Centre for Nuclear Sciences and Technologies

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Effect of gamma radiation on bioactive compounds of olive wastes

Publication . Madureira, Joana; Dias, Maria Inês; Barros, Lillian; Santos-Buelga, Celestino; Margaça, Fernanda M.A.; Ferreira, Isabel C.F.R.; Cabo Verde, Sandra

The olive pomace is an environmentally detrimental residue from olive oil industry. This residue contains large amounts of bioactive compounds, such as hydroxytyrosol and tyrosol, secoiridoid derivatives, phenolic acids and flavonoids1 that might be used by the food industry as preservatives. The aim of this work was to study the gamma radiation potential to improve the extractability of the bioactive compounds present in olive wastes. Gamma radiation is an eco-friendly technology that can be used to enhance the benefic properties of different agro-industrial products. Olive pomace samples (crude olive pomace - COP - and extracted olive pomace - EOP) were collected from UCASUL - União de Cooperativas Agrícolas do Sul, located in Alentejo region, in Portugal. The irradiation experiments were carried out at room temperature in a Co-60 semi-industrial facility (absorbed doses: 5-22 kGy; dose rate: 16 kGy/h). The characterization of the phenolic profile in the extracts of olive pomace and the identification of the radiolytic products were carried out by HPLC-DAD-ESI/MS2. The major phenolic compounds present in olive pomace extracts were hydroxytyrosol, hydroxytyrosol-1-β-glucoside, tyrosol, syringic acid and luteolin-7-O-rutinoside. Caffeic acid, vanillin, verbascoside and its derivatives and oleuropein aglycons were also found in the extracts although in lower concentrations. The obtained results demonstrated that gamma radiation significantly improved the extraction of phenolic compounds from both olive pomace extracts, obtaining the highest yield at 10 kGy for EOP and at 22 kGy for COP. At these doses, the total concentration of phenolic compounds in the extracts was 159±7 mg/g in the EOP and 161±2 mg/g in the COP ones. Comparing with non-irradiated samples, these values represent an increase in extractable phenolic compounds of 2.5 and 2.4 fold, respectively. Nevertheless, for EOP it was found that an absorbed dose of 5 kGy was capable to increase the phenolic content with no significant difference from the higher applied doses. These results demonstrated that gamma radiation could be a suitable technology for the valorization of olive oil by-products, contributing to enhance extraction of phenolic compounds. This outcome can help the olive oil industry to adopt clean processes and promote the sustainable development.

2019Conference object

Open access

Fostering E-beam food irradiation

Publication . Cabo Verde, Sandra; Antonio, Amilcar L.; Santos, Pedro; Redondo, Daniel; Teubib, Pamela; Falcão, António N.

There is an ever-increasing global demand from consumers for high-quality foods with major emphasis placed on quality and safety attributes. One of the main consumer demands is for minimally processed foods that are highly nutritive but low energy-dense and are natural foods with no or minimal chemical preservatives. Extending the shelf-life of food products, while improving the food safety and quality, will have a positive impact on both the industry and consumers. Food irradiation is emerging as a promising and innovative processing technology in this regard. The main objective of this research was to investigate and propose fresh irradiated foods that are health promoting, safe and convenient to be treated by electron beam irradiation. One of the purposes of this research is to help foster more wide use of electron beam irradiation especially where it will enhance food safety and quality. To attain these aims, electron beam irradiation parameters were studied in terms of equipment parametrization, as well as, the effects of irradiation on fresh food products through the evaluation of bioactive compounds and also microbial inactivation (natural microbiota and potential pathogenic bacteria). The food products selected for study were cherry tomatoes, raspberries, and mushrooms. These where chosen due to their perishability, nutritional and bioactive compound profile, and socioeconomic importance in the Mediterranean region. Modelling tools were also applied to simulate high energy electron beam irradiation (10 MeV) of cherry tomatoes and raspberries from the LINAC situated at C2TN (Portugal). An alternative simulation framework, Ensaroot, was also used to test its application in food irradiation studies. Overall the results of this comprehensive study support the feasibility of electron beam irradiation as a post-harvest treatment of cherry tomatoes (3 kGy), mushrooms (5 kGy) and raspberries (3 kGy). It would guarantee the safety, extend the shelf-life and preserving the bioactive contents of these products.

2022Conference object

Open access