Welcome to our Christmas dinner special. We’ll be talking about the food science of traditional Christmas dinner cuisine. Have you ever thought about the science behind your Christmas dinner? If the answer is yes, make sure you follow us because we will be posting a new article every Friday and Monday over the next two weeks, in preparation for Christmas, on a dish that’s commonly served as part of traditional Christmas dinner.
The Christmas pudding goes back all the way to medieval England, when it was known as ‘plum pudding’. There are no plums in the pudding but the word ‘plum’ was used as a term for raisins in the pre-Victorian era. There was a custom that pudding should be “made with 13 ingredients to represent Jesus and His Disciples and that every member of the family should take turns to stir the pudding with a wooden spoon from east to west, in honour of the Wise Men”. It’s traditionally made with a mixture of dried mixed fruits, alcohol, suet (or more recently butter) eggs, flour and fragrant spices, and is steamed for a long time.
Butter or Suet?
Most recipes you’ll find, deviate from the norm and use butter in the pudding instead of suet. However, suet was traditionally used because of its high boiling point. Suet is a white, solid fat which is found around the kidneys of cows and sheep. Suet has a higher boiling point than butter, which means it does not melt until the batter has cooked and has begun to set, then the suet begins to melt creating tiny holes which make the pudding lighter in texture. Butter melts at a significantly lower boiling point which causes the pudding to be heavier and greasier than when using suet. A vegetarian alternative to suet is vegetable shortening. This is because it has a similar boiling point to suet in the steamed pudding, but it can change the taste.
What’s in a flambé?
One of the most important Christmas traditions is the lighting of the Christmas pudding, also known as a flambé. When warm brandy is lit over the pudding, it burns and evaporates the water from the brandy, this also prevents it from overheating and getting burnt. The blue flame is created by the reaction of ethanol (the alcohol in brandy) vapour and oxygen from the air. The flame doesn’t reach the pudding, as it is the ethanol vapour that is burning, not the pudding itself.
A 50-year-old Christmas pudding?!
In 2017, scientists claimed that is was safe to consume a 48-year-old Christmas pudding. Scientists at the University of Nottingham spoke to a popular food programme about this aged Christmas pudding. Dr Tania Perehinec, tested the pudding rigorously to test whether any bacteria such as E. coli or Salmonella grew. The tests showed that yeasts and/or moulds were absent from the pudding, and the laboratory tests showed that no bacteria grew in the pudding, surprisingly. This is because bacteria cannot survive in a dry Christmas pudding. Although it may appear to be moist, the water content is bound to the other food components in the pudding, making them unavailable to bacteria to react with, this is also known as the water activity (Aw) in food.
In addition to this, the pudding was boiled vigorously for several hours before it was stored. The high heat from the boiling denatured all the bacteria in the cooking process. The bacteria couldn’t survive such high temperatures. The pudding was also sealed from air, in a cool place which also helped protect it from the elements and/or conditions that could help bacteria grow.
So, now you’ve learned a lot about Christmas Pudding, we have come to the end of our Christmas Dinner series, we hope you’ve enjoyed learning about the food science behind each Christmas Dinner favourite. You can read our other Christmas dinner articles on turkey, nut roast and winter vegetables by heading over to https://www.ifst.org/news. We look forward to reading your comments on our Christmas dinner articles. Tweet us @IFSTNews or tag us in you Instagram posts and stories @institute_of_food_science with your opinions and don’t forget to share this article with your friends and family.