Curdlan - Ingredient in Meat Products

Curdlan is a linear homopolymer of d-glucose with β-(1, 3) glucosidic linkages ( Fig. 3.9 ), and is produced commercially from the fermentation of glucose by the bacterium Alcaligenes faecalis var. myxogenes (Harada, Masada, Fugimori, & Maeda, 1966) . Curdlan is capable of forming gels with characteristics determined by the temperature to which it is heated. When heated to 60°C, curdlan forms a heat-reversible gel. When heated to 80°C, curdlan forms a heat-stable gel. At 60°C, crosslinking within the gel network is structured with hydrogen bonding, whereas hydrophobic bonding is responsible for crosslinking when heated to 80°C (Konno et al., 1994) . Although reportedly being used in Japan as an ingredient in various types of processed foods, including processed meats (Harada, Terasaki, & Harada, 1993 ; Miwa, Nakao, & Nara, 1994 ; Nakao et al., 1991) , it has not found wide use in other areas of the world.

B Funami, Yotsuzuka, Yada, and Nakao (1998 b) found that nonfat pork sausages containing curdlan had textural properties similar to those of a control 20% fat control. These properties were even closer when the sausages were reheated. Funami et al. (1998 b) also observed that the temperatures normally used in meat processing (≤75°C) allowed for the formation of heat-stable curdlan gels. As with most gelling hydrocolloids, more crosslinking results in stronger gels, resulting in increased syneresis. This is also true with curdlan. The addition of starch to curdlan will help reduce syneresis (Nakao et al., 1991) . 

Prehydrating curdlan is more effective than adding it to the meat in dry form. Funami, Yada, and Nakao (1998 a) reported that the addition to meat of 1% prehydrated curdlan was more effective than the addition of 2% dry curdlan. The authors suggest a more complete gel is formed when the curdlan is prehydrated and this allows for the gel to surround the meat. This is also true of other hydrocolloids as well.

Regulatory Status

In the United States, curdlan is approved by the FDA in foods as a formulation aid, processing aid, stabilizer, thickener, or texturizer. It is not currently approved for use in standardized meat and poultry products but can be used in nonstandardized products. At the time of this writing, curdlan has not been recognized as an approved food additive by the European Commission.