| 2006 |
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YEAR BOOK |
Kinsale Community School, Co Cork
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The development and evaluation of a food spoilage indicator
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I wanted it to be as easy as possible for the consumer to use, so I decided to develop a colour-based indicator to show if a perishable product was fresh, deteriorating or spoiled. It would be part of the packaging of the product and should not add significantly to the cost of the item.
The system I developed is based on the life cycle of a harmless bacteria, Lactococcus lactis. I commenced my experimentation using test units containing a known quantity of the L. lactis bacteria and a special nutrient solution. Included in the sealed unit is a pH indicator that is sensitive to acid. As L. lactis consumes the nutrient it produces lactic acid which begins to change the colour of the indicator. As the packaged food and the biological indicator are exposed to higher temperatures over time the bacteria multiply at a faster rate and produce more acid. This increased activity causes the colour to change more quickly and mimics the growth rate of bacteria in the host food as it spoils.
I determined the growth of my L. lactis cultures over time and temperature and then determined the appropriate concentrations of L. lactis and nutrient to achieve a particular colour change while replicating the bacterial growth expected during food spoilage.
I ran a series of tests comparing the growth of a harmful bacteria in food, Escherichia coli (E-coli) with the Lactococcus lactis in my samples. I was able to use the colour change associated with the growth of L. lactis to indicate a critical stage at which levels of E-coli might rise to a dangerous level. I was not allowed to use actual E-coli in the development of my indicator given that it is a dangerous pathogen and requires special laboratories and equipment. However as its growth rates at different temperatures are well known, I was able to fine tune my design theoretically.
My results were very consistent and repeatable and I demonstrated that the development of the spoilage indicator was both feasible and effective.
Aisling Judge entered the Junior Biology Section of the BT Young Scientist &Technology Exhibition in January 2006. She was awarded the top prize of Young Scientist of the Year 2006 . She was awarded a special prize by Science Foundation Ireland for her innovative combination of biology and technology. Aisling is a student in Kinsale Community School, Co Cork and her teacher is Ms Catriona Barrett.
| This article was sponsored by Science Foundation Ireland. |
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