基于统计分析的发酵溶解氧与二氧化碳关系的研究

由理论分析及经验得到溶解氧与尾气二氧化碳模型,通过布拉酵母菌发酵得到实测溶解氧及尾气二氧化碳检测数据,依据经验模型计算出近似溶解氧值。应用统计分析软件SPSS得到实测溶解氧与二氧化碳及计算溶解氧的Pearson相关系数分别为-0.632和0.862,说明溶解氧与尾气二氧化碳之间存在负相关关系,而经验模型计算的溶解氧值与实际溶解氧之间具有较强的相关性。进一步采用曲线拟合对计算溶解氧值进行修正,使其更接近实际溶解氧。     

Antimicrobial effects of pressurised carbon dioxide on Brochothrix thermosphacta in broth and foods

Antimicrobial effects of high‐pressure CO₂ on Brochothrix thermosphacta were investigated in a batch system. Inactivation rates increased with increasing pressure, temperature and exposure time. B thermosphacta suspended in physiological saline was completely inactivated under 6.05, 3.02 and 1.51 MPaCO₂ treatment at 35 °C after 10, 25 and 50 min respectively. Two phases were observed in the survival curves. The earlier stage was characterised by a slow rate of decrease in the number of B thermosphacta, which increased sharply at the later stage. B thermosphacta suspended in brain heart infusion broth was completely inactivated under 6.05 MPaCO₂ treatment after 80, 50 and 30 min at 25, 35 and 45 °C respectively. About 6.90 and 5.93 log cycles of B thermosphacta were reduced under 6.05 MPaCO₂ pressure at 45 °C in whole and skimmed milk respectively. The sterilisation effects of 6.05 MPaCO₂ pressure at 45 °C on both B thermosphacta and aerobic plate count were observed after 150 and 120 min respectively in skinned meat. © 2000 Society of Chemical Industry     

Effects of high-pressure carbon dioxide on Escherichia coli in nutrient broth and milk

Bactericidal effects of high-pressure carbon dioxide against Escherichia coli were studied under 100, 75, 50 and 25 bar at 20 degrees C, 30 degrees C and 40 degrees C. E. coli suspended in nutrient broth (NB, pH = 6.75) was inactivated under 100, 75, 50, and 25 bar CO2 treatments for 50, 65, 100, and 140 min at 30 degrees C, respectively. Acidification of nutrient broth by dissolved CO2 alone might account for the bactericidal effect under pressure. E. coli was inactivated in NB with initial pH 5.50 and 4.5 at 100 bar for 80 and 95 min, respectively. Treatment at 100 bar CO2 pressure for 6 h caused a decrease of 6.42 and 7.24 log cycles in whole and skim milk, respectively.     

胱氨酸母液中L-精氨酸提取工艺研究

主要讨论了D001大孔阳离子交换树脂从胱氨酸母液中提取L-精氨酸的工艺流程及工艺条件。通过单因子实验,分别考察温度、pH、无机盐浓度(氯化钠和氯化铵)对L-精氨酸吸附率的影响;同时测定了25℃下吸附等温线、吸附动力学曲线。结果表明,吸附过程可在室温下进行;吸附的适宜pH为7-8;无机盐的存在导致吸附率迅速下降;25℃时,最大饱和吸附量约为136g/kg;平衡时间为40min。工艺最终提取率达到80％以上。     

发酵液中红霉素的含量测定

建立了红霉素的含量测定方法-初筛用紫外分光光度法(UV),复筛用高效液相色谱法(HPLC).UV法确定磷酸浓度10mol/L,反应温度80℃,反应时间3min,测定波长485nm;确定HPLC法柱温50℃,检测波长210nm.此种方法针对性好,适用于大批量的红霉素发酵液的检测.     

Effects of carbon dioxide on fermentation and aerobic stability of maize silage

The effects of carbon dioxide level (100% versus 20% v in nitrogen) during ensiling on microbial populations and subsequent aerobic stability were studied in whole-crop maize silage. In five trials, fresh maize was chopped and ensiled in 10-litre silos with the two different gas atmospheres. Changes in populations of lactic acid bacteria, acetic acid bacteria, enterobacteria, Bacillus spores and moulds were only slightly affected by carbon dioxide level. In four of the five trials, fermentation products and pH were unaffected by treatment. Yeast counts were altered by carbon dioxide level but not consistently. The yeast population in maize silage made from one source was inhibited by high levels of carbon dioxide whereas the opposite occurred in the silages from two other sources. Aerobic stability was inversely related to yeast population. In two other experiments, maize silage taken from a bunker silo was re-ensiled in 700-litre and 10-litre silos, respectively, and the same two gas treatments were used. Carbon dioxide level had little effect on microbial numbers except yeast counts, which tended to be higher in the 20% v carbon dioxide environment. Little effect on aerobic stability due to treatment was noted in either experiment. High carbon dioxide levels do not appear to improve aerobic stability consistently.     

毛细管电泳检测发酵液中1,3-二羟基丙酮方法的建立

建立了利用毛细管电泳(CE)技术快速、准确检测发酵液中1,3-二羟基丙酮含量的新方法。所用熔融石英毛细管规格为50μm×60 cm(有效长度为45 cm),分离电压为24 kV,缓冲液为pH9.5的30 mmol/L硼砂缓冲溶液,200 nm处检测DHA。结果表明,DHA标准样品的迁移时间为8.3 min,在100μg/mL～1 000μg/mL范围内线性关系良好(R2=0.999 5),加样回收率为97.79%,RSD为1.81%。测得以甘油作为底物发酵产DHA发酵液中DHA含量为3.220g/L,此方法可有效应用于产DHA发酵过程中产物的检测。     

分光光度法快速测定发酵液中杆菌肽效价

建立使用分光光度法测定发酵液中杆菌肽的方法,发酵液经预处理后使用杆菌肽敏感菌(藤黄微球菌)浊度测定杆菌肽效价.藤黄微球菌液体培养3h后,加入待测样品,再培养3h后600nm下测定吸光度,通过杆菌肽浓度与液体培养基浊度之间的线性关系测定杆菌肽效价.此方法检测准确、操作简单,可快速测定发酵液中杆菌肽效价.     

发酵液中纳他霉素的快速测定

采用紫外分光光度计法快速测定发酵液中的纳他霉素产量,以5%冰乙酸的甲醇溶液为提取剂提取发酵液中的纳他霉素,紫外检测波长为303nm。实验表明,回收率为99.6%以上。该方法简单,快速,准确。     

RP-HPLC法测定发酵液中β-苯乙醇的研究

运用反相高效液相色谱对发酵液中的β-苯乙醇进行定性定量分析确定了RP-HPLC测定发酵液中β-苯乙醇的含量的方法。色谱柱:DikmaDiamonsilC18150mm×4.6mm5μmWaters,流动相∶甲醇∶水=40∶60(v/v)流速:1.0mL/min,紫外检测波长:260nm,柱温30℃,外标法定量。结果RP-HPLC法测定浓度在4～20μL/10mL时线性关系良好,r=0.9998,平均加样回收率为97.71%,RSD为1.04%(n=5)。此方法准确,灵敏,简单,重现性好,适合于发酵液这种复杂体系中β-苯乙醇的定量分析。     

用分光光度法测定发酵液中液体脂肪的含量

用可见光光谱法快速测定工业发酵液中液体脂肪的含量。用无水乙醇作溶剂,异辛烷作萃取剂,醋酸铜作显色剂,以可见光光谱在680～700nm波长处测OD值,根据回归方程可计算脂肪油含量。结果表明,液体脂肪浓度在0.2～2.0mg/mL之间呈良好线性关系(r=0.9992),平均回收率为107.09%,RSD为1.34%(n=5)。实验证明,采用此方法比其他方法简便、准确、重现性好。     

黑曲霉xj菌株发酵液的抗菌活性研究

目的:研究黑曲霉xj菌株发酵液的抗菌谱及抗菌活性的稳定性;方法:以常见的病原细菌作为测试菌株,滤纸片法测定xj菌株发酵液的抑菌谱,通过温度、光照以及pH值的变化测定发酵液中抗菌成分的稳定性;结果:xj菌株发酵液对5种病原细菌均有不同程度的抑菌活性,其中时金黄色葡萄球菌和根癌农杆菌的抑菌效果最好,抑菌圈直径分别达到42.14 mm和38.76mm,发酵液中的抗菌成分对光照稳定,但对温度及pH值不稳定;结论:xj菌株发酵液的抗菌范围较广,提取发酵液的抑菌成分时应尽量在低于80℃以下,pH中性环境中进行.     

谷氨酸母液的脱盐研究

介绍除菌后的等电母液,改变pH下脱盐,确定了脱盐最佳工艺流程。蒸发的冷凝水可以回用,脱除的硫酸铵经干燥处理后可制得无机肥料,实现味精清洁生产。     

普鲁兰多糖发酵液中色素及蛋白的脱除

为解决普鲁兰多糖发酵液色素和蛋白脱除过程中多糖易降解、有机试剂用量大、重复次数多等问题,本论文采用D4020树脂、硅藻土、凹凸棒土等三种吸附剂,同时脱除发酵液中的色素和蛋白。通过考察时间、温度、p H、用量等因素对色素脱除率、蛋白脱除率和多糖保留率的影响,比较三种吸附剂的吸附条件和吸附效果,得出三种吸附剂对色素和蛋白均有较好的去除效果,其中硅藻土的去除效果最好。在单因素实验的基础上对硅藻土进行了正交实验,得到硅藻土的最优吸附条件为:时间60min,温度35℃,发酵液p H3.2,吸附剂用量1.6%,在该条件下脱色率为80.17%,脱蛋白率为76.28%,多糖保留率为89.82%。     

发酵液中L-精氨酸定量检测方法的研究

确立了用甲萘酚-双乙酰法定量检测发酵液中L-精氨酸 的最佳条件:40g/LNaOH溶液、80g/L甲萘酚正丙醇溶 液、0.5mL／L双乙酰正丙醇溶液各1mL作为显色液,再加 入1μL适当稀释的发酵液,30℃水浴加热15min后测其 OD540值。对显色反应的稳定性及检测方法的重现性也进 行了研究。     

臭氧用于发酵液灭菌的工业应用与节能计算

为了节约发酵液灭菌过程中蒸汽的用量,用臭氧灭菌水代替多糖发酵液中部分水的灭菌,并研究对发酵过程和结果的影响。结果表明,在水中臭氧质量浓度达到3、4、5 mg/L时,自来水达到能够满足发酵使用的无菌状态的时间分别为120、60、40 min。用臭氧灭菌好的自来水代替发酵液中50%的水,分别进行摇瓶和中试发酵,与全部采用蒸汽灭菌的发酵液发酵相比,不论是发酵过程中还原糖和多糖的变化趋势还是发酵结束时多糖的产量,采用臭氧灭菌的发酵液都没有受到影响。对10 m~3发酵罐灭菌的蒸汽耗量和冷却水进行计算,采用臭氧灭菌发酵液可以节约蒸汽47.3%,减少冷却水用量5 835 kg/罐。该研究表明,臭氧灭菌水技术可以为发酵液灭菌节约大量蒸汽和冷却水,为发酵行业的节能发展提供新方法。     

氯化钠盐析分离发酵液中的乳链菌肽工艺研究

盐析是从发酵液中分离乳链菌肽过程中的重要单元操作.本文研究了影响氯化钠盐析分离发酵液中的乳链菌肽的因素,根据乳链菌肽的生物活性单位效价,确定的最佳工艺为:加氯化钠盐量为60%的饱和度,pH3.5,温度40℃,盐析时间1.5h,乳链菌肽的收率达到94.75%.     

发酵法制备L-鸟氨酸苯乙酸盐的结晶工艺

L-鸟氨酸发酵液经膜分离、离子交换处理,再加入苯乙酸进行反应,制备结晶型L-鸟氨酸苯乙酸盐(OP)。采用单因素试验考察了晶种加入时机、晶种投加量、乙醇滴加速率及搅拌速率等因素对所得平均粒径及纯度的影响。确定起始质量浓度为800 g/L结晶液的较优结晶工艺条件为:乙醇与起始结晶液体积比为0.4时投加4wt%晶种,乙醇滴加速率0.8 m L/min,搅拌速率200 r/min。所得OP晶体平均粒径为614.7μm,纯度为98.3%,总收率为72%;将其X-射线粉末衍射图谱与文献图谱比对,确定所制备的晶体为OP晶体。