Utilizing polyphenol-biopolymer interactions for structural design of food for diet and health

Polyphenols are widely distributed in nature, e.g. in fruit, vegetables, tea, and are responsible for major organoleptic characteristics, particularly colour and taste. As nutraceuticals, they are also reported to contribute to the health benefits associated with diets high in fruit and vegetables or plant-derived beverages. The interactions between plant polyphenols and biopolymers (e.g. proteins) - another abundant material in foods - are being intensively studied in relation to taste and stability of tea, wine and beer. These interactions usually lead to haze formation and/or precipitation due to formation of insoluble polyphenol-protein complexes. This uncontrolled process has a negative impact on several product functionality aspects (e.g. stability, appearance) and great efforts have been made to prevent it. The overall aim of the proposed research is to utilize physico-chemical interactions between natural polyphenols and biopolymers to design novel materials and complex colloidal dispersions for structuring food. The goal is to exploit these usually unwanted interactions and to use the resulting insoluble complexes to design structures and stabilise novel food products. Such structurally modified compositions will allow stable incorporation and active manipulation of the delivery of the nutraceutical benefit of plant polyphenols. The specific objectives are to identify appropriate polyphenol - biopolymer reactive systems which will be used to design structures such as simple fluid-in-fluid dispersions (e.g. emulsions) where the insoluble complexes are used as a protective layer (to encapsulate oil or water phases) or more complex multiple dispersions containing the insoluble complexes as a separate disperse phase. To achieve this we will rely on microfluidics technique in combination with confocal microscopy which allows real-time microscale control of physico-chemical interactions and formation of complex dispersions. These structures will be further characterised for stability in product and in physiologically relevant conditions. We propose to concentrate initial experiments on a known reactive system of flavonoids and proline-rich proteins. Based on a proof of principle for this system, it will be possible to extend the study to design other polyphenol-biopolymer systems. The scientific challenge will be to control the strength and nature - physical or/and chemical - of the polyphenol-biopolymer interactions, such that morphology, size and surface properties of the resulting structures can be optimised for specific applications. The innovative aspect of this research program is the utilisation of traditionally unwanted interactions between abundant plant biomolecules and the resulting materials for product design. Being edible, biocompatible and biodegradable, these materials will bring commercial benefits in several sectors, e.g., food and home and personal care products, animal feed, agriculture, pharma, and packaging materials. Applications include designing novel textures, controlling stability in products, and delivering polyphenol-based antimicrobials, antioxidants, UV-absorbers, and pigments.