DEAR DR. BLONZ: My question is about sour cream: How many days after it is opened can it be used safely, assuming it is kept refrigerated? -- D.G., San Diego
DEAR D.G.: Your sour cream should last about two weeks, assuming it has been continually refrigerated and opened before the "best by" freshness date stamped on the carton.
Several factors will influence how long any container of cold, perishable food lasts. The variables start at time of purchase: Since the time away from refrigeration should be kept to a minimum, the shopping trip to purchase refrigerated or frozen foods should be the last stop before returning home. Once there, food should be unloaded and stored promptly. (Truly, the variables begin even earlier, such as whether the product was continually refrigerated during production and transportation to the store. But such factors are outside our control.)
When using such foods, after a serving has been taken from the container, it should be resealed and returned to the fridge; the fewer the openings, the better. The storage life of the contents will decrease if the container is allowed to sit for any length of time at room temperature. And when serving, avoid using utensils that have already been used for other foods.
DEAR DR. BLONZ: I have lost almost 30 pounds on a low-carbohydrate diet, and now want to try some veggie pasta made with semolina flour. It is from a very small gourmet company, and its products do not have Nutrition Facts labels. What is semolina flour, and is it going to be appropriate for this diet? -- W.F., Lombard, Illinois
DEAR W.F.: Semolina is a coarse flour made by milling whole kernels of durum wheat. It is used in traditional pizza dough, as well as in commercial pastas and couscous. Semolina flour is relatively high in gluten protein and it absorbs little water, giving pasta and pizza dough their chewy, "al dente" texture.
The carbohydrate content will be in the same range as other wheat flours: around 100 grams per cup. You should check with the guidelines of your particular carb-controlled diet as to whether this can fit.
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.