A method for magnetic field-assisted cold storage and preservation of shiitake mushrooms

Abstract

This invention belongs to the field of food preservation technology and relates to a method for magnetic field-assisted cold storage preservation of shiitake mushrooms. The method includes: storing pre-treated shiitake mushroom fruiting bodies in a static magnetic field with a temperature of 3.5-4.5℃, relative humidity of 80%, and magnetic field strength of 3-9 mT, with the magnetic field direction along the Y-axis and a magnetic field uniformity greater than 90%. Pre-treatment includes selecting fresh shiitake mushrooms with a maturity of 80-90% and intact appearance, removing impurities and roots, pre-cooling at 4℃ for 1 hour, and then packaging them into food-grade polyethylene self-sealing bags with ventilation holes. This invention, through the combined use of a physical magnetic field and a low-temperature, high-humidity environment, without the addition of any chemical preservatives, can significantly inhibit post-harvest respiration and browning reactions in shiitake mushrooms, effectively reducing weight loss, maintaining the original color, firmness, and cell membrane integrity of the mushrooms, while simultaneously inhibiting lignin accumulation and chitinase activity, delaying tissue softening and aging processes, thereby significantly extending the cold storage shelf life, maintaining excellent product quality and edible flavor. The method is safe, environmentally friendly, and residue-free.

Description

Technical Field

[0001] This invention belongs to the field of food preservation technology and relates to a method for magnetic field-assisted cold storage preservation of shiitake mushrooms. Background Technology

[0002] Shiitake mushrooms, as a major cultivated edible fungus, have become a crucial pillar of the edible fungus industry. As one of the world's leading edible fungi in both production and consumption, they are an important part of people's daily diet due to their unique flavor and rich nutritional content. Fresh shiitake mushrooms are difficult to store after harvesting; their high water absorption and susceptibility to oxidation lead to mold and spoilage. Currently, there are insufficient reports on the systematic application of magnetic field technology alone to the cold storage and preservation of shiitake mushrooms. Therefore, developing a safe, efficient, and chemical-preservative-free magnetic field-assisted cold storage method is of great significance for extending the shelf life of shiitake mushrooms and maintaining their nutritional value and commercial quality. Summary of the Invention

[0003] To address the above problems, this invention provides a method for magnetic field-assisted cold storage and preservation of shiitake mushrooms, specifically including the following steps:

[0004] Step 1: Select freshly picked shiitake mushrooms, remove softened or cracked fruiting bodies, and keep fresh shiitake mushroom fruiting bodies that are firm, intact, and free of mold. Remove dust, impurities, and stem parts from the surface.

[0005] Preferably, the shiitake mushrooms are 80-90% mature.

[0006] Step 2: Cold treatment to lower the temperature of shiitake mushroom fruiting bodies to 0-10℃, then package them and store them in a static magnetic field at 3.5-4.5℃, 80%RH, and 3-9mT, with the magnetic field direction along the Y-axis.

[0007] Preferably, the magnetic field uniformity is >90%.

[0008] Preferably, the cold treatment involves refrigerating the fruiting bodies of shiitake mushrooms at 4°C for 1 hour.

[0009] Preferably, the packaging operation involves packaging the shiitake mushrooms into self-sealing bags with ventilation holes. Most preferably, the self-sealing bags are made of food-grade polyethylene material.

[0010] The present invention has the following beneficial effects:

[0011] This invention significantly inhibits postharvest physiological metabolism in shiitake mushrooms simply by controlling magnetic field conditions and a low-temperature, high-humidity environment, without any chemical preservatives. This method effectively reduces the weight loss rate of shiitake mushrooms, better maintains their original color, firmness, and cell membrane integrity (reflected by electrical conductivity), and simultaneously inhibits lignin accumulation related to tissue lignification and chitinase activity related to cell wall degradation. This delays senescence, browning, and softening of shiitake mushrooms, significantly extends their cold storage shelf life, maintains excellent commercial and edible quality, and the entire process is safe, environmentally friendly, and residue-free. Detailed Implementation

[0012] The technical solutions in the embodiments of the invention are described clearly and completely below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0013] The following are the calculation methods for the various indicators in the embodiments and comparative examples:

[0014] Weight loss rate determination method: The determination method was carried out in accordance with the method in "The Influence of Different Modified Atmosphere Packaging on the Preservation Effect of Bracken Fern" (Modern Food Science and Technology, 2019, Issue 04). The formula for calculating the weight loss rate is as follows:

[0015] ω = (m1 - m2) / m1 × 100%.

[0016] In the formula: ω is the weight loss rate, m1 is the mass of the sample before storage, and m2 is the mass of the sample after storage.

[0017] Method for determining color difference: Randomly select 5 shiitake mushrooms, and randomly select 3 points on the cap to measure the L* (brightness), a* (redness-greenness), and b* (yellowness-blueness) values ​​of the shiitake mushrooms using a colorimeter. Calculate the chromaticity coordinate x, and substitute x into the following formula to calculate the browning index of the shiitake mushrooms:

[0018] Browning index = [100(x-0.31)] / 0.172.

[0019] x=(a*+1.75L*) / (5.645L*+a*-3.012b*).

[0020] Method for determining hardness: The puncture force of the shiitake mushroom cap was measured using a texture analyzer to characterize the tissue hardness.

[0021] Method for determining relative conductivity: The conductivity change of shiitake mushroom tissue extract was measured using a conductivity meter.

[0022] Example 1

[0023] Step 1: Select freshly picked shiitake mushrooms, remove softened and cracked fruiting bodies, and retain fresh shiitake mushroom fruiting bodies that are firm, intact, and free of mold. Remove surface dust, impurities, and stem parts. Pre-cool the shiitake mushroom fruiting bodies in a refrigerator at 4°C for 1 hour. Pack the shiitake mushrooms into food-grade polyethylene self-sealing bags with ventilation holes and store them in a static magnetic field at 4±0.5°C, 80%RH, and 3mT, with the magnetic field direction along the Y-axis and a magnetic field uniformity >90%.

[0024] After 15 days of continuous storage, the extracted shiitake mushrooms retained the original flavor of shiitake mushrooms, but their color differed significantly from the initial shiitake mushrooms. The weight loss rate was 6.5±0.8%, the browning index was 81.99±3, the firmness was 11.4±1, and the electrical conductivity was 37.7±4%. The mushrooms exhibited moderate browning, with the gills darkening and softening, showing initial signs of softening. They also had a slight odor, indicating that the preservation effect was average.

[0025] Example 2

[0026] The difference from Example 1 is that the magnetic field strength is 6 mT.

[0027] After 15 days of continuous storage, the extracted shiitake mushrooms retained their original flavor, but their color differed significantly from the initial mushrooms. The weight loss rate was 6.6±1.8%, the browning index was 75.16±3, the firmness was 13.6±0.6, and the electrical conductivity was 29.7±0.5%. They showed slight browning, with the gills becoming slightly darker and softer, and a slight odor. The preservation effect was good.

[0028] Example 3

[0029] The difference from Example 1 is that the magnetic field strength is 9 mT.

[0030] After 15 days of continuous storage, the extracted shiitake mushrooms retained their original flavor, but their color differed significantly from the initial shiitake mushrooms. The weight loss rate was 7.0±0.6%, the browning index was 83.9±5, the hardness was 10.2±0.8, and the electrical conductivity was 38.9±5%. The mushrooms exhibited moderate browning, with the gills becoming darker and softer, and a rotten odor. The preservation effect was generally poor.

[0031] Comparative Example 1

[0032] Unlike Example 1, the shiitake mushroom samples were treated with refrigeration without applying a magnetic field. The results showed that at the end of the 15-day storage period, the surface became sticky and the quality of the shiitake mushroom samples decreased compared with the initial storage conditions. The weight loss rate was 8.1±0.4%, the browning index was 86.2±1, the hardness was 9.3±1, the electrical conductivity was 43.5±0.4%, and there was severe browning, rotten gills, softness, water stains, and a strong odor.

[0033] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for magnetic field-assisted cold storage and preservation of shiitake mushrooms, characterized in that, The pretreated shiitake mushroom fruiting bodies were stored in a static magnetic field of 3.5-4.5℃, 80%RH, and 3-9mT, with the magnetic field direction being the Y-axis and the magnetic field uniformity being >90%.

2. The method for magnetic field-assisted cold storage and preservation of shiitake mushrooms according to claim 1, characterized in that, The pretreatment method for shiitake mushroom fruiting bodies includes pre-cooling and packaging shiitake mushroom fruiting bodies obtained by screening fresh shiitake mushrooms.

3. The method for magnetic field-assisted cold storage and preservation of shiitake mushrooms according to claim 2, characterized in that, The specific steps for selecting fresh shiitake mushrooms to obtain shiitake fruiting bodies are as follows: remove softened or cracked fruiting bodies from fresh shiitake mushrooms, retaining fresh shiitake mushroom fruiting bodies that are firm, intact in appearance, and free from mold, and remove surface dust, impurities, and the root stem.

4. The method for magnetic field-assisted cold storage and preservation of shiitake mushrooms according to claim 3, characterized in that, The shiitake mushrooms are 80-90% mature.

5. The method for magnetic field-assisted cold storage and preservation of shiitake mushrooms according to claim 2, characterized in that, The pre-cooling process involves refrigerating the shiitake mushroom fruiting bodies at 4°C for 1 hour.

6. The method for magnetic field-assisted cold storage and preservation of shiitake mushrooms according to claim 2, characterized in that, The packaging operation involves packaging the shiitake mushrooms into resealable bags with ventilation holes.

7. The method for magnetic field-assisted cold storage and preservation of shiitake mushrooms according to claim 6, characterized in that, The self-sealing bag is made of food-grade polyethylene material.