Extraction Of Hawthorn Pectin And Preparation And Drying Of Sugar-reducing Hawthorn Stick

Hawthorn stick is a traditional Chinese snack,not only palatability strong,but also have appetizer spleen,treatment of dyspepsia and other effects,favored by consumers.The rich pectin in hawthorn is the key component of making hawthorn stick.Traditional hawthorn stick production needs to add a large amount of sucrose to form gel.In addition,the gel high sugar system has a strong binding force with water,which is not easy to remove when drying,so that the drying time of hawthorn stick is long.In view of the problems of high sugar content and long drying time of traditional hawthorn stick,this topic takes hawthorn fruit as raw material to prepare hawthorn pectin,analyzed the effects of different drying methods of hawthorn on the properties of pectin gel,discussed the pre-dehydration-promoted coagulation effect of pectin simulation system,optimized the formula and process of pre-dehydration-promoted coagulation of sugar-reduced hawthorn stick,compared and analyzed the drying characteristics and quality changes of sugar-reduced hawthorn stick with different drying methods.The results are expected to provide guidance for efficient and high quality production and processing of sugar-reduced hawthorn stick.The main research contents and results are as follows:Firstly,the hawthorn pectin was extracted and analyzed,the basic information of hawthorn pectin was obtained,and the effects of different drying pretreatment methods on the properties of hawthorn pectin were compared.Hawthorn dry powder was prepared by different drying methods and pectin was extracted from hawthorn dry powder.The air-dried hawthorn fruit pectin(ADHFP),microwave-vacuum-dried hawthorn fruit pectin(MVDHFP)and conventional freeze-dried hawthorn fruit pectin(CFDHFP)were obtained.The effects of different drying pretreatment methods on apparent viscosity,monosaccharide composition,molecular weight,chemical structure,Degree of methoxylation,gel properties and microstructure of pectin were compared.Hawthorn pectin was composed of glucose,rhamnose,galactose,mannose and galacturonic acid(Gal A),with high molecular weight and DM.The main force of the gel is hydrogen bond and hydrophobic interaction.CFDHFP has the highest molecular weight and DM,resulting in a gel with the highest hardness,viscosity and chewiness,which binds more tightly to water.ADHFP had the highest Gal A content,the least number of side chains and the weakest gel.Fourier transform infrared spectroscopy showed that there was no significant difference in the structure of the three pectin.Compared with commercial citrus pectin,hawthorn pectin has higher food application potential.Hawthorn is a potential source of pectin.Secondly,the pre-dehydration-promoted coagulation research were carried out of pectin simulation system and sugar-reduced hawthorn stick,and analyzed the quality characteristics of sugar-reduced hawthorn stick.The feasibility of dehydration and coagulation promotion was verified by hawthorn pectin,and then applied to the production of Hawthorn strip.The sugar content of hawthorn stick can be reduced from 85%to 60%,and the drying time can be shortened by 8 h.The optimal temperature of pre-dehydration and drying is 50℃.The anti-oxidation ability of sugar-reduced hawthorn stick produced by pre-dehydration promotes coagulation was enhanced.The L*value of finished product decreased,a*increased,b*value decreased;The contents of total phenols,flavonoids,ascorbic acid and anthocyanins were 25.58mg/100g,21.55 mg/100g,51.55 mg/100g and 11.97 ug/g,respectively.Compared with traditional hawthorn stick,total phenols,flavonoids,ascorbic acid and anthocyanins were increased by 6.1 mg/100g,4.79 mg/100g,13.44 mg/100g and 2.84 ug/g,respectively,and the total sugar content was decreased by 4.51%.Sugar-reduced hawthorn stick had stronger hardness,chewiness,adhesion and cohesion,and had stronger flavor.Finally,aiming at the problem of long drying cycle in hawthorn stick process,carried out research on efficient drying technology and analyzed the effects of hot air drying(AD),mid-infrared drying(MIRD),radio frequency drying(RFD)and vacuum drying(VD)on the drying characteristics and quality of hawthorn stick.The results show that,among the four drying modes of MIRD,RFD,AD and VD,the drying time of RFD was the shortest(32 h),followed by MIRD(40 h),VD(52 h)and AD(64 h).In the drying process,the temperature of RFD material was uneven,while the surface of MIRD material was heated evenly.VD dried hawthorn stick had the highest antioxidant capacity and the highest retention rate of flavonoids and polyphenols.The overall difference of volatile components of samples prepared by different drying methods was relatively small,and PCA could not distinguish them well.MIRD hawthorn stick had the highest score in sensory evaluation.Considering the drying characteristics and quality attributes of dried products,MIRD was selected to optimize the drying process.And the optimal drying conditions were determined as follows:drying temperature 50℃,wind speed 1.0 m/s,radiation distance 14 cm and loading coefficient 7.4kg/m~2.