We are producing a wafer biscuit filled in layers with a flavored filling. The filling is made with fat, whey powder and maltitol.
Basically like this ones:
These retangular biscuits are covered with chocolate, but a few minutes after being covered, the biscuits open in a shape called here "crocodile mouth".
I have seen it some years ago, but I confess I don't remember well the main cause.
Please, would you have some information to help me to apply, in order to avoid this phenomenon?
‘Crocodile mouth’ is caused by the wafer taking up moisture from the filling. As the wafer expands as a result, the pressure from within it causes the chocolate shell to crack and split.
Generally the wafer/filling book is conditioned to allow any moisture from the filling to fully expand before enrobing. Depending on the scale of production this can be done online (humidity controlled tunnel) or by storing (ideally in humidity controlled conditions) for 2-3 days.
Once the wafer has fully expanded there is no longer any internal pressure to crack the chocolate coating.
Hope this helps.
In addition to what John had written, I would ask if you are using malitol as a humectant or as a sweetener. In both cases, the malitol will absorb moisture and since the wafer is of low moisture content will absorb moisture from the cream filling. This will lead to expansion of the wafer layer afterward and thus the "crocodile mouth" defect.
I hope this will be of help.
Thank you very much John! You have explained it wonderfully. I will see what would be possible to be done in order to avoid this moisture migration in the biscuits.
Yes, Mr. Hassan, you are right. The amount of Maltitol in the filling is quite big. I will try to protect it from moisture as most as we can. and one of the tests I will try, will be increasing the amount of fat in the filling, looking for water proof the constituents.
Thank you very much John and Hassan!
Good morning, Sonia,
in addition to the practical advices by John and Hassan I would like to suggest to measure and control the water activity of the wafer sheets and the filling. As long as they are identical there will be no moisure migration, hence no crocodiling. The water activity of the wafers can be adjusted by baking and conditioning, and the water activity of the filling by its recipe.
The devices for measuring the water activity have become affordable and are simple to handle.
All the best,
yes all are true.. u have to make wafer sheet conditioning for balancing ..
and also u have to choose the lowest moisture content raw material for fillings... maltitol powder, whey powder.. and also starch, milk powder etc... etc.. ..ıf u use..
I think u want to make no sugar added wafer.. so using maltitol.. sometimes we use also thermal flour for bulking agent for filling.. it is so cheaper than maltitol.. but be carefull that u have to get low mositure content thermal flour..
the raw material moisture content is so important..
The main cause for crocodiling in chocolate enrobed cream filled wafer sheet is small pin holes in the chocolate coating which allow moist air from the surrounding atmosphere to be absorbed by the low moisture wafer sheet. This localised high moisture content causes the wafer sheet to distort whilst the moisture tries to equalise throughout the sheet splitting the wafers apart.
These pin holes are formed during the enrobing process due to either air bubbles in the coating (which burst) or small fragments of the cut sheet falling off during the enrobing process. Some chocolate enrobers are equipped with two curtains and two blowing systems to try to eliminate the problem.
Conditioning on line of the sheets is a costly exercise requiring new equipment so as an alternative storage of the cut wafers in boxes may help to increase the sheet moist to a high enough level to overcome the problem.
All the best
Andrew makes a very good point on pinholing of the chocolate being a potential source of the problem. If that is the case you should be able to see the pinhole in close proximity to the crack.
Retrofitting a second curtain can be expensive and complicated too so I’d suggest a simple ‘bubble eliminator plate’ would help. A flat metal plate about 6 inches wide fitted at around a 45 degree angle below the full width of the chocolate curtain drop point will slow and then stretch the chocolate curtain and squeeze out most if not all trapped air bubbles. You may need to experiment a little with the height and angle of the plate but it generally works well in removing the bubbles.