Ines Hanrahan, the post-harvest physiologist at the Washington Tree Fruit Research Commission, told the Capital Press that studies currently underway should help the state apple industry get the maximum bacterial reduction.

Her comments came after the Dec. 12, and Dec. 13 recalls by the Kroger and Aldi grocery store chains of apples grown in Michigan and the Southeast over concerns about possible Listeria contamination.

Hanrahan says that’s something the Washington State apple industry wants to avoid. “We are very concerned in Washington about Listeria and have been trying to do everything possible to set up processes to avoid problems,” she said.

Every state in the United States grows apples, and 29 states raise apples commercially, but Washington State produces about 70 percent of the apples in the United States. And, the Evergreen State manufacturers about 40 percent of all U.S. apple juice products.

Hanrahan says the Washington Tree Fruit Research Commission, Washington State University, and the Center for Produce Safety at the University of California Davis are all involved in apple studies. She says these efforts will help the industry determine the best operating procedures to “get the maximum bacterial reduction.”

A Washington State apple grower, Crunch Pak, recalled sliced apples in 2013 for Listeria contamination. Then in late 2014 and early 2015, caramel apples all sourced to fresh apples from Bidart Brothers in Bakersfield, CA caused a major Listeria outbreak.

A total of 35 individuals in 12 states were sickened. All but one case required hospital care and seven people died. Bidart recalled Granny Smith and Gala apples after environmental testing found Listeria contamination in the firm’s apple-packing facility.

Hanrahan says apple growers “have no way of controlling or knowing when a potentially deadly strain enters our post-harvest environment,” but adds that they can set up extensive systems to make sure they are alerted as soon as Listeria enters storage and packing. Then she says: “we can eradicate them by thorough cleaning and sanitation programs for equipment.”

The Washington State growers are looking into various interventions–continuous flow ozone generators to controlled atmosphere storage–to bring about the highest bacteria reductions.

The apple recalls by Aldi, and Kroger so far has not been associated with any illnesses. Aldi’s removals of Fuji, Gala, Golden Delicious, and Honeycrisp apples involved sales after Dec. 13 at stores in Georgia, Indiana, Kentucky, Ohio, South Carolina, and North Carolina.

Kroger recalled Fuji and Gala apples sold between Dec. 12 and 19 at stores in Georgia, South Carolina, Alabama, Ohio, Michigan, Kentucky, Tennessee and West Virginia. It’s recall included 5-pound bags of Michigan-grown apples.

Listeria is a deadly pathogen with a fatality rate as high as 40 percent with its most significant threat to young children, the elderly, people with compromised immune systems, and pregnant women. In the caramel apple outbreak 11 of the 35 victims wher “pregnancy-related” involving either pregnant women or new-born baby, and one resulted in the loss of an unborn baby.