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.

Presented as part of Technology Transfer Seminars 2023

As the third most produced cereal in the world, wheat is used in many products and vital gluten is increasingly being added to a wide range of products because of the valuable rheological properties it can add to products without adding much to cost. This has resulted in there being an increased dietary intake of total wheat gluten over the decades, often without consumers realising it.

With up to 30% of the population having the potential to develop Coeliac disease (CD), and 15-20% of people diagnosed, it potentially leaves 80% of the population exposed to risk and complications of the disease. For other consumers non-coeliac gluten sensitivity (NCGS) is an issue. Up to 15% of the population have self-reported problems with consuming gluten products, including bread. It is now also a well-known marketing strategy to target consumers looking to avoid/reduce gluten intake.

So how can we counteract the negative association of eating wheat and improve overall digestibility and comfort from eating wheat-based foods? Reducing the levels of coeliac epitopes in foods made from New Zealand wheats is one strategy being investigated by Sarah Roberts and team. They are exploring the reductions that are possible through breeding, agronomy, milling, and processing techniques prior to baking.

Plant & Food NZ “Wheats for wellness” programme is developing new cultivars and processing strategies to reduce the impact of coeliac peptides. New wheats breeds have been bred with lower levels of epitopes while maintaining wheat quality. Initial milling discoveries show that combining selected flour streams could possibly produce useable quantities of flour with epitope concentrations reduced by up to 25%. The ingestion of lower levels of gluten/epitopes may have delaying effects on susceptibility of developing CD or NCGS. Severity of the symptoms may also be reduced.

Sarah presented on a series of BIRT funded research projects looking into whether different technologies could be brought together to improve consumer tolerance (improved digestibility and comfort) to gluten found in wheat-based products. This could have profound consequences for disease incidence, pathogenesis and overall consumer health.

Results from these projects so far have shown that:

Conventional wheat breeding can be used to breed wheat cultivars with lower levels of immunogenic peptides, whilst still providing commercially feasible agronomic and baking qualities.

Milling technologies could be applied to reduced epitope levels in flours used industrially.
Sourdough starter lactobacillus strains can be isolated from sourdough starters which have the capabilities to hydrolyse gluten.

Longer fermentation times (>24 hours) are required to completely degrade gluten. A 40-60% reduction in gluten has positive effects on cytokine (inflammation) production.

Dough mixing conditions, baking temperatures and baking times have no effect on the digestibility of gluten proteins in breads although large changes in gluten aggregation and gluten macropolymer structure are seen.
The addition of yeast and increased fermentation times degrade fructan levels considerably, increasing digest comfort.

Using a combinational approach could ultimately lead to significant reductions in coeliac epitopes and FODMAPS in food products made from NZ wheats.

Presented as part of Technology Transfer Seminars 2023

Nutrients, food and health researcher Dr Andrew Reynolds is interested in what damages our health, and what costs our health system the most. Global studies show that dietary risks are the leading cause of death, due to their impact on heart disease, diabetes, and cancers. But how does this relate to what we eat in New Zealand? One area of interest is carbohydrates intakes, which make up around 47% of the energy we consume.

Both trials and cohort studies worldwide have shown that the amount of carbohydrate we consume does not matter to our health unless it is extreme – very low or high. There is far better evidence however, that it is the type of carbohydrate that is more important.

“Carbohydrates are a diverse group, ranging from simple sugars, to starch, to complex dietary fibres” Dr Reynolds said. High sugar intakes increase body weight and dental caries, dietary sources of starch appear relatively neutral to health but depend on cooking method (with deep frying and salting bad), while dietary fibre appears highly protective. High fibre intakes reduce risk of mortality, heart disease, T2 diabetes and colorectal cancer, while increasing fibre intakes improves weight, blood pressure and cholesterol.

Dietary recommendations for fibre are to have at least 25g per day, although the average intake in New Zealand hovers around 20g. One way to increase dietary fibre is to replace refined grains in the diet with whole grains. Our daily grain intake is around 238g, with only 28g or 12% being wholegrain, so there is great opportunity there to increase wholegrain intakes. But how can we change people’s preferences when the overwhelming majority of consumers want to eat refined white bread products? “People’s preferences for refined grains are not locked in for life, so this can be slowly changed overtime by always having tasty wholegrain options available, and reinforcing health messages about why they should be chosen over refined grains. In the meantime, I’m not against boosting the fibre content in refined grain products, it’s like parents trying to hide vegetables in their kid’s meals”.

Given the clear benefits with higher fibre and wholegrain intakes, Andrew was keen to find out from those present whether the flour milling and baking industries have practical and easy ways for getting more fibre and whole grains into our food supply. Digestibility, keeping qualities, the milling of whole grain to retain their benefits, crumb structure, barriers to adding fibre to bread and consumer acceptance were all up for discussion. Andrew’s health research in this area is expanding, and he aims to incorporate the practical perspectives of working with whole grain in baking and milling into his future projects.

Presented as part of Technology Transfer Seminars 2023

Stan began his working life in the laboratory of a flour mill as a quality co-ordinator. Being the one who got angry bakers on the phone telling him the flour was no good, his job was to placate them and assure them that the miller had done everything possible to ensure that the flour was within specification and the right quality. He says that in some ways flour testing has not moved on since he joined the industry. Some methods used today go back to the 1920’s, even though we make bread very differently today. He believes there is great opportunity to build on the tradition but to move forward and perhaps reduce the burden on those who work in the flour mills of the future, so they are not on the receiving end of complaints about poor quality and the underperformance of flour.

Stan suggested the key challenge starts with the question of whether flour and dough testing is predictive or indicative. He favours the latter and expressed disappointment in studies that refer to measured flour properties, correlate them with baking performance, and thereby claim a predictive testing method. What those studies fail to do, he says, is specify what the baking method is. Stan gave the example of the evaluation of flour properties and wheat varieties in the UK being based on three hours bulk fermentation for many years, a process which the UK had never used, and which the baking industry had moved way beyond.

The relevance of what is being tested and the reason behind it underpinned Stan’s challenge to bakers to view flour specifications in a new light. He appealed to millers and bakers to be collaborative, pointing out that if bakeries don’t have the right quality flour, they can’t make bread, leaving millers with no purpose either.
He stressed that flour testing and baking are complicated processes for both sides, and in those circumstances, it is necessary to start off with the most appropriate methods, rather than relying on techniques which we have used for centuries – such as stretching a piece of dough in our hands. The Egyptians did it, and we still do it he says, because we feel that we are learning something from doing that.

Stan described the typical analyses a baker is confronted with when a bread flour specification arrives in a bakery, containing terms such as moisture, protein, falling number, damages starch, water absorption, ash/colour and dough rheology. He noted how important it is to know what the standard method is being used and what the measurements actually mean to the baker.
One measurement only he says is fundamental – moisture content. But there is no standard measurement for the rest. So everything else that follows is arbitrary, enshrined in our specifications over generations, and they are not wrong but the information has to be treated differently from the way in which we would normally use numbers.

Which of those numbers tells you what the bread is going to be like? No single number tells a baker all they need to know about flour and the quality of bread it will make. Millers are producing flour for a range of uses. They don’t know what an individual bakery is going to do with it. What is right for one bakery will be no good for another. Stan suggested that bakers may not have been giving millers the right information because they don’t know what the right information is. Is there a solution to this problem?

Examining each item on the list in detail, Stan demonstrated how they are indicative, not predictive, due to the complexity of the measurements which make it difficult to use them meaningfully. The specifications also don’t consider the relation between the numbers, and no-one questions the processes used as the basis for the numbers. He went on to suggest that the real challenge is to get bakers to better understand and interpret the data they have available in the bakery and work with the flour miller to work out how to put that into a flour specification. Tell the miller what you want he urges bakers. Working together, he concludes, is better than trying to understand abstract data. We don’t need to invent new methods. We need to make better use of the information we already have and collate it in a collaborative way so we can move to a better understanding of flour specifications. But there needs to be open mindedness and a slightly different approach.

Presented as part of Technology Transfer Seminars 2023

Returned bread and single use plastic bags are two major sustainability issues facing the industrial bread sector globally. Gert-Jan Moggre presented the results of the first stage of a research project he is part of, funded by BIRT and the Bioresource Processing Alliance, aiming to address these issues in a single solution by turning bread returns into bread packaging material.

In 2022 a total of 9,605 tonnes of bread return was collected in New Zealand, 74% of which was in the North Island, and 26% in the South Island. Most of the returns were loaf (86%). The majority of this is currently going to animal feed.

A compositional analysis showed that starch made up the bulk of the composition, with a larger variation in composition for mixed dried breadcrumb than white fine breadcrumb. Protein and insoluble fibre were identified as key components to try to control as their presence will affect the final properties of any new packaging material.

The project team developed and applied a method to extract starch from mixed dried breadcrumb (MDBC) and white fine breadcrumb (WFBC) starting materials with consistent composition (starch, protein and moisture), and which demonstrated consistent mechanical properties.

Three film casting experiments were carried out to test the options for creating material for packaging, first using bread thermoplastic starch (TPS) with no plasticiser, then bread TPS with plasticiser, and finally commercial TP with plasticiser.

They found differences in mechanical properties for the WFBC and MDBC in both rheological and film forming abilities, however thin-film composites could be formed from both the MDBC and WFBC when starch extract and supernatant were combined back in.

Tensile testing established that the more plasticity in the packaging, the more biodegradable it is, so there needs to be a balance between the bags being biodegradable and able to last long enough for good use.

The next steps in the project will be to test viability in commercial application by characterising material properties of TPS as a standardised, consistent polymer product, and carrying out a technoeconomic analysis to establish capital required, operating costs of proposed processes, and other factors that may affect profitability.