~Roscommon young scientists test best before dates~
Shane Maher , Thomas Cullen and James Finnerty, all 16-years-old and transition year students at CBS Roscommon, decided to look at how fresh is “fresh” milk as part of a BT Young Scientists project.
“We were trying to find which was the freshest milk in our area by carrying out four different tests,” explained James.
The main one was to measure how much lactic acid was in the milk, says Thomas. “Lactic acid is what makes the milk turn sour” he explained. The bacteria release an enzyme that breaks up lactose in the milk and lactic acid forms. The more acid, the quicker the spoiling.
They discovered that of the seven brands they tested regularly over a six week time period, Connacht Gold was consistently the “freshest” on the basis of lactic acid levels.
It is a challenge keeping bacterial levels low, said Shane. Milk from the cow is collected at 38 degrees and has to be cooled quickly to at least seven degrees or less.
“Once pasteurised the milk is sterile, but things don’t stay that way for long” Thomas said. It moves through different sets of hands, from farmer to processor and processor to shops and shops to consumer so there are lots of opportunities for it to warm up slightly, they say.
The only way to slow spoiling is to keep the milk at a low temperature for as long as possible – and they advise that a fridge is obviously best, but warn against keeping it in the door shelves as this is the warmest part of the fridge.
Speaking about the project, the students’ Agri Science teacher, Louise Gallagher said “it was a fantastic experience at the Young Scientists exhibition. Shane, Thomas and James put a lot of effort and technical research into their project and were delighted to see coverage in some national media”.