影响Camembert干酪均匀成熟因素的研究

对影响Camembert干酪内部均匀成熟的因素和生产关键控制点进行了研究,并用质构仪对自制干酪和市售商品化干酪进行了TPA对比分析.在生产过程中,影响Camembert干酪内部均匀成熟的控制点包括:凝块热缩时间、盐渍时间、成熟温度及成熟相对湿度等条件,通过单因素实验和正交实验确定了热缩时间45min,盐渍时间30min,成熟温度13℃,相对湿度95%为最佳工艺参数.     

影响Camembert干酪均匀成熟因素的研究

对影响Camembert干酪内部均匀成熟的因素和生产关键控制点进行了研究,并用质构仪对自制干酪和市售商品化干酪进行了TPA对比分析。在生产过程中,影响Camembert干酪内部均匀成熟的控制点包括:凝块热缩时间、盐渍时间、成熟温度及成熟相对湿度等条件,通过单因素实验和正交实验确定了热缩时间45min,盐渍时间30min,成熟温度13℃,相对湿度95%为最佳工艺参数。      

干酪促熟附属发酵剂的研究进展

干酪成熟时间较长且费用较高,干酪促熟成为降低生产成本的有效途径之一。干酪促熟常用的方法有酶法、修饰发酵剂细胞、提高成熟温度、高压处理等,但均存在一定的不足,限制了其在干酪工业中的应用。非发酵剂乳酸菌可促进干酪风味的形成并加速成熟．已成为干酪促熟方法的研究热点之一。介绍了干酪生产及成熟过程中微生物的作用,特别介绍了干酪附属发酵剂发展的原由并综述了其在干酪成熟过程中研究进展。     

促进干酪陕速成熟方法的研究进展

干酪的成熟对其风味和质地有极大影响,且成熟时间的长短又涉及生产成本和企业效益.本文从干酪的成熟原理出发,深入探究了提高成熟温度、添加外源酶和附属发酵剂等方法加快干酪成熟的机理,以及对干酪感官品质的影响,为干酪的快速成熟提供理论依据.     

成熟温度对Mozzarella干酪蛋白水解和质构的影响

研究了温度为4,7,10℃时对干酪成熟过程中蛋白水解和质地的影响。结果表明,随着干酪成熟温度的升高,成熟期间干酪中可溶性氮与总氮的比值增加较快,干酪的硬度下降速度也较快。说明在较高的成熟温度下,干酪在较短的时间内能够达到成熟的状态。     

牛乳超滤及工艺条件改变对切达干酪促熟及其品质的影响

采用超滤技术对牛乳进行浓缩预处理,再制作干酪。选择不同升温时间、成熟温度,研究其对切达干酪的组成和产率、蛋白质分解以及质构的影响。结果表明:延长升温时间有利于干酪产率提高。通过测定各干酪pH4.6SN及12%TCA可溶性氮质量分数发现,提高成熟温度均能加快实验组干酪的蛋白质分解。经质构仪测定由超滤浓缩乳制作的干酪弹性、凝聚性、黏性差异均不显著,而提高温度使各干酪质地的弹性、凝聚性、黏性都有所降低,且差异显著(P<0.05),与其在同等条件下的蛋白质水解度有一定关系。结合感官评定,提高成熟温度后,苦味的出现使干酪的滋味和气味的整体评分降低;同时提高成熟温度也降低质地的整体评分,其干酪硬度降低,咀嚼性较差。     

干酪促熟方法的研究进展

干酪成熟时间较长，费用较高，导致生产成本增加。因此干酪的促熟受到人们普遍关注。干酪促熟常用的方法有酶法、修饰发酵剂细胞、悬浮液系统、提高成熟温度、高压处理等。其中提高成熟温度和高压处理法不需要额外的干酪添加剂，是应用于生产中成本较低且易实现的方法。本文主要就以上两种方法促熟干酪作以详述。     

比萨干酪工艺及其功能特性分子基础

阐述了乳中的酪蛋白胶束如何经过生产和成熟逐步形成比萨干酪的微观结构,以及该结构如何影响干酪的功能性如融化性、拉伸性、出油性和起泡性.并应用上述分子理论分析省略热烫拉伸、混合酸化、添加钙等生产实例,说明生产工艺是通过作用于干酪的微观结构而影响其功能特性.本文在力图澄清国内比萨干酪生产中一些疑惑的同时,说明只有从认识干酪的分子基础入手,才可能通过控制工艺条件改善干酪的功能特性或提高生产的经济性.     

水牛奶干酪中多肽提取条件的优化

采用单因素和正交试验,以干酪多肽提取率为评价指标,对干酪多肽提取的工艺进行优化。结果表明,最佳工艺为料液质量比1︰10,提取温度30℃,提取时间30 min。对霉菌干酪、外源酶促熟干酪和自然成熟干酪三种干酪进行多肽提取,提取率能够达到95%以上。     

影响干酪品质的因素

叙述了关于干酪生产过程中原料乳、凝结剂、发酵剂、干酪成分、成熟温度等因素对干酪品质影响的作用机理。同时也对干酪成熟过程中这些因素对干酪品质的影响进行了分析。     

Behavior of Escherichia coli O157:H7 during the manufacture and aging of Gouda and stirred-curd Cheddar cheeses manufactured from raw milk

This study was conducted to examine the fate of Escherichia coli O157:H7 during the manufacture and aging of Gouda and stirred-curd Cheddar cheeses made from raw milk. Cheeses were manufactured from unpasteurized milk experimentally contaminated with one of three strains of E. coli O157:H7 at an approximate population level of 20 CFU/ml. Samples of milk, whey, curd, and cheese were collected for enumeration of bacteria throughout the manufacturing and aging process. Overall, bacterial counts in both cheese types increased almost 10-fold from initial inoculation levels in milk to approximately 145 CFU/g found in cheeses on day 1. From this point, counts dropped significantly over 60 days to mean levels of 25 and 5 CFU/g in Cheddar and Gouda, respectively. Levels of E. coli O157:H7 fell and stayed below 5 CFU/g after an average of 94 and 108 days in Gouda and Cheddar, respectively, yet remained detectable after selective enrichment for more than 270 days in both cheese types. Changes in pathogen levels observed throughout manufacture and aging did not significantly differ by cheese type. In agreement with results of previous studies, our results suggest that the 60-day aging requirement alone is insufficient to completely eliminate levels of viable E. coli O157:H7 in Gouda or stirred-curd Cheddar cheese manufactured from raw milk contaminated with low levels of this pathogen.     

罐头食品包装应练好“内功”

罐头食品的质量安全问题 一直是质检部门及消费者关注的热点, 如何在不加防腐剂的条件下延长罐头食 品的保质期,更是罐头食品生产企业在 加工中的难点。中国罐头工业协会顾问、 高级工程师杨邦英教授指出,罐头行业 在管理和封罐工艺两方面的瓶颈需要突 破:在管理方面,一是产品质量抽检的形 式,使得一部分不合格却没有被检出的 产品钻了空子,流入到市场;二是大量的 出口产品,由于国外对于产品卫生质量 的关注而忽略了产品本身的感官质量, 使得一批口感差,感官性能次的产品出 口到国外。在工艺方面,更需要各生产企 业及操作人员的重视。     

Effects of ripening conditions on the texture of Gouda cheese

Summary The effects of ripening temperature, type of packaging film and storage period before packaging were related to the degree of proteolysis and the texture of Gouda cheese, so as to determine the optimum ripening conditions. Gouda cheeses from a local plant were subjected to different ripening conditions. A factorial design of 2³× 5 was used, where the three factors selected in two levels were: (1) time of storage before packaging, 4 and 10 days, (2) ripening temperature, 10 and 20 °C and (3) plastic film, BK1 and BK5 (Grace, Quilmes, Argentina). Ripening time was a fourth factor analyzed; sampling times were 15, 25, 35, 49 and 70 days after production. Cheeses traditionally ripened (without packaging) were also analyzed. Water content and pH were determined. Nonprotein nitrogen (soluble in 12% trichloracetic acid (TCA)) was quantified by the Kjeldhal method. Cheese texture was analyzed by compression and relaxation tests which were done by using an Instron Universal Testing Machine (Instron Corp., Canton, MA, USA). The pH and water content of cheeses which ripened at 20 °C were lower than the corresponding ones ripened at 10 °C. Only ripening time and temperature had a significant effect on water content, nonprotein nitrogen concentration and rheological parameters. Results show that texture properties of Gouda cheese ripened in plastic films with low gaseous permeability are similar to those of traditionally ripened Gouda. Texture development was accelerated by increasing the storage temperature.     

Influence of milk centrifugation, brining and ripening conditions in preventing gas formation by Clostridium spp. in Gouda cheese

This study examined milk centrifugation, increased salt concentration, and low ripening temperature as potential strategies to prevent late blowing caused by gas-forming Clostridium spp. in Gouda cheese. The survival of clostridia spores in cheese brine and their ability to enter Gouda cheese during brining was also evaluated. Centrifugation (3000 x g for 30 s) of contaminated milk resulted in > 60% spore reduction, with increased spore reduction at greater centrifugal forces. Low levels of C. tyrobutyricum and C. sporogenes spores survived in saturated (23%, w/v) brine with 2% (v/v) added whey at 15 degrees C for 63 days, while C. beijerinckii and C. butyricum spores were not detectable on days 4 and 35, respectively. Spores of C. tyrobutyricum in brine infiltrated Gouda cheese during 2 h of brining at 13 degrees C resulted in production of small gas holes during ripening. In Gouda cheese slurry stored at 13 degrees C, three C. tyrobutyricum strains plus one of three C. sporogenes strains germinated in the slurry with no added salt. Of three C. tyrobutyricum strains stored at 13 degrees C in slurries with higher water-phase salt concentrations of 2.4 and 3.6%, two strains and one strain germinated, respectively. No germination of spores was detected in any cheese slurry stored at 5 or 8 degrees C. Milk centrifugation, increased percent water-phase salt, absence of spores in brine, and decreased ripening temperature are all potentially important measures against gas production by Clostridium spp. in Gouda cheese.     

论啤酒生产中二氧化碳工控原则

论述了啤酒生产过程ＣＯ２的形成机理与作用原理，着重讨论了生产过程ＣＯ２的工控技术及成品中ＣＯ２的作用关系，阐明了生产中ＣＯ２的合理工控原则。     

HACCP思想在指导农村商品米酒卫生监督中的运用

为了引导农村商品米酒的规范发展,保证农村米酒消费者的身体健康与米酒千百年来的传统工艺健康传承。通过HACCP思想的指导作用,给米酒生产与销售过程中的每个环节作了具体的危害分析,确定了米酒生产与销售过程中的卫生监督的关键控制点,并制定了相应的"三维一体"(控制生产与销售的自控、卫生监督的监控、社会群众的群控为一体)卫生监督措施和校正办法,为有效地预防和减少米酒在生产与销售过程中的危害因素的发生提供参考。     

机织过滤布的设计与生产

阐述了机织过滤布的用途及原料品种、规格的选择和织物结构的设计,并从理论和实际两方面介绍了其产品生产工艺的确定,得出整经工序汽蒸筒纱和织造工序增加打纬力,严格控制温湿度是生产的关键.并介绍了目前国内生产状况.     

芝麻糖成型机的设计

改进芝麻糖手工艺,设计出一种新型芝麻糖压片机械可以实现芝麻糖压片工艺的自动化生产,该机采用输送带传动,通过进料装置,温度控制,实现芝麻糖生产的机械化、连续化、自动化.结合生产实际,综合考虑芝麻糖的形状特点和生产率,采用多层分铺原理实现芝麻糖的成型.所设计的设备结构简单,操作、维护方便,满足了实际生产的需要.     

Fate of Listeria monocytogenes in Gouda microcheese: No growth,and substantial inactivation after extended ripening times

This challenge study demonstrates that Listeria monocytogenes does not grow in Gouda cheese: during the first 8 weeks of ripening no growth was observed and between 8 and 52 weeks viable numbers declined significantly in a well-established Gouda microcheese system. Cheese milk was artificially contaminated just prior to addition of the starter culture. Three individual L. monocytogenes strains were used, including strains originating from cheese, a cheese plant environment and a reference strain. During curd formation, viable numbers of L. monocytogenes increased by 0.5 log cfu g⁻¹, resulting from entrapment in the curd. No growth was observed during the first 8 weeks of ripening. A significant decline in the viable numbers of L. monocytogenes was observed in Gouda cheese that was ripened for longer than 8 weeks. Two factors that could possibly control the fate of L. monocytogenes in Gouda cheese were lactic acid and water activity.