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Effects of Household Cooking on Mineral Composition and Retention in Widespread Italian Vegetables

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Summary

Italian government research center study (Council for Agricultural Research and Economics) measuring the effect of three common household cooking methods (grilling, microwave, and steam) on mineral composition and true retention factors in zucchini (two varieties), eggplant, and potato. Magnesium concentration and true retention factors (accounting for weight change during cooking) were measured by ICP plasma after liquid washing. Zucchini had the highest magnesium content among the tested vegetables.

Key numbers

Selected magnesium values (dry weight basis, mg/100 g d.w.) from the results (p. 7 to 9):

  • Zucchini raw: 437 mg/100 g d.w. (highest macronutrient contributor after K and P) (p. 7)
  • Potato raw: 106 mg/100 g d.w. (reported for K = 2,232 mg/100 g d.w., P = 209 mg/100 g d.w., Mg = 106 mg/100 g d.w.) (p. 9)
  • Mineral retention showed “considerable heterogeneity” across cooking methods (p. 1 abstract)
  • Microwave cooking resulted in higher mineral retention than other methods for zucchini; grilling showed higher retention than microwave for eggplants (p. 1 abstract)
  • Potatoes showed lower true retention values than other vegetables; steaming produced higher retention than microwave for K, P, Fe, and Zn in potatoes (p. 1 abstract)
  • Some minerals (Na, Ca, Mn, Fe) showed more pronounced increases or losses during cooking than magnesium (p. 1 abstract)

Evidence Fitness

Reconstructable dataset. Single-country (Italy), four common Mediterranean vegetables, three cooking methods. True retention factor methodology accounts for cooking-induced weight change. Results are relevant to understanding how common cooking methods affect magnesium availability in everyday vegetables. Sample numbers not stated in abstract extract.

Methods (brief)

ICP plasma after liquid washing for mineral determination. Proximate composition by AOAC methods. True retention factor (TR) = [(mass of mineral per unit serving weight after cooking) / (mass of mineral per unit serving weight before cooking)] x 100. LOD/LOQ: limits of detection indicated as “tr” for values at or below 0.19 g/100 g in proximate analysis (p. 7 footnote).

Implications

  • Courses: relevant to discussions of how cooking method affects magnesium bioavailability in plant-based foods; zucchini is unusually magnesium-rich on a dry weight basis.
  • App: no contamination_profile implication; magnesium is a nutritional analyte here, not a hazard analyte.
  • Microbiome: no direct connection.

Provenance notes

Open access (PMC OA subset). Retrieved from PMC Open Access (pmc-oa-opendata S3). SHA256 verified against MANIFEST.csv.

Update history

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