We developed a new cracker and realized it has an important percentage of Checking. How can we improve them?
Thanks in advance!
As mentioned by Mr Azevedo some ingredients can hold onto water during baking increasing the moisture difference between the centre and the edge of the cracker which will inevitably lead to "Checking".
Ingredients such as modified starches are often used in cracker formulations to change the texture by causing more expansion during baking but they also may result in increased "Checking", so these ingredients need to be used with caution.
The addition of Sodium Metabisulphite or enzymes can help to reduce checking if changes to the baking profile, cooling times and docker pin design don't work
· Distribute docker pins in roll symmetrically over all biscuit surface, closest to border as possible, even in the center, if is there a logo or name of biscuit.
· Often measure moisture for border and center of biscuit, difference should be less than 0.8%. Make it a mandatory analysis for oven operators or quality assurance. Use a metal shape to cut and separate border and center, the cut area inside must correspond to 40% of total biscuit area.
· At oven, don’t use temperatures too high in first and second zones, prefer a gradual growing curve until middle of oven, then decrease it gradually for last zones. Avoid differences bigger than 40 ºC between zones (except in last zones, if necessary, for color adjustment)
· Avoid using hot water above 57 ºC in mixing or too short mixing times
· Avoid elongated shapes.
· Invert sugar, dextrose, polyols like glycerol, sorbitol (at very small concentration) and other water trapping ingredients may help.
· Give enough length in biscuit cooling belts (>1.5x oven length), biscuit temperature should be no higher than 33 ºC prior to packaging
I've found over the years of process optimization 3 main areas responsible for checking, some of which have already been addressed.
- Docker pins - if this is a new cracker shape, having these pins optimized in terms of number of pins, distribution and size all play a part in even moisture extraction through the baking process.
- Even dough piece weights/crackdown - I often get calls about checking where the customer thinks that there is an issue with their oven. Sometimes this is the case but more often the sheeting system is not optimized. By this I mean proper sheet crackdown (reduction) between all gauge rolls as well as even weights (R,C,L) across the sheet. What goes into the oven is what comes out so often times a front end issue results in a finished product issue.
- Baking - depending on the type of oven and product to be made, i may use a bell-curve temperature profile or a descending temperature profile in order to optimize the bake. Additionally, gradual exhaust is usually preferred so as to not case-harden the product which allows it to be developed more easily. This development then results in moisture being able to be extracted easier and more evenly thereby eliminating/minimizing checking.
I hope that helps,
Director, Process Technology
Reading Bakery Systems
Apart from above, please check the return band temperature. If necessary please preheat the band before wet biscuits panned on band.
Initial zones steam to be kept inside and after baking completely steam to be out to atmosphere. No convection heat to be applied. (colour and final zone by conduction and radiation only). But what ever available can rotate. If it is a forced convection oven then see the possibilities that no moisture (steam) is carried after baking,
If you are doing forced cooling then there are chances of checking in crackers. So bring the biscuit after oven out to normal room temperature by naturally. After baking biscuit reaches AC section of packing or if you arrange fan for cooling then results in checking.
Pedro the others who provided input all make great suggestions regarding evenness of weights , docker pin amount and location and oven profiling . I would add to investigate a few additional recommendations. You may need to increase bake time to improve the moisture distribution of the cracker and consider lowering your product moisture target vs what you are producing today. If you can add on and have the budget you may want to investigate adding post bake conditioning such as a dielectric drier to improve moisture distribution as well as lower and even out finished product moisture. It is also important once the cracker is baked to minimize any temperature shock the cracker may see as it is cooled . You may need to cover the conveying belts in the early sections especially in cooler areas as not expose the cracker to quickly to cooler temperatures. Another easy fix as is to build a bed of product or to shingle the product coming out of the oven onto the conveying belt so the product retains its heat longer in a larger pile or stacked configuration.