A method and device for combined fermentation of citrus by lactobacillus and aspergillus

Abstract

The present invention belongs to the field of biological fermentation technology, and specifically relates to a method and device for co-fermenting citrus with lactobacillus and aspergillus. The present invention uses aspergillus to ferment citrus peels, and the hydrolase produced by aspergillus fermentation can fully decompose pectin and fiber in citrus peels, and the decomposition and utilization rate of pectin and fiber in citrus peels reaches more than 60%; and the present invention uses lactobacillus to synchronously ferment citrus pulp, and the liquid fermentation product produced by the fermentation of citrus peels is mixed with citrus pulp. The synchronous fermentation of citrus peels and citrus pulp avoids mutual inhibition between aspergillus and lactobacillus, ensures the fermentation efficiency of the two, realizes the mixing of metabolites, can enhance the fermentation effect of citrus pulp, and improve the content of flavonoids and other polyphenols in the fermentation product of citrus pulp. Compared with the lactobacillus fermentation of citrus pulp alone, the flavonoids are increased by more than 55%; the flavor of the fermented product can also be improved, and the degradation rate of bitter substance naringin reaches more than 45%.

Description

Technical Field

[0001] The invention belongs to the technical field of biological fermentation, and particularly relates to a method and a device for jointly fermenting citrus with lactobacillus and aspergillus. Background Art

[0002] Citrus, as one of the most widely grown fruits in the world, is not only rich in nutritional value, but also loved by consumers for its unique flavor and aroma. However, traditional citrus processing methods, such as juicing and canning, are often accompanied by the loss of nutrients and a decrease in product taste. In addition, these methods may also generate a large amount of waste and environmental pollution during the production process. Therefore, it is particularly important to improve citrus processing technology and achieve full utilization and nutrient retention of citrus.

[0003] Microbial fermentation technology is increasingly used in the field of food processing, especially in the processing of fruit and vegetable products. At present, in citrus processing, lactobacillus is usually used to ferment the pulp and juice to obtain fermented products. However, due to the lack of relevant enzymes for decomposing pectin, fiber and protein, lactobacillus cannot fully utilize the nutrients in citrus peel. In addition, the long fermentation cycle of lactobacillus will face the problem of nutrient deficiency in the citrus matrix fermentation environment, resulting in slow growth and affecting the fermentation process; in addition, it is difficult to effectively reduce the obvious bitterness in citrus products by lactobacillus fermentation. Although Aspergillus fermentation can fully degrade macromolecular components such as pectin in the peel and decompose bitter substances in the juice, it cannot be carried out simultaneously and efficiently with lactobacillus fermentation due to differences in the optimal fermentation conditions. At present, Lactobacillus and Aspergillus have their own advantages and disadvantages in citrus matrix fermentation, and cannot be simply mixed and fermented synchronously, so this technology aims to solve the above defects and give full play to the advantages. Summary of the invention

[0004] The purpose of the present invention is to make up for the deficiencies of the prior art, shorten the citrus fermentation cycle, improve the decomposition and utilization rate of citrus peel cellulose and pectin, improve the flavor of citrus pulp fermentation products, increase the flavonoid content of the fermentation products and the degradation rate of the bitter substance naringin, and improve the fermentation efficiency.

[0005] To achieve the above object, the present invention provides a citrus fermentation method, comprising the following steps:

[0006] Mixing crushed citrus peels, water and Aspergillus niger to obtain a first fermentation material;

[0007] Mixing citrus juice obtained by squeezing the pulp with lactobacillus to obtain a second fermentation material;

[0008] Performing a first fermentation on the first fermentation material; the temperature of the first fermentation is 28-32° C.;

[0009] Performing a second fermentation on the second fermentation material; the temperature of the second fermentation is 34-37° C.;

[0010] The first fermentation and the second fermentation are carried out simultaneously. During the first fermentation and the second fermentation, the fermentation product of the first fermentation material is separated into solid and liquid, and the generated liquid material is mixed and fermented with the fermentation product of the second fermentation material; the temperature of the mixed fermentation is 34-35°C.

[0011] Preferably, the time for the solid-liquid separation is 1 / 3 to 1 / 2 and 2 / 3 to 3 / 4 of the fermentation cycle of the first fermentation.

[0012] Preferably, the fermentation cycles of the first fermentation and the second fermentation are 6 to 8 days respectively.

[0013] Preferably, the ratio of the total mass of the crushed citrus peel and water to the number of live bacteria of Aspergillus is 1-1.2 kg: 1×10 10 ~1×10 11 CFU;

[0014] The ratio of the mass of the citrus juice to the number of viable lactobacilli is 1-1.5 g: 1×10 7 ~1×10 9 CFU.

[0015] Preferably, the Aspergillus includes Aspergillus niger and / or Aspergillus oryzae; and the Lactobacillus includes Lactobacillus acidophilus.

[0016] Preferably, the first fermentation and the second fermentation are carried out in a fermentation device; the fermentation device comprises a fermentation tank, a stirring mechanism and a heating mechanism 7; the heating mechanism 7 is arranged on the inner side wall of the fermentation tank;

[0017] A reversible hole-shaped mechanism 6 is horizontally arranged inside the fermentation tank, and the reversible hole-shaped mechanism 6 divides the fermentation tank into an upper fermentation tank and a lower fermentation tank; the upper fermentation tank performs the first fermentation; and the lower fermentation tank performs the second fermentation;

[0018] A filtering mechanism is laid on the side of the reversible hole-shaped mechanism 6 close to the upper fermentation tank; a pull-out mechanism 13 is provided on the side of the filtering mechanism close to the upper fermentation tank, horizontally penetrating the fermentation tank, and when the pull-out mechanism 13 is opened, the liquid material produced by the upper fermentation tank passes through the filtering mechanism and the reversible hole-shaped mechanism 6 and enters the lower fermentation tank;

[0019] The upper fermentation tank is provided with an upper feed inlet 1, a pressure detection mechanism 5 and a temperature detection mechanism 10; the lower fermentation tank is provided with a lower feed inlet 11, a slag discharge port 8, a liquid discharge port 9 and a temperature detection mechanism 10;

[0020] The stirring mechanism vertically penetrates the upper fermentation tank, and the bottom of the stirring mechanism is suspended on the lower surface of the lower fermentation tank.

[0021] Preferably, the stirring mechanism comprises a power mechanism 2 and a propeller 4; the power mechanism 2 and the propeller 4 are connected via a connecting shaft 3;

[0022] The propeller 4 includes an upper propeller and a lower propeller; the upper propeller is located at the bottom of the upper fermentation tank; the lower propeller is located in the middle of the lower fermentation tank;

[0023] The withdrawable mechanism 13 is located between the upper propeller and the filtering mechanism.

[0024] Preferably, the aperture of the reversible hole-shaped mechanism 6 is 2 mm, the porosity is 70% to 75%, and the aperture is evenly distributed on the reversible hole-shaped mechanism 6;

[0025] The filtering mechanism comprises a filter screen, and the porosity of the filter screen is 0.4-0.6 μm.

[0026] The present invention also provides a fermentation device, comprising a fermentation tank, a stirring mechanism and a heating mechanism 7; the heating mechanism 7 is arranged on the inner wall of the fermentation tank;

[0027] A reversible hole-shaped mechanism 6 is horizontally arranged inside the fermentation tank, and the reversible hole-shaped mechanism 6 divides the fermentation tank into an upper fermentation tank and a lower fermentation tank;

[0028] A filtering mechanism is laid on the side of the reversible hole-shaped mechanism 6 close to the upper fermentation tank; a pull-out mechanism 13 is provided on the side of the filtering mechanism close to the upper fermentation tank, horizontally penetrating the fermentation tank, and when the pull-out mechanism 13 is opened, the liquid material produced by the upper fermentation tank passes through the filtering mechanism and the reversible hole-shaped mechanism 6 and enters the lower fermentation tank;

[0029] The upper fermentation tank is provided with an upper feed inlet 1, a pressure detection mechanism 5 and a temperature detection mechanism 10; the lower fermentation tank is provided with a lower feed inlet 11, a slag discharge port 8, a liquid discharge port 9 and a temperature detection mechanism 10;

[0030] The stirring mechanism vertically penetrates the upper fermentation tank, and the bottom of the stirring mechanism is suspended on the lower surface of the lower fermentation tank.

[0031] Preferably, the stirring mechanism comprises a power mechanism 2 and a propeller 4; the power mechanism 2 and the propeller 4 are connected via a connecting shaft 3;

[0032] The propeller 4 includes an upper propeller and a lower propeller; the upper propeller is located at the bottom of the upper fermentation tank; the lower propeller is located in the middle of the lower fermentation tank;

[0033] The drawable mechanism 13 is located between the upper propeller and the filtering mechanism;

[0034] The aperture of the reversible hole-shaped structure 6 is 2 mm, the porosity is 70% to 75%, and the aperture is evenly distributed on the reversible hole-shaped structure (6);

[0035] The filtering mechanism comprises a filter screen, and the porosity of the filter screen is 0.4-0.6 μm.

[0036] Beneficial effects:

[0037] The invention provides a citrus fermentation method, comprising the following steps: mixing crushed citrus peels, water and Aspergillus to obtain a first fermentation material; mixing citrus juice and lactobacillus to obtain a second fermentation material; performing a first fermentation on the first fermentation material; the temperature of the first fermentation material is 28-32°C; performing a second fermentation on the second fermentation material; the temperature of the second fermentation material is 34-37°C; the first fermentation and the second fermentation are performed simultaneously, and during the first fermentation and the second fermentation, solid-liquid separation is performed on a fermentation product of the first fermentation material, and the generated liquid material is mixed and fermented with the fermentation product of the second fermentation material; the temperature of the mixed fermentation is 34-35°C. The present invention utilizes Aspergillus to ferment citrus peels. The hydrolytic enzymes such as pectinase, protease, cellulase, etc. produced by Aspergillus fermentation can fully decompose macromolecules such as pectin and fiber in the citrus peels, and the decomposition and utilization rates of pectin and fiber in the citrus peels are respectively more than 60%; the citrus peels and citrus pulps of the present invention are fermented synchronously, avoiding the mutual inhibition of Aspergillus and Lactobacillus, and ensuring the fermentation efficiency of both; and the present invention mixes the liquid fermentation product produced by the fermentation of citrus peels with the citrus pulp to achieve the mixing of metabolites, which can enhance the fermentation effect of the citrus pulp and increase the content of flavonoids and other polyphenols in the fermentation product of the citrus pulp. Compared with the lactobacillus fermentation of the citrus pulp alone, the flavonoids are increased by more than 55%; the flavor of the fermented product can also be improved, and the degradation rate of the bitter substance naringin by the naringinase produced by Aspergillus fermentation is as high as 48%. The fermentation method provided by the present invention has a short fermentation cycle and high fermentation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required to be used in the embodiments are briefly introduced below.

[0039] Figure 1 It is a schematic diagram of the fermentation device of Example 1; wherein, 1-upper layer feed inlet, 2-motor, 3-connecting shaft, 4-propeller, 5-pressure gauge, 6-reversible porous partition, 7-heating resistance wire, 8-slag discharge port, 9-liquid discharge pump, 10-temperature sensor, 11-lower layer feed inlet, 12-pressure pump, 13-pullable baffle. DETAILED DESCRIPTION

[0040] The present invention provides a citrus fermentation method, comprising the following steps:

[0041] Mixing crushed citrus peels, water and Aspergillus niger to obtain a first fermentation material;

[0042] Mixing citrus juice obtained by squeezing the pulp with lactobacillus to obtain a second fermentation material;

[0043] The first fermentation material is subjected to a first fermentation; the temperature of the first fermentation material is 28-32° C.;

[0044] performing a second fermentation on the second fermentation material; the temperature of the second fermentation material is 34-37° C.;

[0045] The first fermentation and the second fermentation are carried out simultaneously. During the first fermentation and the second fermentation, the fermentation product of the first fermentation material is separated into solid and liquid, and the generated liquid material is mixed and fermented with the fermentation product of the second fermentation material; the temperature of the mixed fermentation is 34-35°C.

[0046] As an embodiment, the present invention performs a crushing process on citrus peel to obtain crushed citrus peel. As an embodiment, the crushing process of the present invention can use a roller press. As an embodiment, the degree of the crushing process is to make the peel particle size uniform, with a diameter of about 5 mm, and not in a pulpy state. The present invention performs a crushing process on citrus peel, aiming to fully contact and ferment after inoculation with Aspergillus, and to facilitate solid-liquid separation after fermentation.

[0047] As an embodiment, after obtaining the crushed citrus peel, the present invention mixes the crushed citrus peel with water to obtain a citrus peel fermentation matrix. As an embodiment, the mass ratio of the crushed citrus peel and water in the present invention is (1-1.5): (1-3); as another embodiment, the mass ratio of the crushed citrus peel and water in the present invention is 1:2.

[0048] As an embodiment, after obtaining the citrus peel fermentation substrate, the present invention mixes the citrus peel fermentation substrate and Aspergillus to obtain a first fermentation material. As an embodiment, the ratio of the mass of the citrus peel fermentation substrate to the number of live bacteria of Aspergillus is 1-1.2 kg: 1×10 10 ~1×10 11 CFU; As another embodiment, the ratio of the mass of the citrus peel fermentation substrate of the present invention to the number of viable Aspergillus is 1kg:1×10 10 CFU. As an embodiment, the Aspergillus of the present invention includes Aspergillus niger and / or Aspergillus oryzae; as another embodiment, the Aspergillus of the present invention is Aspergillus niger or Aspergillus oryzae. The present invention has no strict requirements on the sources of the Aspergillus niger and Aspergillus oryzae, and conventional purchase is sufficient.

[0049] As an embodiment, the present invention mixes the citrus peel fermentation substrate and the seed liquid of Aspergillus to obtain the first fermentation material. As an embodiment, the present invention inoculates the activated Aspergillus into the first fermentation medium for the first fermentation culture to obtain the seed liquid of Aspergillus. As an embodiment, the mass ratio of the citrus peel fermentation substrate and the seed liquid of Aspergillus of the present invention is 1-1.2kg:10-15g; as another embodiment, the mass ratio of the citrus peel fermentation substrate and the seed liquid of Aspergillus of the present invention is 1kg:10g. As an embodiment, the present invention inoculates Aspergillus into PDA medium for activation culture to obtain activated Aspergillus. As an embodiment, the first fermentation medium of the present invention includes 10-25wt.%, oat bran 20-45wt.% and water 30-70wt.%; as another embodiment, the first fermentation medium of the present invention includes 20wt.%, oat bran 40wt.% and water 40wt.%. The temperature of the first fermentation culture of the present invention is 28-32°C; as another embodiment, the temperature of the first fermentation culture of the present invention is 28°C. As an embodiment, the first fermentation culture time of the present invention is 4 to 6 days; as another embodiment, the first fermentation culture time of the present invention is 4 days. The first fermentation medium provided by the present invention can fully provide the nutrients required for the activation of Aspergillus seeds, effectively save costs, and can be propagated in large quantities.

[0050] As an embodiment, the Aspergillus niger of the present invention may be the Aspergillus niger with a deposit number of CCTCC AF 200036. As an embodiment, the Aspergillus oryzae of the present invention may be the Aspergillus oryzae with a deposit number of CCTCCAF 200035. The present invention utilizes Aspergillus to ferment citrus peels, and the hydrolases produced by the fermentation of Aspergillus, such as pectinase, protease, cellulase, etc., can fully decompose pectin and fiber in the citrus peels, and the decomposition and utilization rates of pectin and fiber in the citrus peels are respectively more than 60%; and the present invention utilizes Aspergillus niger and / or Aspergillus oryzae, which has the advantages of high enzyme production efficiency, rich enzyme types, good safety, etc. compared with other Aspergillus.

[0051] As an embodiment, the present invention squeezes citrus pulp and filters to obtain citrus juice. As an embodiment, the filtration uses a 40-mesh filter. The present invention squeezes and filters citrus pulp, which can effectively remove impurities and precipitation in the juice, while fully retaining the nutrients in the juice.

[0052] As an embodiment, after obtaining the citrus juice, the present invention mixes the citrus juice with lactobacillus to obtain a second fermentation material. As an embodiment, the ratio of the mass of the citrus juice to the number of live lactobacilli of the present invention is 1-1.5 g: 1×10 7 ~1×10 9 CFU; As another embodiment, the ratio of the mass of the citrus juice of the present invention to the number of viable Lactobacillus is 1-1.5 g: 1×10 8 ~1×10 9 CFU; As another embodiment, the ratio of the mass of the citrus juice of the present invention to the number of viable Lactobacillus is 1g:1×10 9 CFU.

[0053] As an embodiment, the present invention mixes the citrus juice and the seed liquid of lactobacillus to obtain the first fermentation material. As an embodiment, the present invention inoculates the activated lactobacillus into the second fermentation medium for the second fermentation culture to obtain the seed liquid of lactobacillus. As an embodiment, the present invention inoculates lactobacillus into MRS medium for activation culture to obtain activated lactobacillus. As an embodiment, the second fermentation medium of the present invention includes MRS medium. As an embodiment, the temperature of the second fermentation culture of the present invention is 34-37°C; as another embodiment, the temperature of the second fermentation culture of the present invention is 37°C. As an embodiment, the time of the second fermentation culture of the present invention is 4-6h; as another embodiment, the time of the second fermentation culture of the present invention is 4h. The second fermentation medium provided by the present invention can fully provide the nutrients required for the activation of lactobacillus seeds, effectively save costs, and can be propagated in large quantities.

[0054] As an embodiment, the lactobacillus of the present invention includes Lactobacillus acidophilus. The present invention has no strict requirements on the source of the Lactobacillus acidophilus, and conventional purchase is sufficient. As an embodiment, the Lactobacillus acidophilus of the present invention can be the Lactobacillus acidophilus with a preservation number of CCTCC AB 2010208. The present invention utilizes lactobacillus to ferment citrus juice, which has the advantages of enhancing nutritional value, improving juice flavor and improving biological activity; and Lactobacillus acidophilus can better adapt to the matrix fermentation environment than other lactobacilli, further enrich the secondary metabolites of juice, and improve the nutritional and health value of juice.

[0055] After obtaining the first fermentation material and the second fermentation material, the first fermentation material is subjected to a first fermentation, and the second fermentation material is subjected to a second fermentation; the first fermentation and the second fermentation are carried out simultaneously, and during the first fermentation and the second fermentation, the fermentation product of the first fermentation material is subjected to solid-liquid separation, and the generated liquid material is mixed and fermented with the fermentation product of the second fermentation material. The temperature of the first fermentation of the present invention is 28 to 32°C. As an embodiment, the temperature of the first fermentation material of the present invention is 30°C. The temperature of the second fermentation material of the present invention is 34 to 37°C. The temperature of the mixed fermentation of the present invention is 34 to 35°C.

[0056] As one embodiment, the present invention performs solid-liquid separation on the fermentation product of the first fermentation material at 1 / 3 to 1 / 2 and 2 / 3 to 3 / 4 of the fermentation cycle of the first fermentation; as another embodiment, the present invention performs solid-liquid separation on the fermentation product of the first fermentation material at 1 / 3 and 2 / 3 of the fermentation cycle of the first fermentation. As one embodiment, the fermentation cycles of the first fermentation and the second fermentation are 6 to 8 days respectively; as one embodiment, the fermentation cycles of the first fermentation and the second fermentation are 6 days respectively. The present invention has no strict requirements on the method of solid-liquid separation, and conventional methods in the field, such as filtration, can be used. In the present invention, the citrus peel and citrus pulp are fermented simultaneously to avoid mutual inhibition between Aspergillus and Lactobacillus, thereby ensuring the fermentation efficiency of both; the liquid fermentation product produced by the fermentation of citrus peel is mixed with the citrus pulp to achieve the mixing of metabolites, which can enhance the fermentation effect of the citrus pulp.

[0057] As an embodiment, the first fermentation and the second fermentation of the present invention are carried out in a fermentation device; the fermentation device includes a fermentation tank, a stirring mechanism and a heating mechanism 7; the heating mechanism 7 is arranged on the inner side wall of the fermentation tank; a reversible hole-shaped mechanism 6 is arranged horizontally inside the fermentation tank, and the reversible hole-shaped mechanism 6 divides the fermentation tank into an upper fermentation tank and a lower fermentation tank; the upper fermentation tank carries out the first fermentation; the lower fermentation tank carries out the second fermentation; the reversible hole-shaped mechanism 6 is arranged on a side close to the upper fermentation tank; the filtering mechanism is arranged close to the upper fermentation tank A retractable mechanism 13 is provided on one side of the fermentation tank, which runs through the fermentation tank horizontally. When the retractable mechanism 13 is opened, the liquid material produced by the upper fermentation tank passes through the filtering mechanism and the reversible hole mechanism 6 and enters the lower fermentation tank; the upper fermentation tank is provided with an upper feed port 1, a pressure detection mechanism 5 and a temperature detection mechanism 10; the lower fermentation tank is provided with a lower feed port 11, a slag discharge port 8, a liquid discharge port 9 and a temperature detection mechanism 10; the stirring mechanism vertically runs through the upper fermentation tank, and the bottom of the stirring mechanism is suspended on the lower surface of the lower fermentation tank. As an embodiment, the upper fermentation tank of the present invention is also provided with a pressurizing mechanism 12; as an embodiment, the pressurizing mechanism 12 of the present invention includes but is not limited to a pressurizing pump. As an embodiment, the retractable mechanism 13 of the present invention includes but is not limited to a retractable baffle. The retractable mechanism 13 of the present invention spatially isolates the upper fermentation tank and the lower fermentation tank. When mixed fermentation is performed, the retractable mechanism 13 is turned on, and when fermentation is performed alone, the retractable mechanism 13 is closed.

[0058] As an embodiment, the aperture of the reversible porous mechanism 6 of the present invention is 2-3 mm; as another embodiment, the aperture of the reversible porous mechanism 6 of the present invention is 2 mm; as an embodiment, the filtering mechanism includes a filter screen. As an embodiment, the porosity of the filter screen is 0.4-0.6 μm; as another embodiment, the porosity of the filter screen is 0.5 μm. As an embodiment, the reversible porous mechanism 6 of the present invention includes a reversible porous partition.

[0059] As an embodiment, the heating mechanism 7 of the present invention includes but is not limited to heating resistance wires and electric heating tubes. As an embodiment, the pressure detection mechanism 5 of the present invention includes but is not limited to pressure gauges and pressure sensors. As an embodiment, the temperature detection mechanism 10 of the present invention includes but is not limited to temperature sensors and thermometers. As an embodiment, the liquid discharge port 9 of the present invention is connected to a storage mechanism pipeline. As an embodiment, the storage mechanism of the present invention includes but is not limited to a liquid storage tank and a batching tank.

[0060] As an embodiment, the stirring mechanism of the present invention includes a power mechanism 2 and a propeller 4; the power mechanism 2 and the propeller 4 are connected by a connecting shaft 3; the propeller 4 includes an upper propeller and a lower propeller; the upper propeller is located at the bottom of the upper fermentation tank; the lower propeller is located in the middle of the lower fermentation tank. As an embodiment, the power mechanism 2 of the present invention includes a motor. As an embodiment, the power mechanism 2 of the present invention is located on one side of the connecting shaft 3 close to the upper fermentation tank. As an embodiment, the retractable mechanism 13 of the present invention is located between the upper propeller and the filtering mechanism.

[0061] The present invention designs the above-mentioned fermentation device, and divides the fermentation tank into upper and lower parts through the reversible hole mechanism 6, so that the upper fermentation of citrus peel and the lower fermentation of citrus pulp can be carried out simultaneously, and the liquid fermentation product of the upper fermentation passes through the filtering mechanism and the reversible hole mechanism into the lower fermentation by pressurized filtration.

[0062] The present invention also provides a fermentation device, comprising a fermentation tank, a stirring mechanism and a heating mechanism 7; the heating mechanism 7 is arranged on the inner side wall of the fermentation tank; a reversible hole-shaped mechanism 6 is horizontally arranged inside the fermentation tank, and the reversible hole-shaped mechanism 6 divides the fermentation tank into an upper fermentation tank and a lower fermentation tank; a filtering mechanism is laid on one side of the reversible hole-shaped mechanism 6 close to the upper fermentation tank;

[0063] The upper fermentation tank is provided with an upper feed inlet 1, a pressure detection mechanism 5 and a temperature detection mechanism 10; the lower fermentation tank is provided with a lower feed inlet 11, a slag discharge port 8, a liquid discharge port 9 and a temperature detection mechanism 10;

[0064] The stirring mechanism vertically penetrates the upper fermentation tank, and the bottom of the stirring mechanism is suspended on the lower surface of the lower fermentation tank.

[0065] The specific connection structure of the fermentation device of the present invention has been recorded above and will not be repeated here. The fermentation device provided by the present invention has a simple structure and can realize the whole fruit fermentation of citrus, that is, the upper fermentation tank is used to ferment the citrus peel, and the lower fermentation tank is used to ferment the citrus pulp, ensuring that each is fermented synchronously under suitable fermentation conditions, and avoiding direct contact and mutual inhibition between lactobacillus and aspergillus during the fermentation process, which affects the fermentation efficiency of both; it can also monitor the fermentation environment in real time, realize the mixing of the two fermentation products, and improve the fermentation efficiency.

[0066] In order to further illustrate the present invention, a method for co-fermenting citrus with Lactobacillus and Aspergillus and a device thereof provided by the present invention are described in detail below with reference to the accompanying drawings and examples, but they should not be construed as limiting the scope of protection of the present invention.

[0067] Example 1

[0068] A kind of Figure 1 The fermentation device shown includes a fermentation tank, a motor 2, a connecting shaft 3, a propeller 4, a pressure gauge 5, a reversible porous partition 6, a heating resistance wire 7, a slag discharge port 8, a drainage pump 9, a temperature sensor 10 and a pressure pump 12; the aperture of the reversible porous partition 6 is 2 mm;

[0069] The reversible porous partition 6 with the filter is arranged in the middle of the fermenter, and the fermenter is divided into two parts, an upper fermenter and a lower fermenter. The filter is laid on the side of the reversible porous partition 6 close to the upper fermenter, and the porosity of the filter is 0.6 μm;

[0070] A pressure pump 12 is provided on the top of the upper fermentation tank; both the upper fermentation tank and the lower fermentation tank are provided with a feed port 1; the stirring shaft 3 passes through the upper fermentation tank, and the bottom of the stirring shaft 3 is suspended on the lower surface of the lower fermentation tank; the motor 2 is provided on the side of the stirring shaft 3 away from the lower fermentation tank;

[0071] The propeller 4 is arranged at the bottom of the stirring shaft 3 in the upper fermentation tank; the propeller 4 is arranged in the middle of the stirring shaft 3 in the lower fermentation tank; the pressure gauge 5 is arranged in the upper fermentation tank; the slag discharge port 8 and the drainage pump 9 are arranged at the bottom of the lower fermentation tank; the other end of the drainage pump 9 can be connected to the liquid storage tank; a retractable baffle is arranged between the propeller 4 and the filter screen in the upper fermentation tank, and horizontally penetrates the fermentation tank;

[0072] The temperature sensors 10 are respectively arranged on the upper surface of the upper fermentation tank and the lower surface of the flip-over porous partition 6 with filter screen; the heating resistance wires 7 are respectively arranged on the surrounding side walls of the upper fermentation tank and the lower fermentation tank.

[0073] Example 2

[0074] The fermentation method of citrus consists of the following steps:

[0075] 1. Fermentation substrate treatment

[0076] The whole citrus fruit was ultrasonically cleaned to remove residual pesticides and dirt on the surface, and the citrus peel and citrus pulp were separated; the citrus peel was crushed by a roller press (purchased from Jiangxi Longzhong Machinery Equipment Co., Ltd., product model FYSG300*300), and the diameter of the crushed peel was about 5 mm. The peel and water were mixed in a ratio of 1:2 to obtain a citrus peel fermentation matrix; the citrus pulp was conventionally squeezed by a juicer (purchased from Ningbo Corning Technology Co., Ltd., product model LT-03A-2350), and filtered with a 40-mesh filter to obtain citrus juice, that is, a citrus pulp fermentation matrix.

[0077] 2. Bacteria Activation and Seed Solution Preparation

[0078] (1) Aspergillus niger (purchased from China Center for Type Culture Collection, with the collection number of CCTCCAF200036) was activated on a PDA plate. After activation, spores were collected with distilled water to obtain 1×10 10 CFU / mL of spore suspension, and then inoculate the spore suspension into a culture matrix (20wt.%, soybean meal, 40wt.%, oat bran and 40wt.%, water, sterilized at 121°C for 15min) at a ratio of 5mL / 10kg, and culture at 28°C for 4d to obtain Aspergillus niger seed liquid.

[0079] (2) Using an inoculation loop, pick up Lactobacillus acidophilus stored on a slant (purchased from China Center for Type Culture Collection, with a collection number of CCTCCAB 2010208, disclosed in Chinese patent CN110651979A), inoculate it into MRS medium, and culture it at 37°C with shaking for 4 h to obtain a primary bacterial suspension; the primary bacterial suspension was inoculated into MRS medium at a volume ratio of 1:10, and the shaking culture was continued for 4 h for secondary expansion to obtain a Lactobacillus acidophilus seed liquid.

[0080] 3. Fermentation was carried out using the fermentation device of Example 1, and the specific steps were as follows:

[0081] (1) the citrus peel fermentation matrix obtained in step 1 is introduced into the upper fermentation tank of the fermentation device through the upper feed port, and the Aspergillus niger seed liquid obtained in step 2 is inoculated at an inoculum amount of 10 g / kg;

[0082] The citrus pulp fermentation matrix obtained in step 1 enters the lower fermentation tank of the fermentation device through the lower feed port and is heated at a rate of 1×10 9 CFU / g inoculation amount, inoculated with the Lactobacillus acidophilus seed solution obtained in step 2;

[0083] (2) The heating resistor wire was adjusted so that the temperature of the upper fermentation tank was 28°C and the temperature of the lower fermentation tank was 35°C. Solid-liquid co-fermentation was carried out for 6 days. During the fermentation process, the speed of the stirring shaft and the propeller was adjusted to 300 rpm by the motor.

[0084] (3) At 2d and 4d of fermentation in the upper fermenter, respectively, the fermentation product of the upper fermenter (rich in proteases and hydrolases produced by Aspergillus fermentation) was injected into the lower fermenter by pressurizing (0.15-0.20 MPa) for mixed fermentation.

[0085] (4) After the fermentation is completed, the fermentation product is collected by the liquid discharge pump of the lower fermentation tank, and the filter residue of the upper fermentation tank is turned over by turning over the reversible porous partition with filter screen to enter the lower fermentation tank and be discharged through the residue discharge port.

[0086] Example 3

[0087] A citrus fermentation method similar to Example 2, the only difference being that Aspergillus niger is replaced by Aspergillus oryzae (purchased from China Center for Type Culture Collection, with a collection number of CCTCCAF 200035). The fermentation conditions and control process of Aspergillus oryzae are consistent with those of Aspergillus niger.

[0088] Comparative Example 1

[0089] A citrus fermentation method similar to Example 2, the only difference being that step (3) is not performed, that is, during the fermentation process, no pressurization is performed, and the fermentation product of the upper fermentation tank and the product of the lower fermentation tank are not mixed for fermentation.

[0090] Test Example 1

[0091] (1) Referring to NY / T 2016-2011 "Spectrophotometric method for determination of pectin content in fruits and their products" and GB / T5009.10-2003 "Determination of crude fiber in plant foods", the pectin and fiber contents of the citrus peel residues discharged from the residue outlet of Examples 2 and 3 and Comparative Example 1 were respectively detected, and the decomposition rates of pectin and fiber were calculated. The results showed that after the upper layer fermentation of the citrus peel in Example 2, the decomposition rates of pectin and fiber reached 61.5% and 60.2% respectively; after the upper layer fermentation of the citrus peel in Example 3, the decomposition rates of pectin and fiber reached 67.0% and 60.8% respectively; after the upper layer fermentation of the citrus peel in Comparative Example 1, the decomposition rates of pectin and fiber reached 5.5% and 3.2% respectively.

[0092] (2) Referring to NY / T 2010-2011 "Determination of total flavonoids in citrus fruits and products" and "Determination of total phenols in fruits [J]. Modern Food, 2023, 29(24): 194-196.", the active ingredients of the fermentation products collected by the liquid discharge pump in Examples 2 and 3 and Comparative Example 1 were detected respectively. The results showed that the flavonoid content in the fermentation product collected by the liquid discharge pump in Example 2 reached 1.02 mg / mL, and the polyphenol content reached 1.44 mg / mL; the flavonoid content in the fermentation product collected by the liquid discharge pump in Example 3 reached 1.06 mg / mL, and the polyphenol content reached 1.37 mg / mL; the flavonoid content in the fermentation product collected by the liquid discharge pump in Comparative Example 1 reached 0.66 mg / mL, and the polyphenol content reached 0.95 mg / mL.

[0093] (3) Referring to NY / T 2014-2011 "Determination of the content of hesperidin and naringin in citrus fruits and products", the flavor components of the fermentation products collected by the liquid discharge pump in Examples 2 and 3 and Comparative Example 1 were respectively detected. The results showed that the content of the bitter substance naringin in the fermentation product collected by the liquid discharge pump in Example 2 reached 35.70 mg / L, and the comprehensive degradation rate was 48.3%; the content of the bitter substance naringin in the fermentation product collected by the liquid discharge pump in Example 3 reached 38.36 mg / L, and the comprehensive degradation rate was 45.1%; the content of the bitter substance naringin in the fermentation product collected by the liquid discharge pump in Comparative Example 1 reached 51.73 mg / L, and the degradation rate was 12.1%.

[0094] According to the above content, it can be seen that the technical scheme provided by the present invention can realize the whole-fruit fermentation of citrus, with a short fermentation cycle and high fermentation efficiency. The decomposition and utilization rates of citrus peel cellulose and pectin are respectively more than 60%, the flavonoids in the citrus pulp fermentation product are increased by more than 55%, the degradation rate of the bitter substance naringin is more than 45%, and the flavor of the fermented product is improved.

[0095] Although the above embodiment describes the present invention in detail, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A citrus fermentation method, characterized in that: The steps include: Mixing crushed citrus peels, water and Aspergillus niger to obtain a first fermentation material; mixing citrus juice obtained by squeezing citrus pulp with lactobacillus to obtain a second fermentation material; Performing a first fermentation on the first fermentation material; the temperature of the first fermentation is 28-32° C.; Performing a second fermentation on the second fermentation material; the temperature of the second fermentation is 34-37° C.; The first fermentation and the second fermentation are carried out simultaneously. During the first fermentation and the second fermentation, the fermentation product of the first fermentation material is separated into solid and liquid, and the generated liquid material is mixed and fermented with the fermentation product of the second fermentation material; the temperature of the mixed fermentation is 34-35°C.

2. The fermentation method according to claim 1, characterized in that The time of the solid-liquid separation is 1 / 3 to 1 / 2 and 2 / 3 to 3 / 4 of the fermentation cycle of the first fermentation.

3. The fermentation method according to claim 1 or 2, characterized in that: The fermentation periods of the first fermentation and the second fermentation are 6 to 8 days respectively.

4. The fermentation method according to claim 1, characterized in that The ratio of the total mass of the crushed citrus peel and water to the number of live bacteria of the Aspergillus is 1-1.2 kg: 1×10 10 ~1×10 11 CFU; The ratio of the mass of the citrus juice to the number of viable lactobacilli is 1-1.5 g: 1×10 7 ~1×10 9 CFU.

5. The fermentation method according to claim 1 or 4, characterized in that: The Aspergillus includes Aspergillus niger and / or Aspergillus oryzae; the Lactobacillus includes Lactobacillus acidophilus.

6. The fermentation method according to claim 1, characterized in that The first fermentation and the second fermentation are carried out in a fermentation device; the fermentation device comprises a fermentation tank, a stirring mechanism and a heating mechanism (7); the heating mechanism (7) is arranged on the inner wall of the fermentation tank; A reversible hole-shaped mechanism (6) is horizontally arranged inside the fermentation tank, and the reversible hole-shaped mechanism (6) divides the fermentation tank into an upper fermentation tank and a lower fermentation tank; the upper fermentation tank performs the first fermentation; and the lower fermentation tank performs the second fermentation; A filtering mechanism is provided on the side of the reversible hole-shaped mechanism (6) close to the upper fermentation tank; a drawable mechanism (13) is provided on the side of the filtering mechanism close to the upper fermentation tank, horizontally penetrating the fermentation tank; when the drawable mechanism (13) is opened, liquid material produced by the upper fermentation tank passes through the filtering mechanism and the reversible hole-shaped mechanism (6) and enters the lower fermentation tank; The upper fermentation tank is provided with an upper feed inlet (1), a pressure detection mechanism (5) and a temperature detection mechanism (10); the lower fermentation tank is provided with a lower feed inlet (11), a slag discharge port (8), a liquid discharge port (9) and a temperature detection mechanism (10); The stirring mechanism vertically penetrates the upper fermentation tank, and the bottom of the stirring mechanism is suspended on the lower surface of the lower fermentation tank.

7. The fermentation method according to claim 6, characterized in that The stirring mechanism comprises a power mechanism (2) and a propeller (4); the power mechanism (2) and the propeller (4) are connected via a connecting shaft (3); The propeller (4) comprises an upper propeller and a lower propeller; the upper propeller is located at the bottom of the upper fermentation tank; the lower propeller is located in the middle of the lower fermentation tank; The withdrawable mechanism (13) is located between the upper propeller and the filtering mechanism.

8. The fermentation method according to claim 6, characterized in that The aperture of the reversible hole-shaped structure (6) is 2 mm, the porosity is 70% to 75%, and the aperture is evenly distributed on the reversible hole-shaped structure (6); The filtering mechanism comprises a filter screen, and the porosity of the filter screen is 0.4-0.6 μm.

9. A fermentation device, comprising a fermentation tank, a stirring mechanism and a heating mechanism (7); the heating mechanism (7) is arranged on the inner wall of the fermentation tank; A reversible hole-shaped mechanism (6) is horizontally arranged inside the fermentation tank, and the reversible hole-shaped mechanism (6) divides the fermentation tank into an upper fermentation tank and a lower fermentation tank; a filtering mechanism is laid on the side of the reversible hole-shaped mechanism (6) close to the upper fermentation tank; a drawable mechanism (13) is arranged on the side of the filtering mechanism close to the upper fermentation tank, and horizontally penetrates the fermentation tank; when the drawable mechanism (13) is opened, liquid material produced by the upper fermentation tank passes through the filtering mechanism and the reversible hole-shaped mechanism (6) and enters the lower fermentation tank; The upper fermentation tank is provided with an upper feed inlet (1), a pressure detection mechanism (5) and a temperature detection mechanism (10); the lower fermentation tank is provided with a lower feed inlet (11), a slag discharge port (8), a liquid discharge port (9) and a temperature detection mechanism (10); The stirring mechanism vertically penetrates the upper fermentation tank, and the bottom of the stirring mechanism is suspended on the lower surface of the lower fermentation tank.

10. The fermentation device according to claim 9, characterized in that: The stirring mechanism comprises a power mechanism (2) and a propeller (4); the power mechanism (2) and the propeller (4) are connected via a connecting shaft (3); The propeller (4) comprises an upper propeller and a lower propeller; the upper propeller is located at the bottom of the upper fermentation tank; the lower propeller is located in the middle of the lower fermentation tank; The drawable mechanism (13) is located between the upper propeller and the filtering mechanism; The aperture of the reversible hole-shaped structure (6) is 2 mm, the porosity is 70% to 75%, and the aperture is evenly distributed on the reversible hole-shaped structure (6); The filtering mechanism comprises a filter screen, and the porosity of the filter screen is 0.4-0.6 μm.

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