Humans can taste one drop of sucrose (table sugar) diluted in 150 parts water. A honey bee outranks our sugar sensitivity six-times over: about one part in a thousand and the bee is on it. What about Puff, the cat?
Puff doesn’t jump on command nor does she care much for honey. Why do cats lack the fundamental sweetbuds that seem to line almost every bit of real estate on our human tongues? I, an ordinary sample human, have a sugar addiction. Cats don’t. Lucky them – they can’t taste sweetness. Rotten carcasses, however, seem to attract their licky tongues.
The science of sweetness taste-testing goes back about a hundred years. A group of three scientists – Beister, Wood, and Wahlin – working at the University of Minnesota led the way. They ‘invited’ undergrad students to lend them their tongues. Droplets of pure water (Yummy!) were placed on student sugar buds. As the experiments progressed, more and more sugar was added to the water until the students reported that they could taste the sugar. This is known as a ‘threshhold taste test’ and it was repeated by the scientists with a range of sugars – sucrose, fructose, glucose, maltose. Those four are the principal sugars in honey.
The scientists carefully tested and documented the relative sweetnesses. In their 1925 paper, Carbohydrate Studies, they wrote, “”Although the consumption of sucrose has increased rapidly…accurate information as to the relative sweetness of pure sugars is lacking.” Their research confirmed that fructose is more than twice as sweet as glucose. Food packers love information like this – they can buy half the amount of fructose and give consumers the same sweetness with fewer calories. (In a later blog post I will discuss how fructose has become a ‘bad’ sugar in recent years.)
The three scientists assigned a value of ‘100’ to sucrose. Then, comparing sucrose to the other sugars’ sweetness as judged by the college students, they derived the scale below. By the way, the researchers did their science at the University of Minnesota where they taught, marked tests, wrote papers, and advised students. But they were never paid properly nor given the title ‘professor’ because it was 1925 and they were. . . well, you know, girls, not boys.
None of this means much to a cat. Cats don’t enjoy ice cream or rocky mountain fudge. Or honey. (Good thing, house cats get plenty fat without having a sweet tooth.) So, why do some cat food makers add sugar? Well, they know that the cats’ humans will taste the stuff before passing it along to their masters.