Virginia Polytechnic Institute and State University

Susan Duncan, Dairy and Sensory Evaluation

Bill Eigel,                Food Biochemistry

Joe Marcy:               Food Processing

Merle Pierson: Food Microbiology

 Sean O’Keefe: Food Chemistry

Susan Sumner:   Food Safety

Walter Hartman:    Dairy Plant Manager whartman@vt.edu

Kim Waterman:  Dairy Chemistry    Kwater@vt.edu

     updates at virginia tech

Food Science Student Wins NFPA Award

The National Food Processors Association (NFPA) named Janet Webster, a Ph.D. student in Food Science and Technology at VA Tech, the recipient of the 2004 NFPA Graduate Student Award. As part of her Ph.D. research, Janet will focus on light oxidation of milk and nutraceutical beverages. The specific focus of her work is the development of packaging materials that inhibit light oxidation in milk and nutraceutical beverages. She will also work on the development of a novel technique for monitoring light oxidation and determining the specific chemical reactions that are initiated in these products when they are exposed to light.

This award recognizes an outstanding student in the area of food technology or food science who has demonstrated the ability to enhance the safety, nutrition and wholesomeness of food products through research and scholastic achievement in one or more food science disciplines. The award provides a scholarship to be used for the continuation of the student's education in food science or food technology.

“Clearly, this is scientific research of significant value to the food and food packaging industries, which is why the selection panel focused on Ms. Webster to receive this Award,” stated Susan Ferenc, DVM, Ph.D., and NFPA's Executive Vice President of Scientific and Regulatory Affairs and Chief Science Officer.

HOT TOPICS AND DAIRY ISSUES

Schools Replacing Milk Cartons with Bottles

A recent milk industry study determined that children drink more dairy when it comes in round plastic bottles, and as a result, a growing number of schools are retiring the old paper half-pint cartons.

Already more than 1,250 schools have switched to single-serving bottles. While that is still a tiny fraction of the nation's schools, it has jumped from 2000, when there were none.

Paper containers are hard for kids to open, and often teachers spend the whole lunch period opening containers. Educators say plastic caps are easier for children to open and the round bottles fit better in their hands. Plastic has been favored as packaging for soda and other drinks for a long time, but schools became interested in bottled milk only after a 2002 Dairy Council study found that milk consumption increased 18% in schools that tested bottles. The study also found that children who drank bottled milk finished more of it.

Many schools display the bottles in glass-front upright coolers – just like at the convenience store – and obesity concerns have prompted schools around the nation to oust soda machines in favor of milk vending machines. Even though bottled milk costs schools more, high schools that served it during the study saw lunch program participation increase nearly 5%.

In 2001, more than 82% of the nation's milk was packaged in plastic, up from 15% in 1971. The milk industry hopes to instill a trend among children that will result in a lifetime of increased milk consumption, reversing the declining milk intake that has been occurring since the 1970's.

New Pasteurization Testing Regulations

In October 2004, more demanding pasteurization testing regulations went into effect for U.S. dairies, and these regulations will probably soon be adopted in Europe. The new requirements came about as a result of growing consumer and government awareness of food safety and quality issues. Traditional pasteurization tests may no longer be acceptable and dairy labs must adopt new testing procedures that meet the more stringent regulations and provide a higher level of quality control.

Testing for proper pasteurization dates back to the 1930's when it was discovered that the enzyme Alkaline Phosphatase (ALP) was inactive at slightly higher time/temperature conditions (71.7°C for 15 sec) than those required to kill Mycobacterium tuberculosis. This heat treatment also killed most other milk-born pathogens. The ALP test measured the amount of ALP that was not denatured by pasteurization. Two forms of the test were standardized internationally to provide approved methods to validate pasteurization. In the U.S. , the Scharer Test was based on the liberation and measurement of phenol. In the U.K. and Europe , the Aschaffenberg & Mullen test measured the release of nitrophenol. Both methods used visual color measurement to determine ALP levels. The lowest level of sensitivity for these methods is about 0.1% raw milk and the legislated limit for ALP was set at this level. Therefore, cow's milk could pass the statutory test and still contain 0.1% raw milk.

After 60 years, it became apparent that the capabilities of ALP colorimetric testing were no longer adequate to meet rising consumer food safety concerns. In the 1990's, new pasteurization testing procedures with much higher levels of ALP sensitivity were developed. After a comprehensive review, the FDA lowered the ALP acceptance criteria from 500 mU (4 µg) of phenol/ liter (0.1% raw milk) to 350 mU (3 µg) of phenol/liter (0.075% raw milk). These regulations went into effect in October 2004 and Scharer colorimetric testing is no longer accepted. Although ALP acceptance level remains 500 mU/liter in Europe , the EU dairy product safety committee has recommended that the statutory limit be lowered to 350 mU/liter. The EU has stated its intention to adopt these recommendations, and codification is expected in the coming months.

Fluorophos ® ALP and chemiluminescence are new pasteurization testing options that meet the new ALP limit. Each has strengths that may influence suitability for various dairy labs. The Fluorophos ® ALP test is based on the same chemistry used in colorimetric tests, but involves the liberation of a chemical measured by fluorescence rather than color. This test was developed by Advanced Instruments, Inc. and it uses an automated fluorometer and a fluorometric assay. It is sensitive (measures down to 0.003% raw milk), quick (3 min) and the instrument interprets the results instead of a technician. The test has been approved by the International Standards Organization, International Dairy Federation, Interstate Milk Shippers and AOAC. It can be used to confirm pasteurization of many different dairy products including bovine, sheep, and goat milk, flavored and cultured products, and cheeses.

Chemiluminescence, developed by Charm Sciences, Inc., employs a substrate reagent that produces a light intensity directly proportional to the amount of phosphatase enzyme in the sample. The light is scanned by an automated luminometer that interprets the results. This test is also sensitive (0.005% raw milk) and quick (4 min). No sample preparation is needed with fluid white milk; however, a 5 min preparation step is necessary for non-flavored, flavored, and solid/semi-solid dairy products (cream, chocolate milk, cheese and yogurt). This test has been approved by the Interstate Milk Shippers.