沙菜(卡拉)胶的研究(Ⅳ)——碱处理引起的“SO_4^(2-)含量”变化及对产品质量的影响

Study on Hypnea Gel(Carrageenan)(Ⅳ)

碱处理会引起沙菜(卡拉)胶分子链遭受破坏,而且,去掉一部分“硫酸根”,促使卡拉胶分子由类λ型转变为类κ型。分子链由长变短将增大卡拉胶的水溶性,造成得胶率降低;“硫酸根含量”减少,将导致凝胶强度及胶液粘度提高。此外,碱处理有利于除去色素,使产品更加洁白。采用(含5％KCl)碱浓度为5——10％(重量)的NaOH溶液,对沙菜进行处理,可得到色泽好,“硫酸根含量”约8％,凝胶强度400g/cm^2以上的产品。

As we found that the basic treatment of hypnea gel (carrageenan)will damage its molecular chain, can remove a part of sulfate radical and can result in the transformation of gel molecules from analogous λ type to analogous κ type. The change of the molecular chain from long to short will increase aqueous solvability of hypnea gel, resulting in decrease of-gel productivity. The decrease of sulfate radical content will increase gel strength and liquid gel viscosity. However, the basic treatment is beneficial to the removal of some pigment, and the product becomes even whiter after the basic treatment. A product of good colour and lustre with sulfate radical content of about 8% and gel strength of over 400g/cm^2 can be obtained by treating hypnea with a solution containing 5——10% (w/w) NaOH and 5% KCl.