|MadSci Network: Agricultural Sciences|
You can figure the percent of glucose in a food by dividing the weight of glucose by the weight of the food and multiplying by 100. For example, ˝ cup of grape juice weighs 125 grams and contains 4.3 grams of glucose. Therefore it is 3.4% glucose ((4.3/125) X 100 = 3.4). You can find the glucose content of other foods from an USDA bulletin available on the internet at http://www.nal.usda.gov/fnic/foodcomp/ Locate and click on “sugars” in the section “Food Composition Products”. In the “sugars” section there is an USDA bulletin that can be printed and gives the sugar content of approximately 250 foods. You might be interested in other ways to describe foods by their sugar content. Nutritionists often talk about the percent of Calories that come from sugar. The reason for this calculation is that many foods seem deceptively low in sugar, when in fact their only nutrient is sugar. For example, soft drinks are about 10% sugar but 100% of their calories come from sugar. To determine the percent of the calories that come from glucose you need to first determine how many calories are provided by glucose (there are 4 calories per gram). Then multiply the grams of glucose by 4 (in the case of grape juice there are 17 calories from glucose) and divide by the total number of calories in the food. Total number of calories in the ˝ cup grape juice is 64 which means over 25% of the calories come from glucose (17/64 X 100 = 26.6). This makes a very different comparison than the 3.4% glucose by weight. [Note you can find the calorie content of foods on the internet. The URL above also has a section called “Search the Nutrient Database”. This database has the calorie value of over 6000 foods.] Note I have used two terms above, glucose and sugar. There are several sugars in food, and glucose is not the most common. Table sugar is sucrose. It is good to learn the names of different sugars to help understand food labels and other nutrition messages. Phyllis Stumbo University of Iowa
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