Chemical and Physical Comparison of Hydroponic and Field-Grown Tomatoes Lily Benner Advisors: Dr. Nicki Engeseth Dr. Mosbah Kushad Mentor: Jeff Kindhart Stakeholders: Dayna Conner Carl Duewer
Introduction Producing tomatoes hydroponically offers a viable way to get vine-ripened tomatoes to market early. Studies have established that vineripened tomatoes are more desirable than those ripened off the vine, but few have compared the nutrition and quality of hydroponic vine-ripened fruits to conventional field-grown ones.
Hypothesis Hydroponically produced tomatoes will be higher in bioactive compound content, have more desirable physical characteristics, and therefore be more appealing to consumers than conventional field-grown tomatoes.
Objective To determine whether hydroponically grown tomatoes provide a more nutritious, better tasting, and higher quality fruit than field production.
Specific Objectives Assess the diameter, firmness, weight, soluble solids content, ph, titratable acidity, and ascorbic acid content of ripe hydroponic tomatoes from the Rocky Top, Tribeca, Charger, Black Seaman, BHN 589, and Cabernet cultivars. Measure the above parameters for the same varieties of field tomatoes as a comparison standard. Conduct a consumer taste test to gauge acceptance of field versus hydroponic tomatoes. Perform HPLC and ORAC tests on tomato extract to compare relative levels of lycopene and antioxidants in hydroponic and conventional fruits.
Experimental Design The six tomato varieties were chosen because they were all being grown in the bags, tunnel, and field. All tomatoes are picked at pink stage (USDA stage 4) or redder. For each cultivar and method, three tomatoes are chosen at random and allowed to ripen fully. The tomatoes are coded by date and variety. Individual size and firmness tests are done on all three tomatoes. The three tomatoes are then pureed together to perform chemical tests.
Methods Size: Diameter (mm) measured using a caliper and mass (g) using a scale. Firmness: Penetrometer (kg) to determine pressure. Soluble solids content: Refractometer (degrees Brix) Acidity: ph meter and titration with NaOH Ascorbic Acid: Titration with indophenol dye Vials of tomato puree are frozen to use for ORAC and HPLC upon returning to UIUC
Reactions Total Acidity Titration with NaOH C 3 H 5 O(COOH) 3 + 3NaOH C 3 H 5 O(COO) 3 Na 3 + 3H 2 O Ascorbic Acid Titration with 2,6-Dichloroindophenol
Average Diameter (mm) Results: Physical Characteristics 80.0 Average Tomato Diameter 70.0 60.0 50.0 40.0 30.0 20.0 10.0 0.0 BH CH RT TR BS CA Cultivar
Average Tomato Mass (kg) Average Tomato Mass 200.0 180.0 160.0 140.0 120.0 100.0 80.0 60.0 40.0 20.0 0.0 BH CH RT TR BS CA Cultivar
Average Firmness (kg) 3.5 Average Tomato Firmness 3.0 2.5 2.0 1.5 1.0 0.5 0.0 BH CH RT TR BS CA Cultivar
Mass/Size (g/mm) 3.00 Average Tomato Mass to Size Ratio 2.50 2.00 1.50 1.00 0.50 0.00 BH CH RT TR BS CA Cultivar
Firmness/Size 0.0500 Average Firmness to Size Ratio 0.0450 0.0400 0.0350 0.0300 0.0250 0.0200 0.0150 0.0100 0.0050 0.0000 BH CH RT TR BS CA Cultivar
ph Results: Chemical Characteristics 4.40 4.30 4.20 4.10 4.00 3.90 3.80 Average Tomato ph 3.70 BH CH RT TR BS CA Cultivar
Titratable Acidity (g/100ml citric acid) 0.700 Average Tomato Titratable Acidity 0.600 0.500 0.400 0.300 0.200 0.100 0.000 BH CH RT TR BS CA Cultivar
Percent Brix 7.00 Average Soluble Solids 6.00 5.00 4.00 3.00 2.00 1.00 0.00 BH CH RT TR BS CA Cultivar
Ascorbic Acid (mg per ml) 0.250 Average Ascorbic Acid Content 0.200 0.150 0.100 0.050 0.000 BH CH RT TR BS CA Cultivar
Next Steps An informal sensory survey will be conducted in the near future to compare consumer preference for hydroponic and field tomatoes. Plans have been made to return to DSAC to harvest and conduct tests on field tomatoes as they become ripe. HPLC and ORAC tests will be performed on the frozen puree during the fall semester.
Outcomes The information obtained from this experiment may provide farmers with information about which method of tomato production is the best in terms of producing nutritious, large, red, sweet tomatoes, especially producing them earlier in the growing season. By collaborating with Carmen and Donny, we hope to contribute to producers ability to gain a market advantage among healthconscious consumers.