Ice Cream Curdling While Churning

Our answer

Nigella's Cheesecake Ice Cream (from NIGELLA SUMMER) has cream cheese added to a traditional custard base, to give a slightly sharp cheesecake-flavoured ice cream. It is very unusual for a custard mixture to curdle during churning and it is possible that the problem ocurred when the cream was added to the custard mixture.

If the cream had been whipped until it was almost firm then it may not have mixed quite smoothly with the custard and further churning of whipped cream can cause it to curdle as the fat molecules will start to clump together. Only whip the cream until it is just holding its shape, before adding it to the custard. Also if the cream is very cold and added to slightly warm/room temperature custard then this can shock the fat molecules in the custard and cause the mixture to curdle a little, though this is quite rare. It may help to chill the custard before adding the cream and then churning. Finally, the cream cheese should be a type similar to Philadelphia, with a fat content of around 33%. In the UK there is a higher fat cream cheese, with a fat content of around 55% (though it is less common in supermarkets now), and there is a slight possibility that using this, along with double cream, could have pushed the fat content of the mixture to a stage where it can curdle more easily if it is churned for any length of time.