Studies On The Senescence Characteristics And Avenues Of Ethanol Accumulation Of Harvested "Dongzao Jujube"

Dongzao jujube fruit was a typical fresh fruit, the affluent in nutrition and crisp high quality were welcome to everyboby. But after harvest, Dongzao jujube fruit was inclined to lose water and crimpled, with softening, rotting and Vitamin C loss, the nutrition, the high quality and commodity value were not maintained because of its connatural characteristics of biology and physiology. At present, the problem of keeping-fresh for Dongzao jujube fruit was not resolved, which affected the development of Dongzao jujube fruit greatly. In this paper, its physiological characteristics in consenescence, accumulate ethanol avenues, and ultrastructure in flesh structure of Hebei huanghua's Dongzao jujube fruit were studied, The main results were as follows:1. The study on the respiration of Dongzao jujube fruit in the room temperature showed that the distinct respiration peaks were not found after harvest, therefore, this test material belonged to non-climactic fruit.2. The firmness of Dongzao jujube fruit was declined with the delay of storage time. On the whole, the titratable acid content as respiration substance which was declined, totle sugar content was increased temporarily in the prophase of its storsge, and declined gradually in the anaphase of its storage, but the reducing sugar was increased in the whole storage. Vc content was declined, the changes in Vc content was positive correlated with the firmness of Dongzao jujube fruit significantly (r=0.916). ethanol content accumulated continually, and reached higher level when it was consenescence. The changes of enthanol content was negative correlated with the firmness of Dongzao jujube fruit significantly (r=-0.968). The changes in Vc content was negative correlated with the changes of enthanol content significantly (r=-0.953). MDA content increased gradually, the changes of MDA content was negative correlated with the firmness of winter jujube fruit significantly (r=0.9107).3. The activity of PG changes were not correlated with the firmness of Dongzao jujube fruit after harvest significantly (r=0.646). The activity of PPO was increased gradually with the fruit's maturity, the activity of PPO changes was negative correlated with the firmness of Dongzao jujube fruit significantly (r=-0.833). The activity of POD reached top point with storage, The activity of POD was not correlated with the firmness of Dongzao jujube fruit after harvest significantly (r=-0.503). The activity of AAO increased rapidly with the decreaseness of Vc content. The activity of AAO was negative correlated with Vc content significantly (r=-0.955). The activity of AAO was negative correlated with the firmness of Dongzao jujube fruit after harvest significantly (r=-0.891).4. The pyruvic content changes was positive correlated with the acetaldehyde content changes significantly during respiring without oxygen (r=0.928). The main reasons of ethanol accumulation was the pyruvic and acetaldehyde content changes.The lignin in flesh content increased gradually, the activity of PAL which influenced the lignin in flesh content increased first, and then decreased, the activity of PAL led to lignin content rise. The lignin in flesh content was positive correlated with enthanol content significantly (r=0.967). Therefore, it was conjectured that the lignin in flesh content changes were important during ethanol accumulation.Observing the tissue of pericarp which were healthy and senile with the optical microscope, the results showed that the color of pericarp reddened, the cell structure was not tight, the intercellular space largened and much crack was found easily, so it was conjectured that a lot of collective microzyme in the softening tissue of Dongzao jujube were found because of the flesh structure changes, that led to enthanol accumulation.5. The interior structure of cell wall destroyed during maturity of the fruits, the cell wall and cell content decreased and changed fitful filiform substance. Middle lamella disapeared, decreased and changed filiform substance, the interstice was found easily and intercellular space largened. Those changes arose the flesh structure changes, and led to softening and consenescence in flesh.