How many germs are on your salad?
Scientists create a cheap device to detect bacteria in food
Ivan Sychev, Geektimes
A group of scientists from the University of Massachusetts at Amherst has created a fast and inexpensive method for detecting bacteria in food and drinks. The developers believe that it will be in demand by people who eat raw food – fresh fruits and vegetables, as well as humanitarian organizations working in the field after natural disasters.
"Most people around the world cook vegetables before eating, but in the US a lot of people prefer to eat them raw. This gave us the idea of creating a quick test that can be carried out at home," the developers said in an article published on the website of the University of Massachusetts at Amherst (UMass Amherst Food Scientists Developing a New, Low–Cost Tool for Detecting Bacteria in Food and Water). The problem is also relevant because today there are bacteria that are resistant to all popular antibiotics.
Usually, a seeding method is used to count the number of bacteria, which takes about two days. There are faster, but less reliable ways. The new chip interacts only with bacteria, but not with sugars, fats, proteins or dirt in food.
The new device uses a two-stage method of detecting bacteria: optical and chemical testing.
The designed chip is able to find bacteria both on the surface of solid food – for example, on spinach leaves, and in liquids like apple juice. The optical method involves the detection of 3-mercaptophenylboronic acid, which binds to any bacteria. The components of the food are removed using a buffer with a high pH, leaving the bacteria to be quantified using a microscope for a smartphone and an application.
The sensitivity of the method makes it possible to detect even 100 bacteria per 1 milliliter, while other "quick" solutions are able to find bacteria with an amount of at least 10,000 per 1 ml.
The chemical method uses surface-enhanced Raman spectroscopy (SERS) – technology that helps to identify cancer cells among a large number of healthy ones and distinguish fake paintings from real ones. The technology is based on the analysis of laser beams reflected from the material with a variable wavelength.
According to scientists, already last summer they tested an optical method for detecting bacteria for possible home use with a microscope for a smartphone, which costs about $ 30. The smartphone app was developed by a student. The development is in the process of patenting.
The scientific article was published in the journal Food Microbiology.
Portal "Eternal youth" http://vechnayamolodost.ru