A dried soft kiwi fruit and a method for preparing the same

Abstract

The application provides a soft jujube-kiwi fruit preserve and a preparation method thereof, and belongs to the technical field of food processing. The preparation method of the soft jujube-kiwi fruit preserve comprises the following steps: after washing, polishing and peeling, and pretreatment, the soft jujube-kiwi is subjected to twice solid-state fermentation, and then subjected to circulation drying-softening, packaging, and the soft jujube-kiwi fruit preserve is obtained. The ripe fruit is softened and matured through the pretreatment, and the soluble components in the fruit are improved; the twice solid-state fermentation reduces the sour and astringent taste of the soft jujube-kiwi, and increases the content of flavonoids; the high-temperature heat circulation and air blowing drying treatment reduce the water content in the fruit, and improve the quality and taste of the fruit preserve; no food additive is added, the delicate taste of the soft jujube-kiwi is retained, the fruit preserve is more refreshing and not greasy, the taste is sour and sweet, the hardness is moderate, and the fruit preserve meets the requirements of the public for the quality and taste of the fruit preserve.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of food processing, and particularly relates to a preserved soft kiwi fruit and a preparation method thereof. BACKGROUND

[0002] Soft kiwi fruit (Actinidia arguta) is also known as strange berry, vegetable melon, round jujube, vine jujube and kiwi pear. The fruit is juicy, sour and sweet, and contains various proteins, amino acids, vitamins, minerals and other active ingredients such as volatile oils, triterpenes, flavonoids and polysaccharides. The soft kiwi fruit has the functions of anti-virus, anti-oxidation, anti-tumor, blood sugar reduction, obesity inhibition and immunity improvement, and is known as "healthy fruit".

[0003] The soft kiwi fruit is a small berry, which is prone to softening and rotting after being picked. If it cannot be sold in time, a large amount of resources will be lost and wasted. At present, there are relatively few products of the soft kiwi fruit, and the industrial development thereof is limited. Preserved fruits are a kind of leisure food and are very popular among people. The soft kiwi fruit is a rare raw material resource for preserved fruits due to its fruit structure characteristics. However, the soft kiwi fruit contains a large amount of VC and organic acids such as citric acid, and has a sour taste. A large amount of sucrose needs to be added in the process of making preserved fruits, which cannot meet the needs of the elderly, children and diabetic groups, and cannot cater to the consumption concept of modern people of low sugar and low fat. Therefore, it is urgent to invent a kind of soft kiwi fruit preserved fruit which can solve the problems of short storage period of fresh soft kiwi fruit, effectively retain nutritional ingredients and improve the sour taste. SUMMARY

[0004] In view of the deficiencies of the prior art, the purpose of the present application is to provide a kind of soft jujube kiwi fruit and a preparation method thereof. The soft jujube kiwi fruit prepared by the method of the present application has zero food additives, improves the sour taste of the soft jujube kiwi fruit itself and increases the content of flavonoids.

[0005] In order to achieve the above purpose, the present application provides the following technical scheme:

[0006] The present application provides a preparation method of soft jujube kiwi fruit, comprising: washing, polishing and peeling the soft jujube kiwi fruit, pretreating, twice solid state fermentation, then circulating drying-softening, packaging to obtain the soft jujube kiwi fruit; the twice solid state fermentation comprises: inoculating 2-5% mass of Saccharomyces cerevisiae liquid into the pretreated soft jujube kiwi fruit, fermenting at 25-30 DEG C for 3-5 days, then inoculating 3-8% mass of Pediococcus ethanolidurans liquid, fermenting at 32-37 DEG C for 7-15 days.

[0007] Preferably, the pretreatment comprises irradiation softening and microwave aging.

[0008] Preferably, the irradiation softening is treated by Co60, and the irradiation dose is 3.0-5.0 kGy.

[0009] Preferably, the microwave curing comprises: a first stage of 40-60℃ for 3-5 min, and a second stage of 80-100℃ for 1-2 min.

[0010] Preferably, the preservation number of the Saccharomyces cerevisiae is CGMCC No.2.1364, and the preservation number of the Pediococcus ethanolidurans is CGMCC No.29506.

[0011] Preferably, the cyclic drying-softening comprises: drying and roller-softening the soft-jujube after the solid-state fermentation, and repeating the drying and roller-softening for 3-5 times until the moisture content of the soft-jujube is 15-20%.

[0012] Preferably, the drying comprises instant air heating and low-temperature air blowing heating; the temperature of the instant air heating is 150-200℃, and the time is 5-8 min; the temperature of the low-temperature air blowing heating is 40-45℃, and the time is 3-4 h.

[0013] Preferably, the roller-softening comprises: roller-softening the dried soft-jujube, spraying Pediococcus ethanolidurans liquid, and softening at room temperature under dark conditions for 5-20 h.

[0014] Preferably, the roller-softening comprises: roller-softening the dried soft-jujube, spraying Pediococcus ethanolidurans liquid, and softening at room temperature under dark conditions for 5-20 h.

[0015] The application further provides the preserved soft-jujube prepared by the preparation method.

[0016] Compared with the prior art, the application has the following beneficial effects:

[0017] The application provides a preparation method of preserved soft-jujube, which comprises the following steps: washing, polishing and peeling soft-jujube, pretreating the soft-jujube, performing twice solid-state fermentation, and then performing cyclic drying-softening and packaging to obtain the preserved soft-jujube. The application can soften and cure the fruit through pretreatment, and increase the soluble ingredients in the fruit. The twice solid-state fermentation can reduce the sour taste of the soft-jujube, increase the content of flavonoids, ensure the nutritional value, and enrich the taste. The high-temperature heat cycle and air blowing drying can reduce the moisture content in the fruit, and improve the quality and taste of the preserved fruit. The application does not add any food additive, and retains the delicate taste of the soft-jujube. The preserved fruit is more refreshing and not greasy, has a sour and sweet taste, and has a moderate hardness. Compared with the traditional preserved fruit, the sugar content of the preserved fruit is lower, and the preserved fruit is suitable for more people, including people who pay attention to health, control blood sugar, and reduce sugar intake. The preserved fruit is more healthy and safe, and meets the requirements of the public for the quality and taste of the preserved fruit.

[0018] Microorganism preservation information

[0019] The Pediococcus ethanolidurans described in the present application, the biological material is X4-2, the recommended classification name is Pediococcus ethanolidurans, and the preservation number is CGMCC No.29506, the preservation date is January 2, 2024, and the preservation address is No.3, Xibei West Road, Beijing Chaoyang District. DETAILED DESCRIPTION

[0020] The present application provides a preparation method of soft jujube kiwi fruit preserves, comprising: washing, polishing and peeling, pretreating soft jujube kiwi fruit, then performing twice solid state fermentation, and then performing cycle drying-softening, packaging to obtain the soft jujube kiwi fruit preserves; the twice solid state fermentation comprises: inoculating 2-5% of Saccharomyces cerevisiae liquid into the pretreated soft jujube kiwi fruit, then performing fermentation at 25-30°C for 3-5d, inoculating 3-8% of Pediococcus ethanolidurans liquid, then performing fermentation at 32-37°C for 7-15d.

[0021] The washing step of the soft jujube kiwi fruit is not particularly limited in the present application, and a conventional washing step in the art can be used. As an implementable mode, the washing step is as follows: selecting soft jujube kiwi fruit raw materials without insect damage, with tender green color, firm flesh, uniform size and maturity of 8-9, to ensure the quality and taste, soaking in 1%-3% dilute salt water for 10-30min, and then washing. The washing step of the present application can clean and sterilize the surface of the soft jujube kiwi fruit, and reduce the invasion of pathogenic bacteria.

[0022] After the washing, a polishing and peeling step is preferably performed: using a polisher to gently remove the epidermis, the inclination angle of the grinding head is 30-90°, the grinding head stroke is 20-50mm, the main shaft rotation speed is 2000-5000r / min, and the grinding is stopped until the green epidermis is just removed and the flesh is exposed.

[0023] After the polishing and peeling, a pretreatment step is preferably performed: irradiation softening and microwave curing; the irradiation softening is preferably treated by using a cobalt 60, and the irradiation dose is preferably 3.0-5.0kGy, more preferably 4.0kGy; the microwave curing preferably comprises: first stage treatment at 40-60°C for 3-5min, and second stage treatment at 80-100°C for 1-2min. The cobalt 60 irradiation technology has strong penetration, and the gamma rays act on the cell wall of the fruit, effectively degrading and depolymerizing the large molecular polysaccharides of the cell wall, improving the solubility of pectin, relaxing the cell wall, loosening the cell structure, and promoting the fruit softening, but ensuring that the shape and nutritional components of the fruit are not damaged.

[0024] The pretreated soft jujube is inoculated with 2-5% by mass of a Saccharomyces cerevisiae bacterial liquid, and is fermented at 25-30 DEG C for 3-5 days, then is inoculated with 3-8% of an ethanol-tolerant Pediococcus liquid, and is fermented at 32-37 DEG C for 7-15 days.

[0025] Preparation of the Saccharomyces cerevisiae bacterial liquid preferably comprises: adding 30-50% of soft jujube juice to wort, and culturing at 25-30 DEG C for 3-5 days, so that the bacterial count reaches 10 7 ~ 10 8 CFU / mL; preparation of the wort preferably comprises: 20 g of malt powder, 1 g of peptone acid, 1 g of glucose, 15 g of agar, and 1000 mL of distilled water; the inoculation amount of the Saccharomyces cerevisiae bacterial liquid is preferably 2%-5%, and more preferably 3%; preparation of the ethanol-tolerant Pediococcus liquid preferably comprises: adding 30%-50% of soft jujube juice to MR broth, and culturing at 32-37 DEG C for 2-3 days, so that the bacterial count reaches 10 8 ~ 10 9 CFU / mL; the soft jujube juice is preferably squeezed from peeled soft jujube and pure water at a volume ratio of 1:5-8, with 2%-5% (by weight) of brown sugar being added; the inoculation amount of the ethanol-tolerant Pediococcus bacterial liquid is preferably 3%-8%, and more preferably 5%.

[0026] The method of combined solid-state fermentation of Saccharomyces cerevisiae and ethanol-tolerant Pediococcus bacteria is adopted, the soft jujube becomes softer in texture, has better taste, higher acidity and richness, maintains a bright yellow appearance, and has some fermented aroma. In addition, the chewability of the soft jujube is better, the water content is slightly reduced, the nutritional value is maintained, and the probiotic content is increased.

[0027] The soft jujube after the two solid-state fermentations is preferably subjected to a drying cycle of drying-softening. The cycle of drying-softening preferably comprises: drying and roller-softening the soft jujube after solid-state fermentation, and repeating for 3-5 times, until the water content of the soft jujube is 15-20%.

[0028] The drying process preferably includes instant air heating and low-temperature air blowing. The temperature of the instant air heating is preferably 150-200℃, more preferably 180℃, and the time is preferably 5-8min, more preferably 7min. The temperature of the low-temperature air blowing is preferably 40-45℃, more preferably 43℃, and the time is preferably 3-4h, more preferably 3.5h.

[0029] During the instant air heating process, the fermented soft kiwi fruit is placed in a hot air circulation system. The heat from the hot air causes the water inside the fruit to evaporate, resulting in overall water loss. First, the hot air circulation system generates hot air, which is circulated and delivered to the area where the fruit is located. When the fruit is exposed to the hot air, heat penetrates into the fruit, causing the water inside the fruit to heat up and evaporate rapidly. As the water evaporates, the humidity inside the fruit gradually decreases, leading to overall water loss of the fruit. This process continues until the fruit reaches the desired level of dryness.

[0030] The low-temperature air blowing drying is achieved by using an air blower to continuously blow air onto the preserved fruit at a relatively low temperature. The low-temperature air blowing drying is relatively mild, which can avoid excessive drying of the surface of the preserved fruit, thereby maintaining the texture and taste of the preserved fruit, and avoiding the adverse effects of high temperature on the activity of probiotics. The low-temperature air blowing drying can ensure that the water inside the preserved fruit gradually migrates to the surface, so as to dehydrate more uniformly. In addition, appropriate drying time is also crucial, which needs to ensure that the probiotics are not affected by heat during the drying process, thereby maintaining the activity of the probiotics.

[0031] After the drying process, the soft kiwi fruit is preferably rolled back to softness. The rolling back to softness preferably includes: rolling the dried soft kiwi fruit, spraying ethanol-tolerant Pediococcus liquid, and softening at room temperature and in the dark for 5-20h. The rolling force is preferably 5-20N, more preferably 10N, the working roll gap is preferably 5-20mm, more preferably 10mm, and the linear speed is preferably 2.0-5.0mm / s, more preferably 3.0mm / s.

[0032] After the rolling back to softness, the soft kiwi fruit is preferably packaged. The packaging step is not particularly limited in the present application, and conventional commercially available products in the art can be used. As an implementable way, the packaging step is: coating the soft kiwi fruit after softening with a layer of vitamin E containing 50-100mg / kg of 2,6-di-tert-butyl-4-methylphenol (BHT), and vacuum packaging with an aluminum foil breathable packaging bag with a thickness of 15-30μm and an oxygen transmission rate of less than 0.05cm 3 / (m 2 ·24h·0.1MPa). It can effectively reduce the oxygen content in the preserved fruit, slow down the oxidation reaction and microbial growth, protect the color and water loss, and prolong the shelf life of the preserved fruit.

[0033] The ethanol-tolerant Pediococcus cereus spore liquid of the present application can enhance the taste, flavor and nutritional value of preserved fruits, and through spraying the ethanol-tolerant Pediococcus cereus spore liquid, the soft jujube can be further fermented in the softening step, the texture of the fruit product can be improved, the release and transformation of nutritional components such as certain bioactive substances can be promoted, and the preservation of the product can also be improved.

[0034] After fermentation and drying, the moisture content in the preserved fruits can be further reduced, which is beneficial to inhibit the growth of microorganisms, prolong the shelf life, and form a unique dried fruit taste and flavor.

[0035] The main functions of the softening after drying include: 1) restoring the taste: the preserved fruits after drying often become very hard, and the softening can make the preserved fruits absorb an appropriate amount of water to restore the softness suitable for eating and improve the eating experience of consumers; 2) balancing the water distribution: the softening process helps to redistribute the internal water of the preserved fruits, making the internal and external water of the fruit pulp more uniform, avoiding the shrinkage and hardening of the fruit pulp caused by rapid dehydration; 3) shaping: the preserved fruits after softening are easier to shape to achieve better appearance quality; 4) quality control: unqualified products can be selected again during the softening process to ensure the quality of the final product.

[0036] The present application also provides the soft jujube preserved fruits prepared by the above preparation method.

[0037] The soft jujube preserved fruits prepared by the preparation method of the present application have a full tissue morphology, do not flow sugar, do not stick to the hand, are sour and sweet, have a moderate hardness, are suitable for both the old and the young, have a strong soft jujube flavor, and meet the requirements of the public for the quality and taste of preserved fruits.

[0038] In the present application, all raw material components are commercially available products well known to those skilled in the art unless otherwise specified.

[0039] The technical solutions in the present application will be clearly and completely described below in combination with the embodiments in the present application. Obviously, the described embodiments are only some of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0040] In the following examples, all are conventional methods unless otherwise specified.

[0041] In the following examples, the materials, reagents, etc. used are commercially available unless otherwise specified.

[0042] Example 1

[0043] (1) Raw materials and treatment

[0044] The soft jujube kiwifruit fruits without insect damage, tender green color, firm flesh, uniform size, and maturity of 8-9 are soaked in 2% dilute salt water for 20 minutes and then cleaned;

[0045] (2) Polishing and peeling

[0046] The epidermis is gently removed by a polisher, the inclination angle of the grinding head is 30-90°, the grinding head stroke is 20-50 mm, the main shaft rotation speed is 3000 r / min, and the polishing is performed until the green epidermis is just removed and the flesh is exposed;

[0047] (3) Pretreatment

[0048] Radiation softening: the soft jujube kiwifruit after polishing and peeling is irradiated by a cobalt 60 until the radiation dose is 4.0 kGy;

[0049] Microwave ripening: the soft jujube kiwifruit after radiation softening is treated at 50℃ for 4 minutes and then at 90℃ for 1.5 minutes;

[0050] (4) Two-stage solid-state fermentation

[0051] Preparation of soft jujube kiwifruit juice: the peeled soft jujube kiwifruit fruits are juiced with pure water at a weight ratio of 1:6, and 3% (by weight) brown sugar is added;

[0052] Preparation of Saccharomyces cerevisiae (CGMCC No. 2.1364) bacterial liquid: 40% soft jujube kiwifruit juice (the volume ratio of malt juice to soft jujube kiwifruit juice is 3:2) is added to malt juice (malt powder 20 g, peptone acid 1 g, glucose 1 g, agar 15 g, distilled water 1000 mL), and after inoculation of Saccharomyces cerevisiae, the culture is incubated at 25-30℃ for 4 days, and the bacterial count reaches 7.8×10 7 CFU / mL;

[0053] Preparation of Pediococcus ethanolidurans (CGMCC No. 29506) bacterial liquid: 40% soft jujube kiwifruit juice (the volume ratio of MR broth to soft jujube kiwifruit juice is 3:2) is added to MR broth, and after inoculation of Pediococcus ethanolidurans, the culture is incubated at 32-37℃ for 2.5 days, and the bacterial count reaches 7.3×10 8 CFU / mL;

[0054] First-stage solid-state fermentation: 4% Saccharomyces cerevisiae bacterial liquid is inoculated into the pretreated soft jujube kiwifruit fruits, and the fermentation is carried out at 25-30℃ for 4 days;

[0055] Second-stage solid-state fermentation: 5% Pediococcus ethanolidurans bacterial liquid is inoculated into the soft jujube kiwifruit fruits after the first-stage solid-state fermentation, and the fermentation is carried out at 32-37℃ for 10 days;

[0056] (5) Circulating drying-softening

[0057] The dried soft jujube fruits after solid fermentation are softened by rolling for 4 times;

[0058] The drying is instantaneous air heating combined with low-temperature blast heating;

[0059] The instantaneous air heating is that the fermented soft jujube fruits are treated at 170℃ for 7 min;

[0060] The low-temperature blast heating is that the soft jujube fruits after the instantaneous air heating are treated at 43℃ for 3.5 h;

[0061] The softening by rolling is that the dried soft jujube fruits are rolled, the rolling pressure is set to be 10 N, the working roll gap is set to be 10 mm, the rolling linear velocity is set to be 3.0 mm / s, the rolling times are 4, and the ethanol-resistant Pediococcus cereus bacterial liquid is sprayed, and the softened fruits are kept at room temperature in dark for 10 h;

[0062] (6) Packaging

[0063] The softened soft jujube fruits are smeared with a layer of vitamin E (containing 50-100 mg / kg of 2,6-di-tert-butyl-4-methylphenol BHT), and the fruits are packaged in an aluminum foil breathable packaging bag (the bag thickness is 15-30 μm, the oxygen permeation rate is less than 0.05 cm 3 / (m 2 ·24h·0.1MPa), and the bag is vacuumized.

[0064] Example 2

[0065] (1) Raw materials and treatment

[0066] The soft jujube fruits without insect and rot, with tender green color, firm flesh, uniform size, and maturity of 8-9 are soaked in 1% dilute salt water for 30 min, and then cleaned;

[0067] (2) Polishing and peeling

[0068] The surface is gently removed by a polisher, the grinding head inclination angle is 30-90°, the grinding head stroke is 20-50 mm, the main shaft rotation speed is 2000 r / min, and the polishing is stopped until the green surface is just removed and the flesh is exposed;

[0069] (3) Pretreatment

[0070] The soft jujube fruits after polishing and peeling are irradiated by a cobalt 60 until the irradiation dose is 5.0 kGy;

[0071] The irradiated soft jujube fruits are treated at 40℃ for 5 min, and then treated at 80℃ for 2 min;

[0072] (4) Twice solid state fermentation

[0073] Preparation of Actinidia deliciosa juice: peel the Actinidia deliciosa fruit and squeeze juice with pure water at a weight ratio of 1:5, and add 2% (by weight) brown sugar;

[0074] Preparation of Saccharomyces cerevisiae (CGMCC No. 2.1364) bacterial solution: add 40% Actinidia deliciosa juice (volume ratio of wort to Actinidia deliciosa juice is 3:2) to wort (malt powder 20 g, peptone acid 1 g, glucose 1 g, agar 15 g, distilled water 1000 mL), inoculate Saccharomyces cerevisiae, and culture at 25-30°C for 3 days, with a bacterial count of 2.3 x 10 7 CFU / mL;

[0075] Preparation of Pediococcus ethanolidurans (CGMCC No. 29506) bacterial solution: add 40% Actinidia deliciosa juice (volume ratio of MR broth to Actinidia deliciosa juice is 3:2) to MR broth, inoculate Pediococcus ethanolidurans, and culture at 32-37°C for 2 days, with a bacterial count of 1.9 x 10 8 CFU / mL;

[0076] First solid state fermentation: inoculate 4% Saccharomyces cerevisiae bacterial solution into pretreated Actinidia deliciosa fruit, and ferment at 25-30°C for 3 days;

[0077] Second solid state fermentation: inoculate 5% Pediococcus ethanolidurans bacterial solution into Actinidia deliciosa fruit after first solid state fermentation, and ferment at 32-37°C for 7 days;

[0078] (5) Cycle of drying and softening

[0079] First, dry the Actinidia deliciosa fruit after solid state fermentation, then roll and soften, and cycle 3 times;

[0080] Instant air heating: treat the fermented Actinidia deliciosa fruit at 150°C for 8 min;

[0081] Low-temperature air heating: treat the Actinidia deliciosa fruit after instant air heating at 40°C for 4 h;

[0082] Rolling and softening: roll the dried Actinidia deliciosa fruit: set the rolling pressure to 5N, the working roll gap to 5mm, the rolling line speed to 2.0 mm / s, roll 3 times, spray Pediococcus ethanolidurans bacterial solution (step 4), and soften at room temperature in the dark for 5 h;

[0083] (6) Packaging

[0084] The softened kiwifruit is coated with vitamin E (containing 50-100 mg / kg of 2,6-di-tert-butyl-4-methylphenol BHT), and is vacuum packaged in an aluminum foil permeable packaging bag (bag thickness 15-30 μm, oxygen permeability less than 0.05 cm 3 / (m 2 ·24h·0.1MPa)) vacuum packaging.

[0085] Example 3

[0086] (1) Raw material and treatment

[0087] The kiwifruit is selected for no insect damage, tender green color, firm flesh, uniform size, and maturity of 8-9, and is cleaned after being soaked in 3% dilute salt water for 10 min;

[0088] (2) Peeling, soaking, and freezing

[0089] The surface is gently removed with a sander, the sander head is inclined at an angle of 30-90°, the sander head travels 20-50 mm, the main shaft rotates at 5000 r / min, and the sander is used until the green surface is just removed and the flesh is exposed;

[0090] (3) Pretreatment

[0091] Softening by irradiation: the peeled and sanded kiwifruit is irradiated by a cobalt 60 source until the irradiation dose is 3.0 kGy;

[0092] Microwave ripening: the softened kiwifruit is treated at 60°C for 3 min and then at 100°C for 1 min;

[0093] (4) Two-stage solid fermentation

[0094] Preparation of kiwifruit juice: the peeled kiwifruit is juiced with pure water at a weight ratio of 1:8, and 5% (by weight) brown sugar is added;

[0095] Preparation of Saccharomyces cerevisiae (CGMCC No. 2.1364) bacterial solution: 40% kiwifruit juice is added to malt juice (malt powder 20 g, peptone 1 g, glucose 1 g, agar 15 g, distilled water 1000 mL) at a volume ratio of 3:2, and Saccharomyces cerevisiae is inoculated and cultured at 25°C for 5 d, with a bacterial count of 1.3 x 10 8 CFU / mL;

[0096] Preparation of Pediococcus acidilactici (CGMCC No. 29506) bacterial solution: 40% kiwifruit juice is added to MR broth at a volume ratio of 3:2, and Pediococcus acidilactici is inoculated and cultured at 32°C for 3 d, with a bacterial count of 9.7 x 108 CFU / mL;

[0097] First solid state fermentation: inoculate Saccharomyces cerevisiae bacteria liquid with a mass fraction of 4% into the pretreated soft jujube fruits, and ferment at 25°C for 5d;

[0098] Second solid state fermentation: inoculate Pediococcus ethanolidurans bacteria liquid with a mass fraction of 5% into the soft jujube fruits after the first solid state fermentation, and ferment at 32°C for 15d;

[0099] (5) Cycle of drying and softening

[0100] First, dry the soft jujube fruits after solid state fermentation, and then soften by rolling, for 5 cycles;

[0101] Drying is instantaneous air heating combined with low-temperature air blowing heating;

[0102] Instantaneous air heating: treat the fermented soft jujube fruits at a temperature of 200°C for 5min;

[0103] Low-temperature air blowing heating: treat the soft jujube fruits after instantaneous air heating at 40°C for 4h;

[0104] Softening by rolling: roll the fermented soft jujube fruits, with a rolling pressure of 20N, a working roll gap of 20mm, a rolling linear speed of 5.0mm / s, 5 times of rolling, and spraying Pediococcus ethanolidurans bacteria liquid in step (4), and then soften at room temperature in the dark for 20h;

[0105] (6) Packaging

[0106] Apply a layer of vitamin E (containing 50-100mg / kg of 2,6-di-tert-butyl-4-methylphenol BHT) to the softened soft jujube fruits, and then vacuum package using an aluminum foil breathable packaging bag (bag thickness of 15-30μm, oxygen permeation rate less than 0.05cm 3 / (m 2 ·24h·0.1MPa).

[0107] Comparative Example 1

[0108] The specific implementation is the same as that of Example 1, except that no fermentation is performed.

[0109] Comparative Example 2

[0110] The specific implementation is the same as that of Example 1, except that only one solid state fermentation of Saccharomyces cerevisiae is performed.

[0111] Comparative Example 3

[0112] The specific implementation is the same as that of Example 1, except that only one solid-state fermentation of lactic acid bacteria is performed.

[0113] Comparative Example 4

[0114] The specific implementation is the same as that of Example 1, except that the Saccharomyces cerevisiae is replaced by Saccharomyces cerevisiae BNCC186060.

[0115] Comparative Example 5

[0116] The specific implementation is the same as that of Example 1, except that the Pediococcus ethanolidurans is replaced by Lactobacillus plantarum subsp. plantarum BNCC187903.

[0117] Comparative Example 6

[0118] The specific implementation is the same as that of Example 1, except that the drying method is oven baking.

[0119] Test Example 1

[0120] Influence of different fermentation methods on physicochemical properties of soft jujube before and after fermentation

[0121] The hardness of soft jujube before and after fermentation in Example 1 and Comparative Examples 1-5, and the contents of soluble solids, titratable acid, citric acid, malic acid, lactic acid, vitamin C, total flavonoids and total phenols were detected, and the specific results are shown in Table 1.

[0122] Among them, citric acid detection adopts high performance liquid chromatography; malic acid detection adopts high performance liquid chromatography; vitamin C detection adopts ultraviolet spectrophotometry; flavonoid detection adopts ultraviolet spectrophotometry; soluble solid detection adopts refractometer method; total phenol detection adopts total phenol (TP) kit; hardness determination adopts Newton hardness tester method; aroma determination adopts electronic nose method; and moisture content determination adopts drying method.

[0123] Table 1 Influence of different fermentation methods on physicochemical properties of soft jujube before and after fermentation

[0124] Test index Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Comparative Example 5 Comparative Example 6 Hardness (kg / cm 2 )]]> 2.53 8.7 3.05 2.88 9.27 4.64 10.58 Soluble solids (%) 15.89 7.47 11.78 11.65 9.76 12.73 14.33 Titration acid (%) 0.65 1.21 0.94 0.87 1.04 2.83 1.3 Citric acid (mg / g) 3.76 12.87 10.10 7.89 11.98 8.31 8.04 Malic acid (mg / g) 2.35 6.14 5.05 4.84 5.97 6.76 5.27 Lactic acid (mg / g) 0.56 0 0.31 0.35 0.29 0.33 0.40 Vitamin C (mg / g) 4.85 4.96 4.75 4.81 4.89 4.67 4.79 Total flavonoids (mg / 100g) 76.35 66.75 75.47 75.28 68.36 74.54 75.09 Total phenol (mg / g) 9.06 8.94 9.01 8.87 8.11 8.85 8.99

[0125] It can be known from the results in Table 1 that the index contents of the preserved fruits in Comparative Example 1 without fermentation are all lower than those in Example 1, and the hardness and acid content are high. The hardness and acid content are decreased in Comparative Examples 2, 3, 4 and 5 after single-bacterium fermentation, but the effect is not as good as that in Example 1. The hardness of the preserved fruits prepared by baking is too high, and the taste is not good. The hardness of the preserved fruits prepared according to the method of the present application is obviously decreased, which is 2.53 kg / cm 2The soluble solid content rises to 15.89%, the titratable acid, citric acid and malic acid contents all show a downward trend, especially the citric acid content decreases from 12.87 mg / g to 3.76 mg / g, the lactic acid production is the most, the vitamin C content is relatively high, the total flavone content rises to 76.35 mg / 100 g, and the total phenol content rises to 9.06 mg / g.

[0126] The twice solid state fermentation method of the present application makes the texture of the soft jujube kiwifruit softer, the taste better, the acidity suitable, the flavor rich, and the fruit preserve chewable and slightly lower in water content, and the nutritional value is kept unchanged and the probiotic content is increased.

[0127] Test Example 2

[0128] Sensory evaluation

[0129] Twenty food professionals are selected to score the soft jujube kiwifruit preserves prepared in Examples 1-3 and Comparative Examples 1-6 according to the sensory evaluation criteria in Table 2, and the specific results are shown in Table 3.

[0130] Table 2 Sensory evaluation criteria for soft jujube kiwifruit preserves

[0131]

[0132] Table 3 Sensory evaluation of soft jujube kiwifruit preserves in Examples 1-3 and Comparative Examples 1-6

[0133]

[0134]

[0135] According to the sensory evaluation results in Table 3, the soft jujube kiwifruit preserves prepared in the present application are uniform in color, showing a uniform bright yellow color, which may be due to the reaction of sugar and pigment in the fruit skin during fermentation. The flesh is full and has no obvious shrinkage, no mold spots, oil stains or other foreign matter. The sour and sweet is moderate, and has the unique aroma of soft jujube kiwifruit. Compared with the comparative examples, the soft jujube kiwifruit preserves prepared by the present application show obvious advantages in taste, flavor, nutritional value and sensory performance, thereby obtaining better sensory evaluation.

[0136] Although the above examples have made a detailed description of the present application, it is only a part of the examples of the present application, but not all the examples, and other examples can be obtained according to the present examples without creativity, which all belong to the protection scope of the present application.

Claims

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2. 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