Stephanie McCulloch, B.S. Environmental Science, Sustainable Agriculture concentration Marissa Zuckerman, B.S. Environmental Science, Economics and Nutrition Promotion minors

Department of Environmental Science, Ithaca College, Ithaca NY

Ascorbic acid content in vegetative produce cultivated in aquaponic and conventional systems: a comparative analysis

BackgroundAquaponics systems are esteemed for low environmental impacts, including resource efficiency and the removal of fertilizers and pesticides during cultivation. Aquaponic system use is expanding across the country to increase food accessibility to low-income “food deserts.” In an effort to combat both environmental and nutritional issues, the use of aquaponics is rapidly expanding. Many aquaponic firms and laboratories claim that aquaponic produce is more nutritious compared to conventional agriculture methods. However, little research has been conducted to support these claims. Aquaponics research in general is still developing as this field continues to emerge.

MethodsThe aquaponic system used for cultivation is a hydrotin grow-bed system, located in the Center for Natural Sciences (CNS) at Ithaca College. Aquaponic fish species utilized were blue tilapia (Oreochromis aureus) and bluegills (Lepomis macrochirus). Samples were cultivated to the allotted time for species maturity. Daily water quality parameters were conducted, including temperature, pH, ammonia, nitrite, and nitrate levels. Conventional samples were purchased from an independent vendor within the same time frame as aquaponic harvesting. Edible tissue samples for each produce species were tested. Samples were analyzed via high-performance liquid chromatography (HPLC) methods by an independent third-party.

PurposeThe purpose of this study is to compare the nutritional quality of three forms of vegetative produce cultivated in aquaponic systems in comparison to conventional agriculture methods: plain-leaved kale (Brassica oleracea), bell pepper (Capsicum annuum), and romaine lettuce (Lactuca sativa L. var longifolia). Our study specifically focuses on ascorbic acid content (Vitamin C), a common vitamin in the human diet found in plant matter.

Bitler, Marianne, Haider, Steven. “An Economic View of Food Deserts in the United States.” Policy Retrospectives 30.1 (2010): 153–176. Print., Dong, Diansheng, and Biing-Hwan Lin. Fruit and Vegetable Consumption by Low Income Americans: Would a Price Reduction Make a Difference?. United States Department of Agriculture, 2009. Print. Economic Research Report., Dunn, Bruce, Shrestha, Arjina. Hydroponics. Oklahoma State University, 2010. Print., Loneragan, J.F., Smith, F.W.. Plant Analysis: An Interpretation Manual. Vol. 2. Collingwood,VIC, Australia: CSIRO Publishing, 1997. Print., Morton, Lois, and Troy Blanchard. “Starved for Access: Life in Rural America’s Food Deserts.” Rural Sociological Society 1.4 (2007): 1–10. Print., Porter, Keith, Trautmann, Nancy. “Modern Agriculture: Its Effects on the Environment.” Cornell University Natural Resources Cooperative Extension (2010): n. pag. Print. United States Food and Drug Administration. A Food Labeling Guide: Reference Values for Nutrition Labeling. (2008). Print.

DiscussionResults show that conventional kale and peppers had higher concentrations of ascorbic acid, while aquaponic lettuce had higher concentrations. While there were noticeable differences in concentrations, all samples fell below average concentrations published by the U.S. Food and Drug Administration (FDA). Because results did not fall within the FDA’s average concentrations, the results of this study could be deemed inconclusive. Due to small sample sizes and limited controls, future research efforts should focus on ensuring proper protocol and system controls. Overall, this study can be utilized to encourage continued development in aquaponics research.

References

Table 1. Ascorbic acid content of three forms of vegetative produce cultivated under aquaponic and conventional agriculture methods.

0.4952.06

24

0.44

18.5

45.4

0

5

10

15

20

25

30

35

40

45

50

Lettuce Kale Pepper

AscorbicAcidContent(mg/100g)

Produce Type

AquaponicSample

ConventionalSample

Figure 1. Ascorbic acid content per 100g of lettuce, kale, and pepper analyzed.

Produce Type Cultivation Method Ascorbic Acid Content (mg/100g sampled)

Lettuce Aquaponic 0.495

Lettuce Conventional <0.440

Kale Aquaponic 2.06

Kale Conventional 18.5

Pepper Aquaponic 24.0

Pepper Conventional 45.4

Results

Images 1 and 2 (above respectively). Romaine lettuce (Lactuca sativa L. var longifolia) and bell pepper (Capsicum annuum) cultivated in the CNS Aquaponic system to maturity.