Research On Processing Technology Of Instant Black Jujube Powder And New Product Development Of Black Jujube Coffee

Jujube is a special medicinal and edible fruit with high nutritional value and rich functional components.By controlling temperature and humidity and other conditions processing red jujube black red jujube,black jujube for short.Instant black jujube powder is a new type of jujube product which is made from black jujube by extraction and drying.Due to its high sugar content,easy to absorb moisture and caking,the dissolution rate of jujube powder is reduced,which greatly limits its application in the field of instant food.Therefore,it is necessary to optimize the processing process and technology to improve the related properties of instant black jujube powder.Taking black jujube as raw material,this paper optimized the extraction process of black jujube juice,compared the influence of hot air drying and vacuum freezedrying on the dissolution characteristics and physicochemical indexes of instant black jujube powder,and determined the optimal drying process.A new black jujube coffee product was prepared by combining instant black jujube powder with coffee powder.The solubility and punchability were studied,and the sensory evaluation was carried out.The product meets the relevant national standards,which provides a theoretical basis for the development of instant black jujube series products.The main research results are as follows:(1)Study on extraction technology of black jujube juiceThe extraction rate,soluble solid content,total sugar,total acid,color and flavor of black jujube juice extracted by hot water and pectinase were determined.The results showed the extraction rate was 58±2% by hot water and 77±2% by pectinase.The soluble solid content of jujube extract obtained by hot water extraction method was 7.2±1%,and that by pectinase enzymolysis method was 8.6±1%.The content of Vc,total sugar and total acid of jujube liquid obtained by pectinase extraction was higher than that by hot water extraction.In conclusion,pectinase extraction significantly improved the utilization rate of raw materials and nutrient retention.(2)Hot air drying process of instant black jujube powderThe effects of hot air drying temperature,drying time,the amount of drying aid and anticoagulant on water content,dispersion time and solubility of instant black jujube powder were studied by single factor experiment.According to the response surface experiment,the optimum technological conditions were obtained by taking the solubility as the index.The results showed that the optimal hot air drying process of black jujube powder was as follows:hot air drying temperature 79.88 ℃,hot air drying time 10.40 h,drying agent addition amount8.00%,anti-coagulation agent addition amount 0.51%.Under this condition,the solubility of instant black jujube powder is 89.4%.(3)Study on vacuum freeze-drying technology of instant black jujube powderThe effects of vacuum freeze-drying temperature,drying time,the amount of drying aid and anti-coagulant on water content,dispersion time and solubility of instant black jujube powder were studied by single factor experiment,the optimal process conditions were obtained.The results showed the optimal vacuum freeze-drying process was as follows: vacuum freeze-drying temperature-45℃,drying time 36 h,maltodextrin content 18%,microcrystalline cellulose content 0.6%.Under this condition,the solubility of instant black jujube powder is 85.2%.(4)A comparative study on indexes of hot air drying instant black jujube powder and vacuum freeze drying instant black jujube powderThe indexes of hot air drying and vacuum freeze drying of instant black jujube powder were compared.The results showed that the pink degree of hot air drying jujube was 65,the protein content was 0.9674 g/100 g,the total sugar content was 0.45 mg/g,the vitamin C content was3.89 mg/g,and the flavonol content was 2.04 mg/g.The pink degree of vacuum freeze-dried jujube was 56,the protein content was 0.968 3g/100 g,the total sugar content was 0.58 mg/g,the vitamin C content was 4.30 mg/g and the flavonol content was 2.14 mg/g.The results showed that the vacuum freeze-dried instant black jujube powder had higher content of functional components and lighter color.Electronic nose test showed that both hot air dried instant black jujube powder and vacuum frozen instant black jujube powder had obvious principal components,and there were obvious differences between the two kinds of instant black jujube powder.By micro-solid phase extraction(spem-GC/MS)technology,42 kinds of effective aroma components of hot air drying instant black jujube powder and 43 kinds of effective aroma components of vacuum freeze-drying instant black jujube powder were detected,among which alkanes and acids were the main characteristic components.(5)Sensory evaluation and physicochemical properties of black jujube coffeeIn the experiment,the hot air dried instant black jujube powder and coffee powder were mixed in different proportions under better conditions,and the sensory evaluation was conducted.The black jujube coffee obtained by the 2:1 ratio of instant black jujube powder and coffee powder was the highest score.The physical and chemical properties of black jujube coffee were determined.The density was 0.393±0.02 g/m L,the dispersion time was 10±2 s,and the solubility was 88.2± 1%.