New Processing Techniques Improve Gluten-Free Foods

CORK, IrelandEnzyme technology, bioprocessing and high-pressure processing technology have been successfully applied to improve the quality, safety and nutritional attributes of gluten-free cereal products developed for patients with Celiac disease.

Due to the unique properties of gluten, it is a big challenge for food scientists to produce good quality gluten free products. The majority of products currently on the market are in general of very poor quality; therefore, part of the European Unions HEALTHGRAIN project focused on the development of nutritious and tasty gluten-free breads.

The areas covered during the project were a detailed characterization of gluten-free cereals and the assessment of the cereals as potential ingredients for gluten-free breads. The characterizations ranged from a detailed chemical characterization to rheological evaluation of the resulting doughs, structural properties of the doughs and breads using advanced microscopic methods as well as pilotscale baking trials and sensory evaluation. Novel methods to improve the quality of gluten-free cereal products were also covered; one example being the use of specially selected lactic acid bacteria with properties such as antifungal activity, exopolysaccharide production and enzyme production. The use of specifically selected lactic acid bacteria can significantly improve the quality and shelf-life of gluten-free breads.

A major problem associated with gluten-free products is texture; therefore, part of the project was to investigate the influence of a range of enzymes such as transglutaminase, glucose oxidase and protease on wide range of gluten-free cereals. It was shown that enzymes can play an important role in improving the structure of gluten free bread, but the enzymes showed different interactions with the various gluten-free flours.

Novel processing such as high-pressure processing was also introduced as a means to create ingredients for gluten-free cereal products. The impact of HP was investigated on the major polymers found in gluten-free flours, such as starch and protein also was performed. The results revealed that starch gelatinization and protein network formation at pressures 350 MPa was obtained while a weakening of protein structures was observed at lower pressures. Addition of HP-treated gluten free batters to bread resulted in improved volume and decreased staling at 200 MPa, while higher pressures did not improve oat bread quality.