What’s the difference between conventional and organic citrus? Let’s start in what we’ll call the “beauty department.” Apart from the use of agrochemicals used while the citrus is being grown, there are several standard postharvest procedures that bear some examination. Citrus is a nonclimacteric fruit, meaning that it does not go through any pronounced ripening changes once it has been picked (compare this to a pear or an avocado, both of which are climacteric fruits). This means that citrus must be picked when it is ripe. Ripeness is determined, at least within the state of Florida, by both juice content and the Brix Acid Ratio, a measure of how much sugar is in the fruit compared to the amount of acid.
Given the unpredictability of weather and various microclimates in citrus-growing regions, sometimes citrus is fully ripe before its natural “ripe” color (orange for oranges, yellow for lemons, etc.) is well-developed. In other words, there may still be green left on fruit that is fully mature. Occasionally, fully-ripe oranges will turn green, as well—and this is perfectly natural. But, consumers are comfortable using color as a test for ripeness. Because of this, many growers feel they must alter the appearance of their citrus. According to Earthbound Farms, growers in Florida can actually dye their citrus (usually oranges) to improve color, although coloring citrus in this manner is prohibited in both California and Arizona, and organic growers are not permitted to dye fruit at all. Organic Meyer lemons from Lemon Ladies Orchard: no dye, gas or wax.
Growers can also give better color to citrus through “degreening,” a process sometimes called “gassing,” in which the citrus is exposed to ethylene gas under carefully controlled conditions. Ethylene is a gas emitted by fruit as it matures, and it causes coloration changes in the fruit’s peel. Gassing is an option for both conventional and organic growers. Although no harmful effects from ethylene have been documented when it is strictly controlled, there are people who dislike the idea of their produce having been exposed to it. Some organic growers scorn the practice, including Karen Morss of Lemon Ladies Orchard and Reena Luera of Sembra Citrus.
Waxing is another component of citrus processing. Veritable Vegetable, the country’s oldest distributor of certified organic produce, notes that a coat of wax is often applied to both conventional and organic lemons, limes, grapefruit, oranges and tangerines as a protective barrier against moisture loss and dehydration. It also gives the citrus a little more of a shine or attractive finish. Citrus actually produces a wax coating naturally, but, once it’s picked, citrus also undergoes a thorough cleaning, which can damage or destroy the wax covering. If citrus is to be shipped long distance, an insufficient wax coating might mean that the fruit reaches its destination in less than optimal condition, so additional wax is often applied.
Still, there are differences in the waxes applied to conventional and organic produce. Wax for conventional produce contains petroleum-derived ingredients, and it often has preservatives or fungicides in it. Wax is not digested by the human system, but it’s possible that chemicals in the wax may be absorbed by the body. Wax for organic produce, on the other hand, may not contain preservatives or fungicides, and it may not have petroleum-based ingredients. Beeswax, wood rosin and carnauba (extracted from palm leaves) are allowed, and they can be combined with vegetable oil, vegetable-based fatty acids, ethyl alcohol and water.
I had read online that conventional citrus fruit found in a supermarket is often several weeks away from the tree. Matt McLean, of Uncle Matt’s Organic, says that isn’t necessarily so. Like most citrus purveyors (organic or conventional), Uncle Matt’s picks to order. That is, a retailer will order a certain quantity of citrus, and only then is the fruit harvested, processed and shipped. The length of time it takes any piece of fruit to appear in a market “really depends on the retailer,” according to Mr. McLean, and how efficient it is about moving items in and out of its distribution warehouse(s). He adds that organic citrus has less of a time window than does conventional citrus. Because organic citrus is not treated preharvest or postharvest with fungicides, as is common practice for conventional citrus, the organic fruit is more subject to damage from mold exposure and temperature variations.
Once in a supermarket display, you’d think citrus would be content to behave itself and sit quietly until it’s purchased. But Mr. McLean knows that careful supervision is required, as it is for all produce. Ideally, a retailer will pick over any display of organic produce on a daily basis, to remove any items that are damaged, past their prime, or otherwise not up to par, a practice known as “turning.” While turning is done often in larger, natural food store chains, other retailers may turn less frequently. Turning is especially important for organic produce. If you’re going to pay extra for a grapefruit or potato because it’s organic, you want to walk into the organics section of your grocery store and see produce that looks perfectly fresh and vibrant.
How about nutrition content? Citrus is, of course, a great source of vitamin C, and it has some fiber and potassium, as well. Red or pink grapefruit and tangerines have a good amount of vitamin A, while fresh oranges also contain some B vitamins. But does organic citrus have more nutrition bang for your buck? Some evidence suggests that organically-grown produce may have higher levels of vitamins, minerals and/or some antioxidants.
A slightly older study (2003) claims that statistically higher levels of secondary plant metabolites (phenols, which may be important in human health) were found in both organically- and sustainably-grown marionberries, strawberries and corn than in conventionally-grown counterparts.
A more recent inquiry (2006) measured vitamin C and levels of three antioxidants in both organic- and conventionally-grown tomatoes (two separate species) and bell peppers. The results? Higher levels of vitamin C and two antioxidants were found in one variety of tomato grown organically; in a second tomatoes species, only one antioxidant had higher levels in the organically-grown specimens. Bell peppers, also examined in this study, were not statistically different in quantities of these nutrients between agricultural methods.
Organic blood oranges from Beck Grove (available
Finally, Washington State University, in research supported by The Organic Center, measured levels of two forms of three antioxidants in organic and conventional citrus, apple and tomato juices, with varying results. I liked one aspect of this study in particular, in that the researchers measured both more and less bioavailable forms of the antioxidants (bioavailability is a measure of how well substances are absorbed into the system). Unfortunately, this study was carried out with rats, not people (see this blog entry from Uncle Matt’s). Uncle Matt’s also cites the QLIF project findings, discussed in last month’s article on organic produce, the results of a four-year U.K. study on conventional versus organic produce and dairy cows. One cautionary note: While the write-up states that antioxidant levels were 20% to 40% higher in organic wheat, tomatoes, potatoes, cabbage and lettuce, levels of some nutrients were found to be higher in conventionally-grown examples of certain types of produce. Full study results will not be published until this year.
In the November 30, 2007 edition of its blog, Uncle Matt’s quotes Alyson Mitchell, an associate professor of the Department of Food, Science and Technology at University of California at Davis. Professor Mitchell declares that nutrient levels for any fruit or vegetable can vary, depending upon ripeness when picked, storage conditions, age, and especially variety (a Valencia orange may have more or less vitamin C than a Navel orange, for instance). Any processing will also affect nutritional value. To sum up, there have been a number of studies indicating higher levels of some nutrients in some organic produce. But scientific, across-the-board evidence for higher nutrition levels in organic produce in general (and organic citrus in particular) simply does not exist right now. Of course, there are a good number of other reasons to choose organic foods whenever it’s possible (pro environment, anti pesticides, supporting family farms, etc.).y seeds in their Satsumas. I found no Satsumas locally, but most supermarket tangerines were juicy, albeit a little less sweet than the organics.