Coating Food Prep Surfaces With Cooking Oil May Prevent Cross-Contamination

Applying a thin layer of cook­ing oil, such as olive oil, to stain­less steel food pro­cess­ing imple­ments may deter the growth of bac­te­ria, accord­ing to new research pub­lished in the American Chemical Society’s Journal of Applied Materials and Interfaces.

The cook­ing oil does so by fill­ing in micro­scopic fis­sures and cracks on the ves­sel’s sur­face that oth­er­wise may be con­t­a­m­i­nated by bac­te­ria and left­over food residue.

“Coating a stain­less steel sur­face with an every­day cook­ing oil has proven remark­ably effec­tive in repelling bac­te­ria,” Ben Hatton, one of the paper’s authors and pro­fes­sor at the University of Toronto, said.

“The oil fills in the cracks, cre­ates a hydropho­bic layer and acts as a bar­rier to con­t­a­m­i­na­tion on the sur­face.”

Hatton told Olive Oil Times that the research began when Agri-Neo, a Canadian seed pro­duc­ing com­pany, approached him and inquired about how to pre­vent cross-con­t­a­m­i­na­tion in their seed-pro­cess­ing equip­ment.

“So they were describ­ing this prob­lem of con­t­a­m­i­na­tion. Bacteria stick­ing to the stain­less steel sur­face that was used for mix­ing,” he said. ​“They always had to clean it off and make sure there was no more bac­te­r­ial con­t­a­m­i­na­tion, so we decided to try to apply this idea from Harvard.”

Hatton had pre­vi­ously worked on how to make sur­faces slip­pery and non-adhe­sive at Harvard University by trap­ping liq­uid lubri­cant on a solid sur­face, However, he had never specif­i­cally focussed on doing this for food pro­cess­ing sur­faces.

“What we did here was focus on lubri­cant liq­uids that are food safe because you need some­thing that can mix with the food and is not going to be toxic or change the qual­i­ties in the food,” he said.

“We also needed to be super cheap because obvi­ously, it’s an indus­try that has to keep costs down, so that’s why we focussed on cook­ing oils. Because obvi­ously, it’s food safe and inex­pen­sive. And olive oil cer­tainly fits into that cat­e­gory.”

The process works by first coat­ing the sur­face with a food-safe chem­i­cal called alkyl phos­phate. When mixed with cook­ing oils, it forms an oily chain along the sur­face of the metal.

“That chem­i­cal helps to trap the oil in a really thin layer,” Hatton said. ​“If you don’t have it then the oil just kind of rolls off.”

The oily chain forms a micro­film that cov­ers the micro­scopic cracks and fis­sures in the stain­less steel, which are very dif­fi­cult to clean with­out the use of harsh and astrin­gent chem­i­cals and is often where bac­te­ria grows.

Due to how thin the layer of oil needs to be, only about a cap­ful is required, which makes the process very cost effi­cient.

“It’s not much because the amount of oil we’re talk­ing about is really thin,” Hatton said. ​“When we first put the oil on, it’s prob­a­bly in the range of about 50 microm­e­ters thick, about the same thick­ness as a piece of paper.”

A large part of the research focussed on what hap­pened to this oily chain once the stain­less steel sur­face had been cleaned. The researchers found that even though most of the oil was wiped away, some of it remained to block the scratches and fis­sures.

“Even though you wipe away most of the oil [when clean­ing the sur­face], there’s a lit­tle bit that gets stuck in those grooves and scratches,” Hatton said. ​“And that is the most impor­tant part actu­ally because that resid­ual oil blocks those sites from bac­te­ria and food get­ting in there.”

Hatton said that so far this research is only in the first stages and he hopes to part­ner with mem­bers of the cook­ing oil indus­try to both inves­ti­gate his hypoth­e­sis fur­ther as well as see whether there is any dif­fer­ence among the var­i­ous cook­ing oils.

However, he already believes that there are numer­ous appli­ca­tions for this research within the food indus­try, includ­ing the pre­ven­tion of cross-con­t­a­m­i­na­tion in large food pack­ag­ing plants and indus­trial kitchens.

“I think what’s dif­fer­ent about our work is that it is super sim­ple. We are not chang­ing the steel sur­face really, we’re adding that one mol­e­cule to the sur­face, but that’s the only change we’re mak­ing,” Hatton said. ​“I think that type of think­ing can work for other things in the food indus­try, absolutely, food pack­ag­ing.”

“Keeping bac­te­ria from stick­ing to the sur­face is really key,” he added. ​“Killing bac­te­ria is one way to do it, but if you can stop them from stick­ing that’s actu­ally just as impor­tant.”

• American Chemistry Society Journal of Applied Materials and Interfaces


• Business Standard