Dairy Pipeline

What's Inside:

University of Wisconsin—Extension College of Agricultural and Life Sciences

Wisconsin Center for Dairy Research

A Technical Resource for Dairy Manufacturers June 2003, Volume 15 Number 2

Moisture migration in cheese ...................................... 1

Popular feta faces identity crisis .................................. 2

Curd Clinic .......................................................................... 8

Skimming the Shelf ...................................................... 10

Calendar .............................................................back page

This information won’t be completely new if you have ever taken theWisconsin Cheese Manufacturing Short Course. In addition, chemicalchanges in casein as a result of pH, temperature, proteolysis and loss ofcalcium were addressed in previous Pipeline articles. See Vol. 11, No. 2,Vol. 12, No. 1, and Vol. 14, No. 4

The water molecule is a quirky one. It is simple but complex, abundantbut not always available. So many substances dissolve in water that somepeople call it the universal solvent. Perhaps that is why most of themoisture, or water, in cheese is mobile; it can move if compelled to do so.The most obvious example is the way cheese dries when exposed to air. Itis usually done intentionally, with positive results; other times it is notwelcome. For example, moisture migration in retailpackages of shredded cheese is a commonproblem. Here’s how it happens. Moisture cancreate a humid environment when it movesfrom cheese to the surrounding air. This isaccelerated when the cheese and the air in thepackage warms, for example when bright lightsilluminate the cheese or when the air in thestore meets the package face. Inside thepackage, moisture is lost to the air. Most of themoisture comes from warm cheese in the frontof the package; meanwhile the cheese and

packaging material in the back may remaincold. When the humid air inside of the packagemeets the cold cheese it condenses. The coldcheese then absorbs the water and may becomesoft and pasty, allowing the shreds to fuse.

Another example is seen when cheese ispackaged with other foods. Moisture willmigrate from products with high moisture orwater activity, to low moisture products (oreven air) and products with lower wateractivity. So, in some cases, cheese gets softwhile other times the cheese dries out. This iswhy separating foods with different moistureand water activities is a good idea.

Packaged brined cheesesYou can also see moisture migration inpackaged brined cheeses, like mozzarella orbrick. The outside of the cheese is, of course,higher in salt. The high salt attracts moisturefrom the lower salt areas in the interior of thecheese. Depending upon the moisture content(and fat) the outer portion of the cheese maybecome pasty and mushy, conditions that makeshredding or slicing difficult.

The migration of cheese serum—the waterand anything dissolved in it—can result inmoisture and pH gradients within a block ofcheese. These gradients lead to variation in thephysical characteristics of the cheese,influencing color, shred and meltcharacteristics and even eye development inSwiss. Some parts of a block of cheese maybecome too soft and pasty—which presentschallenges when taking samples that arerepresent the entire block of cheese. Also,

Moisture migration in cheese—gauging theeffects of moisture loss and moisture gainBy Mark Johnson, senior scientist, Wisconsin Center for Dairy Research

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Popular feta faces identity crisis

continued on page 4

If you are like most Americans you probably first encountered fetacheese adorning the Kalamata olives, fresh tomatoes, red onion andlettuce of a Greek salad. In recent years the popularity of feta cheesehas grown tremendously, here in Wisconsin the production of fetacheese jumped 20% from 2001 to 2002. In many regions of thecountry you can start your day with a spinach and feta omelet andmove on to feta stuffed savory pastries, portabella mushroom andfeta sandwiches or tuna and feta tacos. And, of course, any saladcan be topped with crumbled feta cheese.

In fact, in western Europe what we call a Greek salad might becalled a Macedonian salad, and to get the same meal inBulgaria you would ask for a Russian salad. We all know whatit is, does it really matter what we call it? As it turns out, in thecase of feta cheese, it might matter—a lot.

The latest round of the feta food fight started in October 2002when the European Commission granted feta cheese thespecial status of a Protected Designation of Origin or PDO.This means that Greek feta is the equivalent of FrenchRoquefort; feta can only be made from sheep or goat’s milk inGreece. It is interesting that most PDO’s are awarded for aspecific region of a country, linking a product to localinfluences. However, under this ruling, the whole of Greececan produce feta even though soil, rainfall, and climate varygreatly.

Denmark, Germany, Italy and France currently make fetacheese, but Greece claimed the PDO status for feta based on historyand tradition. Although the majority of the world’s feta cheese isproduced outside of Greece, the Greeks have been producing fetafrom ewe’s milk, or a mix of ewe and goat milk, for thousands ofyears. They claim feta as their own and insist that the historicalrecord supports Greek origins for feta. However, according to cookand author Clifford Wright, the word feta doesn’t exist in classicalGreek. He claims it originates from a New Greek word, tyripheta,which means cheese slice. The origin of this word is the Italian fette,or slice of food. Others suggest that feta cheese originated on theBalkan peninsula, which is now southern Bulgaria. Macedonia hasalso been tabbed as the birthplace of feta.

It is unlikely that anyone can conclusively track down the origin offeta, and that isn’t really the question here anyway. Another way toframe the issue is to ask: Is feta a generic term for tangy, square,brined white cheese or is it a word that specifically applies to cheesemade from ewe or goat milk in Greece, according to the Greek rulesof production that date back to 1936? For most Americans, whoonly know feta as a salty cheese made from cow’s milk, the answer

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Paris Convention for the Protection of Industrial Property,1883Art. 1 includes indications of source and appellations of originamong industrial property, protected by the Convention;♦ protection of geographical indications against falseindications of source;♦ protection of geographic indications depends on the law ofthe country providing protection.

Madrid Agreement for the Repression of False or DeceptiveIndications of Source of Goods, 1891♦ Extension of the protection of geographic indications againstfalse or misleading indications of source;♦ Protection depends, as in the case of the Paris Convention, onthe law of the country providing protection i. e. this countrydecides whether a geographical indication constitutes anindication of source or whether it is a generic name. (exceptionfor geographical wine designations: country of origin).

Lisbon Agreement for the Protection of Appellations ofOrigin and their International Registration, 1958♦ Adoption of the French definition of appellation of origin, i. e.protection merely for indications, where the quality andcharacteristics of a product are due exclusively or essentially tothe geographical environment, including natural and humanfactors;♦ Protection merely for appellations of origin that arerecognized and protected as such in the country of origin(Agreement presupposes a national system of protection andregistration);♦ Establishment of an international system of registration andprotection.

Stresa Convention for the Use of Appellations of Origin andDenominations of Cheeses, 1951♦ Protection of “appellations of origin” and “denominations ofcheeses,”♦ Appellations of origin which are the object of internallegislation reserving their use, within the territorial confines ofone of the Contracting Parties, to cheese manufactured ormatured in traditional regions, by virtue of local, loyal anduninterrupted usages, are listed in Annex A (protection of theorigin);♦ Denominations of cheeses that are the object of internallegislation within the territorial confines of the ContractingParty, which first has used these denominations and which usesthem only for cheeses having definite characteristics, arespecified in Annex B (protection of characteristics);♦ Inclusions in Annex A require a majority of three quarters of

History of International developmentsFrom Joerg W. Rieke (J.D.), German Dairy Association (MIV), Bonn/GermanyPresented at the Wisconsin Cheese Industry Conference, April 15-16, 2003 LaCrosse, WI

all members, those in Annex B require a simplemajority♦ Denominations of cheeses enlisted in Annex Bshall not be transferred to Annex A; they may beused by the other Contracting Parties for cheeseshaving the characteristics defined in Annex B,provided that the denomination is accompanied bythe indication of the manufacturing country.

Annex APecorino Romano (Italy)Parmigiano Reggiano (Italy)Gorgonzola (Italy)Roquefort (France)

Annex BHavarti (Denmark)Samsoe (Denmark)Gruyere (Switzerland/France)Emmental (Switzerland)Edam (Netherlands)Gouda (Netherlands)Caciocavallo (Italy)Provolone (Italy)Asiago (Italy)Fontina (Italy)Saint-Paulin (France)Brie (France)Camembert (France)

WTO Agreement on Trade-Related Aspects ofIntellectual Property Rights (TRIPS), 1994Competing positions in the Uruguay Round of theGATT: EU proposed a “French-style“ protectionsystem; USA favored the protection of geographicindications through a certification mark systemThe result: Section 3 of the TRIPS Agreementcovers six topics:♦ Definition and scope of a geographicalindication♦ Minimum standards and common protectionprovided for geographical indicationscorresponding to all kinds of products♦ The interrationship between trademarks andindications of origin♦ Additional protection for geographicalindications for wines and spirits♦ Negotations and review♦ Exceptions to the protection of geographicalindications

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seems obvious—it’s a generic word. For Europeans, who haveeaten sheep’s milk feta as well as feta made from cow’s milk fordecades, the issue might be murkier.

Joerg Rieke, German Dairy Association, traveled to the WisconsinCheese Industry Conference in April, 2003 to participate in apanel discussion of global trade issues. He focused on theEuropean perspective regarding PDO issues— of which feta isonly one component. (See sidebar for his summation ofinternational developments.) Rieke notes that although theEuropean Commission’s ruling on feta doesn’t affect Wisconsincheesemakers, we need to pay attention to ongoing discussions ofthe World Trade Organization. Currently, the WTO Trade-RelatedAspects of Intellectual Property Rights, or TRIPS, agreementprotects geographic indicators that identify wine and spirits.Some WTO members want to extend protection of geographicalindicators to many other goods, and that list contains cheeses weare very familiar with—Emmental (or “Swiss”), Asiago,Parmesan, Muenster, etc.

Under the TRIPS agreement, geographical indicators (GI’s) fallunder the rubric of intellectual property. The official definition ofa GI, from Article 22.1, includes the concept that “... indicationswhich identify a good as originating in the territory of a Member,or a region or locality in that territory, where a given quality,reputation or other characteristics of the good is essentiallyattributable to its geographic origin.” Thus, the link (it doesn’thave to be a geographical name) between the good and theregion producing it is protected.

As Rusty Bishop, Director of Wisconsin CDR and chair of the U.S.National Committee of the International Dairy Federation, notedin a recent publication, U.S. dairy representatives view the fetaissue, and others like it, “as an attempt to create new tradebarriers.” However, any legal disputes among WTO membersregarding the geographical indicators behind PDO’s would fallunder intellectual property rights disputes heard by the WTO, nottrade barrier cases.

Regarding the feta issue in the EU, Denmark filed a lawsuitagainst the European Union’s executive commission

December 2002 in an attempt to overturn the ruling. Totrack this issue, or other PDO issues involvingParmesan, Emmental, etc., and to gauge how it willaffect U.S. cheesemakers, you should pay attention toupcoming WTO formal talks in September, 2003 at aministerial meeting in Cancun, Mexico. Better yet, youcan get involved through the U.S. National Committee

(USNAC) of the International Dairy Federation (IDF).Contact Deb Wendorf-Boyke at 608-663-1250 ext 112 or

usnacsec@usnac.org

U.S. dairy representativesview the feta issue, andothers like it, “as anattempt to create newtrade barriers.”

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News from CDRAttention Wisconsin cheese makersinterested in Italian cheese!Jim Path is organizing an artisan cheese making course that willfeature “Cheese Masterpieces from Italy.” If you are in the MasterCheesemaker program the full two day course is required. Thefirst day, which is mainly lectures, is recommended for cheesemakers returning for additional cheese certification since it willfulfill a Master’s requirement.

Discussion topics on the first day will include an overview of theItalian dairy industry, including different styles of freshmozzarella, manufacture of Gorgonzola, Asiago, and Grana, aswell as tasting and evaluation of select Italian cheeses.Participants will be busy making cheese on the second day ofthis seminar. Enrollment is limited, sign up early. Any questions?Contact Jim Path at (608) 262-2253 about the curriculum, andCALS Outreach Services about registration, (608) 263-1672.

CDR welcomes another talented cheesemakerBrian Leitzke, formerly of White Clover Dairy, has joined CDR’scheese program. Brian has been a licensed Wisconsincheesemaker since 1996. Though he has experience makingEdam, Gouda, Havarti, and reduced fat cheese, Brian says heenjoys making just about any kind of cheese .

WMMB brings Gordon Food Service andcustomers to WisconsinCDR spent an entire day talking about cheese with several dozen

pizzeria and Italianrestaurant ownersfrom the upperMidwest. This visit—one of the WisconsinMilk MarketingBoard efforts toincrease the use ofWisconsin cheese—involved teachingand talking with therestauranteurs, allcustomers of GordonFood Service of

Big Dave twirls a pizza crust

Michigan. They learned about the melt, stretch, and spread ofcheese, alternative cheese blends, and applications for cheese usethat got them thinking beyond pizza. And, if that wasn’t enough,Big Dave and Pizza Paul came by and put together a stunningarray of pizza varieties.

Mark Johnson compares pizza cheeses.

WMMB kept these customers of Gordon Food Service busy during their Wisconsin trip. They saw the whole cycle of thedairy industry, starting with a few Wisconsin dairy farms, visited some cheese plants and spending the day with CDR.

Restaurant owners assess stretch and melt

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smaller retail packages will vary in compositionwhich in turn will affect the accuracy ofnutritional information.

Serum can move in response to temperature; itmoves from warm to cooler areas during thecooling of freshly manufactured cheese. Pressureinfluences migration, and, in the case of airdrying, serum moves from areas of high moistureto areas of low moisture.

Whether moisture moves in response to thesefactors —and how fast it moves —depends onthe ability of the casein or casein network incheese to hold or restrict the flow of moisture.Also, the physical condition of the curds,particularly how fast they fuse or knit, can slowmoisture movement. Other factors that must beconsidered, especially in the initial stages ofcooling the pressed cheese, are cheesecomposition, pH and salt content. These factorsinfluence moisture migration by affecting theability of the casein network to hold serum. Inaddition, changes in the casein network as theresult of proteolysis, and pH changes during theripening of the cheese, will greatly affect theability of the casein to hold moisture and slowmoisture migration. Proteolysis in low salt cheeseswill increase the ability to hold moisture whileproteolysis in high salt cheeses produces freemoisture. However, if the pH increases in a cheesewith an initial low pH, such as Camembert, freemoisture will be absorbed by the casein.

Syneresis and the creation of freemoistureCasein micelles are bundles of hundreds of caseinmolecules and they are full of “free” moisture.During cheesemaking, while milk is clotting, thecasein micelles aggregate into clusters. Theseclusters aggregate into larger clusters, eventuallyresulting in clotted milk, which you can think of asa casein network. In the process, pools of moistureand fat are trapped between and within theclusters. As soon as the clotted milk is cut, thecaseins begin to tighten and, in a process calledsyneresis, moisture is forced from the caseinnetwork of each curd particle. When serum isoutside the curd it is called whey, but it is oftencalled free serum if it is still trapped within thecurd particle.

Both heating the curd and a continued drop in pH will acceleratesyneresis. Typically, the cheese maker helps force out the freeserum from the curd by physically pressing the curds. However,not all the free moisture within a curd particle or between curdparticles is pressed out, some is trapped. Nor is the process ofsyneresis finished. As long as the cheese is warm, free moisturewill be forced out of the casein network and then it can move.Consequently, there will be pools of free moisture remaining inthe cheese after pressing. Whether or not this moisture isabsorbed by the casein network, or moves in response totemperature, depends on the chemistry of the casein networkand the curd temperature since casein loses water when it iswarm and pools of serum form between curd particles. Caseinthat is low in calcium will absorb serum when the cheese iscooled, greatly slowing its migration. Also, curd low in calciumwill fuse better which then helps to restrict moisture movementin response to temperature.

Two events to slow moisture migrationTwo events must simultaneously occur to slow moisturemigration in cheese. The first event is to stop, or greatly slow,syneresis to prevent more free moisture from being created. Youcan do this by decreasing the temperature. Acid developmentenhances syneresis. It is more difficult to slow acid developmentwhen mesophiles are used since these cultures still produce acidat 70º F. Thermophiles can be greatly restricted by salt (less than3% S/M) and temperature (less than 90º F).

The second event you need to orchestrate in order to slowmoisture migration is to create conditions that will allow thecasein network to hold the moisture. The most common methodis to cool the curd. Although cold cheese absorbs serum, it doesnot necessarily hold it very tightly. For example, a high pH, andhigh salt cheese such as Queso Fresco will hold water whencold (40º F) (although you can see some freemoisture if you break the cheese open evenat that temperature). However, if youwarm the cheese to 50º F, a lot ofmoisture will come out of thecheese. You can see this whenyou carry around a bag ofcheese curds on a warm day,as the temperature increasesso does the moisture in thebag.

A similar observation willoccur with a cheese with verylow pH (4.9 or below). In bothcases the casein network canabsorb, but not hold the moisture,after a slight increase in temperature. A

continued from page 1Migration

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temperature, by the way, that is lower than the temperature ofmost cheese when pressed. In other words, even though thecheese is cold, the casein network does not have a strong hold onthe moisture. Cold cheese absorbs moisture becausehydrophobic interactions between casein molecules weaken. Asa result, the casein network “swells” with serum. This is easilyreversed if the cheese warms slightly, especially if the cheese ishigh in salt and there is a lot of calcium bound to the casein. Ifcalcium is lost from the casein the casein molecules will hold themoisture more tightly, restricting the loss of moisture when thecheese is warmed slightly.

Calcium removed by acid developmentCalcium is removed from the casein by acid development and bycurd rinsing. Rinsing creates an environment where themoisture surrounding the curd is low in calcium; thereforecalcium leaches from the casein. A particularly effective methodto remove calcium from the casein is to lower the pH prior tocoagulant addition since a high pH at coagulant addition leavescasein with more bound calcium.

More calcium is removed from the casein when the milk is stillliquid vs. from the curd after whey separation. The lower the pHat which most of the whey or serum is pushed out of the curd i.e.cutting pH is also effective. A lower pH at drain but a high pH atcoagulant addition or cutting is not as effective at removingcalcium from the casein. However a lower pH at rennet additionand at drain also removes the main buffer, inorganic phosphate,from the casein (see rise and fall of pH article). This could resultin an excessively low pH in the finished cheese. Consequently,when milk is clotted, or when the whey is separated at a low pH,most cheese makers will rinse the curd to remove some of thelactose—thus preventing too much acid development. Keep inmind that the higher the casein content of the milk or cheese,the lower the pH needed to remove the amount of calcium

necessary to allow the casein network to hold themoisture.

Moisture migration in large blocksMoisture migration doesn’t always occur in

large blocks of cheese, but when it doesit can be a problem. One effectivesolution involves cooling the curdprior to pressing. In Cheddar, you cando this by rapidly moving air duringvacuum transport of curd from thecheese vat to the pressing form orhoop. In washed cheeses, such asColby or reduced-fat cheeses, thecold water lowers the curdtemperature, However, even if thecurd is cool, moisture will stillmigrate if the casein network can

not hold the moisture and if the temperature of thecheese on the outside of the block is cooler thanthe inside. The cheese maker must coordinatecooling the pressed blocks with the loss of calciumfrom the casein network, curd fusion, and theinhibition of syneresis.

Cooling the curd prior to pressing can effectivelyrestrict moisture movement, but, just like coolingblocks of cheese, it must be done in unison withother events. Syneresis—curd contraction andrelease of moisture—must be slowed or stopped.Syneresis is enhanced as calcium is lost from thecurd during pressing. However, if sufficientcalcium is lost from the curd prior to pressing,syneresis will lessen during pressing. In addition,loss of calcium promotes curd fusion duringpressing. Allowing curds to fuse will help slowmoisture migration, although this may require alonger press time depending on the curd firmnessand calcium content of the casein. Longer presstimes allow for acid development by the starter tobe completed, calcium to be lost from the caseinand fusion to occur.

Certain conditions must be metIn summary, certain conditions must be met formoisture to migrate in cheese in response totemperature gradients. First, free moisture must becreated. Second, a driving force must be present tomove it, like a temperature difference between theoutside and inside of the cheese. Third, the caseinnetwork must be unable to hold the moisture. Ifyou want to restrict moisture migration inresponse to temperature then the casein networkmust be able to both absorb and hold the moisture.Both cooling, and the loss of calcium from casein,can help you do this.

Moisture migrationdoesn’t always occur inlarge blocks of cheese,but when it does it canbe a problem.”

“

The Journal of the AOAC International, Vol. 84, No. 2published a collection of papers edited by Bob Bradley andentitled “Cheese Moisture: Its Variations and measurement.CDR has a limited number of these reprints available, callMarge Schobert at (608) 262-5970 and request a copy of theBradley papers.

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Curd ClinicCurd Clinic doctor is Virginia Deibel, Ph.D. and CEO of BrainWave Technologies, Inc., Madison, WI

Q.

A.

There seems to be some controversyregarding the use of metal detectors in dairyplants. Are they necessary? How do they fit in aHACCP plan?

Not all dairy plants incorporate metaldetection into their food safety plans. However, forthose that do, metal detection should be part of theprerequisite program rather than the HACCP plan.Components necessary for a metal detectionprogram include the following:

Standard operating procedures (SOP)The metal detection SOP should include its care,use and operation. Further, SOP’s should includethe frequency of calibration (many perform thistask hourly), the types of metal wands used incalibration (ferrous, non-ferrous and stainless),and their sizes. Also, activities performed whenthere is metal found in the product, when themetal detector or its calibration fail should benoted. These activities are called corrective actions.Outlining corrective actions to perform whensystems fail is an essential part of all food safetyprograms. Events that provoke corrective actionsinclude calibration or equipment failure and metalfound in the product. Since many plants only haveone metal detector, steps outlining what to do withproducts when the metal detector fails arenecessary. Often, placing the product on hold untilthe problem is solved, then passing the productthrough the metal detector is the corrective actionoutlined.

Instances where metal detection is not possibleshould be noted on the SOP. For example, ifproducts that are too large to fit through theopening or when metallic foil is used onpackaging.

Employee educationAll employees who work with the metal detectorshould learn how use it, maintain it and performcorrective actions. Documentation of training isnecessary and should include the date, materialcovered, instructor’s and employees signature.Employee education may start with reading theSOP, hands-on instruction followed by consistentmanagement oversight.

Documentation of activitiesDocumentation is critical because it proves company policieswere performed as stated in the SOP. Documentation includesmetal detection calibration and/or corrective actions. Also, theemployee performing each activity should initial thedocumentation sheet. For calibration, record the types of metalused, sizes, date, time and any problems encountered. Whenhandling corrective actions, record the date of the problem,employee who discovered/solved the problem and action taken(i.e. manufacture called, quality control and managementnotified, product placed on hold until problem fixed and productrerun through detector). Make sure you include a place for amanager’s signature and date to signify that the management hasreviewed the document on a daily, weekly or monthly basis onthe documentation form.

It is up to each plant to choose the options that work the best forthem. The important actions are documentation of events andemployee education relating to company policies. Managementoversight should be constant to assure compliance—just as it iswith any activity.

Metal detector factsThe sensitivity is determined by the size of the opening thatproduct passes through, the type of metal present and theinherent properties of the product.

In general, the smaller the opening that product passes through,the more sensitive the detection. Therefore, select one with thesmallest opening that your products will fit through. Because thesensitivity is reduced with larger products, metal detection is aseffective. Prior to purchasing any metal detector, testing todetermine if its efficacy justifies the cost is important. Also, anymetal contaminant located closest to the opening sides willgenerate a stronger signal than metal located in the middle of alarge block. Taken together, metal detection for larger products isless effective.

Types of metal and their sensitivitiesFerrous: any metal that can easily be attracted to a magnet (steel,iron). This is typically the easiest metal to detect.

Non-ferrous: highly conductive, non-magnetic metals (copper,aluminum, brass). In dairy products, the sphere size needed fordetection is 50% greater than with other products due to theconductivity of these products.

Non-magnetic stainless steel (300 series): metals with poorelectrical conductive qualities and low magnetic permeability

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make these the most difficult to detect. When passing a dairyproduct through a metal detector, the stainless steel contaminanthas to be 200 to 300% larger than a piece of ferrous metal toproduce the same metal detector signal strength.

Shape and orientationThe metal contained within calibration wands is usuallyspherical because the shape is equal from any dimension. Thiswill produce an even signal from anywhere within the opening.Non-spherical metals do not produce uniform detection signals;which decreases the detection capabilities of the machine. Metalsdetected in dairy settings rarely are spherical in nature. Forexample, a wire from a cutting harp may produce a signal nobigger than the diameter of the wire, which is under thedetection limit.

Package positioningWhen detecting 300 series stainless steel contamination, thepositioning of the product through the metal detector becomesimportant. The signal is strongest if a package enters the openingat an angle or on its end. When the package enters the openinglying down and not angled, a weaker signal is generated.Positioning for the detection of ferrous metals is opposite that ofstainless steel; ferrous metals produce strong signals if thepackage enters the opening straight and lying down and a weaksignal if the product enters the opening on an angle in a standingposition. In dairy settings, 300 series stainless will be the sourceof most metal contamination. Therefore, products placed flat on aconveyer belt will create a weaker signal.

Inherent properties of the productMetal detectors work by reading magnetic characteristics orelectrical conductivity. Dairy products have high moisture, fat,acidity and contain salt; these properties are electricallyconductive. Since metal detectors must be programmed to readabove the natural product electrical conductivity, the baseline ofthese products needs to be higher thus smaller metal pieces maynot be detected.

Should metal detectors be a CCP?During a hazard analysis, if plants have raw ingredients or a stepin the production process that produces a reasonably likely riskfor metal contamination, then metal detection should beconsidered as a CCP. However, it is generally accepted that mostraw ingredients or processing steps in dairies do not create ametal hazard. While there may be occasional instances of metalcontamination, it is not a consistent occurrence. CCP’s are put inplace to mitigate significant hazards that are reasonably likely tooccur on a consistent basis. (For example, pathogens are oftenfound in raw milk. Pasteurization is a CCP). Additionally, if metaldetection is a CCP, all products produced must pass through ametal detector. When metal detectors malfunction and there isno spare, all products must be placed on hold until the problemis resolved. Once resolved, products can be released from hold as

they are passed through the metal detector. Metaldetection in dairy products is often inconsistentdue to the inherent properties of both the productand the metal detector capabilities. Therefore, inmost dairy settings, it is commonly accepted thatmetal detection is not a CCP.

Is metal detection required?Are metal detectors necessary if metal detection isnot a CCP? Bolts, wires, tools or other metalhazards occasionally find their way into dairyproducts during production. It is up to the dairyplant to determine whether a metal detector isneeded. Customers of most cheese producerseither currently or in the near future will requiremetal detection as a condition of product sale.Metal going through grinders, slicers or augers cancause significant damage. If a cheese product is notprocessed further but only rewrapped, at somestage of the manufacturing process, metaldetection should occur as a means to reducephysical hazard contamination risk. Theresponsibility then falls to the dairy producer. Icecream and cream cheese producers currently arenot subjected to the same strict customerdemands. The products are not often reprocessedand as a result, the requirement is less stringent. Ifthe plant has a history of metal contaminationthen the purchase of a metal detector beconsidered.

The potential for metal contamination increaseswhen cheese is sliced or shredded. For this reasonmetal detectors are usually part of the prerequisiteprogram for a cut and wrap operation.

The decision toincorporate metaldetection is up to eachplant and should bebased on historicaldata and customerpreferences. Metaldetection in dairyproducts is not yet a fail-safe technology.

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Skimming the Shelf—

What’s New in Print?

CheeseBy Willem ElsschotIt isn’t easy to find a novel about cheese—buthere’s one for your summer reading pleasure. Thisbook has been described as a comic classic in theSeattle Times, a slightly dated tragicomedy by JulieHatfield in the Boston Globe, and lauded as a“surprisingly humane farce of ambition gonehaywire and Edam gone bad” by Mary ElizabethWilliams in the New York Times. Originallypublished as “Kaas” in the Netherlands in 1933,Cheese is the story of a lowly shipping clerk FransLaarmans, who yearns for status and respect. Theroad to success involves 20 tons of Edam, whichLaarmans plans to sell by hiring salesmen.Laarmans himself, who is so self conscious he canbarely talk to strangers, is far too busy outfittinghis new office and designing his businessletterhead.

As Laarmans prepares for his new career he stopsoutside a cheese shop, admiring the windowdisplay. The author describes it this way:

“Huge Gruyeres as big as millstones served as abase, and on top of them were Cheshires,Goudas, Edams, and numerous varieties ofcheese that were entirely unknown to me, someof the largest with bellies slit open and innardsexposed. The Roqueforts and Gorgonzolaslewdly flaunted their mould, and a squadron ofCamemberts let their pus ooze out freely. Anodor of decay wafted from the shop, but thisdecreased after I had stood there for a while. Ididn’t want to give way to the stink, and wouldonly leave when I thought the time had come.A businessman must be as tough as a polarexplorer.”

From the beginning of this story you can guess how it will end,but that is no reason to stop reading. Author Elsschot managesto evoke a range of emotions in his readers, you’ll laugh andblush and squirm in your chair as Laarman’s cheese fantasyspirals into a cheese nightmare

Elsschot’s real name was Alfons de Ridder. He worked inadvertising by day and wrote his novels at night. “Cheese” is aclassic in the Netherlands and now it is available in English.(I ordered it throught the internet.)

The Roqueforts andGorgonzolas lewdlyflaunted their mould, anda squadron ofCamemberts let their pusooze out freely.”

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Research update

It’s no secret that exercise increases the need for protein. Manypeople in the dairy industry realize that the nutritional quality ofwhey protein concentrate makes it an ideal protein supplementfor athletes. Many athletes apparently realize this too; theirappetite for sports beverages, sports bars, and supplementscontaining whey protein seems unquenchable. Supplements areparticularly popular with body builders who are aiming forstrength and bulk. But do they work?

Researchers from Victoria University in Australia reported to thescientists attending the 2003 Experimental Biology Meeting thata combination of whey protein and creatine does indeed increasestrength and produce greater muscle fiber growth. A team ofscientists lead by Mick Carey and Alan Hayes used a double blindprotocol on thirty-three subjects to compare supplements. Theexperimental subjects, who had already been using resistancetraining, were given creatine/carbohydrate (CrCHO), wheyisolate (W), creatine/whey isolate Cr/W), or a carbohydrate(CHO). All of them were matched for strength, consumed 1.5gms of supplement per kg of body weight, and took part in thesame supervised resistance program. Muscle biopsies were usedto assess changes in muscle fiber.

The Cr/W group, given the combination supplement of creatineand whey isolate, showed the greatest gain in strength, whichalso correlated with an increase in muscle fiber. In fact, thisgroup had 12 times the muscle fiber increase compared to thecarbohydrate group. Whey isolate alone, and the CrCHO group,also showed increases, but not as striking as the creatine/wheygroup.

Supplements are the whey to go

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The Dairy PipelineCenter for Dairy Research1605 Linden Dr.Madison, WI 53706-1565phone: 608/262-5970fax: 608/262-1578

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Technical Reviewers:Mark Johnson, CDRNorm Olson, Dept. of Food ScienceJim Path, CDRMarianne Smukowski, CDRTom Szalkucki, CDRKaren Smith, CDRBill Wendorff, Dept. of Food Science

The Dairy Pipeline is published by theCenter for Dairy Research and funded bythe Wisconsin Milk Marketing Board.

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CDR July 12-16 IFT Annual Meeting, Chicago, IL. For information seewww.am-fe.ift.org.

July 31-Aug. 3 American Cheese Society Annual Meeting. SanFrancisco, CA. For info, call (502) 583-3783.

Aug. 19-20 Milk Pasteurization and Process Control School.Madison, WI. Call Scott Rankin at (608) 263-2008 for information, orthe CALS Outreach Services (608) 263-1672 to register.

Sept. 17-18 Dairy, Food and Environmental Health Symposium.cosponsored by Wisconsin Association of Food Protection, WIAssociation of Dairy Plant Field Reps, and WI Environmental HealthAssn., Fond du Lac, WI. For more information, check the WAFPwebsite at www.wafp-wi.org.

Sept. 23-24 Italian Cheeses Artisan Course, Madison, WI. ProgramCoordinator: Jim Path, (608) 262-2253.

Oct. 7-8 North Central Cheese Industries Assn. Annual Convention.Minnesota. For information, call Dr. David Henning at (605) 688-5477.

Oct. 13-17 Wisconsin Cheese Technology Short Course. Madison, WI.Call Bill Wendorff at (608) 263-2015.

Oct. 21-22 Whey & Whey Utilization Course. Madison, WI. ProgramCoordinators: Bill Wendorff (608) 263-2015 and K.J. Burrington(608) 265-9297.