| The traditional processing methods of traditional Chinese medicinal materials include drying,baking,fumigating sulphur(or stir frying,cooking),and so on.These traditional raw material processing methods are not only poor in appearance phase:wrinkle deformation,oxidation and fumigation cause the color of black and black,and the processing process is not very good.All kinds of active ingredients in the original medicinal materials are preserved,so that the content of effective components is greatly reduced.On the other hand,due to the poor conditions of the traditional processing methods of origin or not in conformity with the national standard,the heavy metals and other harmful substances are seriously exceeding the standard.With the rapid development of vacuum freeze-drying technology in the processing of Chinese herbal pieces,the advantage of freeze-dried Chinese herbal pieces in the market of Chinese herbal medicine is increasing.However,because many processing plants are not mature,and the process of vacuum freeze drying is time consuming and energy consuming,the quality of the products after processing is often ignored in order to save energy,which leads to the uneven quality of the frozen dried Chinese medicine beverage market and the quality can not be guaranteed.In this study,the characteristics of the vacuum freeze-drying and the content of the active ingredients and the conditions of the freeze-drying process and the advantages of the freeze-dried slices of three kinds of Chinese herbal medicinal were studied in this study.The following conclusions are obtained:1.The vacuum freeze drying technology of three kinds of Yunnan medicinal herbs:Gastrodia elata,Bletilla striata and Panax notoginseng was studied.The law of material properties and vacuum freeze drying process parameters was summed up in combination with the characteristics of the material.It was found that the conditions for the vacuum freeze drying of Gastrodia elata were 45pa?55??5mm,and the content of active components were as follows:the content of Gastrodin was0.480%±0.029%,the content of Gastrodia polysaccharide was 22.97%±0.38%,the content of 4-hydroxy-benzyl alcohol was 0.288%±0.009%,the content of Alcohol-soluble extract was 32.38%±0.20%,the power consumption was 18.6KW*h,the comprehensive score was the highest;the conditions for the vacuum freeze drying of Bletilla striata were 55pa?58??5mm,the contents of the indexes of each investigation were:the content of Bletilla striata polysaccharide was 11.73%±0.35%,the content of Bletilla bibenzyl compound was 2.08%±0.08%,the content of Alcohol-soluble extract was 15.35%±1.02%,the power consumption was 19.0KW*h,the comprehensive score was the highest;the conditions for the vacuum freeze drying of Panax notoginseng were 75pa?38??5mm,the contents of the indexes of each investigation were:the content of five main saponins from Panax notoginseng was7.640%±0.476%,the conteng of Dencichine was 1.790%±0.008%,the content of Alcohol-soluble extract was 36.94%±0.15%,the power consumption was 20.9KW*h,the comprehensive score was the highest.The conditions for the vacuum freeze drying of three kinds of Chinese herbal medicinal and the physicochemical properties of mainly active ingredients:Gastrodin,Bletilla striata polysaccharide and five main saponins from Panax notoginseng are closely related.2.Because of the long time and energy consumption of the vacuum freeze drying process,in order to maximize the efficiency of the freeze drying of Chinese herbal medicine and reduce the energy consumption,the drying rate,productivity and area shrinkage rate of the three drying characteristic indexs of vacuum freeze-drying were studied.It is found that the three drying characteristic indexs of Bletilla striata are far less than Gastrodia elata and Panax notoginseng,and the value of three drying characteristic indexs are similar in Gastrodia elata and Panax notoginseng.According to the analysis of the material properties and the content of basic nutrients,it was found that the hardness of the section of Gastrodia elata was 17.08±0.19kg/cm~2,the hardness of the section of Bletilla striata was 21.27±0.74kg/cm~2,and the hardness of the section of Panax notoginseng was 15.68±0.25kg/cm~2.The order of hardness of the section:Bletilla striata>Gastrodia elata>Panax notoginseng;The content of crude fiber for Gastrodia elata,Bletilla striat and Panax notoginseng were 2.73%±0.05%,4.49%±0.33%and 3.27%±0.10%.The content of crude fiber for Bletilla striata was higher than Gastrodia elata and Panax notoginseng,and the content of crude fiber for Gastrodia elata and Panax notoginseng were similar.Because of the different character of the three kinds of Chinese herbal medicine,the drying rate,productivity and area shrinkage of the vacuum-freeze drying process are different.3.In order to highlight the advantages of vacuum freeze drying technology than the traditional Chinese medicine processing technology,this study compared the quality indexes(infrared fingerprint,morphology,FE-SEM characterization and chromaticity analysis)of the three kinds of freeze-dried slices:Gastrodia elata,Bletilla striata and Panax notoginseng with other conventional drying methods.The results showed that there were no obvious difference in the infrared fingerprint of the three kinds of dry materials,just because of the difference of sampling volume,there is a certain difference in peak intensity,and it is similar to the infrared fingerprint of fresh materials.It showed that the chemical composition of three kinds of Chinese herbal pieces did not change after drying in different drying ways.The internal structure of the material slices was observed by field emission scanning electron microscopy found that the inner cell or tissue structure of the fresh sample is characterized by a certain regularity and a number of inhomogeneous cracks or tiny pores in the interior,and the macroscopic performance is that the surface of the slice is smooth and has the proper hardness and brittleness.The freeze-dried samples undergo a slow drying process under the conditions of vacuum and low temperature,so the inner cell or tissue structure remains relatively complete,and the minimum degree of shrinkage deformation appears,which is less different from the fresh sample.Due to the slow heating of the internal water in the ice crystal state,the inner water is sublimated to the gas loss,so there are many porous honeycomb structures in the interior,and the macroscopic performance is the minimum hardness and brittleness,and there is no oxidation discoloration.The sample of room temperature drying(RTD)has undergone a long drying process under natural conditions,so a small degree of cell collapse and tissue damage are produced within the sample,and the macro performance is moderate hardness and brittleness,and a certain degree of oxidation discoloration occurs.Because of the rapid drying in the non vacuum and high temperature conditions,the internal moisture of the slice was rapidly lost,so the internal collapse and tissue contraction deformation appeared in the hot air drying(HD)sample,and the macro performance was the highest hardness,and the section appeared severe contraction deformation and oxidation discoloration.In conclusion,the freeze-dried sample is the highest in the appearance quality of Chinese herbal pieces. |
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