Pressure cooking and pressure canning

My friend, PIO extraordinaire and around great guy Matt Shipman asked Natalie and I about electric pressure cookers a couple of weeks ago, he was interested in answering questions that folks may have about whether they are safe to use. Here are the results of our conversation.

Electric pressure cookers, like the Instant Pot, have grown in popularity in recent years. One reason for this is that they allow people to prepare meals more quickly. But a lot of people aren’t sure why electric and stovetop pressure cookers prepare food faster than conventional stovetop cooking. And many people also wonder whether pressure cookers are actually safe.

You have questions, we have answers.

Why does food cook more quickly under high pressure? (Or, why does food cook more quickly in an Instant Pot?)

Let’s talk about heat.

Hot air rises. So, when you cook in a regular pot on your stove, a lot of the heat escapes. When moisture in the food turns into steam (which happens at 212 degrees Fahrenheit if you’re at sea level), a lot of that moisture also escapes through evaporation.

But when you’re cooking in a pressure cooker, there’s nowhere for that hot air and steam to go – it’s trapped.

“Because the hot air and steam are trapped, a pressure cooker allows you to heat the moisture – steam and water – above its normal limit of 212 degrees Fahrenheit,” says Ben Chapman, a food safety researcher at NC State University. “And the pressure cooker traps that hot air and moisture with the food, which expedites the cooking process.

“In other words, the moisture surrounding the food itself reaches higher temperatures than it would without the pressure, which speeds up the chemical processes involved in cooking. But the food doesn’t dry out like it would in an oven or on a stovetop, because the moisture has nowhere to go.”

Are pressure cookers risky to use?

No, not usually.

Air and steam expand as they heat up. So, if no hot air and steam is allowed to escape, a pressure cooker can explode.

“Most modern pressure cookers have a safety valve that is designed to release hot air and steam when the pressure inside the vessel reaches a certain point,” Chapman says. “Once the pressure has been relieved, the valve shuts again.

“Modern pressure cookers should also have a release valve that allows you to vent hot air and steam before opening the lid. That’s important, because you don’t want the lid to fly off, or to get scalded by steam when you open the lid. (Even with the release valve, it’s a good idea to open the lid away from you.) In some models, the safety and release valves are located in the same part of the cooker.”

Can I cook frozen food in a pressure cooker? 

You can cook frozen food in anything. The real question is: “Is it safe to cook frozen food in a pressure cooker?” And the answer is yes.

“The food safety concern here is that you don’t want foods – like raw meat or poultry – to be in the temperature ‘danger zone’ for a long time,” says Natalie Seymour, a food safety extension associate at NC State. “That can happen if you’re cooking frozen foods in a crockpot or a slow cooker, or even in the oven.

“The danger zone is between 41 degrees and 135 degrees Fahrenheit (5-57.2 degrees Celsius), which is the temperature range that promotes pathogen growth,” Seymour says. “It’s also the temperature range that allows pathogens to produce toxins that can persist even after the temperature gets high enough to kill the pathogens themselves. Just killing the pathogens won’t make food safe if they have already created heat-stable toxins.”

In short, you can cook frozen food safely using anything, as long as you monitor the temperature to ensure that it spends less than four hours in that temperature “danger zone.” That can be challenging if you’re using a slow cooker.

“However, because of how they work, pressure cookers do a good job of getting foods through the temperature danger zone pretty quickly,” Chapman says. “That makes it safe to cook frozen foods in a pressure cooker.”

What’s the difference between a pressure cooker and a pressure canner? Can I use them interchangeably?

Pressure cookers and pressure canners are not the same thing, and you shouldn’t think of them as being interchangeable. A good rule of thumb is that you can use a pressure canner as a pressure cooker, but you cannot use a pressure cooker as a pressure canner.

“Pressure canners have to be able to reach and maintain a consistent internal temperature of 240 degrees Fahrenheit (115.5 degrees Celsius) in order to inactivate the spores that cause botulism poisoning,” Chapman says. “But pressure cookers are variable and often don’t reach temperatures of 240 degrees. Also, electric pressure cookers – like Instant Pots – run on a cycle, in which the internal temperature rises and falls. That means they can’t be used as pressure canners.”

Note: You can find additional resources for pressure canning here.

Predicting zoonotic Salmonella from livestock

Increasingly, routine surveillance and monitoring of foodborne pathogens using whole-genome sequencing is creating opportunities to study foodborne illness epidemiology beyond routine outbreak investigations and case–control studies.

Using a global phylogeny of Salmonella entericaserotype Typhimurium, we found that major livestock sources of the pathogen in the United States can be predicted through whole-genome sequencing data. Relatively steady rates of sequence divergence in livestock lineages enabled the inference of their recent origins. Elevated accumulation of lineage-specific pseudogenes after divergence from generalist populations and possible metabolic acclimation in a representative swine isolate indicates possible emergence of host adaptation.

We developed and retrospectively applied a machine learning Random Forest classifier for genomic source prediction of Salmonella Typhimurium that correctly attributed 7 of 8 major zoonotic outbreaks in the United States during 1998–2013. We further identified 50 key genetic features that were sufficient for robust livestock source prediction.

Zoonotic source attribution of Salmonella Enterica serotype typhimurium using genomic surveillance data, United States

January 2019

Emerging Infectious Diseases vol. 25 no. 1

Shaokang Zhang, Shaoting Li, Weidong Gu, Henk den Bakker, Dave Boxrud, Angie Taylor, Chandler Roe, Elizabeth Driebe, David M. Engelthaler, Marc Allard, Eric Brown, Patrick McDermott, Shaohua Zhao, Beau B. Bruce, Eija Trees, Patricia I. Fields, and Xiangyu Deng 

https://wwwnc.cdc.gov/eid/article/25/1/18-0835_article

 

Harvard Biz: How Wegmans became a leader in improving food safety

Notes from a podcast by Ray Goldberg of the Harvard Business School drawn from his case study, Wegmans and Listeria: Developing a Proactive Food Safety System for Produce

The agribusiness program Goldberg developed in 1955 continues to bring business leaders and policy makers from around the world together each year. Throughout his tenure, Ray has written over 100 articles and 24 books on the business of agriculture, including his very latest, Food Citizenship: Food System Advocates in an Era of Distrust.

He was interviewed by podcast host, Brian Kenny: Did you coin the term agribusiness?

Ray Goldberg: I did, together with John Davis. He was the Assistant Secretary of Agriculture under Eisenhower, and he became the first head of the (HBS) Agribusiness Program.

Brian Kenny: The case cites examples of foodborne illness outbreaks in the US. We’re coming on the heels of the recent romaine lettuce issue in the US, which has now occurred, I think, twice in the last few months.

Ray Goldberg: I can describe the romaine lettuce [event], because I talked to the produce manager this morning, and he tells me the cost to the industry was $100 million dollars.

The problem is that romaine lettuce itself, when cold temperatures occur, begins to blister, which make it more susceptible to listeria. When they tried to find the location of that listeria, it came from a dairy herd about 2,000 feet away from where that lettuce was grown. We have a rule that 1,200 feet is far enough, but they actually found listeria a mile away from where that lettuce was concerned, so he feels very strongly that they have to change the rules.

(They seem to be confusing Listeria with E.coli O157 in Romaine, but that’s Haaaaaaaaarvard.)

Brian Kenny: Which gets to another issue that the case raises, which is has the industry done well enough trying to regulate itself? What are some of the things the industry has tried to do?

Ray Goldberg: Under Danny Wegman’s leadership—he was the person in charge of food safety of the Food Marketing Institute that really looked at the whole industry—he got several members of the industry to sit down and create new rules with the FDA, the EPA, the USDA, and CDC, all of them saying we have to have better rules. Produce, as you know in the case, is the most valuable part of a supermarket but also the most susceptible to problems.

Brian Kenny: This gets a little bit to the topic of your book, Food System Advocates in an Era of Distrust. [What[ are the big ideas coming out of your book?

Ray Goldberg: The big ideas are two-fold, that the kind of men and women in the industry have changed from commodity handlers and bargaining as to how cheap they can buy something, or how expensive they can make something, to finally realizing that they have to be trusted. And because they have to be trusted, they have to start working together to create that trust. In addition to that, they realize that the private, public and not-for-profit sectors really need to work together. That’s why I tried to write a book to give people an inkling of the kind of men and women in this industry who really are the change-makers, who are changing it to a consumer-oriented, health-oriented, environmentally-oriented, economic development-oriented industry.

Trade live cattle, introduce next E. coli O26 sequence type

Shiga toxin–producing Escherichia coli serogroup O26 is an important public health pathogen. Phylogenetic bacterial lineages in a country can be associated with the level and timing of international imports of live cattle, the main reservoir.

We sequenced the genomes of 152 E. coliO26 isolates from New Zealand and compared them with 252 E. coli O26 genomes from 14 other countries. Gene variation among isolates from humans, animals, and food was strongly associated with country of origin and stx toxin profile but not isolation source. Time of origin estimates indicate serogroup O26 sequence type 21 was introduced at least 3 times into New Zealand from the 1920s to the 1980s, whereas nonvirulent O26 sequence type 29 strains were introduced during the early 2000s.

New Zealand’s remarkably fewer introductions of Shiga toxin producing Escherichia coli O26 compared with other countries (such as Japan) might be related to patterns of trade in live cattle.

Use of genomics to investigate historical importation of shiga toxin-producing Escherichia coli serogroup O26 and nontoxigenic variants into New Zealand

March 2019

Emerging Infectious Diseases vol. 25 no. 3

Springer Browne1, Patrick J. Biggs, David A. Wilkinson, Adrian L. Cookson, Anne C. Midwinter, Samuel J. Bloomfield, C. Reed Hranac, Lynn E. Rogers, Jonathan C. Marshall, Jackie Benschop, Helen Withers, Steve Hathaway, Tessy George, Patricia Jaros, Hamid Irshad, Yang Fong, Muriel Dufour, Naveena Karki, Taylor Winkleman, and Nigel P. French

https://wwwnc.cdc.gov/eid/article/25/3/18-0899_article

E. coli in organic milk, kefir, sparks two separate recalls in Australia

Mungalli Creek Kefir 1 L has been recalled in Cairns and Townsville due to the possible presence of E. coli, while Organic Milk Group is recalling OMG Organic Milk 1 L in Tasmania with a best before date of February 4, 2019, also for the possible presence of E. coli.

No info on what type of E. coli was found.

Raw is risky: Pet food recalled after Minn. Health finds Salmonella in a human

State officials are notifying consumers of a recall of raw turkey pet food from Woody’s Pet Food Deli. Salmonella contamination was found after the Minnesota Department of Health identified a human case linked to the pet food

The recalled product was sold in 5-pound plastic containers labeled “Woody’s Pet Food Deli Raw Free Range Turkey” and can be identified by the white date sticker on the cover of the pet food container, the state health and agriculture departments said in a statement Monday.

The product was sold at Woody’s Pet Food Deli locations in Minneapolis, St. Paul and Woodbury. The lots recalled have these use-by dates:

– Jan. 10, 2020

– Jan. 12, 2020

– Jan. 15, 2020

No other lots of Woody’s Pet Food Deli products are affected by the recall, the agencies said.

Consumers with the recalled product at home are being told to throw it out or return it to a Woody’s Pet Food Deli for a full refund and not feed the contaminated product to pets, state officials said.

Consumers with questions can contact the Woody’s Pet Food Deli stores directly or email the company at info@woodyspetdeli.com .

Sampling began after the state health department identified a human case of salmonella linked to the pet food as part of the agency’s ongoing, multistate investigation of salmonella infections coordinated by the federal Centers for Disease Control and Prevention.

Time waits for no one: Dr. Clorox — Ralph Richardson — to retire

I can’t make this stuff up.

In 2005, I had a stalker girlfriend between wives, so me and Chapman went on a road trip starting in BC, where Chapman was convinced he would be eaten by bears at some jello-fest.

We went to Seattle and looked at Marler’s fancy offices, and then to Manhattan, Kansas, home of Kansas State University, where one of my recent PhD graduates had settled.

I’m proud that the few PhD students I’ve gotten through, and the dozens of MSc students, are innovators and create great work.

But back to the tale.

The day after we arrived, Chapman and I get invited to go speak with a Canadian studies group (paid for by Canadians that fund Americans to study Canadians) and Hubbell is there because she got some money to study Quebec.

I was tired, despondent, but Ben and another grad student were saying, look at her butt.

I was more interested in her brain.

I was an independent, she was (somewhat) married, but we worked through that.

In one week, I met a girl who I’ve been with for 13 years and moved to Kansas because the president offered me a job after having lunch.

The guy left with the mess of details was Dean of the Veterinary College at Kansas State, Ralph Richardson (the details of the job, not the new girl).

The other day, Dr. Ralph C. Richardson announced his plans to retire as Dean and CEO of Kansas State University’s Olathe campus before July 1. He has served there since August 2015.

“I certainly have mixed emotions about retiring, as I’ve never enjoyed my work more and am proud of what has been achieved at the Olathe campus in the last several years,” Dr. Richardson said.

 

“President Myers and Provost Taber are leading K-State forward in unprecedented ways. I love being part of their team and working with faculty and staff, my fellow deans and other university administrators. However, it is imperative to focus on succession planning, especially with the new budget model and strategic enrollment management initiatives coming on board. I want the new leader of the Olathe campus to be well prepared to embrace the opportunities that are coming to K-State through engagement with Greater Kansas City.”

Under Dr. Richardson’s leadership, K-State used the Olathe campus to expand its outreach and services to Greater Kansas City to elevate the university’s profile in academics, research and service in the region and generate new opportunities for students and faculty.

Dr. Richardson helped establish and oversee numerous partnerships that are being used to develop a recruitment and support infrastructure for Kansas City-based undergraduate students to attend K-State and working professionals to enroll at the university’s Olathe campus.

Before his appointment overseeing the Olathe campus, Dr. Richardson served as dean of the university’s College of Veterinary Medicine for 17 years. Under his guidance, the college experienced increased student enrollment; raised more than $72 million in private support for scholarships and seven permanently endowed professorships; introduced the Veterinary Training Program for Rural Kansas, which offers a debt repayment incentive for graduates to work in rural practices in Kansas; increased faculty and staff numbers, with many receiving national and international attention for their teaching, research and service efforts; aligned research and educational programs to meet the needs of the federal government’s National Bio and Agro-defense Facility, or NBAF, which is being built just north of the college; and much more.

Dr. Richardson joined Kansas State University in 1998, coming from Purdue University where he was a professor and head of the veterinary clinical sciences department and a 22-year faculty member of the university. At Purdue, he helped establish an ongoing comparative oncology program, utilizing naturally occurring cancer in pet animals as models for people. Before starting his academic career, Richardson served in the Army Veterinary Corps and worked as a private practice veterinarian in Miami.

Back to the story.

Ralph knew me because when he was at Purdue, he signed up to AnimalNet, one of those listserves that is now obsolete but was radical at the time.

When I met him in person, he was like an old friend, because if you get an e-mail from someone every day, they are like old friends.

After another week I went back to Canada, spoke with my four daughters, and decided, I should be in Kansas. Curt Kastner (the only uninvited dude who showed up at our city hall wedding, because we didn’t invite anyone except the witnesses, much thanks Pete and Angelique) called and said, can I arrange a conference call with Ralph?

I said, why don’t I show up in person?

Next day I was on a flight. I did a TV interview at the Toronto airport as I was departing, about a raw sprouts outbreak that had sickened at least 400 in Ontario (that’s a province in Canada), and within 24 hours, I was in Ralph’s living room, because he had broken his ankle or something while hunting, and was propped up on the couch.

I told him my vision of food safety risk analysis and research and outreach, and he told me he’d see what he could do.

I went and hung out with the girl.

In December, I decided to take the girl to Canada to see if my friends approved, because my solo judgement in such areas had proven awful.

They approved.

On my birthday, Dec. 29, 2005, me and the girl were in a grocery store in Guelph, and Ralph called. He said, we’d like to make you a job offer, how’s $100,000 U.S., plus lab start-up fees?

I was ecstatic.

Within months, me and the girl had bought our own house in Manhattan, Kansas, I was brimming with ideas, the E. coli O157:H7 outbreak in spinach started in Sept. 2006 and I was splashed all over American media as someone who may know something about this stuff. Kansas State benefited, and the president would call me weekly and say, great job.

However, back in the veterinary college, the other faculty didn’t really know what to make of me: except Dean Ralph.

I got made a full professor in 2010, but the increasing bureaucracy was not to my liking.

I loved the other aspects of my job, and I loved my wife and family.

So when Dr. Amy Hubbell, formerly of Kansas State University, was offered a faculty appointment at the University of Queensland, I wasn’t gonna be the guy who said no.

It would have been real easy to stay in Kansas, but that wasn’t our style.

So Amy and Sorenne went off to Australia, and I eventually caught up.

I worked by distance at Kansas State.

But other profs started nitpicking.

Our first guest on the first day we moved into the first place we owned rather than rented in 2012 was Dr. Clorox (that’s what they called him in Korea).

Kansas State knew we were in Brisbane, I was still an employee of K-State, but no one bothered to reach out as K-State tried to set up a partnership with the University of Queensland.

I told Ralph that evening, no hard feelings if you have to get rid of me, universities can be small sandboxes with too many and too big egos.

I had presented options for on-line course in food safety policy, a massive open on-line course (MOOC) in food safety, take a 20 per cent pay cut and was repeatedly told my performance as a faculty member was above average – but I got fired for not being there to hold my colleagues hand during tea.

The bosses at Kansas State University determined I had to be on campus, I said no, so I was dumped.

Full professors can get dumped for bad attendance.

I love my wife and family. And that’s where my allegiance lies.

It’s been harder than I thought it would be, I’ve unfortunately expressed my rage to my wife at silly times in silly ways, my brain is degenerating for a variety of reasons, but I’m optimistic, and in addition to the Kastners, Dr. Clorox has been a big fan and a good friend.

Ralph, thanks for all you’ve done for Amy and I, enjoy that retirement, and try not to drive Bev crazy hanging around the house.

The only nut butter I really like is peanut butter

Foodborne pathogens seem to like lots of nut butters. This week’s pathogen in nut butter news comes to us from Thrive Market and surprise, it’s Listeria, not Salmonella.

According to Thrive Market, all unexpired lots of their nut butters after a supplier identified some Lm in the products. I guess the expired ones are okay? Expiration dates are really for quality anyway – and we don’t really have expiration dates, but whatever.

Thrive Market, Inc, is recalling all unexpired lots of the Thrive Market-branded nut butters listed below (“Product(s)”) due to the potential for contamination with Listeria monocytogenes. On January 21, 2019, one of our suppliers notified us that it was issuing a recall of all nut butters it has manufactured since January 2018 because of a positive test for Listeria monocytogenes in recent lots. Because the safety of our members is our absolute priority, we are expanding on our supplier’s recall and are voluntarily recalling all unexpired lots of all Thrive Market-branded nut butters manufactured by this supplier.

The public health impact of the contamination isn’t really clear to me – how much Lm? Are nut butters protective in the gut to Lm like they are to Salmonella? Not sure. That’s a  question for another day.

‘Underground BBQ’ business Big Don’s Smoked Meats hit with $30,000 fines

Keeping with the Australia Day theme, David Johns of Perth Now reports that a Perth business that claims to run “clandestine and illicit” barbecues has been slapped with almost $30,000 in fines for breaching food regulations.

Big Don’s Smoked Meats was hit with the fine after the Town of Victoria Park received a smoke complaint from owner Donovan MacDonald’s St James property in August 2018.

The business was hosting one of its ‘underground barbecue’ events in the backyard of Mr MacDonald’s house.

Victoria Park chief executive Anthony Vuleta said the Town’s environmental health officers discovered Mr MacDonald was advertising cooked meats for sale and catering services — but had not registered his business properly.

The officers also discovered that those preparing the food in Mr MacDonald’s backyard did not have access to appropriate hand washing facilities.

Under the Food Act 2008 (WA), food businesses are not allowed to host events unless they are registered and have approval from the local council.

A representative of Big Don’s Smoked Meats told PerthNow via Facebook that the council’s actions were “ridiculous and very heavy handed” but declined to comment further or be interviewed on the matter.

Mr Vuleta said the Town of Victoria Park took food safety very seriously, and that “several attempts to contact Mr MacDonald before taking action were ignored”.

“He is still advertising his services while remaining unregistered,” he said

Facebook don’t know food safety: Zuckerberg once served Dorsey cold, hand-killed goat

Twitter CEO Jack Dorsey recalls as his “most memorable encounter” with Facebook boss Zuckerberg, in a new interview with Rolling Stone.

“He made goat for me for dinner. He killed the goat,” Dorsey says, before clarifying that he didn’t actually witness the slaughter. “He killed it before. I guess he kills it. He kills it with a laser gun and then the knife.”

When the interviewer rightly questions Dorsey’s use of the term “laser gun”, Dorsey says: “I don’t know. A stun gun. They stun it, and then he knifed it. Then they send it to a butcher.”

Though it was undoubtedly a smart move for Zuckerberg to send the animal to be prepared by a professional after he killed it, he might have also considered hiring a chef, with Dorsey indicating the meat wasn’t exactly cooked when it was served.

“I go, ‘We’re eating the goat you killed?’ He said, ‘Yeah.’ I said, ‘Have you eaten goat before?’ He’s like, ‘Yeah, I love it.’ I’m like, ‘What else are we having?’ ‘Salad.’ I said, ‘Where is the goat?’ ‘It’s in the oven.’

“Then we waited for about 30 minutes. He’s like, ‘I think it’s done now.’ We go in the dining room. He puts the goat down. It was cold. That was memorable. I don’t know if it went back in the oven. I just ate my salad.”

Being ruminants, goats are a significant source of Shiga-toxin producing E. Coli (STEC) with estimates of 10 per cent contaminated.

A pledge to only eat animals he personally killed was part of Zuckerberg’s yearly self-imposed challenge in 2011. Laser guns weren’t specifically mentioned in the challenge, but at this point nobody would be surprised if he used one. Apparently the goat was one of six he kept at his Palo Alto property.