Extraction,Functional Properties And Application Of Pectin From Stem And Leaf Of Beet

Red beet contains dietary fiber,protein,beet erythroxin,vitamins and other active substances,bright color,rich nutrition.Most of the roots are eaten and studied,while most of the stems and leaves are discarded except a small part of them are eaten as vegetables or used as green fodder,resulting in a relatively serious waste of resources.Pectin is a kind of heteropoly sugar widely used in food industry.In recent years,the extraction of pectin and other active ingredients from agricultural waste,which conforms to the concept of circular economy,has been paid more attention to by research.Therefore,it is of great significance to extract pectin from stem and leaf of red beet and explore its application in food industry.Gel gummy is soft in taste,delicious in taste and convenient to eat,which is deeply loved by consumers.The development of nutritive gel gummies with certain functional properties is one of the development trends in soft sweets field.Pectin can maintain intestinal health,reduce obesity,reduce blood sugar and other functional functions.Natural functional substances such as pectin can be added to soft sweets to improve the nutritional value of soft sweets,which has a good development prospect in the visible future.Two kinds of beet stem and leaf pectin,HA-PP and HAU-PP,were extracted by hot acid method and ultrasonic assisted hot acid method.After comparative analysis of the yield,structural composition and functional properties of the two,HAU-PP was selected to be added into the soft sweets,and it was used as a compound gel with gelatin,supplemented with a certain amount of sweetener and antioxidant,to study the best technological formula of beet stem and leaf pectin gel gummies.On this basis,the quality and characteristics of soft sweets were analyzed in order to improve the utilization rate of pectin of beet stem and leaf,and to provide theoretical basis for the multi-level development of gel gummies.The main research contents and experimental results of this paper are as follows:(1)Two extraction methods were used to obtain beet stem and leaf pectin: HA-PP and HAU-PP,and their yield was calculated.The optimal extraction process of HA-PP was determined by single factor experiment and response surface optimization experiment: p H 2,solid-liquid ratio 1:19 g/m L,extraction temperature 74℃,extraction time 126 min.Under these conditions,the yield was 21.07±0.08%.On the above basis,ultrasonic assisted hot acid method was used to extract HAU-PP.After adding certain ultrasonic process conditions,the yield of HAU-PP was 25.18±0.12%.(2)The structural composition of HA-PP and HAU-PP were analyzed.Their color,Fourier infrared spectroscopy(FTIR)and basic physicochemical properties were analyzed.Because of the different extraction methods,there were some differences in color.Both of them were confirmed to be pectin by identification and FTIR determination.Both FTIR and titration data showed that both were high methoxy-pectin.In addition,it was found that the ultrasonic process had a certain influence on the structural composition of pectin,which made the functional properties of the two will be different.(3)Functional properties of HA-PP and HAU-PP were analyzed.Compared with HA-PP,HAU-PP had good water retention,oil retention and expansion power,and had higher antioxidant capacity,cholesterol and nitrite adsorption capacity.These results indicated that HAU-PP can improve the texture of food and prolong the shelf life of food more easily,and had the potential to be used as an antioxidant and adsorbent of food,which is expected to be developed in food processing.(4)On the basis of the analysis of texture indexes,based on the sensory evaluation score of soft sweets,through single factor experiment and response surface optimization experiment,the optimal process formula of beet stem and leaf pectin gel gummies was determined as follows: total colloid amount 7.0%,pectin(HAU-PP)amount 0.7%,calcium chloride amount1.3%,citric acid amount 2.0%,sweetener ratio(xylitol amount : white granulated sugar amount)was 2.80:1,and the sweetener amount 19.0%.According to this process formula,the sensory score of soft sweets reached 90.97 points.(5)The beet stem and leaf pectin gel gummies obtained under the best technological formula have uniform texture,sweet and not greasy,and good chewability.The physical and chemical indexes and microbial indexes of soft sweets were determined as follows: per 100 grams of soft sweets contained 22.4 g water,4.9 g protein,0 g fat and 55.6 g carbohydrate,the total number of colonies was 76±0.49 CFU/g,and no coliform and pathogenic bacteria were detected.All indexes meet the requirements of GB 17399-2016 and other national standards.(6)Compared with commercially available soft sweets,the results showed that the beet stem and leaf pectin gel gummies developed in this paper are soft sweets that reduce calories.After adding HAU-PP,the deformation resistance of soft sweets was increased to a certain extent,which was 82.09±2.47%.The soft sweets can be stored for three months under the condition of not exceeding 25℃.