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Vinegar vapor may help B.C. fruit growers battle post-harvest decay

B.C. fruit growers have long sought an alternative to sterilization to prevent post-harvest decay. Meanwhile the answer has waited patiently in kitchen cupboards across the country.

Simple, household vinegar may prove a valuable weapon to battle post-harvest decay, say scientists at Agriculture and Agri-Food Canada in Summerland B.C. This finding is backed by a decade of study that began when researchers discovered the decay-causing microorganisms are susceptible to acetic acid – the fundamental component of vinegar.

Studies show good potential for the commercial use of vaporized vinegar to prevent decay, says pathologist Dr. Peter Sholberg. Summerland researchers are working on application strategies to get the best results. In Canada, most producers lose about 5 percent of their crops annually to decay. Vinegar could provide producers with economic benefits and an alternative to chemicals.

“We urgently need alternatives for food sterilization,” Sholberg says. “We need to make every effort to adapt the use of vinegar vapor into our arsenal of decay prevention strategies.”

This research is part of a broad effort in science toward integrated pest management. The approach is designed to give growers more options for safe, cost-effective and sustainable pest control, says Sholberg. The vinegar progress illustrates how looking for alternative controls can sometimes turn up simple solutions. “A good pest management program benefits from truly looking at all the alternatives, and that’s what we’re doing in our battle with post-harvest decay,” he says.

In tests, stone fruit, apples and strawberries were piled into 12.7L sealed containers and fumigated with vaporized vinegar. When vaporized vinegar’s acetic acid molecules transform into gas, they easily penetrate the cracks and crevices found on fruit. Here they kill or inactivate the microorganisms working to decay fruit. Researchers tested vinegar varieties from Canada, the United States, France and Italy. These varieties included apple cider, balsamic, brown rice, malt, raspberry, red wine and white wine. They found little difference in their results. Scholberg says vinegar works well for berry crops, grapes and grain seeds. He cautions that some stone fruit and apples require careful application because they could blacken.

Initially researchers tested Glacial acetic acid which is more effective, but not as safe. Glacial acid is 14 times as strong as vinegar, making it phytotoxic when in vapor form and damaging to fruit in low concentrations. The advantages of vinegar include its antimicrobial spectrum, low phototoxicity and ability as vapor to reach parts of the fruit surface inaccessible to liquids.

Vinegar is not the perfect solution, says Sholberg, but it provides a new option. The low acetic acid content that makes vinegar safe also limits its effectiveness. Researchers list a number of steps for the efficient use of vinegar. These steps include ensuring vinegar is completely evaporated, kept at the right temperature for the necessary amount of time, as well as increasing the concentration of acetic acid. The next step in research is to improve the effectiveness of vinegar, and to continue to search for options. More work is also needed to determine the precise acetic acid concentration required in vinegar to control decay in specific kinds of fruit.

The integrated pest management program is part of Agriculture and Agri-Food Canada’s mandate to promote innovation for growth, maintain security of the food system and protect the health of the environment.

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