On a summer's day, many of us love nothing better than an ice cream. Not only does it help to cool us down, it is also a complex blend of sugar and fat that has been optimised for maximum liking. There are a number of aspects to ice cream that influence how much we like it.
The texture of the ice cream, the size of ice crystals, and the type of fats used, all affect how it melts in our mouths, and this has a large impact on our liking of ice cream.
This melting-in-the-mouth is also the same reason we like chocolate so much: cocoa butter, the main fat in chocolate, melts at 34 degrees - mouth temperature - which gives us a nice perception on our tongue. When other types of fats are used, sometimes they can leave us with a 'mouth coating' - a thin layer of fat on our tongue, and these are not as pleasant to eat.
However, cocoa butter can be expensive, and food scientists often use other fats, with different melting temperatures, in combination, in order to get them to work together to give as close to the ideal texture, while also being affordable.
For ice cream, the ideal texture will feel thick and creamy on our tongues, and will melt in our mouth without feeling watery, but also without leaving a coated feeling.
Flavour is a multisensory perception, and relates to how we perceive taste and smell, and the other senses, all combined in the brain. We need smell to be able to fully perceive flavour. If you pinch your nose tightly, and pop some ice cream into your mouth, you will only be able to taste the five 'basic' tastes - sweet, sour, salty, bitter, and savoury/umami. But you won't be able to tell if that ice cream is vanilla, or strawberry.
Release your nose, and once the odour molecules start to circulate, you can recognise the flavour! Flavour can also be influenced by many other things, such as the colour of the food and cutlery - using a heavier spoon gives a perception of more creaminess!
Making a "99", by adding a chocolate flake, brings in a contrast of textures, which also heightens the eating pleasure. However, a downside is that contrasting colours and textures can encourage us to eat more. Studies have shown that we eat more from buffets when there are more foods on offer - the same with a simple bowl of sweets if they are multicoloured!
These tricks can also be used to your advantage: have a small, plain ice cream without a flake, use a heavy spoon, and not only will you keep the calories to a minimum, but it may also help you to feel satisfied compared with having the same size portion with inclusions and toppings.
If you really want another texture in there, try summer fruits as a healthier option!
Dr Emma Feeney is a sensory scientist with the UCD Institute of Food and Health.