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Spray and save on the glazing process

06 August 2017

Food glazes are widely used in the bakery sector to improve the look and taste of baked products. Traditionally, this coating process has resulted in substantial waste. Technology advances mean that this is no longer the case. 

In bakeries the most widely applied coating medium is egg glaze, or egg wash. Increasingly, real eggs are being used, rather than egg substitutes. For continuous large-scale production processes, most coating systems are designed around traditional air-atomising nozzles or spinning disc. Their effect is to create a spray of fine droplets, enveloping the product as they pass along a conveyor. Though widely used, these systems do have limitations, which are often exposed when a company looks to increase production, diversify its product range or improve its process control.
Real-egg glaze is a costly ingredient that, traditionally has not been easy to apply on an industrial scale without waste. An independent London baker has, however, found a solution to this problem. 

Millers Bespoke Bakery, a progressive wholesale bakery since 1997, produces brioche hamburger buns at the rate of 18,000/hour from two sites in south London. Over 50% of its buns are produced at the company’s newest premises. Initially, however, there was disappointment with the glazing solution, as the performance of the triple spinning disc system originally installed to apply real-egg glaze did not meet expectations.

Marcus Miller, managing director  and founder of the bakery, working with his chief engineer Colin Mellish decided to replace the spinning disc system on all high-volume coating lines at the new plant and install advanced, fully-automated  nozzle and control system.  

They chose to use the AutoJet system, from Spraying Systems Co. Since installing the AutoJet system the company has reported a 50% reduction in the consumption of real egg glaze and clean up is much easier – while quality and consistency are accorded the same priority as sustains the bakery’s success over a wide range of more traditional products.

The system has two essential elements – the controller and PulsaJet spray nozzle – which are available in numerous configurations. The spray nozzles are electrically actuated to turn on/off repeatedly and cycling can be so fast (up to 15,000 cycles per minute) that flow may appear constant. Whereas the flow rate, spray angle and droplet size of a traditional nozzle vary with line pressure, when using PulsaJet nozzles these values remain constant.

The application rate is determined by setting the percentage of time in which the spray is on.   The system automatically monitors line speed and is able to instantly adjust nozzle flow rate as conveyor speed varies. The transfer efficiency of the egg glaze, between  nozzle and burger bun is greatly improved by spraying exactly what is required onto each product

For glazing all higher volume product Millers Bespoke Bakery is now using the new technology in place of the spinning disc methods on which it previouly relied. The technique is not confined to applying glaze or other coatings. In the production of seeded buns, for example, where the medium is water, the bakery has adopted the same method of liquid delivery for wetting  buns at pre-sprinkling stage to aid adhesion.  System components in this application are identical to those used for glazing, and have achieved comparable results.

In the wetting process, key advantages are again automatic control of liquid volume and spray characteristics, accompanied by precise targeting. Their combined effect is seen in a uniform end-product whose good looks are underpinned by good adhesion – helping the buns move smoothly through handling and transport procedures, to arrive unspoiled at the customer sales counter. 

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