We manufacture a line of gluten free crackers. The main ingredients are pumpkin seed flour, casava flour and sunflower seed flour. We sheet the dough to around 2mm and cut to shape with rotary cutters. We don’t yet have the budget for a continuous tunnel style oven so for now we use a new Polin double rack rotating oven. We bake on perforated sheet trays at 350f for about 12 minutes. We get a pretty consistent bake with little variance to the crackers on the middle of the sheet trays and the crackers on the borders. I do think that the crunch could potentially be even sharper/harder. The most recent test on the moisture balance was 1.25% moisture content.
I would like to dial things in to get the best bake possible. I’m wondering if we should be doing a baking program with different temp phases? Also maybe less time or more time overall? Should we be using convection or steam? I’ve read a bell curve temp profile is good?
Dear Mr Mundy
It is not advisable to bake the cracker in rotary oven. I am not discouraging but that is the reality. If you bake you get uneven shape and uneven moisture only. As cracker dough even you use no gluten flour the main objective is to remove water and bake it.
I appreciate your out of box thinking of keeping the baking profile at different time interval to bake it rotary oven. In that case My Idea will be divide the total time you are going to bake into three possible phases. May be initial baking at 25% of the time and middle baking at 60% of the time and balance colouring by 15% of the time. Keep the temperature difference between 25% of time and 60% of time min.25 to35%C. when 85% of the baking done keep the temperature to get just colour. But this method you have to do trial and error and get the maximum speed and output. Oven should be capable of attaining the temperature within considerable time as you divided the entire baking time into three phases.
But I think moisture will vary from batch to batch. Pl try and see.
Hi Mundy! 1, 25% of moisture is a really good achievement.
In order to help you better, what would you like to get related to sensorial characteristics?
Hi Sonia and thanks for your reply.
I would like to get a “sharper” or “harder” crunch. Today I’m going to test a number of different crackers on the moisture balance to get a true average on moisture. Sometimes some of the crackers in the middle of the sheet tray have more of a shortbread chew with a more muted crunch and I’m imaging the moisture content in these crackers is a little higher. In an effort to get the best bake possible I’m wondering things like should we be using convection or steam and should we be using a bell curve heat profile?
The texture of Crackers can be described as light and airy and this texture is achieved by the rapid expansion of raising agents and the conversion of water into steam. To achieve this the oven needs to be hot in the first two zones with a 4 zone travelling oven baking profile for cream crackers being something like zone 1- 260 ̊ C, zone 2 - 230 ̊ C, zone 3 - 170 ̊ C, zone 4 - 100 ̊ C and a baking time of 6 minutes. As you are baking in a rack oven the baking time will be considerably longer than in a tunnel oven due to the amount of cold steel entering the baking chamber (the rack and trays) which often causes the temperature to dip so your 360 ̊ F (180 C) may not be high enough as a starting temperature and you could try 30 ̊ F or more higher to see if this helps. The danger of low baking temperatures for crackers is that the structure will set before the gasses expand,
The use of steam in the baking chamber is not desirable for baking crackers as we are trying to remove water from the product and a moist baking chamber will prevent this,
The bell shaped baking curve you mention is best suited for short dough biscuits and cookies as these products require a cooler 1st zone to allow for some product expansion (flow) with the maximum temperature being achieved at about half way through the oven then the temperature is reduced to dry the product