Optimization Deep-Processing Technology And Products Quality Evaluation Of Peeled‘Hui’Jujube Fruit In Southern Xinjiang

The jujube is a genus of plant in the family Rhamnaceae,rich in nutrients,and is a traditional medicinal food,known as the king of fruits.Xinjiang’s jujube production ranks among the top in the country,with southern jujube production accounting for over 90%of the total.At present,Xinjiang jujube products are mainly roughly processed products,with backward production technology,which cannot make full use of the nutritional value of jujube.The scale of jujube processing enterprises for high value-added products is relatively small,resulting in a small number of varieties of refined jujube products.The skin of the jujube is mainly composed of crude fibre and has a hard texture.The skin of the jujube enters the downstream products with the production operations such as pulping,making the products always have the inherent black red colour of the skin,which seriously affects the taste,appearance and stability of the products.Therefore,in this study,the peeling process was optimized and evaluated based on the raw material of South China’s‘Hui’jujube,and the related jujube products such as jujube juice,jujube spray drying powder and jujube effervescent tablets were developed based on this process,and the quality and stability of the products were comprehensively evaluated.The main research contents and results of this paper are as follows:1.Optimization and evaluation of‘Hui’jujube peeling process:In this study,the alkaline peel ing process of‘Hui’jujube was investigated using‘Hui’dates as the test material,the scavenging ability of ABTS⁺free radicals and iron reducing power were used to evaluate the antioxidant acti vity,and the changes in metabolites were analysed using liquid chromatography-mass spectrometry（LC-MS/MS）.The results showed that the optimum process conditions were 3%lye concentration,3 min peeling time and 79℃peeling temperature.Under this process,the peeling rate of‘Hui’juj ube reached 99.98%,and the highest sensory score was 80.50±0.50.Compared with the pre-peelin g process,the ABTS⁺radical scavenging ability,iron reduction ability,total phenolic content and s oluble solids content of the dates showed a decreasing trend after peeling,and the difference was significant（P<0.05）.A total of 968 metabolites were identified by LC-MS/MS,and the KEGG enr ichment analysis revealed that flavonoids and nucleotides were the main functional components lost during the peeling process.2.Optimization and evaluation of the combined treatment of‘Hui’Jujube juice by ultrasound and complex enzyme:In order to obtain high yield‘Hui’jujube juice,this study used single-factor and response surface tests to design the combined ultrasound-composite enzyme treatment（EZM+US）process of‘Hui’jujube juice for optimisation,and compared it with heat treatment（Ck）,enzyme treatment（EZM）,ultrasound treatment（US）,ultrasound followed by enzyme treatment（US-EZM）and enzymatic digestion followed by ultrasound treatment（EZM-US）The overall quality of the juices was compared and stability evaluations were made.The results showed that the best EZM+US treatment conditions were:2:1 enzyme complex ratio,0.45%enzyme complex addition,1:7 liquid to material ratio（w/v）,70 W sonication power and 120 min sonication at 55°C.The juice yield was up to 78.96%and soluble solids content was 11.85%.The combination of ultrasonication and enzyme treatment had a synergistic effect on improving the juice quality of the jujube.Compared with the single treatment,the combination not only increased the juice yield and soluble solids content,but also retained more nutrients,enhanced antioxidant activity and stability,and improved the taste of the juice.3.Preparation and evaluation of physical and chemical properties of spray drying powder for‘Hui’jujube:In order to develop a stable date powder with high solubility,the juice obtained from was used as raw material,and the spray drying process of the juice was optimized by single-factor test.The results showed that the optimum conditions for the spray drying of‘Hui’jujube juice were 15%maltodextrin addition,170℃inlet air temperature,75 Hz inlet air flow rate and 30 rpm peristaltic pump speed.42.02±0.52%powder yield was achieved under these conditions;compared with the vacuum freeze-dried‘Hui’jujube powder,the spray drying powder of‘Hui’jujube had lower nutrient content,but the spray drying powder had higher solubility,lower moisture content and higher Compared with the vacuum freeze-dried powder,the spray drying powder had lower nutrient content,but the spray drying powder had higher solubility,lower moisture content and higher sensory score（P<0.05）,and the spray drying powder had more uniform particles and spherical microstructure,while the vacuum freeze-dried powder had uneven size and irregular shape,but the differences in the main chemical composition of the two dried powders were not significant（P>0.05）.The physicochemical properties of the ash date spray-dried powder remained basically stable when stored at 4℃and 25℃for 120 d.However,some physicochemical properties of the ash date spray-dried powder changed at 40℃with significant differences（P<0.05）.4.Preparation and evaluation of‘Hui’jujube Effervescent tablets:In order to solve the problems of long disintegration time,existence of precipitation after disintegration,lack of quality evaluation and stability study of‘Hui’jujube effervescent tablets.A functional effervescent tablet of‘Hui’jujube was developed by direct compression method using the above-mentioned spray drying powder of‘Hui’jujube as raw material,and the quality,antioxidant activity and stability of the effervescent tablet were evaluated,and the composition was characterized by IR.The results showed that the optimal formulation of the effervescent tablets was 55%of disintegrant addition,30%of ash date spray drying powder addition,2.5%of sweetener addition,PEG 6000 2%and 10.5%of filler（maltodextrin）;the quality met the relevant requirements of the 2020 edition of the Chinese Pharmacopoeia;the IC₅₀of DPPH free radicals of ash date effervescent tablets was 2.21 mg/m L and the IC₅₀of ABTS⁺The IC₅₀of free radicals was 3.72 mg/m L;the stability of ash jujube effervescent tablets was good under high temperature conditions,and the influence of high humidity conditions on the effervescent tablets was greater.