Preparation method of mulberry leaf pickled cabbage

Abstract

The invention discloses a method for preparing mulberry leaf sauerkraut, which comprises culturing a fermented yeast liquid with lactic acid bacteria to a pH value of less than 5, adding washed and dried mulberry leaves, soaking the mulberry leaves in the fermented yeast liquid, placing them in a cool place, and sealing and fermenting them in a vacuum fermentation or inert gas environment until the pH value of the fermented liquid is 2-4, and then continuing to ferment for 15-48 hours. The present invention is fermented by using lactic acid bacteria as fermentation strains and culturing the fermented yeast liquid to a pH value of less than 5, which helps to reduce the nitrite content of the product. The present invention further sterilizes and dehydrates the fermented mulberry leaf sauerkraut product, and then sprays dehydroascorbic acid or ascorbic acid powder to mix, which is beneficial to the degradation of residual nitrite during storage.

Description

Technical Field

[0001] The invention relates to the technical field of pickled cabbage food, and more specifically to a method for preparing mulberry leaf pickled cabbage. Background Art

[0002] Mulberry leaves are rich in nutrients and are often used for raising silkworms or cooking mulberry leaf dishes. When mulberry leaves are used for cooking mulberry leaf dishes, they need to be freshly picked, which is inconvenient to store, and the dishes are single. In response to this, the applicant has developed a health-care mulberry leaf sauerkraut (publication number: CN106235161A) in the early stage, which is made of mulberry leaves as raw materials and lactic acid bacteria as fermentation strains, and is fermented and pickled. After continued production research, it was found that the mulberry leaf sauerkraut prepared in the early stage, after fermentation and pickling for 5 to 10 days, was dehydrated and vacuum-packed, and the acidity was uncontrollable, the nitrite was high, and with the increase of storage time, the nitrite had an increasing trend, which was not conducive to eating. Summary of the invention

[0003] An object of the present invention is to solve at least the above problems and to provide at least the advantages which will be described hereinafter.

[0004] The present invention uses lactic acid bacteria as fermentation strains and culture the fermentation liquid with a pH value of less than 5 for fermentation, which helps to reduce the formation of nitrite during the fermentation process, and can quickly make the pH value of the fermentation liquid reach 2-4, tending to fermentation stability, and then continue fermentation for 15-48 hours to promote nitrite degradation and further reduce the nitrite content, thereby improving the fermentation efficiency of mulberry leaf sauerkraut and reducing the nitrite content of the product.

[0005] In order to achieve these purposes and other advantages according to the present invention, the present invention provides a method for preparing mulberry leaf sauerkraut, which comprises culturing a fermented yeast solution with lactic acid bacteria until the pH value is less than 5, adding washed and dried mulberry leaves, soaking the mulberry leaves in the fermented yeast solution, placing them in a cool place, and performing vacuum fermentation or sealed fermentation in an inert gas environment until the pH value of the fermented solution reaches 2-4, and then continuing the fermentation for 15-48 hours.

[0006] Preferably, the fermented yeast liquid is prepared by the following method: firstly, the non-metal pickling container and the rice washing water are sterilized by microwave, after cooling to 25-35° C., 0.1-0.2wt% of lactic acid fermentation bacteria powder is added to the rice washing water, and the fermentation is carried out in a vacuum sealed state until the pH value of the fermented yeast liquid is less than 5.

[0007] Preferably, the method for washing and drying the mulberry leaves is as follows: the fresh mulberry leaves are soaked and washed in 1-1.5% salt water for 20-30 minutes, and then taken out and dried to make the water content of the mulberry leaves 60-70%.

[0008] Preferably, after continuing the fermentation for 15-48 hours, the process further comprises sterilizing and dehydrating the mulberry leaf sauerkraut to make the water content of the mulberry leaf sauerkraut 40-55%, spraying 0.01-0.05wt% of dehydroascorbic acid or ascorbic acid powder on the mulberry leaf sauerkraut, mixing, vacuum packaging or inert gas packaging, and storing in the dark.

[0009] Preferably, the average concentration of negative hydrogen ion gas mixed in the inert gas packaging is 1×10 3 ~1×10 6 Pieces / cm 3 The mass volume ratio of mulberry leaf sauerkraut packed in inert gas to gas is 1kg:1-4cm 3 .

[0010] Preferably, edible salt is added to the yeast solution when mulberry leaves are added, and the mass ratio of the yeast solution to the edible salt is 25:1-2.

[0011] Preferably, white wine is added to the yeast solution when mulberry leaves are added, and the mass ratio of the yeast solution to the 38-40 degree white wine is 1000:3-5.

[0012] Preferably, the fresh mulberry leaves are leaves of mulberry buds or new shoots with more than 12 leaves.

[0013] Preferably, the cool place is a light-proof environment at 25-30°C.

[0014] The present invention has at least the following beneficial effects:

[0015] First, the present invention uses lactic acid bacteria as the fermentation bacteria and cultivates the fermentation liquid with a pH value of less than 5 for fermentation, which helps to reduce the formation of nitrite during the fermentation process of mulberry leaf sauerkraut, and can quickly make the pH value of the fermentation liquid reach 2-4, tending to fermentation stability, and continue fermentation for 15-48 hours to promote nitrite degradation and further reduce the nitrite content, which can not only improve the fermentation efficiency of mulberry leaf sauerkraut, but also reduce the nitrite content of the product.

[0016] Second, the present invention sterilizes the non-metal pickling container and the rice washing water with microwaves, cools it to 25-35°C, adds lactic acid fermentation bacteria powder and mixes and ferments until the pH value of the yeast liquid is less than 5, thereby reducing the growth of yeast, Enterobacter and Flavobacterium and other bacteria, better cultivating lactic acid bacteria as fermentation strains, and helping to reduce the formation of nitrite during the fermentation process.

[0017] Third, the present invention sterilizes and dehydrates the fermented mulberry leaf sauerkraut, and then sprays 0.01-0.05wt% of dehydroascorbic acid or ascorbic acid powder on the mulberry leaf sauerkraut to mix well, which is beneficial to the degradation of residual nitrite during the storage process.

[0018] Fourth, the present invention uses an inert gas to pack the dehydrated mulberry leaf pickled cabbage, and the average concentration of negative hydrogen ion gas mixed in is 1×10 3 ~1×10 6 Pieces / cm 3 , which is conducive to packaging mulberry leaf sauerkraut with different acidity to meet customers' needs for different tastes of sauerkraut.

[0019] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. DETAILED DESCRIPTION

[0020] The present invention is further described in detail below in conjunction with embodiments so that those skilled in the art can implement the invention with reference to the description.

[0021] It should be understood that terms such as “having”, “including” and “comprising” used herein do not specify the existence or addition of one or more other elements or combinations thereof.

[0022] It should be noted that the experimental methods described in the following embodiments are conventional methods unless otherwise specified, and the reagents and materials can be obtained from commercial channels unless otherwise specified.

[0023] <Example 1>

[0024] The preparation method of mulberry leaf pickled cabbage comprises:

[0025] (1) Pick fresh mulberry leaves (leafs above the 12th leaf position of mulberry buds or new shoots, which are neither aged nor hardened), soak and wash them in 1.5% salt water for 30 minutes, pick them up and air-dry them for about 1 day, so that the water content of the mulberry leaves is 70%, which can not only clean and disinfect the mulberry leaves, but also soften and dry the water of the mulberry leaves, thus making them suitable for drying;

[0026] (2) taking a non-metal pickled container (ceramic jar), filling a small half jar of rice washing water, placing it in a microwave sterilization device, and microwave sterilizing for about 10 minutes, then cooling it to 35° C., adding lactic acid fermentation bacteria powder accounting for 0.2 wt % of the rice washing water and mixing it with the rice washing water, and vacuum sealing and fermenting until the pH value of the fermentation liquid is about 4.5, to obtain a fermentation liquid;

[0027] (3) Add appropriate amount of dry mulberry leaves to the fermentation liquid in the ceramic jar. The amount of mulberry leaves added should be sufficient to be completely soaked in the fermentation liquid. A ceramic mesh plate can be applied to the soaked surface of the mulberry leaves to press the mulberry leaves into the fermentation liquid to prevent the mulberry leaves from floating on the liquid surface and affecting the uniformity of quality.

[0028] (4) placing the ceramic jar soaked with mulberry leaves in a cool place (30°C environment away from light), sealing the ceramic jar and evacuating the interior for fermentation or evacuating the interior and then introducing inert gas, sealing and fermenting until the pH value of the fermentation liquid is 4, and then continuing the fermentation for 48 hours;

[0029] (5) Sterilize and dehydrate the fermented mulberry leaf sauerkraut to make the water content of the mulberry leaf sauerkraut 55%, then spray 0.05wt% of dehydrogenated ascorbic acid or ascorbic acid powder on the mulberry leaf sauerkraut and mix well. When packaging with inert gas, the average concentration of negative hydrogen ion gas mixed in is 1×10 6 Pieces / cm 3 The mass volume ratio of mulberry leaf sauerkraut packed in inert gas to gas is 1kg:4cm 3 , the package is kept at normal pressure and stored at room temperature away from light.

[0030] The fermented mulberry leaf sauerkraut product has the unique fragrance of mulberry leaves, bright color, dense texture, toughness when pinched, and crispy taste; after being stored at room temperature and away from light for 6 months, the above sensory effects have not changed.

[0031] <Example 2>

[0032] The preparation method of mulberry leaf pickled cabbage comprises:

[0033] (1) Pick fresh mulberry leaves (leafs above the 12th leaf position of mulberry buds or new shoots, which are neither aged nor hardened), soak and wash them in 1% salt water for 20 minutes, pick them up and air-dry them for about 1 day, so that the water content of the mulberry leaves is 60%, which can not only clean and disinfect the mulberry leaves, but also soften and dry the water of the mulberry leaves, and thus make them suitable for drying;

[0034] (2) taking a non-metal pickled container (ceramic jar), filling a small half jar of rice washing water, placing it in a microwave sterilization device, and microwave sterilizing for about 10 minutes, then cooling it to 25° C., adding lactic acid fermentation bacteria powder accounting for 0.1wt% of the rice washing water and mixing with the rice washing water, and vacuum sealing and fermenting until the pH value of the fermentation liquid is about 4, thereby obtaining a fermentation liquid;

[0035] (3) Adding appropriate amount of dry mulberry leaves, edible salt and liquor into the fermentation liquid in the ceramic jar, the amount of mulberry leaves added is based on the amount of mulberry leaves that can be completely soaked in the fermentation liquid, and a ceramic mesh plate can be applied to the soaked upper surface of the mulberry leaves to press the mulberry leaves into the fermentation liquid; the mass ratio of the fermentation liquid to the edible salt is 25:2, and the mass ratio of the fermentation liquid to the 38-degree liquor is 1000:5;

[0036] (4) Place the ceramic jar with the mulberry leaves soaked in a cool place (25°C environment away from light), seal the ceramic jar and evacuate the inside to ferment until the pH value of the fermentation liquid is 2, and continue fermenting for 15 hours;

[0037] (5) Sterilize and dehydrate the fermented mulberry leaf sauerkraut to make the water content of the mulberry leaf sauerkraut 40%, then spray 0.01wt% of dehydrogenated ascorbic acid powder on the mulberry leaf sauerkraut and mix well. When packaging with inert gas, the average concentration of negative hydrogen ion gas mixed in is 1×10 3 Pieces / cm 3 The mass volume ratio of mulberry leaf sauerkraut packed in inert gas to gas is 1kg:1cm 3 , the package is kept at normal pressure and stored at room temperature away from light.

[0038] The fermented mulberry leaf sauerkraut product has the unique fragrance of mulberry leaves, bright color, dense texture, toughness when pinched by hand, crispy and tender taste, and salty taste; after being stored at room temperature and away from light for 6 months, the above sensory effects have not changed.

[0039] <Example 3>

[0040] The preparation method of mulberry leaf pickled cabbage comprises:

[0041] (1) Pick fresh mulberry leaves (leafs above the 12th leaf position of mulberry buds or new shoots, which are neither aged nor hardened), soak and wash them in 1% salt water for 20 minutes, pick them up and air-dry them for about 1 day, so that the water content of the mulberry leaves is 60%, which can not only clean and disinfect the mulberry leaves, but also soften and dry the water of the mulberry leaves, and thus make them suitable for drying;

[0042] (2) taking a non-metal pickled container (ceramic jar), filling a small half jar of rice washing water, placing it in a microwave sterilization device, and microwave sterilizing for about 10 minutes, then cooling it to 25° C., adding lactic acid fermentation bacteria powder accounting for 0.1wt% of the rice washing water and mixing with the rice washing water, and vacuum sealing and fermenting until the pH value of the fermentation liquid is about 4.5, to obtain a fermentation liquid;

[0043] (3) Adding appropriate amount of dry mulberry leaves to the fermentation liquid in the ceramic cylinder, the amount of mulberry leaves added is based on the amount of mulberry leaves that can be completely soaked in the fermentation liquid, and a ceramic mesh plate can be applied to the soaked upper surface of the mulberry leaves to press the mulberry leaves into the fermentation liquid;

[0044] (4) Place the ceramic jar with the mulberry leaves soaked in a cool place (25°C environment away from light), seal the ceramic jar and evacuate the inside to ferment until the pH value of the fermentation liquid is 2, and continue fermenting for 15 hours;

[0045] (5) Sterilize and dehydrate the fermented mulberry leaf sauerkraut to make the water content of the mulberry leaf sauerkraut 40%, then spray ascorbic acid powder accounting for 0.01wt% of the mulberry leaf sauerkraut and mix well. When packaging with inert gas, the average concentration of negative hydrogen ion gas mixed in is 1×10 3 Pieces / cm 3 The mass volume ratio of mulberry leaf sauerkraut packed in inert gas to gas is 1kg:1cm 3 , the package is kept at normal pressure and stored at room temperature away from light.

[0046] The fermented mulberry leaf sauerkraut product has the unique fragrance of mulberry leaves, bright color, dense texture, toughness when pinched, and crispy taste; after being stored at room temperature and away from light for 6 months, the above sensory effects have not changed.

[0047] <Example 4>

[0048] The preparation method of mulberry leaf pickled cabbage comprises:

[0049] (1) Pick fresh mulberry leaves (leafs above the 12th leaf position of mulberry buds or new shoots, which are neither aged nor hardened), soak and wash them in 1% salt water for 20 minutes, pick them up and air-dry them for about 1 day, so that the water content of the mulberry leaves is 60%, which can not only clean and disinfect the mulberry leaves, but also soften and dry the water of the mulberry leaves, and thus make them suitable for drying;

[0050] (2) taking a non-metal pickled container (ceramic jar), filling a small half jar of rice washing water, placing it in a microwave sterilization device, and microwave sterilizing for about 10 minutes, then cooling it to 25° C., adding lactic acid fermentation bacteria powder accounting for 0.1wt% of the rice washing water and mixing with the rice washing water, and vacuum sealing and fermenting until the pH value of the fermentation liquid is about 4.5, to obtain a fermentation liquid;

[0051] (3) Adding appropriate amount of dry mulberry leaves to the fermentation liquid in the ceramic cylinder, the amount of mulberry leaves added is based on the amount of mulberry leaves that can be completely soaked in the fermentation liquid, and a ceramic mesh plate can be applied to the soaked upper surface of the mulberry leaves to press the mulberry leaves into the fermentation liquid;

[0052] (4) Place the ceramic jar with the mulberry leaves soaked in a cool place (25°C environment away from light), seal the ceramic jar and evacuate the inside to ferment until the pH value of the fermentation liquid is 2, and continue fermenting for 15 hours;

[0053] (5) Sterilize and dehydrate the fermented mulberry leaf sauerkraut to make the water content of the mulberry leaf sauerkraut 40%, then spray ascorbic acid powder accounting for 0.01wt% of the mulberry leaf sauerkraut and mix well. When packaging with inert gas, the average concentration of negative hydrogen ion gas mixed in is 1×10 6 Pieces / cm 3 The mass volume ratio of mulberry leaf sauerkraut packed in inert gas to gas is 1kg:1cm 3 , the package is kept at normal pressure and stored at room temperature away from light.

[0054] The fermented mulberry leaf sauerkraut product has the unique fragrance of mulberry leaves, bright color, dense texture, toughness when pinched, and crispy taste; after being stored at room temperature and away from light for 6 months, the above sensory effects have not changed.

[0055] <Comparative Example 1>

[0056] The preparation method of mulberry leaf pickled cabbage in this example is basically the same as that in Example 3, except that the fermentation liquid in step (2) is not fermented in advance. Step (2) specifically comprises: taking a non-metal pickling container (ceramic jar), filling a small half jar of rice washing water, placing it in a microwave sterilization device, and microwave sterilizing for about 10 minutes, then cooling it to 25°C, adding 0.1wt% of lactic acid fermentation bacteria powder to the rice washing water and mixing it with the rice washing water to obtain a fermentation liquid, and then step (3) adding the appropriate amount of dried mulberry leaves to the fermentation liquid in step (2).

[0057] <Comparative Example 2>

[0058] The preparation method of mulberry leaf sauerkraut in this example is basically the same as that in Example 3, the only difference being that ascorbic acid powder is not sprayed in step (5).

[0059] <Comparative Example 3>

[0060] The preparation method of mulberry leaf sauerkraut in this example is basically the same as that in Example 3, except that no negative hydrogen ion gas is mixed in the inert gas packaging in step (5). Step (5) is specifically as follows: sterilize and dehydrate the fermented mulberry leaf sauerkraut to make the water content of the mulberry leaf sauerkraut 40%, then spray ascorbic acid powder accounting for 0.01wt% of the mulberry leaf sauerkraut and mix well. The mass volume ratio of the mulberry leaf sauerkraut packaged in inert gas to the gas is 1kg:1cm 3 , the package is kept at normal pressure and stored at room temperature away from light.

[0061] <Test example>

[0062] The total acidity, nitrite content and total bacterial count of the mulberry leaf sauerkraut products fermented in step (4) of Examples 3-4 and Comparative Examples 1-3 (stage 1) and the mulberry leaf sauerkraut products stored for 6 months after step (5) (stage 2) were measured respectively. The measured data are shown in Table 1.

[0063] Among them, the total acidity determination method refers to GB / T 12456-2008 "Determination of total acid in food", take 10.00g of sauerkraut and grind it into a homogenate, dilute to 100mL with distilled water, filter and set aside, and use acid-base titration to determine the fermentation suspension; the nitrite content determination method is: take 500g of sauerkraut and grind it into a slurry, refer to GB 5009.33-2010 "Determination of nitrite and nitrate in food", prepare the nitrite extract of the sauerkraut sample, and use the naphthylethylenediamine hydrochloride method to determine the fermentation suspension, use the sodium nitrite content as the horizontal axis and the absorbance as the vertical axis, draw a standard curve, and perform determination and calculation; the total colony count is carried out with reference to the GB4789.2 inspection method.

[0064] Table 1:

[0065] Phase 1 Total acidity (g / kg) Nitrite content (mg / kg) Total colony count (CFU / g) Example 2 6.3 1.19 604 Example 3 6.1 1.14 730 Example 4 6.0 1.17 745 Comparative Example 1 6.2 1.46 801 Comparative Example 2 6.1 1.16 769 Comparative Example 3 6.1 1.13 754 Phase 2 Total acidity (g / kg) Nitrite content (mg / kg) Total colony count (CFU / g) Example 2 5.1 0.34 47 Example 3 5.2 0.33 40 Example 4 3.3 0.35 52 Comparative Example 1 5.0 0.36 50 Comparative Example 2 4.9 1.98 127 Comparative Example 3 6.3 0.32 109

[0066] The data in Table 1 show that the present invention uses lactic acid bacteria as the fermentation strain and cultivates the fermentation liquid with a pH value of less than 5 for fermentation, which helps to reduce the nitrite content of the product. The present invention further sterilizes and dehydrates the fermented mulberry leaf sauerkraut product, and then sprays dehydroascorbic acid or ascorbic acid powder to mix, which is conducive to the degradation of residual nitrite during storage. The total acidity of mulberry leaf sauerkraut tends to be stable at 6.3g / kg. Although high acidity helps to degrade nitrite, it is close to human gastric acid. Direct consumption will feel too sour and too irritating, and it is difficult to meet the needs of different tastes. The present invention mixes negative hydrogen ion gas during packaging, and packages mulberry leaf sauerkraut of different acidities by adjusting the amount of negative hydrogen ion gas mixed, so as to obtain satisfaction of different tastes. And according to the national mandatory standard GB2714-2003 "Sanitary Standards for Pickled Vegetables", the coliform group of mulberry leaf sauerkraut products in detection stage 1 and stage 2 does not exceed 30MPN / 100g, which meets the requirements of food safety. Furthermore, the present invention sprays dehydroascorbic acid or ascorbic acid powder on the mulberry leaf sauerkraut product in stage 1, and mixes the antioxidant gas and oxygen consumption of negative hydrogen ion gas to inhibit the growth of bacteria and mildew, which is beneficial to the effective preservation of the product.

[0067] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes, and they can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the examples shown and described herein.

Claims

1. A method for preparing mulberry leaf pickled cabbage, characterized in that: The method comprises culturing a fermentation liquid with lactic acid bacteria until the pH value thereof is less than 5, adding washed and dried mulberry leaves, soaking the mulberry leaves in the fermentation liquid, placing the leaves in a cool place, and performing vacuum fermentation or sealed fermentation in an inert gas environment until the pH value of the fermentation liquid reaches 2-4, and then continuing the fermentation for 15-48 hours; The fermented yeast liquid is prepared by the following method: firstly, a non-metal pickling container and the rice washing water are sterilized by microwave, after cooling to 25-35° C., 0.1-0.2 wt % of the lactic acid fermentation bacteria powder is added to the rice washing water, and the mixture is mixed with the rice washing water, and vacuum sealed and fermented until the pH value of the fermented yeast liquid is less than 5; Wherein, after continuing the fermentation for 15-48 hours, the method further comprises sterilizing and dehydrating the mulberry leaf sauerkraut to make the water content of the mulberry leaf sauerkraut be 40-55%, spraying 0.01-0.05 wt % of dehydroascorbic acid or ascorbic acid powder on the mulberry leaf sauerkraut, mixing, vacuum packaging or inert gas packaging, and storing in the dark; The average concentration of negative hydrogen ion gas mixed into the inert gas during packaging is 1×10 3 ~1×10 6 Pieces / cm 3 The mass volume ratio of mulberry leaf pickle packed in inert gas to gas is 1kg:1-4 cm 3 .

2. The method for preparing mulberry leaf sauerkraut according to claim 1, characterized in that: The method for washing and drying the mulberry leaves is as follows: the fresh mulberry leaves are put into 1-1.5% salt water, soaked and washed for 20-30 minutes, and then taken out and dried to make the water content of the mulberry leaves 60-70%.

3. The method for preparing mulberry leaf pickled cabbage according to claim 2, characterized in that: Edible salt is added to the yeast solution when the mulberry leaves are added, and the mass ratio of the yeast solution to the edible salt is 25:1-2.

4. The method for preparing mulberry leaf pickled cabbage according to claim 3, characterized in that: When adding mulberry leaves to the fermented yeast liquid, white wine is added, and the mass ratio of the fermented yeast liquid to the 38-40 degree white wine is 1000:3-5.

5. The method for preparing mulberry leaf sauerkraut according to any one of claims 1 to 4, characterized in that: Mulberry leaves are the leaves above the 12th leaf position of mulberry buds or new shoots.

6. The method for preparing mulberry leaf pickled cabbage according to claim 5, characterized in that: The cool place is a light-proof environment at 25-30°C.