市售纯牛奶中抗菌药物残留的检测

为了解山西省太谷县所销售纯牛奶中抗菌药物残留的情况，随机采购此种牛奶50份，分别采用TTC法、微生物检测法和酶标免疫分析法对样品进行抗生素残留检测，以农业部2001年发布的“无公害食品”牛奶中不得检出抗生素为判定标准。TTC法检测出4份阳性，3份可疑，阳性率为8％，可疑率为6％；微生物法检测出青霉素类残留阳性5份，阳性率为10％；酶标免疫分析法检测出四环素类阳性4份，阳性率为8％，链霉素残留阳性11份，阳性率为22％，磺胺二甲嘧啶检测结果全部为阴性。调查结果显示，市售消毒纯牛奶中有部分存在抗菌药物残留。     

色谱技术在牛奶中抗生素残留检测方面的应用

由于近期发生的三聚氰胺奶粉事件,目前牛奶及奶制品的安全问题是国家及社会关注的焦点问题之一。因而奶制品中有毒有害物质检测技术也成为当前食品检测领域的研究热点。针对抗生素残留问题是牛奶及制品安全方面的一大突出问题,本文以抗生素类别为划分综述了近年来色谱技术及其与质谱联用分离分析技术在奶制品中抗生素类残留检测中的应用,主要包括气相色谱、液相色谱及色谱质谱联用技术等。     

乳与乳制品抗生素残留及其在病牛乳中持续时间的探讨

1986年6～7月对南京、无锡、苏州、常州、徐州、淮阴、泰州、盐城等市的10个乳牛场使用抗生素的情况和乳与乳制品中抗生素残留量及其持续时间进行了探讨。結果:各乳牛场均使用青霉素、链霉素等抗生素药物治疗乳牛的各种疾病。应用TTC法检测乳与乳制品中抗生素残留量的检出率时,生奶3.6%,消毒牛奶11.48％、奶粉39.58％;青链霉素水剂在常量下不论给药途径如何,奶中残留持续时间都不超过48小时。病侧乳室灌注抗生素后,在邻室分泌出的乳中不存在抗生素残留;肌肉注射抗生素,奶中残留经24小时就呈阴性,而乳室灌注法奶中的残留要经48小时才转阴性,因此提倡肌注法给药。     

乳品中多种抗生素残留胶体金检测方法研究

研究用于牛奶和奶粉中多种抗生素残留同时检测的胶体金免疫层析试纸条。基于胶体金免疫层析技术,搭建抗原包被体系和胶体金标记抗体体系,优化检测方法,考察胶体金快速检测试纸条的检测灵敏度、特异性、准确度和实际样本适应性。试纸条可同时检测卡那霉素、红霉素、林可霉素3种药物在牛奶、奶粉中的残留,检测限分别为50.0,20.0和75.0μg/L,假阳性率和假阴性率均为0,样本无需前处理,检测操作简单,10 min内实现3种药物同时检测。采用胶体金试纸条和液相色谱串联质谱法对20份牛奶和奶粉盲样进行比对试验,阳性样品全部检出,2种方法测定结果一致。建立的胶体金免疫层析技术及试纸条检测准确可靠,适用于现场大批量样本的快速检测和筛选。     

食品(乳品)中存在抗生素残留的风险及其控制

介绍了食品中存在抗生素残留的风险,阐明了最大残留极限(MRL)的技术学及其法规基础,说明了抗生素转移到牛奶中的原因、过程及其残留,介绍了牛奶中抗生素残留的4种检测方法.分析了牛奶受抗生素残留污染的风险;介绍了通常的预防措施和抗生素的使用控制,提出了戴尔沃10点计划.     

牛奶中抗生素残留量三种检测方法的比较

<正> 牛奶抗生素残留是涉及细菌耐药、涉 及人类健康的公共卫生问题,因而越来越受到各界人士的关注。国际上发达国家对牛奶抗生素的最大残留量和检测方法都有严格而具体的规定,而我国虽有抗生素的国标检测方法,但在国家食品卫生标准中牛奶的抗生素残留允许量仍未有具体规定。我国不少大型牛奶公司在涉及产品进出口时,需采用国际认可的检测方法和允许标准来检测和评价产品。抗生素残留检测方法是否方便、快速、敏感、准确越来越受到各生产商及     

牛奶中抗生素残留的几种常用检测方法

<正> 随着奶牛饲养业的发展,抗生素在预防和治疗奶牛疾病方面得到广泛的应用。生鲜牛奶中抗生素的来源主要是:第一,治疗泌乳期病牛时使用的抗生素会从奶牛体内移行到乳腺残留进入牛奶中,资料表明治疗后的奶牛,其挤出的牛奶5天内都有抗生素残留;其二,为了预防奶牛疾病并提高产量,在奶牛饲料中添加抗生素也会造成牛奶中抗生素的残留;第三,由于牧场管理不善,挤奶、储奶没有严格的卫生制度和配套的设施,人为添加或造成牛奶抗生素的污染。 牛奶中含有抗生素,不仅对人的健康造成很大的危害,而且对乳品加工企     

市售酸奶中乳酸菌对青霉素的药敏性试验

抗生素在乳制品行业中广泛应用,不可避免地造成牛奶中残留抗生素。抗生素残留不仅危害人类健康,同时牛奶中抗生素残留会影响奶制品的品质,如果用含抗生素的奶做酸奶或乳酪等发酵制品,则残留在其中的抗生素会抑制细菌的发酵,使产量和质量降低。本文就是针对酸奶中有青霉素存在的情况下,利用分光光度法检验乳酸菌是否具有耐药性极其耐药程度分析。结果表明:10份检验样品中,8份样品中所分离的乳酸菌对青霉素类有耐药性;而样品不同,乳酸菌对青霉素的耐药性也不同。     

牛奶中抗生素残留的微生物检测方法应用分析

牛奶因其高营养价值得到了人们的青睐,但牛奶抗生素残留问题受到了社会各界的广泛关注。本文使用微生物检测方式分析牛奶内抗生素的残留,旨在强化原料、产品质量检测,为保护居民身体健康提供有效参考意见。     

浙江省部分地区鲜牛奶与消毒牛奶中氯霉素、四环素类抗生素残留的调查及检测分析

对浙江省范围内的鲜牛奶与消毒牛奶中氯霉素、四环素类兽药残留量进行专项调查,并用酶标免疫试剂盒(德国拜发试剂盒)对鲜牛奶与消毒牛奶中氯霉素、四环素类兽药残留进行检测。共调查了鲜牛奶和消毒牛奶各140批次,涉及53个厂家,10个地区,合格为132和136批次,不合格为8和4批次,合格率为94.3%和97.1%。建议有关卫生管理部门将抗生素检测纳入常规检测项目,以保证广大消费者饮用安全卫生的绿色食品。同时应特别加强对私营企业的管理和产品质量监测。     

PREVALENCE OF ANTIMICROBIAL RESIDUES IN MILK AND DAIRY PRODUCTS IN THE STATE OF KUWAIT

ABSTRACT

Approximately, 1,000 locally produced and imported milk and dairy product samples were collected at different seasonal periods from different farms and retail outlets in Kuwait, and screened for the presence of four antimicrobial residues (beta‐lactams, tetracyclines sulfonamides and chloramphenicol) using Charm II system. Results indicated that 29.1% of the analyzed local fresh milk samples were above the maximum residue level (MRL) for tested residues with tetracycline as predominant residue. The prevalence of antimicrobial residues in imported pasteurized milk samples (5.4%) was higher than that of local pasteurized milk samples (3.4%). No residues were detected in powdered and condensed milk samples imported from the European Union (EU) countries with the exception of tetracyclines. Results also showed that 9.4% of the analyzed imported cheese samples were above the MRL for tested residues, while tested ice cream samples were negative for antimicrobial residues. The significant presence of antimicrobial residues, particularly chloramphenicol, in raw and pasteurized milk, clearly implies the misuse of antimicrobial drugs in animal farms in Kuwait and neighboring countries, and implies the need for stricter regulations on antimicrobial drug usage in the dairy industry.

PRACTICAL APPLICATIONS

This article addresses the generation of a baseline data on the current presence of four antimicrobial residues in locally produced and imported milk and dairy products in the state of Kuwait. The outcome of this study will provide valuable baseline information for local governmental authorities for effective monitoring for the use and misuse of agricultural antimicrobial drugs. Such data will also be important for other Gulf Cooperation Council countries, because such countries share similar farming practices and import comparable foodstuffs.

     

Proteolysis during ripening of Manchego cheese made from raw or pasteurized ewes' milk. Seasonal variation

Changes in nitrogen compounds during ripening of 40 batches of Manchego cheese made from raw milk (24 batches) or pasteurized milk (16 batches) at five different dairies throughout the year were investigated. After ripening for six months, degradation of p-kappa- and beta-caseins was more intense in raw milk cheese and degradation of alpha(s2)-casein in pasteurized milk cheese. Milk pasteurization had no significant effect on breakdown of alpha(s1)-casein. Hydrophobic peptide content did not differ between raw and pasteurized milk cheese, whereas hydrophilic peptide content was higher in raw milk cheese. There were no significant differences between seasons for residual caseins, but hydrophobic peptides were at a higher level in cheese made in autumn and winter and hydrophilic peptides in cheese made in winter and spring. Raw milk cheese had a higher content of total free amino acids and of most individual free amino acids than pasteurized milk cheese. The relative percentages of the individual free amino acids were significantly different for raw milk and pasteurized milk cheeses. The relative percentages of Lys and lie increased, while those of Val, Leu and Phe decreased during ripening. There were also seasonal variations within the relative percentages of free amino acids. In raw milk cheeses, Asp and Cys were relatively more abundant in those made in autumn, Glu and Arg in cheeses made in winter, and Lys and Ile in cheeses made in spring and summer. Biogenic amines were detected only in raw milk cheese, with the highest levels of histamine, tryptamine and tyramine in cheeses made in spring, winter and spring, respectively.     

PREVALENCE OF ANTIMICROBIAL RESIDUES IN PREPROCESSED AND PROCESSED COWS' MILK IN TRINIDAD

The prevalences of antimicrobial residues were determined in cows' bulk raw milk from 16 collection centers, in pasteurized milk obtained from sale outlets, and in raw, pasteurized and sterilized milk in the processing line of a plant in Trinidad. The Delvotest SP 5 Pack test kits were used to detect the antimicrobial residues in milk. Thirty-one (10.3%) of 300 bulk milk samples contained antimicrobial residues with penicillin responsible for 90.3% of all the positive samples which originated from 8 (50.0%) of the 16 collection centers. The prevalence of residues in pasteurized milk was 21.3% compared to 8.3% detected in sterilized milk. The difference was not statistically significant (P ± 0.05; X²). Pasteurized milk obtained from sale outlets but originating from two other processing plants had antimicrobial residue prevalence of 0% and 8.3%, respectively. It is concluded that the presence of antimicrobial residues in raw and processed milk in Trinidad could be of public health and economic significance .     

Drug resistance and lecithinase activity of Yersinia enterocolitica isolated from buffalo milk

Two-hundred-and-seven samples of raw buffalo milk and 60 samples of pasteurized buffalo milk were screened for presence of Yersinia enterocolitica. The prevalence of Y. enterocolitica was found to be 24.1% in raw milk, however, no isolation could be made from the pasteurized milk samples. Cold enrichment in trypticase soy broth and alkali treatment methods were followed in this study. The majority of the isolates (62%) were found sensitive to all the antibiotics used and only a few (16%) were resistant to two or more than two antibiotics. The incidence of Y. enterocolitica showed seasonal variations. Incidence was much higher (25-50%) during the winter season as compared to the summer (0-17%). The incidence of lecithinase production was high (40-50%) in Yersinia isolates resistant to one or two antibiotics.     

High Pressure Treatment of Milk and Effects on Microbiological and Sensory Quality of Cheddar Cheese

The effect of cycled high pressure treatment of milk on the yield, sensory, and microbiological quality of Cheddar cheese was investigated. Cheddar cheeses were made from pasteurized, raw, or pressure treated milk according to traditional methods. Flavor scores from trained dairy judges were not different for pasteurized and pressurized milk cheeses (P≤0.05). Percent moisture and wet weight yields of pressure treated milk cheeses were higher than pasteurized or raw milk cheeses (P≤0.05). Microbiological quality of pressurized milk cheeses was comparable to pasteurized milk cheeses. Texture defects were present in pressurized milk cheeses and were attributed to excess moisture. High pressure treatment of milk shows promise as an alternative to heat pasteurization prior to cheesemaking.     

Impact of CO2 addition to milk on selected analytical testing methods

The addition of CO2 to raw milk and dairy products controls the growth of psychrotrophic bacteria at refrigeration temperatures. The objective of this study was to determine the effects of dissolved CO2 in milk on the performance of four important routine testing methods: antibiotic residue test, freezing point test, infrared milk component analysis, and alkaline phosphatase test. Raw or pasteurized whole milk was carbonated at <4 degrees C to contain approximately 0 (control), 200, 400, 600, and 1000 ppm of CO2. The addition of CO2 to raw milk up to 1000 ppm had no effect on the performance of the three antibiotic (beta-lactams) residue tests: IDEXX SNAP, Charm II Sequential Tablet, and Delvo-P Ampule. Milk freezing point decreased linearly with increasing concentration of dissolved CO2, from -0.543 degrees H (control) to -0.595 degrees H (1000 ppm). Carbonation to 1000 ppm decreased milk pH (measured at 38 degrees C) from 6.61 (control) to 6.15 (1000 ppm). The effects of CO2 on milk freezing point and pH were reversible upon removal of dissolved CO2. Increased CO2 levels in milk changed the infrared absorption spectrum of milk and caused the corrected lactose readings to decrease and the corrected fat B readings to increase. For the alkaline phosphatase tests, 0 (none), 0.05, 0.1, and 0.2% raw milk were deliberately added to pasteurized milks of six levels of carbonation (0 to 1000 ppm). The addition of CO2 did not influence the ability of Fluorophos, Charm PasLite, and Scharer Modified Rapid tests to differentiate between a pasteurized milk and a pasteurized milk with raw milk contamination.     

PAHs concentration in heat-treated milk samples

In this study the presence of residual levels of Polycyclic Aromatic Hydrocarbons (PAHs) in milk samples from Calabria was evaluated. A comparative analysis of PAHs concentrations was conducted on raw, pasteurized, UHT semi-skimmed and whole milk.Quantitative determination of PAHs was performed by HPLC using a fluorescence detector and analysis in HPLC-MS was conducted to confirm the presence of these compounds.Residual levels of PAHs were found in all milk samples analyzed, showing higher concentrations in pasteurized and UHT milk than in raw milk samples.The results obtained demonstrate that PAHs presence also in raw milk is dependent from environmental pollution but pasteurization and UHT treatments of milk can influence PAHs formation; the differences found between whole and semi-skimmed samples can be due to different fat content of milk.     

Biogenic Amines Content of Four Types of “Pecorino” Cheese Manufactured in Tuscany

Biogenic amines content of four types of Tuscan ewes’ milk “pecorino” cheese was evaluated using HPLC-UV analysis. All cheeses were manufactured in the same dairy factory with different combinations of milk (raw or pasteurized) and type of ripening. Total biogenic amines and tyramine levels of a raw milk “pecorino” ripened five months, partly in a traditional cave, were significantly higher than those of a pasteurized milk “pecorino” with a similar ripening; and of a two months raw milk “pecorino” ripened in the dairy plant. No statistical significant difference was found when comparing total biogenic amines and tyramine contents of the same five month ripened raw milk “pecorino” with a pasteurized milk “pecorino” ripened six months, partly in a traditional “fossa.” In raw milk cave-ripened and “fossa”-ripened cheeses, total biogenic amines exceeded 1000 mg/kg. In cheeses manufactured with raw milk and/or in particular ripening environments, specific hygienic cares are needed to limit biogenic amines formation.     

Evaluation of biogenic amines and microbial counts throughout the ripening of goat cheeses from pasteurized and raw milk

The effect of the hygienic quality of milk on changes in microbial counts and biogenic amine content was evaluated during ripening of goat cheeses manufactured from pasteurized and raw milks at 1, 14, 30, 60 and 90 d. The original milk, rennet, curd and whey were also included in the study. The pH, salt content and extent of proteolysis in the cheese were also evaluated. Spermidine and spermine were the main amines in raw milk, while they were minor amines in cheeses. Other amines increased markedly during ripening, tyramine being the main amine in cheese made from raw milk and cadaverine and putrescine in those produced from pasteurized milk. Enterobacteriaceae counts decreased during ripening whereas those of lactic acid bacteria increased, especially lactobacilli and enterococci. Cheese made from raw milk showed higher microbial counts during ripening than those made from pasteurized milk, especially for Enterobacteriaceae and enterococci, counts being 2 or 3 log units higher. Raw milk cheese showed remarkably higher biogenic amines compared with pasteurized milk cheeses. Therefore, pasteurization of milk causes a decrease in final biogenic amine content of cheese as a result of the reduction of its microbial counts.     

Comparison of the volatile profiles of Arzúa-Ulloa and Tetilla cheeses manufactured from raw and pasteurized milk

Levels of volatile compounds in Arzúa-Ulloa and Tetilla cheeses manufactured from raw and pasteurized milk were investigated. Analysis of volatile compounds in six raw milk (RM) starter-free cheeses (15–45 days old) and six pasteurized milk (PM) cheeses made with deliberately added starters (15–45 days old) manufactured in different dairies, was performed on an automatic dynamic headspace apparatus coupled to a GC/MS. The volatile fraction of RM cheeses displayed 46 volatile compounds (34 for PM cheeses) including fatty acids, esters, aldehydes, alcohols, ketones, hydrocarbons and sulphur compounds. Fatty acids and several esters were only detected in RM cheeses. Moreover, the highest contents of methylketones, secondary alcohols and branched-chain aldehydes and alcohols were also observed in RM cheeses. All results confirm more intense lipolysis in RM cheeses than in PM cheeses. In addition, branched-chain aldehydes and alcohols were significantly more abundant in RM than in PM cheeses, which indicates that catabolism of branched-chain amino acids was significantly higher in RM cheeses. This study has provided useful information which will allow the selection of starter and non-starter bacteria more suitable for manufacturing Arzúa-Ulloa and Tetilla pasteurized milk cheeses with organoleptic characteristics similar to those of traditional raw milk cheeses.