Tissue hardening technology for maintaining texture of shepherd's purse product

Abstract

The invention relates to a tissue hardening technology for maintaining the texture of a shepherd's purse product, and belongs to the field of agricultural product processing. The method comprises the specific steps of primary screening and grading of shepherd's purse, cleaning, ultrasonic-assisted dipping, blanching, cooling, quick-freezing, packaging and storing. By adopting the method, the problems of tissue softening and active substance loss of the shepherd's purse raw material in the processing processes of blanching and the like are effectively solved, the obtained shepherd's purse product is complete in tissue structure, small in color change, high in bioactive substance retention rate, high in relative content of aroma components and good in antioxidant activity, and the retention rate of Vc and chlorophyll is increased by 15% or above; the texture of the shepherd's purse product is effectively maintained and the commodity value of the shepherd's purse processed product is improved.

Description

Technical Field

[0001] This invention belongs to the field of agricultural product processing, and specifically relates to a tissue hardening technology for maintaining the texture of shepherd's purse products. Background Technology

[0002] Shepherd's purse [Capsella bursa-pastoris (L.) Medic] is an annual or biennial herbaceous plant belonging to the Brassicaceae family, also known as chicken heart vegetable, shepherd's purse, and pillow grass. Shepherd's purse is rich in various organic acids and amino acids, and its inorganic components, such as potassium, calcium, sodium, and iron, are relatively high. The tender stems and leaves are edible, and the whole plant is used medicinally, possessing diuretic and anti-edema properties, as well as effects on improving eyesight and stopping bleeding. It is an important fresh and processed vegetable in my country. Shepherd's purse is popular with consumers due to its unique flavor and abundant bioactive substances. However, its production and sales are seasonal, it does not store well, its quality deteriorates quickly, and its shelf life is short. Processing shepherd's purse into frozen products, fillings, etc., is an effective way to extend its shelf life. Blanching is a common pretreatment method for shepherd's purse products. It softens the tissue, improves permeability, enhances heat and mass transfer, and increases the rate of water diffusion. Simultaneously, it inactivates peroxidase activity, inhibiting enzymatic browning and undesirable flavors, thus improving color. Furthermore, it kills some microorganisms, reducing the initial microbial colony count and maintaining the quality of shepherd's purse. However, during or after blanching, vegetable raw materials are prone to cell membrane rupture, loss of cell turgor pressure, and cell wall contraction. Simultaneously, due to the increased solubility of high molecular weight pectin, the pectin substances binding cells undergo β-elimination degradation, reducing intercellular bonding and causing cell separation. This results in softening of the vegetable texture, loss of color, and significant loss of heat-sensitive bioactive substances such as vitamin C, chlorophyll, carotenoids, and flavonoids. Therefore, inventing a tissue hardening technology to maintain the texture of vegetable products is of great significance for improving their quality.

[0003] This invention utilizes ultrasonic-assisted impregnation to pre-treat fresh shepherd's purse, reducing the loss of heat-sensitive bioactive substances during blanching, maintaining the texture of the shepherd's purse product, and increasing the commercial value of processed shepherd's purse products. Summary of the Invention

[0004] The purpose of this study is to address the problems of softening, color deterioration, and severe loss of bioactive substances in shepherd's purse after blanching pretreatment. This research aims to develop a tissue hardening technology to maintain the texture of shepherd's purse products, providing technical support for improving the quality of processed shepherd's purse products. To solve the above problems, this study discloses a tissue hardening technology for maintaining the texture of shepherd's purse products, including steps such as initial screening and grading, washing, ultrasonic-assisted soaking, blanching, cooling, quick-freezing, packaging, and storage.

[0005] A tissue hardening technique for maintaining the texture of shepherd's purse products, the specific steps of which are as follows:

[0006] (1) Initial screening and grading: Fresh shepherd's purse raw materials without mechanical damage are classified according to leaf size;

[0007] (2) Cleaning: The graded shepherd's purse is cleaned in three sections using a continuous water bubble turbine sludge washing machine. The entire cleaning process is controlled within 6 to 7 minutes.

[0008] (3) Ultrasonic-assisted impregnation: The washed shepherd's purse was placed in a solution of 0.5%–2% (w / v) calcium chloride, 1%–3% (w / v) glucose, or 0.5%–3% (w / v) sodium alginate at a material-to-liquid ratio of 1:20, and ultrasonic-assisted impregnation was performed at an ultrasonic intensity of 0.2 W / cm. 2 ~1.0W / cm 2 Time: 5-15 minutes;

[0009] (4) Secondary soaking: Take out the shepherd's purse after ultrasonic soaking, rinse off the residual liquid on the surface, and place it again in a 0.1% to 0.5% (w / v) calcium chloride solution with a material-to-liquid ratio of 1:20 for 10 min to 30 min;

[0010] (5) Blanching: After soaking, the shepherd's purse is sent to the blanching machine via conveyor belt for blanching at a temperature of 94℃~98℃ for 40s~60s.

[0011] (6) Cooling: After blanching, the shepherd's purse is immediately subjected to forced cooling with cold water and flowing ice water for 60s to 120s, so that the temperature of the shepherd's purse drops to below 10℃;

[0012] (7) Quick-freezing: Before quick-freezing, the quick-freezing room is pre-cooled, and the shepherd's purse is quick-frozen at a temperature of -40℃ to -35℃ for 5 hours to 7 hours, so that the temperature of the center of the shepherd's purse pieces drops to below -18℃.

[0013] (8) Packaging and storage: Demolding of shepherd's purse in ice water at 0℃~5℃, the ambient temperature should be controlled below 10℃, and the quick-frozen shepherd's purse pieces after demolding should be packaged directly and stored at -20℃.

[0014] Beneficial effects of the present invention

[0015] (1) The present invention provides a tissue hardening technology for maintaining the texture of shepherd's purse products. It improves the formation of raw material texture by targeting the traditional blanching process. It uses calcium chloride, glucose or sodium alginate as the impregnation solution. The glucose or sodium alginate cross-links with calcium chloride to form an "eggshell structure" to protect the shepherd's purse tissue. This three-dimensional network has thermal irreversibility, which can reduce the dissolution of pectin during high-temperature blanching. Furthermore, through secondary calcium chloride impregnation, the calcium ions cross-link endogenous pectin and exogenous carboxyl-containing polysaccharides to form calcium gel, which strengthens the cytoskeleton and fills the gaps in the cytoskeleton to harden the shepherd's purse tissue, reduce damage to the shepherd's purse tissue, protect the shepherd's purse cells and reduce the loss of active substances.

[0016] (2) The present invention uses ultrasonic treatment to assist the impregnation process, and forms microchannels through ultrasonic cavitation effect, thereby improving the mass transfer rate of the impregnation process and accelerating the rate at which calcium chloride, glucose or sodium alginate penetrates into the leaf tissue, thus effectively improving the impregnation effect.

[0017] (3) The present invention provides a tissue hardening technology for maintaining the texture of shepherd's purse products. In response to the defects of the traditional blanching process that cause the raw materials to become soft and lose their hardness, the present invention uses ultrasonic-assisted calcium chloride, glucose or sodium alginate impregnation to maintain the tissue structure of the raw materials, reduce the solubility of cell wall pectin during the blanching process, and strictly control the blanching temperature, time and cooling temperature and time to effectively prevent the raw materials from becoming soft. The resulting shepherd's purse products have a complete tissue structure, little color change, high retention rate of bioactive substances, high relative content of aroma components and good antioxidant activity. Among them, the retention rate of vitamin C and chlorophyll is increased by more than 15%.

[0018] (4) This invention standardizes the entire process of shepherd's purse initial screening and grading, washing, ultrasonic-assisted soaking, blanching, cooling, quick-freezing, packaging and storage. Initial screening and grading reduces the impact of mechanical damage on the ultrasonic combined soaking effect; a continuous water bubble turbine mud and sand washing machine is used for three-section washing, which effectively removes mud and sand, reduces bacteria, and facilitates the flatness of shepherd's purse leaves, improving the efficiency of subsequent ultrasonic soaking; ultrasonic-assisted soaking and secondary soaking improve soaking efficiency; the temperature and time of blanching, cooling, quick-freezing, packaging and storage are strictly controlled to reduce the damage to the tissue structure of shepherd's purse during processing and improve the texture of shepherd's purse products. Attached Figure Description

[0019] Figure 1 Microscopic structures of shepherd's purse before and after treatment Detailed Implementation

[0020] Example 1: Fresh shepherd's purse raw materials without mechanical damage were classified according to leaf size; the graded shepherd's purse was washed in three sections using a continuous flow water bubble turbine sludge washing machine, with the entire washing process controlled within 6 minutes; the washed shepherd's purse was placed in a 0.5% (w / v) calcium chloride and 3% (w / v) glucose solution with a material-to-liquid ratio of 1:20 for ultrasonic-assisted impregnation, with an ultrasonic intensity of 0.5 W / cm. 2 The ultrasonic soaking time is 5 minutes; after removing the shepherd's purse, rinse off the residual liquid on the surface, and place it again in a 0.5% (w / v) calcium chloride solution with a material-to-liquid ratio of 1:20 for 30 minutes; after soaking, the shepherd's purse is sent to a blanching machine via conveyor belt for blanching at a temperature of 98℃ for 40 seconds; after blanching, the shepherd's purse is immediately subjected to forced cooling with cold water and flowing ice water for 60 seconds to lower the temperature of the shepherd's purse to below 10℃; before quick-freezing, the quick-freezing room is pre-cooled, and the shepherd's purse is quick-frozen at a temperature of -40℃ for 5 hours to lower the center temperature of the shepherd's purse pieces to below -18℃; the shepherd's purse is demolded in ice water at 0℃, and the ambient temperature should be controlled below 10℃. After demolding, the quick-frozen shepherd's purse pieces are directly packaged and stored at -20℃.

[0021] Example 2: Fresh shepherd's purse raw materials without mechanical damage were classified according to leaf size; the graded shepherd's purse was washed in three sections using a continuous flow water bubble turbine sludge washing machine, with the entire washing process controlled within 6 minutes; the washed shepherd's purse was placed in a 0.5% (w / v) calcium chloride and 0.5% (w / v) sodium alginate solution with a material-to-liquid ratio of 1:20 for ultrasonic-assisted impregnation, with an ultrasonic intensity of 0.5 W / cm. 2 The ultrasonic soaking time is 5 minutes; after removing the shepherd's purse, rinse off the residual liquid on the surface, and place it again in a 0.5% (w / v) calcium chloride solution with a material-to-liquid ratio of 1:20 for 30 minutes; after soaking, the shepherd's purse is sent to a blanching machine via conveyor belt for blanching at a temperature of 98℃ for 40 seconds; after blanching, the shepherd's purse is immediately subjected to forced cooling with cold water and flowing ice water for 60 seconds to lower the temperature of the shepherd's purse to below 10℃; before quick-freezing, the quick-freezing room is pre-cooled, and the shepherd's purse is quick-frozen at a temperature of -40℃ for 5 hours to lower the center temperature of the shepherd's purse pieces to below -18℃; the shepherd's purse is demolded in ice water at 0℃, and the ambient temperature should be controlled below 10℃. After demolding, the quick-frozen shepherd's purse pieces are directly packaged and stored at -20℃.

[0022] Example 3: Fresh shepherd's purse raw materials without mechanical damage were classified according to leaf size; the graded shepherd's purse was washed in three sections using a continuous flow water bubble turbine sludge washing machine, with the entire washing process controlled within 6 minutes; the washed shepherd's purse was placed in a 0.5% (w / v) calcium chloride and 0.5% (w / v) sodium alginate solution with a material-to-liquid ratio of 1:20 for ultrasonic-assisted impregnation, with an ultrasonic intensity of 0.5 W / cm. 2The ultrasonic soaking time is 15 minutes. After removing the shepherd's purse, rinse off the residual liquid on the surface and place it again in a 0.5% (w / v) calcium chloride solution with a material-to-liquid ratio of 1:20 for 30 minutes. After soaking, the shepherd's purse is sent to a blanching machine via conveyor belt at a temperature of 98℃ for 40 seconds. After blanching, the shepherd's purse is immediately subjected to forced cooling with cold water and flowing ice water for 60 seconds to lower the temperature of the shepherd's purse to below 10℃. Before quick-freezing, the quick-freezing room is pre-cooled, and the shepherd's purse is quick-frozen at a temperature of -40℃ for 5 hours to lower the center temperature of the shepherd's purse pieces to below -18℃. The shepherd's purse is demolded in ice water at 0℃, and the ambient temperature should be controlled below 10℃. After demolding, the quick-frozen shepherd's purse pieces are directly packaged and stored at -20℃.

[0023] The content of active substances and color of shepherd's purse products were measured, and the results are shown in the table below.

[0024] Table 1. Changes in the content of bioactive substances in shepherd's purse products

[0025]

[0026] Notes: CK represents the blank treatment; Ca represents 0.5% (w / v) calcium chloride treatment; Gl represents 3% (w / v) glucose treatment; Gl+Ca+US5 represents the treatment effect of Example 1; Al represents 0.5% (w / v) sodium alginate treatment; Al+Ca+US5 represents the treatment effect of Example 2, and Al+Ca+US15 represents the treatment effect of Example 3. Different lowercase letters in the same column represent significant differences in results (p < 0.05).

[0027] The results showed that after treatment with this invention, the content of active substances in shepherd's purse products was significantly increased, with the content of vitamin C increasing by 1.5-2.6 times, and the content of total phenols, total flavonoids and chlorophyll increasing by more than 15%. The color of shepherd's purse products was well maintained, the relative content of aroma components such as alcohols and aldehydes increased by more than 10%, and the antioxidant activity increased by more than 20%.

[0028] Table 2. Color and color difference changes of shepherd's purse products

[0029]

[0030] Notes: CK represents the blank treatment; Ca represents 0.5% (w / v) calcium chloride treatment; Gl represents 3% (w / v) glucose treatment; Gl+Ca+US5 represents the treatment effect of Example 1; Al represents 0.5% (w / v) sodium alginate treatment; Al+Ca+US5 represents the treatment effect of Example 2, and Al+Ca+US15 represents the treatment effect of Example 3. Different lowercase letters in the same column represent significant differences in results (p < 0.05).

[0031] Table 3. Changes in aroma components of shepherd's purse products

[0032]

[0033]

[0034]

[0035] Notes: CK is blank treatment; Ca is 0.5% (w / v) calcium chloride treatment; Gl is 3% (w / v) glucose treatment; Gl+Ca+US15 is the treatment effect of Example 1; Al is 0.5% (w / v) sodium alginate treatment; Al+Ca+US15 is the treatment effect of Example 2; Al+Ca+US15 is the treatment effect of Example 3.

[0036] Table 4. Changes in the antioxidant activity of shepherd's purse products

[0037]

[0038] Notes: CK is blank treatment; Ca is 0.5% (w / v) calcium chloride treatment; Gl is 3% (w / v) glucose treatment; Gl+Ca+US15 is the treatment effect of Example 1; Al is 0.5% (w / v) sodium alginate treatment; Al+Ca+US15 is the treatment effect of Example 2; Al+Ca+US15 is the treatment effect of Example 3.

Claims

1. A tissue hardening technique for maintaining the texture of shepherd's purse products, the specific processing steps of which are as follows: (1) Initial screening and grading: Fresh shepherd's purse raw materials without mechanical damage are classified according to leaf size; (2) Cleaning: The graded shepherd's purse is cleaned in three sections using a continuous water bubble turbine sludge washing machine. The entire cleaning process is controlled within 6 to 7 minutes. (3) Ultrasonic-assisted impregnation: The washed shepherd's purse was placed in a solution of 0.5%–2% (w / v) calcium chloride, 1%–3% (w / v) glucose, or 0.5%–3% (w / v) sodium alginate at a material-to-liquid ratio of 1:20, and ultrasonic-assisted impregnation was performed at an ultrasonic intensity of 0.2 W / cm. 2 ~1.0W / cm 2 Time: 5-15 minutes; (4) Secondary soaking: Take out the shepherd's purse after ultrasonic soaking, rinse off the residual liquid on the surface, and place it again in a 0.1% to 0.5% (w / v) calcium chloride solution with a material-to-liquid ratio of 1:20 for 10 min to 30 min; (5) Blanching: After soaking, the shepherd's purse is sent to the blanching machine via conveyor belt for blanching at a temperature of 94℃~98℃ for 40s~60s. (6) Cooling: After blanching, the shepherd's purse is immediately subjected to forced cooling with cold water and flowing ice water for 60s to 120s, so that the temperature of the shepherd's purse drops to below 10℃; (7) Quick-freezing: Before quick-freezing, the quick-freezing room is pre-cooled, and the shepherd's purse is quick-frozen at a temperature of -40℃ to -35℃ for 5 hours to 7 hours, so that the temperature of the center of the shepherd's purse pieces drops to below -18℃. (8) Packaging and storage: Demolding of shepherd's purse in ice water at 0℃~5℃, the ambient temperature should be controlled below 10℃, and the quick-frozen shepherd's purse pieces after demolding should be packaged directly and stored at -20℃.

2. The shepherd's purse product obtained by the production process described in claim 1.

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