THY+Gums+and+Stabilizers

From the article ‘Formulation Tips on Hydrocolloids’ Freeze thaw stability is the ability of a product to maintain its composition and integrity after repeated cycles between freezing and ambient temperature levels. Even minor temperature fluctuations can cause slight thawing of liquids within a product. Those ice crystals freeze at a larger size, causing the break-down of a product's structure. Gels that may be frozen and thawed repeatedly are called freeze-thaw stable. Many gels begin to degrade after freezing; only one freeze-thaw cycle is advised. When an unstable gel is frozen and later thawed, its texture and structural may be compromised by the physical changes. To offset this effect and promote freeze-thaw stability, a second thickening hydrocolloid may be added to the gel system.
 * 1. Briefly explain freeze thaw stability of gel . **

From the article ‘Designing Sauces that Stand Up’ Some hydrocolloids form gels in the presence of positively charged ions, mainly calcium and potassium. In these instances, the positive ion fits into negatively charged areas in the hydrocolloid, allowing two hydrocolloid molecules to stick together in a structure similar to an egg-crate. In some cases, like alginates, these gels are not reversible; in others, like kappa carrageenan, thermo-reversible gels are formed. It is extremely important to control the amount of calcium in solution when dealing with calcium-dependent hydrocolloids. If too much calcium is present, the hydrocolloid will gel immediately, a process that is called pre-gelation. Sometimes, the hydrocolloid simply will not hydrate in a recipe. In these cases, chemicals called sequestrants are added to these solutions to prevent pre-gelation and allow proper hydration. Sequestrants have the ability to bind with ions like calcium more effectively than hydrocolloids can. In many cases, the amount of calcium in tap water alone can cause pre-gelation of a hydrocolloid if not treated with sequestrants. Acidic solutions (low pH) also need more sequestrants than neutral solutions because many calcium impurities are more soluble and affect hydrocolloids more at low pH.
 * 2. How does calcium salt or potassium salt affect the gelation of certain hydrocolloids? **