Wj. Opperman et al., A monolithic device for in-package SO2 generation for the control of postharvest Botrytis decay of table grapes, J FOOD QUAL, 22(4), 1999, pp. 427-438
The occurrence of Botrytis cinerea and sulphur dioxide (SO2) bleaching on t
able grapes are the main causes for the deterioration of fruit quality duri
ng postharvest storage. Efficacy tests were conducted with novel monolithic
type devices which release SO2 at a constant rate over an extended period.
The devices comprise a polymer matrix, with sodium metabisulphite (Na2S2O5
) particles dispersed evenly throughout the matrix. Treatment combinations
consisting of various Na2S2O5 concentrations (10% to 50%) and number of dev
ices (2 and 4) placed amongst the grapes, were tested along with the inclus
ion or exclusion of paper liners, acting as barrier between the grapes and
the SO2 device. The efficacy of the new SO2 device was compared with the du
al release SO2 system. The new device reduced SO2 bleaching as result of lo
wer initial SO2 levels and the emission of lower levels of SO2 over an exte
nded period. Storage decay was also reduced with the use of the new devices
. The number of discs used within the carton, the concentration Na2S2O5 inc
orporated in the discs, and the use of corrugated paper liners, affected th
e proficiency of the devices. Decay control was more effective iri absence
of a liner than in its presence, while SO2 damage increased when the liners
were omitted. Reduced control was associated with the packaging treatments
where only two discs were included, or when devices of low Na2S2O5 concent
rations were used. Decay control was dramatically improved by increasing th
e Na2S2O5 concentration incorporated in the new polymer SO2 devices.