Conduc

Tropentag 2005
Stuttgart-Hohenheim, October 11-13, 2005
Conference on International Agricultural Research for
Development

Effect of Storage Temperature on Thermal Properties of mango cv. Nam Dok Mai Si Thong
Rachit Suwapanicha and Methinee Haewsungcharernb
a

Institute of Postharvest Technology , Chiangmai University , Chiangmai 50002, Thailand
E-mail: kcrachit@kmitl.ac.th

bDepartment of Food Engineering, Faculty of Agro-industry, Chiangmai University, Chiangmai 50100, Thailand
E-mail: methinee@chiangmai.ac.th

Abstract
Mango fruit cv. ‘Nam Dok Mai Si thong’ (Mangifera indica L.) harvested at fully mature-green
stage were stored at 5, 13 and 25 ±2 °C. The specific heat and thermal conductivity of mango
flesh during storage were determined by Modulated DifferentialScanning Calorimeter (MDSC)
followed ASTM-E1952 –98 method. The results shown that the specific heat of mango flesh
stored at 25 ± 2 °C increased in the first 2 days of storage, and remained constant thereafter,
whereas those of the ones stored at 13 °C and 5 °C were relatively constant during 25 days of
storage (p ≤ 0.05). Thermal conductivity of mango flesh, on the other hand, decreased in 5days
when stored at 13 °C, and increased rapidly afterward. The similar results were found in the fruit
that stored at 25 ± 2 °C, however, the thermal conductivity of mango flesh which stored at 5 °C
increased in the first 5 days and remained relatively constant during 25 days of storage. The
electrolyte leakage of mango flesh showed the similar results with the thermal conductivity forwhatever storage temperatures. Chilling injury became visible as pitting and discoloration after
5 days and 20 days held at 5 °C and 13 °C respectively. The electrolyte leakage of mango flesh
stored at 13 °C increased continuously but that of 5 °C was relatively constant. Since electrolyte
leakage is one of the indicator that being used to determine the chilling injury and the ripening
process,the increasing of electrolyte leakage as well as thermal conductivity in the case of 13 °
C might be due to chilling injury incorporated with ripening process. It was possible that the
thermal conductivity of the fruit could be related to chilling injury symptom and ripeness.
1. Introduction
Mango (Mangifera indica Linn.) is one of the important economic fruit crops in Thailand, and
Thailand isone of the major producers and exporters of mango. With an increasing demand and
increased percentage of mango fruits being exported aboard, its storage life is a major concern.
After harvest, fruits and vegetables including mango remain alive and normal life process
continue. The life processes can be controlled to a certain extend by low temperature storage
(Moshenin, 1980; Wills et al.,1981). When mango being stored at low temperature for a period
of time, there is the risk of physical changes due to chilling injury. The symptoms of chilling
injury are either surface pitting, discoloration, internal breakdown or decays (Kader, 1992 and
Mitra and Baldwin, 1997). It has been shown that the chilling injury is initiated by a thermally-

induced transition in the structure orphase state of some lipids which constitute the bilayers of
cell membrane (Raison and Orr, 1986). Since the thermal properties are also related to the phase
transition within a fruit (Aggarwal, 2000, Yahia and Dominguez ,1995) they might be used as an
indicator of the chilling injury. The objectives of the study are to determine the effect of storage
temperature on thermal properties of mangofruit and to relate these properties to the chilling
injury.
2. Material and Methods
Exported graded mangoes cv. ‘Nam Dok Mai Si Thong’ obtained from an orchard in
Chachoengsao province, Thailand, were used in this experiment. Fruits were selected by
uniformity of shape, color and size. The blemished or infected fruits were discarded. The storage
temperature were 5, 13 and 25±2 °C.
2.1...