(P13-017-20) Impact of Food Processing on Concentrations of Metal-Binding Phytochelatins in Plant-Based Food

Objectives: Phytochelatins (PyCs), plant-derived metal-binding compounds, are widely found in plants and thought to impact absorption of metals. Our objective was to assess the impact of food processing on PyC concentrations in a set of commonly consumed plant foods in the U.S. population.

Methods: Plant food types were selected using USDA’s Food Consumption data, purchased from local grocery stores, and selected to ensure a variety of processing levels including canned, frozen, and fresh. Carrot, corn, potato, spinach, tomato and pea samples were ground, extracted, and analyzed using an optimized LC-MS/MS method for PyC detection. PyC concentrations were calculated using single-point calibration with authentic standards. Quantifiable PyCs were compared using Student’s t-test within each food type by processing level (e.g., canned vs. fresh). Additional comparisons of processing categories were completed when sample size allowed (minimum n=3 per processing category).

Results: PyC₂-Gly levels were lower in canned versus frozen or fresh carrots, corn, and peas but not potatoes, spinach or tomatoes (carrots: 1.92±1.39 vs. 8.26±1.43; corn: 1.01±0.73 vs. 9.39±2.88; peas: 0.46±0.09 vs. 1.46±0.19 µg/g fresh weight; mean±SEM, Student’s t-test, p< 0.05). In subanalyses of peas (canned vs. fresh; canned vs. frozen; frozen vs. fresh), PyC₂-Gly concentrations differed (canned: 0.46±0.09; frozen: 1.15±0.16; fresh: 1.89±0.20 µg/g fresh weight; p< 0.05). Of the four foods with quantifiable PyC₃-Gly (corn, potato, tomato, peas), only corn had lower PyC₃-Gly levels in flour or canned versus frozen or fresh (0.0014±0.0011 vs. 0.45±0.19 µg/g fresh weight). PyC₂-Ala was quantifiable in peas and corn but did not differ by processing level.

Conclusions: PyC levels were different by level of processing in some foods with higher PyC concentrations in less processed (i.e., fresh or frozen) foods. Evidence suggests PyCs may protect from absorption of dietary toxic metals such as cadmium. Dietary patterns emphasizing less processed plant foods may contain higher PyC concentrations and offer protection from toxic metals present in the diet.

Funding Sources: National Institute of Environmental Health Sciences