13 replies to this topic

[pghosh]

Does anyone have experience with in-line sieves when unloading granulated sugar into silos?

 

One of our sugar suppliers do not recommend this since it could lead to foreign object contamination (from the sieve), sugar crystal degradation, increasing unloading time, etc. 

 

Wanted to know what's the general practice in this area. 

 

Thanks!

 

 

Piki

[GMO]

Thinking back, no I don't think I ever have.  But that was into the beverage industry where sieving the work in process (once made into a sugar syrup) not much later was going to be far easier.  I'd agree that any hint of moisture on that sieve and it's blocked.  Not impossible I'm sure but you'd have to keep it dry.

[TimG]

Used gravity sieves in line while bagging (sugar industry). I can't say foreign object contamination (from the sieve), sugar crystal degradation, was ever an issue. The sieves were used to catch and monitor deviations in crystal size though. I had a series of shaker sieve screens (big boys, supersack size) in decreasing order and the amounts of crystal (sugar) caught on each screen recorded (quality verification step) at intervals then bagged for rework/regrading. It was NOT used as a food safety or HACCP point..

What would be your purpose or end goal with an inline sieve? 'increasing unloading time' will absolutely be a thing...

[pghosh]

Goal is to remove foreign objects (e.g. pieces of gasket) from entering our silo. 

[jfrey123]

We sieved and sifted a fair amount of sugar in my first job at a spice plant.  One we had large shaker type and it could be painfully slow depending on the mesh size needed.  It flows quickly enough with larger sizes, but you have to ask yourself what sized FM you're trying to catch.  Pieces of gaskets would range from a finger sized half of a gasket to notoriously small fragments.  Your supplier is correct that adding a sieve introduces a slight risk from other FM but I can't imagine "crystal degradation" being a thing.

 

It's weird your supplier is concerned though.  They sold you the sugar, why do they care what you do with it?  Other than that they're concerned FM found during receiving can be pinned on them and they can't argue it came from your silo/process...

[nwilson]

Never handled sugar in silos, however have with wheat flour, and we sieved the flour at the intake and at the outtake inside the building.  As others have said I would keep the sieve dry and review the screen after loading for FM.  

 

Don't see why a sieve would degrade sugar though this comment has me stumped.  

[TimG]

I know if we didn't go from large to small with our series of shaker sieves and if they weren't cleaned/checked at the right frequency it would compact on the screen and pulverize the crystal. I guess that is technically degrading the sugar and maybe what is being referred to.

[pghosh]

finally one of our sugar suppliers recommended a filter screen (BTI's pneumatic conveying filter screen) that we will be installing.

Appreciate your feedbacks and comments in this topic. 

[GMO]

Never handled sugar in silos, however have with wheat flour, and we sieved the flour at the intake and at the outtake inside the building.  As others have said I would keep the sieve dry and review the screen after loading for FM.  

 

I was probably just thinking the intake point was not the driest but it was a beverage plant.

 

Interestingly; flour sieves.  Hilariously we were always required to sieve flour too.  But only white flour.  Wholemeal and wholegrain obviously couldn't be sieved and white flour is sieved to within an inch of its life. 

Nobody could ever tell me why I needed to sieve the white flour but not the wholemeal as a result...

[nwilson]

I was probably just thinking the intake point was not the driest but it was a beverage plant.

 

Interestingly; flour sieves.  Hilariously we were always required to sieve flour too.  But only white flour.  Wholemeal and wholegrain obviously couldn't be sieved and white flour is sieved to within an inch of its life. 

Nobody could ever tell me why I needed to sieve the white flour but not the wholemeal as a result...

 

Whole meal isn't sieved due to removing some of the nutrients through that process.  In a "white" flour the sieving was more for a quality aspect of clumping.  Flour mills and the products are an interesting process and the white (even unbleached) was more susceptible to moisture.  Also we received only unbleached enriched and unenriched into silos with bulk tanker trucks, all other flours were bagged.  

[GMO]

Whole meal isn't sieved due to removing some of the nutrients through that process.  In a "white" flour the sieving was more for a quality aspect of clumping.  Flour mills and the products are an interesting process and the white (even unbleached) was more susceptible to moisture.  Also we received only unbleached enriched and unenriched into silos with bulk tanker trucks, all other flours were bagged.  

 

I know why we can't sieve wholemeal and whole grain.  I was meaning the reasons given for sieving white were food safety, not clumping.  If you get moisture in your silo you have other issues.  Bags also have a risk of contaminating the flour in opening.

 

It was a rhetorical question.  If there is a risk with white flour there is a risk with other flours was my point.

[Tony-C]

 I'm lead to believe that mice don't like wholemeal/grain, that is why white flour is sieved:

 

 Mouse in Bread.png   995.34KB   1 downloads

 

 

 

 

[Dr Vu]

any material  moving that high a pressure can result in cavitation-erosion, either from you, the supply or even the truck bringing in the load.  having a sieve doesn't hurt

 

And in other industries, it serves two purposes: controlling the crystal sizes, as sizing affects the quality of the  final product

[GMO]

 I'm lead to believe that mice don't like wholemeal/grain, that is why white flour is sieved:

 

Mouse in Bread.png

 

 

Ah that old chestnut...

 

Very funny.

 

But I did go to a bakery once where they had "currently unused" tins being stored outside.  They were loathe to get rid of them because "ooh, well we use them sometimes...."  I showed them this picture and suggested they might consider how it could have occurred.

 

 

My point before was that genuinely, in the HACCP plan for the same site they had a CCP on sieving for the white flour (debatable anyway) but they didn't sieve the wholegrain and wholemeal which was being decanted from bags.  While the bag was unlikely to be a food safety hazard, at least not one causing significant harm, the risk of some of that bag getting into the flour was pretty high and that flour had not been sieved by the supplier to any significant degree whereas the white flour was sieved to death.

 

So my question to the HACCP team leader was "explain to me the hazard which is present in the white flour and absent in the whole meal?"