WSU Cougar Head Logo Washington State University
WSU Insider
News and Information for Faculty, Staff, and the WSU Community

Sour grapes

Although the multicolored Asian lady beetle has been found to cause taste and smell differences in wine and grape juice, the problem has yet to reach Washington. 

“The lady bug problem is bigger on the east coast,” said Carolyn Ross, assistant professor of food science. “Here we don’t have a problem.”

Ross, along with five other researchers, has studied the effects of the Asian lady beetle on Concord grape juice.

“My goal is to help the industry,” Ross said. “The research can help if they need to determine quality standards.”

Previously, wine had to be recalled in southern Ontario because of lady bug taint, characterized by a green pepper-like odor and taste in white wine, and a peanut smell in red wine, Ross said.

The beetles, which are forced to relocate when the corn silage they reside in is harvested, nestle in the grapes and are processed with them. The bugs then release a substance that causes the unpleasant odor and taste.

Ross began her work based on wine research that found that, even at one bug per liter, people could tell the wine was tainted.

“The results are remarkably similar for how strong Concord grape juice is,” Ross said. “I didn’t think it would take so few (beetles).”

Ross found that 1.8 bugs per liter create a noticeable smell difference in grape juice.

The pepper and peanut smells associated with tainted wine have not been found in tainted grape juice, Ross said. Instead, grape juice tends to have a dirty or musty smell.

Although Ross has determined the number of bugs it takes to taint the juice, she said she plans to continue to research the differences in the composition of wine and grape juice affected by the lady bugs.

Next Story

Recent News

Alaska Airlines Day set for Pullman campus Oct. 19

A team of executives from Alaska Airlines will be on the Pullman campus Wednesday for a series of events, including a prize-filled paper airplane toss, celebrating the airline’s partnership with WSU.

Live performance pairs music and scent

Two WSU departments are collaborating on an experience to have more sensory impact on a live audience at 7:30 p.m. on Friday, Oct. 14 in Pullman.

Find More News

Subscribe for more updates