Study On Quality Changes Of Jujube Juice During Storge

Red jujube juice has the same nutritional value as red jujube,not only containing various nutrients such as sucrose,glucose,fructose,organic acids,amino acids,etc.,but also containing GABA(γ-Aminobutyric acid,c GMP(cyclic guanosine monophosphate),polysaccharides,c AMP(cyclic adenosine monophosphate),saponins,alkaloids,flavonoids,and triterpenoids,among other bioactive components.During the storage process,storage temperature and time can affect the sensory and physicochemical quality changes of jujube juice.However,there are currently few research reports on the storage of jujube juice.In order to grasp the changes in the quality of jujube juice during storage,this article conducted a study on the changes in sensory,physicochemical,and volatile components of jujube juice during storage.The main research results are as follows:1.Changes in physicochemical quality and sensory properties of jujube juice during storageDuring the storage process of jujube juice,as the storage time prolongs and the storage temperature increases,the sensory evaluation,p H,transmittance,sucrose,antioxidant activity,and polyphenols of jujube juice decrease.However,soluble solids,browning degree,HMF,total acids,total flavonoids,reducing sugars,fructose,glucose,and△E values continue to increase.The changes in total sugar and polysaccharides were not significant(p>0.05).After a storage time of 150 days,the HMF content showed no significant change at 4℃(p>0.05),but increased to 0.71 and 4.40μg/m L at 27 and 37℃,respectively;The retention rates of c AMP content at 4,27,and 37℃were 93.47%,92.51%,and 89.15%,respectively.The retention rates of c GMP content at 4,27,and 37℃were 89.44%,70.99%,and 64.69%,respectively.There was no significant change in p-hydroxybenzoic acid(p>0.05).Catechin,proanthocyanidins,catechin,epicatechin,rutin and phlorizin decreased to 89.55%,93.40%,94.57%,95.88%,96.29%and 97.87%respectively at 4,27 and 37℃;61.67%,60.43%,81.99%,95.73%,82.90%,82.32%;57.84%,51.34%,81.90%,95.07%,75%,69.47%.The retention rate of total phenol content is above 90%at temperatures of4,27,and 37℃.Overall,the higher the temperature and the longer the time,the faster the decrease in polyphenol content.The retention rates of DPPH under storage conditions of 4,27,and 37℃were 55.43%,55.43%,and 34.78%,respectively.The retention rates of ABTS~+under storage conditions of 4,27,and37℃were 94.49%,91.93%,and 78.10%,respectively.The research results showed that polyphenols and antioxidant activity decreased faster with increasing storage time and temperature.The jujube juice under different storage conditions was sampled regularly,and its samples were tested for microbiology.No bacterial colony and Escherichia coli were detected in all samples,which was commercially sterile.2.Changes in aroma and substance of jujube juice.2.Changes in volatile substances during storage of jujube juiceA total of 40 volatile components were identified from jujube juice,including alcohols(3 types),phenols(4 types),aldehydes(2 types),ketones(7 types),acids(12 types),esters(9 types),and others(3types).Its main volatile substances are acids and esters.When jujube juice is stored at 4℃,the highest content is Methyl benzoate,ethyl lauric acid,dibutyl phthalate,lauric acid,heptanoic acid,octanoic acid,n-hexanoic acid,2,5-di-tert-butylphenol;Under 4℃storage conditions,the esters of jujube juice decreased by 43.65%,the acids increased by 63%,and the phenols and aldehydes remained relatively stable.Under27℃storage conditions,the jujube juice contains more dibutyl phthalate,1,2-ethylene glycol monoacetate,ethyl lauric acid,2,5-di-tert-butylphenol,and more n-hexanoic acid,n-decanoic acid,and(S)-4-isopropyl-2-azolidinone;Under 27℃storage conditions,during the later stage of ketone storage,ketones such as 2-heptanone and acetophenone appeared in jujube juice.Esters decreased by 71.12%,acids increased by108.76%,aldehydes increased by 18.46%,and phenols increased by 122.43%.The jujube juice stored at37℃has the highest content of n-hexanoic acid,heptanoic acid,octanoic acid,isooctanoic acid,nonanoic acid,and n-decanoic acid;Under 37℃storage conditions,jujube juice showed a reduction of 88.68%in esters,an increase of 182.02%in acids,124.28%in phenols,and a decrease of 0.12%in ketonesμg/m L to9.24μg/m L,an increase of 295.38%in aldehydes.