Ga. Gonzalezaguilar et al., TEMPERATURE AND DURATION OF WATER DIPS INFLUENCE CHILLING INJURY, DECAY AND POLYAMINE CONTENT IN FORTUNE MANDARINS, Postharvest biology and technology, 12(1), 1997, pp. 61-69
Late-ripening mandarin (Citrus reticulata, Blanco, cv. 'Fortune') is a
ppreciated for its quality, but the high sensitivity of this cultivar
to chilling injury (CI) limits its marketability. In this study, the e
ffect of postharvest hot-water dip (HWD) treatments on chilling tolera
nce and polyamine (PA) induction in flavedo tissue was investigated. A
fter HWD treatments (44 degrees C for 3, 9 and 15 min; 47 degrees C fo
r 3, 6 and 9 min; and 50 degrees and 53 degrees C for 3 min), fruits w
ere stored for 45 days at 2 degrees or 12 degrees C, and CI developmen
t, decay, weight loss, and PA content were evaluated. After 45 days at
2 degrees C, the major reduction in CI was found in fruit dipped for
6 min at 47 degrees C or 3 min at 53 degrees C. Under these treatments
, the CI index was 0.8 and 0.75, respectively, as compared with 1.5 in
untreated fruit. Fruit stored at 12 degrees C did not develop any CI
symptoms. The different HWDs also reduced fruit decay, bur did not alt
er the rate of water loss during cold storage at both temperatures. Im
mediately after HWDs, PA content increased in flavedo with temperature
and exposure time. The most important relative increase occurred in s
permine (spm), despite being the minor PA. The HWD-induced spm content
decreased about two-fold after 28 days of cold storage. Spermine redu
ction was more important than that observed in spermidine (spd) and pu
trescine (put). This pattern of change in PA content does not appear t
o be related to the HWD-induced cold tolerance. (C) 1997 Elsevier Scie
nce B.V.