Water Activity News 2003

SPECIAL ISSUE

20 th

2003

Celebrating our 20th Anniversary as an IFT Exhibitor: A trip down memory lane

by Tamsin Campbell

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TWENTY YEARS AGO, the business path for Decagon Devices, Inc. changed. We were a two person company working out of a spare bedroom. Our main (and only) product at the time was the SC-10 psychrometer for measuring soil water potential.

Somehow, Dr. Henry Leung heard about this instrument and asked Dr. Gaylon Campbell and me to come and demonstrate the instrument on food. He told us that the soil water potential measurement was easily converted to what the food scientists called “water activity”. He said that all the currently available models were expensive and slow and he was looking for an alternative. He guessed that his colleagues would be interested too.

Armed with that information, Joe Harris—the first continued on page 2 Z

Fast Water Activity Measurements

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quaLab since its introduction has set the standard for speed and accuracy in water activity measurement. This summer, at IFT, Decagon will unveil a new instrument that continues this tradition. AquaLab Quantum measures water activity almost instantaneously. This instrument utilizes NIR spectroscopy to determine the activity of the water in the sample, NOT the water activity of the vapor in the headspace as traditionally done.

NIR technology is widely used to measure water content and other chemical components of materials. Using a moisture sorption isotherm relating water content and water activity, these NIRmeasured water content values can be used to infer water activity. AquaLab Quantum’s approach is different. Water activity is a measure of the energy status of the water in a product. As water is “bound” in a product, its chemical potential energy is lowered. Reducing the energy status of the water continued on page 3 Z

ANNIVERSARY

PITTCON Orlando, FL March 9–14 Food Safety Summit Washington, D.C. March 18–20 Petfood Forum Chicago, IL March 31–April 2 Decagon Seminars New Jersey, Chicago, LA, Minneapolis, Atlanta

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2003 trade shows and conferences

National Environmental Health Association Reno, NV June 6–11 Institute of Food Technologists Chicago, IL July 13–16 International Association for Food Protection New Orleans, LA August 10–13

IN THIS ISSUE n 6 Celebrating 20 years at IFT 6 Tradeshows & meetings 6 New service contract 6 Fast a w measurement 6 Pawkit: Snack meats 6 a w and pet foods 6 On-line downloads

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20th Anniversary: down memory lane (continued from front)

president of Decagon—joined Dr. Campbell on a 2500 mile drive to our first IFT exhibit in New Orleans.

Each man took their turn driving in 100 mile increments.

We demonstrated the SC-10 at this expo. Mr. Harris recalls good interest in the new instrument at the show.

However, water activity was still a fairly new concept.

At the exhibition we met Dr. Ted Labuza, a recognized authority on water activity theory and measurement, for the first time. Over the years, his feedback and critique of our instruments has been invaluable.

A big drawback to the SC-10 was its small sample size (though it could equilibrate 10 samples SC10 water potential meter 1983 at a time.) Each sample cup could only hold 1.5ml. By the 1984 IFT Expo we introduced the SC-3 with 3 samples of 7ml each. This instrument incorporated the same thermocouple psychrometer measurement method as the SC-10. The sensor for this instrument was two tiny wires, one of chromel, and the other of constantan. These wires were welded together and the junction was coated in ceramic. To measure aw, the ceramic tip was dipped in water and placed above the sample. This water evaporated into the air above the sample and the resulting change in SC3 water activity voltage at the junction was meter used to calculate water activity. As it turned out, this sensor was too delicate for regular and frequent use. However, the market interest was obvious so we began work on a new design.

Sometime in 1986, our newly hired engineer, Chen Xing (did you ever wonder where the “CX” came from?) began work on a new type of sensor. Decagon’s chilled mirror dewpoint sensor, a key feature in all future AquaLabs, was born. The chilled mirror dewpoint sensor measures water activity by chilling the mirror until condensation forms. The temperature at which that occurs is the dewpoint temperature, and CX1 water activity meter 1987 is directly related to water activity with no calibration. Our first instrument to use this measurement method was the CX-1. For the initial 2

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First thermocouple psychrometer with removable cups.

Manufactured by Dr. G.S. Campbell , 1978

CX-1 design we also relied heavily on assistance from Campbell Scientific, Inc, one of Decagon’s owners. We introduced it at the 1987 IFT. The early design of this sensor, while performing the measurement with high accuracy and speed, proved to be somewhat delicate. We AquaLab CX2 1989 redesigned and introduced the CX-2 model by the 1989 IFT show.

In 1990, we added temperature control with the option to circulate water through the instrument, calling it AquaLab Series 3TE the CX-2T. Sometime in the early ‘90’s 1998 we adopted the name “AquaLab”. In 1998 we introduced our latest model of AquaLab, the Series 3 with the Series 3TE following shortly thereafter.

These models incorporate many “user-friendly” and operational features to improve the instrument. The Series 3TE, replacing the CX-2T, incorporates an internal Peltier device for temperature control, and eliminates the need for an external water bath.

Pawkit, the world’s first truly portable water activity meter, was introduced in 2000. At four inches long and weighing four ounces, this meter is the smallest water activity Pawkit meter available. It is battery-operated and portable 2000 is meant for quick check during production or for people who need water activity measurements when they need to travel.

As we celebrate our 20th anniversary, Decagon’s water activity technology continues to help food scientists and QC managers produce safer, higher quality, and more nutritious products around the world. Decagon is introducing two new instruments to further aid food companies at this years IFT Food Expo. First is an Instantaneous Water Activity Meter, which will vastly reduce the time for product analysis and allow on-line analysis of products. Second is a Safe Storage Monitor that allows long term in situ monitoring of water activity and temperature. The Safe Storage Monitor will log up to five water activity probes for in-package, in-silo, in-container, or any other remote water activity monitoring needs. It also is available with a radio telemetry option. We look forward to exhibiting at IFT for many years to come as we continue to lead the world in water activity technology.

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Can water activity measurements be fast? (continued from front)

also affects its spectral properties. By monitoring changes in the spectrum of reflected light, AquaLab Quantum determines the water activity of a product.

Currently, water activity measurement requires placing a sample into a sealed chamber, allowing the water in the sample to equilibrate with the water vapor in the headspace, and then measuring the humidity of the headspace. While this allows accurate water activity measurements, the process of the air above the sample equilibrating with the water activity of the sample itself takes time. The diffusion of water from the sample to the vapor phase is controlled by the properties of the sample and equilibration times vary with sample matrix. Furthermore, measurement time is sometimes lengthened by the time required for the sensor to equilibrate with the headspace. Add to this the fact that most systems require time to reach thermal equilibrium, which is necessary for accurate measurement in most water activity instruments.

Equilibration is an extremely time-consuming process.

With technology improvements, the time required for vapor equilibrium has consistently decreased. A report in the soils literature about 50 years ago, describing a thermocouple psychrometer system used for measuring water activity, suggested an equilibrium time of a week. Early mechanical hygrometers required a day or more for water activity measurements on foods. Decagon’s SC10A thermocouple psychrometer used for foods measurements about 20 years ago required 20 minutes for thermal equilibrium and 1 to 2 minutes measurement time per sample. It read 9 samples at a time. With improvements in materials and sensors, the AquaLab dewpoint instrument now reads individual samples in 2 to 5 minutes.

While speed improvements over the past 50 years are impressive, the physics of the diffusion process places a lower limit on the time required for a The fastest water activity measurement system.

measurement. To further decrease the measurement time, a new approach is needed which measures the water directly in the sample and not in the headspace. AquaLab Quantum overcomes these hurdles to fast measurement times by measuring the water activity in a sample using light, eliminating the need for equilibration with a vapor phase.

AquaLab Quantum

AquaLab Quantum measures water activity by shining a bright light on the sample itself and collecting the reflected spectrum of light. When light is reflected from a sample, the reflected light is characteristic of the composition of that sample. In other words, a sample with a water activity of 0.300 will reflect light differently than a sample with a water activity of 0.320. AquaLab Quantum measures this reflected light and converts it to water activity values using specialized software. Since there is no measurement of the air above the sample, no equilibration time is needed. In addition, because the method of detection travels at the speed of light along a fiber-optic cable, the time for a water activity measurement is almost instantaneous.

Since the fundamental relationship between spectral information and water activity is not fully understood, AquaLab Quantum requires a product specific calibration. For a particular product, samples of varying water activities are prepared.

The instrument scans and saves the reflected spectra of these samples. The user then inputs the actual water activities (obtained from measurement in an AquaLab) of these samples into specialized spectral processing software, which associates the water activities with the saved spectra. Using the water activities paired with their corresponding spectra, a calibration curve is produced. This calibration is now used to determine the water activity of the product with the touch of a button.

Decagon now offers an instrument in which the only time consuming process is loading the sample dish in preparation for measurement. Decagon continues to set the standard for speed and accuracy in water activity measurement. AquaLab Quantum is continuing proof of our determination to be the world leader in water activity technology.

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Measuring water activity with Pawkit keeps jerky safe but not overdried or flavorless.

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ANY FOOD PROCESSORS try to get control of their safety issues by measuring moisture content. But moisture content measurements are crude at best and misleading at worst. Moisture content is all about quantity--how much water. WATER ACTIVITY is about quality.

Microbes simply can’t grow.

WATER ACTIVITY tells you what the water in your product is doing.

Water in a product doesn't sit in a pool. Instead, it's "bound up" in various chemical bonds. And "bound" water is unavailable water--it's not "free" to be used by microbes and bacteria. In fact, if enough water is unavailable, microbes simply can't grow. That's why the Do the numbers and USDA guidelines state you’ll find water activity that: methods sum up to "A potentially hazardous product improvement. food does not include … a food with a WATER ACTIVITY value of 0.85 or less."

Safe water activity levels are the same for every recipe.

WATER ACTIVITY explains why salt acts as a preservative in food. When salt is added, moisture content stays the same. But some of that moisture is now chemically "bound" with the added salt. Measure the WATER ACTIVITY and you'll find that it's lower.

"Safe" moisture content levels are different for every food and every recipe. Safe WATER ACTIVITY levels are the same for every food and every recipe. WATER ACTIVITY gives you a snapshot of what water is doing inside your product--and lets you tailor your processing to maximize both profits and product quality.

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Sign up for a no-obligati Pawkit Water Activity M

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OM STABOSZ of Toxic Tommy's Beef Jerky (www.ToxicTommy.com) was dehydrating his jerky to 165 degrees F. Proving every batch was getting up to temperature satisfied the inspector. But it was driving Tom crazy.

"I [was] tired of sticking temperature probes into 3/16" sliced piece of drying meat in an open oven and hearing the inspector say … not 165 yet!" Tom wanted a simpler and quicker solution. He decided to check out water activity using Pawkit.

Water activity—the magic number.

The USDA says any food with a water activity of less than 0.85 complies with the non-potentially hazardous food regulations. (If you are still measuring moisture content you probably haven't heard of water activity - check the sidebar) Get the whole picture with water activity.

At water activities that low, dangerous microbes don't grow. Water activity is a quick, reliable safety check. And Pawkit is a simple, fast, portable meter that lets you check water activity at the production line.

Get a quick picture of your water activity.

Pawkit is like a little point and shoot camera--it gives you a quick and accurate picture of food quality and safety. Just pop a sample into the disposable sample dish, flip open Pawkit, slide in the dish and get a measurement in 5 minutes. By making these safety snapshots routine on your production line, you assure yourself and any inspector that every product coming out of your oven is safe.

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ion demonstration of Meter today.

Pawkit in the pocket equals money in the bank.

Over processed food means higher ingredient costs, higher electric bills, higher labor costs, and often a product that just doesn't taste as good. Tom discovered that by checking water activity, he could save at least 20 minutes of processing time for each production run and yield a more consistent, higher quality product. He figures the Pawkit gives him a 10% productivity improvement. He's reduced electricity, labor, and production costs. And ingredient costs are down—by shipping a higher moisture product, he's improved his profit margin AND his product quality. The moister product has a longer shelf life, minimizing returns, exchanges, and credits.

Tom estimates that Pawkit will pay for itself in less than a year.

Don’t wait for a rainy day to get Pawkit.

A leaky roof isn't cheaper than a good roofing job.

You know you'll have to pay way more down the road. It's hard to make an investment sometimes, even when you know it will save you a lot over time. We can help fit Pawkit into your testing program. In addition to demo instruments like the one Tom used, we have interest-free payment plans that let you schedule payments so Pawkit really can pay for itself.

Plump up your profits.

Give us a call. At no charge, we can evaluate your particular operation and estimate how much Pawkit will save you. No obligation in that toll-free callwe'll help you get the information you need to plump up your product and your profits.

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Frequently Asked Questions 1 Will USDA inspectors accept water activity measurements?

Water activity standards are written into the USDA definitions of potentially hazardous foods. The USDA prefers water activity measurements to prove compliance--but individual inspectors may not have experience with water activity. If the inspector at your facility has questions, we'll be glad to provide the scientific and USDA documentation he or she needs to understand the validity and importance of water activity measurements.

2 Can Pawkit survive rough conditions?

Pawkit is a sensitive instrument—but it's also tough. It was built to be used on the line. It has a one year parts and labor warranty, and an extended warranty is available.

Get a handle on water activity numbers and improve your products.

3 Isn’t water activity too technical for my small operation?

Anyone who can use a thermometer or a camera can handle Pawkit. Water activity measurements are commonly made by food scientists in labs—but they are also routinely made by regular folks as a routine part of processing. Pawkit is like a little point-and-shoot camera—simple to use by anyone. And the results have all the accuracy and resolution you need to make safety decisions at the production line.

4 Isn’t contract lab testing cheaper?

Outside tests cost $25–$50 per test, a big expense when added up over time. Also, you have to package and send samples, then wait up to a week for results. Using Pawkit to take your own water activity "snapshots" saves money and time. You make your own decisions right at the line. In addition, you can test many inprocess samples rather than just sending out a final lot check.

5 What about calibration?

No need to put your product safety on the chopping block.

Get Pawkit to measure water activity.

Pawkit's two-point calibration is quick and easy. We provide a set of Performance Verifications Standards for calibration and accuracy checks. Pawkit also comes with 100 free disposable sample cups and a carrying case.

For a free Pawkit demo, call 800-755-2751 today.

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Water Activity and Pet Foods

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Mold growth is the form of spoilage most frequently observed in dry pet foods. Preventing growth and toxin production from microorganisms is a goal for manufacturing of stable and safe pet foods.

Once the optimal a w is found for a product, extreme temperature and humidity during storage, which will change a product’s a w , should be avoided to prevent microbial growth. Water activity, not water content, determines the lower limit of available water for microbial growth.

The lowest a w at which the vast majority of food spoilage bacteria will grow is about 0.90, with the exception of Staphylococcus aureus In fact, water activity has been an which has a limit at 0.86 a w under important parameter in commercial pet foods aerobic conditions. The practical limit since the late 1950’s. Soon after Scott for growth of yeast is 0.88 and for (1957) showed that microorganisms have molds is 0.70 a w , although some a limiting water activity level below xerophilic molds and yeast will grow which they will not grow, scientists below 0.70 a w . The lower limit for all were looking for other practical microbial growth is 0.60 a w . Toxins, application of a w . One of the first notably mycotoxins in the case of products fully developed using feeds or raw materials, may be water activity technology was formed during mold growth but not “Gainesburgers” made by General below 0.80 a w .

Foods Corp. Gainesburgers were The pet food and feed industries an intermediate moisture dog food have long used water activity to create novel products and predict shelf life, Insects are another that were promoted as “the safety, and quality. significant potential source of canned dog food without the can”.

Quaker Oats Company followed in the mid-1960’s by product or raw material deterioration and in some cases can be controlled using a w. For example, mite introducing a shelf-stable, intermediate-moisture activity is dependent on water activity and marbled meat pet food. Water activity technology temperature. Mites may be active at 5°C above provided the means to form a soft, elastic, marbled 0.65 a w , at 25°C above 0.63 a w , and at 40°C above product resembling meat. This highly successful dog 0.60 a w . Many species need a water activity of not food is reported to have generated more profit per less than 0.65 for development. Therefore, square foot of display shelf space than any other maintaining a product or raw material water activity product. below 0.60 should minimize the risk of mite activity.

There are a number of products on the The pet food and feed industries have market with multi-textured characteristics that use water activity. These products combined a hard, dry- long used water activity to create novel products baked pet food and a soft, moist pet food. The hard, and predict shelf life, safety, and quality.

Determination of water activity during manufacture dry component has the advantage of teeth cleaning, allows tight control of pet foods and feedstuffs but is less palatable than a soft, moist food. The found to be at high risk for deterioration. Without the soft, moist component may be highly palatable, but lacks the abrasive teeth cleaning property. When the use of water activity, the pet food industry would have a hard time developing innovative products or two components are mixed, they equilibrate to a producing nutritious, high quality, stable food. common equilibrium water activity during storage.

This equilibrium a w must allow the dry component to remain hard and crunchy while leaving the soft component moist and tender.

ET FOOD AND ANIMAL FEEDS need to be nutritious, safe, and stable at a specified shelf life. Just like human food, pet diet components are susceptible to microbial, chemical, physical, and insect spoilage.

Water activity ( a w ) is one of the most important parameters in preservation, safety, and quality.

Water activity is a very practical tool in developing and producing nutritious, safe, and stable pet food because it is critical for microbial growth, texture, flavor, chemical reactivity (such as browning or lipid oxidation), or enzyme activity.

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From the International Desk: Water Activity Contest in Latin America Braseq Decagon

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ITH MORE THAN 100 AQUALAB units sold just in Brazil and hundreds of others in Latin America, Braseq Brasileira de Instrumentos Ltda., with headquarters in Sao Paulo, Brazil, decided that it was time to promote an water activity contest that would help unify the industry and academia, and emphasize the importance of aw in the region.

Braseq invited scientists and researchers from the food, cosmetic, and pharmaceutical industries, as well as top universities and research centers from all over Latin America to present papers on water activity-related research.

A panel of experts formed by Braseq engineers, Decagon scientists, and Dr. Jorge Chirife, one of the world’s authorities in water activity, evaluated the top 22 papers, awarding a Pawkit® Portable Water Activity Meter to the top two papers. Dr. Chirife participated in the award ceremony and latter presented a seminar in aw applications for food products. The winners of the two most innovative studies using aw were “The Effect of the Cholesteric Structure on the Water Activity of Lyotropic Liquid Crystals” by Dr. Maria Regina Alcântara, from the Institute of Chemistry of the University of Sao Paulo (USP) and “Water Activity in Food Solutions” by Dr. Antonio J. A. Meirelles et al. from the Department of Engineering of Foods of the University of Campinas (Unicamp).

Both Braseq and Decagon received many compliments from the industry for this initiative. The program was very successful and opened the doors for innovative studies in areas of shelf life, microbial growth control, product development, etc.

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

KD2 for foods.

•Portable •Compact •Easy to use •Direct readout

Call today.

DECAGON

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

Drying Healthy Dog Food Fresh Bakery Transport Caking and Clumping Isotherm Comparisons Moisture Migration To recieve our free new booklet “Water Activity Tools: How to profit from proven productquality techniques in 5 quick lessons” Call now at 1-800-755-2751

WATER is the cheapest ingredient available. It doesn’t cost much to add water. Unless you add the wrong amount.

Then water can be incredibly expensive.

Add too much and your product will mold on the shelf. Get the amount wrong, and your product will lose its crunchiness or softness. For a cheap ingredient, water can cause a lot of expensive headaches.

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Water Activity News On-line downloads

Dear Customers,

We are celebrating 20 years in the water activity business. Time does fly when you’re having fun!

We’ve grown over the years but our commitment to you remains the same. We promise to deliver the best water activity measurement equipment available. My favorite part of the job is visiting with customers and having them tell us that they love our instruments.

Please let us know if we have not yet been able to take care of your water activity needs.

Sincerely,

Tamsin Campbell Product Manager

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E ARE PLEASED to announce our new series of videos. These videos will demonstrate AquaLab and Pawkit instrument cleaning and maintenance. Each video is only a few minutes long and is intended to provide visual instructions to help increase understanding of cleaning and operation of our instruments.

We have found that 40% of the instruments sent to us for repair are actually only in need of cleaning. We know your time is valuable. Therefore, we feel that if cleaning an instrument is better understood, it will save your company time, money, and valuable resources by simply not having to send the instrument in for repair.

This video is free, comes on a CD, and is now available. If you have not yet received yours and would like one, please feel free to give us a call and order. Or email us at sales@decagon.com.

Free cleaning video for AquaLab and Pawkit.

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Let us introduce downloads available to you from the AquaLab web site. There are downloads regarding Water Activity information, Newsletters, Papers and Application Notes, and information on various instruments.

Water Activity information gives you general information about water activity theory and importance. Our newsletters provide excellent information geared toward what businesses need.

The papers and application notes provide specific information for certain applications. Whether it is Pharmaceuticals, Dry or Dehydrated products, or FDA’s guidelines, you will most likely find the information you need here. You will also find information for AquaLab instruments such as spec sheets, manuals, and quick start guides. We encourage you to take a look, it’s worth it!

This information can be a valuable asset to your company and you are welcome to download it anytime 24 hours a day. On the internet, simply navigate to http://www.aqualab.com/ download.html and double click on the download(s) of your choice.

New Service Contract We are pleased to introduce our new service contract. By September 1st, our new program will be in full swing. Our promise, “handheld instruments will be repaired in 24 hours, and bench top instruments in ten days or less.” There is even better news. Our records show that over 40% of time spent in repairs has been routine cleaning procedures you could have performed yourself. Chances are, our new cleaning video (see opposite column) will resolve your concerns with no expense or wasted down time. If you do need to send an instrument in, ask about our loaner program when you call. Customer service has always been a priority at Decagon, now we’re committed to be faster, too.

CALL TODAY! Decagon Devices, Inc. publishes Water Activity News annually.

No subscription or dues.

ISSN# 1083-3943.

Printed in USA. ©2003 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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