Safety information and general questions about dry curing

LowSlowJoe
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Safety information and general questions about dry curing

Post by LowSlowJoe » Fri Mar 31, 2017 15:18

So, I have yet to be able to get a good answer to one basic questions I have... but I have a lot of other questions too.

The first question is... what exactly defines a dry cure?

Background on part of why I ask. I've been making a lot of home made bacon lately, but up until yesterday, I've always cured under refrigeration and smoked at temperatures above 150F. ( 160F on average, but also up toward 175F). Recently I've been reading more and more about how wonderful you can produce bacon if it's cold smoked , and hung at cool room temperatures ( 60F, etc..) to sort of age. The basic cure formulation that I'm using is 2% salt, 1.5% sugar, 0.0156% Nitrite, and small amounts of dried spices. To this point I've made both streaky bacon and 'canadian' bacon ( cured/smoked pork loin ).

I asking initially about the definition of 'dry cure', in part because USDA regulations and/or information suggest that dry cured bacon can have a room temperature shelf life of 10 days when sliced, and 3 weeks when in slab form. Yet, injected or immersion cured bacon has no room temperature shelf life at all... so clearly there are some major differences , and presumably these differences would effect safety. I mean, if you can store sliced dry cured bacon at room temperature for 10 days... something is keeping it from resulting in really nasty stuff from developing on it.

So, what actually makes it safe to store like that? and how do I know when I've gotten to the point where it would be considered safe to store like that? In general, I don't have a need to store sliced bacon for 10 days at room temperature, but I do want to start feeling really comfortable about cold smoking and/or hanging bacon out in temperatures that are in the 'danger zone'.

Ultimately my question(s) all center around what makes 'cure' actually keep me and my family safe... Recently I've been told there are some bacteria and such , that simply are not controlled by salt or even Nitrite... One being Staphylococcus aureus, which the toxins that can be created by it, aren't even easily destroyed with high temperatures.

So what does make it safe to hang cured meat out at room temperatures ? and does the meat have to dry out first? or after? or what?
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Bob K
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Post by Bob K » Fri Mar 31, 2017 16:24

Tough questions I'll give it a shot....
LowSlowJoe wrote:The first question is... what exactly defines a dry cure?
Easier to answer is an item is cured and then dried to a safe Aw value, thus preventing further bacterial growth. Meats can be dried to be safely stored at room temp (shelf stable)

To get to that state safely is the real task. You need to control the unwanted bacterial growth until a safe Aw is achieved. We do that with temperature, salt and nitrite/nitrate.

These links will help you:
http://www.meatsandsausages.com/hams-ot ... s-sausages

By lowering water activity, food can be made safe to store. The table below shows water activity levels that can support the growth of particular groups of organisms.

Group of Micro-Organisms Minimum aw required for growth
most gram-negative bacteria 0.97
Staphylococcal toxin production (by Staphylococcus aureus) 0.93
most gram-positive bacteria 0.90
most yeasts 0.88
Staphylococcus aureus 0.86

https://www.gov.mb.ca/agriculture/food- ... lationship
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Post by LowSlowJoe » Fri Mar 31, 2017 17:34

So, then would it be fair to say that Dry Cure with regard to bacon... is not just the application of the 'cure' itself, but some level of drying of the meat , under some controlled conditions to the point where water activity had been reduced enough that it had these longer shelf life attributes.

At this point I'm still trying to wrap my head around the whole concept of Water Activity, but it seems that that is indeed one of the keys to inhibiting the growth of some of the things that salt and Nitrite don't really stop by themselves.
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Post by Bob K » Fri Mar 31, 2017 17:54

LowSlowJoe wrote:So, then would it be fair to say that Dry Cure with regard to bacon... is not just the application of the 'cure' itself, but some level of drying of the meat , under some controlled conditions to the point where water activity had been reduced enough that it had these longer shelf life attributes.
Yes it would

Aw being not directly correlated to water content is a tough concept to grasp. However those of us without Paw kits rely on shrinkage.
Butterbean was nice enough to post this chart.

http://www.wedlinydomowe.pl/en/viewtopi ... ty&start=0
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Post by Butterbean » Fri Mar 31, 2017 22:22

You are wrestling with some of the same things I wrestled with and its a very complicated subject. The butcher who took me under his wing would teach me how to do things but he never really explained WHY. I would sometimes ask him questions or pose concerns that I had gleaned from reading other's thoughts on the Net and he would just blow them off and say they were idiots so I stopped posing too many questions to him regarding stuff like this.

Problem with that is my personality and how I feel the need to understand why things are done the way they are done the way they are. In doing this research I ran across Marianski's book on fermenting sausages and this opened the doors to understanding how things work but the thing that was really allusive to me was this idea of available water. Its such a simple idea but the measurement of this is so costly but its what the USDA likes even though the Moisture Protein Ratio has been proven to be just as reliable. Though I still do not know how to accurately calculate the MPR I would love to know but I can test for water activity now that I have the equipment.

What I am about to say is not science but it is based on what I have found by my personal tests. So far, I haven't witnessed any procedure on this site which when making a dried salami or a dried whole cut of meat where it doesn't meet or exceed the aW standards when measured. In fact, I think many might be surprised at how "moist" a salami might be and still be below the aW necessary to be shelf stable.

A good example of this would be jelly. Jelly, in my mind, is wet - very wet but it has an aW of between 0.75-.80. So what I'm trying to get across here is that just because your meat may feel "damp" I can pretty well assure you - if you've followed the weight loss recommendations there is no available water to do you harm. Sure, you might get a yeast or something on it but if you've used good hygiene and used cure and the meat is of good quality and not physically damaged in some way there is little need to concern yourself with getting sick. Maybe this is what my mentor was trying to get across to me but I had to see it for myself and all this expensive equipment has only proven to me that these age old procedures were right.

In fact, I recently read a good scientific publication regarding aW where they were saying the safe zone was a tenth of a point higher than what the USDA recommends. The remark in the article was that if everything is dead at X are they twice as dead at X-0.1? I got a chuckle over that because for years I was so concerned with this. Now I am not.

I hope this helps and believe me I know where you are coming from.
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Post by DiggingDogFarm » Sat Apr 01, 2017 04:37

LowSlowJow wrote: "...what exactly defines a dry cure?"

"For country ham, dry salt cured ham, country cured shoulder ham, or dry-cured bacon, the internal salt content should be 4% when used with nitrates/nitrites or 10% without the use of nitrates/nitrites. Properly prepared dry cured hams are safe to store at room temperature (Reynolds et al.,)"

"Bacon can be manufactured without the use of nitrite, but must be labeled "Uncured Bacon, No Nitrates or Nitrites added" and bear the statement "Not Preserved, Keep Refrigerated Below 40 °F At All Times" - unless the final product has been dried according to USDA regulations, or if the product contains an amount of salt sufficient to achieve an internal brine concentration of 10% or more, the label does not have to carry the handle statement of "Not Preserved, Keep Refrigerated below ___" etc."

More precisely, 'dry-cured' has been defined as less than .92 water activity but, unfortunately, that's not a practical definition for home curers. See this post: http://wedlinydomowe.pl/en/viewtopic.ph ... ght=#31062

HTH

~Martin

Sources:
http://nchfp.uga.edu/publications/nchfp ... _pres.html
FSIS: Bacon and Food Safety Fact Sheet
Reynolds AE, Schuler GA 1982. Sausage and Smoked Meat. USDA Cooperative Extension Bulletin 865.
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Post by LowSlowJoe » Mon Apr 03, 2017 15:56

Thank you all for your input on this...

I am slowly beginning to have a better handle on all this. It is a little irritating that there aren't always really simple to understand reasons that things work, that are stated in some definitive publication. There is part of me that wants to go the way that many people seem to, and just sort of have 'faith' that stuff just works. But then another part of me wants to know as much as I can about it all.

I found this one USDA document recently , that I thought was going to shed some light on the issue of Staf Aureus... it was specifically about cold smoking fish. They did talk about the staf aureus a little, but mostly what they said was that it's never been much of a issue, even though in many places where cold smoking of fish take place, that there are conditions that might seem to be ripe for something like staf.. in the end , I was both a little relieved, but also mystified that they didn't go into any details about exactly what prevents it.. but more or less said, it isn't really a problem and therefore they weren't going to talk about it in the document.

https://www.fda.gov/downloads/Food/Food ... 545178.pdf

I'll likely continue to do more research to see if I can find more information about just what allows cured foods to hang out in environments that one might usually consider to be quite dangerous... but I am relieved to know that at some level, I'm probably overthinking some of it.

Meanwhile I think sometimes the term 'dry cure' , is kind of a misleading term... many seem to think it's just any cure without liquids , and that clearly is deceptive in the grand scheme of things.
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Post by Butterbean » Mon Apr 03, 2017 20:04

I don't think you are overthinking it just trying to understand. I'm guilty of the same and I learn more every day but am far from having a complete understanding of it. My son is a doctor and I've asked him a lot of stuff and Staph aureus is one of the things I questioned him about because it is resistant to both drying and can tolerate salt contents up to 15% so what do you do?

He told me that 1 in 3 people are infected with Staph aureus and is transmitted by mucus. This just goes to show why it is so important to use good sanitation when working with food products you will not cook and its a wonder more people don't get sick from foods on salad bars or in gas stations. The reason as I understood him is that the staph must spore to create the toxin which makes you sick so the likelihood of you making someone sick if you use good sanitation practices is extremely low. Also, think of all the people you've kissed in your life and consider that 1 in 3 had mouths full of staph yet you did not get sick. Or maybe you did but that was probably from the drinks. lol (its actually rather scary when you think of this)

However, it prefers aerobic conditions and not anaerobic and in anaerobic it cannot grow at a water level below 0.90. So it would be more possible for staph to be found on the outer skin of the product than the interior. Also, a rapid drop in pH below 5.3 slows its growth and it must grow and be happy to spore. So while possible its unlikely Staph would be a problem - if you use good sanitation.

Another thing we have going for us is the dual effects of pH and water activity. Using water activity alone in anaerobic conditions staph stops growing at 0.90. With pH alone it stops at 5.3. But together you are good when the pH is less than 5.2 and the water activity is less than 0.95 OR the ph is less than 5.3 and the water is less than 0.90. (Note, a salami with a water activity of 0.95 is a surprisingly "wet" piece of meat.

To help you out, free of charge of course, if you would like, you could take a piece of your salami and wrap it in cellophane then put in a plastic bag and mail it to me and I'll test the water activity for you so you can get an idea of what these numbers feel like in the real world. If this is something you'd like to do just pm me and I'll send you my contact info. I think you might be surprised.
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Post by LowSlowJoe » Mon Apr 03, 2017 20:35

A side note... Years ago, my wife and I both got sick, after eating some shrimp that she had prepared ( Yes, I'll blame it on her ). The shrimp was originally frozen shrimp that had been thawed and set on on the counter at a party. She re-froze the leftovers, then took it out of the freezer and cooked it in a pan, etc... Later that night, both her and I got sick, and stayed sick for 24 hours. We probably should have gone to the hospital, but did not... partly because neither one of us could stand up for more then a few minutes , or even lay down for long... no matter what we did we felt horrible. Fortunately our 1 year old daughter did not eat any of this food... The reason I mention this, is because I know believe that most likely we had eaten some of the toxin that was created by Staf Aureus... This was the only time I personally ever had what I am sure was food poisoning... and all I can say is, there was a period of time where I really had more or less wished I was dead during that ordeal... I would absolutely hate to ever make someone else anywhere near as sick as we were that day.
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Post by Butterbean » Mon Apr 03, 2017 23:42

That sounds like staph because it normally hits you within 3-4 hours of eating the infected food. 60% of all frozen shrimp has been found to contain salmonella. That is a bad bug but will last much longer - about 4-7 days of misery.

I got Staph aureus about 3 months ago after eating at McDonalds. I know it was McDonalds because that is all I ate that day and symptoms occured within 4 hours of eating a Big Mac. Toxin must have been in the lettuce is my guess.

I once contracted a severe case of amoebic dysentery and was knocking on death's door. I was dehydrated and had lost 20 lbs. I could drink a glass of water and it would leave me just as clear as it came out the tap within 5 minutes. I would have welcomed death. Ended up being cured by an old remedy which will work on any of these stomach bugs.

Recipe is easy, fill a narrow glass 3/4's full of castor oil, top this off with orange juice then add a tablespoon of baking soda and stir vigorously then hold your nose and drink the contents. Its some vile stuff and I don't think there are any organisms that can stand it so everything is flushed from your body and you are normally well within a day.
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Post by Sleebus » Tue Apr 04, 2017 01:06

BB, just curious, how much do these pawkits run?
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Post by Butterbean » Tue Apr 04, 2017 01:57

Sleebus wrote:BB, just curious, how much do these pawkits run?
I can't remember. I've intentionally forgotten what I paid for mine but they are over $1000 with many in the $4-5000 dollar range and some over $10,000.

They do give you peace of mind but once you see and feel what is "safe" you'll be surprised at how wet a sausage can be and suffice it to say things are ready before you think they are.
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Post by Sleebus » Tue Apr 04, 2017 02:41

I figured so when most places that had them wanted to give you a "quote" first! I'm a lot like you and LSJ...I'd rather see this stuff for myself, calc it out myself. That said, I love the intersection of art and science. :D
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Post by Butterbean » Tue Apr 04, 2017 05:40

Sleebus wrote:I figured so when most places that had them wanted to give you a "quote" first! I'm a lot like you and LSJ...I'd rather see this stuff for myself, calc it out myself. That said, I love the intersection of art and science. :D
I read some good research conducted by a professor in Iowa - I think - who argued against forcing this standard and his argument was the MPR was more than adequate as it hadn't been proven wrong but using aW is much simpler - if you have the equipment. It reminds me of NASA, where I'm told they spent $5 million developing a pen that would write in space. The Russians opted to use pencils. Both accomplished the same thing.
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Post by LowSlowJoe » Tue Apr 04, 2017 13:27

When I was doing my initial research into aW, I also did very brief look into meters that could measure it.. If I'm not mistaken, in addition to not really being affordable for the typical person making homemade cured meats and such... I think they also need somewhat regular calibration and such don't they?

For me personally at this point, I haven't gotten into actual sausage making, I'm trying to learn more about curing and eventually drying whole muscle meat. At this moment in time, I'm still mostly sticking with bacon , which for me includes 'Canadian' bacon. But, it's a matter of time before I want to try something like a Capocollo

Odd as it might sound... I'm actually as much interested in how to build a suitable curing chamber as I am about any particular hunk of sausage or other cured meat.

From what I'm gathering... it seems one of the keys to making good dried meat products like these, is getting the right humidity and temperature... and well back to the aW... I certainly can not afford one of those right now, especially since I've got plenty of other things to spend money on.
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