11 MINUTE READ
Ice cream generally contains seven categories of ingredients: milk fat, milk solids-not-fat (the lactose, proteins, minerals, water-soluble vitamins, enzymes, and some minor constituents), sweeteners, stabilizers, emulsifiers, water, and flavours. In this post, we’ll be looking at the role of fat in ice cream.
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Table of Contents
Fat modifies the release and perceived intensity of flavour, increases the richness of flavour, is a good carrier of fat-soluble (i.e. those that dissolve easily in fat) flavours, produces smooth texture by lubricating the palate, helps to prolong shelf life by reducing recrystallisation rates during storage, aids in producing desirable melting properties, and contributes to the stability of air bubbles, (1 2 3 4 5).
1. The effect of fat on flavour
Flavour can be best defined as a combination of taste, odour, texture, temperature, sight, and even sound, experienced by an individual when eating or drinking. Flavour results from two types of molecules: those that are volatile (i.e. small and light enough to evaporate from their source), which are responsible for odours; and those that are non-volatile (i.e. don’t easily evaporate at room temperature), which are responsible for taste.
TASTE AND ODOUR
When we eat and drink, volatile food molecules fly out of the food and into the air in our mouth, which allows them to rise into the nose as we breath out, particularly just after swallowing, where they are detected. Non-volatile molecules, on the other hand, cannot be easily smelled and must be dissolved in saliva to be detected by molecular receptors located in the taste buds on the tongue, and to a degree on the sides and back of the mouth, to give food its taste. Taste refers to five perceptions: salty, sweet, sour (acidic), bitter, and umami. These five perceptions are perceived much more slowly than odour (6). It is generally believed that aroma is more important than taste in determining overall flavour, a generalisation that can be easily demonstrated by observing the difficulty in distinguishing between an apple and a pear if our nose is blocked by a cold or pinching fingers.
1.1. The effect of fat on taste and odour
Fat influences the rate of flavour release, the perceived flavour intensity, and the duration of flavour. Generally speaking, a higher fat content leads to a slower release of flavour, lower flavour intensity, and a longer duration of flavour (7 8 9 10).
1.1.1. Flavour release
Most volatile odour molecules are lipophilic (i.e. they dissolve better in fat than in water); this is why cooks make prepared flavour extracts by infusing herbs and spices in oil, not water. Fat binds (hangs on to) these dissolved volatile odour molecules during eating so that their odour appears more gradually and persists longer. In the absence of fat, lipophilic odour molecules are poorly bound to the food, which means that relatively more volatile odour molecules are released into the mouth, giving sorbets, fat-free, and low-fat ice creams a faster release of flavour that disappears more quickly.
Frost et al.10 examined ice creams with different fat levels (3%, 6%, and 12% milk fat) and flavourings (berry, coconut, banana, and vanilla). The researches showed faster increases and decreases in flavour perception with lower fat levels. Similarly, Li et al.8 showed that increasing fat concentration (0.5%-10%) prolonged the time required to reach maximum vanilla intensity.
1.1.2. Flavour intensity
The amount of flavour released from food depends on the retention of volatile odour molecules by the food’s components. Fat holds onto volatile odour molecules during eating so that more odour molecules go down the throat with the fat rather than travelling up into the nose with the breath. Fat also coats taste receptors in the mouth, thereby hindering taste molecules from moving to the taste buds. There is, therefore, a reduction in the perceived flavour intensity with increasing fat content. Conversely, as the fat content is decreased, more volatile odour molecules are released from food, thereby increasing the maximum flavour intensity. This point has a practical application for ice cream producers as the amount of flavour added to an ice cream mix with a lower fat content can be lower than that added to one with a higher fat content to trigger the same flavour release (11).
Hyvonen et al.12 investigated the effects of dairy and vegetable fats (0% to 18%) on the perception of strawberry flavour release and melting of ice cream. Significant differences in aroma and flavour were perceived between fat-free and fat-containing ice creams: intensity and sharpness of strawberry aroma and flavour were greater in the fat-free samples. However, the researchers found only slight effects of fat content on the rate of flavour release and flavour intensity between low fat (9%) and high fat (18%) strawberry-flavoured ice creams. Similarly, Li et al.8 did not find a significant effect of fat on the maximum intensity of vanilla with increasing fat concentration (0.5%-10%).
The table below shows the ratings for nine sensory attributes of nine strawberry-flavoured ice cream samples containing different fat type and fat content. From Hyvonen et al.12.
1.2. Source and carrier of flavour
Milk fat is both a source and carrier of flavour. As a source of flavour, milk fat contributes significantly to the buttery, creamy, and ‘rich’ flavour of ice cream (13). Moreover, milk fat reacts with sugars and proteins, yielding sugary and caramel-like notes in full-fat ice creams (14). As previously mentioned, most volatile odour molecules dissolve better in fat than in water; only a small portion of volatile odour molecules are hydrophilic (i.e., they dissolve better in water). This makes milk fat the main carrier of added flavours.
2. Smooth and creamy texture
Ice crystal size is a critical factor in the development of smooth and creamy ice cream (16). Smooth and creamy ice cream requires the majority of ice crystals to be small. If many crystals are large, ice cream will be perceived as being coarse or icy. Milk fat contributes to the smooth and creamy texture of ice cream by lubricating the palate, thereby reducing the perception of coarseness due to large ice crystals. Prindiville et al.5 investigated the effect of different fat contents (0.5%, 4%, 6%, and 9%) on the sensory properties of chocolate ice cream. The researchers found that the two ice creams containing the most fat were significantly creamier and smoother than were the other ice creams. Similarly, in a study of the influence of fat, sugar, and non-fat milk solids on taste, flavour, and texture, Stampanoni Koeferli et al.13 reported that the addition of fat increased buttery, creamy, and mouth-coating characteristics and reduced ice crystal perception.
2.1. Optimum fat content for flavour and texture
McCandlish et al.26 predicted optimum levels of fat for overall, flavour, and texture preferences to be 11.75%, 13.51%, and 10.2% respectively. Guinard et al.15 found optimum levels of sugar and fat in vanilla ice cream were 14.3% and 14.8% for overall liking, 14.1% and 15.4% for flavour liking, and 13.2% and 14% for texture/mouthfeel liking. In my tests, I’ve found 23% milk fat to be optimum for texture for homemade ice cream.
3. Reduce recrystallisation during storage
During storage, ice and lactose crystals grow and undergo recrystallisation. Recrystallisation is defined as “any change in number, size, shape… of crystals [during storage]” (17) and basically involves small crystals disappearing, large crystals growing, and crystals fusing together. This increase in crystal size eventually reaches a point where the ice cream develops coarse texture, at which point it has surpassed its shelf life. Ice creams containing a higher concentration of milk fat have a lower sensory perception of coarseness after storage (5 13). Fat globules mechanically obstruct the growth of ice crystals, thereby slowing the rate of recrystallisation and extending shelf life (16).
4. Melting rate
Increasing the fat level has been shown to reduce the rate at which ice cream melts during consumption (10 13 15).
5. Stabilise air bubbles
During dynamic freezing, where the ice cream mix is frozen in an ice cream machine whilst being agitated by the folding and mixing action of the rotating dasher and scrapper blades, the ice cream mix undergoes partial coalescence, where clumps and clusters of the fat globules form and build an internal fat structure or network by trapping air within the coalesced fat. These fat globule clusters are responsible for stabilising the air cells, thus preventing them from recombining and forming larger air bubbles (18 19 20). This results in the beneficial properties of dryness, smooth and creamy texture, and resistance to meltdown (21 22 23 24). Ice cream mixes with a high fat content are more susceptible to partial coalescence than those with a low fat content (25).
6. Summary
Milk fat has a significant effect on the perception of flavour. As a source of flavour, it contributes significantly to the buttery, creamy, and ‘rich’ flavour of ice cream. It is also the main carrier of added flavour, owing to more odour molecules dissolving in fat than in water. Fat also influences the rate of flavour release, the perceived flavour intensity, and the duration of flavour: generally speaking, a higher fat content leads to a slower release of flavour, lower flavour intensity, and a longer duration of flavour.
Milk fat contributes to the smooth and creamy texture of ice cream by lubricating the palate, thereby reducing the perception of coarseness due to large ice crystals. Fat globules also mechanically obstruct growth of ice crystals during storage, thereby slowing the rate of recrystallisation and extending shelf-life.
The partial coalescence of fat globules during dynamic freezing is responsible for stabilising air bubbles, resulting in the beneficial properties of dryness, smooth texture, and resistance to meltdown. Ice cream mixes with a high fat content are more susceptible to partial coalescence than those with a low fat content. Increasing the fat level in ice cream has also been shown to reduce the rate at which ice cream melts during consumption.
7. References
1. Bolliger, S., Goff, D., and Tharp, W., 2000. Correlation between colloidal properties of ice cream mix and ice cream. International Dairy Journal. 10: 303–309.
2. Goff, H. D., 1997. Colloidal aspects of ice cream. International Dairy Journal. 7: 363–373.
3. Granger, C., Leger, A., Barey, P., Langendorff, V., and Cansell, M., 2005. Influence of formulation on the structural networks in ice cream. International Dairy Journal. 15:255–262.
4. Goff, H. D., and Hartel R. W., 2013. Ice Cream. Seventh Edition. New York Springer.
5. Prindiville, E. A., Marshall, R. T., and Heymann, H., 1999. Effect of milk fat on the sensory properties of chocolate ice cream. Journal of Dairy Science. 82:1425-1432.
6. Maarse, H., and Van den Berg, F. Current Issues in Flavour Research. In: Piggott, J. R., and Paterson, A., eds. 1989. Distilled Beverage Flavour. ). Horwood Ellis
7. Hatchwell, L. C., Implication for fat on flavor. In: McGorrin R. J., & Leland, J. V. eds. 1996. Flavor-food interactions. Washington DC: American Chemical Society. vol. 633. pp. 14–23.
8. Li, Z., Marshall, R., Heymann, H., and Fernando, L., 1997. Effect of milk fat content on flavour perception of vanilla ice cream. Journal of Dairy Science. 80:3133-3141.
9. Lallemand, M., Giboreau, A., Rytz, A., and Colas, B., 1999. Extracting parameters from time-intensity curves using a trapezoid mode: the example of some sensory attributes of ice cream. Journal of Sensory Studies. 14(4), 387–399.
10. Frost, M. B., Heymann, H., Bredie, W. L. P., Diklsterhuis, G. B., and Martens, M., 2005. Sensory measurement of dynamic flavour intensity in ice cream with different fat levels and flavourings. Food Quality and Preference. 16. 305-314.
11. Bayarri, S., Taylor, A. J., and Hort, J., 2006. The role of fat in flavour perception: effect of partition and viscosity in model emulsions. Journal of Agricultural and Food Chemistry. 54.8862-8868.
12. Hyvonen, L, Linna, M., Tuorila, H., and Dijksterhuis, G., 2003. Perception of melting and flavour release of ice cream containing different types and contents of fat. Journal of Dairy Science. 86:1130-1138.
13. Stampanoni Koeferli, C.R., Piccinali, P., and Sigrist, S., 1996. The influence of fat, sugar and non-fat milk solids on selected taste, flavor and texture parameters of a vanilla ice-cream. Food Qual. Pref. 7: 69–79.
14. Hatchwell, L. C., 1994. Overcoming flavor challenges in low-fat frozn desserts. Food Technology. 48.98-102.
15. Guinard, J. X., Zoumas-Morse, C., Mori, L., Uatoni, B., Panyam, D., and Kilara, A., 1997. Sugar and fat effects on sensory properties of ice cream. Journal of Food Science. 62(5).
16. Donhowe, D. P., Hartel. R. W., and Bradley, R. L. Jr., 1991. Determination of ice crystal size and distribution in frozen desserts. Journal of Dairy Science. 74.3334-44.
17. Fennema, O. R., Powrie, W. D., and Marth, E. H., 1973. Low Temperature Preservation of Foods and living Matter. USA: Marcel Dekker, Inc.
18. Walstra, P., 1989. Principles of foam formation and stability. In Wilson, A. J., (Ed), Foams: Physics, Chemistry and Structure. Berlin: Springer.
19. Chang, Y., and Hartel, R. W., 2002. Measurement of air cell distributions in dairy foams. International Dairy Journal. 12:463-472.
20. Chang, Y., and Hartel, R. W., 2002. Development of air cells in a batch ice cream freezer. Journal of Food Engineering. 55, 71-78.
21. Eisner, M. D., Wildmoser, H., and Windhab, E, J., 2005. Air cell microstructuring in a high viscous ice cream matrix. Colloids and Surfaces A: Physicochemical and Engineering Aspects. 263(1)
22. Lin, P. M., and Leeder, J. G., 1974. Mechanisms of emulsifier action in an ice cream system. Journal of Food Science. 39. 108-111.
23. Buchheim, W., Barfod, N. M., and Krog, N., 1985. Relation between microstructure, destabilization phenomena and rheological properties of shippable emulsions. Food Microstructure. 4. 221-232.
24. Berger, K. G., 1990. Ice cream. In Larson, K., and Friberg, S., Food Emulsions, 2nd ed. New York: Marcel Dekker Inc.
25. Hinrichs J., and Kessler, H., 1997. Fat content of milk and cream and effects on fat globule stability. Journal of Food Science. 62: 992-5.
26. McCandlish, A.M., Kilara, A., Macneil, J. H, and Tharp, B. W., 1992. The effects of fat on the sensory attributes of ice cream. Institute of Food Technologists Annual Meeting, Anaheim, CA. Book of Abstracts, p. 10.
hi! I am curious to why you landed at a much higher fat ratio of 23% for domestic machines while the research sited shows that optimal fat ratio at around in the 10+% range.
Is this purely due to the freezing capabilities of commercial ice cream machine? I have the opportunity to use a Bravo machine recently and my high 20% fat recipe (which works wonderfully in my domestic freezer bowl), fails to have any overrun in the commercial churner.
Would love to hear your thoughts on this. 🙂
Ruben, great website. If you’re adding a flavor ingredient, say lemon juice to make lemon ice cream, would you increase the milkfat percentage to compensate for the added water in the lemon juice?
i really like your post role fat ice cream. keep posting.
Can anyone tell me how to reduce the fat content of 14% fat ice cream mix from 14% to 10%? How much 3.5% whole milk do I add to one gallon of 14% fat ice cream mix to result in a 10% ice cream mix? Thanks.
ethansimmons111@yahoo.com
Hi Ethan,
Thanks for getting in touch. To calculate this, I will need to know the total weight, in grams, of your one gallon mix, as well as the weight in grams of all of the other ingredients, bar milk and cream, that you have in your recipe. I will also need to know the fat percentage of the cream that you are using. Once I have this information, I’ll do my best to work out how much milk and cream you need for a 10% butterfat mix.
All the best,
Ruben
I have no idea. I’m considering opening up an Ice Cream Parlour here, and the only local source for ice cream mix has 14% and 16% mixes. I want to use 10% mix, and was hoping someone more knowledgeable could tell me how much 3.5% whole milk to add to one gallon of 14% mix, or 16% mix, to end up with an end product of 10% ice cream mix, Thanks.
It’s not possible to say how much milk and cream you will need without the info I asked for previously if you want to match the recipe that your local source of ice cream mix produces. I can work with you on a consultation basis if you would like me to put a recipe together for you, taking account of the ingredients that you would like to use and the fat content of your mix.
Hope that helps.
Ruben
Hi Ruben,
Can you help me, how to calculate the fat % in an icecream bulk.
Regards,
Mihir
Can we reduce dairy fat. Like using full fat milk with no CREAM and rather using coconut oil or olive oil. how it would affect the texture. And in that case how the spread sheet will work
Yes you can reduce a portion of the dairy fat and replace it with coconut oil, I don’t know how much coconut oil you would be able to use. Coconut oil ha a different melting profile to dairy fat so your ice cream will likely be harder. Coconut oil can also give quite a negative cheap coconut oil flavour if too much is used. It can also leave a cloying sensation in the mouth. You won’t be able to use the spreadsheet for this but can calculate the amount needed manually.
I hope that helps.
Ruben
Hi,
I really liked your post! It is an easy scientific read!
However I still have a question.
Basically you say the more fat results in less flavour, due to reduction of volatility.
But why does one say that fat is a flavour carrier? Just because the molecules dissolve better in fat? But then again they are released less well…
Hi Ruben
Thanks for your amazing posting. I really want to run my own ice cream business one day and your researches and your ice cream recipes are incredibly helpful to learn how to make artisanal ice cream. Appreciate it. I have a question about “optimum range of fat content” on post-heating mixture.
When I tried your vanilla ice cream recipe, the resulting ice cream was so good but I felt a little sweet for my taste. So for the next batch, I might try to lower sugar% to 15% but don’t want to sacrifice creamy texture. To keep total solids content around 54%, I might increase ‘desire mix fat(%)’ from 20.1 to 20.8, which would give me 23.9% of fat content, a bit higher than your 23.0%. Have you ever tried this fat content before?
Thanks.
Best,
Sungjoon
Hi I am a Icecream manufacturers in Pune India .on 600 liter batch I am using 400 liter milk (6.5 fat) 38 KG milk powder .100 kg sugar .60 kg cream (60 percent fat) 2 .2 kg stabilizer .5 kg lequid glucose.With all these indigent I am not getting 10 percent fat let me know how can i increase a fat level
Hi Ruben!
I am delighted to read about ice cream in your blog! I love that you rely on scientific data. Congratulations!
I have a question about the fat content in your recipes… is there a reason why you don’t consider the fat in the yolks?
Hi there Barbara!
Thanks for getting in touch. Yes the reason that I don’t consider the fat content of the egg yolks in my calculations is that the formulas in the book Ice Cream, by Professors Goff and Hartel, on which my spreadsheet is based, also do not consider it. My guess is that perhaps the fat in the yolks doesn’t provide the same beneficial effects in ice cream as the fat in milk and cream. I haven’t done any research into the fats in egg yolks so I don’t know for sure.
Hope that response helps. Let me know if you have any other questions.
All the best,
Ruben
Hi Ruben,
Another great post. Thank you.
But I was wondering if you have any experience with fats with significant different solid fat index values?
With a trial I did with different fats for a vegan recipe (only changed the fat type) I had huge difference in cold mouth feel, icy crystal size and overrun.
I used a homogeniser to have a proper fat dispersion. So particle size of the fat should not be an issue.
Kind regards,
Bouke
Hey Bouke!
Researching alternative fats to dairy fat is actually the next area I want to start researching as I want to develop a dairy recipe. I’ll post my research and a recipe on the blog once I finish, although this may take me a while! Which fats have you tried?
All the best,
Ruben
Hi
Have you experimented with substituting some cocoa butter? I read a post about it (https://www.giapo.com/why-cocoa-butter/) and was intrigued. After trying it out for a few batches, I actually do agree that adding some cocoa butter does give a cleaner flavor, although I’m not discounting the placebo effect.
Anyway, if you’ve tried it out, I’ll be really interested to hear your thoughts on it and what your preferred substitution ratio is.
Cheers!
Hi Zachary,
I have actually substituted milk fat partly with cocoa butter and it is possible to make a good tasting ice cream but you always need to keep in mind that cocoa butter is a hard fat especially in comparison to other common fats for ice cream. So you need to compensate with a little bit of extra lecithin or other emulsifiers. But I am most experienced with lecithin as we do a lot of trials with that and works very well for us.
And the melting point of cocoa butter is relatively low around 28 degrees Celsius. This can make processing a bit tricky. Homogenisation needs to be done to reduce the size of the fat particles. It depends on the machine you use for that but I found the optimum of 230 bars pressure with a flow rate of 20l/h to work the best for us. The temperature of the mix needs to be maintained above 40 degrees Celsius to prevent solidification of the cocoa fat.
If you have questions about cocoa feel free to ask. I work with it daily.
Kind regards,
Bouke
🙂
Hi there Zachary!
Thanks for getting in touch. I haven’t yet experimented with cocoa butter but it is something that I want to research and test when I get the time. The article you linked sounds interesting; it would be interesting to see whether cocoa butter holds onto more or fewer flavour molecules than milk fat, which would affect the intensity and release of flavour. Are you using cocoa butter in a vegan ice cream recipe?
All the best,
Ruben
Hi Ruben,
We used 2 types produced by our own factory, a coconut oil and Partially hydrogenated palm kernel oil.
The Partially hydrogenated palm kernel oil had the highest solid fat index and ice made with that fat compared to the others made in similair conditions produced bigger ice crystals and is more watery in flavour.
Kind regards,
Bouke
Hey Bouke,
The bigger ice crystals produced by the partially hydrogenated palm kernel oil sounds very interesting. Do you guys run your own ice cream business?
All the best,
Ruben
Hi Ruben,
No, the plant where I work is a factory that makes cocoa products. And we help our customers with questions they have about cocoa.
We have a small scale ice cream factory in the lab. That I can play around with. Therefor I have done trials with cocoa butter in ice. And the recipes I make here are more tailor made to specific products. The fats for vegan ice creams we get from another branch located in the UK. They are specialised in fats. But lack the equipment so I help them out when they have questions about ice.
Kind regads,
Bouke