Roller milling is a modern method of flour production that has largely replaced traditional stone milling since its introduction in the late 19th century. In roller milling, grains pass through a series of steel rollers, which crush and separate the bran and germ from the endosperm. The endosperm is then ground into fine white flour. For bakers interested in producing healthier bread, understanding the differences between roller-milled white flour and stoneground flour is crucial. While roller-milled flour offers convenience and longer shelf life, it is nutritionally inferior, impacts blood sugar levels more significantly, and fails to support gut health effectively. Stoneground flour retains more of the grain’s natural nutrients and fibre, making it a healthier choice for both bakers and consumers.
Understanding Roller-Milled White Flour: Process, Health Impacts, and History
The Roller Milling Process
The process involves:
- Cleaning: Removing impurities from the grains.
- Conditioning: Moistening the grains to toughen the bran and mellow the endosperm.
- Breaking: Passing the grains through rollers to crack them open.
- Sifting: Separating the broken grains into different components.
- Reducing: Further grinding the endosperm into fine flour.
Health Impacts of Roller-Milled White Flour
Roller-milled white flour is less healthy than stoneground flour for several reasons:
- Nutrient Loss: The bran and germ, which contain most of the fibre, vitamins, and minerals, are removed during roller milling. This results in white flour that is nutritionally inferior to wholemeal or stoneground flour.
- Blood Sugar Spikes: The fine texture of roller-milled white flour leads to a higher glycaemic index (GI), causing quicker spikes in blood sugar levels compared to the coarser, more fibrous stoneground flour.
- Broken Matrix: The process of roller milling breaks down the natural matrix of the grain. This impacts the body’s ability to digest the flour slowly, leading to rapid absorption of glucose and thus higher blood sugar levels.
- Gut Microbiome: Fibre from the bran is essential for gut health. The removal of the bran in roller-milled flour deprives the gut microbiome of necessary nutrients, affecting overall health and immune function.
A Short History and Fortification in the UK
The advent of roller milling in the late 1800s revolutionised flour production by making it more efficient and allowing for the mass production of fine white flour. However, the removal of the bran and germ led to significant nutrient loss. To combat this, the UK introduced flour fortification in the 1940s, requiring the addition of iron, calcium, and B vitamins (thiamin and niacin) to white flour. Despite fortification, roller-milled flour remains less nutritious than its wholemeal counterpart.
Advantages in Storage and Impact on Ultra-Processed Bread
One advantage of roller-milled white flour is its extended shelf life. The removal of the oily germ prevents rancidity, making it easier to store for long periods. However, this convenience comes at the cost of nutritional value.
Roller-milled white flour underpins the production of ultra-processed bread. The broken matrix and fine texture result in dough that can be more open and airy in sourdough bread, but the overall nutritional profile of the bread is significantly diminished. Ultra-processed bread often contains additives and preservatives to enhance texture and shelf life, further detracting from its health benefits.
