How hard is coating?
“The best things in life are simple”. Whoever originally made this uplifting statement definitely wasn’t talking about ice cream coatings. Because consistently achieving that rewarding sensation of chocolaty crunch as you bite through to soft ice cream beneath, the cocoa flavour deliciously offsetting the ice cream’s sweetness, is anything but simple.
The truth is that, for every TV ad that depicts a group of happy, relaxed consumers enjoying the sensations of chocolate-coated ice creams on a hot summer’s day, there’s a stressed and frustrated production manager doing all he or she can to overcome constant challenges of managing viscosity, different surface temperatures and more besides.
It doesn’t have to be that way, however. In fact, achieving success with ice cream coatings is largely about using the right emulsifiers in the right way. Unfortunately, there’s not much in the literature for manufacturers to lean on, even when they do recognize emulsifiers as a solution, so I’ll primarily draw upon Palsgaard’s internal know-how to offer advice that is likely to be of use.
In more than 35 years spent helping customers to smooth away their frustrations, we’ve seen just about every combination of challenges. And we’ve managed to refine our own emulsifiers and techniques to a point where there’s now an effective toolbox that can overcome each challenge, enabling production people to smile along with their product’s consumers.
The beauty of coatings
Ice cream coatings are typically thin layers manufactured from inexpensive fats such as coconut oil or hydrogenated palm kernel. Total fat content is often above 60% so as to achieve a sufficiently thin layer and short crystallization time.
From stick ice creams to Eskimo bars, there are many products that can benefit from coating. A typical confectionery coating protects the filling, keeping it inside the praline and ensuring it won’t dry out. Those enjoying the product can hold it with a minimum of mess, and when eaten, a good coating gives a pleasurable and varied experience, both in terms of mouth-feel and flavour release. Much of the credit for this must be given to the special properties of confectionery fats such as cocoa butter, which is uniquely hard and brittle below 30°C (86°F), yet which melts in the mouth at 35°C (95°F).
The dark side
What makes working with coatings so difficult? For one thing, ice cream is best produced when it’s cold, while chocolate is easiest to work with when it’s warm. For another, chocolate has almost no water content while ice cream is mostly water. So bringing the two of them together is hardly a match made in heaven.
But there are more challenges, and the list centres around the interaction between filling and coating, with problems showing up, for the most part, not during production but in the days and months that follow:
• The coating speed required is far faster than that of other, non-ice cream applications.
• Moisture will always migrate from the ice cream into the chocolate.
• Cracking may result if the chocolate is, for example, not sufficiently plastic.
• Fat can migrate from the filling to the chocolate coating, causing a greyish layer known as ‘bloom’.
• Alcohol content in the filling may cause instability or even leaking.
I’ll focus on the first three, most important issues for this article.
