2/25/2010

Strawberry Basil Ice Cream: No More Curdling


Ah, curdling. The bane of my ice cream making existence. I can't count how many custards have been sadly ruined after several minutes of infusing, carefully tasting and adjusting, tempering, slowly heating/stirring, and then... #^$*! One second too many turns perfectly smooth, thickened custard into egg drop soup. This is probably a testament to my somewhat reckless attitude towards cooking, as I'm sure this rarely happens to other ice cream making people. Or at least, multiple times.

Sure, people say you can "save" a custard by blending it back into shape, which I did once to some ginger ice cream (it was a holiday emergency), but it doesn't come out as good as it could be. So what's the idea behind curdling anyway? And how can we prevent curdling of any custard?

The Inquisitive Cook (Accidental Scientist) states that "In both cooked and stirred custards, setting happens at temperatures well below boiling. Cooking at too high a temperature or for too long toughens proteins and squeezes out liquid. This makes a baked custard "weep," and a stirred custard curdle--both signs of overcooking."

So temperature matters, as one would expect. But they also claim that it is the rate of heating that matters: "When egg proteins are heated quickly, there's a very small temperature difference (just a few degrees) between thickening and overcooking, so that custards seem to curdle instantly. When heated slowly, this range widens to 10° F or more." This is why some recipes call for use of double boilers for stirred custards, since they allow for a longer "grace period" before reaching the curdling point. Stirring is important for even heating throughout the custard, and not allowing one region (say the bottom) become overheated.

Ok, so now I have my double boiler and low heat. Wouldn't it be great if, with the help of my trusty thermometer, I knew exactly what temperature to look out for to prevent overcooking? This website says I can, with a greatly oversimplified formula. Unfortunately, application of this rule does not work. As described in Experimental Cookery, From the Chemical and Physical Standpoint, "The temperature at which coagulation (thickening) starts varies with the varying proportion of ingredients of the custard and the rate of cooking." So what works for my recipes won't work for someone else's, in other words.

On a related note, a few weeks ago I was reading an ice cream recipe on a popular blog that said to heat the custard to exactly 84° C (183° F). Of course, this was before I read about curdling, and so I thought "Oh great, a guideline for what temperature to heat my custard up to!" Next thing I knew, I had a curdled mess on my hands. What does help is keeping a thermometer in and taking note of approximately when thickening occurs. This way, from that point on you'll have a rough guideline (assuming the same proportions are used) of when to stop.

And lastly, with this newfound knowledge I made a delicious and beautifully pink strawberry basil ice cream! Simply use this recipe by Emeril (I cut it in half), but infuse the milk and cream with bunches of chopped fresh basil leaves for one hour. I also added a pinch of salt and half a packet of gelatin as described here. For presentation, I sprinkled the top with crushed dehydrated strawberries picked out a box of cereal, hehe. Wrong season for this flavor I know, and in summer it would be twice as good and refreshing, but keep it in mind until then!
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7 comments:

  1. Beautiful ice cream, never tried that flavor combo, and yes it seems like a chemistry experiment, but food is.

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  2. Your ice cream looks wonderful! *hit happens and custard curdles, what you gonna do? I use a recipe for ice cream that uses 1 large can drained and pureed peaches and 4 cups thick cream in an ice cream maker. Works like a charm. Recipe is from Hugh Fearnley-Whittingstall.

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  3. Mouth-watering ice-cream. Makes me feel like wanting a scoop now, even in this freezing weather!

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  4. hi!
    glad i found your blog, love the ice cream focused posts...! i am currently trying out the cereal milk ice cream recipe you have, mixture is chilling... though funnily enough i left the pot for a second and came back to it BUBBLING and i feared curdling... !! hopefully it churns up ok, it seems like i may have lucked out on the pre-egg-drop-soup thing...!!

    anyhow, great blog!! :)

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  5. Citronetvanille, thank you! It was delicious!

    Denise, thanks for the recipe tip! Funny that you mention peach ice cream, since that was one of my curdled messes :P

    Mary, thanks so much! It is finally beginning to warm up here, I can't wait to make more summer flavors.

    Lyndsay, glad you are enjoying the blog! I hope the cereal milk works out for you... I actually wanted to try another kind of cereal but haven't had a chance yet. Maybe Fruity Pebbles would be good. Anyway thanks for visiting!

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  6. The building blocks of the any ice cream recipe are neither exotic nor the expensive. You might do well to practice with then the basics until you are happy with the ice cream that the you are making. Then you can get fancy with delicious the flavorings and combinations of the ingredients. Here's a basic vanilla recipe to the get you rolling.


    ice cream maker

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  7. Great blog and nice to read. Very nice blog website! I always enjoy to read your blog post! Very good writing skill.. Keep updating the blog, looking forward for more contents.

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