Evaluation of Nutritive and Antioxidant Properties of Blanched Leafy Vegetables Consumed in Northern Côte d’Ivoire

Abstract

The aim of this study was to evaluate the effect of steam blanching processing on the nutritive value and the antioxidant properties of fi ve leafy vegetable species (Amaranthus hybridus, Andasonia digitata, Ceiba patendra, Hibiscus sabdariffa and Vigna unguiculata) that are used for sauce preparation in Northern Côte d'Ivoire. The selected leafy vegetables were subjected to blanching in pressure cooker for 15, 25 and 45 min and the physicochemical properties were determined using AOAC methods. The result of the study revealed that longer time of blanching (higher than 15 min) caused negative impact by reducing nutritive value but positive impact by reducing anti-nutrients and increasing polyphenols. The registered losses (p<0.05) at 15 min were as follow: ash (0.08-10.01%), proteins (0.36-12.03%), vitamin C (19.56-68.67%), carotenoids (18.91-55.48%) oxalates (3.58-21.39%) and phytates (10.51-68.02%). The average increase of polyphenols contents at 15 min of blanching was 1.61 to 30.72%. In addition, a slight increase (0.35-4.16%) of fi bres content was observed in the studied blanched leafy vegetables. Furthermore, after 15 min of blanching time the residual contents (p<0.05) of minerals were: calcium (264.88-844.92 mg/100 g), magnesium (49.45-435.43 mg/100 g), potassium (675-1895.41 mg/100 g), iron (14.54-70.89 mg/100 g) and zinc (9.48-36.46 mg/100 g). All these results suggest that the recommended time of domestic blanching must be less than 15 min for the studied leafy vegetables in order to contribute effi ciently to the nutritional requirement and to the food security of Ivorian population. Unauthenticated Download Date | 5/11/18 6:45 PM

A review of the contribution of cowpea leaves to food and nutrition security in East Africa

“…Variation in the blanching temperature-time combination has an effect on the nutritional composition and microbial quality of the vegetables (Njoroge et al, 2016). Oulai et al (2015) reported β-carotene and vitamin C losses of up to 55.5% and 61.1%, respectively, for cowpea vegetables blanched in a pressure cooker (121°C) for 15 min. Increasing the blanching time resulted in more nutrient losses, however, with a positive impact of reduction in antinutritional components.…”

“…Variation in the blanching temperature-time combination has an effect on the nutritional composition and microbial quality of the vegetables(Njoroge et al, 2016) Oulai et al (2015). Variation in the blanching temperature-time combination has an effect on the nutritional composition and microbial quality of the vegetables(Njoroge et al, 2016) Oulai et al (2015).…”

Chloroplast-rich material from the physical fractionation of pea vine (Pisum sativum) postharvest field residue (Haulm)

“…Previous studies on blanched leafy vegetables have also reported comparable losses of vitamin C (Oulai et al, 2015). More dramatic results are observed after wilting or fermentation as there is no retention of ascorbic acid, at least detectable by HPLC.…”

“…Next, in decreasing order of content it is found 24% of soluble proteins, 22% of total lipids and 11.5% of ash, accounting for total minerals. The relatively high proportion of total lipids contained in the chloroplast-rich material (on a dry-weight basis) as compared to total lipids from pea plants or other vegetables, which usually is no more than 5% on a dry-weight basis (Murcia, Vera & Garcia-Carmona, 1992;Oulai, Zoue & Niamke, 2015;Santos et al, 2014), is attributed to the synthesis and concentration of thylakoid membranes, rich in galactolipids, and lipid soluble pigments and vitamins in the chloroplasts. The most remarkable observation is that after processing, there is a significant decrease (p ≤ 0.05) in all macronutrients in the CRF as compared to the macronutrient content from CRF extracted from fresh biomass (Fig.…”

“…In general, blanching decreases the nutritional content in vegetables by leaching (Reyes de Corcuera et al, 2004). This is reflected in the decrease in soluble protein content (74%), due to denaturation by heat and solubilisation when washing (Murcia et al, 1992), as well as in total minerals (64%) and carbohydrates (27%) (Oulai et al, 2015;Svanberg, Nyman, Andersson & Nilsson, 1997).…”