THE USE OF NATURAL AROMATIC ESSENTIAL OILS HELPS TO MAINTAIN POST-HARVEST QUALITY OF ´CRIMSON´ TABLE GRAPES

‘Crimson’ table grape clusters were packaged on trays and then sealed with polypropylene bags to generate a modified atmosphere. Hence, a sachet impregnated with either 0.5 mL of thymol or 0.5 mL of menthol was included outside the tray. Thus, volatile compounds were released to the headspace package acting as active substances. Then, packages were stored at 1°C and 90% RH for 35 days. Samples were taken weekly for analytical determinations: atmosphere composition inside the bags, weight loss, °Brix-titratable acidity ratio, colour evolution and fruit firmness. Also, the visual aspect of the rachis and quantification of both total yeast and mould and mesophilic aerobic were performed. Steady state atmosphere was reached at day 21 of storage with 1.2-1.3% of CO₂ and 13-14% of O₂, with no significant differences between treatments and control. However, both treatments showed significant lower weight loss and °Brix-titratable acidity ratio than controls during storage. These different conditions of packaging and storage also delayed the colour changes and fruit firmness. Thereafter, the microbial analysis showed that both essential oils reduced yeasts, moulds and total aerobic mesophylic colonies by 3-log CFU, and also improved the visual aspect of the rachis. These natural compounds could be an alternative to the use of SO₂ in table grapes, since they showed improvements of the fruit shelf life in terms of quality and incidence of decay, one of the most important problems during commercialisation of table grapes.