A thickening agent or thickener is a substance which can increase the viscosity of a liquid without substantially changing its other properties. Edible thickeners are commonly used to thicken sauces, soups, and puddings without altering their taste; thickeners are also used in paints, inks, explosives, and cosmetics. Thickeners may also improve the suspension of other ingredients or emulsions which increases the stability of the product. Thickening agents are often regulated as food additives and as cosmetics and personal hygiene product ingredients. Some thickening agents are gelling agents (gellants), forming a gel, dissolving in the liquid phase as a colloid mixture that forms a weakly cohesive internal structure. Others act as mechanical thixotropic additives with discrete particles adhering or interlocking to resist strain. Thickening agents can also be used when a medical condition such as dysphagia causes difficulty in swallowing. Thickened liquids play a vital role in reducing risk of aspiration for dysphagia patients. Many other food ingredients are used as thickeners, usually in the final stages of preparation of specific foods. These thickeners have a flavor and are not markedly stable, thus are not suitable for general use. However, they are very convenient and effective, and hence are widely used. Different thickeners may be more or less suitable in a given application, due to differences in taste, clarity, and their responses to chemical and physical conditions. For example, for acidic foods, arrowroot is a better choice than cornstarch, which loses thickening potency in acidic mixtures. At (acidic) pH levels below 4.5, guar gum has sharply reduced aqueous solubility, thus also reducing its thickening capability. If the food is to be frozen, tapioca or arrowroot are preferable over cornstarch, which becomes spongy when frozen. Types Food thickeners frequently are based on either polysaccharides (starches, vegetable gums, and pectin), or proteins. Starches This category includes starches as arrowroot, cornstarch, katakuri starch, potato starch, sago, wheat flour, almond flour, tapioca and their starch derivatives. A flavorless powdered starch used for this purpose is a fecula (from the Latin faecula, diminutive of faex, "dregs"). Other polymers Other sugar polymers include vegetable gums such as pectin from Citrus peel, guar gum from the guar bean, and locust bean gum from the carob bean. Agar, alginin and carrageenan are polysaccharides extracted from algae. Xanthan gum is a polysaccharide secreted by the bacterium Xanthomonas campestris and carboxymethyl cellulose is a synthetic gum derived from cellulose. Proteins used