Relationship Between Jujube Cultivars And Dried Condition And Formation Of Bitterness In Jujube

Hami jujube,Jun jujube and Grey jujube were chosen as the experimental materials to be dried by heat pump drying under 45?, natural drying in the sun and drying in the shade. The changes of nutrients and anaerobic respiration metabolism-related enzyme activity were determined, the correlation between content of acetaldehyde, ethanol, fusel oil, furfural and amino acids and tatse of bitter jujube was analysed, the realationship between jujube cultivars and dry condition and formation of bitterness in Jujube was discussed. The conclusions followed as:1. The score of bitter taste was increased in three varieties jujube after dried. The score of bitter taste in Hami jujube and Jun jujube were higher than Grey jujube and natural drying was higher than heat pump drying under 45?. The index of texture various kinds of fresh jujube were significant differences in hardness, elasticity, gumminess, chewiness, that is say, itself brittle hard, internal bonding force between degree of tissue density, cell size were differences. The content of reducing sugar, total sugar, sugar acid ratio, total phenol, total flavonoids in three kinds of jujube were increased after dried, the content of total acid was declined. Jujube varieties and dried conditions had large impact on nutrients in jujubes.2. The changes activity of anaerobic respiration metabolism related enzymes were increased and then decreased to a certain stage of the loss of activity in three varieties of jujube under different dried conditions in the drying process. The activity of pyruvate decarboxylase and alcohol dehydrogenase activity in Hami jujube under the three kinds of dried conditions were higher than Jun jujube and Grey jujube, and the activity of ?-glucosidase of Grey jujube was higher than Jun jujube and Hami jujube.3. The fusel oil and furfural was not detected in three kinds of fresh jujube samples. The total content of fusel oil was significantly increased after dried. The total content of fusel oil in Hami jujube was higher than that of Jun jujube and grey jujube.The content of isoamyl alcohol and furfural had a greter influence on jujube flavor. The acetaldehyde and ethanol in three fresh jujube was in the lower level and the content of acetaldehyde and ethanol was accumulated to some extent after dried.But the same jujube varieties in different dried condition, there is no significant difference in content of acetaldehyde and ethanol after dried.4. Through the three varieties of jujube dried before and after the analysis of the amino acids, The conent of 17 kinds of amino acid in fresh three kinds of jujube as follows: Hami jujube > Jun jujube > grey jujube.The higher content of amino acids were the aspartic acid and proline in three varieties of jujube dried before and after. The content of the bitter total amino acids accounted for the total content of amino acid of 18.79% ~26.46%.The bitter score was significantly correlation of the content of bitter amino acid(R=0.785). The total content of bitter amino acid in Hami jujube and grey jujube had no significant difference(P > 0.05). Hami jujube and jun jujube, Jun jujube and Grey jujube had significant difference(P < 0.05).5. The taste of Hami jujube was more bitter than Jun jujube and Grey jujube, it was realationship of its own physical character and the activity of anaerobic respiration metabolism realated enzyme and the total content of fusel oil, furfural and bitter amino acid total content, therefore, jujube cultivars and dried condition had realationship on the formation of bitterness in jujube.