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Pet Peeves put to the Test: Refrigerating Fresh Mozzarella

March 10th, 2010 · 22 Comments · Uncategorized

posted by Dave Arnold

Some things I never refrigerate:

Tomatoes –they go mealy.

Potatoes –they develop sugar and brown too much when fried.

Fresh Mozzarella –It doesn’t taste the same after it has been in the fridge. It loses its milky characteristics. I buy it the day I need it and leave it on the counter. Left- overs go in the fridge, destined for pizza or grilled cheese sandwiches.

I was recently challenged on my mozzarella habits, so I decided to settle the matter with a blind tasting. I ran two tests. The first test was my dinner Saturday night, and served as preliminary fact-finding. The second test was a more rigorous one at the FCI.

DiPalos: my favorite cheese shop.

Test One:
For the first test I purchased two identical 4.5 inch balls of fresh mozzarella from DiPalos cheese shop here in New York. Both balls were still warm and both had come from the same batch of curd, made by the same person. (DiPalos is one of my favorite shops in the whole world. Unless I’m in Italy, I won’t buy Italian cheese from anyone else.) One I left on the counter and one I put in the fridge. Three hours later the one in the fridge had only reached 11ºC (52ºF) at the core. It was taking a lot longer to chill than I had anticipated. In the interest of getting dinner on the table before my kids went to bed I cut the test short and pulled the cheese out of the fridge. The non-refrigerated cheese was 23ºC (74ºF) at the core. I didn’t have time for the refrigerated cheese to come back to room temperature so I put both cheeses in Ziploc bags and circulated them at 26.5ºC (80ºF). After an hour the non refrigerated cheese was 25ºC (77ºF) at the core and the refrigerated cheese was at 20ºC (68ºF) –still way off! Unfortunately, it was dinner time and the tasting couldn’t wait. I figured we’d taste from the outside of the cheeses –unlike the cores of the cheeses, the outsides were almost the same temperature.

How to do a blind tasting with only two people:
With a sharpie I labeled the refrigerated cheese as 1 and the counter cheese as 2, and I made sure that the holes from probing the temperatures were identical in both balls. I handed the cheese to my wife, who had no idea what the difference between 1 and 2 was, and had her unwrap the cheeses and put them on plates she randomly labeled A and B. She only knew which letter corresponded to which number, and I only knew which number corresponded to which temperature treatment. We were both tasting blind.

The First Taste Test

Results:
There was a large difference between the cheeses. The refrigerated one was decidedly less milky, and oozed far less on the plate. I liked it a lot better. My wife, however, noted that the unrefrigerated cheese had a squeaky characteristic she didn’t like. I didn’t mind it, but she was definitely right – squeakiness was a result I hadn’t expected. Because the cheeses were still not exactly the same temperature, all we had shown is that mozzarella shouldn’t be served cool. The crucial fact I learned is that it takes a long time to bring a cheese back to room temperature. My guess is that most people don’t allow enough time for cheeses to warm up. I still had to investigate the squeak phenomenon.

Squeakiness, and what’s going on in a ball of mozzarella:
I frequently visit the dairy science page at the University of Guelph, maintained by Professor Douglas Goff. I called him up. He said mozzarella was not his specialty, so he passed me to his cheese specialist colleague, Professor Arthur Hill. Dr. Hill explained several important points: The springiness of a cheese actually increases with increasing temperature. Springiness and elasticity is the result of hydrophobic reactions between casein micelles in the coagulated cheese curd. Those hydrophobic interactions are strongly temperature dependent and get stronger as the temperature increases. At the same time, however, as the temperature goes up, the milk fat provides more lubrication and the water in the system become more motile so the cheese gets softer. Cold cheese, therefore, is hard but not springy, while warm cheese is soft and elastic. Dr. Hill said that some of the original elasticity of the cheese that is lost on chilling might not be fully recovered when the cheese is brought back to room temperature. The elasticity of the unrefrigerated cheese that was actually slightly warmer than normal was perceived by my wife as squeaky.

The second question I asked Dr Hill was why the refrigerated ball didn’t taste as milky. He said that unlike most cheeses, fresh mozzarella has a lot of unbound water in it. Over time that water is reabsorbed into the protein and fat matrix that makes up the curd, and the mozzarella appears progressively drier (even if no moisture is leaving the cheese) because the water becomes bound. This is why you normally would not use today’s mozzarella to make a pizza; it has too much free water available to leak out and make your crust floppy – and it also won’t melt as well. Dr. Hill said it was possible that refrigeration enhanced water re-absorption into the cheese.
According to Louis DiPalo (of cheese shop fame), water re-absorption is why you store mozzarella that won’t to be eaten right away in liquid. The extra liquid supplies water to take the place of the water that is absorbed by the cheese. Moral: If you must keep mozzarella more than a day, make sure you store it in the liquid it was made in.

By the way, the absorption of water, which tends to make mozzarella firmer over time, is counterbalanced by protein breakdown, which tends to make it softer. That is why some liquid-stored mozzarella can actually get softer with time (but more mushy to my taste).

For more information, see these papers by mozzarella specialist Dr Paul Kindstedt at the University of Vermont’s Insititue for Artisan Cheese.

Test Two:
We purchased two 4.5 inch balls of mozzarella made at 9am from DiPalos. At 11:30AM, one was placed in our walk in refrigerator (4ºC, 39ºF), while the other was left at ambient temperature (23ºC, 73.5ºF). It took 4.5 hours for the center of the refrigerated cheese to reach (4.5ºC, 40ºF). We purchased a third 4.5 inch ball of mozzarella that had been made at 2pm by the same cheesemaker that made our 9am batch. All three cheeses were put in Ziploc bags and circulated at 23ºC (73.5ºF). It took 2.5 hours for the refrigerated cheese to get to 22ºC (71.5ºF) at the core. We tasted all three cheeses blind.

Taste Test Two

Results:
Not surprisingly, the 2pm cheese was the milkiest of all. It was too milky for one of the six tasters. The 2pm was the milkiest because it was the youngest. The two 9am cheeses were far closer in taste and texture than I thought they’d be. The refrigerated cheese was a little drier than the unrefrigerated cheese, but not by a lot. Everyone liked the flavor of the unrefrigerated cheese a little more than the refrigerated one, but the unrefrigerated cheese didn’t blow the refrigerator cheese out of the water like I thought it would.

Taste Test Two: aftermath and answers

Upshot:

Most of the damage of refrigeration can be undone by careful re-warming, but bringing cheeses back to room temperature takes a long, long time. Longer than you think and probably longer than you have time for.

You are better off never refrigerating mozzarella than serving it a little too cool.

If you’re not going to eat the mozzarella right away, store in the liquid it was made in.

For the freshest, milkiest taste, eat soon after it’s made.

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22 Comments so far ↓

  • Brian

    I love fresh milky Mozzarella, nothing compares for eating it plain.

    I wonder how a graph would look of the water content of sotred mozzarella, when is it at its driest and when does it start gaining moisture.

    Great post Dave

  • John Bailey

    OK, I walked into my friendly Costco the other day which was offering a mozzarella in a tub. This was a product from Italy and was in the refrigerated section, obviously. For those of us in fly over country, our choices are more limited, so it appreciated you gave advice on bringing product up to its best quality.

  • Andrew

    Brilliant post.
    Makes me want to go to DiPaolo’s ASAP.
    I’ve noticed over the years that lots of cheeses don’t do so well once refrigerated. Parmigiano in particular tastes much better before it is chilled. It almost has a waxy quality after that it doesn’t always lose when brought up to room temp. I wonder if Dr. Hill’s observation about elasticity not fully recovering applies to semi-soft and hard cheeses as well as mozzarella.

    • davearnold

      Andrew,
      Dunno. Maybe we have some cheese scientest lurking about who can tell us.

      • Mike Anderson

        I’ve read that freeze-thaw cycles disrupt the milkfat globule membrane in a big way – maybe the same is true for refrigeration? ‘Waxiness’ could also be the result of a warm piece of cheese leaching (‘sweating’) butterfat at room temp, which then can’t be reintegrated into the cheese structure. Great post, Dave!

  • slkinsey

    As much as I like DiPaolo, if you’re into the shaggy milkiness of truly top quality fresh mozzarella, I have to say that the mozzarella at Casa Della Mozzarella on Arthur Avenue puts anything available in Manhattan to shame. Indeed, fresh unrefrigerated mozzarella from DiPaolo is not dissimilar from “dried up a bit in the refrigerator” mozzarella from Casa Della Mozzarella. It’s a shame, really, because once I got used to the stuff from Casa Della Mozzarella (there is another pretty good maker of mozzarella on Arthur Avenue as well, but the name escapes me) I can’t go back to DiPaolo.

    Anyway, the point I’m working my way towards making is that the juicier, shaggier, milkier the fresh mozzarella is, the larger the difference refrigeration seems to make. I have found, at least with respect to the CDM mozzarella, that a brief trip to the microwave to get it up around body temperature goes a long way towards reviving the characteristics that make it so special when fresh out of the cheesemaker’s hands.

    It’s interesting that some of your tasters didn’t like the oozing fresh stuff. Now that I think about it, I’m not super-fond of a slice of oozing fresh mozzarella. When I’m going to eat fresh mozzarella as-is, I greatly prefer the golf-ball sized knots. This also gives the eater a buch better opportunity to experience the shaggy quality of the strands created by the filatura.

  • slkinsey

    Oh, and also… I wonder if the “refrigeration” phenomenon is also a function of the fact that refrigerated mozzarella is usually also quite a bit older than the 7 hours in your experiment (and thus has more reabsorption of moisture). “Overnight” is probably pretty common, because most people don’t have the stones to leave a piece of mozzarella in liquid out on their kitchen counter overnight until dinner the next day. It would be interesting to do a refrigerated-versus-unrefrigerated comparison of, say, 18- or 24-hour old mozzarella.

    • davearnold

      Howdy Slkinsey,
      I would like to do that test sometime. I like the microwave idea a lot. If you get around to doing an overnight test please let us know what happened.

  • David

    Actually it’s another example of HACCP rules going against the proper way of eating things.

    i’m sure if the inspector came and saw the Mozz on the kitchen counter he’d have a fit!

  • chadzilla

    We stumbled into DiPalo’s on our last day in NY after the ICC. Great store. Unfortunately we were flying out, and couldn’t stock up on much. Only the makings of a sandwich to scarf in the airport.
    Great post. I’ve always felt that way about refrigeration and cheeses in general. Of course, you need to refrigerate, but I like a cheese board that’s been sitting out for awhile. I don’t agree with the theory that cheese must be kept cold until it’s ready to go out to the guest. Isn’t that part of the reason cheese came about… a preservation method before refrigeration?

  • Judith Klinger

    Ciao. I live most of the year in Italy, the rest of the time I live around the corner from the school and I’m very glad to hear nobody was hurt with the liquid nitrogen mishap.
    Back to mozzarella, and a few very subjective observations and questions:
    The key to mozzarella is freshness, don’t bother spending money on imported Italian mozzarella. Buy from a good local maker, by the time the cheese takes its plane ride and goes thru customs, all flavor advantages are lost.

    I’m guessing diPaolo’s is carrying cow’s milk mozzarella. I wonder, would there be any significant difference with buffala mozzarella?
    Fiore di latte mozzarella is the runniest, how come?

    And don’t throw away the whey! It is a fantastic, nearly flavor neutral meat tenderizer.

    • davearnold

      Hi Judith,
      Dipalos makes cow’s milk mozzarella. I don’t know of anyone here in NY who gets buffalo milk curd. I heard someone explain the difference between the compositions of the two milks once but I forget what they said. Maybe some of the readers know.

      • schinderhannes

        True Mozarella is always made from buffalo milk.
        There are two DOP* grades “Denominazione d’Origine Protetta” in Italy and technically only those producers are allowed to call their product Mozarella (though everybody does). “Mozzarella di bufala campana” oder “Mozzarella di bufala”, have to be made in the Campania or Lazio areas in Italy.
        *Some Englishmen like to call it PDO for “Protected Designation of Origin”

        Since water buffalo milk is richer in fat and in milk sugar, the true Mozzarella has a unique buttery taste and everybody will prefer it in a blind tasting. (Dangerous, afterwards industrial mozzarella like dairy products will always remind you of something halfway between tofu and chewing gum.)

        Here some data on milk I gathered for the German wikipedia:

        Contents Cow Sheep Goat Waterbuffalo
        Water 87,5 % 82,7 % 86,6 % 82,8 %
        Carbohydrates 4,8 % 6,3 % 3,9 % 5,5 %
        Fat < 4,2 % 5,3 % 3,7 % 7,4 %
        Proteins 3,5 % 4,6 % 4,2 % 3,6 %

        Contents Horse Raindeer Human
        Water 90,1 % 66,9 % 87,2 %
        Carbohydrates 5,9 % 2,8 % 7,0 %
        Fat 1,5 % 16,9 % 4,0 %
        Proteins 2,1 % 16,9 % 1,5 %

        • Henrik

          I liked your article, bud sadly it’s of very limited value, since it’s based on the “Americanized” mozzarella. True Mozzarella di Bufala (available at restaurants such as Celeste on 84th St and Amsterdam Ave in NYC, which is one of the few that import their Italian groceries twice-weekly from Italy) has a totally different texture: smooth, almost fluffy with a delicious taste. You’ll never try the cow’s milk stuff again!

          • davearnold

            Dipalos also flies in Mozzarella di Buffala. It is a different product. It is always stored in whey when sold here.

          • rl

            It is so sad and infuriating when people who have no knowledge on a subject act as if they are experts. “Americanized” mozzarella? What are you talking about? Fiore di latte is not some “Americanized” version of mozzarella.
            And if you think Celeste is the ultimate in NYC offerings of anything, you have much to learn. Expand your horizons a lot before you spread more nonsense and send someone astray.
            DiPalo usually has mozzarella di bufala delivered 4 days per week, MWFSa. Just ask if it came in that day to be sure. They will not even sell it to me if it is 2nd day.
            Mozzarella di bufala is very delicate and suffers quite a bit with age. First day delivery product is still close enough to realize how superior it is to the criminal versions that are sitting around for days or weeks sold in most supermarkets and shops. They are sour for the most part and many people come to think of that as the taste of it. Acidic, etc. but that is so far from what it is when fresh.
            BuonItalia had a very good imported fiore di latte one time. Was very pricey for fiore when compared to even di bufala products, I thought. Not sure if they get it in regularly. In the back at the deli counter in a bowl of liquid, not in the front section of cheeses.

            Have not sampled Casa(or Calandra’s, probably the other place that could not be remembered above) in the Bronx but I must say that every locally made product I have tried in that area is sorely disappointing. Bread, salumi, etc. all quite mediocre. Would try it with an open mind if I have it one day.
            Obika is doing about as good a job as possible for fresh imported mozzarella or at least they were when first opened. They have a range of cow and buffalo versions to sample.
            Is mozzarella di bufala superior, overall, for straight consumption to fiore di latte, yes. But a fresh, great taste of the latter is a very good thing and better than most versions of the former that are available.

  • fanny

    this post is truly fantastic. thank you. as both a food product development manager and pastry chef, I can only appreciate this type of essays.
    x fanny

  • Jeffje

    i’ll need to dig up my lecture notes from my old food science class for the full explanation, but as i recall, the squeakiness has something to do with the way CA2+ ions interact with casein. the squeakiness goes away as the cheese ages, usually within a few hours. in Wisconsin, where fresh cheese curds are king, people love their cheese noisy. there’s also a Finnish cheese, Leipajuusto, that somehow maintains the squeakiness over several days and even when served hot and meltylicious.

  • Babette

    I’ve been making a lot of mozzarella over the past three weeks–I was getting ready to teach a class in mozz making, which I did last week, and it was a great success–everyone got the silky mozzrella I hope for them. I used a local store brand that was NOT ultra pasteurized and was getting very nice mozzarella from it.

    Today I finally got a gallon of local, slow-pasteurized milk and made mozz almost immediately. My result is so different than the other milks–and I don’t like it as much. It is much drier, although I drained less whey off during kneading–and it is squeaky WARM (before it cools down), which drives me nuts.

    I DID let it rest 5 min after the rennet, which was what the store-brand needed–should I have checked after 3 min? It’s a shame, bec. it’s lovely milk, but I don’t like this batch of mozzarella. I wanted to share it with a local food truck, but I don’t like it enough…I heated it an extra pass, which has done the trick in getting the cheese to that soft, silky stage for stretching in the past, but not this time…

    Would love to hear your comments on why this happened… I read above about squeaky cheese, but as I said, this is squeaky WARM. Overkneaded? Treated it too much like the store milk?

    It was a relatively expensive experiment (although it will make great pizza cheese this week).

    Love this whole article.

    • davearnold

      Hello Babette,
      I don’t know why that would happen. If I can remember I will float the idea past the next couple of cheese experts I talk to.

      • Babette

        Thanks, Dave. Since then, I’ve made two more batches. One with good, slow-pasteurized whole milk, in bottles and from local store–milk was from a farm about 100 miles away. It was an incredible batch, soft, melt in your mouth. I added rennet at 88 degrees, didn’t overheat and worked it very little.

        So yesterday I got very fresh milk from local farm–the same place that prompted me to write the post above. It was non-homogenized. I whisked it. I heated it slowly. I added rennet at 88 degrees..I let it rest only three minutes and worked quickly…I didn’t overwork it…and it still has a firmer (It’s good, don’t get me wrong) texture than the soft batch I loved so much. It has a very very slight squeak (nothing like last week’s)…

        Would love to hear about any thing you learn…I’m still scouring the internet for more info..

        Thanks..

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