VACUUM INFILTRATION OF POLYAMINES INCREASES FIRMNESS OF STRAWBERRY SLICES UNDER VARIOUS STORAGE-CONDITIONS

Strawberry slices were vacuum infiltrated with polyamines and changes in firmness during storage were determined. Spermine and spermidine at 10 mM or 100 mM significantly increased firmness, whereas putrescine was not as effective at increasing firmness of slices stored at 1-degrees-C. The firming effect of the polyamines was similar to that of calcium chloride, and may have been due to their ability to bind to cell walls and membranes. In ripe receptacles of various cultivars which differed in firmness, putrescine (12-38 nmol/g fresh weight) and spermidine (19-33 nmol/g fresh weight) were the predominant polyamines, while only low levels of spermine (< 10 nmol/g fresh weight) were present. There was no discernible relationship between endogenous polyamine levels and fresh fruit firmness for the cultivars studied.