Manufacture of and uses for low molecular weight agars and agaroids
First Claim
1. A process to manufacture a material able to form an aqueous gel which, at a concentration of 15% of solids by weight has a dynamic gel strength of 0-100 g/cm2, that comprises the sequence of steps of taking an agar or agarose with 0-2 methyl groups per agarobiose unit and which has had the agarobiose content maximised by rigorous alkali treatment such that no increase in gel strength can be achieved by repeated alkali treatment, and dissolving this agar or agarose in water, then partially depolymerizing it by making the pH less than 7 and maintaining temperature between 35-140°
- C. for a period of time chosen to give the appropriate degree of depolymerization for the required final gel strength, then neutralizing the mixture and cooling it so a gel forms, then freezing then thawing the mixture to provide a particulate solid dispersed in the water, then straining the liquid to obtain the said material.
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Accused Products
Abstract
A process is claimed whereby an aqueous solution of agar, in which most (ideally all) 4-linked residues consist of 3,6-anhydro-L-galactose, is subjected to partial acid hydolysis and upon neutralization following the time appropriate for the chosen conditions, a low strength gel is obtained, from which, contrary to expectations, a polyagarobiose can be obtained by freeze-thawing and straining, thereby eliminating undesirable agaroid materials without the appropriate 3,6-anhydrogalactosyl content. The appropriate time of hydrolysis depends on initial gel strength, pH, counterion concentration and temperature. As an example, agar (gel strength 700 g/cm2, made to 1.86% solution) pH 3.25, counterion citrate (360 mg/L) at 96° C. requires 25 minutes to yield a material with an eventual gel stregth (1.5% solution) of 40 g/cm2. A stabilized product can be prepared by reducing terminal anhydrogalactosyl residues with sodium borohydride. The resultant products are useful for preparing gels for application to the skin, such as massage gels, as skin moisturizers, or as carriers of other active ingredients, such as pharmaceuticals able to be applied through the skin.
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Citations
12 Claims
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1. A process to manufacture a material able to form an aqueous gel which, at a concentration of 15% of solids by weight has a dynamic gel strength of 0-100 g/cm2, that comprises the sequence of steps of taking an agar or agarose with 0-2 methyl groups per agarobiose unit and which has had the agarobiose content maximised by rigorous alkali treatment such that no increase in gel strength can be achieved by repeated alkali treatment, and dissolving this agar or agarose in water, then partially depolymerizing it by making the pH less than 7 and maintaining temperature between 35-140°
- C. for a period of time chosen to give the appropriate degree of depolymerization for the required final gel strength, then neutralizing the mixture and cooling it so a gel forms, then freezing then thawing the mixture to provide a particulate solid dispersed in the water, then straining the liquid to obtain the said material.
- View Dependent Claims (4, 6, 7, 8, 9, 10, 11, 12)
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2. A process to manufacture a material able to form an aqueous gel which, at a concentration of 15% of solids by weight has a dynamic gel strength of 0-100 g/cm2, that comprises the sequence of steps of taking an agar or agarose with 0-2 methyl groups per agarobiose unit and which has had the agarobiose content maximised by rigorous alkali treatment such that no increase in gel strength can be achieved by repeated alkali treatment, and dissolving this agar or agarose in water, then partially depolymerizing it by making the pH less than 7 and maintaining temperature between 35-140°
- C. for a period of time chosen to give the appropriate degree of depolymerization for the required final gel strength, then neutralizing the mixture and adding sodium borohydride, neutralizing to pH 7, and cooling the mixture so a gel forms, then freezing then thawing the mixture to provide a particulate solid dispersed in the water, then straining the liquid to obtain the said material.
- View Dependent Claims (3, 5)
Specification