THE STORY OF LAP CHEONG

THE STORY OF LAP CHEONG

Traditional Chinese meat product are famous for their attractive colour, strong aroma, and unique taste. They are part of the precious cultural heritage of China as they symbolize ancient Chinese imagination and creativity in meat processing spanned over a long period of time and space. Chinese sausage is a generic term referring to the many different types of sausages originating in China.

The southern flavor of Chinese sausage is commonly known by its Cantonese name ‘lap cheong’ which means the “winter stuffed intestine” or “waxed intestine” because “cheong” not only means “intestine” but also “sausage”. Chinese sausage is a dried, hard sausage usually made from fatty pork. This sausage is normally smoked, sweetened, and seasoned.

Lap Cheong, a type of sausage from China. (Retrieved from https://commons.wikimedia.org/wiki/File:Chinese_sausages_drying.jpg )

INGREDIENTS IN THE MEAT

Salt

Salt is indispensable in meat processing. Besides its antimicrobial effect, salt improves the flavor of ‘lap cheong’. In the southern part, about 1.5 % of salt is used for ‘lap cheong’ processing, while ~ 30 % of it is used in the northern part of China.

Sodium nitrate and sodium nitrite

Addition of sodium nitrate and sodium nitrite is necessary to inhibit the growth of numerous pathogenic microorganisms in the ‘lap cheong’. Although many options has been explored, sodium nitrate and sodium nitrite remains as the most effective antimicrobial agents in the manufacturing of the traditional Chinese sausages.

Soy sauce

Soy sauce is a common flavouring agent used in making Chinese sausages. Most soy sauces are in the form of brown or black liquids. Soy sauces help maintain the natural colour of the ‘lap cheong’ meats and are normally added at level of 0.8-1.5%.

Liquors

Liquors are used to reduce unpleasant smell and enhance aroma and mellowness of processed meat. The most common liquors used in making Chinese meat products are rice wine, white spirits, and Chinese rose liquor.

EFFECTS OF PROCESSING

The processing steps of Lap Cheong is as shown in flow chart below.

Grinding and mixing

Lean meat is minced using mincers and solid pork fat is diced into 5 – 8 mm cubes and rinsed in water for several minutes to remove impurity and melted fat. Salt, water, diced fat, and other seasoning are then mixed with minced meat using mixer to cure the meat.

Grinding cause easily recognized physical changes in meat that are essentially the same in pre- and post-rigor meat. Grinding accelerates a number of biochemical processes, including oxidation of the lipids and glycolysis in pre-rigor muscle. Besides, grinding also increase the surface area, improves the water binding capacity. Meanwhile, the most obvious change occurring during curing of meat is related to colour. The myoglobin reacts with nitrite to produce a stable pink pigment known as nitric oxide myoglobin. Brown colour metmyoglobin will forms if without presence of nitrite. The addition of salt does alter the water holding capacity of the meat. Lowering of water activity (a_w) by curing is largely responsible for the stable nature of cured meat, since low a_w values inhibit microbial growth and meat spoilage.

Stuffing

Stuffing is usually done manually and by means of very simple fillers. The sausages are linked with pieces of straw (traditional Chinese method) or both ends are tied into 10 or 15 cm links with light twine. immediately after stuffing the sausages are densely perforated on all sides for the escape of entrapped air and also water vapour during the next stage of drying and smoking.

Chinese sausages linked with pieces of straw prior to smoking. (Retrieved from http://www.fao.org/docrep/003/x6556e/x6556e06.htm)

Drying and smoking.

This is the most important operation in Chinese sausage manufacture. The most suitable type of drying room or smokehouse for Chinese-style sausages is usually an especially designed brick-built unit with very simple installations. In drying Chinese sausages, the main aim is a constant and uniform supply of heat (and smoke, if desired) to produce a uniformly dry product. Maintenance of good air circulation is essential and the sausages must be hung in a well-spaced manner on racks in the smokehouse. Drying is done at 48–50°C for 72 hours.

Thermal treatment during meat processing will cause physical and biochemical changes as proteins in meat has been strongly influenced. Changes in protein composition and functional properties during processing play important roles in the textural, sensory and nutritional quality of meat products. As processing time proceeded, changes in the protein composition of Cantonese sausage were illustrated by the progressive decrease in sarcoplasmic (water-soluble protein fraction) and myofibrillar (salt-soluble protein fraction) protein fractions, accompanied by an increase in the alkali-soluble and non-protein fractions. The quality of meat product, which is mainly governed by protein functional characteristics, is also changed drastically during processing.

Oxidation can lead to the polymerization and aggregation of proteins. Moreover, oxidation can also alter the secondary and tertiary structures of proteins, leading to changes in physical properties of proteins, such as solubility and hydrophobicity. The decrease of average particle size of Cantonese sausage proteins at the early stage might be due to the proteolysis of Cantonese sausage, which involves in the decrease of high molecular-weight proteins and formation of polypeptides and free amino acids.

Chilling and “sweating” process

The sausages are removed from the smokehouse and placed in a well-ventilated room for chilling. The changes occur during chilling process would be cold shortening. Cold shortening appears to be related to the inability of the sarcoplasmic reticulum to sequester and bind excess Ca ²⁺ ions released from the sarcoplasmic reticulum and mitochondria under the influence of cold temperature and declining pH values in pre-rigor muscle. They are then either stored in bins or in cardboard cartons to undergo the “sweating” process.

Summary

            Changes occurring during processing of ‘lap cheong’ can be either physical or biochemical. It is possible that both types of changes are involved. Physical changes include colour alteration and coagulation of the protein that occur during cooking. Processing also causes changes in the colour of meat as the myoglobin reacts to produce the characteristics pink pigment observed in cured meats. While chilling induced cold shortening which results in excessive shortening and toughening of meat.

Did you know?

Lap Cheong may be cooked and eaten on their own, but also works well with rice and vegetables and can be used as an ingredient in other dishes, such as fried rice dishes and glutinous rice parcels. Lap Cheong can be easily cooked alongside rice by adding it on top of the steaming rice, either using a metal dish stand, or directly onto the partially-cooked rice.

Steamed Lap Cheong rice. (Retrieved from http://www.thehongkongcookery.com/2014/12/steamed-lap-cheong-rice.html )