13 replies to this topic

[Ryan M.]

Hello Everyone,

 

Been a while since I've logged onto the site.  Moved across the US from California to the South (Alabama) and dealing with a frustrating boss at work has made my spare time very precious.  While I do love the South and Alabama (easy going) the weather patterns are not conducive to manufacturing consistent good quality food products.  It doesn't help that I'm basically on my own to figure out this problem and solve it.

 

At any rate...since I've been with this company, April of 2018, we have had micro issues on the liquid sugar silo / tank.  We store only liquid sucrose 65% and use about 10,000 gallons a day so we run through a good amount.  The silo capacity is 30,000 gallons.  All the incoming sugar from the tanks is clean, no APC, coliform, or yeast / mold.  Occasionally, we may get a count of 100 on APC or yeast / mold, but it is pretty rare.  The silo has positive HEPA air filtration and UV light on that air after the HEPA filter to the tank.  There is a heater on the bottom of the tank where we can heat this 

 

The issue we have is our yeast / mold counts will elevate over time and then spike up.  After we clean the silo the counts go to zero.  Sometimes we will have time to dry the silo out and sometimes we won't.  Honestly, it really hasn't made a difference as the couple times we went right back in after cleaning the silo without drying we saw the same issue to the same degree.  It appears to have worsened as the weather has become cooler here.  During the warmer months the silo would last about 8 to 12 weeks before we had to empty and clean it due to very high yeast counts.  Now, in the fall / winter months we get about 4 to 6 weeks out of the silo before we have to empty and clean it due to the very high yeast counts.

 

Sometimes there's a mold ring on the inside of the silo at the top and sometimes there is not.  I've been the one to oversee the entire emptying and cleaning process.  From a cleaning / sanitation perspective with the silo there is nothing wrong.  The interior of the silo is completely spotless after CIP.  We also know this because our micro load goes to zero after emptying and cleaning.  Additionally, I've made progress on the cleaning of the line to the silo to eliminate all dead legs (the piping is atrocious from a sanitation perspective).  However, we are challenged by a few things:

 

• HEPA / UV Light Box / System are located at the bottom of the silo (the silo is elevated with an enclosed walk in / out space for the outlet pumps, piping, and this HEPA / UV light box system.  If we have any micro load in this area I imagine it may overwhelm this system.  As such, we keep this area under the silo as clean and sanitized spotless as possible.
• The sugar receiving line is CIP'd once a week.  To be honest, this seems like overkill to me and with our atrocious piping setup we dump a lot of sugar and water underneath the silo during the process likely elevating the humidity in the area where the HEPA  / UV light box are located (pulling in that moisture to the top of the silo).
• Sugar receiving line and outlet lines have ball valves and butterfly valves (these are not CIP'able) and to really clean, have to be fully disassembled.  I swapped one of the valves out and disassembled after CIP to show we are indeed trapping sugar in the valve.

 

I know the valves need to be fixed, but am really wondering about the humidity levels and the condensation.  How can we better control this?  Especially with the temperature swings we have here.  For example today is 75oF and tomorrow will be 50oF.  Humidity levels are lower this time of year.

 

I'm also curious about the weekly CIP of the sugar receiving line.  I'm wondering if we are better off NOT washing or CIP'ing that receiving line or not as often at least.  I'll need some good info for this because it will be a tough sell with my boss.

 

Appreciate any help or insight on this.  I've been pulling my hair out over this silo / tank issue.

 

Thank you.

[Tony-C]

Hi Ryan,

 

My initial focus would be on improving the hygiene of the in/out pipework valve systems and the air filtration/UV system.

 

One big question though is have you checked the silo for cracks/pinholes? 

 

Kind regards,

 

Tony

[ntheobold84]

Hi Ryan,

 

I am assuming the liquid sugar silo is in an outside environment with no control of temperature?  This might be the reason it's causing the issue, but not confident.  At my previous employer, we had issues with high yeast and mold in our liquid sugar tank every so often, but the tank was stored in a controlled warm temperature environment.  We would do a clean of the tank and start fresh and wouldn't have an issue until so many weeks later.  We never saw a infrequent rise of yeast and mold and I assume it was because it was in a controlled temperature environment.  Not sure how to easily fix your issue.  

 

Regards,

Nicole

[lorlandini]

Ryan,

 

Is the silo insulated?    Even though i assume it does not get real cold in Alabama, insulating would keep the sucrose at a constant temperature.

 

Have you had an independent lab test the tanker truck that brings the sugar?  What about the hoses that the tanker truck uses to attach to your sucrose inlet.   Or are you using a railcar?  If using a railcar, are you using any heaters in the railcar?  If so, what type of gas are you using to prevent scorching in the rail car.  Do you check the purity of the gas?

 

I worked for a company that used sucrose in the beverage industry.  We had the same issues that you were seeing.  We did a lot of testing and inspection at our facility and at the suppliers.

 

We ended up installing a UV light system inline that the sugar passes through during the loading process and that eliminated the problem.  Unfortunately, we did not find the root cause, but the numbers told us that we did the correct thing.

 

I really think you inlet piping can be the culprit.  What type of piping?  Is it tri-clamped?  If so, when was the last gasket inspection and change?  How you test for cleanliness on the inlet piping?  Swabs (can't check all of the piping) or rinse water  will give you a better sample size).

 

Have you done any environmental testing of the area where the UV light and HEPA filter are located?  Can you take out the HEPA filter and using as aseptic a technique as possible, wash it with sterile water to a sterile container and plate the water.   This will give you an idea of the loading.  If it is very high, can you move it to the outside and protect it from the elements but giving it free flowing air instead of a hot moist dungeon?

 

Hope this helps.

Leo
 

[Ryan M.]

Hi Ryan,

 

My initial focus would be on improving the hygiene of the in/out pipework valve systems and the air filtration/UV system.

 

One big question though is have you checked the silo for cracks/pinholes? 

 

Kind regards,

 

Tony

 

 

Thanks for responding Tony.  Working on the valve improvements.  It will be slow going since there isn't an "easy low cost solution".  It will take time and capital which the company is not always quick to spend.  As far as the air filtration and UV I don't know how it can be improved.  We have the unit that was recommended for the silo from the silo manufacturer.  It has been sized appropriately for the application and pretty typical for these kinds of silos.  In my past lives with silos like these we've used the same filtration UV light setup and nary an issue with micro contamination.  Our maintenance team does a good job in PM'ing that equipment changing the pre-filters once a month and the HEPA filter and UV light annually which were recently changed about a month ago.

 

Right now I'm just toying with the idea of NOT washing / CIP'ing our sugar receiving line for a few weeks and see what that does.  If we don't wash it we don't move the ball valves so no sugar stuck in the pocket.  We'll see...

 

 

Hi Ryan,

 

I am assuming the liquid sugar silo is in an outside environment with no control of temperature?  This might be the reason it's causing the issue, but not confident.  At my previous employer, we had issues with high yeast and mold in our liquid sugar tank every so often, but the tank was stored in a controlled warm temperature environment.  We would do a clean of the tank and start fresh and wouldn't have an issue until so many weeks later.  We never saw a infrequent rise of yeast and mold and I assume it was because it was in a controlled temperature environment.  Not sure how to easily fix your issue.  

 

Regards,

Nicole

 

 

Hi Nicole.  Thanks for responding.  The silo is outside, but it does have heating about 1/3 of the way up the silo.  There is also heat tracing on the sugar receiving line.  I need to verify with maintenance these are actively working...they haven't got around to it yet.  There is a space heater underneath the silo as well and this is where the HEPA air for the headspace of the tank is drawn in.  I'm not exactly sure what temperature I should set this heater.  I've thought maybe set it to the same temperature as the sugar in the tank to prevent potential condensation, but not sure.  Did you ever find the cause of your high yeast / mold in the sugar tank?  

 

Ryan,

 

Is the silo insulated?    Even though i assume it does not get real cold in Alabama, insulating would keep the sucrose at a constant temperature.

 

Have you had an independent lab test the tanker truck that brings the sugar?  What about the hoses that the tanker truck uses to attach to your sucrose inlet.   Or are you using a railcar?  If using a railcar, are you using any heaters in the railcar?  If so, what type of gas are you using to prevent scorching in the rail car.  Do you check the purity of the gas?

 

I worked for a company that used sucrose in the beverage industry.  We had the same issues that you were seeing.  We did a lot of testing and inspection at our facility and at the suppliers.

 

We ended up installing a UV light system inline that the sugar passes through during the loading process and that eliminated the problem.  Unfortunately, we did not find the root cause, but the numbers told us that we did the correct thing.

 

I really think you inlet piping can be the culprit.  What type of piping?  Is it tri-clamped?  If so, when was the last gasket inspection and change?  How you test for cleanliness on the inlet piping?  Swabs (can't check all of the piping) or rinse water  will give you a better sample size).

 

Have you done any environmental testing of the area where the UV light and HEPA filter are located?  Can you take out the HEPA filter and using as aseptic a technique as possible, wash it with sterile water to a sterile container and plate the water.   This will give you an idea of the loading.  If it is very high, can you move it to the outside and protect it from the elements but giving it free flowing air instead of a hot moist dungeon?

 

Hope this helps.

Leo
 

 

Hi Leo, thanks for responding.  Yes, the silo is insulated and has heating panels about 1/3 the way up the silo.  I'm still waiting on maintenance to verify these are working and on.  It can get cold here, down into the teens (farenheit) below freezing, but not much colder than that.  

 

We use bulk tankers to bring in the sugar.  We do our own sampling of each tanker.  We only micro plate these in-house, but each week we take samples of our sugar from the silo to where it is injected and send to an outside lab, and plate in-house, to monitor the micro quality.  We don't have real good sample ports on our tank or the receiving line to the tank.  I've had to sanitize the line and clamps and take it apart, let is drain off a bit, and then sample to get samples from the line and the tank.  In doing this I have isolated the problem to the receiving line right at the base of the tank where the sugar goes into the tank.  In this area there is a one-way valve and a isolation ball valve.

 

As far as the inlet piping it is 3-inch stainless and there are tri-clamp fittings.  On the receiving line from the tanker to the sugar silo there is:

• In-Line perforated screen / disk.
• One way check valve (first)
• Butterfly isolation valve at receiving flow panel
• 150 feet of line to the sugar silo
• One way check valve (second)
• One way check valve (third) **This one is right below the sugar silo at the end of the receiving line
• Isolation ball valve

After we CIP'd the tank last week I pulled that isolation ball valve off and replaced with new valve.  Pulled the old valve apart and found sugar inside of it (no surprise).  We use this valve to isolate the tank from the sugar receiving line when we wash the line.  So each time there's a pocket of sugar, and the CIP solution gets right up against the valve heating it up.  So, part of me is thinking stop CIP'ing the line and see what happens...what's the worst that can happen since we only go about 6 weeks before we have to wash the silo?  The receiving line is less than a year old so all the gaskets are less than a year.  I've checked some of them and they were all in good condition.

Now...not sure if I mentioned this, but the problems started to occur when we moved the sugar receiving line.  It used to be received right next to the silo, about 15 feet of piping.  Now, it was relocated about 150 feet from the silo.  I wasn't here when it was moved so I have no idea what the old piping looked like.  I just know from my boss that all the problems started when the line was moved.  But beyond this he is about as helpful as a mound of fire ants in July.

 

We've done some environmental testing, but not a whole lot.  To be honest this was going to be my next step.  My plan is to sample the air going into the HEPA & UV, the air out from HEPA & UV, and the return air out of the silo to see what we are getting.  We did some sampling of this, but nothing real concrete or systematic.  My biggest challenge is getting my boss to sign off on any testing he doesn't see as helpful.  Some things I've done without his approval and he has slapped me on the wrist for it, even though they've been good for the facility and the process.  He is very controlling.

 

I like the inline UV light idea.  Was this something you could also CIP without disassembly?  I think this may be a good option because the valve and line fixes will surely cost us upwards of $50,000 and what happens if that doesn't fix it.

[lorlandini]

Ryan,

 

UV system can be CIP cleaned without disassembly.

 

Why are you using a ball valve for isolation.  I do not like ball valves.  I would opt for a butterfly valve.

 

 

Is all the piping new, or was some of the piping inherited from the old system?  I assume that a welder "sanitary" welded the ferrules onto the piping.  Did you check the interior surface of the welds to make sure they are 100 percent sanitary and have no fissures for sugar to hide and spoil?

 

Leo

[Ken Bookmyer]

Have you had the type of yeast identified? If it's not osmophilic I would guess it's from the CIP adding enough water for dormant spores to grow out. I recommend BCN Labs in TN for any spoilage yeast and mold issues. They solved a mold problem I was fighting and losing for a year. 

ken

[Ryan M.]

Ryan,

 

UV system can be CIP cleaned without disassembly.

 

Why are you using a ball valve for isolation.  I do not like ball valves.  I would opt for a butterfly valve.

 

 

Is all the piping new, or was some of the piping inherited from the old system?  I assume that a welder "sanitary" welded the ferrules onto the piping.  Did you check the interior surface of the welds to make sure they are 100 percent sanitary and have no fissures for sugar to hide and spoil?

 

Leo

 

Good to know about the UV system.  It won't solve our problem though since we would still have the ball valve for isolation purposes.  We really need to get that replaced as we got our micro counts back on the ball valve that was swabbed and it had quite a bit of yeast in it after CIP, over 300 CFU/mL.  They put in ball valves because they didn't understand the potential for micro issue and wanted to save money.  It is a 30,000 gallon tank so a butterfly valve wouldn't be as reliable in holding the product back.  We'll have to go with a stem and seat valve.

 

The welds on the piping are good.  I did check the ones I could inspect / see.

 

 

Have you had the type of yeast identified? If it's not osmophilic I would guess it's from the CIP adding enough water for dormant spores to grow out. I recommend BCN Labs in TN for any spoilage yeast and mold issues. They solved a mold problem I was fighting and losing for a year. 

ken

 

Thanks for the tip!  I'll see if we can do that.  My boss is very tight on the budget and he doesn't like to do any additional testing he doesn't think we'll benefit.  He didn't even want to do additional ATP swabbing after cleaning because those are a couple bucks a pop. He is an odd duck.

[Ken Bookmyer]

He's hesitant to test because he doesn't see the need. At one of the facilities I used to work at we filled a 30,000 sq ft warehouse to the ceiling with product that had mold growth because I didn't know what the problem was with a micro problem. 

If you have a process that can deal with micro after the tank he might be right it's not an issue and it won't become one, but I was doing pasteurized juice and the mold survived pasteurizing.

ken

[pHruit]

Have you had the type of yeast identified? If it's not osmophilic I would guess it's from the CIP adding enough water for dormant spores to grow out. I recommend BCN Labs in TN for any spoilage yeast and mold issues. They solved a mold problem I was fighting and losing for a year. 

ken

 

I've also seen similar occur through formation of condensation on the inside of the lid of tanks (and bulk packaging - very active yeast growth in a 24000kg flexibag is always fun...) - it can drip down into the liquid and form pools at the top that are more dilute / higher a_w, and these can become a starting point for growth.

[lorlandini]

Ryan,

 

Just use a double set of butterfly valves for isolation.  If first one fails, the second one will prevent disaster.

 

We did not discuss your actual CIP process.

 

Leo

[Ryan M.]

He's hesitant to test because he doesn't see the need. At one of the facilities I used to work at we filled a 30,000 sq ft warehouse to the ceiling with product that had mold growth because I didn't know what the problem was with a micro problem. 

If you have a process that can deal with micro after the tank he might be right it's not an issue and it won't become one, but I was doing pasteurized juice and the mold survived pasteurizing.

ken

 

Yes, we pasteurize the product after the sugar is added / injected.  However, high micro on the sugar it will impact shelf-life of our product even thought it is pasteurized.  I've seen it before in my experience at other places, and they have had that issue before here as well.  It is odd because once the growth happens and spikes everyone is asking, "What are we going to do to fix it?"  I give suggestions and paths of investigation and no one is willing to help.  I wouldn't mind if this was the only thing I was dealing with, but of course it isn't...projects on top of projects on top of SQF Maintenance with practically no help from my boss, Director of QA, and us adding over 100 associates in less than 6 months.

 

Surprisingly...we haven't had many significant issues.  Thank god our product is simple and durable; if it was milk, we'd be toast.

 

 

Ryan,

 

Just use a double set of butterfly valves for isolation.  If first one fails, the second one will prevent disaster.

 

We did not discuss your actual CIP process.

 

Leo

 

Well, we do have a one way valve right below the ball valve.  Theoretically we could use this as a backup for butterfly valve failure, but even then I'm wary.  I know...two valves as backup, but still...it is just a butterfly valve.  These are notorious for leaking by and not holding up to significant weight or pressure loads, and our valve maintenance program here is pretty sketchy.  I'm hopeful we can go the stem and seat route.

 

As far as our CIP process it is pretty typical.  The tank and the receiving line wash separately. 

• Warm pre-rinse, around 100 degree water with residual chemical from CIP recovery tank.  Enough pre-rinse to remove almost all sugar residues.
• Wash step is set to 160 degrees and uses a chlorinated caustic on the upper end of the recommended concentration from our chemical supplier (ECOLAB).  Held for 20 minutes at temperature.
• Post rinse with cool water until it meets conductivity (where all chemical is rinsed out).
• Sanitize at ambient temperature with peracetic acid, hydrogen peroxide, oxonic acid mixture.  Quite an effective sanitizer.  Concentration verified to be within range, if not we adjust and resanitize.

The tank and line flow rates are sufficient.  Line size is 3-inch so it needs minimum of 101 GPM and we're running around 120 GPM.  The tank also has a minimum pressure requirement of 10 PSI since it uses a spray dish.  I checked this and we well exceed it with 25 PSI.

 

I honestly do not see any issues with our CIP, just equipment with the valves and piping and possibly something in the environment.  Unless I am missing something else?

 

• No rinse of course after the sanitizer.

[Ken Bookmyer]

I'm inclined to think that the sanitizer is very effective but also very short-lived so after all the active ingredients have reacted with sugar you are left with some water residue and those droplets might be as you suspect the problem. 

I think you are right the best option then is to stop sanitizing so often or see if maintenance can run hot dry air in after CIP to evaporate any water residue. 

ken

[lorlandini]

Ryan,

 

CIP SOP is very robust.  I do not see any issues there.  I am leaning towards the ball valve and your piping and the possible overloaded HEPA system.

 

My previous place used an Aquafine UV light in line as per our previous discussion.  I believe they are in Valencia, California.