Experiment on processing Technology of canned Pleurotus ostreatus

Pleurotus ostreatus is one of the main varieties of edible fungi, which belongs to Pleurotus ostreatus, Pleurotus ostreatus and Pleurotus ostreatus in taxonomy. The cultivation technology of Pleurotus ostreatus is simple, the technical difficulty is relatively small, and the cultivation raw materials are extensive, which make it the artificial cultivated variety with the highest yield and the largest sales in the domestic edible mushroom market. It is widely cultivated in our country, especially in the north. In some provinces and cities, it has become the pillar industry of local agriculture, and many farmers in poor areas have embarked on the road of getting rich by cultivating Pleurotus ostreatus. It is not difficult to predict that with the expansion of international and domestic markets, the improvement of people's diet structure and consumption level in urban and rural areas, Pleurotus ostreatus, as the main species of edible fungi, will certainly get greater development. Pleurotus ostreatus has high nutritional value and health care function, its fresh products are rich in amino acids and B vitamins, vitamin C and ergosterol are also high. In addition, the application of Pleurotus ostreatus polysaccharides and polysaccharide proteins in cancer prevention and anticancer has also been reported. Pleurotus ostreatus is mainly fresh food, and part of it is used for salinization processing and export. Because the fruiting body of Pleurotus ostreatus is delicate, the water content is high, and the postharvest respiration is very strong, it is easy to deteriorate. If stored at room temperature above 16 ℃ for 1 day, there will be long white hair on the stalk, cracking and crimping of the umbrella cover, until browning and decay. At the same time, Pleurotus ostreatus has large surface area, strong transpiration and easy to lose water, which leads to the decrease of freshness and affects the flavor and commodity value. Therefore, the quality of fresh Pleurotus ostreatus is difficult to control. Canned Pleurotus ostreatus is safe, convenient and hygienic, can be preserved at room temperature for a long time, and its quality is stable, so it is in great demand at home and abroad.

1 test materials and methods

1.1 Test materials

Salted Pleurotus ostreatus is provided by the local factory, while salt and citric acid are purchased from the local market.

1.2 Test instruments and equipment

Sandwich pot, GT4B2 vacuum sealing machine, steam pressure sterilization pot and so on.

1.3 Test methods

The process route of processing canned Pleurotus ostreatus is as follows: raw material → desalting → washing → pre-cooking → selecting → cleaning → canned → filling soup → sealing → sterilization → cooling → heat preservation → inspection of → products.

1.3.1 because fresh Pleurotus ostreatus is easy to deteriorate and its quality is difficult to control, salted Pleurotus ostreatus is used as raw material. It is appropriate to choose varieties with short stalk, thick meat, not easy to break and suitable for canning processing, such as Pleurotus ostreatus, Pleurotus ostreatus and so on. The raw material quality standard is brine concentration 18 °be'~ 22 °be', Pleurotus ostreatus has no peculiar smell, mildew, disease, insect and mud sand impurities, no surface yellowing, stickiness, shrinkage and deterioration, the stalk length does not exceed 1.5cm, and the fragmentation rate does not exceed 5%.

1.3.2 soak the raw materials into the soaking pool and wash and desalinate with flowing water until the salt content of Pleurotus ostreatus is less than 0.3%.

1.3.3 blanching desalted Pleurotus ostreatus 2min~3min in boiling water, cool immediately.

1.3.4 pick and remove impurities and crumbs of Pleurotus ostreatus and grade them according to the size of the cap. The diameter of the cap of the first class Pleurotus ostreatus is 5cm~8cm, the diameter of the second class Pleurotus ostreatus is 2cm~5cm, and the mixed products account for 50% and 50% respectively.

1.3.5 the mass fraction of salt water in soup juice is 2.2%-2.5%, boil 2min~3min, and add 0.05% citric acid to boiling salt water, filter and set aside. The temperature of salt water is not lower than 90 ℃.

1.3.6 the choice of can type is 7116. After cleaning the empty can, it was sterilized by hot water over 85 ℃, then drained and canned. The amount of each can of Pleurotus ostreatus was 195g. The tissue shape of the cover is required to be complete, and the color, size and stalk length of Pleurotus ostreatus in the same pot are uniform. Add the soup after filling the mushrooms, and add each can of soup to 1cm away from the mouth of the can.

1.3.7 the vacuum degree of the vacuum sealing machine is 40kPa~53kPa, and the central temperature of the tank is not less than 85 ℃.

1.3.8 the germicidal formula is 20ml / 20mm-reverse pressure cooling / 121℃. The time from sealing to sterilization does not exceed 30min. After sterilization, it was quickly cooled to below 37 ℃.

1.3.9 enter the storage to clean the surface of the tank and put it into the heat preservation warehouse in time.

2 product quality requirements and test results

2.1 Product quality requirements

2.1.1 sensory indicators: the color is light yellow, the soup is clear, and a small amount of crumbs of Pleurotus ostreatus is allowed; it has the taste of canned Pleurotus ostreatus, without peculiar smell; the tissue shape of the cap is complete, uniform in size and slightly elastic.

2.1.2 the physical and chemical index product specification is 425g net mass, and its physical and chemical index is shown in Table 1.

Table 1 physical and chemical indexes of canned Pleurotus ostreatus

Test items | Standard requirements | Test results |

Net mass g | allowable tolerance per can 3% | 430 |

Solids g | not less than 52% of net mass | 235 |

Sodium chloride content% | 0.8-1.5 | 1.00 |

Copper mg/kg | ≤ 10 | 0.30 |

Tin mg/kg | ≤ 200 | 0.01 |

Lead mg/kg | ≤ 1 | 0.10 |

2.1.3 the total number of bacteria was not more than 10 / mL; and the coliform group was less than 6 / mL;. No pathogenic bacteria were detected.

3 Analysis of nutritional components of canned Pleurotus ostreatus

After the products were stored at room temperature for 3 months, the nutritional components of the products were detected. The results showed that there were 89.02g moisture, 3.84g protein, 0.46g fat, 4.58g carbohydrate, 1.10g fiber and 2.10g ash per 100g canned Pleurotus ostreatus.

4 points for attention

The main results are as follows: (1) canned Pleurotus ostreatus is a low-acid food, if the raw materials are contaminated or not sterilized thoroughly, it is easy to cause rancidity and deterioration of the contents, which is caused by the reproduction of thermophilic acidophilic bacteria (flat acid bacteria) in the tank. Therefore, in production, we should strictly abide by the process operation rules, strengthen hygiene management, and strictly control the sealing quality of cans. In addition, the number of thermophilic acidophilic spores of raw materials, semi-finished products and canned products before sterilization after sealing should be tested frequently to guide and monitor the production process.

(2) in production, the operation process should be shortened as much as possible, and the exposure time of raw materials should be reduced so as to avoid pollution caused by the backlog of semi-finished products.

(3) to prevent the raw materials of Pleurotus ostreatus from coming into contact with iron, copper and other metal tools, the processing utensils and operating tables had better be made of stainless steel.

(4) in addition to tinplate cans, the packaging containers can also be packaged in spiral glass bottles and cooking bags.