添加不同单体微波辐射合成超吸水剂的研究

以淀粉为原料,以非离了亲水基团(魔芋胶、壳聚糖、黄原胶)为单体,接枝丙烯酸,通过微波辐射法合成高质量、高性能淀粉基超吸水剂.单因素实验分别研究了引发剂、交联剂、pH值、单体浓度、微波功率、辐射时间和温度对超强吸水剂吸水倍率的影响.筛选出最适单体为黄原胶,其吸水倍率超过800倍.     

响应面优化微波法制备芭蕉芋淀粉接枝丙烯酸高吸水性树脂工艺

研究响应曲面优化微波法制备芭蕉芋淀粉接枝丙烯酸高吸水性树脂的工艺。在单因素试验的基础上,采用响应曲面法研究单体用量、引发剂用量和单体中和度对树脂吸水倍率的影响,并对共聚物结构进行分析。结果表明,微波法制备芭蕉芋淀粉接枝丙烯酸高吸水性树脂的最佳工艺为单体丙烯酸与干淀粉比8.2:1(mL/g)、引发剂用量为干淀粉质量的2.8%、单体丙烯酸中和度80.1%时,此时树脂的吸水倍率为769g/g。红外扫描吸收谱表明,接枝共聚物中存在着羧基、酰胺基等特征性亲水性基团。     

喷水工艺对木质素胶黏剂刨花板性能影响的研究

就板坯制备工艺对采用木质素胶黏剂制备刨花板进行试验研究,通过设计正交试验,获取和分析所制备刨花板的物理力学性能,探讨制板工艺过程对木质素胶黏剂刨花板性能的影响.试验结果表明,制板过程中,采用喷水工艺对木质素胶黏剂刨花板的静曲强度和弹性模量影响最大,对24 h吸水厚度膨胀率影响次之,对内结合强度影响较小;随着喷水量的增大...     

木质素改性树脂制备刨花板的工艺探究

采用工业木质素酚醛树脂作为胶黏剂,通过设计正交试验,研究制备工艺对刨花板物理力学性能的影响.结果 表明:热压时间对刨花板静曲强度和内结合强度影响最大;固化剂添加量对弹性模量的影响最大;木质素改性胶黏剂耐水性较差,其施加量对24h吸水厚度膨胀率的影响最大.本试验范围内,最佳制备工艺为:热压温度160℃、热压时间600s、...     

木薯淀粉接枝AA/AM高吸水树脂合成工艺的影响因素及优化

以过硫酸铵、亚硫酸氢钠作为引发剂,N,N'-亚甲基双丙烯酰胺作为交联剂,将木薯淀粉与丙烯酰胺、丙烯酸在水溶液中接枝共聚,合成了高吸水性树脂.单因素实验结果表明,反应温度、引发剂用量、交联剂用量、丙烯酸中和度、丙烯酰胺用量对产品的吸水倍率影响较大.正交实验结果表明:适宜的接枝共聚条件为反应温度50℃,引发剂用量0.6%,交联剂用量0.04%,丙烯酸中和度85%,丙烯酰胺用量20%.     

反相微乳液法制备芭蕉芋淀粉接枝丙烯酸盐共聚物

在氮气保护的环境下,以过硫酸铵为引发剂、N,N＇-亚甲基双丙烯酰胺为交联剂,采用反相微乳液法制备芭蕉芋淀粉接枝丙烯酸盐共聚物;确定含芭蕉芋淀粉的稳定反相微乳液体系的制备工艺：油水比为1.2:1、复合乳化剂用量为30%、乳化剂的亲水亲油平衡值(hydrophile lipophylic balance,HLB)为7.36;利用正交试验法优化利用反相微乳液法制备淀粉接枝丙烯酸盐共聚物的工艺条件,在最佳工艺(单体丙烯酸的用量16mL、引发剂用量3.5%、交联剂用量0.8%、单体丙烯酸中和度70%)条件下,制备出芭蕉芋淀粉接枝丙烯酸盐共聚物的吸水倍率可达1340g/g。红外光谱分析结果表明,聚合过程中芭蕉芋淀粉与丙烯酸发生了接枝共聚反应。     

反相悬浮法红薯淀粉/丙烯酸接枝反应工艺研究

采用反相悬浮法以淀粉接枝丙烯酸合成吸水性树脂;探讨单体与淀粉质量配比、交联剂、引发剂、油水体积比、单体中和度等因素对树脂吸水率影响,通过单因素和正交实验得到最优工艺条件:单体与淀粉质量配比5∶1、交联剂用量0.122 g、引发剂用量1.3 g、油水体积比1.3∶1、单体中和度70%;聚合物在自来水中最大吸液倍率为95 g/g,且产品具有良好吸水速率。     

荞麦淀粉接枝型高吸水性树脂的性能分析

对荞麦淀粉接枝型高吸水性树脂的吸水倍率、吸水速率、重复吸水倍率、吸盐液倍率、自然条件下的失水率以及不同温度下的失水率等吸水和保水性能进行了分析.结果表明:荞麦淀粉-丙烯酸-丙烯酰胺三元接枝共聚物吸水快,且具有较高的吸水倍率,较好的保水性和耐盐性.     

PET/PA6橘瓣型双组分纺粘水刺非织造布的碱法开纤工艺

采用碱法开纤工艺对PET/PA6橘瓣型双组分纺粘水刺非织造布进行进一步开纤,通过温度、时间、NaOH质量分数的三因素三水平正交试验,研究其碱法开纤工艺,并研究了开纤率与减量率对试样断裂强力、悬垂系数和吸水倍率等物理性能的影响。结果表明:最佳开纤工艺是温度80℃、NaOH质量分数3%、时间15 min;开纤温度是影响PET/PA6橘瓣型双组分纺粘水刺非织造布开纤率和减量率的最主要因素;在一定的开纤率范围内,试样的断裂强力、悬垂系数和吸水倍率与开纤率无明显关系,但与减量率有关。     

超吸水人棉沙障的制备和性能北大核心

以丙烯酸(AA)和丙烯酰胺(AM)为单体,过硫酸钾为引发剂,合成高聚物溶液;以胶黏剂GH-710、氢氧化铝作为交联剂,将其整理到织物上。考察了单体配比、丙烯酸中和度、聚合温度、交联剂用量等对织物吸水倍率的影响,并对吸水机理进行探讨。结果表明:水浴温度65℃,丙烯酸20 mL、中和度80%,丙烯酸和丙烯酰胺质量比为0.4∶1,过硫酸钾质量为0.12 g,胶黏剂GH-710、氢氧化铝分别为单体总质量的3%、0.5%,烘干温度80℃时,经超吸水树脂整理后的人棉沙障吸水倍率最好,可达180 g/g。     

The effect of moisture content on short infrared absorptivity of bread dough

The main objective of the study was to assess the influence of moisture content on short infrared absorptivity of bread dough. Weight loss, surface temperature and short to medium infrared absorptivity of dough were measured in a series of radiant heating experiments. A strong positive correlation between surface temperature and total heat flux absorbed by the dough samples was observed. The variation of infrared absorptivity of the dough is explained with the state of the water in the samples - vapor or liquid.     

SOLAR ABSORPTIVITY OF PEELED CASSAVA ROOT, YAM TUBER AND UNRIPE PLANTAIN FRUIT

Absorptivity is a property which governs the quantity of solar radiation absorbed by materials undergoing sun drying. A laboratory spectrophotometer was used to measure the spectral absorptivity of peeled cassava root, yam tuber, and unripe plantain fruit for wavelengths in the range 0.4–2.4 μm; 88% of solar radiation reaching the earth lies in this part of the electromagnetic spectrum. The total (i.e., integral) absorptivity calculated from the measured spectral absorptivity was 0.32 for fresh cassava which had a wet basis moisture content (M.C.) of 65%, 0.26 for fresh plantain (M.C. =61%) and 0.53 for fresh yam (M.C.=68%). Corresponding values for dried crops were 0.23 for cassava (M.C.=5%), 0.58 for plantain (M.C.=20%) and 0.77 for yam (M.C.=9%). Application of absorptivity data in evaluating heat transfer during sun drying of crops was discussed.     

Use of linear, Weibull, and log-logistic functions to model pressure inactivation of seven foodborne pathogens in milk

Survival curves of six foodborne pathogens suspended in ultra high-temperature (UHT) whole milk and exposed to high hydrostatic pressure at 21.5 degrees C were obtained. Vibrio parahaemolyticus was treated at 300 MPa and other pathogens, Listeria monocytogenes, Escherichia coli O157:H7, Salmonella enterica serovar Enteritidis, Salmonella enterica serovar Typhimurium, and Staphylococcus aureus were treated at 600 MPa. All the survival curves showed a rapid initial drop in bacterial counts followed by tailing caused by a diminishing inactivation rate. A linear model and two nonlinear models were fitted to these data and the performances of these models were compared using mean square error (MSE) values. The log-logistic and Weibull models consistently produced better fits to the inactivation data than the linear model. The mean MSE value of the linear model was 6.1, while the mean MSE values were 0.7 for the Weibull model and 0.3 for the log-logistic model. There was no correlation between pressure resistance and the taxonomic group the bacteria belong to. The order, most to least pressure-sensitive, of the single strains tested was: V. parahaemolyticus (gram negative)相似文献   

Synergistic effect of different pulses on the protein quality of rice

The protein quality of common Indian pulses, namely soybean (Glycine max), red gram (Cajanus cajan), green gram (Phaseolus aureus) and black gram (Phaseolus mungo Roxb) has been evaluated with respect to their limiting amino acids (methionine and tryptophan) and the protein fractions. Feeding experiments conducted on wistar albino rats showed a significant improvement in the biological value (BV) on rice-pulse mixed diets as compared to rice alone. However, significant reduction in the true digestibility (TD) of rice-pulse diets was observed when rice was mixed with black gram and red gram.     

甘蔗糖蜜发酵培养富铁酵母及其细胞富集铁的有机化分析

以甘蔗糖蜜为发酵原料培养富铁酵母,研究了酵母细胞对培养液中铁盐的吸收率及铁的有机化程度,实验结果显示:酵母细胞对培养液中铁盐的吸收利用率较低,为17.4%,而对于已富集到细胞中的铁离子,其有机化程度却很高,达94.3%,表明酵母是能够将无机状态的铁富集为有机态铁的有效载体。     

超声波和相转移催化剂在棕榈油皂化反应中的应用研究

以棕榈油为原料,对其非均相皂化反应进行了研究.对催化剂及皂化处理方式进行考察,并在此基础上选择反应温度、超声波功率、反应时间、催化剂添加量、KOH添加量进行了单因素优化实验.结果表明:相转移催化剂CTAB催化效果最好,超声波辅助搅拌处理方式最佳;单因素优化的最优皂化条件为反应温度70℃,超声波功率320 W,反应时间80 min,催化剂CTAB添加量0.5g(以每克油计),KOH添加量1.75 g(以每克油计).在最优条件下皂化率达到89.32％,是常规搅拌(无催化剂,无超声波作用)下皂化率的4.7倍,大大提高了效率.     

Varietal and geographic classification of french red wines in terms of major acids

Sweet potatoes (Ipomea batatas L (Lam) cv LO 323) were treated with naphthaleneacetic acid, and during storage at 25°C per cent sprouting and per cent weight loss were measured. Naphthaleneacetic acid was applied either under reduced pressure as a 1 g litre^?1 solution containing wetting agent or as a dust of 1, 10 or 100 mg per gram of talc. Application of naphthaleneacetic acid by either method reduced sprouting by more than 50% during a storage period of at least 40 days, with the exception of the 1 mg naphthaleneacetic acid per gram of talc which reduced sprouting by 29%. Treatments that significantly reduced sprouting increased water loss. A mechanism for the control of sprouting is proposed.     

Radiation processing of minimally processed sprouts (dew gram and chick pea): effect on sensory,nutritional and microbiological quality

Sprouts have become an important part of the diet because of their nutritive value and low‐calorie content. The effect of radiation processing (1 and 2 kGy dose) on minimally processed dew gram and chick pea sprouts with respect to different quality parameters was studied over a storage period of 16 days at 8 °C. Radiation treatment and storage period did not have any significant effect on the sensory as well as nutritional qualities of irradiated dew gram and chick pea sprout. No significant change (P > 0.05) was observed in the colour and firmness of irradiated sprouts as compared to control samples. However, radiation processing resulted in significant reduction in aerobic plate counts (APC), coliform counts (CC), yeast and mould count (YMC) and staphylococci counts (SC). Radiation processing of dew gram and chick pea sprouts at 1 and 2 kGy extends the shelf life without affecting sensory and nutritional qualities.     

Physicochemical,cooking and textural characteristics of some Indian black gram (Phaseolus mungo L) varieties

Physicochemical, cooking and textural properties of black gram varieties were studied and related to each other using Pearson correlation. Different varieties showed significant variation in their physicochemical, cooking and textural properties. Varieties having higher seed weight and seed volume had higher values of cooking time, swelling capacity, hydration capacity and hardness. The relationships between textural parameters of cooked grains from different black gram varieties showed a significant positive correlation of hardness with cohesiveness (r = 0.472), gumminess (r = 0.938) and chewiness (r = 0.859). Swelling index, cohesiveness and gumminess of black gram varieties were observed to be related to their fibre content. Swelling capacity and swelling index correlated well with cooking time, hardness and gumminess. Cooking time had a positive correlation with hardness (p < 0.05) and gumminess (p < 0.05) and a negative correlation with springiness. Copyright © 2004 Society of Chemical Industry     

Nutritional implications and flour functionality of popped/expanded horse gram

Utilization of horse gram and its flour in legume composite flours and products is limited due to the presence of antinutritional components, poor functional and expansion properties. Enzymatic treatment was used to improve the expansion and functional properties of horse gram to facilitate its use as an ingredient in food processing. Xylanase-mediated depolymerization of cell wall polysaccharides of horse gram lead to the development of a new expanded/popped horse gram. Expansion process of enzyme treated horse gram resulted in increased length (5.3–6.8 mm) and higher yield of expanded grains (63–98%). The expanded horse gram had lower bulk density, higher protein digestibility and more resistant starch compared to the control raw grains. Dietary fibre content of raw and processed horse gram was in the range of 14.57–16.14%. High temperature short time (HTST) conditions used during expansion process lowered the levels of phytic acid, tannins and protease inhibitors by 46%, 61% and 92%, respectively. The flour obtained from xylanase treated and expanded horse gram had higher water (204.3 g/100 g) and oil absorption capacities (98.4 g/100 g) than unprocessed flour, which had 135.8 g/100 g and 74.6 g/100 g, respectively at ambient conditions. There was a decrease in foaming capacity and foam stability in expanded gram flour. However, emulsion stability increased significantly in the processed samples. Thus, the study indicated that nutritional value and flour functionality of horse gram could be improved by processing it into a new expanded product that can be used as an ingredient in food processing.