Most of the losses that happen after harvesting are due to a variety of factors such as fungal and microbiological infections, physiological disorders and physical damage. Produce that is particularly perishable is kept at low temperatures and harvesting is finished at the place of destination in favourable conditions. Prolonged storing at low temperatures though leads to an inferior quality than that of fruit that ripens normally.
Various technologies have been used so far to extend shelf-life, such as modified atmosphere packaging and UV-B and ozone radiation.
One of the most recent methods being experimented is biofilms. Covering produce with semi-permeable and edible films slows down the ripening process and modifies CO2, endogenous O2 and ethylene levels, slowing down oxidation, extending shelf-life, diminishing the loss of bioactive compounds such as carotenoids, flavonoids, isoflavonoids and phenolic acids. In addition, biofilms can seal small cracks on the surface, delaying dehydration and microbial growth.
| Control | chitosan + bixin |
Through a project financed by the Brazilian government, a research group led by prof. Ranieri of the Agricultural, Food and Agro-environmental Sciences Department of the University of Pisa experimented the use of waste material such as collagen and chitosan to cover some fruit with the aim of employing the industry's by-products and improving quality during storing.
Chitosan biofilms were also used as effective carriers of many functional ingredients such as antimicrobial agents and antioxidant molecules that can improve the quality of food. In the experiment conducted in Pisa, bixin, with a considerable antioxidant power, was added to the chitosan. The results obtained showed how the tomatoes covered with the biofilm had 16% more lycopene, 39% more ß-carotene, 9% more phenols and 24% more flavonoids after 14 days. Tests are currently being carried out to study the aromatic profile of the tomatoes.
For further info:
Prof. Annamaria Ranieri
Dipartimento di Scienze Agrarie, Alimentari e Agro-ambientali
Università di Pisa
Via del Borghetto 80
I-26124 Pisa
Tel.: (+39) 050 2216605
Email: anna.maria.ranieri@unipi.it