DEAR DR. BLONZ: If oxidation starts when air hits the cut surfaces of foods, then shouldn’t one avoid all the produce items that come cut and ready to use? Such as pre-chopped celery, carrot sticks and sliced mushrooms? -- P.M., Pima, Arizona

DEAR P.M.: Consumers are demanding more fresh, natural and convenient foods, but it is important to consider that fresh fruits and vegetables are living tissues that continue to “breathe” and metabolize after harvest. While this does not imply a need to avoid ready-cut produce, we should have some basic understanding of the process so that we can be smart shoppers.

Plant cells contain many enzymes, some of which are tucked away in special locations in the cell, walled off from the rest of the cellular contents. They remain there “on assignment,” so to speak -- the plant relies on these enzymes to metabolize (break down) what gets brought in. The products of these enzymatic actions get released for use by the rest of the cells, and the plant in general. The housing of powerful breakdown enzymes in special sub-cellular locations keeps them from acting on the plant’s vital components.

When a plant food is sliced or peeled, or if the plant has aged and dehydrated, there can be a break in the protective subcellular membranes insulating the cellular contents from their own breakdown enzymes. The liberated enzymes can begin to act and initiate breakdown on whatever cellular contents they come in contact with. This causes an apple or banana to brown when cut or peeled.

Oxidation is another way that foods can break down, this often coming from a reaction with oxygen. Cutting or slicing does expose cut surfaces to air and oxygen, but the effects can vary according to the type of food and the way in which the food is cut, packaged and stored.

There can be slight changes in quality and nutrient losses, but these tend to be minor. Vegetables and fruits tend to contain their own antioxidants that can help stave off damage. It will be obvious if the damage is significant, as the food will be unattractive and unpalatable. Color and flavor components are vulnerable to the attacks.

Companies that make use of minimal types of processing often rely on low temperatures, special washes and oxygen-scavenging systems to slow breakdown. There is even “active packaging” and controlled atmospheres that can safely maintain product freshness.

Ready-to-eat products tend to be more expensive, but in exchange, you should get a wholesome, convenient food. Be sure to observe freshness dating, and let your eyes and nose be your guides to assure you are getting the best product.

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.

DEAR DR. BLONZ: I have questions about surimi. I’m reading that it is a white fish that’s been washed and ground until it becomes gelatin in nature. Then it gets processed with artificial colors and flavors to resemble shellfish, most commonly crabmeat. Does this mean that the surimi used in ceviche and sushi would be raw like the fish it replaces? Should I be concerned about this? -- F.F., San Jose, California

DEAR F.F.: Surimi -- the literal meaning in Japanese being “ground meat” -- is a generic name for a type of processed seafood that was first developed in Japan, but is now widely available. Surimi is made up of less-expensive varieties of fish, such as Pacific whiting, hake and pollock, that get deboned, rinsed and minced until they’re nothing more than a bland and colorless mass. The surimi is then formed, flavored, cooked and colored to resemble more expensive fish varieties, such as crab, lobster, scallops, shrimp and even lox.

Novel processing techniques are used to put the finishing touches on surimi. In one interesting method, surimi is extruded in filaments that are then woven and glued together to resemble the texture and appearance of crabmeat muscle fibers. Amidst a salad with many ingredients, a surimi-based seafood can be difficult to distinguish from the genuine article. Because of this, shoppers should always check labels, or ask the deli attendant to verify that they’re getting the expected product.

Surimi differs from fish in that it contains a number of ingredients such as sugar, carbohydrate-based binding agents, and flavorings (which may or may not include glutamate). Surimi is low in fat like standard shellfish; however, the sodium level can be higher, and because of the added carbohydrates, surimi contains about one-third less protein.

Whatever its form, surimi is already fully cooked and ready to eat, so enjoy ceviche or sushi with no concerns in that regard. Assuming the final product has been kept under proper refrigeration, any risk of food poisoning from surimi is minimal.

DEAR DR. BLONZ: I sort my dietary supplements into multicompartment containers with snapping lids, using one compartment each day, so that I don’t have to mess with all the bottles. Is there a problem keeping them together like this? What about storage in the refrigerator? -- P.T., Phoenix

DEAR P.T.: Moisture and heat can decrease the shelf life of supplements. It is best to store supplements in a cool, dry place, avoiding extreme temperatures. Most bottles contain a moisture-absorbing packet to help preserve the product; perhaps you can distribute them into the daily containers. The bottom line, though, is that if you are dealing with short-term storage in a well-sealed container, there is little to be concerned about.

Storing in the refrigerator is usually not necessary, and raises the risk of exposure to moisture through condensation. Keep in mind that there may be specific products where storage in the refrigerator (or freezer) is recommended. Be sure to read each label for specific directions.

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.

DEAR DR. BLONZ: What is your opinion on the best nutrients in diet and supplements for the eye’s vitreous humor? I have had retinal tears in both eyes -- spontaneous, both in the past year, and had immediate laser surgery upon examination. I am 62 years old, and I am told there is nothing I can do to prevent this from happening. But I am not the type of person to do nothing; I am positive and proactive by nature, not to mention hopeful, and am not living in fear of a retinal detachment. I have now included daily servings of carotenoids, especially lutein, in my diet, and am looking into hyaluronic acid. Will these help, in your opinion? -- V., via email

DEAR V.: My sympathy on your vision issues. It is difficult when we attempt to do things right, only to experience bumps in the road. I am not a physician, nor do I have training in the optical health sciences. Given this, and the fact that I don’t know your health/lifestyle history and any associated issues or medications being used, I suggest reading the following two articles on the subject: tinyurl.com/jr65mcs, and tinyurl.com/glu85lz. (I am on the editorial board of the Berkeley Wellness Letter that produces these articles.)

Suffice it to say that the same whole-food, plant-based diet that works for most general health issues, along with limited stress and an active lifestyle, will be helpful here, as well. This should be a priority before you consider adding dietary supplements. At this point, I would encourage you to keep monitoring your vision as directed by your health professional. Being told that there is nothing you can do is a bit irksome, I agree. I am not sure what is or has been going on in your life, but you should ask about various health issues such as hypertension, diabetes, trauma, prior smoking, ongoing medications, etc. that may have contributed to your risk of this happening. Your doctor should be there for you as you attempt to better understand what might be going on and what you can do to lower the risk of additional problems.

DEAR DR. BLONZ: An acupuncturist suggested I drink water early in the morning with a little Himalayan salt dissolved in it. She said that mass-market iodized salt contains small particles of plastic from the polluted ocean. But I thought we needed iodized salt to get iodine. Can you please clarify? -- S.S., via email

DEAR S.S.: Small particles of plastic from the polluted ocean in commercial salt? Total nonsense! I would check into anything else you might hear from this individual, and take her statements with a grain of you-know-what. As for iodine, most people in the U.S. have little need for the iodine in iodized salt, as we get plenty from other food sources. This being said, there is no problem using salt with iodine added. The key with any salt is to avoid excess sodium intake.

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.