Rum Raisin—A Holiday Classic

Let’s take a look at Rum Raisin, an old favorite. I’ve chosen this topic for 3 reasons:

  1. Nostalgia: this was one of my favorites when I was a little kid. It’s supposed to be a grownup flavor but I just loved it. Other people have told me they had the same experience. Even people who as adults don’t like rum. 
  2. Craft: our earlier article on booze-flavored ice cream does not address how to handle inclusions that are macerated in booze (e.g. rum-soaked raisins). Turns out this is not a trivial problem. 
  3. Defense of all that is good and just and true: online trolls and bots (some even posing as friends of mine) have been badmouthing this unimpeachable flavor. It’s time to set the record straight. 

I’m going to focus on item #2, craft, because this is more our focus than nostalgia or self-righteous ranting. Maybe I’ll start another blog that features fist-shaking at clouds.

At issue is our recommendations on spirit quantities. In the earlier article, our recommendations were based partly on flavor, and partly on maximum levels of alcohol that would allow the ice cream to freeze at ordinary serving temperatures. And at ordinary ice cream machine temperatures. But when you make a flavor like rum raisin (or prune & armagnac, dried cherry & kirsch, fig & boukha, or whatever & whatever), you typically macerate the dried fruit in the booze first. This is to make them plump and soft, to keep them from freezing into little rocks, and, of course, to make them boozy-delicious. 

Maceration Is Not A Sin. But There Are Side Effects

The problem is, we don’t know for sure how much of the alcohol that we infuse into the fruit is going to stay in the fruit, and how much is going to leach out into the ice cream base, adding anti-freeze power to the spirits we’ve already mixed in there. This is a potentially significant problem, because dried fruits soak up a lot of booze. 

For example, this recipe includes 150g raisins per 1000g base (based on the proportions I see most pastry chefs using), with a 1:2 ratio of rum to raisins (based on experiments). This means 75g of rum to macerate the raisins.

As a recap, here’s the advice on alcohol levels we offered in the old article:

Quantity of Spirits in 1000g total recipe:

With most hard liquors: 
75g is very strong.
45–60g gives nice flavor and a kick

With most liqueur and fortified wine:
45–60g is often plenty

If we follow these recommendations blindly, might be tempted to put 75g of rum into the raisins, and another 75g of rum directly into the mix. intuition told me this would be a bad idea … we might end up with something that would work better as an intoxicating sauce, or an accelerant to light crêpes on fire. 

A Solution

How do we calculate the right amount of rum, when boozy fruit is involved? I started by macerating the raisins overnight in their 75g of rum (50% by weight), and see what they looked like in the morning. And then I made some wild guesses.

The raisins had absorbed all but 24g of the rum. I strained this off and added to the base. I guessed that that the raisins would leach another 15g to 25g or so into the base, which brought the total rum in solution to 49g. My target is 60g maximum, so I added another 11g. 

Here are the numbers (made with Appleton Estate 8-year rum, 43% ABV):

Rum absorbed by raisins: 51g

Rum strained off of raisins: 24g
Rum estimated to leach from raisins into base: 15g – 25g
Rum added directly to base: 11g
Total rum in solution: 50 – 60g
Total rum in recipe (solution + raisins): 86g

How did it work out? I think it was perfect. It had a nice strong rum flavor, without tasting like a cocktail. It was soft at serving temperature, but not soupy. I would not go stronger than this; it would be challenging to get it to freeze properly. 


Rum Raisin Ice Cream Recipe

Makes ~1.2 liter
60g / 1000g bourbon. 2.1% to 2.5% alcohol by weight. This will be soft; 60% – 62% ice fraction @ -14°C.

Requires immersion circulator and blender. High-powered blender or homogenizer preferred.

365g Whole Milk
360g Heavy Cream 36%

55g Skim Milk Powder
55g Sucrose
30g Sucrose (to caramelize) 
35g Dark Brown or Dark Muscovado Sugar
1.6g Stabilizer blend or
        0.9g Locust Bean Gum
        0.46g Guar Gum
        0.23g Lambda Carrageenan

36g Egg Yolk

150g Raisins
75g Rum 43% ABV
11g Additional Rum

1000g without inclusions
1150g Total

-Macerate raisins in 75g rum at least 8 hours. Stir occasionally.
-Strain raisins and collect rum. Weigh it. Add fresh rum (if needed) to bring total rum to 35g. -Seal in a container.
-Seal raisins in separate container.

-set immersion circulator to 77°C / 171°F

-thoroughly mix powdered ingredients. use a 0.01g scale to measure stabilizers.
-separate eggs and set yolks aside. freeze whites for other use.

-measure milk into blender.

-make caramel. add small portion of water to the small portion of sugar in a saucepan. cook to a medium caramel. Stop cooking by setting pan into a shallow tray of water.
-deglaze with a portion of the milk from the blender. scrape all caramel from bottom of pan.
-pour back into blender with the rest of the milk.

-set blender speed to create a vortex; add powdered ingredients. cover and blend on high for 30 seconds to disperse the stabilizers
-add cream and yolks. briefly blend again

-pour mixture into 1gal ziplock bag. Add weight (optional). evacuate the air before sealing.
-cook in water 77°C bath for 45 minutes.
-gently agitate bag after 5 minutes and 15 minutes. if you see air accumulated in the bag, release it, and carefully reseal bag.
-mix will be pasteurized (pasteurization time after reaching 75°C is under 2 minutes).

-remove bag from water bath. open and pour hot mix into clean blender container (or a square container if using a homogenizer or stick blender). remove weight, if using. Use bag to squeegee mix off the weight. temporarily seal bag and keep handy.
-blend on highest speed for 30 seconds to homogenize.
-add rum. blend briefly.
-pour mix back into ziplock bag.

-chill bag in ice water bath (use ice bath to evacuate the air when sealing bag). carefully agitate to cool. Try to cool to refrigerator temperature.
-refrigerate at least 8 hours, below 38°F / 3°C to age mix / pre-crystalize fat.

******
-pour into ice cream machine: snip off bottom corner of bag, and squeeze out mix as if using a pastry bag.
-spin in the ice cream maker. With a mulitispeed machine, use a slow setting (this recipe works best with a low overrun). Ideal drawing temperature is 23°F to -19°F / -5°C to -7°C. When temperature gets into this range, and rate of cooling has plateaued, you’re probably done.
-Add raisins. Run machine just long enough to mix in.

-harden for several hours (preferably overnight) in a cold freezer. freezer should be set to -5°F / -20°C or lower.

Total Fat: 15%
Milk Fat: 14.2%
Total Solids: 38%
Solids Nonfat: 23.1%
Milk Solids Nonfat: 10.3%
Acidity: 0.17%
Alcohol: 1.7% (before raisin addition); 2.1%-2.5% after
Stabilizer/Water: 0.27%
Egg Lecithin: 0.29%
POD: 120 / 1000g
PAC: 390 / 1000g
Absolute PAC: 722 / 1000g
Rel. Hardness @ -14°C: 63


Recipe Notes

Rum is made from sugar (cane juice, molasses, or some combination—Appleton Estate is made from molasses). To accent the sugar-derived flavors, I borrowed ideas from our Quartet of Dark Sugars recipe (scroll down) substitute a dark brown sugar for some of the white sugar, and caramelize some o the white sugar. These refinements are optional, but I enjoy the added depth of flavor. 

Since you won’t know in advance how much rum your raisins will soak up, be sure to complete the maceration process, and strain the excess rum off your raisins, before mixing up the rest of the base. You’ll need to see how much rum you strain off. And you’ll need resist drinking the raisin-steeped rum. 

A Note on Sugars and Freezing Point Depression

As discussed in our article on sugars, we often tweak the sugar blend to get the right combination of sweetness and hardness. Usually we’re trying to get the ice cream adequately soft without it being too sweet, so we mix in sugars like dextrose, which are high on freezing point depression and low on sweetness. But with booze flavors, we face the opposite problem, since alcohol is a powerful anti-freeze. Ideally we’d have a sugar that’s sweet but has low freezing point depression. Outside of using artificial sweeteners (which we’d like to avoid) or stevia (which has a strong flavor), we don’t have anything like this. So we stuck with sucrose, used relatively little, and produced a soft ice cream that’s typical of most boozy ice creams. Just be sure to keep your freezer cold, and get it to your guests in a hurry. 

Template For Creating Your Own Booze-Macerated Flavors

  • Start with 150g dried fruit per 1000g base. The dried fruit is NOT considered part of the base recipe (it does not dissolve) so your total recipe weight will be 1150 g. 
  • Macerate the fruit overnight in half its weight in booze. 
  • Strain off and measure any unabsorbed booze from the fruit. Reserve this for your base. 
  • Decide how much total alcohol you want in your base. I’d suggest aiming for 2% to 2.5% alcohol by weight.
  • Calculate how much of your spirit you need to achieve this.1 
  • This amount, minus the the amount you strained from the fruit, is the additional spirit you need to add to the base.
  • Use sucrose (table sugar) as the sweetener, or supplement with other sugars that are primarily sucrose (caramel, molasses, maple syrup, etc.). Avoid sugars with higher ratios of freezing point depression to sweetness (dextrose, invert syrup, honey etc.)
  • Keep total level of sugar to around 12% of the recipe weight. If your booze is sweet figure out its sugar content and add correspondingly less sugar. 

 

Notes On Rum

I’d love to be able to write an authoritative treatise on rum; to shine clarifying sunbeams and unlock the secrets of this glorious island spirit.

It’s not gonna happen.  I can offer just one useful generalization: that it’s impossible to make useful generalizations about rum. The topic is too vast. The standards are too few. The nations and cultures and traditions and languages behind it are too many. There is no consistent terminology or taxonomy from one country to the next. Different countries use similar terms to name different things. And different terms to name the same things. 

There are classic cocktails built around a single iconic variety of rum. Use a different rum, it’s a different cocktail. Because there are no other rums in that category. Many rums are essentially in a category of one. Ask a mixologist which rum would be good starter for your home bar, and they’ll likely ask, “what are you trying to make?” If you can’t answer, they can’t help. Other spirits aren’t like this.

For this ice cream project, I picked up some Appleton Estate 8-year Jamaican rum, based on some internet reviews, and what the store had, and some eenie-meeny-miney-moe. It worked out great. But I’m not sure how big an impact the variety of rum makes here. 

When I brought the rum home and tasted it, I liked it, but questioned if the flavors might be too strong in ways that wouldn’t work in ice cream. Specifically, the Appleton has an undercurrent of bitter, burnt notes, reminiscent of blackstrap molasses. I wondered if I should have gone with my 2nd choice, Rhum Barbancourt, which is a Haitian Rum Agricole and might have a subtler, more refined flavor2 (also, the Haitians could use the business right about now). But the sugar and the dairy softened the flavor, and I couldn’t perceive any of those burnt notes. Is there an ideal rum type for ice cream? How big a difference does it make? Further research is required.

If you’ve done your own experiments, please share your experience in the comments. 

History

Where did rum raisin come from? I don’t have a definitive answer. Lore says that its ancestral home is Sicily, where in the early 20th century someone soaked raisins in Málaga (a sweet fortified dessert wine) and churned them into vanilla gelato. Málaga raisin ice cream became a regional signature dessert. Then, as the story goes, someone in the US upped the proof by substituting rum, possibly to celebrate the end of prohibition. Haagen Dazs may be responsible for re-popularizing the flavor in the 1980s. For some reason in this decade, younger generations have turned on the raisin, publicly raining contempt on the humble dried fruit, as well as the enlightened and benevolent few who soak them in rum in the name of advancing our civilization. I wish the kids would stick to fighting autocrats and climate change. Those battles might be winnable. 


1To calculate spirit quantity:

  1. Find your spirit’s alcohol by weight: multiply the published alcohol-by-volume (ABV) percentage by 0.8
  2. Recipe weight X desired alcohol level ÷ alcohol-by-weight

 

2Ok, here’s one generalization that might hold true: most rums are made from at least some portion of molasses, which is the intensely flavored syrup centrifuged off of the sugar cane in the early stages of refinement. Rhum Agricole, on the other hand, is made directly from fresh sugar can juice—a perishable product that requires immediate fermenting and distilling, and which preserves more of the terroir of the cane. Many classics in this style come from Martinique, but you can find others from across the French Caribbean.  

 

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Luan
1 month ago

My signature gelato is Rum raisin itself, and I have this exact problem with not knowing how much alcohol is in my base.
Compare to my other flavor Margarita which has a really good texture and shelf life, Rum raisin has a wonderful taste but experiences lactose crystalization much faster.

To make matters worse, I don’t just macerate the raisin overnight, but water-heat it in a closed glass container, and open the lid to let the alcohol evaporate. I’m doing this because I will add another full amount of uncooked rum into the base thus adding as much “rum flavor” as I can without ruining the texture.
I thought by leaving the lid open for half an hour all the alcohol would be gone. But that is not the case (https://www.foodnetwork.com/how-to/packages/food-network-essentials/cooking-wine-does-alcohol-burn-off#:~:text=The%20longer%20you%20cook%2C%20the,40%20percent%20of%20the%20alcohol.)

And thank you for pointing out that the booze can leak out of the dried fruit. I’ve been ignoring this.
One way I can test this is to make a no-raisin batch (fresh rum + cooked rum), calibrate it’s texture to perfection, and make another batch with soaked raisin added and compare the two.