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Sweeteners and Sweet Taste:
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Their application in companion animal foods and livestock feeds by Keith Klanderman, President and CEO for Nutriad, Inc
weetness is one of four to six basic taste perceptions when eating foods or drinking beverages high in sugars. The earliest example of human existence chronicled the eating of sweet fruits and plants, which were noted in paintings on cave walls in various parts of the world. Usually the tasting of sweet substances is associated with enjoyment and pleasure. Sweet, sour, salty, bitter, umami and spice are usually the perceptions that are clustered to span the range of taste sensations. Sweetness typically gets the most attention in human and animal application and this will be the focus and thrust of the article that follows.
A brief history
Many by-products are used in the feed industries that are produced during food processing activities. Some of these ingredients have high levels of sugars that can be effectively used in feeds for energy provision as well as improving palatability. Molasses from sugar cane or sugar beet processing was one of the first bulk applications of sweeteners for improving energy density in diets and providing enhanced palatability for livestock feeds. This was used for many years and continues today, but was briefly diverted during World War II to fuel the war effort by using it as a raw material to drive its fermentation to ethanol. Since farmers have grown accustomed to the use of molasses in their fields, they now needed a flavour and sugar replacement. It was at that time that the modern-day animal flavour and sweetener industry was established.
Comparing sweetness
Fructose is sweeter than glucose and sucrose. This has made possible the production of sugar syrups with the sweetness and certain other properties of sucrose starting from starch. In addition to sugars like sucrose, which typically serves as a benchmark, many other chemical compounds are sweet, including aldehydes, ketones and sugar alcohols. Even glycine and amino acids have sweet characteristics. Some are sweet at very low concentrations, allowing their application to be economically practical substitutions. Such non-sugar sweeteners include saccharin and NHDC, along with others. Aspartame is another such sweetener but it is not perceived as sweet by food producing animals. Even super high intensity sweeteners like thaumatin will elicit no sweet response unless it is bundled with other high intensity and bulk sweeteners, and then it is a species-specific response. Some components like miraculin may change perception of sweetness itself.
Response to sweetness
The electrophysiological measurements that are used to quantify sweetness along with the chemosensory basis for detecting sweetness, which varies between both individuals and species has only begun to be understood since the late 20th century. Most theoretical models of sweetness involve a three-dimensional multipoint attachment theory (much like an enzyme architecture), which involves multiple binding sites between a sweetness receptor and a sweet substance. Some of our experiences with taste physiology in the mid1990s will be referenced later in the article. Studies indicate that responsiveness to sugars and sweetness has very ancient beginnings, being manifested as chemotaxis even in motile bacteria such as E. coli. Newborn human infants and baby pigs demonstrate preferences for high sugar concentrations and prefer solutions that are sweeter than lactose, the sugar found in breast and sows milk. Sweetness appears to have the highest taste recognition threshold, being detectable at around one part in 200 of sucrose in solution. By comparison, bitterness appears to have the lowest detection threshold, at about one part in two million for quinine in solution. In natural settings for animals and humans, sweetness intensity should indicate energy density, while bitterness tends to indicate toxicity. The high sweetness detection threshold and low bitterness detection threshold would have predisposed animals to seek out sweettasting (and energy-dense) foods and avoid bitter-tasting foods. The “sweet tooth� thus has early animal consumption behavior characteristics and while feed manufacturing has 68 | June 2017 - Milling and Grain