Whole grains have been a staple food for thousands of years, but nowadays most of the beneficial bioactive ingredients (mainly present in bran) are discarded in the production of good quality white flour.
But agri-food scientists have now developed technology to encourage millers to go back to their whole wheat roots using debranning, which limits the negative taste and texture impact that bran fractions have on whole wheat flour, while at the same time improving product efficiency and yield.
In traditional wheat milling, bran is removed at the washing, conditioning and breaking stages and the majority is then recycled as animal feed. With debranning (or pre-processing), 10% of the bioactive bran is methodically sheared from the endosperm to form fine uniform particles, which are reintroduced during milling to produce whole grain flour.
“The costs involved with debranning can be prohibitive and have prevented wide-scale implementation,” said Roberto Ranieri, founder and managing director of Open Fields, a small company dedicated to technology transfer and R&D for the food business.
“However, modern technology not only enables millers to produce added-value whole grain flour but also increase net flour yield, product quality and overall efficiency of the milling process. In the light of current health trends, we believe there will soon be sufficient demand to support production of whole grain flour on a much larger scale using debranning technology,” he told Milling & Grains.
Commercially viable three-step process
Ranieri and his team have developed a three-step process, particularly suited to durum wheat mills dedicated to the production of semolina, that has the potential to increase milling yield by up to 3% and milling capacity by up to 20%.
Three debranning machines progressively remove nutritionally rich bran fractions from the wheat kernel – the outer bran fraction with high dietary fiber, the intermediary fraction containing B vitamins, and the inner bran fraction rich in protein. In this way, the resulting whole grain flour has specific health properties, but the added bran does not adversely affect the taste and texture of the flour.
“Micronization reduces the bran to fine particles so that when it is incorporated into semolina or to flour, there is a significant reduction to the characteristic sandy texture and cardboard taste of found in many whole grain flours. The nutritional characteristics of the bran fractions are significantly increased using turbo-separation to select fractions with a higher nutrient or mineral content,” Ranieri said.
Debranning can also reduce levels of contaminants and mycotoxins present on the surface of the wheat kernel. This means that the affected outer layer of the wheat kernel can be used in flour production rather than mill feed.
Ranieri added: “Genetics and breeding are effective methods for producing tailor-made wheat varieties (i.e. white wheat) in order to develop attractive whole grain flour. Scientists will continue to exploit a range of grain milling technologies to improve the quality of bran fractions, including cryomilling, laser ablation and electrostatic fractionation, but at the moment debranning is the most commercially viable approach.”