TY - JOUR

T1 - Development stage, storage temperature and storage duration influence phytonutrient content in cowpea (Vigna unguiculata L. Walp.)

AU - Kirigia, Dinah

AU - Winkelmann, Traud

AU - Kasili, Remmy

AU - Mibus, Heiko

N1 - Funding Information: This work was supported by the German federal ministry of education and research (BMBF) in collaboration with the ministry of economic cooperation and development ( HORTINLEA , grant number 031A248E ).

PY - 2018/6

Y1 - 2018/6

N2 - Cowpea (Vigna unguiculata) plays an important role in sustainable food security and livelihood improvement in Sub-Saharan Africa (SSA). The crop is rich in phytonutrients and minerals, which are key in solving malnutrition and hunger crisis, a major challenge in SSA. However, physiological status, storage temperature and duration affect phytonutrient levels and postharvest life of the leafy vegetable. Despite the significant importance of cowpeas, the maturity and postharvest storage effects on quality of the leafy vegetable remains unrevealed. The aim of this study was to analyze the dynamics of phytonutrients in cowpea leaves during development under field conditions in Kenya and in storage. The total carbohydrates (glucose, fructose, sucrose and starch) were highest at 90 d after planting (105.9 ± 2.5 g kg-1) compared to 30, 60 and 120 d. The total Phenolics (Gallic acid equivalents) increased gradually with age up to 12.0 ± 0.2 g kg-1 by 120 d. Catechin equivalent flavonoids, trolox equivalent antioxidants (TEA) and chlorophyll were highest in concentrations at 60 d after planting with 8.0 ± 0.5 g kg-1, 26.19 ± 0.5 g kg-1 and 5.7 ± 0.4 g kg-1 respectively. Quercetin equivalent flavonoids and total carotenoids did not show significant changes with age, while mineral concentration dynamics were specific for each element. Storage of cowpea leaves at room temperature (50–55 % relative humidity) led to a stronger decline of phytonutrients after 4 d, but mostly they remained stable at cold storage (5 °C). Results of this study highlight the importance of developmental stage at harvest, storage conditions and duration for the optimal availability of phytonutrients in freshly consumed leaves and for postharvest management strategies.

AB - Cowpea (Vigna unguiculata) plays an important role in sustainable food security and livelihood improvement in Sub-Saharan Africa (SSA). The crop is rich in phytonutrients and minerals, which are key in solving malnutrition and hunger crisis, a major challenge in SSA. However, physiological status, storage temperature and duration affect phytonutrient levels and postharvest life of the leafy vegetable. Despite the significant importance of cowpeas, the maturity and postharvest storage effects on quality of the leafy vegetable remains unrevealed. The aim of this study was to analyze the dynamics of phytonutrients in cowpea leaves during development under field conditions in Kenya and in storage. The total carbohydrates (glucose, fructose, sucrose and starch) were highest at 90 d after planting (105.9 ± 2.5 g kg-1) compared to 30, 60 and 120 d. The total Phenolics (Gallic acid equivalents) increased gradually with age up to 12.0 ± 0.2 g kg-1 by 120 d. Catechin equivalent flavonoids, trolox equivalent antioxidants (TEA) and chlorophyll were highest in concentrations at 60 d after planting with 8.0 ± 0.5 g kg-1, 26.19 ± 0.5 g kg-1 and 5.7 ± 0.4 g kg-1 respectively. Quercetin equivalent flavonoids and total carotenoids did not show significant changes with age, while mineral concentration dynamics were specific for each element. Storage of cowpea leaves at room temperature (50–55 % relative humidity) led to a stronger decline of phytonutrients after 4 d, but mostly they remained stable at cold storage (5 °C). Results of this study highlight the importance of developmental stage at harvest, storage conditions and duration for the optimal availability of phytonutrients in freshly consumed leaves and for postharvest management strategies.

KW - Food analysis

KW - Food science

KW - Nutrition

UR - http://www.scopus.com/inward/record.url?scp=85048335086&partnerID=8YFLogxK

U2 - 10.1016/j.heliyon.2018.e00656

DO - 10.1016/j.heliyon.2018.e00656

M3 - Article

AN - SCOPUS:85048335086

VL - 4

JO - Heliyon

JF - Heliyon

SN - 2405-8440

IS - 6

M1 - e00656

ER -