Water Activity News 2007

www.aqualab.com

WaterActivityNews 2007 History of Water Activity Measurement

T

he concept of water activity is slightly over fifty years old. It was Scott in 1953 who showed that microorganisms have a limiting water activity level for growth. Water activity, not moisture content, is now well accepted as a property to predict the stability and safety of food with respect to microbial growth, rates of deteriorative reactions and chemical/physical properties. Water activity testing is now a rapid, accurate, and easy test used by many companies for food formulation, process control, ingredient inspection, and quality control.

But this was not always the case with measuring water activity in foods.

Throughout the 50 years of water activity in foods, a large number of methods and instruments have been described in literature. This article is not a review of the literature on water activity measurement, but rather a highlight of some key water activity methods and instruments. Many early water activity methods were developed prior to Scott’s work and are adaptations of atmospheric humidity measurement or techniques to measure the water potential of soil. There is no device that can be Water activity is a continued on page 8 Z

Water Activity for Monitoring the Quality of Dried Distillers Grain

D Monitoring water activity will save you more than chicken feed.

D

DECAGON DEVICES

ried Distillers Grain with Solubles (DDGS) is a co-product of the grain bio-ethanol manufacturing process. It is created through a multistep process. First, the non-fermentable material leftover from ethanol production is removed as stillage. Excess water is removed from the stillage by centrifugation and the wet grains are combined with condensed distillers solubles and dried to create DDGS. It is sold primarily as a high quality feed supplement, but could potentially have many uses including as a nutritional supplement for humans. The sale of DDGS contributes substantially to the economic viability of an ethanol production plant. Consequently, optimization of DDGS quality and shelf-life are of utmost importance.

Recommended Analytical Methods for DDGS On February 1, 2007, the American Feed Industry Association released a study titled “Evaluation of Analytical Methods for Analysis of Dried Distillers Grains with Solubles.” This study examined analytical method efficacy for evaluating DDGS. The objectives of the study were to choose a set of tests that would best characterize the physical and chemical characteristics of continued on page 2 Z

familiar tune, playing since the 1950’s, for determining food safety.

CONTENTS History of Water Activity Measurement Pg 1 Water Activity for Monitoring the Quality of Dried Distillers Grain Pg 1 Dear Anthony, Pg 4 Oak State Products keep their cookie’s shelf-life on target with water activity.

Pg 7 New Mexico Prevents Salmonella with Water Activity Education Pg 10 Automatic Re-order Pg 12 Water Activity Seminar Schedule Pg 12

1

aw

Water Activity for Monitoring i continued from cover

Trade Shows 2007 & 2008 Intl Symposium on the Properties of Water (ISOPOW) Bangkok, Thailand September 2 – September 7, 2007 FI Europe ExCel London, England October 30 – November 1, 2007 American Association of Pharmaceutical Scientists San Diego, CA November 11 – 15, 2007 Eastern Analytical Symposium Somerset, NJ November 12 – 15, 2007 Food Safety Summit Washington DC March 17 – 19, 2008 National Environmental Health Association Tucson, AZ June 22 – June 25, 2008 IFT Annual Meeting and Food Expo New Orleans, LA June 28 – July 2, 2008 International Association of Food Protection Columbus, OH August 13 – 16, 2008 2

DDGS and ensure its safety and quality. The main concerns for DDGS shelf life are susceptibility to microbial degradation, maintaining flow properties, and moisture migration.

Water Influences All of These Concerns In this study, the only moisture analysis method listed was moisture content. Unfortunately, moisture content is not the most effective moisture analysis method for the concerns listed above. Water activity is a better predictor of microbial safety, flow properties, and moisture migration. Ethanol producers will have more success ensuring the quality of their DDGS product while saving time and money if they use water activity as one of their quality assurance tests.

What is Water Activity?

Water activity represents the energy status of the water in the system and is equal to the relative humidity of the air in equilibrium with a sample in a sealed chamber. It is based in thermodynamics and is defined as the vapor pressure of water (p) over a sample divided by the vapor pressure of pure water (po) at a given temperature. Though not scientifically correct, it may help to picture water activity as the amount of “available” water in DDGS. It is not determined by how much water is present in DDGS, but is a comparison of how much the water in DDGS resembles and behaves like pure water.

Water activity values represent a scale that ranges from 0 (bone dry) to 1.0 (pure water).

As water activity decreases, the water in DDGS decreases in energy, is less available, and behaves less and less like pure water. For example, a water activity of 0.80 would indicate that water in the system has enough energy to support mold growth while a water activity less than 0.60 means that the water in the system cannot support the growth of any microorganisms. Water also becomes more mobile as water activity increases, which influences molecular mobility and increases chemical and enzymatic reaction rates. For example, browning reactions rates will be minimal at a water activity of 0.25, steadily increase as water activity increases, and reach a maximum at about 0.80 aw.

the Quality of Dried Distillers Grain Water Activity Controls Microbial Growth The water activity concept has served microbiologists and food technologists for decades and is the most commonly used criterion for food safety and quality. Microorganisms have a limiting water activity below which they cannot grow. Water activity, not moisture content, determines the lower limit of “available” water for microbial growth.

Since bacteria, yeast, and molds require a certain availability of water to support growth, drying DDGS below a critical aw level provides an effective means to control microbial growth. Water may be present, even at higher content levels than normally acceptable in DDGS, but if its energy level is sufficiently low, the microorganisms cannot utilize the water to support their growth. This ‘desert-like’ condition creates an osmotic imbalance between the microorganisms and the local environment.

Consequently, the microbes become dormant or die.

The water activity level that limits the growth of the vast majority of pathogenic bacteria is 0.90, a water activity of 0.70 is the limit for spoilage molds, and the lower limit for all microorganisms is 0.60.

Water Activity Helps Control Caking, Clumping, Collapse and Stickiness Water activity can also be an indicator of physical stability of DDGSs during storage. Due to its impact on ease of handling, flowability is a major physical stability concern for DDGS. Controlling water activity in DDGS maintains proper structure, texture, stability, and density. A critical water activity can be identified below which DDGS will maintain its flow properties. Above this critical water activity, the DDGS particles are wetted and begin to stick together. Consequently, knowledge of the water activity of DDGS as a function of moisture content and temperature is essential during processing, handling, packaging and storage to prevent the deleterious phenomenon of caking, clumping, collapse and stickiness. Water activity is the most effective quality assurance test available to assess the susceptibility of DDGS to reduced flow properties.

Water Activity Controls Moisture Migration Because water activity is a measure of the energy status of the water, differences in water activity are continued on page 6

Is it time for your annual calibration?

C

ertify your AquaLab is working within specifications with Decagon’s Factory Calibration Service. The Calibration Certificate is suitable as documentation for USDA and FDA compliance of GMP and HACCP. AquaLab Calibration Service includes:

Factory Cleaning and Calibration.

Dated Certificate of Calibration.

Loaner AquaLab to keep you up and running.

72-hour turnaround.

Free Shipping.

Unlimited Toll-Free Technical Support

“Thanks so much for your time. I must tell you, I came back from your seminar so enthusiastic that the F.S.I.S. inspectors are avoiding having any discussions about water activity with me. That alone is worth the price of the seminar!”

Gary Towle Towle’s Saugany Lake Smokehouse

3

D

DECAGON DEVICES

Dear Anthony,

I am trying to make a shelf-stable meat product and am confused by the term moisture/ protein ratios.

What is it and do I have to measure MPR? The main objective in making a shelf-stable meat product is to arrive at a combination of hurdles that inhibits undesirable microbial growth, while supporting desirable microbes in some fermented meat products. Some important hurdles for meat products are: water activity, pH, temperature, redox potential, preservatives, etc.

There are many combinations of hurdles that can achieve product stability. For example typical fermented sausages have been categorized as either; very perishable (pH > 5.2; aw > 0.95) perishable (pH 5.2-5.0 or aw = 0.95-0.91) shelf-stable (pH 5.2 and aw < 0.95 or only pH < 5.0 or only aw < 0.91) Another source for water activity and pH ranges for shelf-stable products is in the 2005 Food Code definition of Potentially Hazardous Foods Interactive Tables.

Moisture/protein ratios (MPR) are commonly used in the U.S. to classify dried sausages and other meat products.

These ratios express the percent moisture divided by the percent protein. Although the MPR values do indicate the degree of product drying, they are not correlated well to microbial safety or stability, as with aw values. Water activity is the most important single factor for shelf-stability (as indicated by microbial stability) of dried meats.

Regardless, the FSIS Food Standards & Labeling Policy Book still identifies criteria for a shelf-stable product based on MPR. These historic MPR values are based on average values of a market basket survey that representative products exhibited at the time of the initial classification. Shelf-stable dry sausage must have an MPR 1.9:1, jerky an MPR of

4

0.75:1, and semi-dry sausage must have an MPR 3.1:1 with a pH 5.0, or be commercially sterilized (unless another MPR is specified for a product).

In early Fall 2003, FSIS became aware that some manufacturers may be relying upon a maximum MPR rather than water activity for determining adequate drying. FSIS has clarified that MPR should not be used to verify proper drying for shelf-stable meat products. Instead, water activity, as measured by laboratory procedure, should be used to verify that proper drying has occurred to produce a shelfstable product. Therefore, water activity replaces MPR as a measure of dryness for food safety, but you may still have to measure MPR as part of the standard of identity for your shelf-stable meat product.

I have reformulated my product and lowered the water activity to 0.86, what is my shelf-life?

I am asked this question quite often, but am sorry to say that I cannot answer this question without more information. Many food products are required to have some type of open date, but how does one determine this date? The first piece of information necessary to determine the shelf-life of a food is to define what is and what is not an acceptable product. Many times there is an indication of product acceptability from your consumer complaint files, but most companies tend to focus on the characteristics of the best product instead of an unacceptable product.

Once you have a good feel for what the consumer considers as end-of-shelf-life, you need to understand the mechanism(s) responsible for the spoilage. There are many pathways for food spoilage, such as microbial growth, chemical degradation, enzymatic reactions, and physical property changes (texture, flavor, odor, organoleptic, etc.). Many times these spoilage pathways are occurring simultaneously. In addition, there are many factors such as formulation, processing, packaging, and storage conditions that have great influence on these mechanisms of spoilage. An understanding of the interaction

Water Activity Measurement

between these factors is key to shelf-life estimation.

Water activity has a pronounced affect on these spoilage pathways and mechanisms through its influence on microbial growth rates, chemical/ biochemical stability and physical properties of foods. For example, to make a shelf-stable product, you may have lowered the water activity to 0.86 for microbial control. But, if you lowered your product’s water activity by adding high fructose corn syrup (an inexpensive humectant and reducing sugar) and your product contains free amines from proteins or amino acids, then nonenzymatic browning will occur and you will see a color darkening and flavor change during storage. On the other hand, if you lowered the water activity using sucrose (a non-reducing sugar) then the browning reaction will not proceed and you would have a much longer shelf-life.

Therefore, an effort to enhance shelf-life by changing a single ingredient may lead to unexpected chemical or physical changes and require reformulation or a change in processing or packaging to obtain the desired shelf-life.

t n e l l e c Ex

“I just wanted to let you know how satisfied we are with your products and service. We have purchased 7

aw

machines from your company over the past 3.5 years and the performance and service has been excellent. We are required to send our units in for a yearly inspection/calibration to comply with our food safety program and we have always received a loaner(s) for this exercise which is most helpful. As for performance of the units we use them up to 20 times per 24 hours per day/7 days per week and have experienced less than 1% downtime on all of our units. This level of performance is well beyond typical

Information is needed on the ingredients, formulation, processing conditions, packaging, and experimental data under abuse conditions in order to answer your question “What is my shelf-life?”.

Accelerated shelf-life testing is where finished product is monitored under abuse conditions until unacceptable. The abuse conditions are typically, higher temperature and relative humidity (or water activity). Decagon’s SafeStorage Monitor for inpackage water activity/temperature logging is ideal for collecting this type of data. The accelerated shelflife data is then used to project shelf-life under normal storage conditions. Models that incorporate the effect of temperature and water activity are excellent for shelf-life predictions of moisturesensitive foods.

performance of electronic devices. I would definitely recommend your products to other customers.”

—Terry C. Llewellyn Jr. Plant Manager Kettle Valley Dried Fruit A SunOpta Company

www.aqualab.com 5

| D

DECAGON DEVICES

Advertisement

New Product AquaSorp Isotherm Generator Quality of Dried Distillers Grain

continued from page 3

the driving force for moisture migration. Knowledge of whether water will absorb or desorb from within a load of DDGS is essential to prevent degradation.

Thus, water activity is an important parameter since it can control water migration in mixed lots of DDGS. Different loads of DDGS could have different water activities due to variation in drying conditions and amount of added solubles. By definition, water activity dictates that moisture will migrate from a region of high aw to a region of lower aw, but the rate of migration depends on many factors.

THOUGHT QUESTIONâ&#x20AC;&#x201D;If equal amounts of one load of DDGS at 15% moisture and a second load at 15% moisture content are blended together, will there be moisture exchange between the loads?

6

NOW AVAILABLE

The answer depends on the water activities of the two loads. If the water activities of the two loads are the different, then moisture will be exchanged, even

though their moisture contents are the same. This moisture migration could lead to flow or microbial growth problems.

Conclusion Water activity is an effective process control and quality assurance tool for maintaining the stability and safety of DDGS and should be included as a recommended analytical method for DDGS. In addition to the reasons outlined above, water activity is a more effective moisture analysis than moisture content because it is more sensitive and accurate. In the intermediate moisture region, which includes DDGS, changes in moisture content that are undetectable due to the limited accuracy of moisture content analyses can result in large changes in water activity and consequently, changes in stability. This can be disconcerting when DDGS are dried to a moisture content specification and stability changes suddenly occur even though a moisture content change is not detected. These stability changes can be predicted if a water activity specification is used.

Water activity is a fast, inexpensive, and accurate way of assuring the quality and safety of DDGS. It can easily be incorporated by any ethanol plant. If interested in learning more about water activity testing and DDGS, please contact Decagon.

|

Oak State Products keep their cookie’s shelf-life on target with water activity.

O

ak State Products makes cookies. Lots of them. They make them crunchy, soft, high fat, low-fat, full of fiber, and ground up as inclusions in ice cream and candy. In fact, Oak State has made, is making, or will make cookies for nearly every major cookie label. They make what the customer wants, and that starts with formulation in David Busken’s lab.

From Concept to Market Busken is Manager of Research and Development at Oak State Products. They bill themselves as taking quality products “from concept to market.”

“Customers come to us with a concept, and we grow or refine that concept,” he says. “They tell us what they want—longer shelf life, a particular protein or fiber content—and we do the formulation.” Often, figuring out how to make what the customer wants involves working with water activity.

Go Too High, You’ll Get Mold Products made to be stocked on grocery store shelves need a shelf life of six months, and that can get tricky with a soft cookie. “Water activity is critical in soft cookies,” he says. “There’s been lots of R & D on how to keep cookies softer longer. We need to put moisture into the product and hold it there without making the water activity too high. You have to get the moisture in there, but if you go too high, you get mold.”

Soluble Fibers Absorb More Water Busken says he will typically “work up a formula, make it up in the lab, bake it off, look at the water activity, then hold it and see how it ages.” Some

T S E B

ingredients make formulation tougher.

Fibers, for example, are “notorious.

Fibers, especially soluble fibers, suck up a lot of water. You put enough water in to get the right viscosity of the dough, and boom! The water activity is through the roof.” Then with soft cookies, “the bake is critical. You can bake them enough to set up, but only water activity will tell you if you’ve baked it out enough. If the water activity is still too high, you’re going to have to do something about it.”

“They tell us what they want—longer shelf life, a particular protein or fiber content—and we do the formulation.”

Water Activity Data is Required Water activity measurements are not just critical in the lab. Nearly all of Oak State’s customers demand water activity data, and most products must meet water activity specifications. “You can’t run without water activity,” says Busken. “If all the water activity [instruments] broke down, some lines could still run, but most would be shut down. You have to know where you’re at on water activity before you say ‘We’re good to go.’”

“I enjoyed very much your seminar on Fundamentals of Water Activity. It was the best one day seminar I have attended. I now have a basic understanding of water activity. I didn’t realize the importance of water activity in product quality and safety. The seminar kept my interest to the very end. Thank you once again for all your help.”

Elizabeth Pappas Analytical Chemist

7

History of Water Activity Measurement i continued from cover put into a food to directly measure water activity.

Rather, aw is measured with a technique that directly or indirectly measures vapor pressure or some parameter relatable to vapor pressure. The methods and instruments vary in accuracy, repeatability, speed of measurement, stability in calibration, linearity, and convenience of use.

Scott, in his pioneering studies on the relationship between aw and microbial growth, used a bithermal equilibration apparatus as shown in Figure 1. The method and apparatus was originally described by Stokes in 1947 and was used to determine the water activity of saturated salts, which are still used as reference tables today. Because Scott used this method and the saturated salt tables, it has been stated that if there is such a thing as a reference method for aw determination it is probably the bithermal equilibration technique. Although not a fast technique, it did produce accurate water activity measurements with good temperature control and measurement. Water activity was calculated from the ratio of vapor pressure read from psychrometric tables at the two temperatures.

Figure 2. Vapor pressure manometer from Troller, JA & Christian JHB 1978, Water Activity and Food, Academic Press, NY pp13-47.

Over the years a category of water activity measurement techniques based on the moisture sorption isotherm of either the food sample itself or a reference material have been used. These methods include: isopiestic equilibration, graphical interpolation, and salt impregnated filter paper. One of the main advantages of these techniques is that they require very inexpensive equipment and supplies. Only a desiccator, salt, and balance are needed. Figure 3 is an illustration of an isopiestic equilibration chamber.

However, they require long equilibration times and thus are not practical for routine or quality control testing. Over the years improvements in these techniques have appeared but they still require 1 to 24 hours to measure water activity.

Figure 3. Isopeistic Equilibration Chamber

Figure 1. Bithermal equilibration apparatus. from Troller,J. 1982. J. Food Prot. 46(2):129-134.

Another early method was the direct measurement of the vapor pressure of foods using manometry.

Makower and Myers in 1943 demonstrated this technique for foods, but erroneously equated the vapor pressure to total moisture. A vapor pressure manometer is shown in Figure 2. With good technique and temperature control, these instruments have relatively high reported precision (Âą0.002aw).

They are relatively inexpensive, but unfortunately are cumbersome and extremely fragile.

8

In the 1960s and early 1970s, companies began designing and developing intermediate moisture foods using water activity technology.

Commercial instruments designed specifically to measure water activity of foods began to appear.

These instruments and devices include: hair or polymer hygrometer, freezing point depression, thermocouple psychrometry, electric hygrometer, and chilled mirror dewpoint (see sidebar for illustrations of the instruments and sensors). These early instruments were still slow to equilibrate (requiring 1 to 24 hours), had limited measurement range, and were accurate to no better than 0.02aw. Electric hygrometer sensor technology improvements through the 1970 and into the 1980s reduced the

s k n Tha

“I wanted to thank both of you for an incredibly detailed and absorbing seminar! I can’t say enough good things about it. I wish my entire QA team could attend!”

measurement time to approximately 30 minutes with a ±0.015aw accuracy. Not until 1987, when Decagon Devices introduced the AquaLab chilled mirror dewpoint water activity meter with it’s <5 minute measure time and ±0.003aw accuracy, did measurement become practical for quality and process control.

In 2000, Near Infrared Spectroscopy (NIR) was applied to water activity. NIR is used to measure moisture, fat, protein, carbohydrates, and ash in many food products, however, aw by NIR is a new concept. NIR water activity measurement consists of using a spectrometer and chemometrics software to first form a calibration curve for a particular product, and then using that calibration curve to rapidly predict the water activity of further samples.

Decagon has commercialized this technology and scientists at Decagon have made calibrations for many different food types with ±0.01aw accuracy.

There are several potential advantages to using a NIR system: 1) Water activity measurement using NIR is nearly instantaneous, which would vastly reduce the time spent on product analysis. 2) The NIR method can be applied to a wider array of applications, such as on-line analysis of products.

3) NIR measures the water in the product not the air that is equilibrated with the product.

With technological improvements, the time required for water activity measurement 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 and using NIR technology, the analysis time is now 6 seconds.

Michael P. Pappas Quality Assurance Manager Rich Products – Wheeling

Commercial Water Activity Instruments and Sensors

Hair hygrometer from Troller, JA & Christian JHB 1978, Water Activity and Food, Academic Press, NY pp13-47.

Thermocouple psychrometer.

SafeStorage Electric hygrometer sensor.

AquaLab Lite Electric hygrometer sensor.

Pawkit Electric hygrometer sensor.

AquaLab Dewpoint sensor.

What does the future hold?

9

New Mexico Prevents Salmonella with Water Activity Education

I

n 2003, beef jerky was implicated in a Jerky Producers Want Food Safety nationwide outbreak of Jerky manufacturers are an especially salmonella. The jerky important group to train because of producer—a New Mexico the risk of foodborne illness company—had to recall 22,000 associated with beef jerky. A unique pounds of product and live with the form of jerky, carne seca, is popular resulting negative publicity. Jonathan in New Mexico. Gerhardt works Gerhardt, one of five Food Specialists with manufacturers to increase their at the New Mexico Environment knowledge of food safety factors for Department (NMED), is committed to jerky. “In New Mexico, beef jerky protecting public health and helping producers must be certified by NMED New Mexico food producers avoid similar and the New Mexico Livestock Board. situations. He spends a great deal of time The Livestock Board operates in For jerky products, educating producers about safe food conjunction with the United States what is dry enough to production. He also trains food inspectors Department of Agriculture.” be safe? to properly inspect and test food to ensure it meets state standards.

Safety and Moisture-Protein-Ratio.

Historically, the Livestock Board required moistureEducation on Water Activity protein-ratio (MPR) measurements rather than water Gerhardt considers water activity measurements an activity to assure shelf-stability for beef jerky. When I important tool in determining whether a product is began to work with jerky sellers in 2002, some were safe for consumption. However, he acknowledges not familiar with the water activity requirement in that many small producers in the industry do not state Food Regulations or the significance of water have a solid understanding of water activity. “[They] activity for the safety of their products. The jerky may know that 0.85 is the maximum water activity manufacturers were not adequately educated allowed in their product but they can not explain the concerning water activity and the Livestock Board role water activity plays to make their product shelf- was measuring MPR, not water activity.” stable and safe.”

H

Z

English provender company uses water activity meter for quality control and new product development.

From the International Desk

T

he English Provender Company specializes in manufacturing premium-quality condiments, sauces, dressings, marinades and similar products for the retail, foodservice and food manufacturing markets in the UK and beyond.

Artificial colouring, flavourings and preservatives are not used, so the company has to take particular care to ensure that its products remain stable and will not spoil prior to use. One of the ways this is done is by using a computer model to predict stability. However, this requires a value for the product’s water activity (or ERH), and The English Provender Company was finding that it was expensive ad time-consuming to have this measured

10

by an external laboratory. Having purchased an AquaLab Series 3TEB from Labcell, the company’s quality assurance team is now able to carry out measurements of water activity in-house, plus the same instrument is being used by the product development team.

Eleven members of the quality assurance team use the AquaLab on a regular basis to measure water activity. This is important for the company’s emulsified mayonnaise-based products, such as tartare, horseradish and seafood sauces. Further more as well as the tests performed on samples taken from the production line, ‘abuse’ tests are performed, with samples incubated at elevated temperatures for four weeks to check that the products will not spoil if stored in non-ideal conditions.

Z

I

Portable Water Activity Meter Gerhardt uses a portable meter to check water activity during site visits. These visits give him a chance to educate others about water activity.

“When I am asked to accompany an inspector for an on-site visit, I see it as an opportunity to not only correct operational violations but also to offer further training to the manufacturer.” The portable meter gives him a chance to check water activity onsite. “As a regulator, a major benefit of having a portable meter is being able to conduct on-site water activity testing of products just off the production line to ensure the product has achieved the required 0.85 or less.” Gerhardt also uses the portable meter to verify water activity with manufacturers

DECAGON DEVICES

developing products who have asked for advice or guidance. He sees a portable meter as a helpful tool for industry as well.

“Owning a portable meter can benefit a company in the development of a process to test the safety and quality of the final product. It can also be extremely helpful by providing on-site verification of water activity on a daily basis.”

Water Activity is Critical.

Ultimately, Gerhardt’s goal is for every Food Specialist in the New Mexico Environment Department to have a portable water activity meter.

“New Mexico is divided into districts and ideally, there should be one meter in each district,” he explains. “The specialists would each have their own meter readily available for use during a consultation or inspection.” In the meantime, the other specialists can borrow his meter when necessary. The ability to test water activity is critical because “water activity is a scientifically proven food safety measure that will help protect the safety and quality of shelf-stable products and the consumers who purchase them.”

a

USDA and Water Activity “Water activity is a key food safety component for shelf-stable products like beef jerky,” Gerhardt explains. “When working with jerky manufacturers, I spend a considerable amount of time discussing water activity and its significance to maintain the safety and quality of a shelf-stable product. I spend time explaining that water activity at or below 0.85 has been scientifically proven to prohibit the growth of bacteria in products such as beef jerky.”

D

www.aqualab.com While the primary reason for purchasing the water activity meter was quality assurance, the AquaLab is also playing an important role in new product development projects. By measuring water activity and using this data in a stability prediction model, the food scientists can gain a level of confidence that new products are safe and stable before committing to factory trials. This avoids unnecessary trials that would be costly and time-consuming.

Carl Steckerl, the Head of Technical at The English Provender Company, comments: “We looked at several alternative water activity meters before selecting the AquaLab, and we are very pleased with it. It is easy and quick to use, it gives consistent results, the response time is good and it is straightforward to clean. Initially, we had some

queries, but Labcell arranged for some validation trials to be carried out in the USA.” Indeed, Carl Steckerl is very complimentary about the service he has received from Labcell: “They were very helpful when we made the initial enquiry and then, after we decided to purchase the AquaLab, they delivered it, set it up, briefed us and carried out some training – though very little training is needed, as it is very simple to use.”

In conclusion, Carl Steckerl says: “After three months, the AquaLab is proving to be just what we needed. It is robust and reliable, and the only attention it requires is the weekly calibration, which is quick and easy.”

11

Water Activity News 2007

Automatic Re-order:

Dear Customer,

Your Life in the Lab Just Got Easier

T

he past year has been a good one for Decagon and we hope that it has been a good one for you. We have moved into a new building (across the street from our old one) and made great strides in new product development. We are proud to announce a new instrument, AquaSorp IG (Isotherm Generator). This device will automatically create a moisture sorption isotherm, both the adsorption and desorption curves, in about a day. Instruments have been commercially available previously but were typically unaffordable for the main stream researcher. AquaSorp is priced to make this technology more broadly obtainable.

We would like to thank you for your business. If you have any comments or questions concerning Decagon products, please let me know personally at tamsin@decagon.com.

Tamsin Campbell President

Fundamentals of Water Activity Seminar Schedule

Pharmaceutical Trumbull, CT October 11, 2007

12

If you are interested in setting up an ARS schedule, give us a call. You’ll never run out of cups or standards again!

D

DECAGON DEVICES

West Coast: Pullman, WA September 27, 2007

East Coast: Foods Trumbull, CT October 10, 2007

Many of our customers already participate in ARS—it involves setting up a simple one-year blanket purchase order with scheduled release dates. Your ARS schedule is flexible, so you can adjust it if your needs change. Current ARS users are enthusiastic about submitting just one PO per year.

ARS prices for sample cups and verification standards reflect the multiple-box discount, even if you only receive one box per release. Normal shipping charges and taxes (for customers in WA, IN, and SD) apply.

Sincerely,

Midwest: Chicago, IL October 2, 2007

E

very day we get orders from anxious customers who are down to their last AquaLab sample cup or verification vial. It would be ideal if we could “beam” them a box instantly. Decagon’s Automatic Re-order System (ARS) is the next best thing!

E

on r g ca ina e D m e S

Decagon Devices, Inc. 2365 NE Hopkins Court Pullman, Washington 99163 USA 1-800-755-2751 509-332-2756 Fax: 509-332-5158 aqualab@decagon.com

©2007 DECAGON PRINTED IN USA

www.decagon.com