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6 Carrageenans
In milk preservation, the three types of carrageenans, λ, κ and ι, are usually
mixed together. Carrageenan is usually used in concentration ranging between 0.01
and 0.05 wt% (Towle 1973; Syrbe et al. 1998; Tijssen et al. 2007). Carrageenan is
particularly of importance in ultrahigh temperature (UHT) treated milk in which the
milk protein has been slightly denatured due to high-temperature treatment.
Carrageenan stabilizes milk by forming a secondary helical structure and then
bridges forming at different junctions of the helices. The κ- and ι-type carrageenans
usually form these helical secondary structures resulting in gelation. Gelation is
affected by the presence of certain ions, particularly calcium (Ca+) ions and potassium (K+) ions. The high amount of sulfate groups present in the λ-type carrageenan
prevents it from gelation. This gelation is then further combined with complexation
which occurs as a result of electrostatic interactions between the carrageenan and
the protein. This is a result of the positive charged regions on the surface of the milk
protein and the sulfate groups of the carrageenan. In some cases, this may be further
aided by cations such as Ca+ forming bridges between the carboxyl group of the
proteins and the sulfate groups of carrageenan (Tijssen et al. 2007).
Carrageenan is also used in other dairy products such as cheese, ice creams,
chocolate milk and coffee creamers for the separation of whey and fat. 33% of the
carrageenan market is from use in dairy products (McHugh 2003). This makes up
the market where much of carrageenan is used.
6.7.2 Gelling Agent
In the presence of electrolytes such as rubidium, potassium and cesium, kappa carrageenan can form gels at much lower concentration (Williams and Phillips 2003).
Such that, less carrageenan is required to obtain the required gel texture. This is
important for both reducing cost of food processing and also minimizing the additive content. Hence why, kappa form of carrageenan is much preferred as a gelling
agent compared to other forms. Gels formed in the presence of potassium chloride
(KCl) show superior gel strength (William and Phillips). Iota carrageenan does not
show this same increased gel strength in the presence of potassium chloride. Although
kappa forms strong gels, they are rather brittle and more prone to syneresis in the
absence of enhancers. Konjac mannan and locust bean gum are used to improve the
gel properties and prevent syneresis (Williams and Phillips 2003).
In water-based jelly, a combination of kappa and iota carrageenan can be used as
a replacement for pectin where a little or no calorie alternative is needed. In nondairy
alternatives to ice cream such as sorbet, the creamy mouthfeel is achieved using a
mixture of iota and kappa carrageenan. For this purpose, locust bean or pectin is also
added to enhance the texture. A mixture of kappa and iota carrageenan is also used in
stabilizing oil in water emulsions in mayonnaise with reduced oil content. Xanthan
gum is also added here to aid the activity of carrageenan (McHugh 2003).
6 Carrageenans
In milk preservation, the three types of carrageenans, λ, κ and ι, are usually
mixed together. Carrageenan is usually used in concentration ranging between 0.01
and 0.05 wt% (Towle 1973; Syrbe et al. 1998; Tijssen et al. 2007). Carrageenan is
particularly of importance in ultrahigh temperature (UHT) treated milk in which the
milk protein has been slightly denatured due to high-temperature treatment.
Carrageenan stabilizes milk by forming a secondary helical structure and then
bridges forming at different junctions of the helices. The κ- and ι-type carrageenans
usually form these helical secondary structures resulting in gelation. Gelation is
affected by the presence of certain ions, particularly calcium (Ca+) ions and potassium (K+) ions. The high amount of sulfate groups present in the λ-type carrageenan
prevents it from gelation. This gelation is then further combined with complexation
which occurs as a result of electrostatic interactions between the carrageenan and
the protein. This is a result of the positive charged regions on the surface of the milk
protein and the sulfate groups of the carrageenan. In some cases, this may be further
aided by cations such as Ca+ forming bridges between the carboxyl group of the
proteins and the sulfate groups of carrageenan (Tijssen et al. 2007).
Carrageenan is also used in other dairy products such as cheese, ice creams,
chocolate milk and coffee creamers for the separation of whey and fat. 33% of the
carrageenan market is from use in dairy products (McHugh 2003). This makes up
the market where much of carrageenan is used.
6.7.2 Gelling Agent
In the presence of electrolytes such as rubidium, potassium and cesium, kappa carrageenan can form gels at much lower concentration (Williams and Phillips 2003).
Such that, less carrageenan is required to obtain the required gel texture. This is
important for both reducing cost of food processing and also minimizing the additive content. Hence why, kappa form of carrageenan is much preferred as a gelling
agent compared to other forms. Gels formed in the presence of potassium chloride
(KCl) show superior gel strength (William and Phillips). Iota carrageenan does not
show this same increased gel strength in the presence of potassium chloride. Although
kappa forms strong gels, they are rather brittle and more prone to syneresis in the
absence of enhancers. Konjac mannan and locust bean gum are used to improve the
gel properties and prevent syneresis (Williams and Phillips 2003).
In water-based jelly, a combination of kappa and iota carrageenan can be used as
a replacement for pectin where a little or no calorie alternative is needed. In nondairy
alternatives to ice cream such as sorbet, the creamy mouthfeel is achieved using a
mixture of iota and kappa carrageenan. For this purpose, locust bean or pectin is also
added to enhance the texture. A mixture of kappa and iota carrageenan is also used in
stabilizing oil in water emulsions in mayonnaise with reduced oil content. Xanthan
gum is also added here to aid the activity of carrageenan (McHugh 2003).