Changes Of Nutrient And Functional Property Of Jujubes During Explosion Puffing And Study On Jujubes Proanthocyanidins

Jujubes is known as a medical and edible dual-purpose fruit in China,which is rich in nutrients and bioactive compounds,and has great potential for exploitation.Fresh jujubes deteriorate easily within a few days after harvest,and processing its products is necessary.The changes of nutrients and bioactive compounds during explosion puffing process were also monitored in the present work.This study can provide data support for the application of explosion puffing in jujubes.The structure identification of proanthocyanidins has not yet reported.In this study,the selection of raw material is pear-jujube,the changes of nutrient and fuctional properties during explosion puffing were investigated.The structure of the proanthocyanidins isolated from jujubes peel and pulp were characterized in this study.The main results of the study were as follows:(1)The content of reducing and total sugar were decreased during explosion puffing.The level of reducing and total sugar ranged from 22.96 to 28.56%and 28.38 to 36.78%,respectively.Three soluble sugar including fructose,glucose,sucrose and four organic acid including L-malic acid,citric acid and succinic acid were identified in pear jujube.(2)The marked change in total phenolic and total flavonoids contents is obvious during explosion puffing.A significant increase in the content of total phenolic was noticed in explosion puffed jujubes compared to fresh counterparts.Its content was significantly reduced after sun-drying treatment.The puffed jujubes showed stronger antioxidant quality than sun-dried fruits.Seven phenolic acids phenolic compounds were dectected in fresh fruits.The results indicated that the distribution and contents of phenolic compounds were changed after each treatments during explosion puffing.(3)In our PCA,the distance between each treatment relative to fresh fruit in the score plot space was calculated.The results indicated that distance in increasing order was occurred during explosion puffing.The changes of nutrients and bioactive compounds along with each treatments during puffing is matched basically with the real practice.The figure shows that explosion-puffing is closer to fresh jujubes than sun-drying.The results indicated that explosion-puffing is a excellent drying technique.(4)Statistically significant differences in the content and composition of individual phenolic acid in four forms between sun-drying and explosion puffing treatments were measured in the study,and their changes are complicated and uncertain.With explosion puffing,the four forms TPC of jujubes were significantly increased.Whereas the contents of sun-dried jujubes were marked decreased.The antioxidant activity of phenolic acids in the four forms in explosion-puffed jujubes was significantly higher than that of the fresh and sun-dried counterparts.(5)The result indicated that proanthocyanidins from jujube peel exhibited higher antioxidant activities than those from jujube pulp.The structures of oligomer and polymeric isolated from jujube peel and pulp were characterized by high performance liquid chromatography electrospray ionization mass spectrometry(HPLC-ESI-MS)analysis.According to initial speculation,the prodelphinidin dimmer was identified in jujube peel and pulp.Moreover,A-type trimers,(epi)catechin-3-O-glucoside were detected in jujube peel.While A-type and B-type oligomer were found in jujube pulp.After depolymerization with phloroglucinol,(epi)catechin and(epi)afzelechin were identified as the extension units,only epigallocatechin-3-O-gallate(EGCG)was present in terminal units in jujube peel.The(epi)catechin and EGCG were identified as the extension units,only(EGCG)was also detected in terminal units in jujube pulp.