预酸化对云南乳扇凝乳的影响

本研究利用热处理的酸乳清对牛乳进行预酸化处理,研究酸乳清对乳扇凝乳效果的影响,根据热烫拉伸工艺的需要,控制凝乳的pH值,分析不同的温度和pH值对凝乳效果的影响。结果表明:凝乳温度34℃、凝乳pH值5.2时,酪蛋白流失最少,凝乳效果最好。乳扇加工工艺中通过酸乳清对牛乳进行预酸化处理,可以解决凝乳过程中凝块pH值不固定的问题。     

不同工艺参数对乳扇质构的影响

本试验研究了不同工艺参数对乳扇质构的影响,根据TPA试验数据获得乳扇加工的最佳工艺条件。结果显示,将原料乳杀菌加热至65℃与酸木瓜汁混合进行凝乳,调节凝乳乳清p H值为4.8、凝乳时间60s揉捏成团,在洗涤温度70℃条件下,洗涤4min加工制得的乳扇凝团硬度、弹性、内聚性、黏附性、胶黏性等质构特性较好。     

云南传统乳扇加工与保鲜

民间乳制品乳扇，形如扇页。现采用食用酸替代酸乳清作凝固剂，添加山梨酸钾作防霉剂，真空包装低温贮存试验，摸索出了乳扇加工的最佳工艺条件和保鲜贮存方法，为乳扇的深加工和开发提供了理论依据。     

红枣山羊乳乳扇配方及加工工艺研究

本研究建立了红枣山羊乳乳扇的加工工艺,并对其配方及加工的工艺参数进行了优化。结果表明:(1)红枣山羊乳乳扇的加工工艺:加入食用白醋→加热至65℃→加入灭菌山羊乳→迅速搅拌→形成絮状凝乳→揉搓成团→洗涤→加入白砂糖、大枣粉→混合均匀→制成饼状→入模成型→自然干燥24～48 h→成品。(2)红枣山羊乳乳扇的配方为:食用白醋使用量占鲜羊乳的12%,大枣粉、白砂糖质量分别占凝乳块的10%,5%。     

Mozzarella干酪生产工艺参数的优化

Mozzarella干酪属Pasta Filata干酪,由于加工过程中经过热烫拉伸,从而形成特有的纤维状结构,使这种干酪具有多种功能特性.根据干酪含水量和水分含量和脂肪占干物质的百分数(FDM)的差异,Mozzarella干酪分属不同的品种,分别用于鲜食、Pizza配料和加工再制干酪的原料.在国内外Mozzarella干酪的研究基础上,Mozzarella干酪的产业化生产中的关键工艺参数进行优化探讨.试验结果表明,Mozzarella干酪的关键工艺优化参数为热收缩温度39℃,堆酿pH值5.25,热烫拉伸温度62℃.     

云南特色食品乳扇中铝含量的检测技术研究及其健康风险评估

建立干法灰化-电感耦合等离子发射光谱法测定乳扇中铝的含量。采用干法灰化对牛奶和乳扇样品进行前处理,利用电感耦合等离子发射光谱法测定乳扇中铝含量,采用靶标危害系数法（Target Hazard Quotients,THQ）评价乳扇中铝含量对人体存在的潜在健康风险。铝在0.0~10.0 mg/L质量浓度范围内线性关系良好,干法灰化前处理方式的检测结果满足方法学要求,回收率为91.90%~96.80%,精密度为3.59%~6.52%;检出限为0.15 mg/kg。重金属暴露接触对人体的健康风险评价结果表明,乳扇存在膳食摄入潜在风险。干法灰化-电感耦合等离子发射光谱法操作简便、准确性好,适合乳扇批量产品检测,对于保证乳扇安全性具有重要的意义,为乳扇的质量安全性评估提供了一定的理论依据。     

桑叶用热风平穿流设备干燥加工的工艺条件优化

桑叶的干燥加工工艺对干燥产品的品质影响较大。应用热风平穿流设备对桑叶进行低温干燥加工,以桑叶的干燥速率和复水性作为考核指标,通过四因素三水平正交试验优化温度、风速、载料量、热烫预处理时间等工艺条件。试验结果表明,适当的桑叶热烫时间能够提升桑叶的复水性,烘干温度和载料量是影响桑叶干燥进程的主要因素。优化的工艺条件为:热烫预处理时间2.0 min,载料量0.57 kg/m~2,温度65℃,风速3.0 m/s。对优化的工艺条件进行验证试验,桑叶干燥耗时1.0h,干燥系数为0.059 7,复水值为3.18,说明采用热风平穿流设备及上述优化工艺条件对桑叶进行低温干燥加工,干燥效率较高,并能较好地保持桑叶的品质。     

白族乳扇加工制作历史与发展探讨

邓川牛作为大理白族地区著名的乳用黄牛品种,对当地的饮食文化产生了深远的影响,衍生出了乳扇这一白族独具特色的乳制品。通过对白族传统乳扇加工制作进行回顾,对现阶段乳扇加工生产中存在的问题进行分析,并提出相关建议,以期乳扇产业能够健康持续发展,在乡村振兴战略中发挥作用。     

洱源县邓川乳扇生产加工技术概述

乳扇是洱源县邓川地区特有的民族乳制品,属硬质奶酪,具有营养价值高,运输、贮存、食用方便,有效期较长等特点。对于缺乏乳品机械化和规模化加工条件的奶牛养殖地区,加工销售乳扇是连接养殖者和消费者最直接、最有效的途径。为实现程序规范化、生产加工标准化、质量安全化、奶牛养殖及乳扇加工效益高效化,洱源县特制定了《洱源县邓川乳扇生产加工技术标准》。本文就此标准作一概述,以期推动洱源县邓川乳扇生产加工逐步向科学化、标准化及规范化的方向发展。     

乳扇制品中乳杆菌分离鉴定及其发酵性能试验

乳扇是云南大理白族的一种传统乳制品，本文对乳扇及其酸乳清样品中的乳杆菌进行调查，由３６份样品中共分享到１１６株乳杆菌，鉴定出２１种（亚种），其中干酷乳杆菌、德氏乳杆菌、发酵乳杆菌及植物乳杆菌等四种７３％，确认是乳扇制品中的优势种群。同时对分离菌株进行发酵性能测定，发现部分菌株有较好的产酸产香性能。     

Relationship between pH and Temperature in the Ruminal Fluid of Cows, Based on a Radio-Transmission pH-Measurement System

To assess the relationship between pH and temperature in the ruminal bottom fluid, circadian changes were monitored using cows fed a control diet (C diet) or a rumen acidosis-inducing diet (RAI diet) by using a wireless radio-transmission pH- measurement system. These two parameters were measured simultaneously at 10-min intervals on day 14 after commencement of feeding. Compared to the mean ruminal pH for 60 min immediately after the morning feeding (0 hr), significantly lower pH was noted 3-13 hr later (P<0.05) and 4-19 hr later (P<0.01) in cows fed the C and RAI diets, respectively, although the reduction in the latter was much higher than that in the former. In contrast, significantly higher ruminal temperature was found at 8 and 12-14 hr later (P<0.05) and 6, 8, and 10-19 hr later (P<0.01) in cows fed the C and RAI diets, respectively. A significant negative correlation was observed between the lowest ruminal pH and its corresponding ruminal temperature in cows fed the C and RAI diets (r=-0.722 and -0.650, P<0.01, respectively), suggesting active fermentation and volatile fatty acid production in the rumen. However, ruminal pH profiles may not be predictable by measuring only ruminal temperature because decreases in ruminal pH were preceded by increases in ruminal temperature, and circadian changes in pH and temperature were associated with ruminal fermentation.     

长江下游农区金花菜叶蛋白提取工艺优化及关键参数特征

为改进和优化金花菜(Medicago polymorpha)叶蛋白提取的工艺环节,并提高叶蛋白提取率及提取物纯度等参数指标,本研究选择长江下游农区广泛种植的金花菜为原料,通过设置较为合理科学的料液比、提取温度、加热时间、pH以及提取剂(酸)种类进行叶蛋白提取单因素试验。结果表明:各单因素试验最佳参数分别为料液比1∶3、提取温度70℃、加热时间15 min、pH 4、提取剂(酸)为盐酸。基于清洁安全生产角度,选择了单因素试验中提取指标同样较高的柠檬酸作为提取剂,设置了料液比、pH及提取温度的3因素3水平响应面试验,发现影响叶蛋白提取率的因素依次为pH、提取温度、料液比。得到最佳提取工艺:料液比1∶3、pH 4.1、提取温度72℃,相应的叶蛋白提取率为49.63%,提取物纯度为56.87%。本研究优化的技术工艺及相关参数指标可为农区豆科草类植物多元化利用及叶蛋白工业化生产提供一定的技术支撑和相关借鉴。     

鸭肉中组织蛋白酶B的特性研究

从樱桃谷肉鸭腿肌中提取组织蛋白酶B,研究了pH值、温度、蛋白酶激活剂和抑制剂对其酶活的影响。结果表明:组织蛋白酶B的最适反应pH值为5.5,最适反应温度为40℃,在30℃下和pH 5.0～5.5范围内有较好的稳定性。激活剂二硫苏糖醇(DTT)和L-半胱氨酸(L-cys-teine)对组织蛋白酶B有一定的激活作用;抑制剂E-64对组织蛋白酶B有明显抑制作用;金属蛋白酶抑制剂已二胺四乙酸(EDTA)和丝氨酸蛋白酶抑制剂苯甲基磺酸氟(PMSF)对组织蛋白酶B无抑制作用。     

冷却排酸期间牛胴体温度与pH的变化及其对牛肉汁液渗出性的影响

为研究牛胴体温度与pH变化规律对牛肉汁液渗出性的影响,本研究对100头秦川牛胴体的前部(脖肉)、中部(外脊)、后部(臀肉)在屠宰后冷却排酸过程中温度与pH随屠宰后时间的变化进行了同步跟踪测定,并对冷却排酸后相应部位肉表面的汁液渗出性加以分析。结果表明,中部胴体温度下降速率最高,分别是前部和后部的1.75和1.45倍。前部胴体pH下降速率最小,中部和后部胴体下降速率分别是前部胴体的6.56和4.88倍,最终pH为前部胴体>中部胴体>后部胴体。而pH下降至6时的温度与汁液渗出性之间具有极好的正相关性,其线性回归方程拟合度R2均达到0.8以上。pH为6时的温度均对汁液渗出性有明显影响。结果提示,胴体温度与pH的相对变化会对肉的持水力产生明显影响。     

Theileria parva: In Vitro Studies on the Effects of Holding Temperature,pH and Medium on Sporozoite Infectivity

The effects of holding temperature, pH and medium on the infectivity of Theileria parva sporozoites were investigated using an in vitro infectivity assay. The sporozoite infectivity lasted for 72 h at a holding temperature of 4 C but for only 24 h at 24 degrees C. Sporozoite infectivity was found to be sensitive to pH variations and sporozoites were most infective between pH 7 and pH 8. There was a significant loss in infectivity at pH 5 and infectivity was almost totally abolished at pH 9. Theileria parva sporozoites are usually held and manipulated in Eagle's minimum essential medium (MEM) with Earles' salts. In this study. Leibovitz-15 supplemented with 15% fetal bovine serum gave a significantly better infectivity than Eagle's MEM (3.8 log units versus 1.0 log units) or any other medium. The importance of proper management of the T. parva sporozoite environment in the laboratory or field is emphasized by the findings in these studies and might also explain some of the failures of vaccination when the pH of the holding medium was allowed to deteriorate.     

Screening and Identification of the Cellulase-producing Fungus

In order to isolate the strains which could degrade fiber from the straw,the straw samples were inoculated on the potato agar medium and cultured at room temperature.The isolating strains were inoculated on the cellulose-congo red agar medium,the strains were screened that could produce bigger cellulose-decomposing zone.It was identified by morphological characteristics and molecular biological methods,and characterization of cellulase was analyzed preliminarily.The results showed that the fungus was Aspergillus niger,it could grow at room temperature,and the H/C was 7.64.The highest cellulase activity reached 42.18 U/mL when cultivated at 20 ℃ for 5 days.The optimum pH was 7.0 and the optimum reaction temperature was 20 ℃,the relative cellulase activity still retained above 90% at 20 to 40 ℃ or pH 6.0 to 8.0 for 1 h.The Aspergillus niger was a cold-adapted cellulaseproducing strain,it had strongger producing cellulase ability,and was tremendous potential valuable for microbial development.     

产纤维素酶真菌的筛选与鉴定

为从秸秆中分离出能够降解纤维的菌株,试验采取秸秆样品接种马铃薯琼脂培养基,在室温环境下培养,取分离菌接种纤维素刚果红琼脂培养基,筛选能形成较大降解圈的细菌,并进行形态学和分子生物学鉴定,测定其纤维素酶性质。结果表明,经分子生物学鉴定,筛选菌为黑曲霉菌,该菌在室温环境能够生长,菌株降解圈直径(H)与菌落直径(C)的比值(H/C)为7.64。筛选菌在20 ℃环境下培养5 d酶活达到最高值,为42.18 U/mL。纤维素酶最适pH为7.0,最适反应温度为20 ℃,在20~40 ℃或pH 6.0~8.0环境下作用1 h,相对酶活力仍保持在90%以上。综上所述,本试验分离的黑曲霉菌株是低温产纤维素酶菌株,产酶能力较强,具有潜在的开发价值。     

pH值对海藻酸丙二醇酯溶液流变特性的影响

作为一种增稠剂,海藻酸丙二醇酯广泛应用于乳制品或乳饮料中。采用AR-G2流变仪,通过稳态流动、应变扫描、频率扫描、动态黏弹性温度扫描及动态黏度温度扫描等实验研究pH值对海藻酸丙二醇酯溶液流变特性的影响。结果表明:pH值的增加使海藻酸丙二醇酯溶液的黏度降低,同时使其黏弹性与复合黏度降低,损耗正切增加。另外,pH值低于7时,海藻酸丙二醇酯溶液的剪切稀化程度减弱,pH值高于7时,溶液的剪切稀化程度增强。同时,pH值影响海藻酸丙二醇酯溶液的黏度及黏弹性的温度效应。     

Assessment of the impact of collection temperature and sampler design on the measurement of exhaled breath condensate pH in healthy horses

The pH measurement of exhaled breath condensate (EBC) may provide a non-invasive method of assessing the lower airways of horses but the methodology used may influence findings. The aim of this study was to investigate the effect of two sampling devices and three methods of condensation surface cooling (ethanol slush, -100°C; dry ice, -75°C; water ice, 0°C) on EBC pH. Each method was tested 30 times using six healthy ponies. Sample pH was determined before and after de-aeration with argon for 10 min. Sampler design was found to significantly affect pH. Samples collected as a liquid had a significantly higher pH than samples frozen during collection (P<0.05). De-aeration resulted in significantly higher pH (P<0.05) with less variation. This study has shown that device design and condensation surface temperature will influence EBC pH, which will prevent a direct comparison of results when different methodologies are used.     

当归炭疽病菌的生物学特性研究

本试验利用常规方法研究了当归炭疽病菌(束状炭疽菌Colletotrichum dematium)的生物学特性和营养利用能力,为明确当归炭疽病的发生流行规律提供了依据。结果表明,菌落生长和孢子萌发最低温度和最高温度为10 ℃到35 ℃,最适为25 ℃;在pH 5~11间菌落可以生长,最适pH为11;在pH 8~11间产孢,最适pH为10,但中性有利于孢子萌发;该菌对碳氮源利用范围广,但甘露糖、D-半乳糖和氯醛糖抑制其生长;菌落生长和孢子萌发对光照不敏感;相对湿度95%以上分生孢子能萌发,水中萌发率显著高于其他湿度条件(P<0.05),蔗糖能够促进孢子的萌发,但马铃薯汁液抑制其萌发。