DEAR DR. BLONZ: Both of the organic half-and-half products at my store are ultra-pasteurized, while the standard brands (not organic) are just pasteurized. What is the difference? -- J.J., Santa Fe, Ariz.
DEAR J.J.: Pasteurization and ultra-pasteurization are both heat treatments designed to reduce -- but not eliminate -- the presence of potentially harmful microorganisms. The two differ in the amount and duration of heat used. Pasteurization heats a dairy product to 160 degrees Fahrenheit for 15 seconds, while ultra-pasteurization heats the product up to 280 degrees Fahrenheit for up to 3 seconds. The higher heat used in ultra-pasteurization eliminates more bacteria, and results in a more shelf-stable product. Once opened, however, both types of products require refrigeration. Ultra-pasteurization is not widely used because the high heat can affect flavor. The process is usually used on products such as half-and-half or whipping cream, but ultra-pasteurized milk can be found in remote areas, or in stores that don't sell a high volume of milk.
DEAR DR. BLONZ: I have been enjoying dried apricots with breakfast, cutting them up to have with my cereal. It was pointed out that the ones I typically use are soft because they have added sulfur dioxide, and that this is something bad. Is this something I need to avoid? The ones without the sulfur dioxide are dry, leathery and difficult to cut. What is sulfur dioxide, and what purpose does it serve? What other products contain it? -- C.R. Waukesha, Wisc.
DEAR C.R.: Sulfur dioxide belongs to the group of preservatives known as the sulfites. Other sulfite preservatives include sodium sulfite, potassium sulfite, sodium metabisulfite and potassium metabisulfite. All can be used to help keep fruits and vegetables looking fresh. They can prevent discoloration as well as the growth of unwanted bacteria, molds and yeasts. Sulfur compounds are also used to help sanitize containers that are used in fermented beverages.
Sulfites are routinely used in wines and in dried fruits such as apricots, raisins, dates and figs for their antimicrobial effects, which allow for a longer shelf life. Bacteria and molds need small amounts of water to grow, so, as you noticed, apricots without sulfites (or some similar preservative) need to be dried down to that leatherlike consistency to achieve a comparable shelf life.
Sulfites are not without negatives. Some individuals experience adverse reactions to these preservatives, with symptoms ranging from headache, hives and mild shortness of breath up to a rare life-threatening breathing difficulty. The FDA estimates that about 1 percent of the general public can react in some way, and as high as 5 percent of those with asthma. The FDA has banned the use of sulfites on fresh fruits and vegetables (except potatoes) and it has to be indicated on the label whenever a sulfite preservative is present. You have been enjoying your sulfite-preserved dried apricots, so this would not appear to be an issue for you.
Send questions to: "On Nutrition," Ed Blonz, c/o Universal Uclick, 1130 Walnut St., Kansas City, MO, 64106. Send email inquiries to firstname.lastname@example.org. Due to the volume of mail, personal replies cannot be provided.