|
For many food products, salt is indispensable. Imagine the flat flavor of a dill pickle, a cured ham or a potato chip without salt. Try to effectively and economically make an emulsified meat product or a crispy cracker if salt goes missing. While excessive use and subsequent excessive intake have painted this ingredient as nutrition's foe - more about that later - most food technologists consider it a good formulating friend. Basic salt Common, or table, salt consists mainly of sodium chloride (NaCl). Food-grade salt has a fairly high purity (most commercial brands contain 99.8% to 99.95% NaCl) that varies depending on its sources and processing, but can contain other substances, especially calcium, magnesium and potassium salts. Manufacturers require a high-purity salt "in any application where the impurities will cause an adverse reaction or detract from the quality of the finished product," says Jim Barron, technical services specialist, Morton International, Inc., Chicago. "Characteristics of high-purity salt are: high sodium chloride, more than 9.93%; low calcium and magnesium, less than 60 ppm; and tight specifications for sediment, less than 1 ppm extraneous matter." Commercial salt may also contain additives, especially conditioning or free-flow agents, such as sodium hexacyanoferrate (II) decahydrate (also known as sodium ferrocyanide, yellow prussiate of soda or YPS). Although many think most salt contains iodine for fortification purposes, "very little iodized salt is used in food processing in the United States," notes Barron. "Iodized salt in this country is used in the home. In other parts of the world, iodization of salt is mandated for all salt, including salt used for food processing." Manufacturers make food-grade salt by mining underground deposits, either directly or by dissolving the salt and pumping out a saline solution, or by evaporating sea salt. They then dry the brine through solar or physical, generally vacuum-pan, methods. "Evaporated salt produced domestically is obtained by dissolving underground rock-salt deposits, or redissolving solar salt and thermally evaporating the brine," says George Lutz, quality assurance technical service manager, Cargill Salt, Minneapolis. "If brine treatment is performed, purity levels of 99.95% as sodium chloride and higher can be obtained." Today, sea salt has taken on a certain cachet. Many upscale, "gourmet" versions have been naturally evaporated by wind and sun and so contain all of the salts found in seawater, with sodium chloride at approximately 78%. "This does not meet the Food Chemicals Codex standard of 97.5% minimum for solar sodium chloride," Lutz observes. They also contain a high percentage of magnesium salts that impart a bitter taste. "In fact, they are the primary component of 'bitterns,' the salts left behind during solar-salt production of sodium chloride," he continues. "They are also highly deliquescent, drawing moisture readily from the air." However, he notes, the minimum purity of U.S. food-grade sea salt (99.8%) meets Codex criteria for both solar and evaporated sodium chloride (97.5% and 99% respectively). The shape it's in Salt crystals typically take a cubic form and are colorless. The crystal size varies when the tiny cubes bind together through ionic bonding of the sodium. And processing can provide specific sizes. These factors result in ingredients that range from a fine, pulverized salt of about 4 microns in diameter, to coarse, rock pretzel salts with a diameter of more than 1,000 microns. In addition to pulverizing or grinding salt to effect a smaller particle size, salt manufacturers can also physically compact the salt to provide a flake shape. Or, they can use the Grainer evaporation process to form pyramidal, hopper-shaped crystals, often referred to as Alberger salt, that readily break into flakes with an uneven surface that enhances cling and solubility. Food shake-out Salt is one of the four major sensory tastes and also enhances flavor, muting acidity and enhancing sweetness. In addition to this role, it also acts as a functional ingredient in many foods, contributing to their texture and structure by reacting with proteins, and controlling fermentation and lending preservation by altering aw and osmotic pressure. Among its many functions, salt strengthens the wheat gluten in dough, providing uniform grain and texture. It allows the gluten to hold more water and carbon dioxide, so the dough can easily expand without tearing. In meat, it also increases water-binding by protein, raising yield and firming the texture. Salt helps extract proteins, which promotes binding between pieces of meat in processed meats and enhances the formation of emulsion in emulsified sausages. Its many functions led to the creation of many salt forms with varying attributes: adherence, bulk density, blendability, crystal count, caking resistance, flowability, friability, liquid absorption, mean particle size, solubility and specific surface. "Most of these attributes are due to the particle size and shape of the crystal," says Lutz. "Perhaps the three most critical attributes that dictate performance are adherence, blendability and solubility. For example, does the salt adhere to the chip and provide a clean salt taste because it dissolves instantly on the tongue? Does the salt blend well due to crystal size and shape and stay blended throughout packaging, shipping, stocking and use to maintain consistent shelf appeal and flavor profile?"
|