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CONTENTS

History of WaterActivityMeasurementPg 1

Water Activity forMonitoring theQuality of DriedDistillers GrainPg 1

Dear Anthony,Pg 4

Oak State Productskeep their cookie’sshelf-life on targetwith water activity.Pg 7

New Mexico PreventsSalmonella withWater ActivityEducationPg 10

Automatic Re-orderPg 12

Water ActivitySeminar SchedulePg 12

� Water activity is afamiliar tune, playingsince the 1950’s, fordetermining foodsafety.

www.aqualab.com

2007

DDECAGONDEVICES

Dried Distillers Grain with Solubles (DDGS)is a co-product of the grain bio-ethanolmanufacturing process. It is created through a multi-

step process. First, the non-fermentable material leftover fromethanol production is removed as stillage. Excess water isremoved from the stillage by centrifugation and the wet grainsare combined with condensed distillers solubles and dried tocreate DDGS. It is sold primarily as a high quality feedsupplement, but could potentially have many uses including asa nutritional supplement for humans. The sale of DDGScontributes substantially to the economic viability of anethanol production plant. Consequently, optimization of DDGSquality and shelf-life are of utmost importance.

Recommended Analytical Methods for DDGSOn February 1, 2007, the American Feed Industry Associationreleased a study titled “Evaluation of Analytical Methods forAnalysis of Dried Distillers Grains with Solubles.” This studyexamined analytical method efficacy for evaluating DDGS. Theobjectives of the study were to choose a set of tests that wouldbest characterize the physical and chemical characteristics of

Water Activity forMonitoring the Qualityof Dried Distillers Grain

The concept of water activity is slightlyover fifty years old. It was Scott in 1953who showed that microorganisms havea limiting water activity level forgrowth. Water activity, not moisture

content, is now well accepted as a property topredict the stability and safety of food with respectto microbial growth, rates of deteriorative reactionsand chemical/physical properties. Water activitytesting is now a rapid, accurate, and easy test usedby many companies for food formulation, processcontrol, ingredient inspection, and quality control.But this was not always the case with measuringwater activity in foods.

History of Water Activity MeasurementThroughout the 50 years of water

activity in foods, a large number ofmethods and instruments have beendescribed in literature. This article isnot a review of the literature on wateractivity measurement, but rather ahighlight of some key water activitymethods and instruments. Many earlywater activity methods weredeveloped prior to Scott’s work andare adaptations of atmospherichumidity measurement or techniquesto measure the water potential ofsoil. There is no device that can be

continued on page 2 Z

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WaterActivityNews

� Monitoring wateractivity will save youmore than chicken feed.

2

DDGS and ensure its safety and quality. The mainconcerns for DDGS shelf life are susceptibility tomicrobial degradation, maintaining flow properties,and moisture migration.

Water Influences All of These ConcernsIn this study, the only moisture analysis methodlisted was moisture content. Unfortunately, moisturecontent is not the most effective moisture analysismethod for the concerns listed above. Water activityis a better predictor of microbial safety, flowproperties, and moisture migration. Ethanolproducers will have more success ensuring thequality of their DDGS product while saving time andmoney if they use water activity as one of theirquality assurance tests.

What is Water Activity?Water activity represents the energy status of thewater in the system and is equal to the relativehumidity of the air in equilibrium with a sample in asealed chamber. It is based in thermodynamics and isdefined as the vapor pressure of water (p) over asample divided by the vapor pressure of pure water(po) at a given temperature. Though not scientificallycorrect, it may help to picture water activity as theamount of “available” water in DDGS. It is notdetermined by how much water is present in DDGS,but is a comparison of how much the water inDDGS resembles and behaves like pure water.

Water activity values represent a scale thatranges from 0 (bone dry)to 1.0 (pure water). As water activity decreases, the water in DDGSdecreases in energy, is less available, and behaves lessand less like pure water. For example, a wateractivity of 0.80 would indicate that water in thesystem has enough energy to support mold growthwhile a water activity less than 0.60 means that thewater in the system cannot support the growth ofany microorganisms. Water also becomes moremobile as water activity increases, which influencesmolecular mobility and increases chemical andenzymatic reaction rates. For example, browningreactions rates will be minimal at a water activity of0.25, steadily increase as water activity increases,and reach a maximum at about 0.80 aw.

Water Activity for Monitoringawi continued from cover

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Intl Symposium on the Propertiesof Water (ISOPOW)Bangkok, ThailandSeptember 2 – September 7, 2007

FI Europe ExCelLondon, EnglandOctober 30 – November 1, 2007

American Association ofPharmaceutical ScientistsSan Diego, CANovember 11 – 15, 2007

Eastern Analytical SymposiumSomerset, NJNovember 12 – 15, 2007

Food Safety SummitWashington DCMarch 17 – 19, 2008

National Environmental HealthAssociationTucson, AZJune 22 – June 25, 2008

IFT Annual Meeting and Food ExpoNew Orleans, LAJune 28 – July 2, 2008

International Association of FoodProtectionColumbus, OHAugust 13 – 16, 2008

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Water Activity Controls Microbial GrowthThe water activity concept has servedmicrobiologists and food technologists for decadesand is the most commonly used criterion for foodsafety and quality. Microorganisms have a limitingwater activity below which they cannot grow. Wateractivity, not moisture content, determines the lowerlimit of “available” water for microbial growth.Since bacteria, yeast, and molds require a certainavailability of water to support growth, dryingDDGS below a critical aw level provides an effectivemeans to control microbial growth. Water may bepresent, even at higher content levels than normallyacceptable in DDGS, but if its energy level issufficiently low, the microorganisms cannot utilizethe water to support their growth. This ‘desert-like’condition creates an osmotic imbalance between themicroorganisms and the local environment.Consequently, the microbes become dormant or die.The water activity level that limits the growth of thevast majority of pathogenic bacteria is 0.90, a wateractivity of 0.70 is the limit for spoilage molds, andthe lower limit for all microorganisms is 0.60.

Water Activity Helps Control Caking,Clumping, Collapse and StickinessWater activity can also be an indicator of physicalstability of DDGSs during storage. Due to its impacton ease of handling, flowability is a major physicalstability concern for DDGS. Controlling wateractivity in DDGS maintains proper structure,texture, stability, and density. A critical wateractivity can be identified below which DDGS willmaintain its flow properties. Above this criticalwater activity, the DDGS particles are wetted andbegin to stick together. Consequently, knowledge ofthe water activity of DDGS as a function of moisturecontent and temperature is essential duringprocessing, handling, packaging and storage toprevent the deleterious phenomenon of caking,clumping, collapse and stickiness. Water activity isthe most effective quality assurance test available toassess the susceptibility of DDGS to reduced flowproperties.

Water Activity ControlsMoisture MigrationBecause water activity is a measure of the energystatus of the water, differences in water activity are

the Quality of Dried Distillers Grain

continued on page 6

“Thanks so much for your time. I must tellyou, I came back from your seminar soenthusiastic that the F.S.I.S. inspectorsare avoiding having any discussionsabout water activity with me. That aloneis worth the price of the seminar!”

Gary TowleTowle’s Saugany Lake Smokehouse

Is it time for yourannual calibration?

Certify your AquaLab is workingwithin specifications with Decagon’sFactory Calibration Service. The

Calibration Certificate is suitable asdocumentation for USDA and FDAcompliance of GMP and HACCP.

AquaLab Calibration Service includes:

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� Dated Certificate of Calibration.

� LoanerAquaLab tokeep youup andrunning.

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4

Dear Anthony,DDECAGON

DEVICES

0.75:1, and semi-dry sausage must have an MPR3.1:1 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 somemanufacturers may be relying upon a maximumMPR rather than water activity for determiningadequate drying. FSIS has clarified that MPR shouldnot be used to verify proper drying for shelf-stablemeat products. Instead, water activity, as measuredby laboratory procedure, should be used to verifythat proper drying has occurred to produce a shelf-stable product. Therefore, water activity replacesMPR as a measure of dryness for food safety, butyou may still have to measure MPR as part of thestandard of identity for your shelf-stable meatproduct.

I have reformulated my product andlowered the water activity to 0.86, whatis my shelf-life?I am asked this question quite often, but am sorry

to say that I cannot answer this questionwithout more information. Many foodproducts are required to have some type ofopen date, but how does one determinethis date? The first piece of informationnecessary to determine the shelf-life of afood is to define what is and what is notan acceptable product. Many times thereis an indication of product acceptabilityfrom your consumer complaint files, butmost companies tend to focus on thecharacteristics of the best product insteadof an unacceptable product.

Once you have a good feel for what the consumerconsiders as end-of-shelf-life, you need to understandthe mechanism(s) responsible for the spoilage. Thereare many pathways for food spoilage, such asmicrobial growth, chemical degradation, enzymaticreactions, and physical property changes (texture,flavor, odor, organoleptic, etc.). Many times thesespoilage pathways are occurring simultaneously. Inaddition, there are many factors such as formulation,processing, packaging, and storage conditions thathave great influence on these mechanisms ofspoilage. An understanding of the interaction

I am trying to makea shelf-stable meatproduct and amconfused by theterm moisture/protein ratios.What is it and do Ihave to measureMPR?The main objective inmaking a shelf-stablemeat product is to arriveat a combination of

hurdles that inhibits undesirable microbial growth,while supporting desirable microbes in somefermented meat products. Some important hurdlesfor meat products are: water activity, pH,temperature, redox potential, preservatives, etc.There are many combinations of hurdles that canachieve product stability. For example typicalfermented sausages have been categorizedas 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 pHranges for shelf-stable products is in the2005 Food Code definition of PotentiallyHazardous Foods Interactive Tables.

Moisture/protein ratios (MPR) arecommonly used in the U.S. to classifydried sausages and other meat products.These ratios express the percent moisturedivided by the percent protein. Although the MPRvalues do indicate the degree of product drying, theyare not correlated well to microbial safety orstability, as with aw values. Water activity is the mostimportant single factor for shelf-stability (asindicated by microbial stability) of dried meats.Regardless, the FSIS Food Standards & LabelingPolicy Book still identifies criteria for a shelf-stableproduct based on MPR. These historic MPR valuesare based on average values of a market basketsurvey that representative products exhibited at thetime of the initial classification. Shelf-stable drysausage must have an MPR 1.9:1, jerky an MPR of

5

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between these factors is key to shelf-life estimation.

Water activity has a pronounced affect on thesespoilage pathways and mechanisms through itsinfluence on microbial growth rates, chemical/biochemical stability and physical properties offoods. For example, to make a shelf-stable product,you may have lowered the water activity to 0.86 formicrobial control. But, if you lowered your product’swater activity by adding high fructose corn syrup (aninexpensive humectant and reducing sugar) and yourproduct contains free amines from proteins or aminoacids, then nonenzymatic browning will occur andyou will see a color darkening and flavor changeduring storage. On the other hand, if you loweredthe water activity using sucrose (a non-reducing

sugar) then the browning reaction willnot proceed and you would have

a much longer shelf-life.Therefore, an effort to

enhance shelf-life bychanging a singleingredient may lead tounexpected chemical orphysical changes and

require reformulation ora change in processing or

packaging to obtain thedesired shelf-life.

Information is needed on the ingredients,formulation, processing conditions, packaging, andexperimental data under abuse conditions in order toanswer your question “What is my shelf-life?”.Accelerated shelf-life testing is where finishedproduct is monitored under abuse conditions untilunacceptable. The abuse conditions are typically,higher temperature and relative humidity (or wateractivity). Decagon’s SafeStorage Monitor for in-package water activity/temperature logging is idealfor collecting this type of data. The accelerated shelf-life data is then used to project shelf-life undernormal storage conditions. Models that incorporatethe effect of temperature and water activity areexcellent for shelf-life predictions of moisture-sensitive foods. �

“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

performance of electronic devices. I

would definitely recommend your

products to other customers.”

—Terry C. Llewellyn Jr.Plant Manager

Kettle Valley Dried FruitA SunOpta Company

ExcellentWater Activity Measurement

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AquaSorp Isotherm GeneratorNew Product

the driving force for moisture migration. Knowledgeof whether water will absorb or desorb from withina load of DDGS is essential to prevent degradation.Thus, water activity is an important parameter sinceit can control water migration in mixed lots ofDDGS. Different loads of DDGS could have differentwater activities due to variation in drying conditionsand amount of added solubles. By definition, wateractivity dictates that moisture will migrate from aregion of high aw to a region of lower aw, but the rateof migration depends on many factors.

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

though their moisture contents are the same. Thismoisture migration could lead to flow or microbialgrowth problems.

ConclusionWater activity is an effective process control andquality assurance tool for maintaining the stabilityand safety of DDGS and should be included as arecommended analytical method for DDGS. Inaddition to the reasons outlined above, water activityis a more effective moisture analysis than moisturecontent because it is more sensitive and accurate. Inthe intermediate moisture region, which includesDDGS, changes in moisture content that areundetectable due to the limited accuracy of moisturecontent analyses can result in large changes in wateractivity and consequently, changes in stability. Thiscan be disconcerting when DDGS are dried to amoisture content specification and stability changessuddenly occur even though a moisture contentchange is not detected. These stability changes can bepredicted if a water activity specification is used.Water activity is a fast, inexpensive, and accurateway of assuring the quality and safety of DDGS. Itcan easily be incorporated by any ethanol plant. Ifinterested in learning more about water activitytesting and DDGS, please contact Decagon. �

Quality of Dried Distillers Grain continued from page 3

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THOUGHT QUESTION—If equalamounts of one load of DDGS at15% moisture and a second load at15% moisture content are blendedtogether, will there be moistureexchange between the loads?

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ak State Products makes cookies. Lotsof them. They make them crunchy,soft, high fat, low-fat, full of fiber, andground up as inclusions in ice creamand candy. In fact, Oak State has

made, is making, or will make cookies for nearlyevery major cookie label. They make what thecustomer wants, and that starts with formulation inDavid Busken’s lab.

From Concept to MarketBusken is Manager of Research and Development atOak State Products. They bill themselves as takingquality products “from concept to market.”“Customers come to us with a concept, and we growor refine that concept,” he says. “They tell us whatthey want—longer shelf life, a particular protein orfiber content—and we do the formulation.” Often,figuring out how to make what the customer wantsinvolves working with water activity.

Go Too High, You’ll Get MoldProducts made to be stocked on grocery store shelvesneed a shelf life of six months, and that can gettricky with a soft cookie. “Water activity is critical insoft cookies,” he says. “There’s been lots of R & Don how to keep cookies softer longer. We need to putmoisture into the product and hold it there withoutmaking the water activity too high. You have to getthe moisture in there, but if you go too high, youget mold.”

Soluble Fibers Absorb More WaterBusken says he will typically “work up a formula,

make it up in the lab, bake it off, look at the wateractivity, then hold it and see how it ages.” Some

ingredients make formulation tougher.Fibers, for example, are “notorious.Fibers, especially soluble fibers, suck up alot of water. You put enough water in toget the right viscosity of the dough, andboom! The water activity is through theroof.” Then with soft cookies, “the bake iscritical. You can bake them enough to set up, butonly water activity will tell you if you’ve baked it outenough. If the water activity is still too high, you’regoing to have to do something about it.”

Water Activity Data is RequiredWater activity measurements are not just critical inthe lab. Nearly all of Oak State’s customers demandwater activity data, and most products must meetwater activity specifications. “You can’t run withoutwater 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 knowwhere you’re at on water activity before you say‘We’re good to go.’” �

“They tell us what theywant—longer shelf life,a particular protein orfiber content—and wedo the formulation.”

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

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

Elizabeth PappasAnalytical Chemist

BEST

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History of Water ActivityMeasurementi continued from cover

put into a food to directly measure water activity.Rather, aw is measured with a technique that directlyor indirectly measures vapor pressure or someparameter relatable to vapor pressure. The methodsand instruments vary in accuracy, repeatability, speedof measurement, stability in calibration, linearity,and convenience of use.

Scott, in his pioneering studies on the relationshipbetween aw and microbial growth, used a bithermalequilibration apparatus as shown inFigure 1. The method and apparatus was originallydescribed by Stokes in 1947 and was used todetermine the water activity of saturated salts, whichare still used as reference tables today. Because Scottused this method and the saturated salt tables, it hasbeen stated that if there is such a thing as a referencemethod for aw determination it is probably thebithermal equilibration technique. Although not afast technique, it did produce accurate water activitymeasurements with good temperature control andmeasurement. Water activity was calculated from theratio of vapor pressure read from psychrometrictables at the two temperatures.

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

Another early method was the direct measurementof the vapor pressure of foods using manometry.Makower and Myers in 1943 demonstrated thistechnique for foods, but erroneously equated thevapor pressure to total moisture. A vapor pressuremanometer is shown in Figure 2. With goodtechnique and temperature control, these instrumentshave relatively high reported precision (±0.002aw).They are relatively inexpensive, but unfortunatelyare cumbersome and extremely fragile.

Figure 2. Vaporpressure manometerfrom Troller, JA &Christian JHB 1978, WaterActivity and Food, AcademicPress, NY pp13-47.

Over the years a category of wateractivity measurement techniquesbased on the moisture sorptionisotherm of either the food sampleitself or a reference material havebeen used. These methods include: isopiesticequilibration, graphical interpolation, and saltimpregnated filter paper. One of the main advantagesof these techniques is that they require veryinexpensive equipment and supplies. Only adesiccator, salt, and balance are needed. Figure 3 isan illustration of an isopiestic equilibration chamber.However, they require long equilibration times andthus are not practical for routine or quality controltesting. Over the years improvements in thesetechniques have appeared but they still require 1 to24 hours to measure water activity.

Figure 3. Isopeistic EquilibrationChamber

In the 1960s andearly 1970s,companies begandesigning anddevelopingintermediatemoisturefoods usingwater activity technology.Commercial instruments designed specifically tomeasure water activity of foods began to appear.These instruments and devices include: hair orpolymer hygrometer, freezing point depression,thermocouple psychrometry, electric hygrometer, andchilled mirror dewpoint (see sidebar for illustrationsof the instruments and sensors). These earlyinstruments were still slow to equilibrate (requiring 1to 24 hours), had limited measurement range, andwere accurate to no better than 0.02aw. Electrichygrometer sensor technology improvementsthrough the 1970 and into the 1980s reduced the

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measurement time to approximately 30minutes with a ±0.015aw accuracy. Not until 1987,

when Decagon Devices introduced the AquaLabchilled mirror dewpoint water activity meter with it’s<5 minute measure time and ±0.003aw accuracy, didmeasurement become practical for quality andprocess control.

In 2000, Near Infrared Spectroscopy (NIR) wasapplied to water activity. NIR is used to measuremoisture, fat, protein, carbohydrates, and ash inmany food products, however, aw by NIR is a newconcept. NIR water activity measurement consists ofusing a spectrometer and chemometrics software tofirst form a calibration curve for a particularproduct, and then using that calibration curve torapidly predict the water activity of further samples.Decagon has commercialized this technology andscientists at Decagon have made calibrations formany different food types with ±0.01aw accuracy.There are several potential advantages to using aNIR system: 1) Water activity measurement usingNIR is nearly instantaneous, which would vastlyreduce the time spent on product analysis. 2) TheNIR method can be applied to a wider array ofapplications, such as on-line analysis of products.3) NIR measures the water in the product not the airthat is equilibrated with the product.

With technological improvements, the timerequired for water activity measurement hasconsistently decreased. A report in the soils literatureabout 50 years ago, describing a thermocouplepsychrometer system used for measuring wateractivity, suggested an equilibrium time of a week.Early mechanical hygrometers required a day ormore for water activity measurements on foods.Decagon’s SC10A thermocouple psychrometer usedfor foods measurements about 20 years ago required20 minutes for thermal equilibrium and 1 to2 minutes measurement time per sample. It read9 samples at a time. With improvements in materialsand sensors, the AquaLab dewpoint instrument nowreads individual samples in 2 to 5 minutes and usingNIR technology, the analysis time is now 6 seconds.

What does the future hold? �

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

Michael P. PappasQuality Assurance Manager

Rich Products – Wheeling

Commercial Water Activity Instruments and Sensors

Hair hygrometerfrom Troller, JA & Christian JHB1978, Water Activity and Food,Academic Press, NY pp13-47.

Thermocouple psychrometer.

AquaLab LiteElectric hygrometer sensor.

AquaLabDewpoint sensor.

PawkitElectric hygrometer sensor.

SafeStorageElectric hygrometer sensor.

Thanks

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New Mexico Prevents Salmonellawith Water Activity Education

Jerky Producers Want Food SafetyJerky manufacturers are an especially

important group to train because ofthe risk of foodborne illnessassociated with beef jerky. A uniqueform of jerky, carne seca, is popularin New Mexico. Gerhardt workswith manufacturers to increase their

knowledge of food safety factors forjerky. “In New Mexico, beef jerky

producers must be certified by NMEDand the New Mexico Livestock Board.The Livestock Board operates inconjunction with the United StatesDepartment of Agriculture.”

Safety and Moisture-Protein-Ratio.Historically, the Livestock Board required moisture-protein-ratio (MPR) measurements rather than wateractivity to assure shelf-stability for beef jerky. When Ibegan to work with jerky sellers in 2002, some werenot familiar with the water activity requirement instate Food Regulations or the significance of wateractivity for the safety of their products. The jerkymanufacturers were not adequately educatedconcerning water activity and the Livestock Boardwas measuring MPR, not water activity.”

In 2003, beef jerky was implicated in anationwide outbreak ofsalmonella. The jerkyproducer—a New Mexicocompany—had to recall 22,000

pounds of product and live with theresulting negative publicity. JonathanGerhardt, one of five Food Specialistsat the New Mexico EnvironmentDepartment (NMED), is committed toprotecting public health and helpingNew Mexico food producers avoid similarsituations. He spends a great deal of timeeducating producers about safe foodproduction. He also trains food inspectorsto properly inspect and test food to ensureit meets state standards.

Education on Water ActivityGerhardt considers water activity measurements animportant tool in determining whether a product issafe for consumption. However, he acknowledgesthat many small producers in the industry do nothave a solid understanding of water activity. “[They]may know that 0.85 is the maximum water activityallowed in their product but they can not explain therole water activity plays to make their product shelf-stable and safe.”

HFor jerky products,what is dry enough tobe safe?

From the International Desk

The English Provender Company specializes inmanufacturing premium-quality condiments,sauces, dressings, marinades and similar

products for the retail, foodservice and foodmanufacturing markets in the UK and beyond.

Artificial colouring, flavourings and preservativesare not used, so the company has to take particularcare to ensure that its products remain stable andwill not spoil prior to use. One of the ways this isdone is by using a computer model to predictstability. However, this requires a value for theproduct’s water activity (or ERH), and The EnglishProvender Company was finding that it wasexpensive ad time-consuming to have this measured

by an external laboratory. Having purchased anAquaLab Series 3TEB from Labcell, the company’squality assurance team is now able to carry outmeasurements of water activity in-house, plus thesame instrument is being used by the productdevelopment team.

Eleven members of the quality assurance team usethe AquaLab on a regular basis to measure wateractivity. This is important for the company’semulsified mayonnaise-based products, such astartare, horseradish and seafood sauces. Furthermore as well as the tests performed on samples takenfrom the production line, ‘abuse’ tests are performed,with samples incubated at elevated temperatures forfour weeks to check that the products will not spoilif stored in non-ideal conditions.

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

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While the primary reason for purchasing the wateractivity meter was quality assurance, the AquaLab isalso playing an important role in new productdevelopment projects. By measuring water activityand using this data in a stability prediction model,the food scientists can gain a level of confidence thatnew products are safe and stable before committingto factory trials. This avoids unnecessary trials thatwould be costly and time-consuming.

Carl Steckerl, the Head of Technical at TheEnglish Provender Company, comments: “We lookedat several alternative water activity meters beforeselecting the AquaLab, and we are very pleased withit. It is easy and quick to use, it gives consistentresults, the response time is good and it isstraightforward to clean. Initially, we had some

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www.aqualab.com

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

Portable Water Activity MeterGerhardt uses a portable meter to check wateractivity during site visits. These visits give him achance to educate others about water activity.“When I am asked to accompany an inspector for anon-site visit, I see it as an opportunity to not onlycorrect operational violations but also to offerfurther training to the manufacturer.” The portablemeter gives him a chance to check water activity on-site. “As a regulator, a major benefit of having aportable meter is being able to conduct on-site wateractivity testing of products just off the productionline to ensure the product has achieved the required0.85 or less.” Gerhardt also uses the portable meterto verify water activity with manufacturers

developing products who have asked foradvice or guidance. He sees a portable

meter as a helpful tool for industry as well.“Owning a portable meter can benefit acompany in the development of a process to testthe safety and quality of the final product. It canalso 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 FoodSpecialist in the New Mexico EnvironmentDepartment to have a portable water activity meter.“New Mexico is divided into districts and ideally,there should be one meter in each district,” heexplains. “The specialists would each have their ownmeter readily available for use during a consultationor inspection.” In the meantime, the other specialistscan borrow his meter when necessary. The ability totest water activity is critical because “water activityis a scientifically proven food safety measure thatwill help protect the safety and quality of shelf-stableproducts and the consumers who purchase them.” �

DDECAGONDEVICES

queries, but Labcell arranged for some validationtrials to be carried out in the USA.”

Indeed, Carl Steckerl is very complimentary aboutthe service he has received from Labcell: “They werevery helpful when we made the initial enquiry andthen, after we decided to purchase the AquaLab,they delivered it, set it up, briefed us and carried outsome training – though very little training is needed,as it is very simple to use.”

In conclusion, Carl Steckerl says: “After threemonths, the AquaLab is proving to be just what weneeded. It is robust and reliable, and the onlyattention it requires is the weekly calibration, whichis quick and easy.” �

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Decagon Devices, Inc.2365 NE Hopkins Court

Pullman, Washington 99163 USA

1-800-755-2751509-332-2756

Fax: 509-332-5158

aqualab@decagon.com

www.decagon.com

DDECAGONDEVICES

©2007 DECAGONPRINTED IN USA

AutomaticRe-order:Your Life in the Lab Just Got Easier

Every day we get orders from anxiouscustomers who are down to their lastAquaLab sample cup or verification vial.  It

would be ideal if we could “beam” them a boxinstantly. Decagon’sAutomatic Re-order System(ARS) is the next bestthing!

Many of our customersalready participate inARS—it involves settingup a simple one-yearblanket purchase orderwith scheduled releasedates. Your ARS scheduleis flexible, so you canadjust it if your needs change. Current ARS users areenthusiastic about submitting just one PO per year.

ARS prices for sample cups and verificationstandards reflect the multiple-box discount, even ifyou only receive one box per release. Normalshipping charges and taxes (for customers in WA,IN, and SD) apply.

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

Dear Customer,

The past year has been a good one forDecagon and we hope that it has been agood one for you. We have moved intoa new building (across the street fromour old one) and made great strides in

new product development. We are proud toannounce a new instrument, AquaSorp IG (IsothermGenerator). This device will automatically create amoisture sorption isotherm, both the adsorption anddesorption curves, in about a day. Instruments havebeen commercially available previously but weretypically unaffordable for the main streamresearcher. AquaSorp is priced to make thistechnology more broadly obtainable.

We would like to thank you for your business. Ifyou have any comments or questions concerningDecagon products, please let me know personally attamsin@decagon.com.

Sincerely,

Tamsin CampbellPresident

Fundamentals of Water ActivitySeminar Schedule

West Coast:Pullman, WASeptember 27, 2007

Midwest:Chicago, ILOctober 2, 2007

East Coast:FoodsTrumbull, CTOctober 10, 2007

PharmaceuticalTrumbull, CTOctober 11, 2007

Water Activity News2007

Decagon

Seminar

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