糖醇发酵培养基进行了优化。结果表明,初始木糖浓度、酵母膏添加量以及MgSO4.7H2O浓度是影响木糖醇转化率的主要因素。优化得到的培养基组成为(g/L)木糖100.7,酵母膏5.302,NaCl6.0,MgSO4.7H2O0.379,KH2PO43,(NH4)2HPO44;通气条件为装液量100mL/250mL。此条件下木糖醇的转化率为0.784g/g。     

高速试验滑轨工程设计研究

高速试验滑轨是一种大型地面动态模拟试验设备,主要用于研究试验件在空中高速度、高加速度运行时所遇到的诸多技术问题,其核心技术是十万分之一的直线性相对精度。本文较为详细地阐述了滑轨子系统、承载梁子系统以及高精度测量子系统的设计原理和要点。其中双向受力锚固机制、承载梁子系统中的整体式道床方案以及高精度激光跟踪仪技术均为该领域的创新技术。     

南京工程学院图书信息中心能耗现状分析

由于能耗统计和分析的缺失,设计者凭主观决策的设计并不一定能达到预期的效果。以南京工程学院逸夫图书信息中心作为研究对象,分析其2014和2015年两年的能耗数据,结合实地能耗数据的调研以及使用方的反馈,通过实践数据来检验初始设计,以期得到更为客观的图书馆低能耗设计策略。分析过程中采用时间轴上年度间的纵向比较,分析图书馆能耗与气温和运营管理的关系;通过与其他大学图书馆横向的比较,准确定位分项能耗水平,引导分析设计策略。     

微波消解石墨炉原子吸收法测定食用油中铬和镉

本实验专门针对食用油开发出以微波消解-原子吸收石墨炉法准确测定油品中重金属镉、铬的实验方法,研究了油品消解的最佳处理方法及消解条件。通过基体改进剂和灰化温度的改善确定了原子吸收最佳工作条件,方法的相对偏差低于4.04%,仪器检出限为0.01μg/kg,加标回收率在95.0%~102.8%之间。实验结果表明此方法准确、检出限低、灵敏度高、分析结果令人满意。     

60Co-γ射线-离子束复合诱变法选育高产糖化酶菌株的研究

以黑曲霉UV-4为出发菌株,利用60Co-γ射线与离子束进行复合诱变。试验表明:经复合诱变,可以获得高产糖化酶的菌株AnUVγN+7,酶活达到1 100.9U/mL,是原始菌株UV-4(156.1U/mL)的7倍,菌株经过7次传代,结果显示酶活较稳定,以此可选育高产糖化酶菌株。     

Near-Critical Natural Circulation Flows Inside an Experimental Loop: Stability Map and Heat Transfer

The near-critical CO₂-based natural circulation loop (NCL, or thermosyphon) has been proposed in many energy conversion systems, such as the solar heater, waste heat recovery, next-generation nuclear cooling, and so on. There is an increasing need to obtain detailed information about such systems, as it is less verified from a basic system operation viewpoint. This paper presents an experimental investigation of a near-critical CO₂ thermosyphon. The closed thermosyphon is specially designed for high-pressure (in the critical region, from 6.0 MPa to 15.0 MPa), natural circulation flows. The basic transient flow behaviors and parameter behaviors are found to be dependent on initial pressure. The system stability evolution from subcritical oscillating flow to supercritical stable operations is presented. From the experimental data analysis, the stability map for the current supercritical natural circulation loop system is given. It is found that the stability pressure lines will divide the operation into stable, transition, and unstable regions. It is found that the effectiveness of the cooler will greatly affect the system stability, while the heat transfer efficiency is mainly controlled by the heater conditions. Parameter evolutions of the fluid temperature, mass flow rate, and loop pressure are presented in this paper. The heat transfer dependency on operation pressure and evolution mechanisms are also discussed in detail in this paper.     

某含金高硫铜矿石浮选试验研究

采用新药剂对某含金高硫铜矿石进行了系统浮选试验研究.通过对比试验,发现采用传统的捕收剂黄药和黑药选别含金高硫铜矿石,虽然能够有效地回收含金硫化物,但获得的精矿产率高,铜和金的品位低,很难售出.而采用新药剂选别该类型矿石,可以使问题得到有效解决.新药剂对硫化铜矿物具有非常好的选择性,在粗选阶段采用新药剂可以有效回收硫化铜矿物,获得合格的铜精矿;在扫选阶段,采用黄药和黑药可以有效回收黄铁矿和其他硫化矿物,保证铜和金的回收率;扫选中矿单独处理,中矿采用六偏磷酸钠分散剂来消除矿泥对精选作业的影响,精选获得的混合精矿可以直接销售.     

太阳能光伏光热(PV/T)系统在建筑中的应用研究

"碳达峰、碳中和"目标下,可再生能源在建筑中的应用受到越来越多的重视.在诸多可再生能源中,太阳能作为最容易与建筑结合的可再生能源之一,具有清洁、安全、稳定、高效等特点,对其深入开发利用是未来建筑能源结构性改革的需求.本文对国内外太阳能光伏光热系统的技术最新发展现状进行了梳理和总结,研究了太阳能光伏光热(PV/T)系统在建筑中的应用方式,分析了太阳能光伏光热系统的典型案例与发展趋势,为实现产业升级、降低成本、扩大应用提供参考.