JIA-2019-11

2517 Maratab Ali et al. Journal of Integrative Agriculture 2019, 18(11): 2514–2520 The pattern of change in T-AsA content in the kiwifruit was similar to AsA content, and T-AsA content in OA pre- treated kiwifruit also significantly higher than that in the control during storage (Fig. 2-C). The AsA/DHA ratio in OA pre-treated kiwifruit decreased gradually, while in the control it remained stable for the first 4 d, after which it dropped and slightly declined to 13 d of storage. However, a significantly higher AsA/DHA ratio was found compared to the control during whole storage of 13 d (Fig. 2-D). 3.3. Effect of pre-harvest OA treatment on contents of endogenous OA and tartaric acid in harvested kiwifruit Endogenous OAcontent of kiwifruit gradually increased to a peak on the 10th d and then decreased, and a significantly higher OAcontent in OA treatment on the 10th d with respect to the control ( P <0.05) (Fig. 3-A). The tartaric acid content in OA pre-treated kiwifruit slightly increased to 4 d of storage, after which it dropped and then remained stable from 7 to 13 d of storage, while in the control it almost remained stable during whole storage of 13 d. Thus, compared to the control, a significantly higher content of tartaric acid in the pre-harvest OA treatment was observed during the first 4 d of storage (Fig. 3-B). 3.4. Effect of pre-harvest OA treatment onmetabolism of ethanol in harvested kiwifruit The acetaldehyde and ethanol contents showed a slight change until the 7th d in both control and treated fruit, and then in the control they increased sharply to a peak on the 10th and 13th d, respectively, whereas in OA-treated fruit acetaldehyde and ethanol contents increased gradually for the remainder of the storage time. Thus, the contents in OA-treated fruit were significant lower than that of the control from d 10 to 13 (Fig. 4-A and B). The pattern of change in PDC or ADH activity in both control or OA pre-treated fruit was similar during storage, which showed that PDC activity remained at a relatively steady level during the first 7 d of storage, and then it sharply increased and remained at a steady high level for the rest of the storage period; while ADH activity increased gradually to the maximum on the10th d and then decreased during the remaining days. However, significantly lower levels of PDC andADH activity were presented in the OA-treated fruit from d 10 to 13 compared to the control (Fig. 4-C and D). 4. Discussion In fruit, the contents of SSC and TA generally account for assessment of fruit ripening stage along with nutritional Storage time (d) Storage time (d) * * * * * 0 20 40 60 1 4 7 10 13 A * * * * * 0 20 40 60 80 1 4 7 10 13 C * * * * * 0 10 20 30 40 1 4 7 10 13 D 0 1 2 3 1 4 7 10 13 B CK 5 mmol L –1 oxalic acid AsA content (mg 100 g –1 FW) T-AsA content (mg 100 g –1 FW) DHA content (mg 100 g –1 FW) AsA/DHA rate Fig. 2 Effect of pre-harvest oxalic acid (OA) treatment on ascorbic acid (AsA; A), DHA (B), total-AsA (T-AsA; C), and AsA/DHA ratio (D) in kiwifruit during storage at room temperature. Data were the means of three replicates±SD.