Residues in milk. Dr Bernadette O Brien

Transcription

1 Residues in milk Dr Bernadette O Brien 2017

2 Main Residues Currently Iodine Trichloromethane Chlorates Quaternary ammonium compounds (QACs) DEHP

3 Focus on residues: Two specific products iodine and chlorine associated with 3 residues Iodine used as ingredient in animal feed and as teat disinfectant Chlorine used as disinfectant of milk contact surfaces TCM Chlorate Chlorate: new residue of importance - needs to be reduced significantly New challenges driven by international markets new methods/techniques allow residues to be tested to previously undetected levels Changes in production and processing environments technologies

4 Why is milk iodine a quality issue Ireland major exporter of dairy products Milk quality is critical to maintaining and expanding this market Ireland is one of leading infant formula manufacturers worldwide Market has significant potential for growth Two mechanisms : Milk powder as an ingredient can be sourced abroad Milk powder can be produced and sourced at home-preferable Needs to have correct levels and balance of minerals including iodine Target for iodine in milk powder as an ingredient in IMF : 100 g iodine/ 100g powder equates to <150 g iodine/kg milk Difficult to source at times of year, e.g. - concentrations of >500 µg/kg recorded for December (O Brien et al. 1999, 2013)

5 Iodine sources that can lead to high milk iodine 1. Concentrate feed Early 1990s 139 μg iodine/kg milk; 97% of pasture samples subnormal iodine levels Recommendations for adequate supplementation of iodine mg of iodine /cow per day ~12 mg of iodine /cow per day advised for routine continuous use ~60 mg of iodine /cow per day advised for national use in a 5- month mineral programme for deficient dairy cows 2. Teat disinfection Used as a routine practice on-farm post-milking, and potentially pre-milking Pre-milking disinfection can pose a substantial risk of iodine transfer to milk In Irish scenario same strength pre and post milking Dependent on the degree of removal from the teats prior to cluster attachment

6 International recommendations on iodine requirements for cows 60 mg/cow/day???????????????????????? British Agricultural Research Council - 0.5mg/kg DM intake or approximately mg/cow/day GfE: German Society of Nutrition & Physiology - 0.5mg/kg DM intake or approximately mg/cow/day (1999, 2001, 2004, 2006) US: National Research Council 0.6mg/kg DM intake or approximately mg/cow/day (1989); reduced to 0.5mg/kg DM intake or approximately mg/cow/day in 1994, 1998, 2001)

7 IODINE Average monthly Iodine concentrations for 8 processor milks-2013 Iodine concentrations for 8 individual processor milks at 13 dates Av = 143ppb; range ppb

8 Target: iodine level in powder = 100µg/kg Target: iodine level in milk = <150µg/kg Iodine quantification on 65 farms in one processor area Average value of farms = 164 µg/kg milk Average value of all tankers = 130 µg/kg milk Value of whole milk silo = 136 µg/kg milk Value of skim milk silo = 142 µg/kg milk Av value good Predict level No contribution from processing When there is an Iodine problem 4 farms >250 µg/kg milk Average value of 4 farms = 389 µg/kg milk (±142) Farm 1 = 449 µg/kg kg meal/c/d - 70 mg - no I teat disinfection Farm 2 = 561 µg/kg kg meal/c/d mg + I teat disinfection (post) Farm 3 = 289 µg/kg kg meal/c/d - 30 mg + I teat disinfection (post) Farm 4 = 257 µg/kg kg meal/c/d - 10 mg - no I teat disinfection Feed sig factor Iodine disinfection

9 High iodine intake risks Cows fed high concentrate feed levels with high levels of iodine added Iodine routinely added to feed rations at 5-30 mg/kg Cows typically fed 3 kg/cow/day in early lactation or higher can potentially receive mg/cow/day Level of iodine in feed set a/c to the volume fed but when actual feed levels > planned feed levels then excessive iodine intakes Cows require 0.5mg/kg DM/day = 10 mg iodine/day 2 kg meal with 3 mg/kg iodine Cow intake at grass is 18kg DM/day = 6.0 mg iodine contributed by meal = 4.5 mg iodine contributed by grass

10 Previous research: Two main pathways to high milk iodine high iodine levels in meal and changing feed levels teat disinfection with iodine (not removing before cluster attachment), Bolus Minerals added to drinking water Current work indicating high iodine levels in meal Excess iodine ingested through feed is excreted in milk and urine Feed industry responding and reducing iodine levels added during feed manufacture

11 Conclusions Recommended supplementation level a/c to animal research documentation is 0.5 mg/kg DM/cow/day or ~10 12 mg/kg/cow/day Supplementation levels up to 60 mg/cow/day (up to 6 x) Seasonal problem in Ireland; early lactation & winter Milk iodine level is most important in areas where milk is destined for IMF At a limit of 150 μg/kg little flexibility Supplement more precisely to meet requirement Contribution of Bolus, Minerals added to water, Mineral licks, Drenches to be taken into consideration

12 TCM development (Trichloromethane) TCM is a by-product of the disinfection process when chlorine is used Chlorine very hygienically effective, cost effective and efficient disinfectant BUT if milk is not rinsed from equipment before the detergentsterilizer is used Chlorine binds to the milk - total organic chlorine Clear, colourless and volatile Accumulates in fat portion of milk and fat rich product Target level in butter = 0.03 mg/kg or less» Target level in milk = mg/kg Need to meet this to maintain good markets Lactic Butter

13 Main causes of high TCM Cleaning products having too high chlorine levels Improper usage of products containing chlorine Insufficient rinsing of milking equipment after the wash cycle Measures: 1.Products? 2.Developed test 3.Identified source 4.Checklist and recommendations 1. Products? - Created a list of chlorine containing cleaning products Product 1 Product 2 Product 3 Product 4

14 2. Developed a test for TCM Analysis GC 25-27,000 samples tested per year

15 3. Identified source of the problem Farms Tankers Assembly Processor Identified tankers high in TCM Ensured correct cleaning products and training of personnel Identified high TCM farms within high TCM tankers Concentrated within 6 processors easier to CONTROL inside factory Removed chlorine Investigation of farm issues and troubleshooting by MQ personnel

16 Critical control points to maintain low TCM levels in milk Rinse volume of water after milking Rinse volume of water after detergentsterilizer wash cycle Chlorine content of detergent-sterilizer Volume of detergent-sterilizer used Addition of chlorine to rinse water Recycling of detergent-sterilizer solution Cluster dipping in chlorine Recycling of rinse water

17 Moorepark project 4-pronged approach TCM analysis Set up of Methodology Current annual sample throughput = 25,000 30,000 samples Correction of TCM problems on-farm Farm visits together with report and advice on solving problem Continuous communication of results and information with milk quality personnel and Research - Controlled experiments on reducing TCM in milk while maintaining good microbiological quality Laboratory based studies Moorepark milking parlour based studies Farm based studies Chemical analysis of detergent-sterilizer products Web page set up to inform industry on different detergent products based on chemical analysis

18 Chlorates TCM Detergents containing Chlorine Chlorate

19 Chlorate development Chlorate is a by-product formed during de-compositional changes during storage of e.g. Na hypochorite Commercial solutions of Na hypochorite usually contain 8 14% chlorine Different to TCM formation no other ingredient involved Currently, there is no known treatment available to remove chlorate once it has been formed in water Influencing factors are: Chlorine level Storage conditions Storage duration Typical Specification as set by IMF companies 50 ppb in skim milk powder; 50 ppb in whey powders; <20 ppb in lactose No MRL set yet in progress Default MRL in milk = 0.01 mg/kg = 10 ppb, e.g. concentration effect

20 1. Identify source of the problem Cleaning product containing chlorine Cleaning product containing chlorine Treated water Farms Assembly Processor Results of 67 farms 8 had Chlorates >0.001 mg/kg Need to focus on processing easier to CONTROL inside factory

21 2. Development of test New MS methodology now commissioned at Teagasc Ashtown Accreditation completed Methodology for chlorate analysis in milk detection limit 2 ppb It is expected ~180 test samples per day or ~900 per week Also be possible to analyse water samples using this technology

22 At farm and processing plant On farm Ensure careful use of products which contain chlorine, use same precautions as for TCM control (products and rinsing) In addition: Minimize storage duration - purchase product frequently Avoid stock piling products Store product under cool dark conditions In plant Focus on rinsing protocols to ensure sufficient rinsing to remove all residues from plant surface after cleaning System for regular purchase of cleaning products Consideration to removal of hypochlorite as a cleaning agent non-chlorine cleaning options available Ensure the optimum quality of water for rinsing

23 Quaternary Ammonium Compounds Industrial biocides - minimize bacterial growth and biofilms Commonly used in hand cleaning products also present in teat sanitizing wipes; Steri7 EU member states required to carry out investigations Test developed at Teagasc

24 Dairy farms milk liners, tubing, etc

25 Regulation - DEHP not to be used in liners in EU since February, 2015 Look at effect of regulation in migration tests?

26 Thank you