热水处理对预包装鲜切马铃薯品质的影响

目的研究不同热处理时间对预包装鲜切马铃薯品质的影响。方法采用60℃热水对预包装鲜切马铃薯进行处理,时间分别为0.5,1.0,1.5 min。测定贮藏中的亮度L*值,颜色饱和度C*值,细胞膜透性,多酚氧化酶(PPO)和过氧化物酶(POD)活性,感官品质等指标,并进行比较分析。结果在温度为4℃的保存条件下,60℃热水处理1 min能较好地维持鲜切马铃薯的白度,保持细胞膜的完整性,抑制PPO和POD的活性,延缓鲜切马铃薯的褐变。结论热水处理可以改善鲜切马铃薯的品质,1 min热水处理组贮藏至第6天时仍具有良好的商品品质。     

涂膜处理对氩气气调包装的鲜切香菇品质的影响

采用海藻酸钠和壳聚糖涂膜处理并结合氩气气调,对鲜切香菇进行包装,检测了鲜切香菇在贮藏中的呼吸强度、失重率、硬度、白度、PPO 活性以及感官评定等指标,研究了不同配比复合液对鲜切香菇贮藏保鲜效果的影响。 结果表明,0. 5% 壳聚糖+1. 5% 海藻酸钠处理组,能有效地抑制鲜切香菇的呼吸速率和失重率,并维持最高的硬度值,且在贮藏后期,其白度值明显高于其他处理组,更易让消费者接受。     

薄膜包装对鲜切生菜货架期品质的影响

目的 探究不同薄膜包装对鲜切生菜货架期色泽和营养品质的影响,以期为鲜切生菜的保鲜提供便捷高效的方法。方法 本研究采用不同厚度(20、30和40 μm)的聚乙烯(PE)薄膜以及微孔PE薄膜包装鲜切生菜,于(4±1)℃条件下模拟货架8 d,以带孔PE薄膜包装作为对照组,研究这5种薄膜包装对鲜切生菜货架期间表型、感官评分、质量损失率、袋内O2和CO2、色差、叶绿素、类胡萝卜素、叶黄素、可滴定酸、抗坏血酸(VC)和丙二醛(MDA)含量的影响。结果 不同厚度的PE薄膜以及微孔PE薄膜包装能在一定程度上减少鲜切生菜色泽的变化、质量损失率的上升以及营养成分的损失。其中,20 μm薄膜和微孔膜包装可以显著抑制鲜切生菜质量损失率,a^*、b^*和MDA的升高,保持袋内较高的O2,并抑制CO2的积累,减缓叶绿素、类胡萝卜素、叶黄素、可滴定酸、抗坏血酸和感官评分的下降,进而维持较高的品质,延长货架期。与20 μm薄膜相比,微孔膜会造成鲜切生菜相对较高的质量损失率。结论 20 μm厚度的PE薄膜更适合作为鲜切生菜保鲜的包装材料,可延长货架期2~3 d。本研究为鲜切生菜保鲜包装袋的选择提供依据,推动鲜切预制菜产业的发展。     

基于地方特产品牌下的包装设计研究

地方特产是当地人怀念家乡、外地人出门旅游争相购买的热门产品,是许多人走亲访友的必备佳品,在特产包装上的创新设计能够提升品牌的整体形象,增强其市场竞争力.本文将从视觉传达、地域文化的凸显和材料选择等三个方面研究地方特产品牌的包装设计,在分析地方特产包装设计特色的基础上,传达较为实际的设计理念,为基于地方特产品牌的包装设计...     

气调包装对鲜切猕猴桃和木瓜贮藏品质的影响

采用以托盘盛装、上覆 PP 塑料薄膜的形式,对鲜切猕猴桃和木瓜组合拼盘进行了气调包装。 在 5 ℃ ,相对湿度 90% 的环境下,研究了 MAP1(3% O2 ,8% CO2 ,89% N2 )、MAP2(70% O2 ,30% N2 )、MAP3(80% O2 ,20%N2)3 组气调包装对鲜切猕猴桃和木瓜切面颜色、硬度、可溶性固形物含量、可滴定酸及 Vc 含量等指标的影响,并与空白组进行了对比。 结果表明,70% ~ 80% 的高氧条件对鲜切木瓜和猕猴獭娲盘保鲜效果最好,并且延长了它们的货架寿命。     

气调包装对超市常温销售的鲜切芹菜品质影响研究

在超市常温销售的环境下,分别选用体积分数(后同)为5% O2,15% CO2,80% N2;10% O2,10% CO2,80% N2;20% O2,60% CO2,20% N2 3种气调比例对鲜切芹菜进行气调包装.测定芹菜的失重率,黄化率,维生素C,叶绿素和感官评价等指标.实验结果表明,在这3种气调搭配中,10% O2,10% CO2,80% N2对鲜切芹菜的品质保存效果最好.     

乙醇复合抗坏血酸处理对鲜切苹果贮藏品质的影响

目的 为了研究乙醇处理对鲜切苹果贮藏品质的保鲜效果。方法 以鲜切‘寒富’苹果为材料,比较乙醇、乙醇复合抗坏血酸（Vc）溶液处理对鲜切苹果在4 ℃下贮藏品质的影响。分析鲜切苹果包装内的气体成分变化、可溶性固形物含量、硬度、颜色、质量损失率等品质指标,还对组织衰老进程、酚类物质代谢和活性氧代谢及微生物数量进行评价。结果 研究表明,体积分数为30%的乙醇溶液浸泡鲜切苹果能有效保持冷藏货架期间果实的硬度、可溶性固形物含量、较低的质量损失率,延缓果实组织表面颜色变化和褐变的发生;进一步研究显示,乙醇可能是通过抑制酚类物质的氧化分解,从而减少了醌类物质在组织中的积累;乙醇处理还有利于抑制果实组织中电导率的升高,此外经乙醇处理后,大肠菌群和菌落总数均显著小于对照组和复合处理组中的数量。结论 采用乙醇处理鲜切‘寒富’苹果,有利于保持果实的品质,并延缓衰老和褐变进程,从而延长了货架期。     

活性壳寡糖涂膜处理对鲜切苹果品质的影响

目的研究壳寡糖涂膜与植物精油复配涂膜处理对鲜切苹果品质的影响。方法将鲜切苹果样品分别经过蒸馏水、壳寡糖、壳寡糖+体积分数为0.25%的百里香油、壳寡糖+体积分数为0.06%的肉桂油、壳寡糖+体积分数为0.25%的百里香油+体积分数为0.06%的肉桂油涂膜处理2 min,然后在灭菌滤纸上晾干,置于托盘后用PVC保鲜膜密封,于4℃下贮藏。分别于0,3,6,9,12,15,18 d后取出并测定各项生理生化指标,即亮度(L~*)、彩度(C~*)、硬度、质量损失率、抗坏血酸含量、多酚氧化酶活性、过氧化物酶活性、脂肪氧合酶活性。结果壳寡糖+体积分数为0.25%的百里香油+体积分数为0.06%的肉桂油的涂膜处理可显著维持鲜切苹果的颜色、硬度和抗坏血酸含量,贮藏期内PPO和POD活性均低于其他处理组。壳寡糖涂膜可显著延缓鲜切苹果的质量损失速率,降低样品中脂氧合酶的活性,延缓样品的衰老速度。结论壳寡糖涂膜对鲜切苹果有很好的保鲜效果,复合精油的添加能更好地维持鲜切苹果在贮藏期间的品质。     

海藻糖涂膜对鲜切苹果品质的影响

目的为了抑制鲜切苹果发生酶促褐变,改善其口感,延长其保质期。方法以富士苹果为实验材料,研究质量分数不同(0%,0.1%,0.5%,1%,5%)的海藻糖涂膜剂处理对鲜切苹果的保鲜效果,并测定褐变指数、Vc含量、SSC含量、可滴定酸含量、MDA含量等指标。结果采用海藻糖涂膜剂处理鲜切苹果的最佳质量分数为1%,可显著提高其品质。经质量分数为1%的海藻糖处理鲜切苹果后,其色泽口感俱佳,褐变抑制作用较强,明显降低了褐变指数和MDA的增长率,延缓了Vc、SSC和可滴定酸等含量的下降。结论海藻糖涂膜处理不仅可以抑制鲜切苹果在贮藏期间的褐变进程,而且还可以赋予其更好的风味,提高产品的品质,延长其保质期,对鲜切果蔬的保鲜研究具有重要意义。     

不同包装材料对鲜切榴莲保鲜品质的影响

目的研究不同包装材料在低温贮藏条件下对鲜切榴莲保鲜品质的影响。方法实验材料为新鲜榴莲,榴莲剥皮后挑选96块,分别用LDPE,HDPE和LDPE/PP薄膜袋对鲜切榴莲进行普通包装,对照组不进行包装,每组试验重复4次。在(4±1)℃条件下贮藏,分别于2,4,6,8,10 d后进行取样,测定各项指标。结果 LDPE薄膜、HDPE薄膜和LDPE/PP复合膜能延长榴莲保鲜期。结论 HDPE薄膜袋在抑制榴莲失重率、维生素C减少速率、褐变等方面明显优于LDPE薄膜和LDPE/PP复合膜。     

Combined effects of hot water treatment (HWT) and modified atmosphere packaging (MAP) on quality of tomatoes

Effects of hot water treatment (HWT) and modified atmosphere packaging (MAP) on quality of tomatoes were studied. Prior to packaging with low‐density polyethylene (LDPE) film (0.02 mm in thickness), tomatoes were immersed in hot water (42.5°C) for 30 min. Control tomatoes were not treated and were stored for 2 weeks at 10°C and then for 3 days at 20°C without packaging. Steady states of O₂ and CO₂ concentrations inside the package were about 5 and 8%, respectively, and were reached after 6 and 4 days of storage, respectively. MAP reduced weight loss of tomatoes to about 41% of that of unpackaged fruit during a 2‐week storage period. The use of a combination of HWT and MAP reduced weight loss and decay, inhibited color development and maintained firmness of tomatoes but had no effect on soluble solids content or titratable acidity. HWT slightly reduced mold growth of tomatoes stored in MAP. Packaging of control fruit in MAP resulted in stimulation of mold growth around the stem end of the fruit after about 1 week of storage and also resulted in cracking and decay. HWT could be used as disinfectant for tomatoes prior to storage in MAP in order to reduce microbial growth, cracking and decay that may be caused by excessive water vapor inside the package. Copyright © 2003 John Wiley & Sons, Ltd.     

Effects of hot water pre-extraction on surface properties of bagasse soda pulp

In this work, the effects of hot water pre-extraction of depithed bagasse on the soda pulping and surface properties were studied. The conditions of hot water pre-extraction were: maximum temperature 170 °C, heat-up time 90 min, time at maximum temperature 10 min, and solid to liquor ratio (S:L) 1:8. Consequently, the pre-extracted and un-extracted bagasse chips were subjected to soda pulping at 160 °C for 1 h with 11, 14 and 17% active alkali charge and an S:L of 1:5. The results showed that the hot water pre-extraction increased bagasse surface texture porosity by hemicellulose degradation. Therefore, the delignification was faster for pulping of pre-extracted samples. At a certain charge of alkali, pre-extracted samples showed higher screened yield and lower Kappa number. For instance, at 17% alkali charge, pre-extracted bagasse gave 11.3% higher pulp yield compared with the un-extracted ones. Inverse gas chromatography (IGC) results showed that the hot water pre-extraction changed the active sites on the bagasse surface, decreasing the dispersive energy and the basicity character, and affected the particle morphology. The pulping process decreased the hydrophobicity and the basicity of the bagasse surface. The surfaces of un-extracted and pre-extracted bagasse pulps had similar properties but different morphology. The pulps present higher surface area and permeability with more reactive capacity.     

Effects of hot rolling and homogenisation treatment on low alloy steel ingot

ABSTRACT

The effects of hot rolling and homogenisation treatment on the microstructure and mechanical properties of low-alloy transformation-induced plasticity (TRIP) steel were studied. With increasing the reduction in thickness during rolling, the band spacing and the average ferrite grain size decreased with the consequent enhancement of mechanical properties. Homogenisation treatment resulted in the gradual fading of the banded morphology, more homogeneous microhardness profile, and twice total elongation compared to the as-cast counterpart. The experimentally observed homogenisation time judged by the disappearance of the banded structure was in agreement with the obtained values based on the band spacing and elemental analysis. This work provided scientific evidence for the assumptions used to derive the homogenisation formulae.     

Effects of hot isostatic pressing and heat treatment on cast cobalt alloy

Investment cast biomedical alloys are often heat treated to refine the microstructure and improve mechanical properties. Test specimens of American Society for Testing and Materials F75 alloy (Co–28 wt-%Cr–6 wt-%Mo) were cast and solidified at two cooling rates, which influenced the size and area fraction of secondary phases (carbides) precipitated at grain boundaries and in interdendritic zones. The specimens were then subjected to hot isostatic pressing and age hardening. This produced smaller globular carbides of reduced area fraction, and reduced the size of micropores, independent of as cast characteristics. Strength and hardness were not significantly altered. The most significant effect of the post-casting treatment was to increase the ductility of the alloy, most likely due to the dissolution of brittle intergranular carbides and reduction in pore size.     

Effects of homogenisation treatment on microstructure and hot ductility of aluminium alloy 6063

Abstract

Several homogenisation treatments were applied to direct chill (DC) cast ingots of aluminium alloy 6063, in order to analyse the resulting microstructures developed from these diverse conditions and their effects on the hot ductility of this alloy. Imaging was performed using scanning electron microscopy (SEM) and a focused ion beam (FIB) instrument. These techniques identified variations in distribution and morphology of second phase particles (AlFeSi and Mg₂Si). FIB results for the various AlFeSi particles correctly identify their shapes in three dimensions (3D). The particles were identified by energy dispersive spectroscopy (EDS) in the SEM, and by X-ray diffraction (XRD) for bulk samples. Hot tensile testing (HTT) was conducted between 470 and 600°C to asses the hot ductility for each condition. The inferior ductility of as cast samples was due to the poor bond strength of the β AlFeSi phase at the grain boundaries. Homogenised samples, which contain α AlFeSi, exhibited improved ductility. Samples that were water quenched following homogenisation were absent of Mg₂Si precipitates, when these elements remained in solid solution. These exhibited the highest ductility.     

太阳能热水系统的标准化概述

一、太阳能热水系统与工程标准化的特点目前,太阳能热水系统与工程技术的发展和产业化对标准化工作提出了严峻的挑战。传统标准化的主要模式是当技术发展成熟以后再进行标准化工作,这种方式显然已     

热模压预成型工艺参数对复合材料帽型长桁质量的影响

本文采用热模压预成装置将碳纤维单向预浸料层板制备成帽型结构长桁预成型体,通过对不同工艺条件下制备的帽型长桁预成型体的表观质量、厚度和纤维偏转角度进行检测,考察和分析了成型温度和速度对预成型体质量的影响规律。当成型温度较低时,由于树脂的黏度较高,预浸料层间摩擦力较大。预成型体表面出现褶皱现象,并且纤维由于受到层间剪切的作用而出现角度偏转。当成型温度较高时,树脂受到压力作用更易流动。这不仅降低了预成型体的厚度,同时也减弱了树脂束缚纤维的能力,使纤维偏转角度增加。而当成型速度增加时,预浸料层间的摩擦力使纤维的偏转角度增大。因此在预成型过程中,为了提高预成型质量,工艺温度和成型速度应控制在一定范围内。      

Effects of combined UV and chlorine disinfection on corrosion and water quality within reclaimed water distribution systems

The effects of combined ultraviolet (UV) and chlorine disinfection on corrosion and water quality were assessed in a model reclaimed water distribution system (RWDS) using annular reactors (ARs). UV irradiation not only enhanced the inactivation of heterotrophic bacteria, but also reduced the required initial chlorine dose. Moreover, UV pretreatment induced less changes of corrosion products composition and decreased iron release and turbidity of effluents resulted from Larson–Skold Index (Li) of reclaimed water changing, enhancing the stability of water quality through RWDS. The corrosion bacteria within the biofilm on the corrosion scales could grow selectively with different disinfection processes. In the AR with combined UV and chlorine treatment, the iron-oxidizing bacterium (IOB) Acidovorax defluvii and the iron-reducing bacteria (IRB) uncultured Rhodoferax sp. and uncultured Geobacter sp. appeared on the biofilm. In contrast, in the AR treated with chlorine alone, the IOB Sediminibacterium salmoneum and the IRB uncultured Geobacter sp. were predominant in the biofilm. In the latter, S. salmoneum respiration predominantly contributed to the oxidization of Fe(II), whereas in the former, either Fe(II) or acetate acted as a donor for A. defluvii respiration, causing an increased depletion of oxygen by the oxidation of Fe(II). Therefore, under the former conditions, the composition of corrosion bacteria could result in lower corrosion rate, decreasing the effect of Li changes on iron release. All results indicated that UV irradiation enhanced water quality stability in the RWDS.     

Effects of inorganic surface treatment on water permeability of cement-based materials

The permeability of the cement-based materials can be used as an important indicator of their durability. Surface treatment is a simple way to reduce permeability and improve durability of cement-based materials. This paper studied the effects of fluosilicate and sodium silicate surface treatments on the permeability of cement-based materials using the Autoclam water permeability and water absorption testing method. The experimental results showed that both fluosilicate and sodium silicate surface treatments could effectively reduce the permeability of cement-based materials. However, fluosilicate worked within the first 28days after treatment, while sodium silicate showed more obvious effect at later ages. Autoclam water permeability index exhibited an exponential relationship with the water absorption of the cement-based materials. In addition, mercury intrusion porosimetry result suggested that these inorganic surface treatment agents could reduce the porosity of surface layer of cement-based materials.