葡萄枝热水预水解脱木素选择性研究

植物纤维原料中木素含量对制浆造纸原料评价和制浆工艺过程优化具有重要意义。以葡萄修剪残枝为纤维原料,在蒸煮前进行热水预水解,分别对原料得率、水解液pH值、预水解后的水解"半料"中酸不溶(Klason)木素和酸溶木素含量进行测定,进而对葡萄枝热水预水解脱木素选择性进行了分析研究。结果表明,随着水解温度升高和水解时间的延长,固相产物得率下降,水解液pH值降低,脱木素去除率逐渐升高,脱木素选择性逐渐降低。     

相思木水预水解过程中半纤维素的溶出和解聚

在不同的水解温度和时间下对相思木进行水预水解处理,采用离子色谱分析了水解液中单糖和低聚糖含量以及水解物料中葡萄糖和木糖保留率,以研究水预水解温度和时间对相思木半纤维素水解溶出和解聚行为的影响。结果表明,水预水解温度170℃、水解60 min时,水解液中总低聚糖含量达到最大值17.29 g/L,其中低聚木糖含量为12.45 g/L;水预水解温度170℃、水解80 min时,水解液中总糖含量达到最大值25.86 g/L。水解液中总低聚糖和总糖含量达到最大值后,再提高水解温度和延长水解时间,虽然可提高原料中半纤维素溶出量,但水解液中总低聚糖和总糖含量降低。     

水热预处理对制备桉木溶解浆的影响研究

本研究利用水热预处理方法辅助制备桉木溶解浆,并研究了水热预处理最高温度、保温时间、pH值对硫酸盐法制浆得率的影响.结果表明,未漂浆得率随预处理程度的增大而逐渐下降,其中半纤维素的溶出随水解液pH值的升高而增加,在较高pH值下主要以低聚木糖的形式大量溶出,水解液pH值对未漂浆得率的影响显著.研究还发现,漂白浆白度和α-纤...     

热水预水解过程杨木及水解液中组分的变化

探究了热水预水解对杨木组分、微观结构的影响及预水解液中降解产物含量变化的规律。结果表明,在保温时间60 min、保温温度155~175℃以及在保温时间0~120 min、保温温度170℃的条件下,随保温温度的升高或时间的延长,杨木热水预水解后的得率、聚戊糖和Klason木素的相对含量整体减少,纤维素的相对含量和结晶度有所增加;杨木热水预水解后的纤维形貌发生变化,出现不规则碎片和孔洞;预水解液中的酸溶木素含量增加,甲酸、乙酸、糠醛和5-羟甲基糠醛的浓度增加,糖含量随保温温度的升高不断增加,但随保温时间的延长呈先增加后减少的趋势。     

水热预处理过程中pH值对玉米秸秆水解特性的影响

本研究采用乙酸或NaOH调节水热预处理的pH值,通过分析玉米秸秆中纤维素、半纤维素和木素降解产物的变化,研究了水热预处理的pH值对玉米秸秆水解特性的影响。结果表明,在水热预处理过程中,乙酸的添加促进了纤维素和半纤维素降解,但木素溶出率略有下降,水解液中木糖、低聚木糖、葡萄糖等糖类物质含量增加,糠醛和5-羟甲基糠醛等物质含量快速提升;当NaOH用量小于3%时,随着NaOH用量增加,纤维素和半纤维素降解减少,NaOH主要消耗于半纤维素中的乙酰基脱除;当NaOH用量为3%时,此时水热预处理终点pH值为5.84,固体物料得率达到最大值为75.15%;继续增加NaOH用量,木素的溶出率开始增加,固体物料得率下降。结果显示pH值可以成为调控水热预处理水解效果的重要手段。     

热水预水解对松木及其水解液主要化学成分的影响

研究了热水预水解对松木原料中主要碳水化合物的影响,探讨了阿拉伯糖、半乳糖、葡萄糖、木糖和甘露糖的溶出规律及热水预水解对水解液中各聚糖浓度变化的影响;并研究了170℃水解温度对松木原料的化学组成如聚戊糖、苯-醇抽出物、综纤维素、木素、灰分含量的影响。结果表明,预水解过程中,各种聚糖的溶出速度从快到慢依次是:阿拉伯糖、半乳糖、甘露糖、木糖和葡萄糖,水解过程只有部分半纤维素被降解,大量半纤维素还将依赖后续蒸煮和漂白过程予以除去;在180℃的水解温度下,水解液中各聚糖的浓度随水解时间快速下降,糠醛和羟甲基糠醛的浓度则迅速增加,不利于水解液发酵制备乙醇;随着水解时间的延长,松木聚戊糖、灰分含量逐渐减少;苯-醇抽出物含量逐渐增加;综纤维素含量先快速下降,90 min后基本保持不变;木素含量先减少后又略有增加。     

蓝湿革磷酸脱铬的研究

利用紫外-可见分光光度法与测定反应液pH值相结合的方法,通过对磷酸脱铬过程中温度、磷酸用量、反应时间以及脱铬量和胶原水解量的测定,探讨了磷酸的脱铬机理。结果表明,脱铬量与胶原水解量有关,即温度越高、磷酸用量越大、脱铬时间越长,则脱铬量越大、胶原水解越严重。脱铬液pH值的变化可反映磷酸中H＋与酸根脱铬的主次作用,即溶液pH值下降,表明以酸根脱铬为主;pH值上升,表明以H＋脱铬为主。     

蜗牛水解液的制备及其乳酸发酵饮料的研究

用碱性蛋白酶对白玉蜗牛肉进行水解,探讨了水解温度、pH值、加酶量及固液比对蜗牛肉水解液水解得率的影响,通过正交试验确定了蜗牛肉水解的较佳条件,并以水解液为原料进行乳酸菌发酵,获得较佳的饮料制备工艺.结果表明：以碱性蛋白酶为水解酶,水解工艺条件为,温度50℃,pH 10.5,料液比1：5,加酶量6 000 U/g,水解3...     

热水预水解对杨木预水解液性能的影响

在硫酸盐法制浆(KP)前对杨木木片进行热水预水解处理,探讨了不同P因子对预水解液性能的影响.实验结果表明:随P因子增大,预水解液的p H不断降低,最终导致水解木片的得率不断降低,此外,预水解液中的固形物、聚戊糖、酸溶木素、糠醛和COD C r含量也呈增加趋势;当P因子≥1355时,预水解液体系中易发生物质的吸附与沉积,经傅里叶红外光谱(F T-I R)表征证实该沉积物为木素/LC C类物质;当P因子为608~1060时,预水解液和水解木片中的聚戊糖提取率具有良好的线性关系:y=1.340x+7.235,R 2=0.977;在热重分析(TGA)过程中,预水解液主要的失重温度范围为165~450℃,且当P因子由61增至1355时,失重由41%升至61%.     

牡蛎双酶水解工艺的研究

本文研究了双酶水解牡蛎蛋白的工艺条件。分析了酶用量、pH值、温度、双酶比例、反应时间等因素对牡蛎蛋白水解的影响。通过正交试验,确定其最佳水解条件为:温度45℃,pH值7.5,酶用量5000U/g,两种酶活力比(F:D)3:1,时间2h,底物浓度3%。在此条件下,水解度达28.68%,酸溶性肽得率达79.89%。牡蛎蛋白经双酶水解后的水解液可用于生产功能性食品。     

Box-Behnken法优化双酶协同水解牡蛎蛋白工艺

为获得高质量的牡蛎酶解液,以氨基氮的含量为检测指标,利用Box-Behnken分析法进行了中性蛋白酶和风味蛋白酶协同水解牡蛎蛋白工艺的优化。结果表明:最优酶解条件为温度51.7 ℃、加酶量4.7%、pH7.4、中性蛋白酶和风味蛋白酶添加量之比1:1、酶解3 h、料水比1:6时,氨基氮含量为8.197 mg/g,与理论值接近,说明优化结果良好。利用HPLC法测得酶解液中丝氨酸、组氨酸、精氨酸等含量较高,还含有牛磺酸,并且酶解液中必需氨基酸的百分比含量基本符合WHO/FAO标准氨基酸模式为牡蛎的进一步开发利用提供了一定的理论依据。     

甜玉米酶解液喷雾干燥工艺的研究

对甜玉米酶解液的喷雾干燥加工工艺进行了研究,确定了其工艺参数。根据喷雾效果,确定了麦芽糊精为助干剂。在单因素实验的基础上设计了四因素三水平的响应面实验,以麦芽糊精添加量、进口温度、物料流量、热风流量为考察因素,以出粉率为考察指标,对实验数据拟合得到的回归方程进行了统计检验和分析。最佳喷雾干燥工艺参数组合为:麦芽糊精添加量68.5%,进口温度160℃,物料流量743mL/h,热风流量0.5m3/min。在此干燥条件下,出粉率最高为48.65%,并在相同条件下进行了验证实验,实验值在95%的置信区间内很好地符合预测值。     

Quality characteristics of Chinese sausages made from PSE pork

Chinese sausages made from normal and different levels of PSE pork (100% Normal, 50%Normal+50% PSE and 100% PSE) were vacuum-packaged and stored at 4 °C for 45 days. The composition, processing yield, pH value, thiobarbituric acid (TBA) value, water activity, lactic acid bacteria counts and sensory properties of the meat products were evaluated. PSE pork loins had lower pH value, water holding capacity, moisture, fat and myofibrillar proteins content, but higher L^* value, drip loss and protein content than normal pork. Sausages made from 100% PSE pork had lower pH value, processing yield, moisture and fat content, but higher protein content than those of the 100% Normal and the 50% Normal+50% PSE treatments. Water activity was higher in the 100% PSE treatment than in other treatments. No differences in lactic acid bacterial counts among these treatments were observed. The pH values and water activity of the meat samples decreased, while lactic acid bacterial counts increased with storage time. TBA values among these treatments were not significantly different; however, the increase% of TBA values was higher for the 100% PSE treatment. TBA values of all treatments remained relatively low during storage. Chinese sausages made with 50–100% PSE pork had lower sensory texture, flavor and overall acceptability scores than the control samples, but were of acceptable quality.     

响应面法优化笋头多糖微波-超声波辅助提取工艺

本文以福建毛竹笋笋头为原材料,在单因素实验的基础上,结合响应面分析法对微波-超声波联合辅助传统水提笋头多糖的工艺参数进行优化。结果表明,微波-超声波联合辅助传统水提笋头多糖的最优工艺参数为料液比1:30 g/mL、水浴温度95℃、水浴时间2.0 h、超声波功率600 W、微波功率300 W、微波-超声波时间3.0 min。在此条件下笋头多糖得率为10.05%,对比传统热水浸提法笋头多糖得率提高了32.06%。经检测,笋头多糖的总糖、蛋白质和糖醛酸含量分别为74.87%、4.05%和1.89%。该方法能显著提高笋头多糖得率,可为竹笋的综合利用和笋多糖产品的进一步开发提供一定参考。     

荧光假单胞菌AR4产2-酮基-D-葡萄糖酸发酵条件的研究

以淀粉水解糖为碳源,研究了不同氮源、碳氮比、金属离子、接种量以及环境因子(培养基起始pH值、通气量、温度)对抗噬菌体菌株荧光假单胞菌(Pseudomonas fluorescens)AR4产2-酮基-D-葡萄糖酸发酵的影响。结果表明,氮源、碳氮比、培养基的起始pH值、通气量及温度对该菌的产酸均有显著影响。在适宜培养条件下,该菌的摇瓶产酸及发酵转化率分别可达13.5%和90%左右。     

竹材热水预抽提对硫酸盐法制浆的影响

以绿竹为原料,采用不同热水预抽提时间以及蒸煮前将热水预抽提液与竹片分离的方法,通过对比KP法制浆黑液残碱含量以及KP浆的卡伯值、得率、黏度含量等探讨了对硫酸盐法制浆性能的影响。结果表明：热水预抽提可以提高竹片蒸煮脱木素效率,达到相同的脱木素程度（相同卡伯值20）可节省约52%的有效碱用量。在预抽提时间80 min时,浆料的最低卡伯值为7.03。另外,预抽提工艺有利于提高纸浆的黏度,同时纸浆的得率也产生了较大的下降。     

草酸辅色黑豆种皮花色苷的光热降解动力学分析

为提高黑豆种皮花色苷应用性,用草酸对黑豆种皮花色苷进行辅色处理,并研究其光热降解动力学特征。添加草酸后,花色苷的吸光度明显增大,说明有辅色作用。当黑豆种皮花色苷原始吸光度与草酸物质的量浓度之比为131时,辅色效果最佳。草酸辅色黑豆种皮花色苷的光热降解动力学符合动力学一级反应规律,线性关系良好(R0.95)。较高pH条件时,相对未辅色黑豆种皮花色苷,辅色后的花色苷半衰期显著延长,热降解活化能显著增大,辅色效果较显著(P0.05)。草酸辅色处理有利于黑豆种皮花色苷在光热处理条件下的应用及保存。     

Optimization of the Enzymatic Hydrolysis of Mussel Meat

ABSTRACT:  Mussel meat was subjected to enzymatic hydrolysis using Protamex. The relationship of temperature (46 to 64 °C), enzyme : substrate ratio (0.48% to 5.52%), and pH (6.7 to 8.3) to the degree of hydrolysis were determined. The surface response methodology showed that the optimum conditions for enzymatic hydrolysis of mussel meat were pH 6.85, temperature 51°C, and enzyme : substrate ratio of 4.5%. Under these conditions a degree of hydrolysis of 26.5% and protein recovery of 65% were obtained. The produced hydrolysate, under optimum condition, was characterized in terms of chemical composition, electrophoretic profile, and amino acid composition.
Practical Application: The practical application of mussel meat hydrolysate is its use as flavoring in products such as soups, sauces, and special beverages. In addition, the product is partially digested and has great nutritional value due to its good amino acid profile and thus can be used as a food supplement in special diets.     

慈姑粉的喷雾干燥工艺优化

以慈姑酶解液为原料,研究助干剂对慈姑出粉率的影响,在最优助干剂添加量的基础上,以出粉率、含水量及感官评分为评价指标,优化喷雾干燥过程中进风温度、进料流量和热空气流量参数,确定最佳干燥工艺条件。结果表明:在麦芽糊精添加量为40%,进风温度为180 ℃,进料流量为25%,热空气流量为36 m3/h时,慈姑出粉率最高,达48.51%±0.63%,比不添加助干剂的出粉率高出31.32%,含水量为4.86%±0.07%,慈姑粉为乳白色,粉粒细小均匀,风味浓厚,冲调性好,感官性状最佳。采用助干剂协同喷雾干燥技术制备慈姑粉能显著提高出粉率,改善慈姑粉品质。     

Quantifying the combined effects of the heating time, the temperature and the recovery medium pH on the regrowth lag time of Bacillus cereus spores after a heat treatment

The purpose of this study was to quantify the lag time of re-growth of heated spores of Bacillus cereus as a function of the conditions of the heat treatment: temperature, duration and pH of the recovery medium. For a given heating temperature, curves plotting lag times versus time of heating show more or less complex patterns. However, under a heating time corresponding to a decrease of 2 decimal logarithms of the surviving populations of spores, a linear relationship between the lag time of growth and the time of the previous heat treatment can be observed. The slope of this linear relationship followed itself a Bigelow type linear relationship, the slope of which yielded a zeta-value very close to the observed conventional z-value. It was then concluded that the slope of the regrowth lag time versus the heating time followed a linear relationship with the sterilisation value reached in the course of the previous heat treatment. A sharp effect of the pH of the medium which could be described by a simple "secondary" model was observed. As expected, the observed intercept of the linear relationship between lag time and heating time (lag without previous heating) was dependent on only the pH of the medium and not on the heating temperature.