How is traditional salted duck modernized in processing?

Salted duck is the duck meat delicacy most loved by people in the Jiangsu-Zhejiang region of China. In recent years, it has gradually spread to all parts of the country. Traditional salted duck has a rather salty taste. When salted duck was first developed, one purpose was to give the duck meat a certain flavor, but the main purpose was still to use salt for preservation, so traditional salted duck has a relatively high salt content. Furthermore, the traditional processing method has a long production cycle, is workshop-style production, has poor sanitary conditions, and lacks standardized and unified criteria, so it cannot guarantee the stability of product quality, nor is it convenient for large-scale industrial production, whereas the modern processing of salted duck is different.

1. Process flow

Raw material selection -> pretreatment -> curing -> boiling -> vacuum packaging -> sterilization -> heat preservation test -> outer packaging -> finished product.

2. Key operation points

(1) Raw material selection and handling. Select healthy fat ducks of the current year. After slaughtering and plucking, cut off the second joint of the wings and the feet, then make an opening under the right wing, take out all the internal organs, rinse the inside and outside of the carcass with clean water, then soak in cold water for about 1 h. After taking it out, soak it in a 10% mass fraction food-grade trisodium phosphate (TSP) solution for 15 s (temperature below 13°C), then hang it to dry for 1 h to 2 h until ready for use.

(2) Curing. ① Use the dry curing method. Rub salt fried with star anise onto the inner cavity and surface of the duck body. For each duck (about 2 kg), the salt amount used is 100 g to 150 g. After rubbing, stack and cure. Note that when rubbing salt, the salt on the body surface and in the cavity should be dissolved and then rubbed again, and attention should be paid to rubbing evenly at the cut, head, mouth and the crevices between the thighs. During curing, pay attention to draining the brine. The curing temperature is 0°C to 4°C, and the time is about 24 h (depending on whether the duck is fat or lean). A well-cured duck body has a white surface and feels firm when pressed with fingers, with almost no blood seeping out. ② Mixed curing method. First use dry curing (method as above) for 12 h to 18 h, then perform re-brining (wet curing) for 2 h to 3 h. ③ Preparation of brine. Use the blood water from soaking the duck cavity and add salt to make saturated brine, then add ginger, scallion, star anise and other spices and boil. After boiling, skim off the blood foam and impurities on the water surface, and keep it boiling for 5 min to 10 min. After clarifying, pour it into a sterilized vat and cool for later use. Used brine can be reused repeatedly, and the older the better, but after each use it must be boiled to sterilize, and an appropriate amount of salt and spices must be added according to the situation to ensure the brine is clear and richly fragrant. When the brine is turbid, deteriorated or has changed flavor, it must be prepared anew.

(3) Boiling. Mainly add scallion, ginger, star anise and other seasonings to the water. If the dry curing method is used, an appropriate amount of salt may be added to the water; if the mixed curing method is used, no salt is needed. After the water boils, put the duck into the pot. Boiling water will quickly enter the inner cavity. Lift the duck head to release the hot water in the cavity, then put the duck into the pot again to let the hot water enter the cavity again, and put the duck embryos into the pot one by one in this way. Press on a bamboo cover so that the ducks are fully immersed below the liquid surface, and simmer for about 20 min. At this time, the water temperature in the pot is about 85°C. After 20 min, heat and raise the temperature until the water is almost but not fully boiling, lift the duck and pour out the broth, then put it into the pot again and simmer for about 30 min. When heating is raised for the second time to 90°C to 95°C, lift the duck again and pour the hot broth over it again, then simmer for about 10 min, and it can be taken out of the pot. When taking it out of the pot, care should be taken to protect the outer skin, mouth, wings and other parts of the duck body to ensure the finished product has a good appearance.

(4) Packaging and sterilization. After the ducks taken out of the pot are spread out and cooled in a sterile room for a few minutes, vacuum packaging begins, followed by secondary sterilization. For the sterilization method, use a water bath at 80°C to 85°C for 30 min, sterilize twice, with rapid cooling in between; a microwave sterilization method may also be used, with a power of 900 W for 2 min.

(5) Heat preservation test. Place the sterilized product (take typical samples) into a 36°C constant-temperature incubator for cultivation, and test its bag-swelling rate. If the bag-swelling rate is lower than 5%, proceed with outer packaging, warehousing and sale. If the bag-swelling rate is higher than 5%, then according to the test results of other indicators, analyze the problem and take corresponding measures such as secondary sterilization or reprocessing to ensure the product is hygienic and safe.

3. Points for attention

The characteristics of salted duck should be delicate fragrance, crisp and tender, with a slight salty taste. During processing, brine preparation, curing time, boiling method and temperature control are all extremely important key links. These will directly affect the flavor and texture of the product and should be strictly controlled. In particular, in the boiling process, during simmering the water must not boil and should always be maintained at about 85°C; otherwise, if the water boils, the meat will split, the fat in the meat will melt, the meat quality will become tough, and it will lose its fresh and tender characteristics.