Abstract
This study was conducted to compare differences in fruit quality by harvest time of 'Fuji' apple fruit that was frozen on tree by unusual low temperature in that air temperature was under $-3.5^{\circ}C$ for 7 hours. Fruits were harvested at 1 day before, and 2 days and 6 days after freezing damage, respectively. Harvest's soluble solid contents in all treatments was over $14^{\circ}Bx$. Firmness and titratable acidity of fruit harvested after freezing damage was lower than those of fruit harvested before freezing damage. During cold storage, ethylene production of fruit harvested after freezing damage was higher than that of fruit harvested before freezing damage. The reduction in the level of fruit quality during cold storage of fruit harvested after freezing damage was more serious than that of fruit harvested before freezing damage. The reduction of fruit quality during subsequent ambient temperature for 1 week after cold storage of fruit harvested after freezing damage was higher than that of fruit harvested before freezing damage. In comparison of treatments that were harvested at different times after freezing damage, ethylene production and reduction in the level of fruit quality until 8 weeks of cold storage of fruit harvested at 6 days after freezing damage was lower than that of fruit harvested at 2 days after freezing damage. However, this difference by harvest time after freezing damage disappeared after 8 weeks of cold storage. Incidence of flesh browning was not affected by freezing at air temperature under $-3.5^{\circ}C$ for 7 hours.
본 시험은 이상저온($-3.5^{\circ}C$ 이하에서 7시간 지속)에 의해 수체 상에서 동결된 사과 '후지' 과실들의 수확시기에 따른 품질차이를 비교하고자 실시하였다. 수확 시기는 동결피해 1일 전, 동결피해 2일 후, 동결피해 6일 후였다. 시험에 조사된 과실들의 수확시 가용성 고형물 함량은 $14^{\circ}Bx$ 이상이었다. 동결피해 후 수확한 과실의 수확 시 경도 및 산 함량은 동결피해 전에 수확한 과실보다 낮았다. 저온저장 중의 에틸렌 발생량은 동결피해 후 수확한 과실이 동결피해 전에 수확한 과실보다 높았다. 동결피해 후 수확한 과실의 저온 저장 동안의 품질저하는 동결피해 전에 수확한 과실보다 심하였다. 동결피해 후에 수확한 과실의 저온저장 출고 후 실온 1주일째의 품질 저하는 동결피해 전에 수확한 과실보다 더 심하였다. 동결피해 후에 수확한 시험구들간의 비교에서는 저온저장 8주까지 동결피해 6일 후에 수확한 시험구의 에틸렌 발생량 및 과실품질 저하가 동결피해 2일 후에 수확한 시험구보다 낮았으나, 이러한 차이는 저온저장 8주 이후로는 없었다. 과육 갈변증상 발생률은 $-3.5^{\circ}C$ 이하에서 7시간 동결될 경우 영향을 받지 않은 것으로 나타났다.
