New Bacteria Test Could Improve Quality Of Fruit And Vegetable Juice

Collaborating with scientists in the United States and from around the world, Mengshi Lin, assistant professor of food science in the College of Agriculture, Food and Natural Resources, has successfully used a new approach combining DNA sequencing technique with mid-infrared spectroscopy to rapidly and accurately identify Alicyclobacillus, a common bacterium found in apple, carrot, tomato, orange and pear juices, tropical fruit juices and juice blends. The bacterium won't cause human sickness, but it affects flavor and results in spoilage.

Currently, a number of different testing methods are utilized, some of which yield false negative results. This has complicated international trade. Japan, along with other developed countries, has a zero tolerance for this bacterium in imported juices, Lin said.

He said identification is a challenge because spoilage can be difficult to distinguish visibly until test results are confirmed or after juice products have been opened and tasted by consumers. In addition to agitating taste buds, the latter can affect consumer confidence.

Lin's technique is significant because it identifies the organism quickly - in a matter of hours, unlike traditional culturing methods, which are time consuming and require five to seven days to process. Lin said that testing time is critical for juice processing companies, which monitor for the bacteria during the processing and final product stage. He said the DNA technique in combination with infrared spectroscopy technique won't cause long delays in production.

"This combination will be the best way to quickly and accurately detect and identify the bacteria," said Lin, who worked with researchers from Washington State University and Hashemite University in Jordan, to develop the technique. "If processors find the bacteria, they can go back quickly and find the affected products."

Lin and his research team have tested the technique and published the results in a study, "Phylogenetic and spectroscopic analysis of Alicyclobacillus isolates by 16S rDNA sequencing and mid-infrared spectroscopy," which has been published in Sensing and Instrumentation for Food Quality and Safety.