The analysis

If a standard record sheet is available then the initial analysis can be as simple as considering whether the recorded data deviate from the process specification and in what direction. The effects of any changes can then be compared with existing knowledge bases (in whatever form) in order to provide the basis of a diagnosis. Sadly few bakery problems are solved with such a simplistic approach.

Almost all bakery processes include an element of elapsed time, e.g. proving, baking and lamination, which must be taken into account when analysing the causes of problems. Many larger bakery operations involve continuous production, even though they are batch fed and this adds a further complication to take into account in the analysis.

An example from our own experiences is that of a plant manufacturing baked puff pastry shells where deviations in the product dimensions were identified at the end of the baking process. In this instance the plant had to run continuously in order to be efficient and not compromise product quality (i.e. no gaps in the pastry sheet or the oven). The operation was batch fed from the mixer so that the relationship between a given mix batch and the product leaving the oven had to be established first. When this was done it then became possible to identify the contribution that any variation in the mix batch contributed to the problem.

After establishing this relationship it became clear that batch to batch variation was not the prime cause of the problem observed since simple plots of dough properties ex mixer (e.g. temperature or rheology) did not correlate with variations in product quality even when the elapsed time element had been taken into account. The solution to this particular problem lay in a plot of changes in product character with time (see Fig. 3), which upon analysis showed that the variation was more regular than first thought. At first glance it appeared to be the well-known 'shift change effect' and to some extent that was true: not, in this case, because of the operator effect but because each new shift started with a new batch of re-work to add to the virgin paste. As the re-work aged the effects on baked product character diminished. In this example a simple trend analysis provide the basis for the solution of the problem.

One analysis technique that has started to be applied to cereal science and technology is 'root cause analysis' (Stauffer, 2000). Not all bakery problems are likely to be potential subjects for this type of analysis since a key element in this technique is the brainstorming session. Brainstorming usually implies that more

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