Pore Structure Regulation of Carboxyethylated Microfibrillated Cellulose Films

Carboxyethylation is a recent chemical pretreatment for preparation of microfibrillated cellulose(MFC).The carboxyethylated MFC film prepared by coating method has compact structure and high mechanical properties.In order to expand its application,three approaches including using organic solvents,different drying methods and cationic additives,have been adopted in this paper to enrich and regulate the pore structure of MFC film.The results show that all the approaches can improve the pore structure but decrease the mechanical properties of MFC film.When organic solvents such as ethanol,isopropanol and n-butanol were used to replace the water in MFC suspension or pre-dried MFC film,the pore structure of films were increased.Additionally,the film obtained by freeze-drying or air-drying after freezing in liquid nitrogen or freezer has high porosity but poor strength.The best drying process is to rewet dry MFC film,freeze in liquid nitrogen and then freeze-dry.Moreover,the addition of cationic polyelectrolytes or alkene ketone dimer(AKD)in MFC suspension can also significantly increase the film's porosity.Through the above approaches,the porosity of carboxyethylated MFC film can be regulated between 20% and 90%.     

造纸植物纤维原料制浆前的预处理技术

对植物纤维原料的几种预处理方法做了简单的介绍。经过预处理的植物纤维原料较未处理的原料在渗透性、蒸煮漂白化学品用量、机械浆能耗、化学浆得率及白度等方面有一定的优势。     

不同纤维原料对羧乙基微纤化纤维素膜性能的影响

采用6种不同的纤维原料（漂白硫酸盐阔叶木浆、漂白硫酸盐竹浆、漂白硫酸盐针叶木浆、棉短绒浆、漂白针叶木化学机械浆和玉米芯纤维素）经羧乙基化预处理和机械研磨制备了微纤化纤维素（Microfibrillarized cellulose,MFC）,并通过涂布法制备了MFC膜。探讨了原料羧基含量、研磨程度和原料种类对MFC及其膜性能的影响。结果表明,随着预处理后漂白硫酸盐阔叶木浆羧基含量的增加,MFC的保水值由98%增加到538%,MFC膜的孔隙率由37%下降至19%。当羧基含量为0.8 mmol/g时,MFC膜的抗张强度最高,达53 MPa。另外,随着研磨程度（次数）的增加,所得MFC纤丝化程度提高,MFC膜的强度先升高后降低,最高值为75 MPa。在最优的羧乙基化预处理条件和研磨程度下,由6种不同纤维原料制备的MFC膜中,漂白硫酸盐竹浆所得MFC膜的强度最高,为84 MPa,其孔隙率为25%。     

原料预处理工艺对豆瓣酱品质的影响

作者比较了两种工艺酱醅的常规理化指标。结果显示:酱醅水分、总酸、氨态氮、还原糖质量分数上存在明显差异。基于此,作者分析了两种工艺在酿造过程中存在的差异,指出由于原料预处理工艺的不同,高压蒸煮工艺熟料水分质量分数及淀粉糊化度低于常压蒸煮工艺,对成曲酶活及酱醅发酵过程带来影响,最终形成两种工艺所得酱醅常规理化指标的差异。     

Different Kinds of Microfibrillated Cellulose as Coating Layers Providing Fiber-based Barrier Properties

In this study,we investigated the barrier properties of different kinds of microfibrillated cellulose(MFC)coating layers.The air,oxygen,and water vapor permeability,as well as the water contact angles(WCA),were measured to quantify the barrier efficacy of the applied coatings.The WCA data showed that the surfaces of MFC-coated cardboards are more hydrophilic than those of uncoated cardboards.However,different MFC coatings realize different oxygen transmission rates(OTRs)and water vapor transmission rates(WVTRs).The MFC coating derived from bleached bamboo pulp subjected to carboxyethylation pretreatment(MFCCBP)gave the best oxygen and water vapor barrier performances.The OTR of the virgin cardboard(>16500 cm³/(m²·24 h))decreased to 4638 cm³/(m²·24 h)after coating with the MFCCBP.The WVTR similarly decreased from 1016.7 g/(m²·24 h)to 603.2 g/(m²·24 h).     

纤维素乙醇生产原料的综合评定

木质纤维素是地球上最丰富而且被利用率最低的可再生资源,可用作生产洁净能源——燃料乙醇。自然界蕴含着的丰富的天然木质纤维质原料,例如:玉米秸秆、玉米芯、甘蔗渣、红麻等均可作为燃料乙醇的生产原料,具有极为广阔的前景。通过实验对比详细阐述这四种纤维素质原料生产纤维素乙醇的技术过程及原料利用价值分析。     

原料与酿酒

酿酒对原料品质是有选择、有要求的。原料品质不同，其出酒率不一，风味也不相同。淀粉含量高、蛋白质适中、脂肪含量低，并含适量单宁、灰分及粗纤维的原料是较好的酿酒原料。使用优良原料酿酒，可提高出酒率1．2％，并且酒质优、风味好（琼方）     

猪肉丸主要原料对其凝胶性质和感官品质的影响

研究主要原料玉米淀粉、大豆分离蛋白、肥肉、水,在不同添加量时,对猪肉丸凝胶性质中硬度、弹性、黏聚性、咀爵性、蒸煮损失率和感官品质的影响.通过质构分析和感官评价,结果表明:玉米淀粉的不同添加量对猪肉丸的硬度、弹性、黏聚性、咀嚼性、蒸煮损失率有显著差异,在添加量22％时感官评分最高;大豆分离蛋白的不同添加量对猪肉丸的硬度、弹性、咀嚼性、蒸煮损失率有显著差异,在添加量为2.0％时感官评分最高;肥肉的不同添加量对猪肉丸的硬度、咀嚼性、蒸煮损失率有显著差异,在添加量30％时感官评分最高;在水的不同添加量对猪肉丸硬度、黏聚性、咀嚼性、蒸煮损失率有显著差异,在添加量35％时感官评分最高.     

低血糖指数原料与谷朊粉复配对面团流变学特性的影响

将不同量的低血糖指数（glycemic index,GI）原料（魔芋精粉、微晶纤维素、高直链玉米淀粉）与谷朊粉复配添加到小麦面粉中并混合均匀,研究其对面团粉质特性及拉伸特性的影响。结果表明：魔芋精粉有助于提高混合粉的综合指标,改善混合粉的粉质特性和拉伸特性;微晶纤维素使面团的粉质指标和拉伸指标下降,降低了面团的品质,其添加量应该控制在9%以内;高直链淀粉的加入使混合粉的粉质特性变差,其添加量为6%～9%时,面团的拉伸特性较好;谷朊粉能改善面团的粉质特性和拉伸特性,但添加量不宜过多,应控制在4%～6%之间。     

超声处理对制备竹浆微纤化纤维素的影响

以漂白竹浆为原料,采用中性2,2,6,6-四甲基哌啶-氮-氧化物(TEMPO)微波氧化预处理,然后在浆浓0.6%下结合超声波处理将竹浆纤维素分离解纤为微纤化纤维素(MFC)。通过表观分散性观察、透射电子显微镜(TEM)、傅里叶变换红外吸收光谱(FI-TR)和X射线衍射仪(XRD)对不同超声时间所制备的MFC的分散特性、形态特征、化学结构、结晶度和晶型结构进行表征分析。结果表明,超声2 h可以得到分散性好、完全透明的MFC,其直径分布均一(5~15 nm),而长度在微米级;超声处理不会改变纤维素的化学结构和晶体类型,但对其结晶度有一定的影响,超声1.5 h其结晶度最高66.97%,超声2.5 h后其结晶度剧烈下降至39.16%。     

Cellulose Nanowhiskers Extracted from Tempo-Oxidized Curaua Fibers

ABSTRACT

The objective of this study was to obtain nanowhiskers from bleached and milled curaua fibers. Nanowhiskers were obtained via a TEMPO system. TEM micrographies proved the fibers were obtained. FTIR analysis showed characteristic peaks of the oxidation products for the samples submitted to the treatment, suggesting that the it was effective for cellulose. The results show that the TEMPO method increased crystallinity and decreased the degree of polymerization. As for thermal stability, the nanowhiskers were more thermally stable than the other samples. Based on our findings, the use of nanowhiskers may be suitable for a variety of applications, such as the production of nanocomposites.     

酿酒原料对白酒风味的影响

采用5株酿酒酵母在酿酒原料(高粱、大米、小米、小麦、玉米)上进行发酵培养,分析其代谢产物.结果证明,小麦是良好的制曲原料;高粱产酒香,大米产酒净,小米是芝麻香型酒酿造的重要原料;证实了“小麦制曲,高粱酿酒”的科学合理性.     

产糖化酶K-1根霉曲在不同酿酒原料上的应用

研究了K-1根霉曲对不同酿酒原料的水解糖化能力。结果表明,根霉糖化酶对玉米粉、高粱粉、小麦粉、小米粉和苦荞粉的分解率在60 min时都达到了50%左右,均显著高于其他对照酶样品,特别是对小麦粉和苦荞粉的分解能力更是极显著高于其他酶样品;此外根霉糖化酶对黄豆粉也有一定的分解能力。经薄层分析发现,根霉糖化酶将酿酒原料中的淀粉分解为葡萄糖和麦芽糖两大产物。     

不同淀粉原料对鲊海椒发酵过程中香气形成的影响

以三种不同配料经自然发酵制备的鲊海椒为研究对象,采用SDE-GC/MS对发酵不同时段鲊海椒挥发性成分进行分离鉴定,比较不同食品配料和发酵时间对鲊海椒挥发性成分的影响,并对香气物质进行主成分分析。结果发现,玉米、芋头-玉米鲊海椒发酵45d挥发性成分种类最高,分别检出90种和87种,玉米鲊海椒主要成分为酯类、烷类和酸类,芋头-玉米鲊海椒主要成分为酯类、烷类和醇类;粳米鲊海椒发酵90 d检出香气种类最高为82种,主要成分为酯类、烷类和烯类。三种淀粉配料制备鲊海椒均以酯类相对含量最高,玉米、芋头-玉米和粳米鲊海椒发酵45~90 d时酯类相对含量分别为40.69%~47.25%、64.41%~74.35%和60.29%~67.29%。。综合考虑挥发性物质相对含量和种类在发酵过程中的变化以及鲊海椒发酵后的主成分得分,芋头-玉米和玉米鲊海椒以发酵45 d左右为好,粳米鲊海椒则以发酵45~90 d为好,表明不同淀粉原料在发酵过程中可影响鲊海椒风味的形成。     

蒸汽爆破技术在食品原料预处理中的应用研究进展

蒸汽爆破技术是一种新兴的原料预处理方式,该方法不需添加化学试剂,通过高温高压改变原料结构,提高原料中有效成分得率,绿色环保且高效。本文综述了近年来有关蒸汽爆破技术在食品原料预处理中的应用研究进展,包括其对食品原料中营养组分、功能成分及理化性质的影响,以期为该技术在食品领域更广泛的应用提供参考。     

保健品原料及成品中砷的测定

本文采用银盐法对保健品原料及成品中有害砷元素进行了测定,检测结果表明部分保健品原料及其成品中砷含量超过保健食品通用标准GB16740-1997的限值。方法回收率90%～106%。     

以天然原料制取新型纤维的开发与应用

文章介绍了包括天然动植物纤维及天然动植物原料人工制成的具有纯天然成分及其属性的再生纤维性能及其应用。     

Characterization of Raw Silk Fibers Obtained by Feeding Silkworms with Protein Powder

High-strength raw silk fibers were obtained by feeding the silkworm larvae with a modified feed containing down-powder. The relationship between different content of down-powder and the mechanical properties of raw silk fibers was studied. Furthermore, the morphology, chemical structures, crystallinity, and thermal properties of raw silk fibers with and without modification were also investigated. The results suggest that the tensile strength of raw silk fibers could be increased by 27% through feeding the silkworm larvae with a modified feed containing 4 wt% down-powder while keeping the original chemical structure and thermal properties of raw silk fibers.     

酱油原料蒸煮工艺的优化

为探讨原料蒸煮工艺对酱油生产的影响,用高温短时法连续蒸煮与低盐固态发酵相结合的方法,以种曲蛋白酶活力为指标,通过单因素试验确定原料蒸料温度、蒸料时间、蒸料压力的选择范围,再通过正交试验确定蒸煮最佳工艺条件。并对种曲的蛋白酶活力以及发酵各阶段的酱醅和所得成品中的氨态氮含量进行测定和分析。结果表明,蒸煮温度在115℃、时间为4min、压力为0.15MPa时,种曲中的蛋白酶活力最高,达3545U/g,头油氨氮含量达1.078g/100mL,原料蛋白质利用率达89%。在实际生产中,应用上述优化条件,不但能提高原料利用率和产品质量,还降低了生产成本,提高了经济效益。