Semi‐siccative oils and bioactive fractions isolated from Reunion Island fruit co‐product: two case studies

Abstract

This paper focused on the use of agro‐industrial wastes of strawberry guava (Psidium cattleianum) and passion fruit (Passiflora edulis) generated by the agricultural industry on Reunion Island, according to two routes: extraction of semi‐siccative oils from the seeds and extraction of bioactive compounds from residual pulp and peels. Oil content, fatty acid, carotenoids, tocopherol and sterol concentrations were determined in the seed oils obtained by four different extraction processes using Soxhlet extraction, extraction by hexane and ethanol, mechanical pressing and supercritical‐CO₂ (SC‐CO₂) extraction.. The oil extraction yields ranged from 15 to 30% w/w for strawberry guava and passion fruit, respectively. Mechanical‐pressed and SC‐CO₂ extracted oils were of satisfactory quality (low acid value, high carotenoid, sterol and tocopherol levels). Both oils were classified as semi‐siccative and had a similar total unsaturated fatty acid content (88%) with a prevalence of linoleic acid, accounting for 78% in strawberry guava and 70% in passion fruit. High contents in phytosterols and in α‐tocopherol were particularly detected in strawberry guava oil. The antioxidant activities of the bioactive compounds extracted by water and ethanol from pulp and peels were characterized by DPPH test. After purification on polymeric resin, significant antioxidant activities were recorded (IC₅₀ from 11 to 50 g/L) and were related to polyphenol contents (20.7 to 42.5 g GAE/100 g dry extract).

Practical applications: There is a great interest on the use of tropical fruit wastes because of their large availabilities. Strawberry guava and passion fruit are often used in the food industry, for juice and jam production. The seeds, pulp and peel residues are in fact a by‐product of their industrial processing, which should be valuably processed instead of just throwing away. We can state that the extracted seed (rich in polyunsaturated fatty acids) of strawberry guava and passion fruit can be used in the industrial production of emulsions, paints and varnishes. Within the positive aspects of the study, one can also distinguish the use of these tropical fruit by‐products as beneficial sources of many valuable bioactive compounds, e.g. carotenoids, tocopherols, phytosterols, and especially polyphenols, for functional formulations. Moreover, it may be the experimental basis for further development and use in food industry.

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