Process for the preparation of a freeze-dried reconstituted red date product

Abstract

The application discloses a method for preparing a freeze-dried recombined red date product and belongs to the technical field of food processing. The raw materials for preparing the freeze-dried recombined red date product include red dates, chickpeas and quinoa. The method comprises the following steps: respectively performing softening and curing treatment on the raw materials, compounding the raw materials to obtain compounded raw materials, performing crushing treatment on the compounded raw materials to obtain crushed compounded raw materials, performing first fermentation treatment on the crushed compounded raw materials and yeast to obtain first fermentation products, performing second sterilization treatment on the first fermentation products, performing second fermentation treatment on the first fermentation products and lactic acid bacteria to obtain second fermentation products, and performing freeze-drying treatment on the second fermentation products to obtain the freeze-dried recombined red date product. The method improves the texture stability of the freeze-dried recombined red date product, and the obtained product has low hygroscopicity and hardness, good integrity, rich taste, moderate sourness and sweetness, rich aroma and high sensory quality.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of food processing, and particularly relates to a method for preparing a freeze-dried recombined red jujube product. BACKGROUND

[0002] Red jujube is rich in nutrients and has potential medical and health care properties, and is regarded as a pure natural medicine and important functional food resource. Drying is the main processing method for red jujube, and with the iterative development of the consumption demand for nutritious, healthy and delicious leisure food, vacuum freeze-drying technology has gradually become the main processing technology for preparing high-end leisure red jujube products.

[0003] Vacuum freeze-drying technology is a green and advanced food processing technology. Compared with traditional thermal drying technology, vacuum freeze-drying technology removes the water in the material in the form of sublimation in a low-temperature and vacuum environment, thereby maximizing the retention of the color and nutritional quality of the raw material. At the same time, with the removal of water, the macromolecular substances and small molecular compounds in the raw material can form a special porous or sponge structure of the freeze-dried food, thereby endowing the product with a unique texture.

[0004] Vacuum freeze-dried recombined red jujube products are leisure foods prepared by using red jujube as the main raw material and through a plurality of pretreatment processes such as crushing, pulping, homogenizing, mixing and reshaping. The products are favored by consumers because they well retain the quality characteristics (such as odor and taste) of fresh red jujube and have a unique crisp texture. However, due to the high sugar content of red jujube and the unique porous network structure of vacuum freeze-dried products, vacuum freeze-dried recombined red jujube products are prone to moisture absorption and breakage, which causes problems such as product texture collapse, color deterioration and collapse, thereby restricting the high-quality development of the products.

[0005] Therefore, how to improve the texture stability of vacuum freeze-dried recombined red jujube products, reduce the moisture absorption, improve the product integrity and improve the sensory quality to realize the quality improvement of the freeze-dried recombined red jujube products is a problem to be solved at present. SUMMARY

[0006] The present application aims to at least partially solve at least one of the technical problems existing in the prior art. To this end, the present application provides a method for preparing a freeze-dried recombined red jujube product. The method of the present application improves the texture stability of the freeze-dried recombined red jujube product, and the obtained product has low moisture absorption and hardness, good integrity, rich taste, moderate sweetness and sourness, rich aroma and high sensory quality.

[0007] It should be stated that the present application is completed based on the following findings of the inventors: the prior art improves the texture stability of food by adding macromolecular polymers (such as gum arabic, malt dextrin, soybean protein, etc.), which does not conform to the trend of pursuing clean labels in the food field.

[0008] In view of this, the inventors combined natural plant ingredients such as chickpeas and quinoa with red dates. They utilized the spontaneous interaction between the macromolecules (proteins, starches, and dietary fiber) in these plant ingredients and the highly hygroscopic small molecules (fructose and glucose) in the red dates to reduce the aggregation of small sugar molecules on the surface of the freeze-dried red date products, thereby lowering the product's hygroscopicity and hardness. Further experimental results showed that the freeze-dried reconstituted red date products prepared by combining chickpeas and quinoa with red dates exhibited significantly reduced hygroscopicity and hardness, and significantly improved textural stability.

[0009] The inventors discovered that fermentation by yeast and lactic acid bacteria can further reduce the content of the aforementioned small-molecule sugars and increase the content of lactic acid and acetic acid in the product, making the freeze-dried recombinant jujube products more flavorful and moderately sweet and sour. At the same time, lactic acid and acetic acid will be further converted into volatile flavor components, making the product more aromatic.

[0010] Therefore, this invention proposes a method for preparing freeze-dried recombinant jujube products. According to an embodiment of the invention, the raw materials for preparing the freeze-dried recombinant jujube products include: jujubes, chickpeas, and quinoa. The method includes: softening and cooking the raw materials respectively, then compounding them to obtain compound raw materials; crushing the compound raw materials to obtain crushed compound raw materials; subjecting the crushed compound raw materials to a first fermentation treatment with yeast to obtain a first fermented product; subjecting the first fermented product to a second sterilization treatment, then subjecting it to a second fermentation treatment with lactic acid bacteria to obtain a second fermented product; and freeze-drying the second fermented product to obtain the freeze-dried recombinant jujube products.

[0011] The method according to embodiments of the present invention improves the textural stability of freeze-dried recombinant jujube products. The resulting products have low hygroscopicity and hardness, good integrity, rich flavor, moderate sweetness and sourness, strong aroma, and high sensory quality. According to embodiments of the present invention, based on the total mass of the compound raw materials, the total content of the softened and cooked chickpeas and quinoa is 15-45%, preferably 25-35%, and more preferably 35%. The inventors obtained the above-mentioned optimal addition amount through extensive experiments. Within this content range, the hygroscopicity and hardness of the product are further reduced, exhibiting typical jujube flavor characteristics. Excessive addition of chickpeas and quinoa weakens the typical jujube flavor characteristics of the product, and the excessively viscous slurry hinders moisture diffusion and drying; insufficient addition of chickpeas and quinoa fails to effectively reduce the hygroscopicity and hardness of the product.

[0012] For example, the total content of chickpeas and quinoa can be 15% to 45%.

[0013] Preferably, the total content of chickpeas and quinoa can be 25-35%.

[0014] More preferably, the total content of chickpeas and quinoa is 35%. Therefore, the freeze-dried recombinant jujube product has the best quality, low hygroscopicity, and superior sensory qualities.

[0015] According to an embodiment of the present invention, based on the total mass of the compound raw materials, the mass ratio of the softened and cooked chickpeas to the quinoa is (1-3):(3-1), preferably (1-2):(2-1), and more preferably 2:1. The inventors obtained the above-mentioned optimal mass ratio through numerous experiments. Within this mass ratio range, the hygroscopicity of the product is further reduced, and the product has a good flavor.

[0016] Further research by the inventors revealed that as the proportion of quinoa increases, the product's hygroscopicity increases, while as the proportion of chickpeas increases, the product's hygroscopicity decreases, and the beany odor becomes stronger. Therefore, exemplarily, based on the total mass of the compound raw materials, the preferred mass ratio of softened and cooked chickpeas to quinoa is 1:2, 1:1, or 2:1, more preferably 2:1. This further reduces the product's hygroscopicity and improves its sensory quality.

[0017] According to an embodiment of the present invention, the final inoculation concentration of the yeast in the first fermentation treatment is 10. 9 ~10 10 The fermentation concentration is CFU / mL, the fermentation temperature is 20–37℃, preferably 28–30℃, and the fermentation time is 2–16 h, preferably 4–8 h. This improves fermentation efficiency, shortens the production cycle, and controls the flavor characteristics of the material.

[0018] According to an embodiment of the present invention, the yeast is *Saccharomyces cerevisiae*. This further increases the volatile flavor components and enriches the taste characteristics.

[0019] According to an embodiment of the present invention, in the second fermentation treatment, the final inoculation concentration of the lactic acid bacteria is 10. 7 ~10 8 The fermentation concentration is CFU / mL, the fermentation temperature is 30–38℃, preferably 36–38℃, and the fermentation time is 4–32 h, preferably 8–16 h. This improves fermentation efficiency, shortens the production cycle, enhances sweetness and acidity, and controls the flavor characteristics of the fermented material.

[0020] According to an embodiment of the present invention, the lactic acid bacteria are selected from at least one of Streptococcus thermophilus, Lactobacillus plantarum, Lactobacillus rhamnosus, Pediococcus pentosus, and Leuconostoc mesenteroides. This further increases volatile flavor components, enriches taste characteristics, and improves sweetness and acidity.

[0021] According to an embodiment of the present invention, the lactic acid bacteria consist of Streptococcus thermophilus, Lactobacillus plantarum, Lactobacillus rhamnosus, Pediococcus pentosus, and Leuconostoc mesenteroides. The resulting product has a rich flavor and intense aroma.

[0022] According to an embodiment of the present invention, the microbial ratio of *Streptococcus thermophilus*: *Lactobacillus plantarum*: *Lactobacillus rhamnosus*, *Pediococcus pentosus*, and *Leuconostoc mesenteroides* is 1:2:1:1:1. As a result, the product has a unique flavor, rich aroma, moderate sweetness and acidity, and high sensory quality.

[0023] According to an embodiment of the present invention, the temperature of the second sterilization treatment is 85°C, and the time is 10–30 min. According to the method of the present invention, this second sterilization treatment facilitates subsequent lactic acid bacteria fermentation, improves fermentation efficiency, and helps control the flavor characteristics of the fermented material.

[0024] In this paper, the temperature of the second sterilization treatment is the pasteurization temperature, thereby preserving the nutrients and quality characteristics of the raw materials to the greatest extent.

[0025] In this paper, the duration of the second sterilization treatment is determined based on the sterilization effect on the aforementioned yeast. The sterilization effect on the yeast is determined so as not to affect the fermentation efficiency of the second fermentation treatment or the flavor characteristics of the fermented material.

[0026] For example, the time for the second sterilization treatment can be 10 min, 15 min, 20 min, 25 min, or 30 min.

[0027] According to an embodiment of the present invention, the first fermentation process includes: subjecting the crushed compound raw materials to a first sterilization treatment, inoculating them with the yeast, and then fermenting; wherein the temperature of the first sterilization treatment is 85°C and the time is 10–30 min. This further improves the fermentation efficiency.

[0028] In this paper, the temperature of the first sterilization treatment is the pasteurization temperature, thereby preserving the nutrients and quality characteristics of the raw materials to the greatest extent.

[0029] In this paper, the duration of the first sterilization treatment is determined based on the sterilization effect on the microorganisms in the crushed compound raw materials. The sterilization effect on the microorganisms is determined so as not to affect the fermentation efficiency of the first fermentation treatment and the flavor characteristics of the fermented material.

[0030] For example, the time for the first sterilization treatment can be 10 min, 15 min, 20 min, 25 min, or 30 min.

[0031] According to an embodiment of the present invention, the freeze-drying process includes: pre-freezing and sublimation drying. The pre-freezing temperature is -80 to -60°C, preferably -80°C, and the time is 12 to 36 hours, preferably 24 hours. The sublimation drying temperature is -45 to -25°C, preferably -40°C, and the time is 24 to 72 hours, preferably 48 hours. The inventors determined the above-mentioned preferred freeze-drying conditions through extensive experiments. Under these experimental conditions, the product has a loose and porous network internal structure, and its textural stability and integrity are further improved.

[0032] According to an embodiment of the present invention, the softening and cooking process includes: cooking the red dates, chickpeas and quinoa separately, draining the water, and obtaining red dates, chickpeas and quinoa that have undergone softening and cooking.

[0033] According to an embodiment of the present invention, the cooking time is 5 to 40 minutes and the temperature is 100°C.

[0034] According to an embodiment of the present invention, the cooking time for the jujubes or chickpeas is 15 to 40 minutes, preferably 20 to 30 minutes, and the amount of water added is 2 to 6 times the mass of the jujubes or chickpeas, preferably 3 to 5 times.

[0035] According to an embodiment of the present invention, the cooking time of the quinoa is 5 to 25 minutes, preferably 5 to 15 minutes, and the amount of water added is 2 to 6 times the mass of the quinoa, preferably 3 to 5 times.

[0036] According to an embodiment of the present invention, the crushing process includes: adding water to the compound raw materials at a material-to-liquid ratio of 1:(1-4), and then grinding them in a blender for 3-5 minutes.

[0037] According to an embodiment of the present invention, the method further includes vacuum packaging the freeze-dried recombinant jujube product. This further extends the shelf life of the product.

[0038] According to an embodiment of the present invention, the vacuum packaging material is aluminum foil. This further maintains the product's quality characteristics and extends its shelf life.

[0039] It should be noted that the present invention does not strictly limit the shape of the freeze-dried recombinant jujube products. They can be spherical, flake, block, irregular, etc., and can be flexibly selected according to the actual situation.

[0040] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0041] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the description of the embodiments taken in conjunction with the following drawings, in which:

[0042] Figure 1 The effects of different amounts of chickpeas and quinoa added in Examples 1-5 of this invention on the hygroscopicity of freeze-dried recombinant jujube products;

[0043] Figure 2 The effect of different compound mass ratios of chickpeas and quinoa on the hygroscopicity of freeze-dried recombinant jujube products in Examples 3, 6-9 of this invention;

[0044] Figure 3 Comparison charts of moisture absorption rates based on orthogonal experiments for Embodiments 2, 3, 4, 6, 7, 10, 11, 12, and 13 of the present invention;

[0045] Figure 4 The sensory radar images based on orthogonal experiments in Embodiments 2, 3, 4, 6, 7, 10, 11, 12, and 13 of the present invention are shown.

[0046] Figure 5 These are color change diagrams of Embodiment 13 and Comparative Examples 1-4 of the present invention under different relative humidities;

[0047] Figure 6 The graphs are moisture absorption rate curves of Examples 13, 5, and 6 of the present invention under different relative humidities; wherein, (A) is the moisture absorption process created by saturated sodium nitrite solution (Aw = 0.610); (B) is the moisture absorption process created by saturated sodium chloride solution (Aw = 0.753); and (C) is the moisture absorption process created by saturated potassium chloride solution (Aw = 0.843). Detailed Implementation

[0048] The present invention will be explained below with reference to embodiments. Those skilled in the art will understand that the following embodiments are for illustrative purposes only and should not be considered as limiting the scope of the invention. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in the field or according to the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be obtained commercially.

[0049] Example 1

[0050] A method for preparing freeze-dried recombinant jujube products includes:

[0051] Step 1: Select plump, intact red dates, chickpeas, and quinoa that are free from insect damage. Add water to the red dates and chickpeas at a ratio of 1:4 (w / w) and cook at 100℃ for 25 minutes. Add water to the quinoa at a ratio of 1:4 (w / w) and cook at 100℃ for 10 minutes to allow them to absorb water, expand, soften, and cook. Then drain the water.

[0052] Step 2: Combine the softened and cooked chickpeas, quinoa, and red dates. The ratio of chickpeas to quinoa is fixed at 1:1 (w / w). Based on the total weight of chickpeas, quinoa, and red dates, add chickpeas and quinoa at a total of 20% (w / w) to the red dates. Then add water at a material-to-liquid ratio of 1:1.5 (w / w) and blend in a high-speed blender for 3 minutes to obtain a mixed pulp of red dates, chickpeas, and quinoa.

[0053] Step 3: Treat the above mixed slurry at 85℃ for 10 minutes to perform pasteurization.

[0054] Step 4: Inoculate the sterilized mixed slurry with yeast starter at an inoculum rate of 0.02% (v / v) and ferment at 30°C for 6 hours. The initial bacterial concentration of the starter is 10. 9 ~10 10 CFU / mL. After fermentation, the yeast was sterilized at 85℃ for 10 min to terminate the fermentation.

[0055] Step 5: Inoculate the sterilized mixed slurry with lactic acid bacteria starter at an inoculum rate of 3% (v / v) and ferment at 37°C for 12 hours. The starter consists of Streptococcus thermophilus, Lactobacillus plantarum, Lactobacillus rhamnosus, Pediococcus pentosus, and Leuconostoc mesenteroides in a ratio of 1:2:1:1:1, with an initial bacterial concentration of 10 μL for each lactic acid bacteria. 7 ~10 8 CFU / mL.

[0056] Step 6: Pour the fermented red dates, chickpeas and quinoa paste into a mold, pre-freeze at -80℃ for 24 hours, and then place it in a vacuum freeze-drying chamber at -40℃ for 48 hours.

[0057] Step 7: Take out the freeze-dried reconstituted jujube products, package them with light-proof and oxygen-proof aluminum foil, vacuum seal them, and store them in a cool and dry place.

[0058] Example 2

[0059] A method for preparing freeze-dried recombinant jujube products includes:

[0060] Step 1: Select plump, intact red dates, chickpeas, and quinoa that are free from insect damage. Add water to the red dates and chickpeas at a ratio of 1:4 (w / w) and cook at 100℃ for 25 minutes. Add water to the quinoa at a ratio of 1:4 (w / w) and cook at 100℃ for 10 minutes to allow them to absorb water, expand, soften, and cook. Then drain the water.

[0061] Step 2: Combine the softened and cooked chickpeas, quinoa, and red dates. The ratio of chickpeas to quinoa is fixed at 1:1 (w / w). Based on the total weight of chickpeas, quinoa, and red dates, add chickpeas and quinoa at a total of 25% (w / w) to the red dates. Then add water at a material-to-liquid ratio of 1:1.5 (w / w) and blend in a high-speed blender for 3 minutes to obtain a mixed pulp of red dates, chickpeas, and quinoa.

[0062] Step 3: Treat the above mixed slurry at 85℃ for 10 minutes to perform pasteurization.

[0063] Step 4: Inoculate the sterilized mixed slurry with yeast starter at an inoculum rate of 0.02% (v / v) and ferment at 30°C for 6 hours. The initial bacterial concentration of the starter is 10. 9 ~10 10 CFU / mL. After fermentation, the yeast was sterilized at 85℃ for 10 min to terminate the fermentation.

[0064] Step 5: Inoculate the sterilized mixed slurry with lactic acid bacteria starter at an inoculum rate of 3% (v / v) and ferment at 37°C for 12 hours. The starter consists of Streptococcus thermophilus, Lactobacillus plantarum, Lactobacillus rhamnosus, Pediococcus pentosus, and Leuconostoc mesenteroides in a ratio of 1:2:1:1:1, with an initial bacterial concentration of 10 μL for each lactic acid bacteria. 7 ~10 8 CFU / mL.

[0065] Step 6: Pour the fermented red dates, chickpeas and quinoa paste into a mold, pre-freeze at -80℃ for 24 hours, and then place it in a vacuum freeze-drying chamber at -40℃ for 48 hours.

[0066] Step 7: Take out the freeze-dried reconstituted jujube products, package them with light-proof and oxygen-proof aluminum foil, vacuum seal them, and store them in a cool and dry place.

[0067] Example 3

[0068] A method for preparing freeze-dried recombinant jujube products includes:

[0069] Step 1: Select plump, intact red dates, chickpeas, and quinoa that are free from insect damage. Add water to the red dates and chickpeas at a ratio of 1:4 (w / w) and cook at 100℃ for 25 minutes. Add water to the quinoa at a ratio of 1:4 (w / w) and cook at 100℃ for 10 minutes to allow them to absorb water, expand, soften, and cook. Then drain the water.

[0070] Step 2: Combine the softened and cooked chickpeas, quinoa, and red dates. The ratio of chickpeas to quinoa is fixed at 1:1 (w / w). Based on the total weight of chickpeas, quinoa, and red dates, add chickpeas and quinoa at a total of 30% (w / w) to the red dates. Then add water at a material-to-liquid ratio of 1:1.5 (w / w) and blend in a high-speed blender for 3 minutes to obtain a mixed pulp of red dates, chickpeas, and quinoa.

[0071] Step 3: Treat the above mixed slurry at 85℃ for 10 minutes to perform pasteurization.

[0072] Step 4: Inoculate the sterilized mixed slurry with yeast starter at an inoculum rate of 0.02% (v / v) and ferment at 30°C for 6 hours. The initial bacterial concentration of the starter is 10. 9 ~10 10 CFU / mL. After fermentation, the yeast was sterilized at 85℃ for 10 min to terminate the fermentation.

[0073] Step 5: Inoculate the sterilized mixed slurry with lactic acid bacteria starter at an inoculum rate of 3% (v / v) and ferment at 37°C for 12 hours. The starter consists of Streptococcus thermophilus, Lactobacillus plantarum, Lactobacillus rhamnosus, Pediococcus pentosus, and Leuconostoc mesenteroides in a ratio of 1:2:1:1:1, with an initial bacterial concentration of 10 μL for each lactic acid bacteria. 7 ~10 8 CFU / mL.

[0074] Step 6: Pour the fermented red dates, chickpeas and quinoa paste into a mold, pre-freeze at -80℃ for 24 hours, and then place it in a vacuum freeze-drying chamber at -40℃ for 48 hours.

[0075] Step 7: Take out the freeze-dried reconstituted jujube products, package them with light-proof and oxygen-proof aluminum foil, vacuum seal them, and store them in a cool and dry place.

[0076] Example 4

[0077] A method for preparing freeze-dried recombinant jujube products includes:

[0078] Step 1: Select plump, intact red dates, chickpeas, and quinoa that are free from insect damage. Add water to the red dates and chickpeas at a ratio of 1:4 (w / w) and cook at 100℃ for 25 minutes. Add water to the quinoa at a ratio of 1:4 (w / w) and cook at 100℃ for 10 minutes to allow them to absorb water, expand, soften, and cook. Then drain the water.

[0079] Step 2: Combine the softened and cooked chickpeas, quinoa, and red dates. The ratio of chickpeas to quinoa is fixed at 1:1 (w / w). Based on the total weight of chickpeas, quinoa, and red dates, add chickpeas and quinoa at a total of 35% (w / w) to the red dates. Then add water at a material-to-liquid ratio of 1:1.5 (w / w) and blend in a high-speed blender for 3 minutes to obtain a mixed pulp of red dates, chickpeas, and quinoa.

[0080] Step 3: Treat the above mixed slurry at 85℃ for 10 minutes to perform pasteurization.

[0081] Step 4: Inoculate the sterilized mixed slurry with yeast starter at an inoculum rate of 0.02% (v / v) and ferment at 30°C for 6 hours. The initial bacterial concentration of the starter is 10. 9 ~10 10 CFU / mL. After fermentation, the yeast was sterilized at 85℃ for 10 min to terminate the fermentation.

[0082] Step 5: Inoculate the sterilized mixed slurry with lactic acid bacteria starter at an inoculum rate of 3% (v / v) and ferment at 37°C for 12 hours. The starter consists of Streptococcus thermophilus, Lactobacillus plantarum, Lactobacillus rhamnosus, Pediococcus pentosus, and Leuconostoc mesenteroides in a ratio of 1:2:1:1:1, with an initial bacterial concentration of 10 μL for each lactic acid bacteria. 7 ~10 8 CFU / mL.

[0083] Step 6: Pour the fermented red dates, chickpeas and quinoa paste into a mold, pre-freeze at -80℃ for 24 hours, and then place it in a vacuum freeze-drying chamber at -40℃ for 48 hours.

[0084] Step 7: Take out the freeze-dried reconstituted jujube products, package them with light-proof and oxygen-proof aluminum foil, vacuum seal them, and store them in a cool and dry place.

[0085] Example 5

[0086] A method for preparing freeze-dried recombinant jujube products includes:

[0087] Step 1: Select plump, intact red dates, chickpeas, and quinoa that are free from insect damage. Add water to the red dates and chickpeas at a ratio of 1:4 (w / w) and cook at 100℃ for 25 minutes. Add water to the quinoa at a ratio of 1:4 (w / w) and cook at 100℃ for 10 minutes to allow them to absorb water, expand, soften, and cook. Then drain the water.

[0088] Step 2: Combine the softened and cooked chickpeas, quinoa, and red dates. The ratio of chickpeas to quinoa is fixed at 1:1 (w / w). Based on the total weight of chickpeas, quinoa, and red dates, add chickpeas and quinoa at a total of 40% (w / w) to the red dates. Then add water at a material-to-liquid ratio of 1:1.5 (w / w) and blend in a high-speed blender for 3 minutes to obtain a mixed pulp of red dates, chickpeas, and quinoa.

[0089] Step 3: Treat the above mixed slurry at 85℃ for 10 minutes to perform pasteurization.

[0090] Step 4: Inoculate the sterilized mixed slurry with yeast starter at an inoculum rate of 0.02% (v / v) and ferment at 30°C for 6 hours. The initial bacterial concentration of the starter is 10. 9 ~10 10 CFU / mL. After fermentation, the yeast was sterilized at 85℃ for 10 min to terminate the fermentation.

[0091] Step 5: Inoculate the sterilized mixed slurry with lactic acid bacteria starter at an inoculum rate of 3% (v / v) and ferment at 37°C for 12 hours. The starter consists of Streptococcus thermophilus, Lactobacillus plantarum, Lactobacillus rhamnosus, Pediococcus pentosus, and Leuconostoc mesenteroides in a ratio of 1:2:1:1:1, with an initial bacterial concentration of 10 μL for each lactic acid bacteria. 7 ~10 8 CFU / mL.

[0092] Step 6: Pour the fermented red dates, chickpeas and quinoa paste into a mold, pre-freeze at -80℃ for 24 hours, and then place it in a vacuum freeze-drying chamber at -40℃ for 48 hours.

[0093] Step 7: Take out the freeze-dried reconstituted jujube products, package them with light-proof and oxygen-proof aluminum foil, vacuum seal them, and store them in a cool and dry place.

[0094] Example 6

[0095] A method for preparing freeze-dried recombinant jujube products includes:

[0096] Step 1: Select plump, intact red dates, chickpeas, and quinoa that are free from insect damage. Add water to the red dates and chickpeas at a ratio of 1:4 (w / w) and cook at 100℃ for 25 minutes. Add water to the quinoa at a ratio of 1:4 (w / w) and cook at 100℃ for 10 minutes to allow them to absorb water, expand, soften, and cook. Then drain the water.

[0097] Step 2: Combine the softened and cooked chickpeas, quinoa, and red dates. The ratio of chickpeas to quinoa is fixed at 1:2 (w / w). Based on the total weight of chickpeas, quinoa, and red dates, add chickpeas and quinoa at a total of 30% (w / w) to the red dates. Then add water at a material-to-liquid ratio of 1:1.5 (w / w) and blend in a high-speed blender for 3 minutes to obtain a mixed pulp of red dates, chickpeas, and quinoa.

[0098] Step 3: Treat the above mixed slurry at 85℃ for 10 minutes to perform pasteurization.

[0099] Step 4: Inoculate the sterilized mixed slurry with yeast starter at an inoculum rate of 0.02% (v / v) and ferment at 30°C for 6 hours. The initial bacterial concentration of the starter is 10. 9 ~10 10 CFU / mL. After fermentation, the yeast was sterilized at 85℃ for 10 min to terminate the fermentation.

[0100] Step 5: Inoculate the sterilized mixed slurry with lactic acid bacteria starter at an inoculum rate of 3% (v / v) and ferment at 37°C for 12 hours. The starter consists of Streptococcus thermophilus, Lactobacillus plantarum, Lactobacillus rhamnosus, Pediococcus pentosus, and Leuconostoc mesenteroides in a ratio of 1:2:1:1:1, with an initial bacterial concentration of 10 μL for each lactic acid bacteria. 7 ~10 8 CFU / mL.

[0101] Step 6: Pour the fermented red dates, chickpeas and quinoa paste into a mold, pre-freeze at -80℃ for 24 hours, and then place it in a vacuum freeze-drying chamber at -40℃ for 48 hours.

[0102] Step 7: Take out the freeze-dried reconstituted jujube products, package them with light-proof and oxygen-proof aluminum foil, vacuum seal them, and store them in a cool and dry place.

[0103] Example 7

[0104] A method for preparing freeze-dried recombinant jujube products includes:

[0105] Step 1: Select plump, intact red dates, chickpeas, and quinoa that are free from insect damage. Add water to the red dates and chickpeas at a ratio of 1:4 (w / w) and cook at 100℃ for 25 minutes. Add water to the quinoa at a ratio of 1:4 (w / w) and cook at 100℃ for 10 minutes to allow them to absorb water, expand, soften, and cook. Then drain the water.

[0106] Step 2: Combine the softened and cooked chickpeas, quinoa, and red dates. The ratio of chickpeas to quinoa is fixed at 2:1 (w / w). Based on the total weight of chickpeas, quinoa, and red dates, add chickpeas and quinoa at a total of 30% (w / w) to the red dates. Then add water at a material-to-liquid ratio of 1:1.5 (w / w) and blend in a high-speed blender for 3 minutes to obtain a mixed pulp of red dates, chickpeas, and quinoa.

[0107] Step 3: Treat the above mixed slurry at 85℃ for 10 minutes to perform pasteurization.

[0108] Step 4: Inoculate the sterilized mixed slurry with yeast starter at an inoculum rate of 0.02% (v / v) and ferment at 30°C for 6 hours. The initial bacterial concentration of the starter is 10. 9 ~10 10 CFU / mL. After fermentation, the yeast was sterilized at 85℃ for 10 min to terminate the fermentation.

[0109] Step 5: Inoculate the sterilized mixed slurry with lactic acid bacteria starter at an inoculum rate of 3% (v / v) and ferment at 37°C for 12 hours. The starter consists of Streptococcus thermophilus, Lactobacillus plantarum, Lactobacillus rhamnosus, Pediococcus pentosus, and Leuconostoc mesenteroides in a ratio of 1:2:1:1:1, with an initial bacterial concentration of 10 μL for each lactic acid bacteria. 7 ~10 8 CFU / mL.

[0110] Step 6: Pour the fermented red dates, chickpeas and quinoa paste into a mold, pre-freeze at -80℃ for 24 hours, and then place it in a vacuum freeze-drying chamber at -40℃ for 48 hours.

[0111] Step 7: Take out the freeze-dried reconstituted jujube products, package them with light-proof and oxygen-proof aluminum foil, vacuum seal them, and store them in a cool and dry place.

[0112] Example 8

[0113] A method for preparing freeze-dried recombinant jujube products includes:

[0114] Step 1: Select plump, intact red dates, chickpeas, and quinoa that are free from insect damage. Add water to the red dates and chickpeas at a ratio of 1:4 (w / w) and cook at 100℃ for 25 minutes. Add water to the quinoa at a ratio of 1:4 (w / w) and cook at 100℃ for 10 minutes to allow them to absorb water, expand, soften, and cook. Then drain the water.

[0115] Step 2: Combine the softened and cooked chickpeas, quinoa, and red dates. The ratio of chickpeas to quinoa is fixed at 1:3 (w / w). Based on the total weight of chickpeas, quinoa, and red dates, add chickpeas and quinoa at a total of 30% (w / w) to the red dates. Then add water at a material-to-liquid ratio of 1:1.5 (w / w) and blend in a high-speed blender for 3 minutes to obtain a mixed pulp of red dates, chickpeas, and quinoa.

[0116] Step 3: Treat the above mixed slurry at 85℃ for 10 minutes to perform pasteurization.

[0117] Step 4: Inoculate the sterilized mixed slurry with yeast starter at an inoculum rate of 0.02% (v / v) and ferment at 30°C for 6 hours. The initial bacterial concentration of the starter is 10. 9 ~10 10 CFU / mL. After fermentation, the yeast was sterilized at 85℃ for 10 min to terminate the fermentation.

[0118] Step 5: Inoculate the sterilized mixed slurry with lactic acid bacteria starter at an inoculum rate of 3% (v / v) and ferment at 37°C for 12 hours. The starter consists of Streptococcus thermophilus, Lactobacillus plantarum, Lactobacillus rhamnosus, Pediococcus pentosus, and Leuconostoc mesenteroides in a ratio of 1:2:1:1:1, with an initial bacterial concentration of 10 μL for each lactic acid bacteria. 7 ~10 8 CFU / mL.

[0119] Step 6: Pour the fermented red dates, chickpeas and quinoa paste into a mold, pre-freeze at -80℃ for 24 hours, and then place it in a vacuum freeze-drying chamber at -40℃ for 48 hours.

[0120] Step 7: Take out the freeze-dried reconstituted jujube products, package them with light-proof and oxygen-proof aluminum foil, vacuum seal them, and store them in a cool and dry place.

[0121] Example 9

[0122] A method for preparing freeze-dried recombinant jujube products includes:

[0123] Step 1: Select plump, intact red dates, chickpeas, and quinoa that are free from insect damage. Add water to the red dates and chickpeas at a ratio of 1:4 (w / w) and cook at 100℃ for 25 minutes. Add water to the quinoa at a ratio of 1:4 (w / w) and cook at 100℃ for 10 minutes to allow them to absorb water, expand, soften, and cook. Then drain the water.

[0124] Step 2: Combine the softened and cooked chickpeas, quinoa, and red dates. The ratio of chickpeas to quinoa is fixed at 3:1 (w / w). Based on the total weight of chickpeas, quinoa, and red dates, add chickpeas and quinoa at a total of 30% (w / w) to the red dates. Then add water at a material-to-liquid ratio of 1:1.5 (w / w) and blend in a high-speed blender for 3 minutes to obtain a mixed pulp of red dates, chickpeas, and quinoa.

[0125] Step 3: Treat the above mixed slurry at 85℃ for 10 minutes to perform pasteurization.

[0126] Step 4: Inoculate the sterilized mixed slurry with yeast starter at an inoculum rate of 0.02% (v / v) and ferment at 30°C for 6 hours. The initial bacterial concentration of the starter is 10. 9 ~10 10 CFU / mL. After fermentation, the yeast was sterilized at 85℃ for 10 min to terminate the fermentation.

[0127] Step 5: Inoculate the sterilized mixed slurry with lactic acid bacteria starter at an inoculum rate of 3% (v / v) and ferment at 37°C for 12 hours. The starter consists of Streptococcus thermophilus, Lactobacillus plantarum, Lactobacillus rhamnosus, Pediococcus pentosus, and Leuconostoc mesenteroides in a ratio of 1:2:1:1:1, with an initial bacterial concentration of 10 μL for each lactic acid bacteria. 7 ~10 8 CFU / mL.

[0128] Step 6: Pour the fermented red dates, chickpeas and quinoa paste into a mold, pre-freeze at -80℃ for 24 hours, and then place it in a vacuum freeze-drying chamber at -40℃ for 48 hours.

[0129] Step 7: Take out the freeze-dried reconstituted jujube products, package them with light-proof and oxygen-proof aluminum foil, vacuum seal them, and store them in a cool and dry place.

[0130] Example 10

[0131] A method for preparing freeze-dried recombinant jujube products includes:

[0132] Step 1: Select plump, intact red dates, chickpeas, and quinoa that are free from insect damage. Add water to the red dates and chickpeas at a ratio of 1:4 (w / w) and cook at 100℃ for 25 minutes. Add water to the quinoa at a ratio of 1:4 (w / w) and cook at 100℃ for 10 minutes to allow them to absorb water, expand, soften, and cook. Then drain the water.

[0133] Step 2: Combine the softened and cooked chickpeas, quinoa, and red dates. The ratio of chickpeas to quinoa is fixed at 1:2 (w / w). Based on the total weight of chickpeas, quinoa, and red dates, add chickpeas and quinoa at a total addition amount of 25% (w / w) to the red dates. Then add water at a material-to-liquid ratio of 1:1.5 (w / w) and blend in a high-speed blender for 3 minutes to obtain a mixed pulp of red dates, chickpeas, and quinoa.

[0134] Step 3: Treat the above mixed slurry at 85℃ for 10 minutes to perform pasteurization.

[0135] Step 4: Inoculate the sterilized mixed slurry with yeast starter at an inoculum rate of 0.02% (v / v) and ferment at 30°C for 6 hours. The initial bacterial concentration of the starter is 10. 9 ~10 10 CFU / mL. After fermentation, the yeast was sterilized at 85℃ for 10 min to terminate the fermentation.

[0136] Step 5: Inoculate the sterilized mixed slurry with lactic acid bacteria starter at an inoculum rate of 3% (v / v) and ferment at 37°C for 12 hours. The starter consists of Streptococcus thermophilus, Lactobacillus plantarum, Lactobacillus rhamnosus, Pediococcus pentosus, and Leuconostoc mesenteroides in a ratio of 1:2:1:1:1, with an initial bacterial concentration of 10 μL for each lactic acid bacteria. 7 ~10 8 CFU / mL.

[0137] Step 6: Pour the fermented red dates, chickpeas and quinoa paste into a mold, pre-freeze at -80℃ for 24 hours, and then place it in a vacuum freeze-drying chamber at -40℃ for 48 hours.

[0138] Step 7: Take out the freeze-dried reconstituted jujube products, package them with light-proof and oxygen-proof aluminum foil, vacuum seal them, and store them in a cool and dry place.

[0139] Example 11

[0140] A method for preparing freeze-dried recombinant jujube products includes:

[0141] Step 1: Select plump, intact red dates, chickpeas, and quinoa that are free from insect damage. Add water to the red dates and chickpeas at a ratio of 1:4 (w / w) and cook at 100℃ for 25 minutes. Add water to the quinoa at a ratio of 1:4 (w / w) and cook at 100℃ for 10 minutes to allow them to absorb water, expand, soften, and cook. Then drain the water.

[0142] Step 2: Combine the softened and cooked chickpeas, quinoa, and red dates. The ratio of chickpeas to quinoa is fixed at 2:1 (w / w). Based on the total weight of chickpeas, quinoa, and red dates, add chickpeas and quinoa at a total of 25% (w / w) to the red dates. Then add water at a material-to-liquid ratio of 1:1.5 (w / w) and blend in a high-speed blender for 3 minutes to obtain a mixed pulp of red dates, chickpeas, and quinoa.

[0143] Step 3: Treat the above mixed slurry at 85℃ for 10 minutes to perform pasteurization.

[0144] Step 4: Inoculate the sterilized mixed slurry with yeast starter at an inoculum rate of 0.02% (v / v) and ferment at 30°C for 6 hours. The initial bacterial concentration of the starter is 10. 9 ~10 10 CFU / mL. After fermentation, the yeast was sterilized at 85℃ for 10 min to terminate the fermentation.

[0145] Step 5: Inoculate the sterilized mixed slurry with lactic acid bacteria starter at an inoculum rate of 3% (v / v) and ferment at 37°C for 12 hours. The starter consists of Streptococcus thermophilus, Lactobacillus plantarum, Lactobacillus rhamnosus, Pediococcus pentosus, and Leuconostoc mesenteroides in a ratio of 1:2:1:1:1, with an initial bacterial concentration of 10 μL for each lactic acid bacteria. 7 ~10 8 CFU / mL.

[0146] Step 6: Pour the fermented red dates, chickpeas and quinoa paste into a mold, pre-freeze at -80℃ for 24 hours, and then place it in a vacuum freeze-drying chamber at -40℃ for 48 hours.

[0147] Step 7: Take out the freeze-dried reconstituted jujube products, package them with light-proof and oxygen-proof aluminum foil, vacuum seal them, and store them in a cool and dry place.

[0148] Example 12

[0149] A method for preparing freeze-dried recombinant jujube products includes:

[0150] Step 1: Select plump, intact red dates, chickpeas, and quinoa that are free from insect damage. Add water to the red dates and chickpeas at a ratio of 1:4 (w / w) and cook at 100℃ for 25 minutes. Add water to the quinoa at a ratio of 1:4 (w / w) and cook at 100℃ for 10 minutes to allow them to absorb water, expand, soften, and cook. Then drain the water.

[0151] Step 2: Combine the softened and cooked chickpeas, quinoa, and red dates. The ratio of chickpeas to quinoa is fixed at 1:2 (w / w). Based on the total weight of chickpeas, quinoa, and red dates, add chickpeas and quinoa at a total addition amount of 35% (w / w) to the red dates. Then add water at a material-to-liquid ratio of 1:1.5 (w / w) and blend in a high-speed blender for 3 minutes to obtain a mixed pulp of red dates, chickpeas, and quinoa.

[0152] Step 3: Treat the above mixed slurry at 85℃ for 10 minutes to perform pasteurization.

[0153] Step 4: Inoculate the sterilized mixed slurry with yeast starter at an inoculum rate of 0.02% (v / v) and ferment at 30°C for 6 hours. The initial bacterial concentration of the starter is 10. 9 ~10 10 CFU / mL. After fermentation, the yeast was sterilized at 85℃ for 10 min to terminate the fermentation.

[0154] Step 5: Inoculate the sterilized mixed slurry with lactic acid bacteria starter at an inoculum rate of 3% (v / v) and ferment at 37°C for 12 hours. The starter consists of Streptococcus thermophilus, Lactobacillus plantarum, Lactobacillus rhamnosus, Pediococcus pentosus, and Leuconostoc mesenteroides in a ratio of 1:2:1:1:1, with an initial bacterial concentration of 10 μL for each lactic acid bacteria. 7 ~10 8 CFU / mL.

[0155] Step 6: Pour the fermented red dates, chickpeas and quinoa paste into a mold, pre-freeze at -80℃ for 24 hours, and then place it in a vacuum freeze-drying chamber at -40℃ for 48 hours.

[0156] Step 7: Take out the freeze-dried reconstituted jujube products, package them with light-proof and oxygen-proof aluminum foil, vacuum seal them, and store them in a cool and dry place.

[0157] Example 13

[0158] A method for preparing freeze-dried recombinant jujube products includes:

[0159] Step 1: Select plump, intact red dates, chickpeas, and quinoa that are free from insect damage. Add water to the red dates and chickpeas at a ratio of 1:4 (w / w) and cook at 100℃ for 25 minutes. Add water to the quinoa at a ratio of 1:4 (w / w) and cook at 100℃ for 10 minutes to allow them to absorb water, expand, soften, and cook. Then drain the water.

[0160] Step 2: Combine the softened and cooked chickpeas, quinoa, and red dates. The ratio of chickpeas to quinoa is fixed at 2:1 (w / w). Based on the total weight of chickpeas, quinoa, and red dates, add chickpeas and quinoa at a total addition amount of 35% (w / w) to the red dates. Then add water at a material-to-liquid ratio of 1:1.5 (w / w) and blend in a high-speed blender for 3 minutes to obtain a mixed pulp of red dates, chickpeas, and quinoa.

[0161] Step 3: Treat the above mixed slurry at 85℃ for 10 minutes to perform pasteurization.

[0162] Step 4: Inoculate the sterilized mixed slurry with yeast starter at an inoculum rate of 0.02% (v / v) and ferment at 30°C for 6 hours. The initial bacterial concentration of the starter is 10. 9 ~10 10 CFU / mL. After fermentation, the yeast was sterilized at 85℃ for 10 min to terminate the fermentation.

[0163] Step 5: Inoculate the sterilized mixed slurry with lactic acid bacteria starter at an inoculum rate of 3% (v / v) and ferment at 37°C for 12 hours. The starter consists of Streptococcus thermophilus, Lactobacillus plantarum, Lactobacillus rhamnosus, Pediococcus pentosus, and Leuconostoc mesenteroides in a ratio of 1:2:1:1:1, with an initial bacterial concentration of 10 μL for each lactic acid bacteria. 7 ~10 8 CFU / mL.

[0164] Step 6: Pour the fermented red dates, chickpeas and quinoa paste into a mold, pre-freeze at -80℃ for 24 hours, and then place it in a vacuum freeze-drying chamber at -40℃ for 48 hours.

[0165] Step 7: Take out the freeze-dried reconstituted jujube products, package them with light-proof and oxygen-proof aluminum foil, vacuum seal them, and store them in a cool and dry place.

[0166] Comparative Example 1

[0167] The sample preparation method is the same as in Example 13, except that only red dates are used in steps one and two, without adding chickpeas and quinoa. The sample obtained by this method is called freeze-dried recombinant pure red date product.

[0168] Comparative Example 2

[0169] The sample preparation method is the same as in Example 13, except that: only red dates are used in step one; and soy protein isolate is used instead of chickpeas and quinoa in step two.

[0170] By measuring the protein content in jujube pulp and a mixture of jujube, chickpea, and quinoa, it was found that the added protein from chickpeas and quinoa was 3.8 mg / g. Therefore, this content was used as the amount of soy protein isolate to be added. Step two involved adding water to jujubes at a 1:1.5 material-to-liquid ratio (w / w), then adding 3.8 mg / g of soy protein isolate, and finally blending in a high-speed blender for 3 minutes to obtain protein-added jujube pulp. The final freeze-dried product is called protein-added freeze-dried recombinant jujube product.

[0171] Comparative Example 3

[0172] The sample preparation method is the same as in Example 13, except that: only red dates are used in step one; and corn starch is used instead of chickpeas and quinoa in step two.

[0173] By measuring the starch content of jujube pulp and a mixture of jujube, chickpea, and quinoa pulp, it was found that the added starch from chickpeas and quinoa was 20.92 mg / g. Therefore, this content was used as the amount of corn starch to be added. Step two involved adding water to jujubes at a material-to-liquid ratio of 1:1.5 (w / w), then adding 20.92 mg / g of corn starch, and finally blending the mixture in a high-speed blender for 3 minutes to obtain jujube pulp with added starch. The final freeze-dried product is called freeze-dried reconstituted jujube product with added starch.

[0174] Comparative Example 4

[0175] The sample preparation method is the same as in Example 13, except that: only red dates are used in step one; and corn starch and soy protein isolate are used instead of chickpeas and quinoa in step two.

[0176] Based on Comparative Examples 2 and 3, the added protein and starch content from chickpeas and quinoa were 3.8 mg / g and 20.92 mg / g, respectively. Therefore, the recommended addition amount of soy protein isolate was determined to be 3.8 mg / g, and the recommended addition amount of corn starch was determined to be 20.92 mg / g. Step two involved adding water to red dates at a material-to-liquid ratio of 1:1.5 (w / w), then adding 3.8 mg / g of soy protein isolate and 20.92 mg / g of corn starch. The mixture was then blended in a high-speed blender for 3 minutes to obtain a red date paste with added protein and starch. The final freeze-dried product is called a freeze-dried recombinant red date product with added protein and starch.

[0177] Comparative Example 5

[0178] The sample preparation method is the same as in Example 13, except that steps four and five (i.e., without yeast and lactic acid bacteria fermentation) are not performed. The resulting sample is called freeze-dried recombinant jujube product with added chickpeas and quinoa without fermentation.

[0179] Comparative Example 6

[0180] Add water to red dates at a ratio of 1:4 (w / w) and boil at 100℃ for 25 minutes to allow them to absorb water, swell, soften, and mature. Then drain the water. Add water to the softened and matured red dates at a ratio of 1:1.5 (w / w) and blend in a high-speed blender for 3 minutes. The resulting sample is called red date pulp.

[0181] Test case

[0182] 1. Effect of chickpea and quinoa addition on the hygroscopicity of freeze-dried recombinant jujube products

[0183] The hygroscopicity of the freeze-dried recombinant jujube products prepared in Examples 1-5 was investigated to evaluate the effect of the addition of chickpeas and quinoa on the hygroscopicity of the freeze-dried recombinant jujube products.

[0184] The testing method is as follows: Accurately weigh 1.0 g of each of the freeze-dried samples from Examples 1 to 5 and place them in a pre-weighed petri dish. Place the petri dish containing the sample in the upper layer of a sealed desiccator, with a saturated sodium chloride solution in the lower layer. Then place the desiccator in a 25°C constant temperature oven. Weigh the petri dish every 24 hours until the weight change of the petri dish is less than 0.001 g in two consecutive tests. This indicates that the sample has reached hygroscopic equilibrium in the container. The hygroscopic rate of the freeze-dried sample can then be calculated using the following formula:

[0185]

[0186] In the formula, A is the moisture absorption rate of the product (%); m1 is the total mass of the product and the petri dish after moisture absorption (g); m2 is the total mass of the product and the petri dish before moisture absorption (g); and m0 is the mass of the product before moisture absorption (g).

[0187] The results are as follows Figure 1 As shown.

[0188] The results showed that the moisture absorption rate of the freeze-dried recombinant jujube product significantly decreased with increasing chickpea and quinoa content. Jujubes have high hygroscopicity due to their high sugar content; by combining them with chickpeas and quinoa, which have low sugar content and are rich in biomolecules, the sugar content of the product can be reduced, thus decreasing its hygroscopicity. Furthermore, the biomolecules (such as proteins and starches) abundant in chickpeas and quinoa provide a stable framework for the freeze-dried product, helping to slow the migration and aggregation of small sugar molecules to the product surface during freeze-drying, thereby reducing the product's hygroscopicity. It is worth noting that excessive amounts of chickpeas and quinoa weaken the typical jujube flavor characteristics of the product; simultaneously, the excessively viscous slurry hinders the diffusion and drying of moisture. Therefore, the optimal addition amount of chickpeas and quinoa is 25%–35%.

[0189] 2. Effect of the ratio of chickpeas to quinoa on the hygroscopicity of freeze-dried recombinant jujube products

[0190] The hygroscopicity of the freeze-dried recombinant jujube products prepared in Examples 3 and 6-9 was investigated to evaluate the effect of the ratio of chickpeas to quinoa on the hygroscopicity of the freeze-dried recombinant jujube products.

[0191] Hygroscopicity test method: Same as test example 1, the hygroscopicity of examples 3, 6 to 9 was measured.

[0192] The results are as follows Figure 2 As shown.

[0193] The results showed that the ratio of chickpeas to quinoa affects the product's hygroscopicity. A higher proportion of quinoa resulted in higher hygroscopicity, while a higher proportion of chickpeas resulted in lower hygroscopicity. Notably, increasing the proportion of chickpeas introduced more unpleasant beany flavors. Therefore, the optimal ratio of chickpeas to quinoa is 1:2 to 2:1.

[0194] 3. Optimize the addition amount and ratio of chickpeas and quinoa based on orthogonal experiments.

[0195] A two-factor, three-level orthogonal experiment was designed to investigate the effects of chickpea and quinoa additions on the hygroscopicity and sensory quality of freeze-dried recombinant jujube products. Specifically, Examples 2, 3, 4, 6, 7, 10, 11, 12, and 13 were conducted.

[0196] 3.1 Hygroscopicity test

[0197] Hygroscopicity test method: same as in test example 1.

[0198] The results are as follows Figure 3 As shown.

[0199] The results showed that as the amount of chickpeas and quinoa added increased and the proportion of chickpeas increased, the moisture absorption rate of the product decreased. Among them, Example 13 had the lowest moisture absorption rate, that is, the amount of chickpeas and quinoa added was 35%, and the mass ratio of chickpeas to quinoa was 2:1.

[0200] 3.2 Sensory quality evaluation

[0201] Sensory evaluation was used to evaluate the sensory quality of nine freeze-dried recombinant jujube products from Examples 2, 3, 4, 6, 7, 10, 11, 12, and 13. The sensory evaluation team consisted of 10 professionals (5 men and 5 women) who had received long-term sensory training. They evaluated the color, texture, aroma, taste, and overall likability of the products. The sensory quality of the products was scored using a 10-point scale, with higher scores indicating better quality.

[0202] The results are as follows Figure 4 As shown.

[0203] The results showed that with the increase of chickpea and quinoa addition, the sensory quality of the freeze-dried recombinant jujube product improved, manifested in a change from brownish-red to brownish-yellow, uniform texture, characteristic jujube aroma, rich aroma without off-flavors, and a crisp texture with a balanced sweet and sour taste. The optimal addition amount of chickpea and quinoa was 35%, with a compound mass ratio of 1:1, 1:2, and 2:1, resulting in higher overall product appeal. Furthermore, considering the product's hygroscopicity, the preferred conditions of this invention are those described in Example 13, where the addition amount of chickpea and quinoa is 35%, and the compound mass ratio of chickpea to quinoa is 2:1. Under these conditions, the freeze-dried recombinant jujube product exhibits the lowest hygroscopicity and superior sensory quality.

[0204] 4. Quality Analysis of Freeze-Dried Recombinant Jujube Products

[0205] The samples used for quality analysis were those prepared by the preferred method of the present invention, namely the sample prepared in Example 13. They were compared with other methods commonly used to improve the textural stability of freeze-dried foods. The quality of freeze-dried recombinant jujube products of Example 13 and Comparative Examples 1-4 was analyzed to evaluate the effect of the method and product mentioned in the present invention on improving the textural stability of freeze-dried recombinant jujube products.

[0206] 4.1 Moisture absorption rate change curve

[0207] To record and compare the moisture absorption process of the above samples, the samples were placed in the inner chamber of a Comwell dish, and seven saturated salt solutions with different water activities were added [saturated lithium chloride solution with water activity of 0.113 (Aw = 0.113), saturated lithium chloride solution with water activity of 0.230...].

[0208] Saturated potassium acetate solution with a water activity of 0.230 (Aw = 0.432), saturated potassium carbonate solution with a water activity of 0.432 (Aw = 0.432), saturated sodium bromide solution with a water activity of 0.576 (Aw = 0.576), saturated sodium nitrite solution with a water activity of 0.610 (Aw = 0.610), saturated sodium chloride solution with a water activity of 0.753 (Aw = 0.753), and a water activity of 0.843...

[0209] A saturated potassium chloride solution with an Aw of 0.843 was placed in the outer chamber of seven Comwell dishes to create different relative humidity environments. The Comwell dishes were then placed in a 25°C incubator, and the weight change of the samples under specific temperature and humidity conditions was monitored. A moisture absorption rate curve was plotted, and the formula for calculating the sample moisture absorption rate is as follows:

[0210]

[0211] Where Xi is the moisture absorption rate (%) of the sample in the i-th hour; mi is the weight (g) of the sample and the plate in the i-th hour; ms is the weight (g) of the dried sample and the plate; and m0 is the weight (g) of the plate.

[0212] The results are as follows Figure 5 The color of each sample after 25 hours in an environment with progressively increasing relative humidity is shown.

[0213] The results showed that as the relative humidity increased (from Aw = 0.113 to Aw = 0.843), the color of the samples darkened after absorbing moisture. The freeze-dried recombinant jujube sample (Comparative Example 1) changed from pale yellow to brownish-red, showing significant deterioration in color quality. The addition of starch and protein slightly improved the color deterioration of the freeze-dried recombinant jujube product under different humidity conditions. Notably, the freeze-dried recombinant jujube product with added chickpeas and quinoa, preferred in this invention, showed the least color change after moisture absorption.

[0214] By monitoring the moisture absorption process of each sample under three relative humidity conditions [created by saturated sodium nitrite solution (Aw = 0.610), saturated sodium chloride solution (Aw = 0.753), and saturated potassium chloride solution (Aw = 0.843)], it was found that (corresponding to...) Figure 6 A, Figure 6 B and Figure 6C) As the storage time increased, the hygroscopicity of each sample first increased sharply and then stabilized. Furthermore, the lower the relative humidity of the environment, the lower the hygroscopic rate at which each sample reached hygroscopic stability. It is noteworthy that, compared to the freeze-dried recombinant pure jujube sample (Comparative Example 1), the freeze-dried sample with added chickpeas and quinoa (Example 13) showed the most significant effect in reducing hygroscopicity, followed by the freeze-dried sample with added protein and starch (Comparative Example 4), the freeze-dried sample with added starch (Comparative Example 3), and the freeze-dried sample with added protein (Comparative Example 2).

[0215] 4.2 Phase transition temperature

[0216] The eutectic point, eutectic melting point, and glass transition temperature of the sample were determined using a differential scanning calorimeter. 10 mg of sample was weighed and placed in an aluminum crucible, which was then sealed using a tablet press. The instrument scanning program was as follows: cooling from 30 °C to -50 °C at a rate of 10 °C / min, equilibrating for 10 min, and then heating to 100 °C at the same rate to determine the eutectic point, eutectic melting point, and glass transition temperature of the sample.

[0217] The eutectic point reflects the phase transition temperature of a material from a liquid to a solid state. Table 1 shows that the addition of protein, starch, chickpeas, and quinoa slightly lowers the eutectic point of the products, but the differences in eutectic points among the samples are not significant. The eutectic point reflects the melting temperature of a material during heating. Table 1 shows that the addition of protein, starch, chickpeas, and quinoa increases the eutectic point of the products, with the addition of chickpeas and quinoa having the most significant effect. The glass transition temperature is an important indicator of food stability, affecting the texture and shelf life of food. When the ambient temperature is higher than the glass transition temperature of the product, the product is prone to oxidation, structural collapse, and other quality deterioration, which is detrimental to product storage.

[0218] The results are shown in Table 1.

[0219] The results showed that, compared with the freeze-dried recombinant pure jujube sample, the addition of protein, starch, chickpeas and quinoa significantly increased the glass transition temperature of the product. Among them, the addition of chickpeas and quinoa, which are preferred in this invention, had the best effect. The macromolecules in quinoa and chickpeas can reduce the molecular migration rate inside the sample through bonding, thereby increasing the glass transition temperature of the product, which helps to improve the texture stability of the product and extend its shelf life.

[0220] Table 1 Phase transition temperatures of each sample

[0221]

[0222]

[0223] Note: Different lowercase letters in each column indicate significant differences between samples (p<0.05).

[0224] 4.3 Hardness and Brittleness

[0225] The hardness and brittleness of the samples were determined using a physical property analyzer.

[0226] The results are shown in Table 2.

[0227] The results showed that, compared with the freeze-dried recombinant jujube sample (Comparative Example 1), the addition of protein, starch, chickpeas, and quinoa reduced the hardness and brittleness of the freeze-dried recombinant jujube product. The sample with added chickpeas and quinoa exhibited the lowest hardness and brittleness, indicating that the preferred method of this invention effectively improves the textural properties of the freeze-dried recombinant jujube product. This is because the addition of macromolecules such as starch and protein helps to slow down the diffusion and aggregation of small molecules to the food surface during freeze-drying, avoiding the formation of a "hard shell" on the surface of the freeze-dried recombinant jujube product and significantly reducing its hardness. Furthermore, the added macromolecules can fill the original large pore structure of the freeze-dried recombinant jujube sample, providing structural support and transforming the high-brittle sample into a low-brittle sample with a uniform, dense small-pore structure. It is worth noting that the effective components for improving the textural quality of freeze-dried products using the preferred method of this invention are not limited to starch and protein; other potential effective components also exist.

[0228] Table 2 Hardness and brittleness values ​​of each sample

[0229]

[0230] Note: Different lowercase letters in each column indicate significant differences between samples (p<0.05).

[0231] 5. Effects of the addition of chickpeas and oats and fermentation pretreatment on the quality of freeze-dried recombinant jujube products

[0232] Liquid chromatography was used to evaluate the content of small molecule sugars (glucose, fructose and sucrose) and organic acids in Examples 13, 5 and 6, in order to explore the material basis of the influence of the addition of chickpeas and quinoa and fermentation pretreatment on the textural stability and sensory quality of freeze-dried recombinant jujube products.

[0233] The results are shown in Table 3.

[0234] The results showed that, compared with pure jujube pulp, the addition of chickpeas and quinoa reduced the content of hygroscopic small-molecule sugars such as fructose, glucose, and sucrose in the samples. Furthermore, fermentation by yeast and lactic acid bacteria further reduced the content of these small-molecule sugars, helping to decrease the product's hygroscopicity. In addition, compared with pure jujube pulp, the samples with added chickpeas and quinoa (unfermented) showed a decrease in lactic acid and acetic acid content. However, after fermentation by yeast and lactic acid bacteria, the preferred sample of this invention (i.e., the freeze-dried recombinant jujube product with added chickpeas and quinoa after fermentation) showed a significant increase in lactic acid and acetic acid content, resulting in a richer flavor with a balanced sweet and sour taste. Simultaneously, lactic acid and acetic acid further transformed into volatile flavor components, making the product's aroma more intense.

[0235] Table 3. Monosaccharide and organic acid content of each sample

[0236]

[0237] Note: Different lowercase letters in each line indicate significant differences between samples (p<0.05).

[0238] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples, without contradiction. Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for preparing freeze-dried recombinant jujube products, characterized in that, The raw materials for preparing the freeze-dried recombinant jujube product include: jujubes, chickpeas, and quinoa; the method includes: The raw materials are softened and cooked separately, then compounded to obtain a compound raw material; the compound raw material is crushed to obtain crushed compound raw material. The crushed compound raw materials are subjected to a first fermentation treatment with yeast to obtain a first fermented product; After the first fermentation product is subjected to a second sterilization treatment, it is then subjected to a second fermentation treatment with lactic acid bacteria to obtain a second fermentation product. The second fermentation product was freeze-dried to obtain the freeze-dried recombinant jujube product. Based on the total mass of the compound raw materials, the total content of the chickpeas and quinoa after softening and cooking is 25-35%; Based on the total mass of the compound raw materials, the mass ratio of the softened and cooked chickpeas to the quinoa is (1~2):(2~1).

2. The method according to claim 1, characterized in that, The final inoculum concentration of the yeast in the first fermentation treatment was 10. 9 ~10 10 CFU / mL, fermentation temperature 20~37℃, fermentation time 2~16 h; The yeast is Saccharomyces cerevisiae.

3. The method according to claim 2, characterized in that, The fermentation temperature is 28~30℃, and the fermentation time is 4~8 hours.

4. The method according to claim 1, characterized in that, In the second fermentation process, the final inoculation concentration of the lactic acid bacteria is 10. 7 ~10 8 CFU / mL, fermentation temperature 30~38℃, fermentation time 4~32 h; The lactic acid bacteria are selected from at least one of Streptococcus thermophilus, Lactobacillus plantarum, Lactobacillus rhamnosus, Pediococcus pentosus, and Leuconostoc mesenteroides.

5. The method according to claim 4, characterized in that, The fermentation temperature is 36~38℃, and the fermentation time is 8~16 h.

6. The method according to claim 1, characterized in that, The lactic acid bacteria consist of Streptococcus thermophilus, Lactobacillus plantarum, Lactobacillus rhamnosus, Pediococcus pentosus, and Leuconostoc mesenteroides. The microbial ratio of *Streptococcus thermophilus*: *Lactobacillus plantarum*: *Lactobacillus rhamnosus*, *Pediococcus pentosus* and *Leuconostoc mesenteroides* is 1:2:1:1:

1.

7. The method according to claim 1, characterized in that, The second sterilization treatment is performed at a temperature of 85°C for 10-30 minutes.

8. The method according to claim 1, characterized in that, The first fermentation process includes: after subjecting the crushed compound raw materials to a first sterilization treatment, inoculating them with the yeast and carrying out fermentation; wherein the temperature of the first sterilization treatment is 85°C and the time is 10~30 min.

9. The method according to claim 1, characterized in that, The freeze-drying process includes: pre-freezing and sublimation drying. The pre-freezing temperature is -80~-60℃ and the time is 12~36 h. The sublimation drying temperature is -45~-25℃ and the time is 24~72 h.

10. The method according to claim 9, characterized in that, The pre-freezing temperature is -80℃ and the time is 24 h; the sublimation drying temperature is -40℃ and the time is 48 h.

11. The method according to claim 1, characterized in that, The softening and cooking process includes: cooking the red dates, chickpeas, and quinoa separately, draining the water, and obtaining the softened and cooked red dates, chickpeas, and quinoa. The cooking time is 5-40 minutes, and the temperature is 100℃. The crushing process includes: adding water to the compound raw materials at a material-to-liquid ratio of 1:(1~4), and then grinding them in a blender for 3~5 minutes.

12. The method according to claim 11, characterized in that, The cooking time for the red dates or chickpeas is 15 to 40 minutes, and the amount of water added is 2 to 6 times the mass of the red dates or chickpeas. The cooking time for the quinoa is 5 to 25 minutes, and the amount of water added is 2 to 6 times the mass of the quinoa.

13. The method according to claim 12, characterized in that, The cooking time for the red dates or chickpeas is 20-30 minutes, and the amount of water added is 3-5 times the mass of the red dates or chickpeas. The quinoa is cooked for 5 to 15 minutes, and the amount of water added is 3 to 5 times the mass of the quinoa.

14. The method according to claim 1, characterized in that, The method further includes: vacuum packaging the freeze-dried recombinant jujube product; The vacuum packaging material is aluminum foil.

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