How ice cream is made? Private2 weeks ago - Automobiles - Ban Lŭng - 7 views
With longer, warmer days approaching, the sounds of summer are finally here: the drone of lawn mowers, the thwack of leather on willow and the incessant screams of young children demanding ice cream. To be fair though, there are plenty of adults who can’t pass a gelato shop, park cafe or ice cream van without succumbing to temptation either. There is just something so satisfying and refreshing about an ice cream on a hot day, to stay with a refrigerator, or you can call it refrigerator-freezer.
Ice cream has been around a long time. Some sources mention ice cream-like foods originating in Persia in about 550BC. Some even believe that the Roman Emperor Nero had snow collected from the mountains and mixed with honey and wine to make sorbet. These days we have hundreds of different types of ice cream, from the usual ice cream van favourites to gourmet gelatos and experimental savoury flavours.
On the face of it, the main ingredients of ice cream as we know it are really simple using a cooler: milk, cream and sugar. But just mixing these with some flavouring and putting it in the ice cream freezer is not going to give you a good result. The secret to great ice cream lies in how the mixture is mixed, how quickly it’s frozen and some key extra ingredients that change things like viscosity and freezing point – all important for the right texture and taste.‘To get the right creaminess and stability, the air bubbles in ice cream need to be about 20 µm in size, and as uniform as possible,’ continues Brent. ‘An air bubble that size in water would dissolve quickly – perhaps in a couple of minutes – because air is quite soluble in water. A combination of natural foaming agents (proteins again), the aggregated fat droplets, plus freezing as fast as possible to increase viscosity, helps to trap the bubbles at that small size.’You can use one type of freezer- Curverd Glass Type Ice Cream Chest Freezer.
The rate of freezing has a big effect on the finished ice cream because it affects how large the ice crystals can grow. Large crystals can cause the end product to taste watery or icy, with a coarse, rough texture. The secret to great ice cream is to keep the crystals small. ‘There are two types of freezing,’ explains Ruben, ‘dynamic freezing, where the mixture is moved around at about -6˚C, usually in the ice-cream mixer, and static freezing, which is much colder and doesn’t involve any stirring. Ice crystals will grow in the dynamic freezing stage, but not during static freezing. So, you want to get your ice cream out of the machine as quickly as you can and into a cold chest or blast ice cream freezer at about -18˚C.’
‘If your freezer takes eight hours to get the mixture down to -18˚C then you are going to have more ice crystals in it than if you achieve that in two or four hours,’ Ruben says.
The walls of an ice-cream maker are pretty cold, about -32˚C with a fridge, but the mixture is moving all the time, so it never reaches this temperature. Of course, colder substances, which you’d usually find in the lab and not the kitchen, have also been tried, such as liquid nitrogen. ‘That’s terrific theatre!’ says Ruben. ‘And it creates an incredibly creamy product. With liquid nitrogen you only need one or two minutes in the ice machine before you can transfer to the deep freeze. The rate of crystal nucleation – the birth of ice crystals – is much faster, so there are more of them, but they are much smaller.’