Bread Cooling2018-12-10T05:17:01+00:00
Bread Cooling

Bread cooling is an integral part of high-speed bread production.

Bread Cooling


What is Bread Cooling?

Bread cooling is an integral part of high-speed bread production. Bread has to cool before slicing and packaging. Otherwise, the crumb will be warm and gummy. Not only does this cause a problem at the slicer, gumming up the blades and creating downtime cleaning, it also leaves an undesirable moisture condensation inside the package.

Before you speed up or slow down your cooling towers, determine if you have the right conditions for cooling.

Function

During the cooling process, the baked bread loses moisture, dries out and intensifies in flavor. The starches in the loaf start retrogradating, helping setting the crumb texture. The temperature gradient between the crust and the crumb becomes zero with progressive cooling. Depending on the size and shape of the loaf, it may take up to 2 hours for the bread to completely cool. This is critical, as most bakers tend to prolong this process with excessive moisture loss. Using the conditions stated below would help prevent this.

Method

The internal temperature of the bread out of the oven is around 95º C (203º F), and the crust is somewhere around between 150º C (302º F) to 180º C (356 o F).

The internal temperature should be reduced to 35 – 40º C (95 – 104º F) at the end of the cooling cycle. This could be achieved with an external air temperature of 24º C (75º F) and a relative humidity of 85%, with an air movement to produce a 11.1º C (50º F) increase at the exhaust point.

Types/Variations

Bread is normally packaged at the legal limit of 38% moisture. A proper cooling method can avoid microbiological spoilage. These are three cooling methods:

  1. Convection: the simplest method and the most prevalent, though it does not provide accurate control of moisture loss by the cooling loaf.
  2. Conditioned air: has dry-bulb and wet-bulb temperatures control that will produce effective loaf cooling within 90 minutes.
  3. Vacuum: accelerates the vaporization of free moisture from the product and loss of the latent heat of vaporization. It’s a rapid method that is suitable for products that are unstable and prone to collapse before they cool.

6 Comments

  1. Frank February 20, 2017 at 11:54 pm - Reply

    Why do we need relative humidity of 85%? Will that benefit the cooling time or performance? How?
    Thanks

  2. Lin Carson, PhD
    Lin Carson, PhD March 10, 2017 at 6:40 pm - Reply

    Frank, the lower the humidity the better it would be. Most bakeries achieve 85% without dehumidifiers. The lower the humidity, the faster the moisture escapes and the product will cool faster. An industrial dehumidifier can help you achieve that.

  3. Steven Serafim June 26, 2017 at 12:27 pm - Reply

    If the temperature of the bakery is 84 degrees, what should the internal temp of rolls be when ready to slice?

    • Ana Rinck
      Ana Rinck August 22, 2017 at 8:51 pm - Reply

      I think you could greatly benefit from our Science of Commercial Bread Baking class. Check it out, here.

  4. Madhur September 4, 2018 at 6:34 pm - Reply

    Hello friends.
    We mass produce sliced bread at out industrial bakery. It is located countryside in India. During monsoon we are facing severe problem of molding within one or two days of packaging. The cooling time is 2.5 hrs. We are also using some preservatives giving a shelf life upto 5days. What could be the possible reasons of molding so fast? How we can over come this?

    • Ana Rinck
      Ana Rinck September 12, 2018 at 12:24 pm - Reply

      You need to make sure that you adhere to the internal temperature before packaging. Also note that both your racks and conveyor belts need to be sanitized, any mold in these will directly affect your shelf life. Check out out new Food Safety topic, Sanitation.

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