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University of Wisconsin—Extension College of Agricultural and Life Sciences

Wisconsin Center for Dairy Research

A Technical Resource for Dairy Manufacturers Volume 19 Number 4 2007

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From photography to pharmaceuticals, maintaininghigh product quality has been a recurring refrain. It isno different in the dairy world. In the previous issue ofthe Dairy Pipeline, Bishop and Smukowski (2007)reviewed the issue of cheese safety at roomtemperature. They concluded that most cheesescontaining <50% moisture, active lactic acid startercultures, with traditional levels of salt, pH, fat, etc., do not allow thegrowth of pathogens when held at temperatures between 4 and 30ºC(39 and 86ºF). In this issue, we follow up with a discussion focused onhandling cheeses to maintain quality.

We know that cheese quality in the marketplace can deteriorate withstorage. At least that was the case back in 2003 when we reported ondefects in U.S. graded cheeses. (Smukowski et al., Dairy Pipeline 2003).We found that at four days of age, 99.4% of cheddar cheese was AGrade; at 10 days, 94.8% was A Grade; and at 30-60 days, 92.8% was AGrade. However, when we evaluated mild cheddar at retail markets, lessthan 9% of the cheese was A Grade quality. We saw similar decreasingquality in colby, jack, and swiss cheeses. This trend was alarmingbecause quality defects in natural cheeses can definitely decreaseoverall acceptance and value. Therefore, it is essential that peoplehandling cheese understand how to maintain product qualitythroughout aging, while the cheese is in the distribution and marketingchannels.

Cheese manufactureNatural cheese is a cultured product that isbiologically active throughout its life. Cheesequality starts at the very beginning, with milkquality. Milk should be produced undersanitary conditions and then cooled properly atthe farm. This limits contamination and growthof spoilage bacteria and the pyschrotrophicbacteria capable of producing heat-stableenzymes that break down protein and fat.Remember that raw milk cheeses aresusceptible to defects from the growth of anyspoilage organism that may come in with themilk supply. Thus, many cheesemakers usepasteurization or thermilization to reduce thenumber of contaminating organisms in milk,although heat treatments do not affect the heat-stable enzymes (from prior bacterial growth)that may still be present in the milk used forcheesemaking.

It is important to produce cheese under thestrictest sanitary conditions to limit theenvironmental microbial contaminants thatmay produce defects in the finished cheese. Inaddition, following proper cheesemanufacturing practices—includingcontrolling moisture and paying attention toacid development—will not only ensure thatthe template is set for good quality throughoutthe life of the cheese but will also maintain a pH

Handling Cheese to Maintain QualityBy Bill Wendorff and Marianne Smukowski

Handling Cheese to Maintain Quality ........................ 1

Research Update .............................................................. 2

News from CDR ................................................................ 6

Dairy Markets and More................................................. 8

Curd Clinic ....................................................................... 10

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Vol 19. No. 4 2007

Research Update

Although Hispanic cheeses account for only 1.6% of total US cheeseproduction, watch this market because it is growing. In fact, whiletotal cheese production increased at an average rate of 2.6% peryear, Hispanic cheese production has shown double digit increasesmost years since 1998 and increased over 75% from 2000 to 2005.The Hispanic population, at 14.8 % in 2006, is the largest minoritygroup in the United States.

If you have ever traveled far from home or lived in a differentcountry then you probably know the feeling of longing for familiartastes and smells. Americans abroad report cravings for boxedmacaroni and cheese and UK expats living in the US miss Englishchocolate bars. For me, it was six months of travel in Asia thatkindled an intense craving for pretzels. I could find all sorts ofsnack foods and they were ok, but they weren’t pretzels. When Ispied a small package of stick pretzels in a grocery store in KualaLumpur, I was excited, and really looking forward to the crunchy,salty, little morsels I would be chomping on soon. My enthusiasmturned to dismay when my taste buds detected sugar granulesinstead of the salt I expected. I was tricked and keenly disappointed.It’s possible your Hispanic cheese customers are having a similarexperience.

In the early 1900’s Italian immigrants to the United States preferredcheese from the old country, and the Hispanic population is nodifferent. According to Scott Rankin, associate professor of FoodScience at the University of Wisconsin—Madison, a large segmentof the US Hispanic cheese volume is comprised of cheeses made intheir country of origin and brought into the United States. Why isthis? One explanation could stem from complaints from Hispanicconsumers that US-made Hispanic cheeses lack “authentic” flavor.

“Authentic” Hispanic cheese flavorWhat is “authentic” Hispanic cheese flavor? Certainly, it isinfluenced by different animal feeds, milk handling, and heattreatments. And then there is the variation in milk microflora,sanitation, refrigeration and cheese composition. For example, inmany Hispanic countries, milkfat is supplemented or replaced withplant-derived oils. High levels of milk powder are another potentialflavor influence. See Figure 1. for a comparison of cheeseingredients.

A research project at the University of Wisconsin-Madison, recentlyfunded by Dairy Management Inc. (DMI), aims to answer some ofthese authenticity questions. Since 80% of Hispanics living in theUnited States emigrated from Mexico, Central America or theCaribbean the study will focus on popular cheeses from these areas.Representative samples of fresh cheese (panela and queso fresco),

Hispanic cheese and the advantage of authenticity

In the early 1900’s Italianimmigrants to the UnitedStates preferred cheese

from the old country, andthe Hispanic population is

no different.

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Figure 1. Comparing cheese ingredients

Ingredients – U.S. CheeseFreshPasteurized Whole MilkCultured Pasteurized Whole MilkSkim MilkSalt, Sea SaltRennet, EnzymesCulturesCalcium ChlorideSorbic Acid

Ingredients – Mexican CheeseFreshPasteurized Whole Cow MilkPasteurized Part-skim Cow MilkReconstituted Skim MilkMilk PowderLactic Protein ConcentrateCaseinatesCow Milk CreamButyric FatEdible FatSaltIodized SaltRennetCalcium ChlorideAdded WaterEnzymatic FlavorNatural ColorantStabilizersPotassium Sorbate

Pasta FilataMilkPasteurized Whole MilkPart SkimSkim MilkSalt, Sea SaltEnzymesCultures

Pasta FilataWhole Cow MilkPasteurized Whole Cow MilkPasteurized Part-Skim Cow MilkReconstituted Skim MilkDry Whole MilkNonfat Dry MilkCaseinatesLactic ProteinsLactic Protein ConcentrateButyric FatEdible FatVegetable FatSaltIodized SaltRennetLactic CulturesCalcium ChlorideModified StarchAdded WaterAcidifiersNatural FlavoringsNatural ColorantsAnnattoStabilizersPreservatives

continued on page 7

aged cheese (cotija, queso seco)and pasta filata cheese (oaxaca,quesillo) will be analyzed forcomposition, functional properties,microbiological analysis, non-native cheese components andsensory analysis. After comparingthe samples to US style Hispaniccheeses, the researchers hope toisolate and identify differences,with the final goal of helping UScheesemakers compete withimported cheeses.

Initial effortsInitial efforts, led by graduatestudent Luis Jimenez-Maroto andpost doc Arnoldo Lopez-Hernandez, have focused ondescriptive sensory panels, microand composition. Trained panelistshave been evaluating theappearance, texture, and flavorattributes of US-made Hispaniccheese as well as commercialsamples of correspondingSalvadorian and Mexican-madecheese. The researchers have alsoconducted focus groups with UWstudents from the Mexican StudentAssociation.

The focus group found somedifferences, shown in the photos onpage seven. For example, most ofthe US-made panela cheeses werevery salty. In addition, somesamples were oxidized and asanitizer off-flavor was found. Inother cheeses, the focus groupoften found rancid flavor notes,which is expected for cotija, but notfor oaxaca. Some shredded cheesemixtures, labeled “Mexican Blend”,contained colby, jack and cheddarcheeses, which are not Mexicancheeses!

We know that people looking forHispanic cheese begin by lookingfor a brand they know and

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level unfriendly to pathogens. The cultures, secondarymicroflora, contaminants, and enzymes present in the cheeseafter manufacture will be active throughout the life of the cheese.The impact they have on cheese quality will depend on how thecheese is handled because that influences the environmentalconditions within cheese.

Aging cheeseDuring aging, ripening of the cheese involves breakdown of thebody and development of cheese flavor. The changes are causedby the activity of cheese cultures, nonstarter lactic acid bacteria(NSLAB), and any other added ripening bacteria, yeast or molds.Contaminating microorganisms from raw milk, theenvironment, biofilms on dairy equipment, or plant personnelmay have found their way to the cheese during the cheesemaking process. Their activity in the cheese is influenced bycheese composition, temperature, pH, salt content, water activity,and amount of oxygen present in the cheese environment.Ripening activities in natural cheeses will continue to occur asthe cheese ages. Higher aging temperatures, higher moisture orwater activity, and decreased salt will promote a faster growthrate of ripening organisms and lead to a quicker breakdown ofthe body of the cheese. Higher temperatures will also stimulateincreased rates of enzyme action on cheese components andaffect the type of flavors developed during the aging process. Asthe ripening organisms grow, the environment within the cheesechanges from slightly aerobic to anaerobic. Cheese packaginginfluences the type of environment in the cheese during agingand distribution.

Distributing cheeseSince natural cheese is a biologically active product, conditionsduring transport and storage of cheese do influence microbialgrowth and enzyme activity. Temperature abuse is a commonproblem during transport; it can accelerate microbial activityand increase the potential for defects. Specific problems such asrancidity, bitterness, and fermented flavors may be exacerbatedby temperature abuse. Higher handling temperatures may causegases to expand in eyed cheeses, which can then cause splits and

cracks. Also, physical abuse during handling can contribute toproblems with splits and cracks in eyed cheeses if blocks or

pallets are dropped or bumped.

Displaying cheeseKey factors in cheese displays that affect cheese qualityare packaging, lighting, and storage temperature.Cheese packaging controls the environment of thecheese through the handling and marketing process.For example, mold ripened cheeses require aerobicconditions for proper mold growth and flavorproduction. Thus, they need to be packaged in

”

“The cultures, secondarymicroflora, contaminants,and enzymes present in

the cheese aftermanufacture will be activethroughout the life of the

cheese.

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Vol 19. No. 4 2007

continued on page 6

breathable films or perforated paperpackaging or you will see problems like

yellow-green “blue” cheese. (Johnson,2004) Also, cheeses with gas-producing

cultures, e.g., propionic bacteria orcitrate fermenting bacteria, need to

be packaged in breathable filmsto allow the release of carbon

dioxide to avoid puffy orpillowed packages

(Johnson, 2004).Warmer storage

temperatures,again, willstimulate moregas productionby fermentingbacteria, whichcause anexpansion of

gas vapors. On the other hand, lactic cultures and othernonstarter lactic acid bacteria (NSLAB) involved in ripening ofcheese tend to be facultative anaerobes and function best infilms with limited oxygen permeability and good moisturebarriers. These films are most commonly selected for packagingthe majority of natural cheeses to retard mold growth andprevent loss of moisture from commodity cheeses.

Intensity of fluorescent lighting in display cases is a criticalfactor to consider when you focus on maintaining the quality ofnatural cheeses. Lighting intensity should be held to no morethan 160-200 foot candles at the exposed surface of the cheese(Wendorff, 2006). Higher light intensities will cause pinkdiscoloration or bleaching in annatto-colored cheeses andoxidized flavors in all types of cheese (Hong et al., 1995). Heatfrom high intensity lighting can also increase the temperature ofcheese in some display cases.

Bishop and Smukowski (2007) previously reported ontemperature of cheese displays in relation to cheese safety.However, cheeses displayed at ambient temperatures in an aisledisplay will certainly lose quality quicker than cheeses displayedunder refrigeration. The higher storage temperatures dopromote faster microbial growth and enzyme activities, leadingto a faster breakdown of the body of the cheese and potentiallygenerating flavor defects that will shorten the acceptable shelflife of the cheese. This scenario is the most likely explanation forthe high percentage of cheeses at the retail market that exhibitshort, weak and pasty body defects and acid, bitter, and wheytaint flavor defects (Smukowski et al., 2003). In addition, somecheeses at higher display temperatures will sweat or lose serum

PasteurizationLouis Pasteur was the first person to demonstratethat microorganisms caused the souring of milk in1837. Around 1860 he used heat to destroyunwanted organisms in beer and wine. Althoughpasteurization of milk kills disease-producingbacteria, as well as yeast and molds, someLactobacillus and Streptococcus do survive.

Pasteurization temps and times145ºF (63ºC) for 30 minutes (low temperaturelong time, LTLT or vat pasteurization)161ºF (72ºC) for 15 seconds (high temperatureshort time, HTST)

Thermilization or heat treatmentHeating milk to 65ºC (149ºF) for 16 to 18 secondswill destroy pathogenic organisms that threatencheese safety. (Johnson et al, 1989)

PsychrotropicThis word is derived from psychros meaning coldand trephein, to nourish, and it describesorganisms that grow at temperatures between 0ºCand 7ºC (32ºF and 45ºF).

Heat stable enzymesMilk contains around 60 indigenous enzymes andmany of them survive HTST pasteurizaton. Weknow that some enzymes are active beforecheesemaking and some are active duringripening, which can affect flavor both positivelyand negatively. Somatic cells are a source ofenzymes and elevated cell numbers in milk affectthe quality and yield of cheese.

Non-starter lactic acid bacteria(NSLAB)Unlike the bacteria added to cheese to metabolizelactose to lactic acid, these are residents of theripening cheese and they contribute to flavordevelopment.

Propionic Acid Bacteria (PAB)Bacteria that produce propionic acid, important inthe transformation of lactate to propionate, acetate,and CO

2 to promote eye formation during ripening

of swiss type cheeses.

Glossary

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Vol 19. No. 4 2007

and produce calcium lactate crystals. Hard grating cheeses, withlower moisture contents, can tolerate higher displaytemperatures without developing significant defects.

ConclusionMaintaining quality in natural cheeses from the time ofmanufacture to the time of purchase is a real challenge sincenatural cheeses are a biologically active food influenced byhandling conditions. The quality template for the cheese startswith milk quality and is set at the time of manufacture. Cheesecultures and secondary microflora are regulated by cheesecomposition, temperature, pH, salt content, water activity, andamount of oxygen present in the cheese environment. However,handling procedures throughout the life of that cheese willdetermine which organisms and enzymes will react in thecheese, as well as the reaction speed and timing. The goal as acheese transporter, distributor or retailer should be to controlthose handling procedures to maintain the “window of topquality” of the cheese for as long as possible during the life ofthat cheese.

ReferencesBishop, R., and M. Smukowski. 2007. Displaying cheese safely, isthere a “right” temperature? Dairy Pipeline, Vol. 19, No. 3, Wis.Center for Dairy Research, Madison, WI.

Hong, C.M., W.L. Wendorff, and R.L. Bradley, Jr. 1995. Effects ofpackaging and lighting on pink discoloration and lipid oxidationof annatto-colored cheeses. J. Dairy Sci. 78: 1896-1902.

Johnson, E.A., Nelson, J.H., and Johnson, M. 1990.MicrobiologicalSafety of Cheese Made from Heat-treated Milk, Part. 1 ExecutiveSummary, Introduction and History. Journal of Food Protection,Vol. 53 No. 5.

Johnson, M. 2004. Uncovering the cause of cheese defects, is it theretailer, the cheesemaker or the packaging? Dairy Pipeline, Vol.16, No. 2, Wis. Center for Dairy Research, Madison, WI.

Smukowski, M., Y. Ping, W.L. Wendorff, and R.D. Rao. 2003.Cheese defects in U.S. graded cheeses. Dairy Pipeline, Vol. 15, No.2, Wis. Center for Dairy Research, Madison, WI.

Wendorff, W.L. 2006. Getting the pink out – controlling pinkdiscoloration of cheese. Dairy Pipeline, Vol. 18, No. 4, WisconsinCenter for Dairy Research, Madison, WI.

AerobicLiving or active only in the presence of oxygen

AnaerobicLiving or active in the absence of oxygen

continued from page 4

CDR 2007 Regional Workshopavailable on DVDWishing you could have attended the CDR fallregional workshops on Cheese Yield &Standardization and Cheese Health & Wellness, butjust couldn’t fit it into your schedule? Due toseveral requests, we are now offering the workshopon DVD. This three DVD set along with one CD ofall PowerPoint presentations is available from CDRfor only $30. Order yours now by emailing MargeSchobert, [email protected].

News from CDR

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Vol 19. No. 4 2007

Panela made in the U.S.

Panela made in Mexico

recognize. If nothing is availablethen they look for somethingsimilar. For Hispanic cheese thismeans the cheese should have asimple label. Also, the cheeseshould be the proper shape—which may include basket marks.In addition, Hispanic cheeses areoften fresh cheeses that have ashort shelf life, thus theexpiration date is printed in alarge font and is easy to find onthe package.

The next stepsThe researchers are compilingcompositional data on theMexican and US made cheesesand they are still collectingsamples from Costa Rica, PuertoRico and the DominicanRepublic.

Oaxaca made in Mexico

Oaxaca made in the U.S.

continued from page 3

Hispanic cheeseshould have a

simple label.

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Vol 19. No. 4 2007

Dairy Markets and Moreby Brian Gould, Ph.D., Associate Professor, Agricultural and Applied Economics University of Wisconsin—Madison

Figure 1. Class III FMMOpricing structure

You are reading an introductory column by BrianW. Gould, an Associate Professor in theDepartment of Agricultural and AppliedEconomics at the University of Wisconsin. Dairy

Markets and More, will be a regular feature in theDairy Pipeline, focusing on various aspects of U.S.and international dairy markets. Gould, whomaintains the University of Wisconsin DairyMarketing website found at http://future.aae.wisc.edu, has been affiliated with theCenter for Dairy Research since 1988 and currentlyis responsible for CDR’s Dairy Marketing andEconomics Program.

In this issue, I’d like to examine recent trends in the dry wheymarkets. Dairy farm operators, cheese manufacturers and othersin the Federal Milk Marketing Order System (FMMO), need topay attention to the monthly average NASS dry whey price. Thiswhey price has a direct impact on Class III prices via thevaluation of the Other Solids component. Figure 1 shows ageneral representation of Class III pricing under the FMMOsystem and diagrams the relationship between NASS (NationalAgricultural Statistics Service) wholesale prices and componentvalues.

Using the formula below you can reframe the relationshipbetween wholesale commodity prices and component values tothe relationship between these same prices and the Class IIIprice.

(The 2.82 factor is thecombined makeallowance associated withthe manufacture ofcheddar cheese, butterand dry whey per cwt ofthe standard milk.)

The results imply thatevery $0.01 cent increase(decrease) in the price ofwhey results in a $0.0586increase (decrease) in thevalue of Class III milk.This is important giventhe trend observed overthe last year in dry wheymarkets. Figure 2 showsthe monthly NASS DryWhey price since Federal

Order Reform in January 2000. A quick glance at the graphillustrates that, compared to the 2000-2006 average dry wheyprice of $0.237, monthly values observed in 2007 areunprecedented. What does this mean for the Class III price? Wecan do the math to see that the $0.7789 dry whey price recordedin April ’07 added $3.176 to the Class III price above the averageobtained over 2000-2006. ($0.7789 – 0.2370) x 5.86 = $3.176)

Class III price =9.64 x NASS Cheese Price + 0.42 x NASS ButterPrice + 5.86 x NASS Dry Whey Price– 2.82

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Since the high dry whey priceobserved in April, U.S. whey priceshave gone down. These lower wheyprices are due to a number offactors, including a softeningdemand in reaction to the highprices, an increasing supply of otherprotein sources (e.g., NFDM).andincreased dry whey stock. Thequestion remain: Where are pricesheaded and will they return totraditional levels? One source ofinformation you can turn to is thefutures market and recent settleprices for cash-settle dry wheycontracts. Figure 3 shows thesesettle prices at of the end ofbusiness on January 15th, 2008. Forcomparison we show the monthlyaverage Western dry whey priceobserved over 1995-2007 alongwith the top 3rd and bottom 3rd ofthe empirical monthlydistributions. Even with the droppredicted over the first half of theyear, the dry whey settle pricecontinues to be above the 13 yearmonthly averages.

With California changing themethod used to incorporate drywhey into their 4b pricing, theFMMO will be under significantpressure to also address theimplications of dry whey prices forboth dairy manufacturers and dairyfarm operators. We may addressthis in the next column.

Figure 2. NASS Monthly Dry Whey Prices

Additional SourcesJesse, E., and R. Cropp, 2004. Basic Milk Pricing Concepts for Dairy Farmers, University of Wisconsin ExtensionPublication #A3379, http://future.aae.wisc.edu/pubs/pubs/show/70

University of Wisconsin Dairy Marketing WebsiteSpreadsheet Models of FMMO Milk Pricing:http://future.aae.wisc.edu/collection/software/advanced_prices_final_version1.xlsSpreadsheet Model of California Milk Pricing System Showing Impacts of Changes in Dry Whey Assumptions:http://future.aae.wisc.edu/collection/software/California_4ab_new_12_07.xlsFlowchart of California 4a/4b Price Changes as of 12/07:http://future.aae.wisc.edu/collection/software/new_4a_4b_formulas.pdf

Figure 3. Dry Whey Cash Settles

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Curd ClinicCurd Clinic Doctor for this issue is Dean Sommer,Cheese and Food Technologist at CDR

A.

Q.

H3CH3C OH OH

Brp-cresol

natural compoundin milk

2-Bromo-p-Cresolphenolic, medicinal taint

Activated by UV light,sodium hypochlorite,or hydrogen peroxide

Bromide ionfrom salt

Figure 1. Bromination reactionAdapted from R.C. Lindsay,Wisconsin Cheese IndustryConference, Green Bay, WI 1997

This has never happened in my plant, but Ihave heard of an off-flavor in cheese described asmedicinal. Apparently, a very small amount of aparticular compound causes it; can you tell memore?

The source of the medicinal off flavor is a well-known chemical reaction that can ruin the flavorof seafood, carrots, beer, and bottled water, as wellas milk, cheese and casein. Mark Johnson says thisdefect, also referred to as phenolic taint, ordisinfectant taint, tastes like an old medicinecabinet smells. Not only is it a particularly nastytaste, it also has a very low flavor threshold, whichmeans you can taste it at very low concentrations,as low as 10 parts per trillion.

A relatively common reactionIn dairy products, the defect stems from arelatively common reaction seen when naturalcompounds in milk react with bromide ions underultraviolet light or in the presence of cleaningchemicals like hydrogen peroxide or sodiumhypochlorite, commonly known as bleach. Thisbromination reaction (see Figure 1.) producesbromophenols, the source of the medicinal taste.

This particular flavor defect tastes so bad that NewZealand researchers made a special point to thanktheir colleagues who tasted their tainted cheeseduring a research project. Mills et al weresearching for the origin of the defect in goudacheese, which seemed most pronounced in thecheese rind. Subsequent experiments

demonstrated that sodium bromide and 4-methylphenol, in thepresence of ultraviolet light or sodium hypochlorite, produced 2-bromo-4-methylphenol—the problem compound. This reactiontook place in the brine, when plant operators attempted tocontrol microflora by adding sodium hypochlorite, and thenexposing the brine to ultraviolet light.

Natural phenols are in cheeseIn a 1997 presentation at the Wisconsin Cheese IndustryConference, Dr. Robert Lindsay told attendees that the precursorcompounds for this medicinal defect, natural phenols, arepresent in cheese. In fact, they contribute to flavor notes insmoked provolone and the desirable background flavor inparmesan. (Ha and Lindsay) Although both chlorophenol andbromophenol reactions involve hypochlorite sanitizers andfollow a similar pathway the bromophenol reaction products aredetected at lower concentrations. If you want to prevent aproblem with medicinal taint then eliminate hydrogen peroxide,sodium hypochlorite and the use of UV lights in brining.

Farmstead cheesemakers can (and have) inadvertently flavoredcheese with the medicinal taint by setting forms, equipment, orcheese on a wet surface cleaned with excessive amounts ofbleach.

Over the years, scientists have suggested several other routes thatthe phenolic flavor defects have taken. For example, Wilster(Wilster 1980) notes that medicinal flavors have been found inmilk and the defect was attributed to feeding seed grainpreserved with paradichlorbenzene. He also points out thatcertain types of bacteria can produce a medicinal flavor. Back in1964, Badings et al confirmed a bacterial link by tracing thephenolic flavor in gouda cheese to natural rennet contaminatedby an unspecified Lactobacillus. Others have implicated strainsof Pseudomonas in the formation of the phenolic taint.

As mentioned earlier, phenols are naturally found in milk.However, problems can occur when more phenol is added, forexample when ointments containing phenolic disinfectants areapplied to dairy cattle, or when using water supplies containing

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Vol 19. No. 4 2007

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chlorophenols. And to complicate the picture even more, Schlegeland Babel (1963) describe their research quantifying the amountof phenol and hypochlorite needed to form a chlorophenol flavorin milk. They suggest you are more likely to see this reaction ifyou add additional phenol to the milk before the hypochlorite.When chlorine is added first it reacts with the milk and is notavailable to combine with the phenol.

Cheese plant operators need to be carefulFrom a practical standpoint, cheese plant operators need to beextremely careful when using sodium hypochlorite or UV lightsin brine systems. Operators also need to be careful whenrehydrating milk powders in water or adding any nondairyingredients, such as processing aids, even in tiny amounts. Anyingredient containing phenolic precursors, which may beproduced by contaminating bacteria such as Pseudomonas, willreact with hypochlorite ions in water to produce the strong,medicinal flavor compounds. Therefore, following best practicesindicates you should always add some milk solids to chlorinatedwater before adding any other process aids or ingredients whichcould contain phenolic precursors. This is similar to adding acup of milk to rennet dilution water to prevent rennetinactivation by hypochlorite. But, in this case, we want toinactivate the hypochlorite to prevent it from reacting withphenols and producing off flavors in cheese.

ReferencesAcero, J. L., Piriou, P. and von Gunten, U. Kinetics andMechanisms of Formation of Bromophenols During DrinkingWater Chlorination: Assessment of taste and odor development.2005. Water Research, Vol. 39 No. 10.

Adams, J. B., Lock, S. J., Toward, J.R., and Williams, B. M.Bromophenol Formation as a Potential Cause of “Disinfectant”Taint in Food. 1999. Food Chemistry. Vol. 64.

Badings, H.T., Stadhouders, J., and Van Duin, H. Phenolic Flavorin Cheese 1968. Journal of Dairy Science, Vol. 51, No.1.

Ha, J. and Lindsay, R.C., Volatile Branched-chain Fatty Acids andPhenolic Compounds in Aged Italian Cheese Flavors.1991.Journal of Food Science, Vol. 56, No 5.

Mills, O.E., Gregory, S.P., Visser, F. R., and Broome, A. J., ChemicalTaint in Rindless Gouda Cheese. 1997. J. Agric. Food Chem. Vol45, No 2.

Schlegel, J. A. and Babel, F. J. Flavors Imparted to Dairy Productsby Phenol Derivatives. 1963. J. of Dairy Science Vol. 46 No. 3.

Wilster, G. H., Practical Cheesemaking, Thirteenth Edition. 1980.Published by Oregon State University Book Stores, Inc. Corvallis,Oregon.

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Wisconsin Center for Dairy ResearchUniversity of Wisconsin-Madison1605 Linden DriveMadison, Wisconsin 53706-1565

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Technical Reviewers:Mark Johnson, CDRNorm Olson, Dept. of Food ScienceTom 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.

To subscribe to the Pipeline simplyphone, fax, or e-mail your request toCDR. (Form on page 11) We welcomeyour questions and comments. Sendthem to:

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You can also find the Dairy Pipeline onour website: www.cdr.wisc.edu

CDRJan. 24-25 Producing Safe Dairy Products. River Falls, WI. CallRanee May at (715) 425-3704 for information.

Feb. 5-6 Quality Milk Conference (WI Dairy Field Reps).Madison, WI. Call Scott Rankin at (608) 263-2008.

Feb. 26-27 Wisconsin Process Cheese Short Course. Madison, WI.Call Bill Wendorff at (608) 263-2015 or John Jaeggi at (608) 262-2264for more details.

Mar. 24-28 Wisconsin Cheese Technology Short Course, Madison,WI. Call Bill Wendorff at (608) 263-2015.

Apr. 22-24 International CheeseTechnology Exposition,Madison, WI. For information, call Judy Keller at (608) 828-4550.

May 5-8 World of Cheese—Pasture to Plate, Madison, WI. CallDean Sommer at (608) 265-6469.

May 13 Wisconsin CIP Workshop, Madison, WI. Call Bill Wendorffat (608) 263-2015.

May 14 Dairy HACCP Workshop, Madison, WI. Call MarianneSmukowski at (608) 265-6346.

May 20-21 Applied Dairy Chemistry Short Course, Madison, WI.Call Scott Rankin at (608) 263-2008.

June 3-4 Wisconsin Cheese Grading and Evaluation ShortCourse, Madison WI. Call Scott Rankin at (608) 263-2008.