Technology of cereal foods digestibility

“To explore the potential of nature to improve the quality of life” is the mission of WUR (Strategic Plan 2015-2018). Sustainable production and processing of food, food safety and health aspects of food belong to the focus areas to achieve this mission. Starchy staple foods nourish the world population. Cereals are the main source of these staple foods.
In cereal based foods some issues reduce the food safety and security:
1. Coeliac disease has not been solved and patients have limited acces to palatable high quality gluten free food
2. The control of digestibility of cereal based products and its effect on nutritional status (undernutrition, obesity) is still limited
3. Non gluten wheat intolerances seem to be increasing, causing a decrease in consumption of cereal based products

Description of theme

The research on technology for regulated digestibility of cereal based foods will focus on three main issues:

  1. Anti nutritional factors in cereals, especially amylase trypsin inhibitors (ATI), affecting digestibility
  2. Starch digestibility in intermediate moisture foods
  3. Safety and quality of gluten free foods

1. Anti nutritional factors in cereals, especially amylase trypsin inhibitors, affecting digestibility

Anti nutritional factors (ANF) play an important role in cereals to protect against infestation and animal consumption. From an agronomic point of view these pest barriers are beneficial as the required pest control measures (chemical pesticides, storage facilities) is relatively limited.

From a health point of view a large group of ANF, the ATI are of special interest as they may impact digestion in multiple ways, e.g. they:

  • can reduce digestibility of food directly by inhibition of enzymes from the digestive tract (human and microbiome; Weegels 1994),
  • can increase the load of allergenic peptide presented to the small intestine, thus increasing the allergenic and inflammation reactions (Junker et al. 2012; Zevallos et al 2014)
  • complexation behavior may strongly interact with the small intestine epithelium that can cause inflammation by itself (Zevallos et al 2014)
  • are the not yet completely understood cause of Bakers asthma, the major labour related allergy (Stobnicka and Górny, 2015)
  • can increase the load of non digested peptides and carbohydrates especially of non-starch polysaccharides (FODMAPS) that are a major cause of Irritable Bowel Syndrome (IBS) which affects 7% to 21% of the general population (Chey et al 2015)
  • may impact the microbiome itself. This is not established in detail

From a food processing point of view ATI’s play a negative role as they inhibit enzymes that are added as processing aids for improved processing and bread quality. This reduces processing effectiveness and quality control of cereal based products.

Understanding the role of ATI in cereals food processing and food digestion and mitigation of the negative effects is therefor of prime importance for food safety, security and sustainability.

An interesting way to mitigate the effect of ATI could be by altering its molecular structure that is stabilised by the large number of disulphide bonds (5-6 on ca. 14 kDa; Buchanan et al 1997).

2. Starch digestibility in intermediate moisture foods

Starch structuring during processing and storage is key to food structure, its digestibility and palatability. the changes in crystallinity in starch during and after processing are another important factor determining the digestibility of cereal foods. These changes are depending on several factors:

  • Processing (time, temperature, heat transfer)
  • Food composition (a.o. presence of proteins, non-starch polysaccharides and components forming molecular complexes with starch like lipids)
  • Moisture content
  • Storage time and temperature after preparation

The speed of digestion of starch is linked to blood glucose levels and satiety and probably other health aspects, like obesity and cardiovascular diseases. It is, therefore, important to understand the effect of processing conditions on starch crystallinity and consequently the speed of digestion.

Most starchy staple foods are produced under low or medium moisture contents, such as baking, cooking, frying, extrusion, moulding, drying/puffing. Therefor focus will be on intermediate moisture foods.

3. Safety and quality of gluten free foods

This theme is principally concerned with:

a.             Improving the safety and safe use of cereals in relation to celiac disease, by improved analytical methods to detect toxic epitopes (van den Broeck et al 2010)

b.             Enabling the development of gluten-free bread by replacing gluten with other ingredient functionalities (van Riemsdijk, 2015)

References:

van den Broeck, H.C., de Jong, H.C., Salentijn, E.M.J., Dekking, L., Bosch, D., Hamer, R.J., Gilissen, L.J.W.J., van der Meer, I.M., and Smulders, M.J.M. 2010. Presence of celiac disease epitopes in modern and old hexaploid wheat varieties: wheat breeding may have contributed to increased prevalence of celiac disease. Theoretical and Applied Genetics 121:1527-1539.

Buchanan, B. B., Adamidi, C., Lozano, R. M., Yee, B. C., Momma, M., Kobrehel, K., Ermel, R. and Frick, O. L. 1997. Thioredoxin-linked mitigation of allergic responses to wheat. Proceedings of the National Academy of Sciences, 94: 5372-5377.

Chey, W.D., Kurlander, J. and Eswaran S. 2015. Irritable Bowel Syndrome. A Clinical Review. Journal of the American Medical Association 313:949-958

Stobnicka, A. and Górny R.L., 2015. Exposure to flour dust in the occupational environment, International Journal of Occupational Safety and Ergonomics  21: 241-249.

van Riemsdijk, L. E., van der Goot, A. J., Hamer, R. J. and Boom, R. M. 2011. Preparation of gluten-free bread using a meso-structured whey protein particle system. Journal of Cereal Science, 53: 355-361.

Weegels, P.L. 1994. Depolymerisation and re-polymerisation of wheat glutenin during dough processing and effects of low Mr wheat proteins, PhD Thesis, University of London, UK.

Zevallos, V. F., Raker, V., Maxeiner, J., Khan, M., Steinbrink, K., & Schuppan, D. 2014. A diet containing wheat alpha-amylase/trypsin inhibitors (ATIs) promotes allergic airway inflammation in mice. Zeitschrift für Gastroenterologie 52(08), FV44.