Introduction
Vegan ice cream might be an alternative choice for people who don't consume dairy products due to intolerance to lactose, which is a natural sugar found in dairy products. The composition of vegan ice cream is trying its best to mimic that of conventional dairy ice cream to have the creamy and rich texture, however, the struggle there is to find the ideal planted fat to facilitate partial coalescence.
Partial Coalescence
Partial Coalescence is easier to facilitate under dairy spectrum because the milk protein casein itself has much stronger emulsifying properties whilst water part from vegan ones lack of this as stigma. Ice cream is a multiphase structure that consists of ice crystals, air bubbles, fat globules and the very concentrated unfrozen serum coming from sweeteners. From the start of composing an ice cream, the application of protein(emulsifier), such as egg yolk for example, to the time when aged ice cream mix is agitated in the machine during dynamic freezing, it is for the purpose of promoting partial coalescence: the protein is to emulsify the fat globules with other solids such as sweeteners, food fibre as well as water, ensuring that the fat globules is not going to be way too stablised during aging process and fail to the multiphase with other components when agitated.
As ice cream mix being churned by the rotated scraper blade in the machine, those fat globules being emulsified with other components will start destabilising and form clumps after collision with each other, combining together as a cluster and this phenomenon is so called partial coalescence. Partial coalescence is very important because it forms a solid structure to combine, kind of surrounding the partially-coalescenced fat clumps with air cells (from churning), ice crystals (from water after temperature drops to that expected ice cream mix's freezing point) and the concentrated unfrozen serum (from sweeteners and other minor minerals, vitamins and enzymes of milk). Partial coalescence ensures couples of standards to be qualified as a decent ice cream - the melting speed, shape retention and neatness. Ice cream that has achieved ideal partial coalescence will have slow melting speed, good shape retention as well as dry and neat surface.
Picture shows how partial coalescence works out after dynamic freezing.
Vegan ice cream is no other than dairy ice cream when it comes to partial coalescence although the dairy is excluded from the composition. The point is when there is lack of dairy whose protein and fat profile is great, then how to facilitate the phenomenon when making vegan one?
The figure shows some common planted fats used in commercial vegan ice cream production.
Introduction of planted fat
Planted fats are used when making vegan ice cream and every planted fat has its own lipid profile, which directly affects the ratio of partial coalescence when it comes to ice cream production. Fat is a generic name as part of the many complicated compounds, also known as lipid. The lipid has different molecules such as triacylglycerols, diacylglycerols, monoacylglycerols, free fatty acids, sterols, and phospholipids. Triacylglycerols is the most common lipid found in food and it is usually this type of oil that refers to the fat we call and see in nutrition label. Triacylglycerols can be solid or liquid form based on its constituent of fatty acids. If it is rich in saturated fat, like coconut oil, it becomes solid at room temperature (20-25°C), whilst if it is rich in unsaturated fat, like sunflower oil or olive oil, it is liquid at room temperature (20-25°C).
Blended planted fat
Each fat/oil has different solid : liquid fat ratio , such as milk has 70% solid fat at 4°C to 5°C, hence final blend in ice cream mix will directly affect how partial coalescence works out - it is essential that an ice cream mix contains an optimum ratio of solid : liquid fat at 4°C to 5°C after aging. In my test batch experiments, replacing milk fat by using single planted fat resulted in terrible partial coalescence - be it either insufficiency or redundance - making the ice cream have terrible characteristics such as wet surface, brick-like hard to scoop after freezing, icy, multiphase separation such as greasy mouthfeel whilst the one made with blended planted fats has troubleshot those problems that becomes dry and neat when extracted, smooth and creamy as well as easy to scoop after freezing. Hence, a blend of planted fats are recommended.
Melting profile of fats
Each fat has its melting point based on their constituent profile. Edible fats have their own mixture of triacylglycerol molecules and each have their melting point. Rather than melting at a distinct temperature, ice cream is preferably consumed within a longer period of time. Milk fat for example melts ranging from -40°C to 40°C as it has a broad range of fat molecules, each having their own melting point, whilst coconut oil and palm kernel oil have a relatively distinct melting point at 24°C and 27°C respectively compared to milk fat, and that's why dairy ice cream tends to melt slower than vegan ice cream given that other factors in the composition remain equal. Regarding to vegan ice cream, like dairy one, it should not melt too fast nor melt too slow neither, hence choosing fats when producing vegan ice cream should take balance of melting point into consideration - trial and error is needed.
Limitations
Ice cream flavour - whether it is dairy one or vegan one - should be delivered naturally and neutrally without any weird aftertaste from base flavour. Whilst dairy ice cream made with milk has a natural milky taste that almost tastes nothing other than milk, which is ideal for making wide range of ice cream flavour, vegan one is notoriously known to be having weird base flavour in the industry, which is a big issue that has to be sorted properly too.
Summary
Partial coalescence is the phenomenon that emulsified fat globules starts destabilising and partially grouping as a cluster to surround other components like air cells and ice crystals. This process is important regarding to both vegan and dairy ice cream. Vegan ice cream is a mimic but it is no other than dairy one except the usage of dairy as the biggest difference. It is recommended to use blended planted fats as different planted fats have their own lipid profile that some can be solid at room temperature whilst some are not, which will directly affect the scoopability of the ice cream as well as the ratio of partial coalescence. Planted fats also have their own melting point that will affect the consumption experience. Single planted fat with overly high or low melting point will either be having greasy mouthfeel as it melts too fast or hard-rock texture as it melts too slow.
Comments