Winter is the season for collecting and processing pork casings. Processors should select raw pork intestines that are fresh in color, have a normal odor, are intact at both ends (with both large and small ends present), free from breaks or wounds, over 14 meters in length per intestine, and uncontaminated by mud or sand. Only such intestines can be used to produce excellent sausages. Below are two methods for producing casings:

1. Method for Producing Salted Casings

• Immersion and Rinsing: After removing fecal matter, immerse the small intestines in water. Flush the inside with clean water at approximately 20°C and soak in fresh water for 24 hours.

• Scraping: After soaking, remove the intestines and use a bamboo scraper to remove excess tissue from both the inside and outside. Scrape off the inner mucosal layer to obtain a transparent membrane, taking care to avoid puncturing it.

• Flushing: Insert a water faucet into one end of the intestine and flush. If any holes or ulcers are found, cut them out, then rinse clean.

• Gauging and Bundling: After flushing, bundle the casings at 100 yards (approx. 91.5 meters) per hank, with a length tolerance not exceeding 1 meter. Each hank should contain no more than 16 pieces (ends), with each piece being no shorter than 2 meters.

• Salting and Hanking: For the bundled casings, first separate all the knots. Sprinkle an appropriate amount of salt evenly, then place the casings on screens. Stack the screens on racks to drain the water. Cover the top and sides of the screens with white cloth. When hanking, strive for consistent color within each hank; remove any discolored sections. Untie any knots. After salting for 12-13 hours, when the inside of the casing is semi-dry, they can be hanked. This produces the semi-finished product known as "rough casings" or "light casings".

• Soaking and Washing: Immerse the "light casings" in fresh water, changing the water repeatedly and washing thoroughly to ensure all impurities inside and outside the casings are removed. The water temperature for soaking should not be too high.

• Sorting and Salting: Fill the "light casings" with water to check for leaks. Then, sort and tie them into small hanks according to their diameter (caliber) and length. Subsequently, salt them with refined salt. After the water drains away, hank them again. This results in the finished product known as "clean casings".

2. Method for Producing Dried Casings

• Immersion and Rinsing: Immerse the thoroughly cleaned small intestines in fresh water for several hours, or for 1-2 days in winter.

• Fat Removal: Place the soaked fresh intestines on a wooden board and remove the fat, serous membrane, and fascia from the outside of the intestinal tube. Then, bundle the fresh intestines into sets of 10 tubes each. Place them in a vat, adding 2500 ml of a 5% sodium hydroxide solution for every 7-8 sets. Quickly stir the intestines to wash away the fat.

• Rinsing: Transfer the degreased intestines to a vat of fresh water. Change the water repeatedly to rinse away blood, residual fat, and the smell of sodium hydroxide.

• Salting: Use 0.75 - 1 kg of salt per 100 yards (approx. 91.5 meters). Salt the casings for 12-24 hours, then remove and rinse with water, striving to remove all salt residue as much as possible.

• Inflation: Use an air pump to inflate the cleaned casings, causing them to expand. Then, place them in clean water to check for leaks. Hang the inflated casings in a well-ventilated area to dry.

• Flattening and Packing: Once dry, puncture one end of the casing with a needle to release the air. Spray water evenly to slightly moisten them, then flatten the casings. Bundle and tie them into hanks, after which they can be packed into boxes.