Buy your milk in a carton and forget the glass and plastic containers. So suggest two Esat Telecom Young Scientists exhibitors at the RDS who found milk stayed fresher in the familiar paper cartons.
"We decided to see which kind of container was best at keeping milk fresh," explained Sarah Kelly (14), who completed her project with Lauren Fox (13). Both are second-year students at Loreto College, St Stephen's Green.
They carried out tests using facilities at UCD's Department of Industrial Microbiology. They bought milk supplies immediately after pasteurisation in each of the container types and began assessing the gradual deterioration of milk quality over time.
Naturally occurring bacteria cause milk to sour, they explained, so much of their work focused on bacterial contamination. They used a Resazurin Test, a dye-based measure of bacterial activity. They also measured acidity levels (bacteria make milk more acid) and prepared bacterial cultures. Visual assessment of the milk was also used.
The cartons won hands down, Sarah said. The paper is coated with a special plastic which retards bacterial growth and the exclusion of light also helps to keep the bacteria in check. Surprisingly the tests indicated that milk soured more quickly in the glass than the plastic containers.
Think twice about enjoying rhubarb tart with your glass of fresh milk, warn Ashling McNeill, Katie Doyle and Karen Duffy, all 13-year-old students at Malahide Community School.
They studied concentrations of naturally-occurring ethane-dioic acid in a variety of food products containing rhubarb.
The substance is classed as a weak poison, explained Katie, although large quantities can be consumed without any harm. They used titration and measurement of chemical precipitates to determine ethane-dioic acid levels in rhubarb tart, rhubarb jam and in twin-pot and single-pot yoghurts which contained rhubarb.
The twin-pot yoghurt had the most and the jam the least, according to their work, which required 300 hours' effort by the three.
