DE112018002352B4 - Process for conditioning the dehydration of Cordyceps militaris and for improving the quality thereof - Google Patents

Abstract

A method of conditioning the dehydration of Cordyceps militaris and improving the quality thereof, characterized in that the method comprises the following steps: (1) Sorting out and cleaning of the raw materials: fresh Cordyceps militaris of identical length and thickness, uniform color and without mechanical Damage is selected as raw materials, cleaning the selected raw materials to remove the impurities; (2) pretreatment using ultrasound in combination with concentrated fruit juice: soaking purified Cordyceps militaris in a concentrated fruit juice and performing an ultrasonic pretreatment; where the ultrasonic frequency 20-30 kHz, the power 400-2000W, the treatment time 5-10 min and the mass ratio of Cordyceps militaris to the concentrated fruit juice is 1: 2; (3) Freezing: cleaning of Cordyceps militaris after the ultrasonic pretreatment in step ( 2), then draining, and storing in an ultra-low temperature refrigerator for 5 h, until Cordyceps militaris are completely frozen; (4) vacuum pulse spray microwave freeze-drying: performing vacuum pulse spray microwave freeze-drying for the frozen Cordyceps militaris in step (3), drying, to the moisture content of the wet base is below 6% in order to obtain a dried product of Cordyceps militaris; the magnetron operating frequency is 2450 MHz and the microwave power is set to 2.2-2.6 W / g, and the spray duration is set to 0.1 s, and the spray interval is 10 minutes and the drying time is 3 to 3.5 hours ; (5) Rehydration for detecting browning: performing rehydration on the obtained dried product of Cordyceps militaris to detect whether a browning phenomenon occurs.

Description

TECHNICAL AREA

The present invention relates to a method of conditioning the dehydration of Cordyceps militaris and improving the quality of that which is mainly used for drying Cordyceps militaris.

STATE OF THE ART

Cordyceps militaris is also known as North Cordyceps militaris, belongs to the Hypocreales, Ergoidea. For thousands of years, Cordyceps militaris has been used as an edible mushroom in China in the field of diet treatment and traditional Chinese medicine ( Xiao Y, Xing G, Rui X, et al. Enhancement of the antioxidant capacity of chickpeas by solid state fermentation with Cordyceps militaris SN-18 [J]. Journal of Functional Foods, 2014, 10: 210-222. ). The edible value and medicinal value of Cordyceps militaris are very similar to those of Cordyceps sinensis, but the yield of Cordyceps sinensis is extremely low and the price is very high. Cordyceps militaris can be artificially cultivated, has a lower price and higher yield compared to Cordyceps sinensis, and can thus be used as a very good substitute for Cordyceps sinensis. Cordyceps militaris is nutrient-rich and contains a variety of active ingredients, such as adenine, cordycepin, cordycepin acid, cordyceps polysaccharide, ergosterol, amino acids, proteins, vitamins and the like. Cordyceps militaris has a good effect in the treatment of liver disease and relief of lung disease ( Zhu S, Pan J, Zhao B, et al. Comparisons on enhancing the immunity of fresh and dry Cordyceps militaris in vivo and in vitro [J]. Journal of ethnopharmacology, 2013, 149 (3): 713-719. In addition, Cordyceps militaris contains plenty of ergosterol and ergosterol, which can be converted into vitamin D under ultraviolet light. In recent years, Cordyceps militaris has been widely used for disease treatment as it has a variety of physiological functions such as anti-fatigue, anti-aging, anti-inflammation, and immune system balancing, etc. However, fresh Cordyceps militaris is not easy to store and is extremely perishable after harvest, which leads to a loss of nutrients and a deterioration in the quality of consumption. Appropriate preservation methods are therefore of great importance in extending the shelf life of Cordyceps militaris.

Inhibiting the growth and reproduction of microorganisms is an important means of extending the shelf life of foods. Water is one of the most important factors influencing the growth and reproduction of microorganisms in food. In the food industry, a drying process is commonly used to reduce the moisture content of the food in order to extend the shelf life of food. In the food industry, hot air drying is the most common drying method that is easy to use and control. However, hot air drying affects the quality of the product and leads to the loss of nutrients. Freeze-drying is known for its high-quality drying properties, but freeze-drying takes a long time and requires a vacuum pump and a water circuit, which results in high energy consumption for drying, which increases production costs. In order to counteract the shortcomings of freeze drying with a long period of time and high energy consumption, microwave drying is introduced to support the drying process, namely microwave freeze drying. Compared to traditional freeze drying, microwave freeze drying can reduce the drying time by 50% ( Jiang H, Zhang M, Mujumdar AS, et al. Comparison of drying characteristic and uniformity of banana cubes dried by pulse-spouted microwave vacuum drying, freeze drying and microwave freeze drying [J]. Journal of the Science of Food and Agriculture, 2014, 94 (9): 1827-1834. ). However, new problems have emerged. The uneven distribution of the microwave field in microwave freeze drying leads to a “peak discharge” effect during the drying process, which leads to melting of the ice crystal, causing the dried product to experience a phenomenon of shrinkage or overheating. To solve this problem, the laboratory invented a vacuum microwave spray auxiliary freeze dryer. The vacuum microwave spray auxiliary freeze-drying combines the advantages of microwave freeze-drying and conventional freeze-drying; the spray mode enables the materials to be dispersed at different points in the drying chamber during the drying process, which results in a uniform and efficient drying of high quality (Wang Y, Zhang M, Mujumdar AS, et al. Microwave-assisted pulse-spouted bed freeze-drying of stem lettuce slices-Effect on product quality [J]. Food and bioprocess technology, 2013, 6 (12): 3530-3543. ).

Since the vacuum microwave spray auxiliary freeze drying has a lower temperature in the whole drying process, the colors and nutrients in the dried materials can be preserved at the highest level, which keeps the substances and enzymes in Cordyceps militaris well preserved. This is a phenomenon with severe browning occurs in the rehydration process of the fruiting bodies of Cordyceps militaris.

Because of this, the present invention uses ultrasound in combination with concentrated fruit juice as a pretreatment for enzyme inactivation and deodorization, at the same time the cavitation of the ultrasound causes the surface adhesion of the water to be reduced, whereby the migration resistance is reduced and the outflow of the internal water content of Cordyceps militaris is promoted, which is beneficial for the subsequent freeze-drying process.

Yalu Cai et al. CN104784238 A discloses a steam blanching, microwave killout and vacuum freeze drying processing method for Berg Huang chrysanthemum, with the two techniques of steam blanching, microwave killout treats the process of polyphenol oxidase in Berg Huang chrysanthemum to prevent discoloration, then vacuum freeze drying is performed, to effectively shorten the drying time and improve the drying efficiency, while maintaining the chlorogenic acid and luteoline glycosides and other active ingredients in Chrysanthemum from Berg Huang. Using the ultrasound in combination with concentrated fruit juice, the present invention carries out a pretreatment of enzyme inactivation for Cordyceps militaris, then a vacuum microwave spray auxiliary freeze-drying is carried out, which significantly shortens the drying time and the energy consumption for the drying can be saved, while the quality maintained by Cordyceps militaris.

Qian Cai CN 105674687 A discloses a microwave vacuum freeze-drying process for dendrobium, after the fuming and evaporation of dendrobium with the steam, a pre-cooled process is carried out, then freezing at -32-36 ° C, which realizes microwave freeze-drying. With the process, the active ingredients of Dendrobium can be retained to the highest degree, with a high drying speed and a short drying time. The present invention uses a vacuum pulse spray mode to perform microwave freeze-drying for Cordyceps militaris, thereby the uniformity of microwave freeze-dried products can be improved, thereby improving the quality of the dried product while also improving production efficiency.

Min Zhang et al. CN 102987524 A discloses a pulse spray microwave freeze drying for the particulate processing of food and an efficient homogenized processing method, in which method a gas-solids separator is connected to an outlet opening of the vacuum drying tube in the microwave heating chamber and connected by a pipe to a water catcher. The apparatus can spray and rotate the materials under the microwave freeze drying conditions to achieve efficient and uniform drying. Compared to the present invention, this patent focuses mainly on the design of microwave freeze drying, while the explanations regarding the parameters of the quality of the material are relatively poor. The present invention uses ultrasound in combination with concentrated fruit juice to pretreat Cordyceps militaris, thereby a phenomenon of browning in the rehydration process can be prevented, and with the ultrasound pretreatment, the following drying time can be shortened and the drying quality can be improved.

Min Zhang et al. CN 101703196 A discloses a segmentation method for enhancing the uniformly puffed effect of particulate fruits and vegetables in microwave spray drying. The process performs blanching, enzyme inactivation, and color protection treatment for fruits and vegetables, after which a segmentation process of hot air drying and microwave spray drying is used so that the water content of fruits and vegetables is quickly evaporated, and the dried fruit and vegetable products have a porous Structure, which increases the puffed degree. The patent uses a traditional blanching method to perform enzyme inactivation on fruits and vegetables while emphasizing the puffed effect of the product. The present invention uses ultrasound in combination with concentrated fruit juice to effect enzyme inactivation and deodorization, focusing on inhibiting browning in the rehydration process of the product after microwave spray freeze drying and removing odors.

Difeng Ren et al. ( CN 102793216 A ) discloses a method for making spirulina powders using microwave vacuum freeze drying. The present invention uses fresh spirulina as raw material, after pre-freezing and microwave vacuum freeze-drying, the obtained spirulina powders have good flowability, and their coloring components are relatively well retained and higher in alginate protein content. In the present invention, fresh Cordyceps militaris is dried after an ultrasonic pretreatment; the raw materials are not powdery, but rod-shaped. In addition, a pulse spray mode is used in the microwave freeze drying process to ensure uniformity to realize the drying of the product, while the process cannot be used for the powdery raw materials.

Min Zhang et al. ( CN 106234564 A ) discloses a method for improving the dehydration and rehydration of Pogostemon auricularius with the assistance of low frequency ultrasound. The procedure uses ultrasound to pretreat Pogostemon auricularius, in the early stages pulse low frequency microwaves are used in conjunction with vacuum freeze drying, while in the later stages hot air drying is used. The product obtained has a full texture and a rapid rate of rehydration, and the product after rehydration has full and round grains and higher elasticity. The patent also uses ultrasound as a pretreatment measure, its main purpose being to reduce the drying time and the rehydration time of the dried product. In the present invention, the ultrasound is used in combination with concentrated fruit juice for pretreatment, in addition to shortening the drying time, the main purpose is more focused on the inactivation function for the enzymes such as the polyphenol oxidase in Cordyceps militaris, which prevents the occurrence of a browning phenomenon in the rehydration process.

Jie Wang et al. ( CN 105942412 A ) discloses a method for extracting ergothioneine from edible mushrooms using ultrasonic microwaves in combination with vacuum freeze-drying. Although this invention also uses the techniques of ultrasound, microwave and vacuum freeze-drying, the process is such that vacuum freeze-drying is performed for pleurotus first and then the extraction liquid is treated with ultrasound and microwaves. This invention focuses on extracting the active ingredients from Pleurotus using microwaves and ultrasound, rather than helping to promote the freeze-drying process. The present invention uses the ultrasound to pre-treat Cordyceps militaris, then a vacuum pulse spray is applied to aid in microwave freeze drying while not affecting the extraction of the active ingredients of the raw materials or nutrients.

Yujing Sun et al. ( CN 102578674 A ) discloses a method of preventing the freshly squeezed apple juice from browning in which the freshly squeezed juice is treated using ultrasound to achieve a purpose of preventing the browning of the apple juice. Lubin Zhang et al. (Lubin Zhang, Kanghua Song, Hui Gu et al., Research on the freshness-keeping effect of citric acid treatment for browning freshly cut pereira praises [J]. Journal of Tropical Corps, 2017, 38 (6): 1143-1148. ) researched the influence of citric acid treatment on the color protection effect of freshly cut Pereira praises and discovered that the browning of freshly cut Pereira praises can be significantly reduced by pretreating with the appropriate concentration of citric acid. The present invention uses ultrasound in combination with concentrated fruit juice to pretreat the fruit bodies of Cordyceps militaris to achieve the purpose of inhibiting polyphenol oxidase, thereby preventing a browning phenomenon from occurring in the rehydration process of the dried products.

A few examples for production by means of microwave freeze-drying are described above. Compared to the methods reported in these examples, the method of the present invention uses ultrasound in combination with concentrated fruit juice to perform a pretreatment for Cordyceps militaris, then the microwave freeze-drying process is assisted by the vacuum pulse spray, thereby improving the drying efficiency of Cordyceps militaris, which Drying time is shortened and the energy consumption required for drying is reduced, while the nutrients and sensory quality of Cordyceps militaris are maintained at the highest level to prevent the occurrence of a tanning phenomenon in the rehydration stage after drying.

CN 107 028 074 A relates to a storage method for Cordyceps militaris in which an extract of Cordyceps militaris is produced which is subjected to vacuum freeze-drying.

CN 102 145 020 A relates to a freeze-drying and freshness-keeping method for processing Cordyceps sinensis, which includes the freeze-drying of Cordyceps sinensis.

CONTENT OF THE PRESENT INVENTION

The present invention aims to provide a method for conditioning the dehydration of Cordyceps militaris and improving the quality thereof, wherein ultrasound is used in combination with concentrated fruit juice for dehydration pretreatment to improve the drying efficiency of the subsequent vacuum microwave spray freeze-drying and the To improve the quality of Cordyceps militaris dried products, giving Cordyceps militaris the flavor of a fruit juice while removing the smells of Cordyceps militaris, and avoiding the occurrence of a tanning phenomenon in the rehydration process.

• Ein Verfahren zum Konditionieren der Dehydration von Cordyceps militaris und zum Verbessern der Qualität von dessen, wobei frisches Cordyceps militaris als Rohstoffe verwendet wird, das nach Klassifizieren und Aussortieren gereinigt wird, um die Verunreinigungen zu entfernen, und wobei dann unter Verwendung von Ultraschall in Kombination mit konzentriertem Fruchtsaft eine Vorbehandlung für Cordyceps militaris durchgeführt wird, und wobei nach Abtropfen ein Gefrieren erfolgt, und wobei am Ende eine Unterdruckimpuls-Mikrowellengefriertrocknung durchgeführt wird. Für das gefriergetrocknete Produkt wird eine Rehydratisierung durchgeführt, um zu detektieren, ob eine Bräunung auftritt. Die konkreten Prozesse sind wie folgt:
  • (1) Aussortieren und Reinigen der Rohstoffe: frisches Cordyceps militaris mit identischer Länge und Dicke, gleichmäßiger Farbe und ohne mechanischem Schaden wird als Rohstoffe ausgewählt, Reinigen der ausgewählten Rohstoffe, um die an der Oberfläche anhaftenden Verunreinigungen zu entfernen;
  • (2) Vorbehandlung unter Verwendung von Ultraschall in Kombination mit konzentriertem Fruchtsaft: Tränken von gereinigtem Cordyceps militaris in einem konzentrierten Fruchtsaft und Durchführen einer Ultraschallvorbehandlung; wobei die Ultraschallfrequenz 20-30 kHz, die Leistung 400-2000W, die Behandlungszeit 5-10 min und das Massenverhältnis von Cordyceps militaris zu dem konzentrierten Fruchtsaft 1:2 beträgt;
  • (3) Einfrieren: Reinigen von Cordyceps militaris nach der Ultraschallvorbehandlung im Schritt (2), anschließendes Abtropfen, und Lagern in einem Ultratieftemperatur-Kühlschrank für 5 h, bis Cordyceps militaris vollständig eingefroren sind;
  • (4) Unterdruckimpulsspray-Mikrowellengefriertrocknung: Durchführen einer Unterdruckimpulsspray-Mikrowellengefriertrocknung für das eingefrorene Cordyceps militaris im Schritt (3), Trocknen, bis der Feuchtigkeitsgehalt der Nassbasis unter 6% liegt, um ein getrocknetes Produkt von Cordyceps militaris zu erhalten; wobei die Magnetron-Betriebsfrequenz 2450 MHz beträgt und die Mikrowellenleistung auf 2,2-2,6 W/g, und die Spraydauer auf 0,1 s eingestellt ist, und wobei das Sprayintervall 10 min und die Trocknungszeit 3 bis 3,5 h beträgt;
  • (5) Rehydratisieren zum Detektieren einer Bräunung: Durchführen einer Rehydratisierung für das erhaltene getrocknete Produkt von Cordyceps militaris, um zu detektieren, ob ein Bräunungsphänomen auftritt.

The present invention employs the following technical solution:

• A method of conditioning the dehydration of Cordyceps militaris and improving the quality thereof, using fresh Cordyceps militaris as raw materials, which is purified after classifying and sorting to remove the impurities and then using ultrasound in combination with concentrated fruit juice, a pretreatment for Cordyceps militaris is carried out, and freezing takes place after draining, and at the end a vacuum pulse microwave freeze-drying is carried out. The freeze-dried product is rehydrated to detect whether browning occurs. The specific processes are as follows:
  • (1) Sorting out and cleaning the raw materials: fresh Cordyceps militaris of identical length and thickness, uniform color and without mechanical damage is selected as raw materials, cleaning the selected raw materials to remove the impurities adhering to the surface;
  • (2) pretreatment using ultrasound in combination with concentrated fruit juice: soaking purified Cordyceps militaris in a concentrated fruit juice and performing an ultrasonic pretreatment; where the ultrasonic frequency is 20-30 kHz, the power 400-2000W, the treatment time 5-10 min and the mass ratio of Cordyceps militaris to the concentrated fruit juice is 1: 2;
  • (3) Freezing: cleaning Cordyceps militaris after the ultrasonic pretreatment in step (2), then draining, and storing in an ultra-low temperature refrigerator for 5 hours until Cordyceps militaris are completely frozen;
  • (4) vacuum pulse spray microwave freeze-drying: performing vacuum pulse spray microwave freeze-drying for the frozen Cordyceps militaris in the step (3), drying until the moisture content of the wet base is below 6% to obtain a dried product of Cordyceps militaris; wherein the magnetron operating frequency is 2450 MHz and the microwave power is set to 2.2-2.6 W / g, and the spray duration is set to 0.1 s, and the spray interval is 10 minutes and the drying time is 3 to 3.5 hours ;
  • (5) Rehydration for detecting browning: performing rehydration on the obtained dried product of Cordyceps militaris to detect whether browning phenomenon occurs.

Cordyceps militaris has a diameter of 2-5mm and a length of 5-9 cm.

In step (2), the ultrasound frequency is 20 KHz, the power is 800 W and the treatment time is 10 minutes.

In step (3), the temperature of the ultra-low temperature refrigerator is -40 ° C, the freezing rate is 1 ° C / min and the freezing time is 5 hours.

In step (4), the microwave power is 2.2 W / g.

In step (5), the water temperature during rehydration is 25 ° C.

In step (2), the concentrated fruit juice is the concentrated lemon juice, orange juice and strawberry juice.

• (1) Die vorliegende Erfindung verwendet eine Mikrowellengefriertrocknungstechnik; im Vergleich zu herkömmlicher Gefriertrocknung wird die benötigte Trocknungszeit erheblich verkürzt und die Trocknungseffizienz verbessert,
• (2) Die vorliegende Erfindung verwendet einen Unterdruckimpulsspray-Modus, wodurch das schwierige Problem mit den ungleichmäßig verteilten Mikrowellenfeldern gelöst wird, so dass im Trocknungsprozess die Materialien gleichmäßig an verschiedenen Stellen der Trocknungskammer verteilt werden können, um eine Gleichmäßigkeit der Trocknung zu realisieren;
• (3) Die Verwendung des Ultraschalls in Kombination mit konzentriertem Fruchtsaft kann die Aktivität der Polyphenoloxidase von Cordyceps militaris wirksam reduzieren, wodurch Cordyceps militaris das Aroma eines Fruchtsafts verliehen wird, während die Gerüche von Cordyceps militaris entfernt werden. Darüber hinaus kann mit dem Ultraschall der Migrationswiderstand des Feuchtigkeitsgehalts in den Materialien reduziert werden, wodurch die Trocknungszeit wirksam verkürzt wird. Darüber hinaus wird Cordyceps militaris nach der Rehydratisierung auch kein Bräunungsphänomen haben.

The present invention has the following advantages:

• (1) The present invention uses a microwave freeze drying technique; Compared to conventional freeze drying, the required drying time is significantly reduced and the drying efficiency is improved,
• (2) The present invention uses a negative pressure pulse spray mode, which solves the difficult problem of the unevenly distributed microwave fields, so that in the drying process, the materials can be evenly distributed at different locations in the drying chamber to realize drying uniformity;
• (3) The use of the ultrasound in combination with concentrated fruit juice can effectively reduce the activity of the polyphenol oxidase of Cordyceps militaris, thereby imparting the flavor of a fruit juice to Cordyceps militaris while removing the odors of Cordyceps militaris. In addition, the ultrasound can reduce the migration resistance of the moisture content in the materials, thereby effectively shortening the drying time. In addition, Cordyceps militaris will not have a tanning phenomenon after rehydration either.

DETAILED DESCRIPTION

Embodiment 1: Method for dehydrating and improving the quality of Cordyceps using ultrasound in combination with concentrated lemon juice

Selecting 300 g of fruit bodies of fresh Cordyceps militaris of uniform color and without mechanical damage, as well as 2-3 mm in diameter and 5-6 mm in length, performing cleaning to remove the impurities adhering to the surface. Taking 600 g of concentrated lemon juice (Guangzhou Jiahao Lebensmittel GmbH), soaking the fruiting bodies of Cordyceps militaris in the concentrated lemon juice and performing an ultrasound pretreatment. The ultrasonic frequency is 20 kHz, the power 800 W, the treatment time 10 minutes and the mass ratio of Cordyceps militaris to the concentrated lemon juice is 1: 2. Cleaning and draining of the treated Cordyceps militaris fruit bodies and storing in an ultra-low temperature refrigerator and freezing for 5 hours until those of Cordyceps militaris are completely frozen, after which a vacuum pulse spray microwave freeze-drying is carried out for the frozen materials. The microwave power is set to 660 W (2.2 W / g), the spray duration to 0.1 s and the spray interval to 10 minutes. The drying time is 3.4 hours and is reduced by 62% compared to conventional freeze drying. The dried Cordyceps militaris has no odor and has a lemon aroma. A rehydration treatment is carried out for the dried fruiting bodies of Cordyceps militaris, the water temperature being 25 ° C, and the Cordyceps militaris having no browning phenomenon after rehydration.

Embodiment 2: Method for dehydrating and improving the quality of Cordyceps using ultrasound in combination with concentrated orange juice

Selecting 300 g of fresh Cordyceps militaris fruit bodies of uniform color and without mechanical damage, as well as 2-3 mm in diameter and 5-6 mm in length, and performing cleaning and removal of impurities. Take 600 g of concentrated orange juice (Guangzhou Jiahao Lebensmittel GmbH), soak the fruiting bodies of Cordyceps militaris in the concentrated orange juice and perform an ultrasound pretreatment. The ultrasonic frequency is 20 kHz, the power 800 W, the treatment time 10 min and the solution mass ratio of Cordyceps militaris to the concentrated orange juice 1: 2. Cleaning and draining of the treated Cordyceps militaris fruit bodies and storage in an ultra-low temperature refrigerator and freezing for 5 hours until the Cordyceps militaris fruit bodies are completely frozen, after which a vacuum pulse spray microwave freeze-drying is carried out for the frozen materials. The microwave power is set to 660 W (2.2 W / g), the spray duration to 0.1 s and the spray interval to 10 minutes. The drying time is 3.5 hours, compared to the conventional freeze-drying for the fruit bodies of Cordyceps militaris of the same size, the required drying time is reduced by 64%. The dried Cordyceps militaris is odorless and has an aroma of organs. A rehydration treatment is carried out for the dried fruiting bodies of Cordyceps militaris, the water temperature being 25 ° C, and the Cordyceps militaris having no browning phenomenon after rehydration.

Embodiment 3: Method of dehydrating and improving the quality of Cordyceps using ultrasound in combination with concentrated strawberry juice

Selecting 300 g of fresh Cordyceps militaris fruit bodies of uniform color and without mechanical damage, as well as 2-3 mm in diameter and 5-6 mm in length, and performing cleaning and removal of impurities. Taking 600 g of concentrated strawberry juice (Guangzhou Jiahao Lebensmittel GmbH), soaking the fruiting bodies of Cordyceps militaris in the concentrated strawberry juice and performing an ultrasonic pretreatment. The ultrasonic frequency is 20 kHz, the power 800 W, the treatment time 10 min and the solution mass ratio of Cordyceps militaris to the concentrated orange juice 1: 2. Cleaning and draining of the treated Cordyceps militaris fruit bodies and storage in an ultra-low temperature refrigerator and freezing for 5 hours until the Cordyceps militaris fruit bodies are completely frozen, after which a vacuum pulse spray microwave freeze-drying is carried out for the frozen materials. The microwave power is set to 660 W (2.2 W / g), the spray duration to 0.1 s and the spray interval to 10 minutes. The drying time is 3.5 hours, compared to the conventional freeze-drying for the fruit bodies of Cordyceps militaris of the same size, the required drying time is reduced by 64%. The dried Cordyceps militaris is odorless and has an aroma of organs. A rehydration treatment is carried out for the dried fruiting bodies of Cordyceps militaris, the water temperature being 25 ° C, and the Cordyceps militaris having no browning phenomenon after rehydration.

Claims (10)

A method of conditioning the dehydration of Cordyceps militaris and improving the quality thereof, characterized in that the method comprises the following steps: (1) Sorting out and cleaning of the raw materials: fresh Cordyceps militaris of identical length and thickness, uniform color and without mechanical Damage is selected as raw materials, cleaning the selected raw materials to remove the impurities; (2) pretreatment using ultrasound in combination with concentrated fruit juice: soaking purified Cordyceps militaris in a concentrated fruit juice and performing an ultrasonic pretreatment; where the ultrasonic frequency is 20-30 kHz, the power 400-2000W, the treatment time 5-10 min and the mass ratio of Cordyceps militaris to the concentrated fruit juice is 1: 2; (3) Freezing: cleaning Cordyceps militaris after the ultrasonic pretreatment in step (2), then draining, and storing in an ultra-low temperature refrigerator for 5 hours until Cordyceps militaris are completely frozen; (4) vacuum pulse spray microwave freeze-drying: performing vacuum pulse spray microwave freeze-drying for the frozen Cordyceps militaris in the step (3), drying until the moisture content of the wet base is below 6% to obtain a dried product of Cordyceps militaris; wherein the magnetron operating frequency is 2450 MHz and the microwave power is set to 2.2-2.6 W / g, and the spray duration is set to 0.1 s, and the spray interval is 10 minutes and the drying time is 3 to 3.5 hours ; (5) Rehydration for detecting browning: performing rehydration on the obtained dried product of Cordyceps militaris to detect whether browning phenomenon occurs. Procedure according to Claim 1 , characterized in that Cordyceps militaris has a diameter of 2-5mm and a length of 5-9 cm. Method according to Claim 1 or 2 , characterized in that in step (2) the ultrasonic frequency is 20 KHz, the power is 800 W and the treatment time is 10 minutes. Process for conditioning the dehydration of Cordyceps militaris and for improving the quality thereof Claim 1 or 2 , characterized in that in step (3) the temperature of the ultra-low temperature refrigerator is -40 ° C, the freezing rate is 1 ° C / min and the freezing time is 5 hours. Process for conditioning the dehydration of Cordyceps militaris and for improving the quality thereof Claim 3 , characterized in that in step (3) the temperature of the ultra-low temperature refrigerator is -40 ° C, the freezing rate is 1 ° C / min and the freezing time is 5 hours. Process for conditioning the dehydration of Cordyceps militaris and for improving the quality thereof Claim 1 , 2 or 5 , characterized in that in step (5) the microwave power is 2.2 W / g. Process for conditioning the dehydration of Cordyceps militaris and for improving the quality thereof Claim 3 , characterized in that in step (4) the microwave power is 2.2 W / g. Process for conditioning the dehydration of Cordyceps militaris and for improving the quality thereof Claim 4 , characterized in that in step (4) the microwave power is 2.2 W / g. Process for conditioning the dehydration of Cordyceps militaris and for improving the quality thereof Claim 1 , 2 , 5 , 7th or 8th , characterized in that in step (5) the water temperature during rehydration is 25 ° C. Process for conditioning the dehydration of Cordyceps militaris and for improving the quality thereof Claim 6 , characterized in that in step (2) the concentrated fruit juice is the concentrated lemon juice, orange juice and strawberry juice.