Sherri McGarry of the FDA said the analysis of samples taken by the federal agency at SanGar Produce & Processing Co. on Oct. 15 isn't complete. She did not know a specific day when the results would be available.
The company had hoped to receive the FDA's results as early as Friday.
"They are pending and in process right now," said McGarry, director of the agency's public health and biostatistics division in the Center for Food Safety and Applied Nutrition.
It was not clear Friday whether the FDA's sample came from the same batch taken Oct. 11 by the state and an independent lab hired by the company.
SanGar is testing to try to prove that Texas health officials wrongly traced listeria to the plant, where it cuts up and processes fruit and vegetables.
"Where's the link? Where's the evidence?" SanGar attorney Jason Galvan said of the state agency's findings. "How come they haven't produced it?"
The state health department traced six of 10 known cases of listeriosis during an eight-month period to celery processed at the SanGar plant. On Wednesday the agency shut down the plant and ordered the company to recall all the produce that has passed through the plant since January.
The agency is investigating the origins of the other four cases, which include one death.
Don Kraemer, the FDA's Office of Food Safety deputy director, has said a decision on whether to expand the recall will be made once the FDA learns more.
"This is not a hack shop," SanGar owner Kenneth Sanquist Jr. told KSAT-TV in San Antonio in a report aired Thursday night. "This is a place of the highest professional quality."
Galvan provided the AP with surveillance video of what he says is the inspection by the state health worker. He said that worker could have contaminated the samples by being dressed improperly and touching surfaces.
Texas health department spokeswoman Carrie Williams said Friday the agency also was expecting to receive a copy of a the video but that she watched it on the San Antonio station's website.
"It is disappointing that the company is using its time and energy to promote a meaningless video to the press that doesn't show anything of significance," she said. "With four deaths linked to the plant we would hope that all of their focus is on cleaning up the problems."
An independent lab that took a celery sample from the same Oct. 11 batch collected by Texas health officials tested negative for listeria, Galvan said, adding that SanGar has always conducted weekly, independent testing of its plant and has never tested positive for listeria.
The company says the state used flawed methods to collect its samples.
Williams said the agency stands by its analysis and lab results.
Health inspectors found problems with sanitation at the plant, including a condensation leak over a food production area.
The health department is trying to determine who purchased the recalled produce and whether it was used in other products. It says the produce was sold to restaurants, schools and hospitals, but that it likely wasn't sold in grocery stores. Williams said the agency has no information that the recalled produce - which also includes lettuce, pineapple and honeydew - was distributed outside of Texas.
The state health agency recommends that customers throw out or return all SanGar products.
The 10 people who contracted listeriosis lived in Bexar, Travis and Hidalgo counties, in central and southern parts of the state, and they all had serious underlying health problems, the health department said.
SanGar says some of its products are distributed, via customers, in Oklahoma.
There have been three reported cases of listeriosis in Oklahoma this year, but the state is not aware of any cases connected to the recall, Oklahoma State Department of Health spokesman Larry Weatherford said.
According to the Centers for Disease Control and Prevention, about 500 people die of listeriosis each year in the U.S., and about 2,500 people become seriously ill.
Those with weaker immune systems - including pregnant women, young children, the elderly and those battling serious illness - are most at risk of becoming seriously ill or dying because of listeriosis, the CDC says. Healthy adults and children occasionally are infected with the disease but rarely become seriously ill.
The health department prohibited SanGar from reopening the plant without agency approval.
The shutdown came about three months after the Internal Revenue Service obtained a lien against SanGar and another company, Nino's Produce. Both companies are listed as taxpayers on the lien, but Galvan said Nino's Produce is merely the landlord of the plant and not affiliated with SanGar.
In July the IRS got the lien for $137,048 in unpaid payroll taxes, according to Bexar County records. The lien shows that the firms failed to pay $77,079 for the fourth quarter of last year and $59,969 for the third quarter.