Problem solving – a guide

Problems that show as unexpected variations in bakery product quality do occur from time to time. Often considerable time, effort and money are required to identify the causes and solutions concerned. Unexpected quality variations are not the exclusive province of any particular size of manufacturing unit: they can occur in both large and small bakeries. Nor are they exclusive to the production bakery: even the best-controlled test bakery or laboratory can experience unexpected fluctuations in product quality.

There is no magic to problem solving. It is normally achieved through critical observation, structured thought processes and access to suitable sources of information. In this chapter we offer a guide to some of the methods that might be employed when trying to solve bakery-related problems. In doing so we must recognise that baking is a complex mixture of ingredient and process interactions so that the solutions to our problems may not always be instant in nature.

1.1 How to problem solve

Successful problem solving usually requires a methodical approach. It is perfectly possible to stumble quickly on the required solution by chance but more often than not a haphazard approach to problem solving is wasteful of time, resources and money. Not all problems are solved using exactly the same approach but the critical elements of the problem solving process are largely common.

In problem solving we normally move from the problem to the cause and finally to the corrective action. However, we must recognise that on many occasions the manifestation of a particular problem does not necessarily have a unique and identifiable cause and so there may be other intermediate steps to take into account in determining the real cause of the problem. This situation can be described schematically as follows:

→primarycause→contributingfactors→correctiveaction

Or in more simple terms as:

isseen→why→becauseof…→correctiveaction

The basic process becomes apparent if we consider two examples of problems in bread making; the first low bread volume and the second collapse of the sides of an open top pan loaf, often referred to as ‘keyholing’.

Low bread volume

Externally we observe that the bread is smaller than we expect and this may also have led to a paler crust colour because of the poorer heat transfer to the dough surface. Internally the cell structure may be more open than usual.

Since bread volume is a consequence of expansion of the dough by carbon dioxide gas from yeast fermentation and the retention of that gas within the dough matrix (Cauvain, 1998) there are two potential primary causes of this problem – lack of gas production and lack of gas retention. To separate the two we will need more observations, and an important one will be whether the rate of expansion of the dough in the prover and oven was normal or slower than usual. If the latter was the case then the primary cause of the problem is likely to be lack of gas production and potential contributing factors may include the following:

• yeast activity or level too low;

• lack of yeast substrate (food);

• dough temperature too low;

• proving temperature too low;

• proving time too short;

• salt level too high;

• proving temperature/time/yeast combination incorrect.

On the other hand if the proving had been at a normal rate and there was a lack of oven spring then this would lead us to recognise that the problem would be lack of gas retention. In this case the list of potential reasons for the problem includes:

• improver level too low;

• incorrect improver;

• combination of improver and flour too weak for process;

• enzymic activity too low;

• energy input during mixing too low;

• mixing time too short;

• dough temperature too low.

Note that the ‘dough temperature’ too low appears in both lists because of its effect on yeast activity and the effectiveness of the functional ingredients in the improver.

Keyholing

Externally we observe there is a loss of bread shape but only at the sides of the product. Internally we may see the formation of dark-coloured, dense seams, often referred to as cores. The centre crumb may be more open than we normally expect for the product concerned.

Why has this happened? Clearly we have no problems with gas production since there is no evidence for slow proving and the bread had good volume. We have clearly retained the carbon dioxide gas produced, otherwise the bread would have low volume as described above. In this case the excessive centre crumb expansion leads us to the view that in fact the gas retention is excessive.

Thus, the primary cause of the problem is excessive gas retention arising from a number of potential individual causes or combinations. The contributing factors may include:

• improver level too high;

• incorrect improver;

• combination of improver and flour too strong for process;

• enzymic activity too high;

• energy input during mixing too high;

• mixing time too long.

From the foregoing examples we can see that observation and reasoning are key elements in problem solving. The former can be readily systematised while the latter will rely heavily on the availability of suitable information to use as the basis for comparisons. The potential sources of such information are discussed below.

It is interesting to consider the process by which one might set about identifying the particular cause of a problem, such as the keyholing (excessive gas retention) of bread discussed above. The most likely mental process is one associated with probability achieved by matching the pattern of observations with ones previously experienced and remembered. When we recognise a general similarity between observation and stored image we are likely to explore in more detail the factors most likely to contribute to the pattern we observe.

One potential analogy for how we problem solve is that of a tree. The main line of observation is via the central trunk with the potential to explore branches at many points. In the case of our bread problem if we fail to identify the cause of the problem from our first consideration then we will close down that line of reasoning, go back to the main theme (the trunk) and then set off on another branch of investigation. Our route through the branches of our reasoning tree is complex and occasionally we may jump from branch to branch rather than going back to the trunk before continuing our investigation.

The length of time that we take to identify the cause and the corrective actions needed varies considerably from occasion to occasion and from individual to individual, and is more likely to be related to our accumulated knowledge and experiences rather than logical reasoning. Our abilities to recognise and match subtle patterns are probably so intuitive that we are seldom aware of them.

1.2 The record

It is common for the manufacture of bakery products to be based on some starting formulation and formal method of processing the ingredients into the finished product. This will require some form of recorded details of the ingredients to use, their quantities, equipment, process settings and timings involved. Consult any standard recipe or baking book for food preparation and you will find such details recorded for use by others. In almost all modern bakeries a formal production record will be set up for each of the product types and used by the manufacturing operatives to prepare the various items.

Invaluable in problem solving is the formal record of what was actually carried out on a particular occasion. While many operatives will keep to the prescribed formulation and processing recipe, small variations about a given value can occur and lack of information of what the actual values were for a given mix makes problem solving more difficult. It is normal for standard production specifications to allow a degree of tolerance for weights and operating conditions. For example, a temperature specification for a cake batter may be stated as 20 ± 2 °C. However, such a specification allows for replicate batters to be 18 or 22 °C and a 4 °C variation coupled with other small changes may have a larger effect of final product quality than normally considered.

A formal record of production can encompass many aspects including the following:

• Any variations in the source of the raw materials. For example, changes in flour or whole egg...