Method for preparing blackened peaches based on solid state fermentation blackening

Abstract

The invention relates to a method for preparing blackened peaches based on solid state fermentation blackening, and belongs to the technical field of food processing. The method comprises the following steps: taking fresh peaches as raw materials, cleaning and peeling the peaches, and sequentially carrying out vacuum sugar infusion and ultrasonic sugar infusion treatment in a sugar solution, so as to prepare the saccharified preserved peaches. The preserved peaches are subjected to solid-state fermentation and blackening to obtain blackened peaches, and the blackened peaches are sterilized by a low-temperature plasma technology to obtain a blackened peach product which is rich in polyphenols and flavones and has improved oxidation resistance. The polyphenol content of the blackened peaches is 7.36 mg GAE / g DW, the flavone content of the blackened peaches is 3.36 mg RE / g DW, and the oxidation resistance is obviously improved. The peaches are processed by adopting a solid-state fermentation blackening method for the first time, and the deep processing technology of the peaches is innovated.

Description

Technical Field

[0001] The invention relates to a method for preparing blackened peaches based on solid-state fermentation blackening, and belongs to the technical field of food processing. Background Art

[0002] Peach is a deciduous small tree of the genus Prunus in the Rosaceae family. Peach is rich in various nutrients, such as sugars, organic acids, amino acids, niacin, vitamin C, vitamin E, polyphenols and other bioactive ingredients, as well as mineral elements such as calcium, phosphorus and iron.

[0003] In recent years, the application of new technologies in fruit and vegetable processing has not only improved the quality and safety of fruit and vegetable products, but also extended their shelf life, reduced the generation of harmful substances, and maintained the original nutrition and taste of fruits and vegetables. Vacuum infiltration sugar technology can remove part of the water in the sample in a relatively short time, improve the penetration efficiency of the sugar solution; at the same time, it reduces the contact with oxygen ions in the air, reduces the activity of polyphenol oxidase, and can maintain the original fruit flavor to a large extent. Low-temperature plasma technology has many advantages in sterilization, preservation, and pesticide degradation. It can maximize the original nutritional and sensory characteristics of food, and will not produce toxic and harmful by-products. It has high economic benefits, so low-temperature plasma technology has also been widely used in the food field.

[0004] At present, peaches are mainly eaten fresh and have a short shelf life. The peach processed products on the market mainly include peach preserves, canned peaches and peach fermented products (peach wine, peach jam, peach vinegar), etc., with few categories, resulting in a large number of fresh peaches being wasted every year due to unsalability and rotting. At present, blackened fruit and vegetable products such as black garlic, black onion, and black dates have appeared on the market. The blackening technology of fruits and vegetables is simple and convenient to operate, so it can be widely used in fruits and vegetables with high reducing sugar; however, during the blackening process, rot and mold are prone to occur; and after the sugar soaking process, the surface of the preserved fruit is prone to sand or sugar flow, affecting the quality. At present, there are no related reports on blackening peaches after they are made into preserved peaches. Summary of the invention

[0005] In view of the research and development gap in the prior art, the purpose of the present invention is to provide a method for producing blackened peaches by solid-state fermentation blackening, using peaches as raw materials and adopting solid-state fermentation blackening treatment to obtain a new type of blackened peach product.

[0006] To achieve the above object, the present invention adopts the following technical solution: The present invention provides a method for preparing blackened peaches based on solid-state fermentation blackening, comprising the following steps: (1) Pretreatment of peaches: Wash the peaches, remove the peach hairs, cut them into pieces, remove the peach pits, and set aside; (2) Preparation of peach preserves: placing the pre-treated peach flesh in a sugar solution, and sequentially subjecting the peach flesh to vacuum sugar immersion and ultrasonic sugar infiltration treatment to prepare peach preserves; and then subjecting the peach preserves to heat baking treatment; (3) Peach blackening process: The peach preserves after heat baking are sealed and fermented to blacken; (4) Sterilization process of blackened peaches: The blackened peaches are sterilized by low-temperature plasma to obtain blackened peaches.

[0007] Preferably, the conditions for the vacuum sugar infiltration treatment are: 0.06-0.075MPa vacuum degree for sugar pretreatment, time is 20-30min, sugar solution temperature is 50°C; the conditions for the ultrasonic sugar infiltration treatment are: ultrasonic sugar infiltration power 200-300W, ultrasonic sugar infiltration time 15-25 min, ultrasonic sugar infiltration temperature 30-50°C.

[0008] Preferably, in step (2), the solid-liquid ratio of the peach flesh to the sugar solution is 1:3 g / mL; the sugar solution used in the vacuum sugar infiltration treatment is composed of 2 parts of sucrose, 0.5 parts of starch syrup, 0.1 parts of betaine and 2.5-3 parts of water; the sugar solution used in the ultrasonic sugar infiltration treatment is composed of 2 parts of sucrose, 0.5 parts of starch syrup and 4-5 parts of water.

[0009] Preferably, in step (3), the moisture content of the peach preserves after heat baking is controlled at 30%-50%.

[0010] Preferably, in step (3), the fermentation blackening treatment is to seal the mixture in a sealed bag and place it in a constant temperature oven at 60-70° C. for blackening for 6-10 days.

[0011] Preferably, in step (4), the conditions for the low-temperature plasma sterilization treatment are: treatment voltage 30-40 kV, time 2-3 min.

[0012] The present invention also provides a black peach product prepared by the above method. The black peach prepared by the present invention is rich in polyphenols and flavonoids and has increased antioxidant capacity, the polyphenol content of the black peach is 7.36 mg GAE / g DW, the flavonoid content is 3.36 mg RE / g DW, and the antioxidant capacity is significantly increased.

[0013] The blackened peach prepared by the invention is prepared by adopting a solid-state fermentation blackening process, undergoing a Maillard reaction, and controlling temperature and humidity. After the fresh peach is blackened, the nutritional content and antioxidant capacity are greatly improved. The beneficial effects of the present invention are: (1) The present invention adopts the "vacuum sugar infiltration + ultrasonic sugar infiltration" linkage combination treatment method for the first time to make peach preserves, which can not only maintain the original flavor of the peaches to the greatest extent, but also remove part of the moisture in the peaches in a relatively short time. At the same time, combined with a specific concentration of sugar solution, the penetration efficiency of the sugar solution is improved, and the problems of rotting, sand return, sugar leakage, etc. in the peach meat processing process are avoided.

[0014] (2) The present invention is the first to apply solid-state fermentation melanization technology to peach processing. The melanized peach product obtained after melanization is rich in beneficial ingredients such as polyphenols and flavonoids, and has enhanced antioxidant function.

[0015] (3) The present invention uses low-temperature plasma technology to sterilize black peaches, which can not only achieve a sterilization effect, but also maintain the original nutritional and sensory characteristics of black peaches to the maximum extent, and will not produce toxic and harmful by-products, thus having high economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a physical picture of preparing blackened peaches; wherein a is fresh peach flesh; b is blackened peach; Figure 2 is the gallic acid standard curve; Figure 3 This is the standard curve of rutin. DETAILED DESCRIPTION

[0017] The technical solution of the present invention is further explained and illustrated by means of specific embodiments below.

[0018] Unless otherwise specified, all technical and scientific terms used herein have the same meanings as commonly understood by those of ordinary skill in the art to which this application belongs. As described in the background technology section, the blackened product not only has improved nutrition, but also has a unique flavor. Developing a new blackened peach product for use in the food market should have broad market prospects.

[0019] At present, there is no related report on the combination of fruit peach and melanization technology in the market. The present invention provides a method for producing melanized peaches by solid-state fermentation melanization, laying a theoretical foundation for the market launch.

[0020] In order to enable those skilled in the art to more clearly understand the technical solution of the present application, the technical solution of the present application will be described in detail below in conjunction with specific examples. The test materials used in the examples of the present invention are all conventional test materials in the field and can be purchased through commercial channels. In an embodiment of the present invention, a preparation method for producing melanized peaches by solid-liquid fermentation melanization is provided, and the specific steps are as follows: Example 1 (1) Raw material selection: Choose peaches that are highly mature, sweet, and free of external damage.

[0021] (2) Pretreatment: Wash the peaches, remove the fuzz, cut them into quarters, remove the pits, and set aside.

[0022] (3) Preparation of peach preserves: Vacuum sugar infiltration and ultrasonic sugar infiltration were carried out in sequence. The pretreated pulp was placed in sugar solution 1 (2 parts sucrose, 0.5 parts starch syrup, 0.1 parts betaine and 3 parts water) at a material-liquid ratio of 1:3 (g / mL). The pulp was soaked in sugar at a vacuum degree of 0.06 MPa for 30 minutes at a sugar solution temperature of 50°C. For ultrasonic sugar infiltration, sugar solution 2 (2 parts sucrose, 0.5 parts starch syrup and 5 parts water) was used at an ultrasonic sugar infiltration power of 300 W, a ultrasonic sugar infiltration time of 15 minutes and a ultrasonic sugar infiltration temperature of 50°C. The pulp was then placed in a 65°C oven to remove some of the moisture.

[0023] (4) Preparation of blackened peaches: The moisture content of peach preserves was controlled at 30%, placed in a sealed bag, and fermented in a constant temperature oven at a blackening temperature of 60°C for 10 days.

[0024] (5) Sterilization process of blackened peaches: The blackened peaches were sterilized by low-temperature plasma with a treatment voltage of 30 kV and a treatment time of 3 min.

[0025] Example 2 (1) Raw material selection: Choose peaches that are highly mature, sweet, and free of external damage.

[0026] (2) Pretreatment: Wash the peaches, remove the fuzz, cut them into quarters, remove the pits, and set aside.

[0027] (3) Preparation of peach preserves: Vacuum sugar infiltration and ultrasonic sugar infiltration were carried out in sequence. The pretreated pulp was placed in a sugar solution (2 parts sucrose, 0.5 parts starch syrup, 0.1 parts betaine and 2.5 parts water) at a material-liquid ratio of 1:3 (g / mL). The pulp was soaked in sugar at a vacuum degree of 0.07 MPa for 25 minutes at a sugar solution temperature of 50°C. For ultrasonic sugar infiltration, sugar solution 2 (2 parts sucrose, 0.5 parts starch syrup and 4 parts water) was used. The ultrasonic sugar infiltration power was 250W, the ultrasonic sugar infiltration time was 20 minutes, and the ultrasonic sugar infiltration temperature was 40°C. Then the pulp was placed in a 65°C oven to remove some of the moisture.

[0028] (4) Preparation of blackened peaches: The moisture content of peach preserves was controlled at 40%, placed in a sealed bag, and fermented in a constant temperature oven at a blackening temperature of 65°C for 8 days.

[0029] (5) Sterilization process of blackened peaches: The blackened peaches were sterilized by low-temperature plasma with a treatment voltage of 35 kV and a treatment time of 2.5 min.

[0030] Comparative Example 1 (1) Raw material selection: Choose peaches that are highly mature, sweet, and free of external damage.

[0031] (2) Pretreatment: Wash the peaches, remove the fuzz, cut them into quarters, remove the pits, and set aside.

[0032] (3) Preparation of peach preserves: Vacuum sugar infiltration and ultrasonic sugar infiltration were carried out in sequence. The pretreated pulp was placed in sugar solution 1 (2 parts sucrose, 0.5 parts starch syrup and 3 parts water) at a material-liquid ratio of 1:3 (g / mL). The pulp was soaked in sugar at a vacuum degree of 0.06 MPa for 30 minutes at a sugar solution temperature of 50°C. For ultrasonic sugar infiltration, sugar solution 2 (2 parts sucrose, 0.5 parts starch syrup and 5 parts water) was used at an ultrasonic sugar infiltration power of 300 W, a ultrasonic sugar infiltration time of 15 minutes and a ultrasonic sugar infiltration temperature of 50°C. The pulp was then placed in a 65°C oven to remove some of the moisture.

[0033] The other steps are the same as in Example 1.

[0034] Comparative Example 2 (1) Raw material selection: Choose peaches that are highly mature, sweet, and free of external damage.

[0035] (2) Pretreatment: Wash the peaches, remove the fuzz, cut them into quarters, remove the pits, and set aside.

[0036] (3) Preparation of peach preserves: Vacuum sugar infiltration and ultrasonic sugar infiltration were carried out in sequence. The pretreated pulp was placed in sugar solution 1 (2 parts sucrose, 0.5 parts starch syrup, 0.1 parts betaine and 3 parts water) at a material-liquid ratio of 1:3 (g / mL). The pulp was soaked in sugar at a vacuum degree of 0.06 MPa for 30 minutes at a sugar solution temperature of 50°C. The pulp was then placed in an oven at 65°C to remove some of the moisture.

[0037] 1) Preparation of blackened peaches: The moisture content of peach preserves was controlled at 30%, placed in a sealed bag, and fermented in a constant temperature oven at a blackening temperature of 60°C for 10 days.

[0038] 2) Sterilization process of blackened peaches: The blackened peaches were sterilized by low-temperature plasma with a treatment voltage of 30 kV and a treatment time of 3 min.

[0039] Effect Example The melanized peaches prepared in Examples 1 and 2 and the melanized peaches prepared in Comparative Examples 1 and 2 were tested, and a blank group was set up. After being treated according to steps 1) to 3) of Example 1, no melanization treatment was performed, and low-temperature plasma sterilization treatment was performed directly after packaging, and the treatment parameters were the same as in Example 1.

[0040] The detection method is as follows: 1. Determination method of black peach polyphenols (1) Drawing of standard curve Pipette 1 mL of 0, 0.04, 0.06, 0.08, 0.1, and 0.12 mg / mL gallic acid standard solution and 1 mL of double-diluted folin-phenol solution into a 20 mL stoppered colorimetric tube, shake well, let stand for 5 min, and then add 5 mL of 10% Na 2 CO 3 Solution. Add deionized water to the scale, shake well, place in the dark to react for 60 min, and measure the absorbance at 760 nm with a spectrophotometer; the gallic acid standard curve is as follows Figure 2 shown.

[0041] (2) Determination of polyphenol content Pipette 1 mL of sample extract and 1 mL of double-diluted Folin-phenol reagent into a 20 mL stoppered colorimetric tube, shake well, and let it react for 5 min. Add 5 mL of 10% Na 2 CO 3 The solution was diluted to 20 mL with deionized water, shaken, and placed in the dark for 60 min. The absorbance was measured at 760 nm using a spectrophotometer. The polyphenol content of the sample was expressed as gallic acid equivalent (mg GAE / g DW).

[0042] Polyphenol content (mg GAE / g DW) = (1) In formula (1), m 0 : The mass of the sample, in g; m 1 : The mass of gallic acid, in mg; v 1 : Sample volume, in mL; v 2 : Volume of sample extract to be pipetted, in mL.

[0043] 2 Determination method of flavonoids in black peach (1) Drawing of standard curve Take 2.0 mL of 0.02, 0.04, 0.06, 0.08, and 0.1 mg / mL rutin standard solutions and 0.6 mL of 5% NaNO 2 solution and 0.6 mL 10% Al(NO 3 ) 3The solution was placed in a 20 mL stoppered colorimetric tube, shaken and allowed to stand for 6 min. After completion, 8.0 mL of 4% NaOH solution was added and the volume was fixed to the mark with 70% ethanol solution. Shake well and allow to stand for 15 min. The absorbance was measured at 510 nm. The standard curve of rutin is as follows: Figure 3 shown.

[0044] (2) Determination of flavonoid content Take 2.0 mL of sample extract and 0.6 mL of 5% NaNO 2 solution and 0.3 mL 10% Al(NO 3 ) 3 The solution was placed in a 20 mL stoppered colorimetric tube, shaken, and allowed to react for 6 min. After completion, 8.0 mL of 4% NaOH solution was added, and the volume was fixed to the mark with 70% ethanol solution. Shake well, let it react for 15 min, and measure the absorbance at 510 nm. The flavonoid content in the sample was expressed as rutin equivalent (mg RE / g DW).

[0045] Flavonoid content (mg RE / g DW) = (2) In formula (2), m 0 : The mass of the sample, in g; m 1 : The mass of rutin, in mg; v 1 : Sample volume, in mL; v 2 : Volume of sample extract to be pipetted, in mL.

[0046] 3 Determination of antioxidant activity of black peach 10 mL of sample extract was taken and weighed respectively, and the density was calculated. Repeat 3 times and take the average value. The absorbance values ​​corresponding to sample extracts of different concentrations were measured to calculate the DPPH and ABTS clearance rates; the DPPH and ABTS clearance rates were plotted as the ordinate and the sample concentration as the abscissa, and the concentration of the sample extract was calculated when the clearance rate was 50%.

[0047] (1) Determination of DPPH free radical scavenging rate The determination was carried out according to the method in the literature. Take 0.1 mL of sample extracts of different concentrations, mix with 5.0 mL of DPPH ethanol solution (39.4 mg / mL), and stand for 30 minutes at room temperature in the dark. Adjust to 0 with deionized water, and measure the absorbance at 517 nm.

[0048] DPPH free radical scavenging rate / %= (3) In formula (3), A 0 : Absorbance measured at 517 nm after 1 mL of anhydrous ethanol was mixed with 5 mL of DPPH and treated; A 1 : Absorbance measured at 517 nm after 1 mL of sample solution was mixed with 5 mL of DPPH and treated.

[0049] (2) Determination of ABTS free radical scavenging rate The determination was carried out according to the method in the literature. ABTS solution was diluted 53 times with 80% ethanol solution. 0.04 mL of sample extracts of different concentrations and 5 mL of ABTS solution were respectively taken, mixed, kept in the dark for 9 min, adjusted to 0 with deionized water, and the absorbance value was measured at 734 nm.

[0050] ABTS free radical scavenging rate (%) = (4) In formula (4), A 0 : 0.04 mL of deionized water was mixed with 5 mL of ABTS, and the absorbance was measured at 734 nm after treatment; A 1 : 0.04 mL of sample was mixed with 5 mL of ABTS and then treated, and the absorbance was measured at 734 nm).

[0051] The results are in IC 50 The value (the concentration of the sample when the clearance rate is 50%) is expressed according to the IC 50 The value of IC 50 The smaller it is, the stronger its free radical scavenging ability is.

[0052] The results shown in Table 1 are obtained: Table 1: Comparison of ingredients and antioxidant capacity of black peach in various examples As shown in Table 1 above, the black peach prepared by the present invention has a maximum polyphenol content of 7.36 mg / g, a flavonoid content of 3.36 mg / g, a DPPH clearance rate Ic50 value of 0.604 mg / g, and an ABTS clearance rate Ic50 value of 0.721 mg / g. The smaller the Ic50 value, the stronger the antioxidant capacity. The black peach prepared by the present invention has stronger nutrition and functionality.

[0053] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing melanized peaches based on solid-state fermentation melanization, characterized in that: The following steps are involved: (1) Pretreatment of peaches: Wash the peaches, remove the peach hairs, cut them into pieces, remove the peach pits, and set aside; (2) Preparation of peach preserves: placing the pre-treated peach flesh in a sugar solution, and sequentially subjecting the peach flesh to vacuum sugar immersion and ultrasonic sugar infiltration treatment to prepare peach preserves; and then subjecting the peach preserves to heat baking treatment; (3) Peach blackening process: The peach preserves after heat baking are sealed and fermented to blacken; (4) Sterilization process of blackened peaches: The blackened peaches are sterilized by low-temperature plasma to obtain blackened peaches.

2. The method according to claim 1 or 2, characterized in that: The conditions for the vacuum sugar infiltration treatment are: 0.06-0.075MPa vacuum for sugar pretreatment, time is 20-30min, sugar solution temperature is 50°C; the conditions for the ultrasonic sugar infiltration treatment are: ultrasonic sugar infiltration power 200-300W, ultrasonic sugar infiltration time 15-25 min, ultrasonic sugar infiltration temperature 30-50°C.

3. The method according to claim 2, characterized in that In step (2), the material-liquid ratio of peach flesh to sugar solution is 1:3 g / mL; the sugar solution used in the vacuum sugar infiltration treatment is composed of 2 parts of sucrose, 0.5 parts of starch syrup, 0.1 parts of betaine and 2.5 parts of water; the sugar solution used in the ultrasonic sugar infiltration treatment is composed of 2 parts of sucrose, 0.5 parts of starch syrup and 5 parts of water.

4. The method according to any one of claims 1 to 3, characterized in that: In step (3), the moisture content of the peach preserves after heat baking is controlled at 30%-50%.

5. The method according to claim 1 or 4, characterized in that: In step (3), the fermentation blackening treatment is to seal the mixture in a sealed bag and place it in a constant temperature oven at 60-70°C for blackening for 6-10 days.

6. The method according to any one of claims 1 to 5, characterized in that: In step (4), the conditions for the low-temperature plasma sterilization treatment are: treatment voltage 30-40 kV, time 2-3 min.

7. A blackened peach prepared by the method according to any one of claims 1 to 6.

Images