Edible coating composed of chitosan and Salvia fruticosa Mill. extract for the control of grey mould of table grapes

BACKGROUNDConsumer concerns regarding high-quality produce, free of pesticide residues, direct research towards disease management strategies that minimise or even exclude the use of synthetic chemistries in crop production. The efficacy of a chitosan-based edible coating combined with the acetonic extract of Salvia fruticosa Mill. (ASF) was assessed against the grey mould of table grapes. RESULTSHPLC-SPE-NMR and q-NMR analyses defined major constituents of ASF to be the flavonoids hispidulin, salvigenin and cirsimaritin and the diterpenes carnosic acid, carnosol and the 12-methoxycarnosic acid. The extract was found to be efficacious in reducing spore germination and mycelial growth of Botrytis cinerea in vitro at 10 and 25 degrees C. However, the combination of the ASF with chitosan 1% (w/v; CHIT) significantly improved fungal inhibition. Similarly, in fruit inoculation trials at 10 degrees C, the efficacy of the combined application of the ASF at 500 mg L-1 with CHIT against grey mould was statistically equal to the synthetic fungicide thiabendazole, ranging from 98.4% to 92.7% at 12 and 21 days post-inoculation, respectively. Furthermore, chitosan coating alone and in combination with ASF decreased the rate of fruit weight loss during cold storage, while preserved soluble solids content and titratable acidity. Chitosan-based coatings did not affect quality attributes and the bioactive compounds in table grapes. CONCLUSIONThe combined application of the ASF in the form of an edible coating with chitosan could effectively control B. cinerea without deteriorating quality and physico-chemical properties of grapes. (c) 2016 Society of Chemical Industry