负压蒸发工艺性能的研究

通过对现有成熟混合油负压蒸发工艺在浸出生产过程的理论分析，得出该工艺具有节能和提高浸出毛油质量的特性。并通过实际测试、分析，验证了负压蒸发的毛油和常规蒸发毛油质量上的差异，及能量消耗上的不同，展示了负压蒸发在实际运用中的优越性和良好的经济性。     

谈混合油的负压蒸发及应注意的几个问题

叙述了负压蒸发的原理及工艺,阐明了负压蒸发应注意的问题,分析了负压蒸发的工艺效果.并指出负压蒸发是节约能源、降低生产成本,增强企业竞争力的有效措施,是油脂工业未来的发展方向.     

低位冷凝混合油负压蒸发工艺的设计和探讨

本文根据在连通器中静压头和位压头之间存在相互转换关系原理,设计了低位冷凝混合油负压蒸发工艺流程。该工艺提出了现有浸出油厂(车间)在不升高冷凝设备及第一长管蒸发器高度和不增加定量溶剂泵的情况下,进行混合油负压蒸发的生产方法。     

负压蒸发二次蒸汽利用工艺节能效果的理论分析

本文简介了负压蒸发、二次蒸汽利用工艺流程,分析了主要工艺特点,并以300t/d大豆坯直接浸出为例,设定了主要工艺参数,分别计算了负压蒸发与常压蒸发工艺的蒸汽消耗,得出,负压蒸发二次蒸汽利用工艺可节约蒸汽1196kg/h、节约冷却水120t/h,每年可节约操作成本20万元,并可得到高质量的浸出毛油。     

水环真空泵在大型油厂浸出负压蒸发工艺中的实践应用

介绍了水环真空泵的工作原理、在油脂浸出负压蒸发工艺中实践应用的工艺流程和效果。从实践中发现,将水环真空泵抽真空工艺应用在大型油厂浸出负压蒸发工艺中,是完全可行的,能在达到同样抽真空效果的前提下,较常规全蒸汽抽真空工艺操作费用降低,节能效果明显,在环保方面也有较好的收益。     

负压蒸发与二次蒸汽利用生产工艺

本文简要介绍了德国ＬＵＲＧＩ公司生产的负压蒸发与二次蒸汽利用生产工艺流程及其主要工艺参数，并通过热最衡算与效果分析得出，负压蒸发与二次蒸汽利用工艺比常压蒸发工艺节省蒸汽２５％，节省冷却用水３６万吨／年，降低生产成本２１．８万元／年，并可以生产出高质量的浸出毛油。     

浸出油厂混合油负压蒸发工艺的研究与试验

本文报告了浸出油厂混合油负压蒸发工艺的研究及生产试验的结果。证明混合油负压蒸发在提高油品质量、降低能耗方面有显著效果。     

混合油负压蒸发改造实践

应用混合油负压蒸发，存在DTDC因不同含溶量的脱脂豆粕脱溶、DTDC内部出现压力波动导致蒸发系统负压下降、循环冷却水温度高的现象。设计新建厂时可以应用先进的混合油负压蒸发技术；在对已有1000t／d的正压蒸发系统改造负压蒸发系统中，增加第一蒸发器(升膜式)换热面积，由0．3m^2／t料增加为0．55m^2／t料，第一蒸蒸汽入口改为2个，接口改变径型，内部列管由Φ19改为Φ25，管间距由40mm改为50mm以减少汽阻，调整原冷凝器配置面积，将一台冷凝器改为2台并联，同样增加管径和管间距。整个系统增加2台蒸汽喷射泵，蒸汽用量由原380～400kg／t降为290kg／t，同时减少补充冷却水量25％。     

混合油负压蒸发二次蒸汽利用工艺的合理应用与设计

针对混合油负压蒸发二次蒸汽利用工艺应用于不同原料在设计和实际生产中可能遇到的问题，通过理论计算和技术分析，提出了解决问题的方法和建议。     

混合油负压蒸发,二次蒸汽利用工艺的实践

通过笔者在油厂设计和生产实践中的体会，分析混合油负压蒸发、二次蒸汽利用工艺的影响因素，并指出操作中应注意的问题。     

CHANGES IN ORGANIC ACID LEVELS DURING MALTING

A method, based on HPLC, was developed for analysis of organic acids in germinating barley and finished malt. Levels of the major respiratory organic acids were examined daily during steeping, germination and kilning in a commercial maltings. The major acids detected were citrate, malate, succinate and lactate. L-lactate but not D-lactate was produced in the grain during steeping but was rapidly lost during subsequent germination. Both L- and D-lactate were accumulated in the grain during late germination and kilning. Final levels of lactate and malate in malt were determined primarily by their rate of accumulation during kilning. A comparison of two maltings revealed that kilning time is important for final lactate levels in the malt, with long kilning times leading to high levels of both lactate isomers. It is postulated that lactate is produced during steeping by anaerobic respiration of barley whereas during late germination and kilning it is produced by proliferation of grain microbes.     

微波—蒸汽联合加热过程中冻结馒头温度和水分变化

研究微波―蒸汽联合加热过程中,不同质量馒头在采用不同微波功率时不同部位温度及水分变化。根据内外层温度相对高低可将冻结馒头复热过程分为两个阶段,前一阶段相对较长,外层温度高、中心温度低;后一阶段相对较短,中心温度高而外层温度低。馒头质量越大或微波功率越小,中心部位升温滞后期越长;提高微波功率只是改变各层温度变化速率,并不改变变化趋势;复热使各层水分含量逐渐减少,内外层水分差进一步扩大,微波功率变化只是改变失水速率,对失水总量影响不大。     

新冠肺炎疫情防控期间重庆市食品安全专项抽检结果分析

目的分析研究疫情防控期间重庆市食品安全专项的监督抽检结果。方法通过Microsoft Excel软件对疫情防控期间重庆市食品安全专项抽检结果进行统计,按照抽样区域、抽样场所、食品类别和不合格项目进行分析。结果疫情防控期间重庆市食品专项抽检样品共计1314批次,有3批次样品被检出不合格,不合格率为0.23%,抽检样品覆盖城市和农村地区,涉及36个区县、21个食品大类和11个抽样场所。结论疫情防控期间,重庆市食品安全形势整体平稳可控,但新冠肺炎疫情防控下的食品应急保障工作是一项系统性、长期性、综合性复杂工程,需要多方联动、持续推进。     

腐乳发酵过程中γ-氨基丁酸变化规律研究

腐乳是独具特色的中国传统发酵豆制品,按照后酵添加辅料的不同可分为红方、白方和青方腐乳等类型。本文研究了腐乳前发酵和盐腌过程γ-氨基丁酸(GABA)含量变化规律,并对红方、白方和青方腐乳后酵过程中GABA含量变化进行了研究,期望挖掘腐乳生产过程中GABA形成规律,为改进腐乳生产工艺富集GABA奠定基础。结果表明,GABA含量在前发酵过程明显上升,盐腌导致其含量降低。红方和青方腐乳后酵过程GABA含量先增后降,后酵45d时达最大值;白方腐乳后酵过程中GABA含量基本呈增长趋势;显示后酵不同辅料的添加影响腐乳GABA含量。     

Enzyme activities in cocoa beans during fermentation

The activities of endoprotease, aminopeptidase, carboxypeptidase, invertase (cotyledon and pulp), polyphenol oxidase and glycosidases were studied during heap fermentation of ICS-95 cocoa beans. These enzymes are of key importance in flavour precursor formation and in pigment degradation during cocoa fermentation. Optimal extraction and assay conditions were established to characterise the enzymes reactions and to quantify and compare enzyme activities during cocoa fermentation. The enzymes exhibited large differences in pH optima and stability during fermentation. Aminopeptidase, invertase (cotyledon and pulp) and polyphenol oxidase were strongly inactivated, carboxypeptidase was partly inactivated, whereas endoprotease and glycosidases remained active throughout the fermentation. Since many enzymes are inactivated during fermentation, it is generally recognised that the actual period of enzyme action is short. Although our results confirmed total inactivation for some enzymes, we show that several key enzymes are not completely inactivated during fermentation. Therefore, some enzyme reactions can continue throughout the whole fermentation process. Only polyphenol oxidase was strongly inactivated during sun and artificial drying of the beans. The other enzymes were stable during the drying process. Enzymes like endoprotease and glycosidases are still active in properly fermented and dried beans. © 1998 SCI.     

石榴果皮酶促褐变底物的研究

研究了石榴在贮藏期间果皮褐变度(BD)与总酚和单宁的变化关系,探讨了多酚氧化酶(PPO)活性变化趋势,利用薄层层析和HPLC鉴定了引起石榴果皮酶促褐变的底物。结果表明:石榴果皮单宁含量较高,贮期单宁含量下降迅速,且单宁含量下降速率与果皮褐变度呈正相关,分析得出引起石榴果皮酶促褐变的底物主要是单宁。     

冷镦钢盘条冷镦开裂原因分析

盘条中的夹杂、折叠、划伤和晶粒度不均等是造成冷镦钢冷镦开裂的原因。在炼钢时控制钢水的洁净度,连铸时防止钢水卷渣,控制速度为2.4~2.8 m/m in,轧钢时采用闭环温度控制、RSM轧制、STELMOR控冷技术。成品尺寸精度达到±0.1 mm,冷镦开裂得到了有效控制。     

液态发酵猴头菌多糖工艺优化研究(III)——还原糖、总糖、多糖、pH、氨基氮与培养时间的动态关系

研究了液态发酵猴头菌多糖过程中还原糖、总糖、多糖、pH值、氨基氮与培养时间的动态关系。结果表明 ,还原糖随培养时间的延长呈下降趋势 ,pH值则前 2d上升然后逐渐下降 ,至 14 4h后降为 3 .8,然后维持不变 ,氨基态氮随培养时间的延长呈上升趋势 ;胞内多糖到12 0h时达最大 ,然后下降 ;胞外多糖则相反 ,培养期间持续增加。     

Cell turnover and activity in mammary tissue during lactation and the dry period in dairy cows

Milk yield of the dairy cow follows a pattern termed the lactation curve. We have investigated the cellular background for this pattern. Seven mammary biopsies were obtained from each of 10 cows: at the end of lactation (d 347, equal to d 77 before next parturition); during the dry period at d 48 (4 d after dry off); 16 d before parturition; and during lactation at d 14, 42, 88, and 172. The fraction of proliferating (staining positive for Ki-67) alveolar cells was higher during the dry period (8.6%) than during lactation (0.5%). The fraction of apoptotic (staining positive by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling) alveolar cells was higher immediately after dry off (0.37%) and in early lactation (0.76%) than during other periods (0.15%). The enzyme activities of fatty acid synthetase, acetyl CoA-carboxylase, and galactosyl transferase were approximately 12-, 11-, and 4-fold higher, respectively, during lactation than during the dry period. In conclusion, mammary cell proliferation is substantial in a period near parturition but otherwise low, and apoptosis is elevated at dry off and in early lactation. The increase in apoptosis in early lactation may be due to discarding nonfunctional or senescent cells or to removal of a surplus of newly synthesized cells. The activity of selected enzymes central for milk synthesis is probably not limiting for milk production.     

Antioxidant activity and mechanism of action of thymol and carvacrol in two lipid systems

The autoxidation of purified triacylglycerols of lard and sunflower oil (TGL and TGSO) containing 0.02, 0.05, 0.10 and 0.20% thymol and carvacrol was studied at ambient temperature. The results obtained with the inhibited lipid systems (thymol - TGL; carvacrol - TGL; thymol - TGSO and carvacrol - TGSO) showed that thymol had the highest antioxidant effectiveness and activity during TGSO oxidation. Thymol and carvacrol participated in one side reaction during inhibited TGL oxidation, and thymol took part in two side reactions during TGSO oxidation. Carvacrol molecules did not participate in side reactions during TGSO oxidation. Thymol and carvacrol contributed to chain initiation to a higher degree during TGSO oxidation than during TGL oxidation. Thymol radicals did not participate in chain propagation during TGL and TGSO oxidation. Carvacrol radicals took part in one reaction of chain propagation in both lipid systems. In general, during autoxidation of lipids at ambient temperature, thymol is a more effective and more active antioxidant than carvacrol. Both antioxidants differ in the mechanism of their inhibiting action which depends on the character of the lipid medium. Thymol is a better antioxidant in TGSO than in TGL, whereas the activity of carvacrol in the two lipid systems does not differ significantly.