Pilsner Dry beer enzyme

[user 25861]

I have a brewing anomaly which has started to occur since using a pkt of Pilsner dry enzyme. My FG's are much lower than I previously achieved with the same recipe and yeast. I think this dry enzyme has contaminated one or more of my FV's.
Just racked and fined my Landlord and measured the FG. I am a little perplexed as to how the FG could have dropped to 1002. (Expected 1010). This makes approx 7.1% ABV. (Expected 5.9% ABV).
The mash efficiency was an excellent 86% but the attenuation calculates at 96%. A good & effective figure for both would be 80%. So my quandary is how can this be so? I keep my fermenting vessels clean & dry between use and use a powder Steriliser before re-use. I can only conclude that the fermenting vessel I used to make the Dry IPA using a 'dry enzyme' is contaminated with minute amounts of this dry enzyme. 2 out of the 3 beers brewed since the Dry IPA have excelled in terms of attenuation (91% & 96%). The other brew in between these two only achieved 76% attenuation so may have been brewed in a different FV not contaminated by the dry enzyme. Does this make any sense to you? Could this Pilsner Dry Enzyme survive in one of my FV's after washing, rinsing, drying and sterilisation? Do I need to heat sterilize my FV's which are plastic?
Any advice about enzyme usage would be appreciated. Thank you.

 

[Cwrw666]

I don't know anything about enzymes but I think if it were me I'd just replace my FVs.

 

[Cheshire Cat]

Are your FV plastic?

 

[user 25861]

I'm not sure if it correct to reply to my own post but I have researched and consulted with several enzyme biochemistry specialists and would like to share the information I have learned.
Conclusions: -
Rinsing, drying and metabisulphite will never remove the tiny

I don't know anything about enzymes but I think if it were me I'd just replace my FVs.

Are your FV plastic?

traces of amyloglucosidease trapped in the fermenting vessel abrasions and scratches or into the PVC surface itself. There is considerable evidence that the stability of the amyloglucosidase is enhanced by binding with the PVC.
Heat unless in excess of 100C will not denature the amyloglucosidease.
A biological detergent soaked overnight might work but would leave a scented smell and possibly a protease which would not be good for the body of the beer.
It may be possible to de-absorb the enzyme by soaking in 50g/L NaCl solution and then rinsing, sterilizing, and rinsing again. Since only minuscule amounts of enzyme are required to work this is probably impracticable.
Complete replacement of my fermenting vessels is necessary. I will keep the old ones for brewing future ‘Dry Ales’ using amyloglucosidases.

 

[YeastFace]

Perhaps a reason people might choose to add the enzyme in the mash/boil rather than fermenter?

Edit - I think I've assumed the OP used the enzyme directly in the fermenter but rereading that may not be the case.

 

[JockyBrewer]

Certainly sounds like the enzyme has carried across in the fermenter - I’d have never thought it would stay in the plastic.

Murphy’s data sheet says heating over 80C for 30 to 60 seconds will denature it.

Back some years ago people would commonly make their own boiler using a fermenting bucket and budget kettle elements, so they can take the heat if you wanted to put hot water in it, or steam it.