Key Technical Points for Low-Temperature Fresh-Keeping and Processing of Edible Fungi

In the chain of large-scale industrialized production of edible fungi, the fresh-keeping and processing of edible fungi is an important organizational link. It is not only an indispensable link in production, circulation and consumption, but also the foundation for expanding reproduction and increasing benefits for the industrialization of edible fungi. In traditional fresh mushroom sales, bamboo or plastic turnover boxes are generally used as containers. The harvested fresh mushrooms are placed directly into the boxes and then enter the market. The fruiting bodies are piled up and bumped inside the boxes, greatly reducing their commercial quality, and they are directly exposed to sunlight or the atmosphere, passively accepting contamination while also being unfavorable for fresh-keeping. Consumers also report being unable to buy fresh, plump mushrooms. This is the first point. Second, with economic development and the accelerating pace of people's lives, quite a number of consumers have neither the time nor the mood to go to crowded farmers' markets to select mushrooms. Instead, they hope for convenient, clean, small-packaged products that can be cooked shortly after returning home, so supermarket sales have emerged. It is understood that supermarkets in major southern cities have sold small-packaged fresh mushrooms for several years, with quite good market results. At present, supermarkets in the north have also taken action, showing that this is a development trend.

The basic procedure is: fresh mushroom harvesting -> low-temperature sorting -> cooling and packaging -> boxed transport -> entering supermarkets. Once fresh mushrooms are harvested, they must be neatly arranged in small, low containers and sent as quickly as possible to a low-temperature workshop for sorting. The container volume is length x width x height = (40 x 28 x 16) cm. Its shape is like a turnover box, with a solid bottom plate, round holes about 2--3 cm in diameter preset around the sides, and inward-retracted interlocking corner blocks at all four bottom corners, so as to facilitate stacking in multiple layers. When harvesting fresh mushrooms, they should be placed in the same direction, not head-to-tail, to avoid contamination; the temperature in the low-temperature workshop is 1--3°C. An ordinary constant-temperature cold storage room can be modified for use, and together with other packaging containers, all should be stored in the workshop so as to be thoroughly cooled. After fresh mushrooms are moved into the workshop in boxes, they should be placed separately and must not be stacked in multiple layers again, so that the mushroom bodies can be fully cooled. This step is especially important for fresh mushrooms harvested when the temperature is above 15°C. The sorting tools are: a thin stainless steel knife or bamboo blade knife, as well as small-package sealing, boxing and other equipment.

First use a small knife to trim the base of the fresh mushrooms clean, removing all soil, substrate and other debris. If there are many scales, they should also be removed. Generally, do not wash with water, otherwise the shelf life of the product will be shortened. Then immediately grade the clean fresh mushrooms and place them in containers lined with soft foam material. After they are fully cooled, package them.

Cooling and packaging: after the interior of the mushroom bodies has cooled to below 3°C, they can be sub-packaged. Generally, foam lunch-box-style containers can be used, made into single boxes about 5 cm high, each containing about 150 grams of fresh mushrooms. Some large cities have already banned the sale of plastic packaging, so custom paper boxes can be used. The specifications of the packaging boxes can also be determined according to the variety of fresh mushrooms. For example, shaggy ink cap mushrooms are generally suitable for packaging of 16 cm x 10 cm x 4 cm specifications (length x width x height, the same below), Agaricus blazei is suitable for 15 x 10 x 6 specifications, and Hypsizygus marmoreus, willow mushroom, etc. are suitable for 16 x 8 x 4 specifications. The arrangement method is also determined according to the morphology and size specifications of the fresh mushrooms. Then seal the package with cling film. Put the small packaging boxes into foam fresh-keeping boxes, each box can hold 36 boxes, and seal with transparent tape. Boxed transport: according to the transport distance and means of transport, etc., the fresh-keeping boxes can be transported directly, or loaded into containers for shipment. Because the insulation effect of the fresh-keeping box is extremely good, and the boxed packaging inside has also undergone low-temperature treatment, there will be no quality degradation of fresh mushrooms due to temperature rise within 5-12 hours: among them, shaggy ink cap mushrooms and straw mushrooms are the most difficult to keep fresh, but within 5 hours there will also be no quality degradation problem.

Entering supermarkets: after entering supermarkets, the small packages should be placed in low-temperature display cabinets for sale. Generally, the shelf life can reach 2-10 days.

In addition, for short-term storage and transport, methods such as rapid ice cooling for fresh-keeping or refrigerated truck transport can also be used. Generally, mushrooms should be controlled at a refrigerated temperature of 1--3°C. After long-distance transport, the mushroom bodies maintain their original color and shape unchanged, and the effect is relatively good.