Effect of Freezing and Thawing on the Quality of Durian (Durio zibethinus Murray)
Produced in Southeast Asia
Araki Lab, Graduate School of Agricultural and Life Sciences, The University of Tokyo
Ueno Lab, Faculty of Education, Saitama University
Yoshie Lab, Faculty of Food and Nutritional Sciences, Toyo Uni
The effect of freezing, and iced and hot water thawing on the quality of durian pulp was investigated. Mature durian pulp was removed with seeds, vacuum-packed, and frozen at -20°C. Thawing in iced water and hot water (~90°C) was then applied and the quality of the pulp was assessed based on physicochemical properties (pH, moisture content, soluble solids concentration (SSC), color, sugar content (sucrose, glucose, and fructose), and organic acid content (succinic acid and citric acid)), texture and aroma profile. Overall, the freezing and thawing conditions, particularly the hot water thawing, posed an effect to the moisture content, color, and aroma profile of the durian pulp. A significant increase in the moisture content as well as a decrease in the color brightness were observed. Furthermore, the hot water-thawing process also induced variation to the aroma attribute. Although the sugar content significantly decreased after freezing and thawing, it was only affected by the freezing process but not by the thawing conditions. No significant variations were noted in the pH, SSC, organic acids and texture of the frozen durian pulp.
The preliminary effect of freezing and different thawing conditions on the physicochemical, textural, and aromatic attributes of durian was evident in this study. Overall, the freeze-thawing conditions have a significant impact on the moisture content, color, sugar content, and aroma profile of the durian pulp. The moisture content of the pulp increased while the brightness of the pulp color decreased significantly after hot water thawing. For the organic acid and sugar contents, generally, the sugar content was affected by the freezing process but not by the thawing conditions. The sugar content was significantly decreased after freezing and thawing. Furthermore, the aroma profile of the frozen and thawed durian pulp is generally affected by hot water thawing according to the PCA figure (Fig. 1). No significant variations were noted in the pH, SSC, organic acids and texture of the durian pulp after freezing and thawing. With these, the study is worthy of further investigation to provide relevant basic knowledge on the quality changes of durian after freezing and thawing, and to recommend appropriate cold storage condition for the durian pulp. Other thawing conditions in between iced and hot water can be explored to determine the condition under which the quality variations occur. In addition, literatures reported that variety and maturity could cause variation on the effect of freezing in the fruit, thus it would be also an interesting area to study for durian. Lastly, correlation of the quality changes to consumer sensory evaluation would also be relevant to the frozen durian industry.