Presented as part of Technology Transfer Seminars 2023

Bakers are well aware that yeast is a crucial ingredient in baking, playing a key role in fermentation, dough rising, and flavour development. Grant Inns and Dr Hari Saripalli of Mauri presented on another aspect of yeast – the care and attention required in the handling of this important living ingredient, specifically baker’s fresh yeast, of which there are more than 1500 different strains available.

Grant and Hari explained the science behind yeast and the two critical components of yeast gassing – gas production and gas retention. An overview of commercial yeast production outlined the processes involved in getting yeast from the laboratory to the bakery, and the factors which must be controlled during production of liquid cream yeast, stabilised liquid yeast, and compressed yeast.

The emphasis of the presentation was on the handling of fresh yeast, by which they mean best practices for working with yeast, keeping yeast pure, preventing contamination, keeping yeast healthy and reducing yeast stress. As yeast works best within a specific temperature range, they highlighted temperature control as crucial when working with baker’s yeast as it can significantly impact the yeast’s activity and therefore the outcome of baked goods.

Temperature control in the bakery is allows enzymes in the yeast to work efficiently at the optimal temperature, and gas production to occur at a consistent rate.

The advantages of liquid yeast were also made clear, including minimal handling required, excellent dispersion in the dough mass in all types of mixers, good tolerance for low and high water temperatures, and consistent gassing activity. There is also the benefit of bulk storage and no packaging waste.

However proper storage of bakers’ yeast is crucial for maintaining its viability – temperature control at every stage, dark storage, a consistent environment, refrigeration, hygiene, labelling, stock rotation and monitoring for use-by dates.

Grant concluded by encouraging bakers to embrace and commit to good yeast handling and use as it plays such a vital part in creating quality products.

Presented as part of Technology Transfer Seminars 2023

Krishna Samy’s presentation on behalf of the New Zealand Flour Millers Association provided an informative summary of the lead up to and implementation of the food standard requiring flour millers in New Zealand to add folic acid to all bread making flour supplied to the baking industry.

The standard was gazetted and mandated in 2021 after many years of discussion about the safety and effectiveness of adding folic acid to flour, as well concern about the practical aspects of implementing the standard. There is now very good evidence that fortification is an effective way to reduce the rate of neural tube defects in pregnancies, and scientific evidence that adding folic acid to bread is safe.

The standard outlines that non-organic wheat flour that is sold as suitable for making bread must contain no less than 2mg/kg and no more than 3mg/kg of folic acid. The specific nature of the measurements was a particular challenge for flour millers as the amounts are so small that the folic acid has to be added to flour first to make a folic acid flour premix which is then added at 1.0 -1.2 % , approx. 250 –300 g/ 1000 kg flour.

Organic bread, bread or flour made from other grains, and wheat flour not specifically intended for bread making (such as for biscuits, cakes, pastry, and pizzas) does not need to be fortified. This provides a choice for consumers who don’t want to consume folic acid.

A two-year transition period for the implementation of the standard began in August 2021. It was a complex process for all involved.

Krishna emphasised the importance of ongoing collaboration between MPI, the flour millers and the baking industry in meeting the deadline, despite covid related shipping issues and standard equipment from Europe not meeting NZ electrical standards. It was a close call for some mills he says, but all equipment was installed and micro-dosers validated by 14 August 2023.

Meanwhile in the baking industry, bakers had to change hundreds of product labels, a process that also took place during the two-year transition period. To ensure the labels matched the content, until fortified flour became available, some bakeries had to add folic acid premix manually as fortified packaging came on line.

New Zealand Food Safety is working with flour millers to ensure they are fortifying at the right levels, and flour is surveyed periodically to check levels. Mass balancing, analytical testing, records, procedures and maintenance have all been put in place, with ongoing monitoring and testing, and Krishna says it is now business as usual for all flour mills and bakeries.

Presented as part of Technology Transfer Seminars 2023

Stan followed up his thought-provoking first presentation with a second talk about the controversial subject of energy transfer during dough mixing. The key in all cases, he said, is understanding the concept as well as the consequences of energy transfer during mixing.

90% of final bread quality is determined by what the baker chooses to do in the mixer. Dough development can’t be undone. After the dough has left the mixer, there is almost nothing the baker can do to compensate with changes in dough processing for errors in the mix, so getting it right first time is crucial.

Stan revised what goes on during mixing, starting with the dispersion and uniform blending of ingredients, and going on to cover the hydration of flour protein to form gluten, hydration of damaged starch, delivery of energy as part of dough development, incorporation of air and initiation of oxidation, creation of gas bubble structures, and the final dough temperature being higher than the sum of the ingredient temperatures, the control of which has serious implications in practical terms.

Stan shared his “house of bread quality” concept, in which the strength begins with the foundation of the development of the gluten network through the transfer of energy – work input – and the control of final dough temperature. The “walls”, he said, are the ascorbic acid-assisted oxidation of the gluten network coming from the gas that is incorporated in large quantities through mixing, and oxygen, the presence of which is an important part of the AA oxidation. The “roof” is made up of improvers that are usually expensive so there is a need to use as little as possible. Inside the “house” are the gas bubbles created during the mixing process which will grow and develop.

The whole of the baking process, Stan emphasised, is about creating a set of conditions which we don’t know quite know the outcome of until the dough goes into the oven and comes out again. He stressed the need for bakers to be consistent in the bakery too, rather than just asking flour millers to provide consistent flour.

He discussed in detail mechanical dough development, work input versus mixing time, the impact of mixing speed on crumb structure, the role of energy in dough development, the two approaches dough temperature of choosing and controlling, and then went on to elaborate on the principles and practice of controlling dough temperature. Further topics were the effect of ingredients on dough rheology, gas volume incorporated during mixing, the contribution of pressure control, cell creation and crumb structure control, and controlling oxidation and structure.

Stan’s final topic was one that could be particularly useful to bakers – how understanding mixing curves helps understand dough development and working out exactly what is happening in the mixer. He looped back to his previous presentation to emphasise that the analytical data are not wrong. The problem is that the right things are not being measured to allow prediction of baking quality.

He concluded by reiterating that it is not just about controlling energy, it is about understanding a whole series of complicated relationships occurring during the dough mixing process, all of which contribute to final bread quality.

Presented as part of Technology Transfer Seminars 2023

Following on from Sarah Robert’s presentation on reducing gluten allergenicity, Paul Johnston presented the results of research exploring another option for addressing the gluten-related disorders – developing a low allergenicity wheat.

Gluten-related disorders are a worldwide problem in the form of coeliac disease, wheat allergies and non-coeliac wheat sensitivity. As approximately 20% of worldwide calories comes from wheat and gluten is also found in a multitude of foods, the issue is significant. Solutions involve gluten avoidance (studies show that up to 30% of people actively avoid gluten), longer fermentation, gliadin extraction technologies, and wheat varieties with reduced allergenicity – the focus of this research.

Gluten epitopes are specific amino acid sequences, often high in Proline (P) and Glutamine (Q), making them resistant to intestinal degradation. An immune response to these gluten epitopes can be triggered in genetically susceptible consumers. Gluten epitopes exist within the larger gluten complex but only make up a small portion of the total gluten protein.

In breeding for a low gluten epitope, there is a need for variation in epitope concentration, which requires a wide sample of milling and feed wheats from NZ, Canada, Australia and the UK. Understanding the role of genetics versus environmental factors versus management is also essential, as is understanding the connections between epitope concentrations and other important traits such as grain protein and baking quality.

Paul emphasised baking quality and the importance of flour needing to be fit for purpose. Breeding is complex ten-year process he says, and while it is possible to shortcut the process there is never going to be one line of wheat that does everything.

Findings over the last three years in which the project has been running are that low epitope wheat won’t help those who are already suffering from coeliac disease, but there is potential way to reduce the frequency of inflammatory issues in consumers.

As results indicate that it is possible to breed for lower gluten epitope, the next steps are to identify how best to implement this knowledge into the PFR wheat breeding program and produce fit for purpose wheat cultivars with reduced gluten epitope.