Preparing your students for the Milk Quality and Products CDE January 17, 2015 Howard H. Bonnemann
Milk defect evaluation, milk fat content identification and cheese identification Discuss milk defect identification and cheese identification handout Discuss milk defect sample preparation handout What to look for when evaluating for milk fat content Color, opacity, viscosity, lubricity (greasiness), texture and mouthfeel
California Mastitis Test (CMT) The CMT originated as a modification of the Whiteside test. The Whiteside test was first used in The CMT modification included the addition of bromocresol purple as a pH indicator to aid in visualizing the reaction that occurs. The CMT is based on a reaction of the reagent (a 3 percent solution of alkyl aryl sulfonate) with the nuclear material (DNA) of somatic cells present in milk.
CMT interpretation The greater proportion of Somatic Cells sloughed into the milk through the mammary glands the more DNA material available to react with the reagent and the thicker and more viscous the resultant mixture will become. The CMT is at best a qualitative test, based on the observation skills of the technician
CMT Scoring When the mixture remains completely liquid the SCC is generally below 200,000 and the score would be considered negative. On the score sheet this would be noted as a zero. When the mixture develops a slight graininess that disappears with additional movement of the paddle this would be considered as a trace. This translates to between 150,000 and 500,000 SCC and would be scored a two on the answer card.
Additional CMT Scoring When the mixture develops a distinct precipitate that does not dissipate upon movement of the paddle this would traditionally be given a CMT score of 1. This translates to between 400,000 and 1,500,000 SCC and would be scored as a 4 on the score card. When the mixture develops into a distinct gel but still moves about the paddle this would be considered as a CMT 2 which translates to between 800,000 and 5,000,000 SCC. This would score a 6 on the FFA score card.
CMT Scoring When the mixture develops a strong gel that adheres to the paddle and tends to form a distinct central peak the sample would score a 3 on the CMT and an 8 on the FFA score card. This milk would generally have over 5,000,000 SCC/ml present The color of the reaction can also be utilized in scoring with the lighter bluish white correlating to lower SCC. When a sample turns purple it is indicative of higher pH and very elevated SCC.
Observing the CMT test Ec Ec M94 M94
Individual Written Exam Two parts, 30 questions each, each question worth 2 points – 120 total points possible Written exam now has the most impact on the CDE of any individual event Part 1 is related to quality milk production Part 2 is related to milk marketing
Suggested references for quality milk production National FFA Core Catalog; National Career Development Event Questions and Answers. This document is revised each year, however, the cost is $49. Dairy Foods: Producing the Best, by Dr. Robert Marshall; Instructional Materials Laboratory, University of Missouri – Columbia, y-foods-booklet.pdf y-foods-booklet.pdf
Additional Resources Dairy Foods Curriculum Packet, SDSU Dairy Science Department, Sheri Kahnke and Dr. Robert Baer, A complete revision of this packet is being undertaken during the summer of 2015 to realign more closely with the Milk Quality and Products curriculum Pasteurized Milk Ordinance and Code, Food and Drug Administration SpecificInformation/MilkSafety/NationalConferenceonInter stateMilkShipmentsNCIMSModelDocuments/default.htm or SpecificInformation/MilkSafety/NationalConferenceonInter stateMilkShipmentsNCIMSModelDocuments/UCM pdf SpecificInformation/MilkSafety/NationalConferenceonInter stateMilkShipmentsNCIMSModelDocuments/default.htm
References for Milk Marketing 20is%20Priced.pdf 20is%20Priced.pdf products/dairy.aspx products/dairy.aspx
Additional Milk Marketing references for ordering the most recent copy of Dairy Facts. This publication is listed at $50.