Tuesday, January 22, 2008

Hazardous Home-made Ice Cream

We’ve probably all eaten and enjoyed home-made ice cream at some time in our lives. It can be great fun for kids to help Mum make it during the summer holidays.

During the recent summer holiday (Southern Hemisphere), my neighbour gave me a recipe for making ice cream. It seemed simple enough – just combining eggs and cream, vanilla and sugar and then freezing it, stirring at intervals. “The children just love it”. There was no mention of pasteurization, which made me uncomfortable.

I looked for “Ice cream home made” on Google and found many recipes, some of which used eggs. Some included heating steps, some didn’t. This is worrying.

Eggs can potentially be infected with Salmonella during formation in the hen. External contamination can also occur, which may be transferred to the egg contents when the shell is cracked. The egg industry has procedures in place to minimize these risks and commercial egg pulp is pasteurized. This is a fairly delicate balance between providing sufficient heat to kill pathogenic bacteria and not causing the egg proteins to denature.

If you are going to make ice cream at home this summer, I recommend that you either use a recipe that does not call for eggs, or that you use a process that heats the eggs. A typical recipe can be found at:
http://www.cooks.com/rec/doc/0,1613,150189-248198,00.html
where the following instruction is given: “In heavy 3 quart saucepan with wire whisk, combine sugar, flour and salt. Beat in milk and eggs until well blended. Cook over medium low heat, stirring frequently, until mixture thickens and coats spoon, about 30 to 45 minutes. (Do not boil or mixture will curdle.) Cover surface with plastic wrap; cool completely, about 3 hours”.

The temperature of the egg mix needs to get high enough to kill Salmonella bacteria if they are present. This can be achieved by heating the mix to 80C and holding it for 15 seconds.

No comments:

Post a Comment

Comments on this blog are welcome, as are questions and suggestions for further articles. Comments are moderated to reduce the incidence of spam. If your comment includes a link to a commercial site, it will normally be rejected.