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Feb 16, 2012 04:57 PM

Questions after making coconut milk ice cream

So I looked up some ice cream making recipes, and have been making ice cream using coconut milk + egg yolks in a double boiler + vanilla extract + stevia + ice cream maker, and I have a few questions since I'm still generally quite new to cooking and think understanding the reasons behind the steps might help me make it better.

1) What exactly is the science behind the custard making. i.e., why exactly am I heating the mixture up? Is it for food safety reasons (raw eggs) or is it for something specific to the ice cream making process? This is especially in regards to the instructions that I'm supposed to cook and whisk until it's custard-like, and I'm not sure I'm getting to that point. So is it because the heat isn't high enough or I'm not whisking enough (and why the need for constant whisking?)

2) I noticed at high enough temp and/or not enough whisking, it seemed like I was seeing a "skin" form on top of the liquid and the sides of the bowl from evaporation (the sides are probably from evaporation and the mixture drying there). Am I doing it wrong/what should I do then?

3) After the ice cream maker was done, I put the mixture in an airtight container and froze it for a day. It seemed kinda gritty to taste, is this because of ice crystals, if so, what can I do to make it even smoother? (I only put the custard in the fridge for about 3 hours after cooking). The vanilla extract also has some alcohol, could that be responsible?

4) Since I'm using canned coconut milk, I'm noticing that the cream tends to separate from the water. Would it be even better if I just scooped the cream out and threw away the water (less water, less crystals that can form?), or will that ruin the ice cream in other ways?


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  1. #1: you are heating the egg mixture to thicken it. Not all ice cream bases are cooked. I can't comment on those made with coconut milk, but there is definitely a difference in texture and flavor in cooked vs. uncooked base ice creams. Which is better is a matter of taste, IMO.
    Depending on the volume of eggs to liquid, its unlikely you're going to get an actual thick custard. Even actual custard is still somewhat liquid when hot. Basically you just want to see it coat the back of a spoon, so that when you drag your finger through it, the line stays.
    #2. Overcooking/overheating custard will make it curdle---basically the eggs get scrambled. In your case, I suspect this is what got you the grainy texture in the finished product. (That could be all or in part to how it was churned and frozen, too.) Sugar is a BIG molecule and when it's mixed with eggs it spreads the proteins apart and acts as a stabilizer, letting a custard thicken without the eggs "scrambling" I suspect using stevia negates this factor, although I have not cooked with stevia in this particular scenario to know for sure. I have made custards with coconut milk and not noticed much of a difference, so that is less suspect.
    The constant whisking is to keep the mixture at as even a temperature as possible to keep it from curdling. I think you probably just cooked it too long and/or it got too hot.

    #3: My experience is thinner in this area. I know that not enough fat and sugar or both will give a grainy texture, especially in a home machine because you're not incorporating air and controlling temperature as strictly as in a commercial setting. Likewise, there's no weird texture improving ingredients in a homemade product. IME, however, homemade ice cream can be every bit as smooth and creamy as commercial BUT it depends on the recipe and ingredients. Again, sugar is a big factor in this.
    #4: Well, yes, but IME raising the fat content of an ice cream base only improves it up to a point. Beyond that it comes out with a greasy mouthfeel. You could try what you suggest and see what you think. I assume you're using regular coconut milk, not light. I think a better approach would be to reduce the liquid (vs. tossing it) before going on to the eggs/custard step. That way you retain whatever flavor and solids it contains.

    I actually think your biggest issue here is the absence of sugar.

    2 Replies
    1. re: splatgirl

      Sorry to be pedantic, but sugar - even sucrose - is small compared to a protein. Perhaps ypu were thinking of starch, which is bigger than most proteins.

      1. re: Joebob

        The size relative to a protein isn't what matters. Perhaps it would have been more accurate to say that it's the nature of the sugar molecule moreso than it's size that is protective. Sugar surrounding the egg proteins is insulative, both chemically and mechanically.

    2. This is a bit odd, but while I hate to do it, I am going to answer your question by asking a question.

      Why are you using coconut milk to make a custard-based ice cream?

      The reason folks use coconut milk (instead of dairy) is because they want a vegan alternative to your typical ice cream, which means no cow milk and no eggs.

      I don't think I've ever recalled seeing or having a coconut milk ice cream that is custard based.

      But that said, if you are going to use coconut milk with a custard base, you should really consider using a binder of some sort given the texture and viscosity of coconut milk. Arrowroot is something I would consider first as a binder.

      3 Replies
      1. re: ipsedixit

        Not true. I make a coconut ice cream calling for eggs to make a custard with some coconut milk plus a smaller amount of half-and-half.

        1. re: ipsedixit

          I was kind of thinking this same thing.
          For the eggs, yes, but heating coconut milk probably has no real benefit or point, IMO.

          With a dairy milk based ice cream mixture, heating is partly denature those milk proteins--like scalding milk for a bread dough. Doing so smooths out an ice cream and changes the taste a bit, for better or worse.
          The presence of eggs distracted me--I assumed in this case heating was for the egg thickening aspect and the use of coconut milk for the flavor.

          To my eye full fat coconut milk is at least as viscous as cream so that part shouldn't be an issue. I have had excellent results making true custards with coconut milk in place of dairy milk with no other alterations.

          1. re: ipsedixit

            Some people are lactose intolerant, but can have eggs. Like me.

          2. I make coconut milk ice cream also. I think heating it is to incorporate the ingredients (mostly sweeteners) so the end product is smoother. When I make it just with stevia- I don't heat it.

            I have added a tiny bit of Xanthan gum, agar agar, have made it without eggs and have added coconut cream to the mix too. I have been happy with all of my experiments....finished every one :)

            Ipse, coconut ice cream is not only delicious- it is healthy for those who limit sugars, are low carb or sugar free in their diet and/or want to add some fabulous lauric acid to their diet.

            I always make coconut ice cream that is sugar free. It is also a typical Thai dessert (usually served with roasted coconut) and it is a really nice dessert to make after a spicy Thai (or similar food genre) meal. I also like it with cocoa and nuts in it.....mmmmmmmm.....

            3 Replies
            1. re: sedimental

              Could we please have one of your simpler vegan recipes?

              1. re: Joebob

                I don't usually follow a recipe, I "experiment".......... but, this is kind of a "base" ratio recipe to start with. It is extremely simple:

                3 cups of coconut milk
                1/2 cup of sugar (or other equivalent sweetener)
                3/4 cup water

                *toasted coconut, lime wedge (optional)

                If using sugar, heat it with the water to make a simple syrup and make sure everything is dissolved. Let cool, then start mixing the syrup with the coconut milk, mix half and taste it. You want it "overly sweet" because it tastes less sweet when frozen. I usually use the entire amount of syrup. You really have to adjust for liquid sweeteners. That's it.
                Pour into ice cream maker. Serve scoops in bowls sprinkled with toasted coconut and served with a lime wedge.

                1. re: sedimental

                  The best coconut ice cream I've ever had had little chunks of fresh coconut in it. I'll add some to your recipe.

            2. Perhaps try a few things:

              Replace half of the stevia with sugar (by sweetening power, not volume)

              Bring the custard mixture just below a simmer and stop cooking.

              immediately pour the mixture into a bowl set in an ice bath.

              Whisk in a tablespoon of vodka while cooling.

              1. I'd also try using different coconut milk brands. I use "A Taste of Thai" coconut milk and it usually comes out the smoothest.