Evaluation of the Effect of Postharvest Storage and Domestic Cooking (Steaming and Boiling) on Water-Soluble Vitamins and Minerals of Sweet Potato Leaves (Ipomoea Batatas L.)

Sweet potato plants (SPP) are a resilient wild vegetable recognized as a food crop that enhances food security in Vietnam. SPP is frequently regarded as a meal featured on the menu during nutritional consultations. Empirical evidence indicates that both harvesting and thermal processing significantly influence the composition of micronutrients. The present study investigates the stability of water-soluble vitamins and mineral elements in sweet potato plants during storage under typical domestic refrigeration conditions (i.e., storage in polythene bags at 6.2 ± 2.89 °C with a moisture content of 49 ± 13.23%) and subsequent thermal processing methods, including steaming (for 15 minutes) and boiling (for 10 minutes) in hot water. High-performance liquid chromatography (HPLC) analyses demonstrated a significant reduction (P < 0.05) in nearly all water-soluble vitamins after eight days of refrigerated storage (ranged from 86.46 % to 97.89 %). Likewise, mineral profiles quantified by inductively coupled plasma mass spectrometry (ICP-MS) exhibited distinct patterns of decline following storage (ranged from 56.35 % to 97.22 %). Compared with steaming, boiling resulted in significantly greater losses of all quantified water-soluble vitamins (P < 0.05), with vitamin retention ranging from 25.74–100 % after boiling, compared with 74.50–100 % after steaming. After boiling, vitamins B5, B6, and C were completely degraded. Mineral analysis revealed that domestic cooking significantly reduced only Na and K contents (P < 0.05); nevertheless, neither cooking method had a substantial impact on levels of Fe, Cu, Zn, Ca, and Mg (P > 0.05). All analyses were conducted in triplicate (n = 3), and data are expressed as mean ± standard deviation. Statistical significance was assessed using one-way analysis of variance (ANOVA) followed by LSD post-hoc test, with significance defined at P < 0.05. Nevertheless, neither cooking method had a substantial impact on levels of Fe, Cu, Zn, Ca, or Mg.