[Defense de thèse] 18/12/23 : Adrien Servent - Rationalisation des conditions opératoires au cours de la transformation de fruits tropicaux pour maximiser les qualités sensorielle et nutritionnelle. Application to flash détente and tangential filtration (INRAE/UMR SQPOV)

Title of the thesis

Rationalisation of operating conditions during tropical fruit processing to maximise sensory and nutritional quality. Application to flash détente and tangential filtration

Date and place

Monday 18 December at 2pm in room PHIA
INRAE
UMR SQPOV
Domaine Saint Paul
228, route de l'Aérodrome
Site Agroparc - CS 40509
84914 Avignon Cedex 9

Discipline

Food science

Laboratory

UMR SQPOV / UMR QualiSud

Framing

• Thesis supervisors: Carine LE BOURVELLEC (DR) and Sylvie BUREAU (IR-HDR)

Composition of the jury

• Mrs Catherine RENARD (DR) - Rapporteur
• Mr Pierre PICOUET (PR) - Rapporteur
• Mr Patrick BOREL (DR) - Examiner
• Ms Marie-Noëlle MAILLARD (PR) - Examiner
• Manuel DORNIER (PR) - The Agro Institute - Guest
• Dominique PALLET (DR) - CIRAD - Invited
• Renaud BOULANGER (DR) - CIRAD - Guest

Summary of the thesis

This VAE thesis is based on a selection of work carried out over more than 13 years, in which I studied new sources of enriched ingredients derived from tropical and sub-tropical fruits. The feasibility and adaptation of the operating conditions of the processes have been considered in relation to the final use of the extract, as a natural antioxidant ingredient, colouring agent, emulsifier, flavouring agent, etc. I have chosen to present my work on flash release and filtration.

Flash-detente applied to mango and avocado enables the whole fruit to be transformed into a puree by recovering all the pulp, preserving the initial sensory quality (aroma, colour) and inhibiting the activities of the enzymes responsible for browning. In addition, it is possible to modulate the operating conditions to obtain products of different qualities, thanks to the transfer of compounds contained in the skin and kernels to the pulp. This allows purées, juices or extracts to be enriched mechanically using natural means, thus avoiding certain subsequent assemblies or formulations. For example, it may be chosen to maximise the extraction of potentially bioactive and antioxidant polyphenols from the inedible fractions by using drastic operating conditions to obtain a purée up to 6 times more concentrated for avocado and 35% more for mango, to the detriment of certain sensory aspects (flavour compounds, colours etc.).

Crossflow microfiltration makes it possible to produce carotenoid concentrates from apple-mahogany press cakes, an industrial co-product, up to concentration factors of 10 (or even higher) with viable performance on an industrial scale. In addition, it is possible to purify these extracts enriched in provitamin carotenoids relative to dry matter by high factors in return for an increase in process water consumption. Nanofiltration was applied to hydroalcoholic extracts of raspberry, olive pomace and margine and prickly pear juice in order to separate flavour compounds and polyphenols (in particular betalains and secoiridoids). Using the same process, and exploiting the differences in retention between the compounds, the retentate and permeate have variable qualities depending on the operating conditions. The extract can be concentrated, purified or fractionated depending on the end use of the products.

Combining these processes seems promising. However, the methods for incorporating these ingredients into foods still need further study, as does the determination of their health effects.