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.