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!

Homemade Chipwich: Baking a Chewy Cookie

Made with the Thomas Keller chocolate chip cookies, plus strawberry basil ice cream (post coming soon!). Sorry Ode, this flavor turned out awesome I must say, but next time I promise not to be too tired for ice cream making! The chipwiches looked and tasted good, but the cookies (and chips) were too rock-hard. That got me thinking, what's the best way to make cookies suitable for chipwich-making rather than for eating? Because for eating on their own, I like my cookies a bit crisp on the outside, chewy on the inside rather than chewy all around. How to best make them chewy all around?

The first thing I noticed was that size matters--I made two sizes of cookies, one about 2.5 inches in diameter, the other 4 inches in diameter. The 4 inch cookie remained soft the next day, at least in the middle, whereas the smaller cookies became rock-hard. Unfortunately, I used the smaller cookies for the chipwich, which really didn't work very well. I smushed the whole thing just by taking my first bite.

Second, I cooked them all too long for them to be chewy. In order to be chewy, the cookies have to retain sufficient moisture contributed to the dough by the eggs, butter, and brown sugar. Baking the dough for too long in the oven allows for increased evaporation of this moisture, making for an overall drier result. I basically left them in until the edges browned due to caramelization of the sugars in the dough, causing dehydration. So next time, I would want to use a shorter cooking time to preserve that moisture.

And lastly, a thicker cookie would also help. Shorter cooking time would help this, but to affect the thickness in a very significant way, I think the recipe would have to change. Which would subsequently affect the flavor, perhaps in a negative way, something like adding flour to thicken the dough. Well, shorter cooking time and bigger cookie diameter is a start, I suppose. Oh, and smaller chocolate chips. Because the chips were self-cut from a bar, I ended up with quite large chunks--which really hurt your teeth when bitten into frozen. What are your tips for making a better cookie for chipwich-ing? Any favorite chipwich combinations?

Thomas Keller's Chocolate Chip Cookies

I must admit I've been neglecting the blog a bit these days, mostly because of various visitors that have come to stay with me, a gigantic "snowmageddon" that hit, and well, a hint of laziness. The recent snow storm has actually helped me get me off the couch/bed/lab bench and back into the kitchen (due to my school being snowed in for two days, yeah! So there are benefits to having the city wait for snow to melt rather than cleaning it up...). I recently bought Thomas Keller's new book designed for more casual, family-style home cooking, Ad Hoc at Home, and tried my first recipe. Of course it turned out to be a dessert, and something simple: chocolate chip cookies. I was just curious... What do Thomas Keller's chocolate chip cookies taste like?

The recipe was easy enough, although it really took the wind out of me to stir cookie dough without a stand mixer/paddle attachment. For chocolate, he uses a combination of Valrhona 70% and 55% chocolates. I cheated, and added half milk chocolate instead of the 55%. I know, all true chocoholics would turn their nose up at me right now, saying "Milk? Please, who eats that stuff anymore after age 10?" But I really do prefer milk chocolate over dark, even in my cookies. Not sure what that says about me, especially since I do enjoy lots of bitter things, like super-hoppy beer. What's your preference?

I made a few test cookies first, to see if I liked the dough I had or wanted to add anything more to it. First off, I forgot the salt! Terrible mistake, salt is such a big thing in desserts to bring out the flavors properly. Second--and this is probably after years of making the Toll House recipe on the back of the chocolate chip bag--I was missing the vanilla extract. I know, I doubt Thomas Keller uses vanilla extract, or extracts of any kind for that matter, in his cooking. But I ended up adding a teaspoon in anyway--my personal preference.

Overall the cookies were crisp on the edges, chewy in the middle, and tasted delicious. Not overly sweet, like so many of those pre-made dough kinds, and I think this recipe really makes the chocolate you use the star of the show. A lesson to use better chocolate--and more of it--next time. Anyone have their own chocolate chip cookie recipes or tips to share?

Fresh Mint Ice Cream: Introducing Gelatin

A friend recently commented that I've been making only ice creams for weeks now, and I will admit that it has been awhile since I've thought of making anything but. I've become preoccupied with making a better homemade ice cream, especially regarding texture. Taste hasn't been too much of an issue, in my opinion, and I always have a long mental list of new flavors to test out. Last time I made my first gelato, and I thought it was quite successful texture-wise, but I don't like the idea of forever making gelato (I'm more of an ice cream person myself) and also forever using raw eggs. One thing I noticed was that it was nicer coming out of the freezer then my previous custard-based ice creams. Taste was less rich, admittedly, but texture was a bit more scoopable.

Before the gelato, my cornstarch ice cream was a terrible failure. Too pudding-like and melted strangely. So moving on to my next experiment, I decided to give gelatin a try. Gelatin is commonly used in desserts that "set", such as panna cotta, jello, and gummies. According to Wikipedia: "Gelatin is a protein produced by partial hydrolysis of collagen extracted from the bones, connective tissues, organs and some intestines of animals such as domesticated cattle, pigs, and horses." Gross, huh? Try not to think about that when you are eating or using anything with gelatin in it (probably a lot more products than you realize).

It was used as the main stabilizer in the ice cream industry for years, according to Dr. Douglas Goff, before being replaced by cheaper compounds. What's the benefit of using a stablizer? Dr. Goff states that adding a stabilizer increases the viscosity of the ice cream mixture by thickening the unfrozen portions of the water and preventing them from moving through the mix, joining together, and creating big ice crystals when re-frozen. Gelatin powder put into water, for instance, dissolves a little at room temperature, but then melts completely with sufficient heat. When cooled, the mixture then solidifies into a colloid gel--the water being suspended in a protective collagen matrix.

So I decided to use a few sprigs of fresh mint as my flavor (which by the way, gives such an amazing flavor as compared to the mint chocolate types of ice creams you buy at the store), just to keep it fairly simple as I didn't know how the use of gelatin would turn out. I used 2 egg yolks, half a packet of gelatin powder, 1/3 c sugar, 1 1/2 c whole milk, and 1 c heavy cream--along with my usual recipe for making ice cream mix, except I melted the gelatin in after infusing the mint into the milk/cream. Remember that you have to melt the gelatin at sufficient heat to incorporate it throughout the mix.

The results were a success! I found the ice cream more scoopable, yet still rich and creamy, and had firm "bite". Also, it had nice melt-down characteristics--none of that "pudding"-like weirdness that cornstarch gave. Unfortunately, it is not vegetarian, which is the biggest downfall of using it in ice cream (as far as I can tell). Which I assume would be where vegetation-based hydrocolloids like locust bean gum come into play. Anyway, I'm convinced! I now see the benefit of adding a stabilizer into my ice creams. As a temporary fix, gelatin seems to work well, but if I want my vegetarian friends to partake, I'll eventually have to find a substitute. Which is your favorite plant-based hydrocolloid and how do you use it?

Olive Oil Gelato: Gelato vs. Ice Cream

As I've mentioned (and demonstrated) before, I always leave New York City inspired by its bustling and ever-evolving culinary creativity. About a year ago, I went to Mario Batali's Otto Pizzeria and had one of the more revelatory ice cream flavors in my life--olive oil gelato. E recommended it, and I was admittedly skeptical, but since she's usually right about these kinds of things, I took her word for it. It was surprisingly delicious, with the subtle taste of olive oil all wrapped up in soft, sweet cream. I had it a second time from Capogiro, the famous Philly gelateria known for their unique flavors and use of local, fresh ingredients.

So I was reminded recently that this was a flavor I had yet to try my hand at, and plus I had all the ingredients at home. The recipe comes from The Babbo Cookbook, and the first thing I noticed is that the egg yolks are not cooked. As in, it does not require you to make a custard. I know, it isn't ice cream that we're making, but I didn't know that gelato sometimes contains raw egg yolks. Then again, I've never made gelato before, but I had the notion that the only difference is that gelato uses only milk whereas ice cream uses cream and milk.

Another thing I heard was that gelato contains less fat than ice cream. This apparently is true. Wikipedia states: "Gelato differs from ice cream in that it has a lower fat content, typically 3.5% for gelato versus 10-12% for ice-cream." That was another reason why the Babbo recipe baffled me, because it actually contains the same proportion of ingredients as my usual ice cream base does, and that includes cream. Weird.

The only difference then, is that for ice cream I heat the milk, whisk the hot milk into the beaten yolks, and put the whole thing back on heat to cook the eggs which thickens the mixture into a custard. For the gelato, I basically mixed all ingredients together cold, and they even say you can throw into the ice cream maker right away. This means that, because the heating process is missing, the bonds between the yolk proteins do not break (even through "ribboning", as Harold McGee describes in On Food and Cooking: The Science and Lore of the Kitchen), and the usual net-like matrix of unraveled proteins does not form as it does during cooking. Thus the gelato mix has a lower viscosity than traditional custard (which can be seen immediately upon making the mix), which affects "body and mouthfeel" of the eventual frozen product.

Qualitatively, the gelato certainly did not freeze as firmly as previous ice creams had, and had more of a "whipped" quality. But overall, it still turned out decently, but I would warn those that try to actually use a high quality olive oil. I used a mediocre olive oil because it was what I had on hand, and it gave me a bit of a strange aftertaste. Any tips on making gelato, feel free to contribute!

Nutella Ice Cream: No Eggs, Just Cornstarch

Recently I've been giving some thought as to how I can improve the texture and/or flavor of my ice creams, and while reading some articles online, I stumbled upon this recipe for cornstarch ice cream in the New York Times. Sounds gross, doesn't it? It actually is an egg-less ice cream with cornstarch in place of the more traditional egg yolks. Then you may feel free to add whatever fruits etc. you choose, without (as some claim) any yolks affecting the intended flavor with their egginess. Not to mention it's a lot easier and faster to drop in a spoonful of powder and heat, than it is to separate yolks and proceed to watch/stir the custard ever so carefully to prevent curdling. And lastly, eggs (especially good quality ones) can get expensive, also considering that some recipes call for as many as six yolks.

Then I started thinking about why this would be, why can you substitute cornstarch for yolks? And what are the downsides of doing so? Well before going any further, I can tell you from a non-scientist's point of view that I was not pleased with my cornstarch ice cream at all. I followed the New York Times recipe exactly, except I added 1/2 c Nutella and let it melt while heating the cream/milk. Ever since I returned from Rome, I've been meaning to make some ice cream with the Nutella I bought there. Actually it isn't Nutella brand, but an Italian kind of "Crema Gianduja". I know, what a waste of 1/2 c Nutella. I should have tested the recipe with vanilla first, but I guess I trusted that it would work out as well as it did in the video.

Before even freezing the ice cream, the custard already had me worried because it had quite a different texture than the egg custards I've made in the past. It reminded me of chocolate Jello instant pudding, with its glossy finish and light consistency. Not that egg custard isn't shiny, but this was really glossy. Plus, the use of cornstarch seemed to have caused the custard to lose its "richness," in both taste and texture.

After freezing, I have the same complaints as when it was unfrozen--glossy, loss of richness--and while the flavor was ok, I had a hard time eating it as noticed it melting into a pudding-like thing. One good thing, it certainly scooped easier right out of the freezer than the egg ice creams. Perhaps I used too much cornstarch? Or did the Nutella affected the custard in a negative way? I haven't written off the use of cornstarch in ice cream completely, but I will certainly put less than 3 Tbsp of it next time.

If anyone has a good or bad experience with cornstarch ice cream, please share! Ok, enough of the qualitative talk, now I want to know what the quantitative difference is between using yolks vs. cornstarch. To be continued...

New Year, New Look!

Hopefully 2010 will be full of even more interesting experiments in the kitchen. Notice the new look of the blog, banner courtesy of E!