[HN Gopher] A physicist's guide to ice cream
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A physicist's guide to ice cream
Author : sohkamyung
Score : 97 points
Date : 2025-01-16 12:25 UTC (4 days ago)
(HTM) web link (physicsworld.com)
(TXT) w3m dump (physicsworld.com)
| Xmd5a wrote:
| I started cooking ice cream this summer. I bought an ice cream
| machine that can yield 1L of ice cream in 30 minutes, and
| prepared about 30L, sometimes sourcing material from the garden
| (strawberries, raspberries, cherries, figs and blackberries). If
| you enjoy the taste of fresh figs (which I don't normally because
| of the texture of the fruit) it is an incredible way to preserve
| it.
|
| The best ice cream I made was blueberry + coco cream + lime.
| Highly recommend it. Coco cream as a substitute for water in
| sorbet is an amazing trick.
|
| Shared this with a friend yesterday: 1.
| **Creaminess (smooth, creamy texture)** Creaminess | =
| Cream | + Eggs | + Sugar | Creaminess | = Water | +
| Fresh fruits (high in water) | 2. **Lightness
| (airy texture)** Lightness | = Milk | + Cream | + Eggs
| | + Sugar | Lightness | = Air incorporation (whipping)
| | 3. **Stability (avoiding crystallization)**
| Stability | = Sugar | + Eggs (yolks) | + Alcohol |
| Stability | = Water | + Uneven freezing temperature |
| 4. **Density (weight in the mouth)** Density | = Fats
| (cream, butter) | + Eggs | + Sugar | Density | =
| Incorporated air | + Water | 5. **Melting
| Temperature (softer or harder out of the freezer)**
| Melting Temperature | (softer) = Sugar | + Alcohol | + Air |
| Melting Temperature | (harder) = Water | + Freezing temperature |
| 6. **Sweetness (perceived sugar)** Sweetness | = Sugar
| | + Sweet fruit puree | Sweetness | = Acidity (lemon,
| vinegar) | + Acidic fruits | 7.
| **Crystallization (grainy or smooth texture)**
| Crystallization | = Water | + Poorly mixed ingredients |
| Crystallization | = Fats | + Sugar | + Proper agitation |
| eleveriven wrote:
| Have you tried incorporating herbs (like basil with
| strawberries)? Or you do not like that kind of things?
| Xmd5a wrote:
| Yes, I have, and this is a bad idea (strawberry + mint). The
| problem is that the herbs become harder than the ice cream,
| creating an unpleasant sensation in the mouth. I had a
| similar issue with a toffee ice cream where I tried
| incorporating small cubes, but they became too hard when
| frozen.
|
| One possible solution could be to candy the herbs (though
| it's a lot of work) or to soften the toffee by turning it
| into a kind of cream, freezing it separately, and then
| folding it into the ice cream at the last moment. This
| challenge is addressed in the article,
|
| >We need to add sugar to the fruit to make sure it is softer
| than the ice cream itself - you don't want to bite into ice
| cream and find a hard, frozen berry.
|
| and considering you almost never see artisanal ice creams
| with chunks (unlike industrial ones like Ben & Jerry's, for
| example), this is where culinary engineering becomes
| essential I guess.
| rokkamokka wrote:
| Perhaps if you grind the herbs very finely they'll disperse
| better in the ice cream
| Xmd5a wrote:
| Indeed this is what I do with lemon zests. I put them in
| a blender with the juice for 10 minutes at maximum power
| (as a result, the mixture must become hot). Add two egg
| whites beaten into stiff peaks for 3/4L, and you'll get
| the softest, tastiest lemon ice cream you've ever eaten.
| 1cool wrote:
| If one is too lazy to infuse, it's nice to add homemade
| caramel or compote. Snacks like Lotus biscuits are
| excellent too.
| jordanwallwork wrote:
| Or infuse them in the milk/cream and then strain out?
| seec wrote:
| If you don't care about having the bits for texture and
| only care about the taste you could infuse the cream. Heat
| the cream (stop before boiling of course), add the bits,
| let it rest for a while and then sieve it. I will add some
| time but it should work.
|
| I'm also not a fan of ice cream with solid stuff. If you
| can't lick it pleasurably, it's not really ice cream in my
| book.
| prpl wrote:
| I would blend the herbs in rum, then strain and use the rum
| with simple syrup.
|
| Similar to this: https://www.seriouseats.com/dave-arnolds-
| thai-basil-daiquiri...
| zo1 wrote:
| Thank you very much for this! I remember eating a very "cheap"
| icecream as a kid, that was more "ice" or "frozen" than the
| creamy (expensive) goop I find everywhere these days. I think
| it's down to a combination of less creaminess, and more
| crystallization (to follow your list). But this kind of concise
| guide or explanation really let's me try to recreate that
| texture, as I don't think it's something that anyone would
| "sell" traditionally.
|
| The ice-cream was "cheap" I think because it was made in a
| "failing" country that still had a relatively functioning dairy
| and manufacturing chain, so they were doing their best to still
| make icecream whilst dealing with the loss of key ingredients
| and dwindling margins stemming from the economic situation.
| zabzonk wrote:
| that would be a sorbet?
| zo1 wrote:
| Might be? But I've only ever had fruity or flavored
| sorbets. So maybe I just need to find one that's leaning
| more on the plain/traditional ice cream flavors like
| vanilla and chocolate.
| xandrius wrote:
| The worst offender is when the ice-cream feels "airy". Icy is
| nice for fruity bases, while not great for creams.
| quesera wrote:
| Airy ice cream is also lighter. Beware pints that weigh
| less than expected. At a minimum, it indicates a ton of air
| whipped into the mix. But it's also a decent proxy for low-
| quality ingredients or garbage fillers.
|
| In the grocery store / mass market context, it's hard to do
| much better than Haagen-Dazs. Just be aware that their
| "pints" are now only 88% of a pint (this baffles me -- are
| the ingredients really a meaningful contributor to total
| COGS?).
| xandrius wrote:
| I know this is a simplified version but sugar is not detailed
| enough (different types of sugar, like dextrose), also I see no
| mention of carob seeds, also very important to get a creamy
| texture.
| gunian wrote:
| kind of weird question is it cook? does one cook ice cream?
| always assumed cook implied fire or some sort of heat source
| hansvm wrote:
| The cheap answer is "yes" -- see custard ice creams as an
| example.
|
| Typically though, "cooking" requires heat, and most non-
| custard ice creams wouldn't be cooked. Even in the same
| phrase when talking about cooking other things, you'd say
| something like "I'm cooking steak and also making ice cream."
|
| I'm sure some regions use the word differently, and adding a
| bit of ambiguous context might make on-the-fence regions more
| likely to use "cook" for cold-prepared dishes. E.g., if you
| talk about cooking dinner or cooking a meal and then list the
| things being prepared (one of which is ice cream), the verb
| "cook" is, in some sense, being applied to the ice cream.
| That ambiguity can color the verbs you subsequently choose
| when referring to just the ice cream.
| krisoft wrote:
| > does one cook ice cream?
|
| Yes. Many recipes require heating of the ingredients.
|
| Here is one example picked randomly:
| https://www.bbcgoodfood.com/recipes/ultimate-vanilla-ice-
| cre...
|
| "Step 4: Return the pan to a low heat and cook, stirring all
| the time with a wooden spoon, for 8-10 minutes, until the
| custard is thick enough to coat the back of the spoon."
| xattt wrote:
| Short of constantly stirring a pot full of the ice cream
| custard, do you have any solutions for getting the mixture up
| to temperature without scalding the milk/cream?
| holowoodman wrote:
| The best ice cream recipe ever I got from a physicist:
|
| Cream + sugar + vanilla, stir until dissolved. Slowly add liquid
| nitrogen while stirring fervently until sufficiently frozen.
|
| The stirring in of the liquid nitrogen not only freezes the
| cream, it prevents any cristallisation and fluffs up the ice
| cream by evaporating. Truly delicious!
| oakwhiz wrote:
| I can confirm that this works and is delicious.
| xxs wrote:
| if you have LN2, you can add high spirits as well -
| bitter/sweet liquors are a classic in that combo.
| oakwhiz wrote:
| You can add too much liquor and it will still freeze nicely.
| Spiced rum was pretty good.
| bruce343434 wrote:
| How much of each?
| holowoodman wrote:
| Just look up any ice cream recipe. Doesn't really matter.
|
| I've used 1l of plain cream, 100g of sugar and the marrow of
| 1 1/2 vanilla pods.
| e40 wrote:
| Add sugar to taste, while liquid. IMO you can never add too
| much vanilla.
| soegaard wrote:
| The fat content seems too high. Don't you get a film of fat
| covering the top of you mouth?
| holowoodman wrote:
| Depends on the cream you use. But basically it doesn't really
| matter, you can also use milk, even skimmed milk. Any liquid
| icecream-mix works, only chunky stuff is problematic.
| haliax wrote:
| Where do you get liquid nitrogen as a home cook? I've tried to
| get my hands on both that and dry ice without any luck
| Theodores wrote:
| my view of ice cream has changed over time. I grew up close to
| the biggest factory for ice cream in the UK where it was adjacent
| to the biggest bacon factory in the UK.
|
| The myth at the time was that the fat from the bacon went next
| door to the ice cream factory. At the time the label just said
| 'animal fats' rather than 'dairy' so there was nothing to dispel
| the myth.
|
| Since then the formulation has changed, now you get the usual
| palm oil. As far as ultra-processed foods go, is there anything
| worse than commercial ice cream? You have got animal fats or palm
| oil to block your arteries, refined sugar to spike your glucose
| and lots of emulsifiers and other 'e numbers' to disrupt your
| digestive tract?
|
| Most ice cream is sold in tourist venues where the vendor knows
| he will never see the customer ever again. There is zero
| motivation to make it a healthy product or to use quality
| ingredients when you are not expecting repeat customers.
|
| In other developments, there is a move to have more efficient
| freezers for ice cream in stores, which means changing the
| temperature so it does not need to be stored at such a low
| temperature. The likes of Unilever can spend a fortune on the
| food science to get the temperature up, to roll out new freezers.
| BugsJustFindMe wrote:
| > _There is zero motivation to make it a healthy product_
|
| Heh. I mean, uh, oh no!
| altacc wrote:
| While clearing out an old tub of ice cream I noticed that
| industrial ice cream doesn't melt in the same way as 'real' ice
| cream. It holds its shape well beyond what you'd expect. Left
| at room temperature real ice cream puddles, industrial ice
| cream slumps. There's emulsifiers and stabilizers that keep the
| consistency for a larger range of temperatures, so that's it's
| soft to scoop at -18C whereas real ice cream is as hard as
| concrete. The ingredients list includes things such as whey
| powder rather than milk. Like so many ultra processed foods
| it's just cheap powdered ultra processed ingredients held
| together and flavoured by additives.
| quesera wrote:
| I have seen scoops of cheap ice cream, accidentally dropped
| onto pavement on a hot sunny day in the Southern US, maintain
| their scoop-like shape for hours.
|
| Cheap ice cream is not ice cream. Do not eat.
| skyyler wrote:
| >Cheap ice cream is not ice cream
|
| Most of the UK's "ice cream" would be called Frozen Dairy
| Dessert in the US.
|
| In the United States, cheap ice cream is quite literally
| not ice cream. It's "frozen dairy dessert".
| racl101 wrote:
| > Since then the formulation has changed, now you get the usual
| palm oil. As far as ultra-processed foods go, is there anything
| worse than commercial ice cream?
|
| The ice cream that Walmart sold from its own personal line was
| messed up. It did not melt as fast as other ice cream and was
| oily.
|
| I'd rather eat no ice cream than eat that.
| amelius wrote:
| My local supermarket only sells the basic flavors vanilla,
| strawberry and chocolate. But then they sell dozens of variants
| of Ben and Jerry's and similar brands. I wish this was the other
| way around. Just give me boxes of single flavors like in the
| Italian gelaterias.
|
| I guess supermarkets get higher margins on B&J's :(
| telesilla wrote:
| I completely agree. It's difficult to get quality vanilla ice
| cream except at a gelataria or fancy market shop. Reading this
| thread however makes me brave enough to try making my own once
| summer appears.
|
| I'll probably go for something inconvenient so I need to pre-
| freeze the bowl and thus avoid an unhealthy constant flow of
| ice cream, but tech these days seems pretty good to make
| homemade gelato:
|
| https://www.seriouseats.com/the-best-ice-cream-makers
| sk5t wrote:
| Costco's "super premium vanilla" is quite nice---better than
| any other mass market vanilla.
| mongol wrote:
| Last summer I experimented making ice cream without ice cream
| machine. The principle I used was to freeze it in plastic bags,
| take them out once or twice to "massage them" and then to squeeze
| them out into a frozen bowl where they rest in the freezer until
| eating time.
|
| The recipes are important too of course. The sugars need to be a
| mixture of fructose and dextrose. Also used a stabilising agent.
| But eventually I could create really good ice cream with a
| minimum of equipment.
| baruchthescribe wrote:
| I started making my grandmother's recipe again recently and it's
| amazing and amazingly simple. A pint of cream, a tin of condensed
| milk and a teaspoon of vanilla extract. Whip the cream until it
| lightly peaks, stir in the condensed milk and the vanilla and
| freeze for at least 4 hours. Done. You can add choc chips or
| whatever flavor you want at the condensed milk stage.
| Blackthorn wrote:
| The basic Ben& Jerry's recipe in an ice cream machine is pretty
| much unbeatable if you're looking for traditional ice cream. On
| the other hand, I've tried, without much luck, lower calorie ice
| creams using substitute sugars like allulose. Unfortunately, they
| haven't turned out very well. It really is the combination of
| real sugar, fat, protein, and all that that comes together in the
| cold to make the magic happen.
| buu700 wrote:
| In my experience after a decade of trial and error, inulin
| fiber sweetened with stevia and monk fruit[1] is pretty much a
| perfect sugar substitute. If anything, the texture might be a
| little better than sugar.
|
| Inulin is slightly tricky to work with because it clumps up
| easily when it comes into contact with liquid (likely for the
| same reason, when baking with it I prefer ghee to butter), but
| it mixes into the heated custard base on the stove without too
| much trouble as long as you stir well while pouring it in.
|
| Another tip that's worked well for me: instead of milk or half-
| and-half, I use a 50:50 ratio of heavy cream to egg white +
| coconut water. In other words, I use whole eggs and then add an
| amount of coconut water that matches the difference between
| volumes of heavy cream and egg white. I don't recall offhand
| how the math on that works out (it's somewhere in an old
| ChatGPT log that I've been meaning to properly document), but
| it's a lot easier than separating yolks and it gets a great
| result with less sugar than milk or half-and-half.
|
| 1: https://www.lowcarbfoods.com/low-carb-white-sugar-
| sweetener-...
| NegatioN wrote:
| I wonder if that's at all related to different sugars
| configuration at different temperatures as described by
| AppliedScience [0].
|
| Maybe there are other substitute sugars out there which work
| well at low temperatures?
|
| 0: https://youtu.be/kiuXasyB3L0?si=b_-6iNw1TD35alG4
| yapyap wrote:
| History of Ice Cream is starting to sound realer by the day
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