NZ Milk Nutrition Study

A recently completed five-year research initiative providing the New Zealand milk industry the scientific facts they need to successfully develop new high-value foods – and accurately position these foods both here in New Zealand and in the global marketplace. 

For most of us milk is just milk – either to drink a glass of it, good calcium for the bones; to add it to the likes of tea or coffee, or baked goods, or to make something out of it, such as a warming custard to pour over a favourite winter pudding, or cheese or yoghurt.  

The $13 million research project begs to differ, having established that the various milks produced in New Zealand (cow, goat, sheep and deer) are all quite different, in that each milk acts differently in the human gut – with different digestive and nutritional outcomes. What’s more, the way each milk is processed (e.g. whether UHT, powdered, homogenised, pasteurised or not – i.e. raw) also impacts digestion and nutrition. 

The 16 industry collaborators included Fonterra, Synlait, Miraka, Waiū Dairy, Tatua, the a2 Milk Company, Mataura Valley Milk, the Dairy Goat Cooperative, Maui Sheep Milk, Spring Sheep Co., Blue River Dairy, Kingsmeade Artisan Cheese, Cilantro Cheese, Landcorp/Pāmu, NIG Nutritionals and Goodman Fielder.    

The study is entitled New Zealand Milks Mean More, and referred to as NZ3M, with Riddet Institute’s Professor Warren McNabb leading the project’s team of scientists. 

As a result of NZ3M’s three research arms (milk structure and digestion, better nutrition, and new foods and consumer science) the New Zealand milk industry is now equipped to design new tailor-made high-value foods to meet the diverse and ever-changing needs of consumers here at home and around the world, says Professor McNabb.  

“Equally importantly, the NZ3M study opens up the way for science-based wellbeing messages to be developed giving consumers the confidence that what is being claimed on the likes of packaging and in advertising is scientifically proven.”  

Accordingly, New Zealand’s already internationally acclaimed portfolio of dairy products will be even more diversified in the future. 

Central to understanding how the different milks – and the way they are processed – work in the human digestive tract is a human gastric simulator (HGS) that is housed in the Riddet Institute’s laboratories on Massey University’s campus.  

This HGS ‘stomach’ takes the customary method for studying food digestion in a laboratory setting to a new level by not only incorporating the usual digestive fluids and enzymes, which are shaken and stirred, but also simulating the peristaltic movement of the human stomach making it closer to a real-life gastric system.  

It is also mimics other human stomach processes including the continuous secretion of gastric juice and the emptying of digested food, along with maintaining the usual 37˚ C temperature of human digestion.  

The research has established that each of the different milks first coagulates in the stomach into structures like ‘cheese curds’ with the consistency of the ‘curds’ varying from that akin to a firm mozzarella cheese ball, to loose, wet cottage cheese-like structures across the different milks and different processing methods. 

Goat milk formed the softest curds among the three species. Following homogenisation and heat treatments, milk from all the species formed looser curd structures. Differences were also found in the breakdown rate of the curds during digestion and the emptying of different milk components into the small intestine for further digestion and absorption. Milks that formed loose and soft curds were emptied from the HGS faster and had higher digestion rates than those that formed firm and intact curds. 

Findings from this study will inform the design and development of milk products from different ruminant species via different processing treatments to achieve different digestive outcomes. For instance, rapid delivery of proteins and amino acids may be desired for products promoting muscle growth whereas a slowly digested milk may prolong satiety and assist in weight management.  

Part of the research included a human clinical study overseen by Professor Nicole Roy, who is head of the Department of Human Nutrition at the University of Otago and delivered by NZ3M scientists at the Liggins Institute at the University of Auckland.  

Entitled TuMMI, the study used MRI (magnetic resonance imaging) to find that different treatments of milk (UHT versus pasteurised) affected the rate at which these milks emptied from the stomach, with pasteurised milk leaving the stomach earlier than UHT.  

Scientists then looked at the digestive behaviours of two set milk gels (one firm and one soft) and the appearance of protein breakdown products (amino acids) in the blood finding that there were differences between the gels in the rate at which amino acids appeared in the blood. These clinical findings have implications for targeted product design for specific consumer groups, e.g. where there might be a need to deliver nutrients quickly (useful for athletes, for example) or slowly. 

An aligned study where data is currently being analysed has looked at the effects – digestive comfort, function, metabolism, physical activity and gut microbiota composition – of the consumption of goat, cow, and sheep milk powder. 

This study was funded by the High Value Nutrition National Science Challenge, developed and supported by three of the industry partners – NIG Nutritionals, Miraka and Spring Sheep Milk Co – with Otago University leading the clinical component.  

Meanwhile, the NZ3M consumer science team, led by Professor Joanne Hort, the Fonterra Riddet chair in Consumer and Sensory Science, and based at Massey University, has investigated wellbeing messaging that the targeted group of older Chinese adults will understand, believe and value.  

Six areas were explored including reviewing how well-being benefits are communicated to Chinese consumers in advertising and on-pack – a process that revealed a price premium charged for milks claiming higher dietary fibre, no added sugar and other health-related statements.   

To gather information on how milk is used by Chinese consumers, the team researched top selling cookbooks to identify recipes using milk as an ingredient, as well as viewing documentaries showing how milk is featured in different foods from specific regions. 

The consumer science team also gathered details about Chinese milk production, imports, consumption and relevant Chinese government policies. Included here was information on where there was no tradition of milk consumption, low engagement, the challenges associated with lactose malabsorption and the government’s encouragement of milk consumption. Also identified was the potential for opportunities around the lack of dairy product diversity as well as lactose tolerance.  

A special tool to identify and analyse the opinion of older Chinese consumers about milk products was developed by the team with the information generated being highly valuable for product development and marketing messaging. The tool can also be used across other product categories and market segments. 

The sixth component of the consumer science work was a comprehensive survey of 1,000 older Chinese people living in five different cities. Questionnaire topics covered included milk consumption habits and the purchasing of milk. Results showed that almost all survey participants consumed cow milk by drinking it at home. Although there were variations from city to city, most drank milk at breakfast time, with their family, and for nutrition and health purposes.  

The complex study, funded by the Ministry of Business, Innovation and Employment, led by the Riddet Institute, and supported by its 16 industry partners, has the goal of helping grow New Zealand’s milk sector by providing new knowledge of how different milks and processing influence digestive and nutritional outcomes. Alongside this, to provide fresh insights into the preferences and consumption of consumers in the valuable Chinese market.