Studying different agricultural growing systems to learn the impact of various methods on the harvested food as well as the soil and other aspects of biodiversity is at best difficult. When looking at the end product (the fruit, vegetable, grain, meat, etc, intended for consumption) attributes that have been studied include nutrient content (vitamins, minerals and phytochemicals), pesticide residues, microbial pathogens and sensory properties, such as flavor, texture and appearance. Other research explores environmental impact at the farm and beyond. No wonder it's hard to sift through the news reports to make informed choices about whether or when it matters to buy organic products.
One approach consumers take is to lean toward buying organic, regardless of the debate, "just to be on the safe side." And that might be an easy decision if organic and conventional products are at price parity. That's some times the case, but more often than not, organic foods are more expensive than their conventional counterparts. Regardless of whether the rationales for purchasing organic are completely backed by science, sales of organic foods continue to climb, showing consumer preference. Top reasons for purchasing organic are health, taste and environmental impact. Because of rising popularity and the complexity of studying agricultural production systems, it's important that we continue to pay attention to new research on the impact of various production methods on nutrition, food safety and the environment. It's also key to try to consider the broader context of the research, thinking through questions like, "Is this the only study that makes this demonstration or are there several?" and "Would this study likely apply to other geographic areas?"
A review study published in 2009 that was aimed at just the nutritional profiles of organic versus conventional foods showed little difference between the two. However, critics have argued the study did not look at some nutritional attributes, such as certain antioxidants for which differences have been shown. Other published studies have looked at pesticide residues with conventional versus organic and have shown that while organic produce still does contain some pesticides, the levels are lower than found in conventional. However, the pesticide levels are usually well within the range considered safe. Some produce is more likely to contain pesticide residues than others. Earlier this year, the Environmental Working Group published the 2010 Shoppers Guide and once again conventional strawberries are near the top of the "Dirty Dozen" list, a ranking of fruits and vegetables with the highest levels and numbers of pesticide residues. A self-published analysis (that is, not subjected to more rigorous peer-review process), the ranking none the less gives consumers easy-to-use information about "cleanest" and dirtiest" produce related to pesticides.
A peer-review study was published online at PLos ONE September 1, detailing the work of University of Washington researchers who compared 15 pairs of conventional and organic strawberry growing systems in California.The scientists examined three strawberry varieties, took several samples over a two-year period and looked at mineral content, shelf life, phytochemical composition, and sensory properties of strawberries. They also analyzed solid properties. Here's what they found:
- "The organic farms had strawberries with longer shelf life, greater dry matter, and higher antioxidant activity and concentrations of ascorbic acid and phenolic compounds, but lower concentrations of phosphorus and potassium."
- One variety of organic strawberries was judged to "be sweeter and have better flavor, overall acceptance, and appearance" than its conventional counterpart, according to a sensory panel.
- The organically farmed soils had "more total carbon and nitrogen, greater microbial biomass and activity, and higher concentrations of micronutrients. Organically farmed soils also exhibited greater numbers of endemic genes and greater functional gene abundance and diversity for several biogeochemical processes, such as nitrogen fixation and pesticide degradation."
So this study shows that organic strawberry farms "produced higher quality fruit and that their higher quality soils may have greater microbial functional capability and resilience to stress."
California is the number-one state for strawberries, with farm sales "of almost $37 billion in 2007, almost double
the $19 billion (each) of number two Texas and number three Iowa." According to the California Strawberry Commission, strawberries make up over 5% of produce sales and are ranked one or two (seasonal variation) in retail fresh fruit sales in the United States. So this newly published University of Washington research is of significance.
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