Effect of Cooking Method on Vitamin C Loses and Antioxidant Activity of Indigenous Green Leafy Vegetables Consumed in Western Uganda

Abstract

Indigenous green leafy vegetables are known to contain high levels of antioxidants and are recommended in the management of chronic diseases. However, their consumption has received lower patronage. This is partly attributed to farmers replacing the growing of indigenous green leafy vegetables with their exotic counterparts and scarce information on their nutritional benefits. This study explored the effect of cooking methods (boiling and steaming for 10 minutes) on the antioxidant activity of Amaranthus dubius, Solanum nigrum, and Curcubita maxima. Spectrometry was used to evaluate the reducing power and antihemolytic activity. Titration via the 2,6-indophenol method was used for measuring vitamin C and replacement titration for hydrogen peroxide scavenging activity. Cooking the vegetables by steaming or boiling caused up to 99% reduction in the vitamin C concentration of the cooked vegetables. The antioxidant activity of the cooked vegetables varied across the species assessed and cooking method used. Steaming retained and in some instances promoted the antioxidant activity of the vegetables. The study concludes that cooking by either steaming or boiling alters the antioxidant activity of indigenous vegetables.

Variability of Nutritional, Antioxidant, and Textural Traits of a Collection of Snap Beans of Different Colors

“…On the contrary, the green and yellow lines registered the major decrements with SBP059 showing the highest significant loss (−73.9%) (Figure 4c). As well documented in the literature, the decrease in the antioxidant capacity in vegetables during cooking was attributable to the loss of antioxidants and, in particular, to the drastic reduction in the vitamin C and phenolic contents of the raw materials [59][60][61]. Here, considering the increase in some flavonoid-glucosides contents and the decrease in the TEAC observed after cooking, we can guess that in cooked snap beans, these metabolites do not contribute greatly to the antioxidant activity, and the higher contribution could be attributable to other compounds such as free phenols and vitamins losses by leaching or thermal degradation.…”

Exploration of the nutritional and carotenoids profiles of vegetables in Thai cuisine as potential nutritious ingredients

“…Vitamin C is heat labile and water−soluble. Thus, significant amounts are lost during food preparation and cooking [ 31 ]. Many examples of Thai cuisine sprinkle fresh mint leaves on top, such as Yam, Larb, and Phla (spicy Thai−style salad); consuming raw mint can provide maximum vitamin C.…”

Modern and traditional cooking methods affect the antioxidant activity and phenolic compounds content of Trachystemon Orientalis (L.) G. Don

“…CUPRAC and FRAP values of raw and cooked Trachystemon orientalis (L.) G. Don plants are provided in Table 1, and DPPH values are presented in Fig 2 . When the antioxidant activity of Trachystemon orientalis (L.) G. Don was evaluated, and it was observed that the CUPRAC value was 138.86±5.17 mmol trolox/g DW, the FRAP value was 44.74±0.59 μmol Fe (II)/g DW, and DPPH value was 0.43±0.33 mg/mL. When CUPRAC, FRAP and DPPH values were examined in many studies, it was found that the antioxidant activity of raw Trachystemon orientalis (L.) G. Don plant was higher than many plants in nature [32][33][34][35][36][37]. The average CUPRAC values of Hypericum montbretii, Paliurus spina-christi Mil and Hypericum bupleuroides were determined to be 1.07±0.14-0.19±0.05 mmol trolox/g DW [32].…”