Firmness and Decay of Apples following Postharvest Pressure Infiltration of Calcium and Heat Treatment

Abstract

Heating `Golden Delicious' apples (Malus domestica Borkh.) for 4 days at 38C or pressure-infiltrating them with a 4% CaCl 2 solution reduced decay and maintained fruit firmness during 6 months of storage at 0C. Heating reduced decay caused by Penicillium expansum Link ex Thorn by ≈30%, while pressure infiltration with CaCl 2 reduced decay by >60%. Pressure infiltration with CaCl 2 after heating reduced decay by ≈40%. Pressure infiltration maintained firmness best (>84 N), as measured with a manually driven electronic fruit-firmness probe, followed by heat and CaCl 2 (76 N), heat alone (71 N), and no treatment (control) (60 N). Force vs. deformation (FD) curves from a puncture test with a fruit-firmness probe mounted in a universal testing machine showed that fruit heated before storage were firmer than all nonheated fruit, except those pressure-infiltrated with 4% CaCl 2 . However, FD curves also showed that apples pressure-infiltrated with 4% CaCl 2 differed quantitatively from apples in all other treatments, including those heated.