Air Pockets on top of basecake - rotary style cookie

One of the main factors that generate bubbles on the surface of cookies is the formation of gluten in the dough. So is important to reduce this effect. It is necessary to make adjustments of recipes and / or process, such as reducing water, adding fat, reducing kneading, lowering the temperature of the dough, lowering the gluten level of the flour, diluting the flour, etc. On the other hand, an equally important factor is cocoa powder. Cocoa contains fibers that influence the texture of the dough and consequently the absorption of water. To avoid this effect, I suggest adding cocoa over flour. This usually gives a softer dough and reduce the possibility of bubbles on the surface. 

In relation to the baking process, it is important to have the extractions closed in the 1st third of the oven, with low air circulation and the greatest heat flow from below, are some of the factors that reduce the possibility of bubbles appearing on the surface.

Hi Amaris!

We ad once the same problem on a chocolate cookie rotary moulded, and it was due to pH of the biscuit, control the pH and adjust accordingly with the addition of Sodium Bicarbonate. As you may know pH should be around 7. I think that yours should be less than that.

Hi, 

this is a known phenomenon that can appear  due to several reasons. The most Common reason is the baking of the product on a steel belt and not on a wiremesh. But there are also other factors such as the unwanted development of gluten during kneading. This is a phenomenon that occurs mainly during the hot periods of the year. In order to slow down or eliminate this phenomenon altogether, I advise you to replace the added water in the recipe with 50% sugar syrup (and of course reduce the granulated sugar in the recipe). Syrup syrup can and should be refrigerated, compared to crystal sugar for example). Other reasons can be lack of oils in the recipe. By the way, using specific types of proteases can also help. In this regard, you should contact the enzyme manufacturers. 

Best regards. 

Doron

Hi

I agree with the comment that the cause is probably gluten development.

When you mix a rotary dough the normal mixing process involves blending the fat, sugar and water together before adding the flour, As the fat is normally solid or plastic in texture during this initial mixing stage the water is dispersed in droplets in the fat/sugar mix which prevents their rapid absorption into the flour and therefore limits the formation of gluten, In warmer weather the dough fat becomes softer and can sometimes melt completely. As oil and water wont mix the the dough water will easily separate out and is available to be rapidly absorbed into the flour during the final mixing stage forming gluten.

To overcome this problem you could try replacing some of the dough water with ice flakes to help keep the fat from melting or using a lower protein flour (less gluten forming material). The addition of enzymes can also help (as mentioned previously).

Best Regards

Andrew Hughes

In the event that I am creating a gluten free cookie, what could be the drivers? This is an issue that I am seeing with both gluten continuing and gluten free formula. 

For fat, we are using a liquid fat rather than a solid fat. I have tried controlling the dough temperature with ice in the beginning stages but fear that it is affecting the dissolutions in the first mixing stage. 

When using a solid carbon steel baking band air blisters might appear because of the dough content. (Its ingredients)

If you want the best of two worlds you could replace your solid band against a perforated one. 

A perforated band holds the same baking benefits as a solid one and actually even more.

A perforated band is lighter than a solid band.

Similar cleaning as for solid bands.

A perforated band stays nice and flat because of that the holes helps getting rid of surface and internal stresses within the band material.

My suggestion is reexamine your bake time to potentially a longer residence time in the oven,  this will allow you reduce some  heat in the oven especially in the early zones as not to be too hot , this in conjunction keeping dampers closed in the early sections as not seal the outer biscuit as to allow moisture to escape more readily. 

If you require additional stack height you may require a small quantity of ammonia bicarbonate in your recipe to improve texture and consistently meet your consumer needs. . Regarding pH , I typically like to see the pH well above 7 in chocolate based products which will help deliver a better chocolate flavor delivery. 

Hello

I'd try reducing oven top temperatures at first zones, and also not directing too much % of hot air flow on top of the band. Try also closing first two zones extraction dampers. For mixing stage,  dissolve ammonium in cold water during mixing, giving enough time for it to homogenize. Reducing flour stage time and keeping dough temperature below 26°C could help.  

Make sure you are using correct flour. High W and p/l values may cause this.

If this is a rotary cutter biscuit (it is not clear, since you mention docker pins), adjusting docker pin roll pressure may help too. 

Jose