# Safety Studies?



## Marilyn (Aug 2, 2006)

While I was cutting three good-sized pumpkins into approx 1" squares for canning, I found myself wondering how it would be possible for heat to penetrate a one-inch solid chunk of pumpkin better than it could have penetrated 1 1/2" of mushy pumpkin puree. 

The more I thought about it, the more difficult it was to imagine how on earth chunks could be safer. Are these studies available for us to read?


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## Vosey (Dec 8, 2012)

I have also wondered if studies are available somewhere. 

I suspect the safety of canning in chunks versus puree has to do with surface area. A chunk has much more surface area for contact with the heat as compared to puree when put in a jar. If the puree was smeared on a plate it would have more surface area but not packed in a jar. And the chunks are in water in the jar while the puree is being heated through the glass jar from the outside, a different transfer of heat.


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## gimpy (Sep 18, 2007)

1. It's not safer
2. It's more labor intensive
3. there's an easier way to have a better product.

Bake the pumpkin. Either whole if you don't care about the seeds or crack it open, pull out the seeds and then roast it flesh side up. Once it is soft enough to scoop put it in a stainless steel kettle and cook it down to the desired consistency, adding whatever flavors or liquids that you like (just not egg or anything that will make it gel), then ladle into jars and can


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## Marilyn (Aug 2, 2006)

*gimpy*: That's the way I did it when I first learned to can and it worked wonderfully (no one got sick either). 

*vosey*: Every time I saw the study mentioned, it was all about getting the temp in the center of the jar up to 240 degrees. I sure would like to take a look at those studies.


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## where I want to (Oct 28, 2008)

I'm having a mental debate about something similar. Whether boiling/baking a potato whole then slicing to dehydrate is just as safe as slicing a raw potato then dehydrating.
It's easier to slice a baked then refridgerated potato than try to time the boiling of slices to avoid over cooking. But then I think spreading a hot sliced potato over the drying screen would be less likely to be recontaminated than a cold potato coming into contact with hands, knives and cutting board. I know being super careful should mean it's the same but???


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## PackerBacker (Jul 17, 2013)

gimpy said:


> 1. It's not safer
> 2. It's more labor intensive
> 3. there's an easier way to have a better product.
> 
> Bake the pumpkin. Either whole if you don't care about the seeds or crack it open, pull out the seeds and then roast it flesh side up. Once it is soft enough to scoop put it in a stainless steel kettle and cook it down to the desired consistency, adding whatever flavors or liquids that you like (just not egg or anything that will make it gel), then ladle into jars and can


Chunks are safer than the process you describe.

It has to do with the water transferring the heat between the chunks.


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## arrocks (Oct 26, 2011)

There is this article about it at NCHFP http://nchfp.uga.edu/publications/uga/pumpkin_butter.html 

and the article includes links to a couple of studies that might answer your questions.
http://nchfp.uga.edu/publications/uga/pumpkin_butter.html


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## PlicketyCat (Jul 14, 2010)

where I want to said:


> I'm having a mental debate about something similar. Whether boiling/baking a potato whole then slicing to dehydrate is just as safe as slicing a raw potato then dehydrating.
> It's easier to slice a baked then refridgerated potato than try to time the boiling of slices to avoid over cooking. But then I think spreading a hot sliced potato over the drying screen would be less likely to be recontaminated than a cold potato coming into contact with hands, knives and cutting board. I know being super careful should mean it's the same but???


This has more to do with stopping enzymatic ripening and helps keep your tater slices from turning black while they're drying. But I find it's much easier to slice the raw potatoes with a mandolin and then blanch the slices before dehydrating... I use a fry basket in my kettle to give them a quick dunk and swish in salted water at a rolling boil, it doesn't take much.


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## PlicketyCat (Jul 14, 2010)

Marilyn said:


> While I was cutting three good-sized pumpkins into approx 1" squares for canning, I found myself wondering how it would be possible for heat to penetrate a one-inch solid chunk of pumpkin better than it could have penetrated 1 1/2" of mushy pumpkin puree.
> 
> The more I thought about it, the more difficult it was to imagine how on earth chunks could be safer. Are these studies available for us to read?


I think the main issue is inconsistency in the texture and amount of liquid in an individual puree. Since there is no way to standardized the density and moisture content they can't give accurate safe processing times. The Food Safety folks will always caution against a preservation method that can't be exactly replicated in everyone's kitchen every time.


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## Karen (Apr 17, 2002)

arrocks said:


> There is this article about it at NCHFP http://nchfp.uga.edu/publications/uga/pumpkin_butter.html
> 
> and the article includes links to a couple of studies that might answer your questions.


There were no studies. It's simply citations of published papers/opinions. One from 35 years ago; one other from 18 yrs ago. 

That's the real problem with home canning; thus all the controversy. No true scientific studies even exist. It's all taken from theory of scientific bacteria/spores/etc. The USDA simply draws their own conclusions based on theory and opinions. 

The USDA has us all believing if we don't do it their way, we're all going to die, or you're putting your family as high risk for death. That's simply not true. If you take into consideration all the home canners and so many different forms of canning (including thousands - if not millions, of people who _don't_ follow USDA canning procedures) here's an interesting, scientific, and accurate accounting from the CDC that I posted a couple of years ago regarding death and illness from home canned foods (food related deaths, are under law, required to be reported to the CDC by the attending physicians/hospital/medical facility):

_Only *1* person died in 8 years of reporting home canning deaths and illnesses:_

2009 - 3 illness (all were cases involving mushrooms)
2008 - 14 ilness all from the same 4 cases (family members) of home canned green bean/carrot mix - one death.
2007 - none
2006 - 2 illnesses (1 from canned mushrooms; 1 from canned meat)
2005 - none
2004 - none
2003 - none
2002 - none
2001 - none
​If you take into consideration the types of food that were the problems, it brings up the question of whether the food canned was either contaminated, or spoiled prior to canning; or (in the case of the mushrooms) poision/inedible variety of mushrooms. Also, it is also possible that improper sanitation/cleanliness could have been a factor. 

I'm not saying that we should all just have a free-for-all in how we home can our foods, but it is apparent that something isn't right in what we are told by the USDA (ie: Ball Bluebook follows only USDA guidelines as does every other published canning books due to lawsuits). But if you ever saw how they home can in other countries and survive (or how we canned in this country before pressure cookers, time tables, etc.) everyone would be dead from home canned food if we took what the USDA says as gospel.

I don't think it's any form of conspiracy or anything like that, rather that the USDA/FDA simply doesn't do _any_ studies nor do they conduct their own testing and evaluations, nor do they check to see if the opinions are based on any studies because home canning is not a priority with that Federal department. They have much more pressing issues and - mostly because funding is so limited in the area of home preserving. All the money allocated to home canning procedure mostly goes to try to keep local and state extension services afloat. It's just easier and sounds best to follow strict un-verified requirements of theory. 

So my personal thoughts are, each to his own. No one intentionally sets out to put their family in danger. Each of us has to determine what does or does not put them in danger. We're each going to draw the line at different places. Just as a Germaphobic would draw a different line than the rest of us might; or another might let their kids run barefoot in the chicken coop. Just different ends of the same spectrum; but both just as concerned for their family. 

If it makes someone feel better and safer to follow the guidelines to the measure, then I can totally understand and respect that. On the other hand, if another wishes to do it totally differently and not follow all the guidelines, I also think we need to respect that choice, after all, it is their freedom to do so. Plus there is no proof to the contrary anyway; only opinion.


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## gimpy (Sep 18, 2007)

PackerBacker said:


> Chunks are safer than the process you describe.
> 
> It has to do with the water transferring the heat between the chunks.


No. Heat transference is dependent upon the size of the pieces. Thinks heat and cool acoording to their thinnest dimension assuming a regular shape. Particles heat faster than chunks.


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## PackerBacker (Jul 17, 2013)

gimpy said:


> No. Heat transference is dependent upon the size of the pieces. Thinks heat and cool acoording to their thinnest dimension assuming a regular shape. Particles heat faster than chunks.


And your puree is ONE SOLD CHUNK.

The heat transfer is dependent on the water in the jar between the chunks.

If the puree is to thick the heat CAN'T transfer to the middle of the jar.

Pretty basic physics here.


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## gimpy (Sep 18, 2007)

PackerBacker said:


> And your puree is ONE SOLD CHUNK.
> 
> The heat transfer is dependent on the water in the jar between the chunks.
> 
> ...


No, a slurry is in no way imaginable a chunk, unless for some reason you are talking about a frozen block but it would be very strange for someone to freeze a slurry into a jar and then immediately put it into a canner. If they did the jars would explode. 

Heat transference is not between chunks. It is between water and the items being canned. In a slurry there is water between the cells. Water to water heat transfer is easy and there is little distance to travel to get into the particles. When you use chunks, you have the tissue anatomy to deal with. The water needs to transfer heat to the outer layers of cells which then have to transfer heat to the next layer etc, all the time dealing with cell walls. It is rather basic food science.

If you want to can vegetables as chunks because you want to preserve some of the texture, that's fine and sometimes preferable for culinary reasons but it is not safer. The safest is to cook things down to paste and char them to bricks. Obviously that's not what most people want to eat and so we adjust what we do accordingly. However the discussion was about pumpkin specifically and most people end up using it as a slurry in pies or baked goods and from a safety standpoint that is safer. If you plan to make pumpkin soup where some chunks would be nice that's a different issue. That's not a safety issue. That's a gustatory issue.


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## PackerBacker (Jul 17, 2013)

gimpy said:


> No, a slurry is in no way imaginable a chunk, unless for some reason you are talking about a frozen block but it would be very strange for someone to freeze a slurry into a jar and then immediately put it into a canner. If they did the jars would explode.
> 
> Heat transference is not between chunks. It is between water and the items being canned. In a slurry there is water between the cells. Water to water heat transfer is easy and there is little distance to travel to get into the particles. When you use chunks, you have the tissue anatomy to deal with. The water needs to transfer heat to the outer layers of cells which then have to transfer heat to the next layer etc, all the time dealing with cell walls. It is rather basic food science.
> 
> If you want to can vegetables as chunks because you want to preserve some of the texture, that's fine and sometimes preferable for culinary reasons but it is not safer. The safest is to cook things down to paste and char them to bricks. Obviously that's not what most people want to eat and so we adjust what we do accordingly. However the discussion was about pumpkin specifically and most people end up using it as a slurry in pies or baked goods and from a safety standpoint that is safer. If you plan to make pumpkin soup where some chunks would be nice that's a different issue. That's not a safety issue. That's a gustatory issue.


If you made a slurry it'd be fine but you're not. You then exacerbate the problem by roasting it in the oven first and removing some water. What you are making is to thick to be deemed a slurry.

But suit yourself. Lets just not pretend it's safer than chunks.



> Caution: Do not mash or puree.
> 
> For why we say not to mash or puree the squash, read


http://nchfp.uga.edu/publications/uga/pumpkin_butter.html


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## Marilyn (Aug 2, 2006)

Thank you Karen, that's exactly what I was looking for. It would be helpful if illness/death reporting practices included some investigation into food safety (mushrooms) and cleanliness issues.


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## PlicketyCat (Jul 14, 2010)

If your squash puree were very loose and wet, just shy of being soup, then it would transfer heat very well. However, if your puree was thicker and less moist, closer to a paste, then it wouldn't transfer nearly as well and could (possibly) allow critters to survive in the inside. 

Since there is no way to guarantee that everyone's puree has the same consistency and moisture content, the official SOP is not to can it at home because they have no guidelines that can guarantee it is safe.

Remember - not being able to guarantee safety DOES NOT mean that it's guaranteed to be unsafe.


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## gimpy (Sep 18, 2007)

PackerBacker said:


> If you made a slurry it'd be fine but you're not. You then exacerbate the problem by roasting it in the oven first and removing some water. What you are making is to thick to be deemed a slurry.
> 
> But suit yourself. Lets just not pretend it's safer than chunks.
> 
> ...


You seem to like pretending. I advocate baking it whole and since you keep using strawman arguments, ad hominem and moving the goal posts I'm adding you to my ignore list. I also never said that you couldn't add water in the process. Canning, Baking, Butchering, Cooking are all a lot of art as well as science. I was talking specifically about the science and on that you are wrong.


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