DEAR DR. BLONZ: We often use commercial fat-free salad dressings as an alternative to a simple olive oil and vinegar dressing. They taste fine, but my daughter asked about all the chemicals listed on the ingredients statement on the bottle. I was hoping you would tell me what xanthan gum and cellulose gel are and whether they are OK to consume regularly. -- F.F., Hayward, California
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DEAR F.F.: To be successful in the marketplace, a nonfat salad dressing has to be able to perform just like oil and vinegar and bottled, fat-based salad dressings; namely, it must coat the leaves of the lettuce, provide a pleasing mouthfeel and provide a vehicle for flavors.
Xanthan gum and cellulose gel are used precisely for these reasons, and both of these components appear to be quite safe for regular use at the level found in foods.
Xanthan gum was developed by the USDA during a project to find new uses for surplus corn. It is made from a corn syrup specially fermented from cornstarch. Xanthan gum helps to thicken the texture of food, and has proven to be quite versatile. Aside from salad dressings, it is found in puddings, sauces, baked goods and desserts. It is also found in toothpaste. Because it is made from corn, xanthan gum should be avoided by those who are allergic to corn. Aside from that, there do not appear to be problems generally associated with its use.
Cellulose gum is made from the fibrous cell walls of plants; it also functions as a thickener and is found in dressings, ice cream and puddings.
DEAR DR. BLONZ: This summer's heat is softening fruits quickly, but I hesitate to refrigerate fruits such as tomatoes, peaches and melons for fear of losing flavor. Is this a misconception, and should I go ahead and refrigerate them? -- F.M., Linden, New Jersey
DEAR F.M.: Refrigeration can slow the growth of many microorganisms, but it can also affect the quality of some foods. Tomatoes, for example, should be stored at room temperature, preferably away from direct sunlight in an airy location with moderate humidity; under these conditions they should last about five or six days. Storing a tomato in the refrigerator may delay it from going moldy, but some of its flavor and texture will be destroyed. This is particularly an issue with flavorful homegrown tomatoes and tomatoes purchased at a farmer's market. The effect is less clear with store-bought tomatoes, as they might not have as much flavor to begin with as homegrown. Another variable is sellers storing their tomatoes in the cooler.
Peaches and melons can be stored in the refrigerator, but you should wait until they are at the level of ripeness you like. (For more information on the best way to store fruits and vegetables, see b.link/n74hq9t.)
Send questions to: "On Nutrition," Ed Blonz, c/o Andrews McMeel Syndication, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to questions@blonz.com. Due to the volume of mail, personal replies cannot be provided.