蒸汽爆破膨化改性对玉米秸秆结构及复合板机械性能的影响

将玉米秸秆通过单螺杆式蒸汽爆破的方式进行膨化,得到不同类型膨化玉米秸秆,再与聚丙烯树脂(PP)复合制备复合板材。通过扫描电子显微镜(SEM)、反射红外(ATR-FTIR)、热重分析(TGA)、差式扫描量热(DSC)及鲍尔纤维筛分等测试,分析了秸秆膨化前后的纤维变化情况等。分析结果表明：SEM显示通过蒸汽爆破膨化机处理过的玉米秸秆能够有效进行“三素分离”,使得玉米秸秆表面结构由规整变成纤维状和粉末碎片,并且TGA、DSC和ATR-FTIR测试结果显示：在膨化过程中纤维素结构无变化,而半纤维素和木质素发生了部分的热分解。对膨化玉米秸秆与PP复合制备的复合板材的力学性能测试发现：与未膨化玉米秸秆(CS)制备的板材相比,膨化玉米秸秆(SECS)制备的板材的冲击韧性强度和拉伸强度分别增加15.69%和17.24%,而与SECS制备的复合板材的性能相比,分别经苯乙烯-丙烯酸共聚物和乙烯-醋酸乙烯共聚物修饰的膨化玉米秸秆制备的复合板材的冲击韧性强度分别增加了156.74%和100.98%,拉伸强度分别提高了83.42%和12.03%。     

Optimising pulsed microwave‐vacuum puffing for Shiitake mushroom (Lentinula edodes) caps and comparison of characteristics obtained using three puffing methods

Shiitake mushroom (Lentinula edodes) caps were puffed using pulsed microwave‐vacuum puffing (PMVP), microwave‐vacuum puffing (MVP) and microwave puffing (MP). The response surface method was used to optimise the process parameters for using PMVP to puff mushroom caps. The experiments were conducted using a central composite design to determine the visual appearance and initial moisture content (30–50%) of the mushroom caps. The initial moisture content and microwave power intensity showed highly significant linear relations with the expansion ratio and sensory evaluation. The optimal conditions for puffing mushroom caps were initial moisture content, microwave intensity, vacuum pressure and pulse ratio of 35%, 40 W g^?1, 77.5 ± 1.5 kPa and 1.35, which resulted in an optimal expansion ratio and sensory score of 163.2% and 6.83, respectively. The caps puffed using PMVP showed better textures, sensory scores and microstructures than those puffed using either MP or MVP.     

Effect of sucrose concentration of osmotic dehydration pretreatment on drying characteristics and texture of peach chips dried by infrared drying coupled with explosion puffing drying

Effects of osmotic dehydration (OD) pretreatment on the texture characteristics of peach chips after combination drying were investigated. Peach slices were immersed into 100, 300, and 500?g/L sucrose solution for 4?h, respectively, at room temperature and then predried to a critical moisture content of 0.5?kg water/kg dry matter that was determined by the effective moisture diffusivity (D_eff) curves under infrared drying at 80°C. The peach chips were then dried using explosion puffing drying (EPD). The sucrose solution with lower concentration (100?g/L) would improve the drying rate (DR) of peach slices during infrared drying. However, sucrose solution with higher concentration (500?g/L) might affect water diffusion, resulting in lower drying rate. The changes of texture characteristics of dehydrated peach were ascribed to sucrose uptake during the impregnation step. The content and constitutes of soluble sugars in peach tissue, which was significantly affected by OD treatment, were also detected in the research. The results indicated that the combined infrared and EPD drying, in which OD with appropriate concentration (300?g/L) was applied as pretreatment, could improve the drying characteristics and texture of peach chips.     

基于响应面-主成分分析法优化豆渣膨化食品的配方

目的为了克服新鲜豆渣难以膨化的缺点,添加小麦面粉、玉米淀粉和水进行复配,开发出一款膨化效果较好、品质较高的豆渣膨化食品。方法将湿豆渣、小麦面粉、玉米淀粉和水按一定比例混合均匀,利用单螺杆挤压膨化机对其膨化,然后添加防腐酒,最后进行真空包装。单因素实验以500 g湿豆渣为基准量,选取小麦面粉的质量分数、玉米淀粉的质量分数和水的质量分数作为影响因素,并以膨化度、弹性、硬度、胶黏性和咀嚼度作为评价指标,再通过响应面-主成分分析法确定最佳配方。最后测定产品菌落总数和感官分数以确定防腐酒的质量分数和产品保质期。结果在小麦面粉质量分数为83%,玉米淀粉质量分数为20%,水质量分数为31%时,产品的膨化度为5.61,弹性为0.97,硬度为1178.43 g,胶黏性为935.33,咀嚼性为1028.05。添加质量分数为1%的防腐酒后并真空包装,产品在常温下的保质期至少可达6个月。结论湿豆渣与小麦面粉、玉米淀粉和水按最优配方复配后,产品膨化效果较好,品质优良。     

基于积分分离SNPID的果蔬膨化温度控制系统设计

在果蔬膨化温度闭环控制系统中,一般PID调节器参数难以根据环境变化实时自整定,无法实现对被控制对象的精确有效控制;此外,传统数字PID控制器在系统启动、停止或因加工不同果蔬原料而大幅增减温度设定值时,会因为PID控制器积分积累的影响,引起膨化温度控制系统超调增大,从而导致果蔬膨化温度控制系统相对稳定性降低;针对上述问题,提出了以SCL语言开发基于积分分离算法的单神经元PID控制器;将该积分分离SNPID控制器应用于果蔬膨化温度控制系统中,既能避免控制系统产生较大超调,又可通过调整权系数以增强控制系统的自适应能力,从而实现对果蔬膨化温度的精确有效控制。     

Mechanism of puffing and the role of puffing inhibitors in the graphitization of electrodes from needle cokes

A mechanism of puffing that occurs during graphitization of needle coke in the electrode is proposed based on the experimental results in the literature. Gases may evolve from within needle coke grains via porosity, causing pore walls to expand irreversibly when they are softened during graphitization. Hence, extents of puffing are influenced by rate and temperature range of gas evolution, the nature of evolved gases, location of the evolved heteroatoms such as sulfur and nitrogen in the coke, and the structure (especially grain size), porosity (pores and cracks), and preferred orientation of the coke, because these factors are related to the pressure induced by the evolved gas, timing for the softening of the coke and gas evolution and the resistivity of the wall against the pressure. Porosity within a coke grain can be modified by the coke derived from binder and impregnation pitches that can diffuse into the porosity of filler coke in the electrode. The graphitization also leads to shrinkage of the carbon. Hence, the size of the electrode is influenced by both puffing and shrinkage, these having opposing effects. The extent of puffing can be described semi-quantitatively in terms of influential factors described above. Thus, it is understandable that the puffing increased the porosity in a certain range (0.1–1 μm) and that puffing is suppressed by the increased porosity of 1–100μm. Based on the mechanism, procedures for puffing inhibition are suggested including:

1. 1. moderate acceleration of graphitization

2. 2. capture of heteroatoms to be liberated

3. 3. controled gasification to increase porosity of the filler cokes

4. 4. removal of heteroatoms from the needle coke or its starting feedstock The roles of puffing inhibitors are discussed based on the mechanism of puffing.

碳酸氢钠对淀粉物料微波膨化的影响研究

研究了碳酸氢钠对淀粉物料的微波加热效果、膨化效果及产品状态的影响.结果表明添加碳酸氢钠不影响淀粉物料的介电特性及微波加热效果,含碳酸氢钠样品的温度变化情况与对照样的一致;与对照样相比,添加量为0.1%时增加了物料的膨化动力,使产品膨化率略有提高,但对膨化速率及其膨化过程没有明显的影响,而添加量为0.5%时,其膨化过程和速率都比对照样差;碳酸氢钠含量在0～0.2%之间时,产品膨化率有一最佳值,而在0.2%以后,随其含量的增加,膨化率逐渐减小;碳酸氢钠的添加量在0～0.2%之间时,膨化产品内部结构疏松,在添加量为0.5%及更高时,产品则呈现类似于对照样的孔隙状态;产品的硬度随着碳酸氢钠含量的增加而增大,脆度逐渐减小;产品黄色渐深,碱味渐浓.     

鸡肉挤压膨化休闲食品的开发研究

本文对以鲜鸡肉和淀粉为原料开发新型挤压膨化休闲食品的进料参数进行了详细的考察。试验采用可旋转中心组合设计进行实验设计,依据所得的实验数据建立了糊化率Y1及膨化度Y2与物料湿度(X1)、粒度(X2)和组成(X3)的相关数学统计模型,即Y1=95.8125+0.4825X1-0.15625X2+0.39625X3+0.52375X12-0.3475X1X2-0.235X1X3-0.7675X22+0.275X2X3-2.2838X32、Y2=0.898277-0.076283X1-0.220356X3+0.106479X12-0.19874X1X3。同时对试验数据采用响应面分析,确定了挤压膨化的最优进料参数,即进料物料湿度18%～22%、物料粒度12～16目、进料中鸡肉所占比例最高可达50%。     

发芽糙米膨化食品的研制

以糙米为原料,对发芽糙米制作膨化食品的生产工艺和配方进行系统的研究,确定出生产工艺流程和工艺参数:糙米用30℃蒸馏水密闭浸泡6 h后粉碎过60目筛,加入辅料后在20～24℃搅拌,采用配比为1∶2～1∶3混合菌种(酵母菌∶乳酸菌)发酵,产品口感最佳。