低酸度酒精阳性水牛乳制备干酪的可利用性研究

为探索低酸度酒精阳性水牛乳的可利用性,以正常水牛乳与低酸度酒精阳性水牛乳为原料,生产水牛乳硬质干酪,分析所制备的干酪理化性质的差异。结果表明:低酸度酒精阳性水牛乳制作的干酪与正常水牛乳加工的干酪理化性质并不存在显著差异(P>0.05),低酸度酒精阳性水牛乳完全可以用于水牛乳干酪的加工。     

低酸度酒精阳性乳用于酸奶生产的探讨

在乳品生产中,常遇到低酸度酒精阳性乳,若作为奶粉原料,将影由其溶解性。而用作酸奶原料,对产品质量尚无影响,为此,本文对该问题进行了试验性探讨。     

酒精阳性水牛乳乳成分及理化性质的研究

本研究连续一年观测了摩拉水牛、尼里-拉菲水牛、一代杂水牛和三品杂水牛4个种水牛乳64%的不同季节的酒精阳性发生率、乳成分、理化性质,并比较了酒精阳性乳、阴性乳与乳样总体的差异。结果表明,纯种河流型水牛(摩拉水牛、尼里-拉菲水牛)乳酒精阳性率低于两个杂交水牛(三品杂水牛、一代杂水牛),各品种水牛乳均以2~4月和8~10月的阳性率为最高。低酸度酒精阳性乳(12~18oT)占据了酒精阳性乳的52.9%~64.1%。酒精阳性乳的乳蛋白、乳固体、非脂乳固体、酸度均显著高于阴性乳和乳样总体平均值,但冰点低于乳样总体平均值。可见不同品种水牛乳不能用同一酒精浓度进行检验;酒精阳性率可反映水牛应激或营养状况;较高的乳蛋白、非脂乳固体、总乳固体、酸度以及较低的冰点是酒精阳性水牛乳的特征;酸度和冰点是品种间酒精阳性率差异的主要因素。     

关于羊奶酒精反应阳性乳的研究

一、前言乳的酒精试验是我国普遍应用的一种简单、快速,而且比较可靠的检测牛乳新鲜度的方法,它可以反映乳中酸度的高低,亦可表达出细菌污染和繁殖的程度,因此,酒精试验能够     

低，中度近视眼的发病机理及其防治

青少年低、中度近视眼在我国的发生率较高,已引起社会的普遍关注。根据发生近视的年龄,有在14岁以下的早发性近视,发生于15～19岁的迟发性近视,以及20岁以后发生的成年人近视。 低、中度近视的发生有一定的遗传因素,但更重要的是环境因素。在近视眼的发病机理中,主要是晶状体屈折力增加和眼轴的延长。晶状体屈折力增加是由于睫状肌收缩增强或睫状肌弛缓障碍所致。由于近距离工作过久,持续性睫状肌收缩可促进近视的形成。任何可以放松调节减少晶状体屈折力的措施都有利于预防近视,利用低度凸透镜看近(近雾视法)被认为是一安全易行的办法,渐进多焦点眼镜可成为今后预防近视的理想用品。各种创伤性近视眼手术都不适于治疗青少年近视,OK镜矫治也应当慎重,至今唯一有效可靠的近视眼矫正方法仍然是配戴合适的眼镜以增进视力。     

温度对原料乳酒精试验结果影响的研究

酒精检验是为观察鲜乳的抗热性而广泛使用的一种方法。本试验通过酒精的脱水作用,确定酪蛋白的稳定性。结果表明：新鲜牛乳对酒精的作用表现出相对稳定;而不新鲜的牛乳,其中蛋白质胶粒已呈不稳定状态,当受到酒精的脱水作用时,则加速其聚沉。此法可以验验出鲜乳的酸度,以及盐类平衡不良乳、初乳、末乳及因细菌作用而产生凝乳酶的乳和乳房炎乳等。     

原料乳蛋白质含量及酸度多功能快速检验试剂盒的研制

将原料乳蛋白质含量测定技术和酸度测定技术试剂盒化。采用甲醛滴定法测定原料乳蛋白质含量、酸碱滴定法测定原料乳酸度,确定试剂盒的组分,并对试剂盒的符合率、重复性、稳定性等进行研究。该试剂盒由4种试剂组成,与凯氏定氮法和酸碱滴定法的符合率为100%,重复性良好,密封干燥处保存540d各项性能仍然很好。该试剂盒既可同时检测各种原料乳蛋白质含量和酸度,也可检测各种消毒乳和酸牛乳的蛋白质含量。     

乳与乳制品的酸度测定不确定度分析

本文通过建立采用GB 5413.34-2010食品安全国家标准乳和乳制品酸度的测定检验方法测定的不确定度评定的模型,对检测过程中可能引入的不确定度来源进行了分类和量化,较为全面的评定了各个不确定度分量,并提出了应用该方法检测的不确定度评定结果.     

葡萄黄化病的发病机理及防治方法

葡萄黄化病又称葡萄黄叶病,是一种生理性病害,主要发生在我国西北部和滨海盐碱地带.根据作者多年的栽培经验,将葡萄黄化病的发生机理和防治方法阐述如下,以供有关生产和研究单位参考.     

乳和乳制品中残留抗生素的检测方法

论述了牛奶中残留抗生素的原因及危害性，列举了目前世界上较为流行的牛奶抗生素检测方法，并介绍了其检测原理。     

正项级数审敛法的研究进展

正项级数的审敛法在级数的审敛法中占有十分重要的地位.常见的关于正项级数的审敛法共有7种,分别是比较判别法,达朗贝尔判别法,柯西判别法,拉阿伯判别法,高斯判别法,柯西积分判别法和对数判别法.介绍正项级数审敛法的最新研究进展情况,与常见的审敛法作了比较,给出对数判别法的极限形式.     

Short communication: Prediction of milk coagulation and acidity traits in Mediterranean buffalo milk using Fourier-transform mid-infrared spectroscopy

Milk coagulation and acidity traits are important factors to inform the cheesemaking process. Those traits have been deeply studied in bovine milk, whereas scarce information is available for buffalo milk. However, the dairy industry is interested in a method to determine milk coagulation and acidity features quickly and in a cost-effective manner, which could be provided by Fourier-transform mid-infrared (FT-MIR) spectroscopy. The aim of this study was to evaluate the potential of FT-MIR to predict coagulation and acidity traits of Mediterranean buffalo milk. A total of 654 records from 36 herds located in central Italy with information on milk yield, somatic cell score, milk chemical composition, milk acidity [pH, titratable acidity (TA)], and milk coagulation properties (rennet coagulation time, curd firming time, and curd firmness) were available for statistical analysis. Reference measures of milk acidity and coagulation properties were matched with milk spectral information, and FT-MIR prediction models were built using partial least squares regression. The data set was divided into a calibration set (75%) and a validation set (25%). The capacity of FT-MIR spectroscopy to correctly classify milk samples based on their renneting ability was evaluated by a canonical discriminant analysis. Average values for milk coagulation traits were 13.32 min, 3.24 min, and 39.27 mm for rennet coagulation time, curd firming time, and curd firmness, respectively. Milk acidity traits averaged 6.66 (pH) and 7.22 Soxhlet-Henkel degrees/100 mL (TA). All milk coagulation and acidity traits, except for pH, had high variability (17 to 46%). Prediction models of coagulation traits were moderately to scarcely accurate, whereas the coefficients of determination of external validation were 0.76 and 0.66 for pH and TA, respectively. Canonical discriminant analysis indicated that information on milk coagulating ability is present in the MIR spectra, and the model correctly classified as noncoagulating the 91.57 and 67.86% of milk samples in the calibration and validation sets, respectively. In conclusion, our results can be relevant to the dairy industry to classify buffalo milk samples before processing.     

乳及乳制品中抗生素类兽药残留快速检测技术

抗生素等兽药残留物分析是个十分复杂的技术问题，介绍了按不同目的和要求对抗生素等兽药残留物进行的分级检测的策略，并对目前国内外正在应用或开发的快速检测技术进行了介绍。     

羊奶干酪加工过程中酸度及乳成分变化规律的研究

以西农莎能奶山羊的新鲜奶为原料,添加ＥＺＡＬ ＭＡ０１１乳酸发了剂,研究羊奶干酪加工过程中酸度和乳成分变化规律,以及不同凝乳酶对它们的影响。结果表明,羊奶干酷加工过程中,酸度缓慢上升,而不同凝乳酸对酸度无显著影响;从鲜奶至消毒奶,乳成分基本不变;加发酵剂后,乳脂和乳蛋白基本不变,乳糖明显下降;加凝乳酶后各种乳成分显著下降。     

气相色谱-质谱/质谱法测定牛奶和奶粉中的肌醇

建立了一种用GC-MS/MS测定牛奶和奶粉中肌醇质量分数的方法。奶粉样品溶于水后,牛奶直接称量,试样中的肌醇用水和乙醇提取后,与硅烷化试剂衍生,正己烷提取,用GC-MS/MS测定。该方法回收率为86.9%~108.6%,相对标准偏差为3.6%,最低检出限为0.1 mg/kg,且检测结果准确可靠,重复性好,灵敏度高,可进行牛奶和奶粉中肌醇的检测。     

Performance of blue-yellow screening test for antimicrobial detection in ovine milk

Drug residues in milk are important because of public health and industrial implications. The detection limits of 25 antimicrobial agents were determined by the blue-yellow screening method in ovine milk. For each drug, 8 concentrations were tested on 20 ovine milk samples from individual ewes in midlactation. Detection limits determined by means of logistic regression were below European Union maximum residue limits (EU-MRL) for penicillin G (3 to 4 μg/kg), ceftiofur (96 to 107 μg/kg), framycetin (720 to 781 μg/kg), neomycin (915 to 1,084 μg/kg), and tylosin (44 to 51 μg/kg). Detection limits for ampicillin (5 to 6 μg/kg), cloxacillin (33 to 42 μg/kg), cefoperazone (73 to 82 μg/kg), cefalexin (160 to 202 μg/kg), gentamycin (355 to 382 μg/kg), streptomycin (3,063 to 3,593 μg/kg), tilmicosin (109 to 131 μg/kg), erythromycin (444 to 522 μg/kg), spyramicin (1,106 to 1,346 μg/kg), sulfadimethoxine (101 to 119 μg/kg), sulfathiazole (122 to 151 μg/kg), sulfamethazine (309 to 328 μg/kg), sulfanilamide (1,750 to 2,674 μg/kg), tetracycline (233 to 257 μg/kg), oxytetracycline (398 to 501 μg/kg), doxycycline (323 to 419 μg/kg), chlortetracycline (3,331 to 3,989 μg/kg), danofloxacin (4.7 to 5.5 mg/kg), enrofloxacin (41 to 46 mg/kg), and flumequin (63 to 71 mg/kg) were higher than the EU-MRL. Although the blue-yellow method showed improved sensitivity compared with other tests studied in ovine milk, the performance of screening methods for detecting antimicrobial agents in milk of this species should be improved.     

牛奶中过氧化氢快速检测试纸条的研制

当前,食品安全问题日益突出,其中乳制品安全问题也备受关注,为了防止牛奶变质,不法经营者向牛奶中掺入过氧化氢,对消费者健康造成巨大威胁。传统的过氧化氢检测方法复杂且耗时较长,为满足现场快速、准确检测过氧化氢残留的需求,本研究利用酶促反应原理,将含有1g/L的四甲基联苯胺(TMB)和10μg/mL的辣根过氧化物酶(HRP)混合溶液作为显色剂,并加入适当的保护剂,以定量滤纸为载体,经真空干燥并加工制成过氧化氢快速检测试纸条。该试纸条能够在10秒钟内对牛奶中的过氧化氢残留进行半定量检测,最低检出限达到0.5mg/L,并且操作简单,价格低廉,十分适用于奶制品厂和基层奶站的现场检测。     

原料乳危害及控制措施研究

分析了原料乳的生物性、化学性和物理性危害，针对各种危害的来源提出相应的控制措施．为原料乳HACCP体系的建立提供参考。     

Evaluation of a microbiological indicator test for antibiotic detection in ewe and goat milk

Antibiotics are widely used for therapeutic and prophylactic purposes in dairy animals. The presence of residual antibiotics in milk could cause potentially serious problems in human health and have technological implication in the manufacturing of dairy products. The aim of this study was to evaluate Delvotest Accelerator (DSM Food Specialties, Delft, the Netherlands), a new system for a fully automated microbial test to detect antibiotic residues in ewe and goat milk. Forty-three samples of raw, whole, refrigerated bulk-tank milk samples (22 of ewe milk and 21 of goat milk) were analyzed during the whole lactation period. Four concentrations of 4 antibiotics were diluted in milk: penicillin G at 1, 2, 3, and 4 μg/L; sulfadiazine at 25, 50, 100, and 200 μg/L; tetracycline at 50, 100, 200, and 400 μg/L; and gentamicin at 25, 50, 100, and 200 μg/L. The detection limit of the Delvotest Accelerator was calculated as the range of antibiotic concentrations within which 95% of positive result lie. The range of detection limit of penicillin G and sulfadiazine was easily detected by Delvotest Accelerator at or below the European Union maximum residue limits, both for ewe and goat milk samples. In contrast, the system showed a lower ability to detect tetracycline and gentamicin both for ewe and goat milk samples. Very low percentages of false-positive outcomes were obtained. Lactation phase did not seem to be a crucial factor affecting the ability of the Delvotest Accelerator to detect spiked milk samples. A higher detection ability was observed for goat milk samples compared with ewe milk samples. A negative correlation between the percentage of positive milk samples detected and milk fat, protein, and lactose contents was observed for gentamicin only.