Water Activity News 2002

2002 Trade Shows Institute of Food Technologists Food Safety February 20–22 Atlanta, GA Food Safety Summit March 13–15 Washington, DC

Water Activity for Food Quality Everyone knows the importance of water activity in food safety. Read on for “the rest of the story.”

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O MUCH GOES INTO MAKING THE PERFECT FOOD — cooking to the palate of Joe and Jane Public is an art. An acquaintance of ours is a cookie artist. He has found the perfect cookie recipe: soft, moist, and chewy. Unfortunately, now Pet Food Forum April 6–10 he has mold problems. “I spent a bundle on a moisture balance to Chicago, IL measure moisture content, but it hasn’t solved the problem,” he confided. “How can I get a handle on this?

In this issue of Institute of Food Am I measuring the wrong thing?”

Water Activity Technologists June 15–16 News He’s on the right track—water is the Anaheim, CA problem. But just getting a “water number” n Water activity won’t help. He needs a number that International measurement and accurately and consistently predicts Association for water content continued on next page Food Protection usage- pros XXXXXXXXXXXXXXXXXXXXXX June 30–July3 and cons.

San Diego, CA IFT Pre-meeting Workshop “Fundamentals of Water n IFT aw Workshop National Environmental Activity” Review Health Association ECAGON CONTINUES TO place a high June 30–July 3 value on water activity education. We n Shelf-stable Minneapolis, MN understand that the more you know about sandwiches water activity and all of its applications for product quality, safety and shelf life, the n Seminar update happier you will be with our instruments.

Therefore, we have been offering one-day n New standards seminars around the country to present this packaging basic education. Last year we approached the IFT Continuing n Examples of Education Program about giving our moisture Z seminar as part of their pre-meeting measurement program. They agreed, so, we worked to put together a program that would fit their requirements, Check out Decagon’s new calibration and the result was much better than we even imagined.

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standards for AquaLab water activity meter. Story on page 6.

Shown above at actual size.

IFT wanted someone from academia to sponsor the program. We contacted Dr. Gustavo Barbosa-Canovas, an continued on page 3

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Food safety building blocks continued from front cover product quality. The five senses are excellent detectors of quality. A customer biting into a cookie knows immediately if it’s moldy or stale, just as a fan walking into the Astrodome knows if it’s chilly inside. But as a facilities manager, I would like to accurately predict how the fan will feel before he enters the building. Knowing the heat content of the Astrodome is useless to me. I need to know the temperature. In the same way, you want to predict product quality before your customer ever takes a bite. Water content is practically useless to you. You need to know the water activity.

Water activity describes quality because it describes more than how much water is in the product. It describes how much water is available, ready to be used. And knowing that number gives you information that you otherwise wouldn’t have, letting you predict what your customer will taste without ever having to taste yourself.

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Our friend the cookie artist needs to know absolutely whether or not his product will mold on the shelves. But he also wants to keep the cookies moist and chewy. The cookies will be the right consistency within a certain range of water activities. And within another range, he is confident of avoiding mold. Put the ranges side by side, and he’ll find his “water activity sweet spot,” a small range of values that describe the perfect cookie. If you hit the sweet spot, you get the perfect cookie. Every time.

After finding his sweet spot, he adjusts his cookie recipe. Then he Stop wasting time measures water activity fiddling with the of the finished product, wrong instrument.

Get the AquaLab even doing spot checks water activity on the line. As long as meter and he stays within that watch your value, he can ship to product go. market with confidence. His moisture balance,

Water content vs water activity. Let’s take the gloves off and compare.

accurate as it is in finding water content, can’t make that prediction of quality.

Moisture content tells how much water, and nothing more. It is almost useless as a measure of total food quality.

When it comes to food safety and quality, knowing the water activity is powerful. To food dehydrators, avoiding spoilage is the key. They know they need dry, but how dry? Water content measurements are a sloppy way of measuring “dry enough.” They lead many dehydrators to over-dry their product. There is a specific water activity number below which food will not spoil. By measuring water activity, dehydrators get the product exactly dry enough, without getting it too dry. It’s still a safe product, but now it also has lower production and ingredient costs.

Combine crackers at 20% water content and cheese filling at 30%. A recipe for soggy crackers? Not if the two ingredients have the same water activity. Need to avoid clumping and caking in a batch of spices? Match the water activities of the components and the problem is solved. Vitamin degradation is a function of water activity. So are lipid oxidation, crunchiness, chewiness, softness, and many other factors of quality. A measurement of water content will tell you how much water is in a product, but that’s all. It can’t answer any of these other quality and safety issues.

So why do so many people still measure water content? For most, it’s because it’s what they’ve always done. Some have contracts with suppliers or buyers that specify a certain moisture content.

But measuring water content only makes sense if “How much water?” is the only question that needs an answer. If product quality and safety are the issue, water content is almost meaningless. People only keep measuring it because they don’t know a more powerful measurement is out there, one that answers the real questions quickly and accurately.

If you have quality or safety issues, call the food scientists at Decagon for a free consultation. You may find that measuring water activity is a powerful solution.

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Are you thinking of switching from measuring water content to measuring water activity?

continued from front cover IFT Pre-meeting Workshop

æ Dr. Larry Beuchat, Distinguished Research Professor, Center for Food Safety at the University of Georgia, showing the effect of water activity on preventing microbial deterioration. æ Dr. Leonard Bell, Associate Professor of Food Physical Chemistry at Auburn University, giving information on water activity and reaction rates, physical properties, and shelf life.

Associate Professor of Food Engineering of the Department of Biological Systems Engineering at Washington State University, and he agreed to assist. Dr. Anthony Fontana, Jr., Senior Research Scientist at Decagon. Together they were able to æ Dr. Henry Leung, Research Consultant at Frito Lay, wrapping up the program with industrial organize an impressive program featuring a applications. “who’s who” list of water activity experts.

Scheduled speakers include: æ Instrument demonstrations by different water activity manufacturers æ Dr. David Reid, Professor of Food Science & Technology at the University of California-Davis, introducing the water activity concept.

We have been asked about the difference between this workshop and our single-day seminar of the same title. Our single-day course æ Dr. Theodore Labuza, a Morse Alumni Distinguished Teaching Professor of Food Science is a basic course meant for people with little background in water activity. It’s taught by Dr. at the University of Minnesota, discussing Fontana and other Decagon personnel. The IFT moisture in foods, including the relationship workshop is more advanced seminar by several between moisture content and water activity. leading scientists who are experts in water activity and moisture research of food and æ Dr. Shelly Schmidt, Professor of Food pharmaceutical products.

Chemistry at the University of Illinois, detailing water mobility in foods and how it relates to quality and shelf life. æ Dr. Yrjö Roos, Professor of Food Technology at the University College Cork, Ireland, introducing glass transition and its relation to water activity. æ Dr. Gustavo Barbosa-Canovas (see above), sharing models for water activity prediction in real food systems and also water activity in reference to dehydration/drying.

Need a stamp of approval?

AquaLab water activity meter uses the AOAC approved method for measuring aw.

æ Dr. Anthony Fontana (see above), presenting water activity measurement methods.

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SOURCES: 1. ABCNEWS.com- New Secret Weapon 2. http://www.natick.army.mil:80/warrior/02/marapr/pockets.htm 3. US military creates indestructible sandwich http://www.newscientist.com/news/news.jsp?id=ns99992151

Indestructib

Shelf-stable sandwiches approved for Meal, Ready-to-Eat Pepperoni stick and barbecue chicken pocket sandwiches have been approved for the Meal, Ready-to-Eat (MRE).

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HE SHELF - STABLE SANDWICHES

were first developed by the Department of Defense Combat Feeding Program at the U.S. Army Soldier Systems Center (Natick) in the mid1990s as a ration to enhance soldier mobility.

They require no refrigeration or freezing, utensils or heat source before consuming, although they can be warmed with a flameless ration heater.

“What this gives us is something unique,” said Dan Nattress, project officer. “We’ve combined shelf-stable bread that now supplements the MRE with meat into a lightweight, identifiable, eatout-of-hand food.”

Shelf-stable sandwiches are comparable to Hot Pocket™ sandwiches found at the grocery store in size, calories and appearance, but the major difference is in the processing that allows the food to meet the Combat Feeding Program’s minimum shelf life requirements of 3 years at 80°F or six months at 100°F. Military rations are commonly stabilized through thermal processing in retort pouches, but heat tends to destroy the flavor and texture of the sandwiches, said Michelle Richardson, also a project officer.

Instead, the sandwiches are developed using intermediate moisture technology. Products using this technology are preserved by controlling water activity and acidity levels. Humectants, which are

substances that promote water retention, help lower water activity by reducing the amount of water available for bacteria growth. The pH or acid levels are controlled by choosing low-acid ingredients or incorporating natural acids into the product.

The amount of oxygen in contact with the food is also controlled by including oxygen scavenger packets. The sandwiches are packaged in trilaminate pouches to prevent the transmission of water and oxygen, both necessary for the growth of yeast, molds, and bacteria.

“The combination of meat with the bread with differing water activities and pHs makes both safety and acceptability a concern,” Richardson said. “The water activity of the different components needs to complement each other.

If the water activity of the meat is too high, you may get soggy bread.”

Water activity measurements for this shelfstable project were performed with Decagon’s AquaLab water activity meter.

She said the shelfstable sandwiches were acceptable to soldiers who tried them, and they meet Food and Drug Administration requirements for food safety.

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ble Sandwich The sandwiches are being further developed and commercialized under a Cooperative Research and Development Agreement with GoodMark Foods, Inc. in Raleigh, N.C. By partnering with industry, production costs should decrease while opening the opportunity for sales in areas such as vending machines for anyone who wants a lightweight, nourishing meal that requires no preparation or silverware, said Nattress.

Other varieties under consideration are a pizza pocket with Italian sausage and pepperoni slices in a tomato sauce, sliced beef in a barbecue sauce, tuna or chicken salad, ham and cheese, and peanut butter and jelly.

“Just about any variety you can make with a Hot Pocket you can make with this,” Nattress said. The same technology is being applied to a new program in combat breakfast foods.

“The number of breakfast items available to the warfighter is very limited and not highly acceptable,” Richardson said, who’s leading the research. “The investigation of inter-component films and coatings may allow the use of ingredients previously impossible due to moisture or fat migration.”

Some concepts that Richardson has proposed are cream cheese-filled bagels with and without fruit fillings, sausage and cheese biscuits, breakfast burritos with bacon and eggs in a tortilla wrap, and breakfast pizza. Prototypes are scheduled to be ready this year with production planned for 2004.

An Update on the

“Fundamentals of Water Activity” Seminar

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“Fundamentals of Water Activity” one-day seminar to over 100 people. At the end of every seminar we ask those in attendance to give us feedback on the seminar. Two things really stand out: 1) We have improved in every category we asked about from 2001 to 2002, and 2) Over 90% of those who attended would recommend the course to others.

E HAVE NOW PRESENTED OUR

Our goal in providing water activity education is to help our customers (and even some of our competitor’s customers) get maximum value from their water activity instrumentation. Apparently we are reaching our target. One attendee wrote, 'Who would have known that aw is involved in so many things!" Other course participants were surprised (and glad) that it was not a sales pitch.

Our Fall 2002 and 2003 Seminar schedule has yet to be finalized. We would appreciate your feedback to help us determine the future dates and locations of our upcoming seminars. Please visit www.decagon.com/seminar to leave us your feedback so that we can best serve your needs.

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We Heard You! Introducing New Standards Packaging

Time to use water activity for your product shelf-life predictions.

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ECAGON ’ S MISSION INCLUDES

attention to customer service. When you said you needed plastic instead of glass vials, we started investigating that possibility. We found that not only could we package the standards in plastic vials, we could respond to other customer feedback as well. Some wanted to buy fewer vials at a time, so the vials are now packaged in 50-vial boxes which can be purchased individually. Some customers wanted a different variety of standards than offered in our “variety” case. Now that the standards are available in boxes, you can purchase any combination of standards without paying a premium for a special combination. We also thought you might like the vials in a handy dispenser box. Since all of our customers like saving money, we are passing the cost savings of the new packaging on to you. Even when purchasing one box at a time, you save 37cents per vial. If you purchase more than one box at a time you get 100 vials for the old 72 vial case price of $135, and save 52 cents per vial.

New Verification Standard Packaging at a glance.

1 New plastic vials.

2 New handy dispenser box.

3 Now in 50 count boxes.

4 Single box for only $75.

Multiple boxes for $67.50 each.

5 Buy any combination of w levels.

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6 More vials for the same price.

Thermal Conductivity and Thermal Diffusivity KD2 is designed for for Foods use in solids, gels, powders and now liquid samples.

KD2 for foods.

New AquaLab performance standards. (actual size)

•Direct readout •Portable •Compact •Easy to use

Call today.

DECAGON

800-755-2751 509-332-5158 kd2@decagon.com www.decagon.com/kd2

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When to use water activity versus water content: 3 examples of moisture measurement.

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“which is the best moisture measurement?” comes with an understanding of the processes.

HE RIGHT ANSWER TO THE QUESTION

A simple example where water content is clearly the measurement of choice is when one wishes to buy or sell a product on a dry weight or standard moisture basis. The water content of the sample must be measured to compute the amount of water and dry matter present.

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CORN MUSTARD

Water Content (%)

25 20 15

product. This is because it is the water activity, not the water content that determines whether these organisms can carry on their physiological functions. When the water activity is below 0.6, water is so tightly bound by the product that it becomes unavailable to even the most xerophytic fungi.

Water content is irrelevant in this application because the microbes respond to the availability, not the amount of water. Thus, even though it is common practice to measure water content for this application, water activity is a much better measure. Water activity is not product specific, and is fundamentally related to the process we are interested in.

Another example where water content is almost useless is in predicting moisture migration in multicomponent products.

10 5 0 0

0.2

0.4 0.6 Water Activity

0.8

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Figure 1.

Isotherms for corn and mustard.

Now consider a situation where the measurement of moisture is used to determine whether a product is shelf stable, will store safely without spoilage, or will support microbial production of toxins.

The three vertical lines in Fig. 1, at water activities of 0.60, 0.85, and 0.94 represent limits below which, respectively, no spoilage occurs, products are defined as shelf stable, and toxin production by botulism is stopped.

From the figure it is clear that corn can be stored without spoilage if its water content is below 12.5%, and mustard is similarly safe if its water content is below 7.5%. In fact, these are values that have been used for years to determine whether these products are safe to store.

But the water content below which spoilage fungi are inhibited is different for each different

Moisture moves from regions of high energy to regions of lower energy. Water content has nothing to do with the direction of flow. Flow is completely determined by gradients, or differences in water activity.

If we were to mix mustard at 15% moisture with corn at 20% moisture, which way would the water move? Referring to Figure 1 we see that the water activity of corn at 20% moisture is 0.91. The water activity of mustard at 15% moisture is 0.93. The moisture would therefore move from the mustard to the corn, even though the corn has a Don’t let your profits fly away because substantially higher you’re not measuring water content. water activity.

This problem is best solved using water activity measurement because the fundamental processes are controlled by energy, not by amount of water.

In general, water activity is the right measurement when microbial processes, including food spoilage, are of concern. Also, moisture migration, physical properties and caking are best addressed using water activity measurements.

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New and upcoming chapters on water activity and its measurement.

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Dear Customers, Food safety is once again in the news. Our local newspaper picked up an AP story “Dangerous food bacteria here to stay”. In the story, unnamed scientists presented a report to the Institute of Food Technologists. The story referred to the importance of water activity control (without mentioning it by name) to limit the growth of dangerous bacteria.

Also, we were present in March when the new director of Homeland Security, Governor Tom Ridge, addressed the attendees of the Food Safety Summit in Washington DC. His message was that it would take all of us working together to ensure food safety.

At Decagon, we work to give you the highest accuracy water activity measurement possible so that when food safety is critical, you have a measurement you can trust.

Sincerely,

ECAGON , IN ITS CONTINUING

effort to be the leading experts in water activity technology, is involved in several book projects on water activity and its determination.

Already in print is a chapter in the “Current Protocols In Food Analytical Chemistry” published by John Wiley & Sons, Inc. Fontana, A. J. (2001). Dew-Point Method for the Determination of Water Activity. In: Current Protocols In Food Analytical Chemistry.

Wrolstad, R.E. ed., John Wiley & Sons, Inc., New York p.A2.2.1-A2.2.10.

Scientists at Decagon are also working on “Water Activity” chapters in two other upcoming publications. The first is a chapter in the “Handbook of Food Analysis: Second Edition” edited by Professor Leo M.L. Nollet and published by Marcel Dekker. The second is an entire book devoted to the topic of water activity. This book is to be published by Iowa State Press, a Blackwell Science company and edited by; Dr. Gustavo Barbosa Canovas of Washington State University, Dr. Shelly Schmidt of University of Illinois, Urbana, and Dr. Anthony J. Fontana at Decagon Devices.

Tamsin Campbell Product Manager

APPROVED METHOD

Decagon Devices, Inc. publishes Water Activity News annually.

No subscription or dues.

ISSN# 1083-3943.

Printed in USA. ©2002 DECAGON

DECAGON 950 NE Nelson Court Pullman, Washington 99163

800-755-2751 fax 509/332-5158 aqualab@decagon.com www.decagon.com/aqualab

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