Campden BRI: Next-generation bread quality assessment

Next-generation bread quality assessment

Assessment of quality is an essential part of the food manufacturing process. Whether part of a Quality Assurance (QA) system, where checks are made throughout the manufacturing process, or a Quality Control (QC) system system where checks are made on the finished product before it leaves the factory. The assessment of quality in regard to bread is a complex area, given the complex nature of bread!

By: Michael Adams, Product Innovation Lead, Campden BRI

+The quality of bread can be examined in a number of ways. Different bread types will have different characteristics to consider, as well as vastly different parameters within these characteristics. For example, an open structure bread, such as ciabatta, will require different quality parameters compared with a closed structure bread like a sandwich loaf.

Some parameters, such as crust appearance, aroma and flavor, are relatively easy to test using our senses. Trained staff can check these fall within expected parameters with little requirement for apparatus. Crumb color and structure, volume and texture, require either an experienced baker, or a relatively sophisticated apparatus, to identify what can be subtle differences or divergences from a specification.

Even harder to discover are intermittent quality issues, such as holes and other internal faults, that can occur within breads with no externally visible quality changes at all. The dominance of large industrial bakeries means these faults can easily transform from intermittent to common, if equipment set up or ingredient quality are not within specification. This could result in hundreds or thousands of loaves with significant defects being sent to customers.

Another aspect of quality that will be discussed in this article, is the detection of foreign objects within a loaf of bread. Foreign object complaints remain one of the largest sources of consumer dissatisfaction with food products. Metal complaints are rare, due to the widespread adoption of metal detectors within the industry, but there are a number of other sources of contamination that are non-metallic and therefore not detectable using these methods: stones, wood, plastic and glass.

This article discusses a range of methods for assessing the quality of bread focusing primarily on online methods.

Online quality detection during processing

Pre-baking

As mentioned previously, the principle of QA is to analyze the product and production unit activities to ensure that Work In Progress (WIP), or par-made products are, and remain, within specification throughout the manufacturing process. An effective QA system means that the probability of a good quality finished product emerging from the manufacturing process is high. It also means that out-ofspecification products can be identified earlier in the manufacturing process, allowing corrections to be made and waste to be reduced.

Figures 1 to 3

Within the baking process, there are a number of quality checks, such as dough consistency, dough temperature, proof height, crust color and bread core temperature.

One area in which new technologies are being applied is the quality of the dough after mixing. Bread mixing is complex and judging when bread has been mixed to the correct level requires significant experience and technical understanding. Most industrial bakeries utilize a system that mixes dough to a pre-set energy, or work input, measured in kWh. This relies on figures generated from lab-based quality checks on the flour. Work on using new sensing technologies to maximize the quality of the mixing process concentrates on two areas: + Utilizing additional data streams and artificial intelligence algorithms to modify mixing parameters + Additional sensors to analyze dough quality and ensure mixing is performed to maximum quality

Campden BRI undertook a short proof of concept project funded by Innovate UK and collaborating with RedBlack Software, to understand the potential of utilising a wide number of inputs into an algorithm. The hypothesis being that dough mixing could be altered, and dough quality improved, by understanding the optimal mixing based on multiple inputs. This trial was successful in proving that bread quality could be predicted to a reasonably accurate degree, based on observed inputs. Campden BRI are investigating the potential for a follow on project, where the system is integrated into a production scale mixer, enabling more representative factory data to be collected. This would improve the fidelity of the algorithm and generate sufficient data so that proactive improvements in mixing could be implemented in real time.

Online Infra Red (IR) and (Near Infra Red (NIR) gauges are widely used within the food industry, both on and off line. They have a number of applications and in some processes are part of feedback loops used to control processes. Work conducted at a lab and pilot scale, has shown that a portion of the NIR spectrum changes as bread dough is developed during mixing. It is hypothesised that a gauge, or sensor, could control mixing based on the changes in spectra and allow much greater control of dough quality. Again, Campden BRI is investigating the potential for research in this area and is actively looking for industrial partners.

Other areas in which new technology can help assess bread during processing include: + Proof height using lasers + Dough temperature using IR

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Post Baking

As stated earlier, assessment of quality is best performed throughout the manufacturing process, so that any problems can be rectified prior to wasting time and energy manufacturing poor quality product that will be rejected at a later stage. However, given the nature of bread, some faults do not manifest themselves until after the baking process, even if they are caused by an error much earlier in the process, or a problem with raw materials.

Given that industrial bread production uses continuous provers and ovens, bread will continue to exit the oven with potentially serious faults. Emphasis should be on speed of detection so that faults can be quickly identified and immediate corrective action taken, to minimise the amount of faulty product manufactured and in the worst scenario, dispatched to customers.

The need for speed of detection means that bakeries often rely on line-side checks, performed by trained staff. The exception to this is metal detection, which occurs either immediately prior to packaging, or soon after, depending on the packaging materials used.

Faults identified post-baking can be manifest; however, bread structure is arguably the most important characteristic to check at this stage. A number of factors, from raw material quality to almost all of the processing steps, can each have an effect on bread structure. Whilst minor deviations from specifications are unlikely to drive significant consumer dissatisfaction, more serious faults such as holes are a key complaint driver from consumers. Holes in bread can be caused by a number of factors, which are beyond the scope of this article.

Checking a small proportion of the bread made can help identify if a significant problem exists. However, if a large number of loaves are affected by holes, it is likely that these will not be detected, as holes are often an intermittent fault and unlikely to be found during routine analysis. In order to assess all loaves, a non-destructive technique is required, that is capable of scanning the internal structure of bread, at a rate conducive to being installed on a full-size industrial bakery production line.

One such system is the Biometic Mito in-line computed tomography system. This system is able to generate a full 3D reconstruction of the internal characteristics of each bread sample. Examples of 2D cross sectional CT images and corresponding photographs of cut loaves (cut after the scan) can be seen in Figures 1 to 3.

Large holes are visible (black) in the CT images. The images also reveal dense regions (bright white) where the dough was rolled after proving. A 3D generated image of each of the loaves is shown on the right of each image. These images were generated by applying averaging to the color of the CT images to eliminate minute voids and then highlighting the larger dark voids. The large voids present in each bread sample can be seen in all three of the associated images.

This system is also able to identify foreign objects, with experimental data showing its efficacy at imaging glass and bone within products, as well as denser materials such as metal.

Other online measurement technologies, such as color and temperature, are well established and widely adopted within the food and drink industry.

Final Thoughts

New technologies are emerging that will allow more data than ever to be gathered about the quality of bread throughout the manufacturing process. Adopting some of these technologies is likely to offer the significant benefit of ensuring consumers receive the highest quality product and thereby reducing dissatisfaction and complaints. +++

References

New Technologies Bulletin 55, Quality and foreign body detection using In-line X-ray CT scanning, Campden BRI, 2019

About the author

Mike Adams is the Product Innovation Lead within the Consulting Technology Group at Campden BRI and joined the organization in April 2016. He studied for a BSc (Hons) in Microbiology at the University of Manchester, graduating in 2005. Since then, Adams has worked pri© Campden BRI marily within R&D and Technical roles for multinational FMCG organizations. Most recently, he led the development of own-label products for a major high street health and wellness retailer, specializing in spotting new trends in functional foods, sports nutrition and free-from foods. His areas of interest include the linking of instrumental measurements to sensory profiling, the discovery of new functional ingredients and extending the shelf life of foods. The Product Innovation team supports a wide range of companies within the wider food and drink industry, providing innovation services, research, analysis and testing across a wide range of platforms from our state-of-the-art laboratories and pilot plant facilities.