Food Technology

Nesrine Ben Hadj Youssef is a Food Science Engineer. She is currently in her final year of PhD at University of Technology of Compiegne, France, where she is working on the encapsulation of antioxidants for food enrichment. She has participated in several scientific meetings in the field such as the 10th training school on microencapsulation, Sep’ 2018, Trondheim, Norway. She was selected for the ‘Three minute thesis’ regional final, Apr’ 2017, Paris, France.

Betacyanins are red beetroot (Beta vulgaris) pigments that have a growing interest due to their high antioxidant capacity, preventing several diseases such as cancer and diabetes. They are thus promising candidates to conceive food products with enhanced health-promoting properties. However, betacyanins are unstable when exposed to light, high temperature, high water activity and low pH. The aim of this work is to encapsulate the pigments to protect them from unfavourable conditions that occur during the fabrication process of food products and digestion. A betacyanin-enriched extract was obtained from raw beetroots using a food-grade process and spray-dried with several food-grade biopolymers: soy proteins, pea proteins and polysaccharides such as arabic gum, maltodextrin, alginate and chitosan. Physico-chemical studies were conducted to characterize the betacyaninenriched extract (degree of purity, water activity, protein, polyphenol and carbohydrate contents) and the spray-dried powders (morphology, particle size, water activity, moisture). The effect of encapsulation on the antioxidant capacity of betacyanins was studied as well as their release in digestive conditions. The results showed that the spray-drying yields and encapsulation efficiencies were superior to 50% for all the tested biopolymers. In addition, no loss in betacyanin antioxidant capacity was found upon spray-drying for most biopolymers. Pea proteins, soy proteins and alginate microcapsules showed a lower release rate in acidic conditions compared to neutral pH conditions. They can thus be good promising biopolymer candidates to encapsulate and stabilize betacyanin compound using spray-drying and to protect it from acidic food products and stomach conditions. We thus find that such microcapsules are interesting functional additives to enrich food products with health benefits.