What should be ideal length of the cooling conveyor? We all know the traidiotnal thumb rule of 1.5 times the length of the oven but does that apply for all kind of biscuits? Factories are getting more and more compact and hence it’s difficult to fit in a complex cooling conveyor which has its own problem with regards to handling. Look forward to some practical feedback.
Yes Ritabrata , in this ergonomic production trends , some theoricals are getting unacceptable. For this topic ; factories are solving these needing in two way ;
1 . Using multilayer cooling conveyor - may be 3 or 2 layer according to factory conditions
2. Using 4-6 units of basic-simple electrical aerator - fan thorugh cooling conveyor . It makes the conveyor needing more shorter but he effectiveness of aeration should be very low for preventing quick loss of moisture and surface crackings.
it very much depends on the type of biscuit you are making. for instance with cakes it can go up to 8 times the baking length, but we see customers to have sometimes from 0,5 times the baking length to 3 times with regular biscuits.
1,5x rule is more for an estimative, usually works fine. For a deeper approach, as Jos said, it depends on the type of biscuit. If is a sandwich, basecake temperature will impact on cream filling adherence.
You must also take into account your location psychometric characteristics. For example: if you pack your biscuits above 40°C in a place where RM is high and dew point is relatively low, chances are that some moisture condensates, even inside packaging, generating organoleptic problems or even food safety issues (i.e. molds in cakes). I personally try to avoid temperatures above 30°C, in most cases.
For biscuits and cookies with dia upto around 55mm it is ok to keep 1.5times of oven length(deck system). But more than 55 to 75mm cookies you need flat cooling conveyor to avoid breakages or deck system with surface transfer instead of tumbling transfer to other deck.
In case of cake you need AC atmosphere to bring down the temperature with humidity control. Otherwise you need long cooling conveyor in case of layer cakes like that. Cakes in batch process do not have this issue.
forced cooling of biscuits will give after effect of shelf life. So cooling immediately after oven out is not recommended. You can force cool cakes and breads. For space management you can try spiral cooling system but in case of biscuit it is difficult to keep the orientation of lines in same pattern in spiral system to stack it after cooling. But this is new concept can be tried by some manufacturers.
During designing the cooling conveyor various factors to be kept in mind,
1. Biscuit weight and dimension
2. Average ambient temperature
3. Free space around cooling conveyor ( Gap from the roof, distance from wall etc.)
4. Type of final packing ( online or offline)
In multi layer cooling conveyor it is difficult to keep the lines separate which ultimately creating problem in stacker.
Any type of force cooling is not advisable for biscuit cooling mainly hard dough variety as the nonuniform cooling develops lot of strain in side the biscuit.
Good ventilation is the best solution for faster cooling.