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.
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.
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.
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.
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.
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.