TY - JOUR

T1 - Nutritional composition in African nightshade (Solanum scabrum) influenced by harvesting methods, age and storage conditions

AU - Kirigia, Dinah

AU - Winkelmann, Traud

AU - Kasili, Remmy

AU - Mibus, Heiko

N1 - Funding Information: The authors acknowledge the German Federal Ministry of Education and Research (BMBF) for funding this project (HORTINLEA, grant number 031A248E ). The Hortinlea project is within the framework of GlobE-Global food security. We acknowledge collaborating institutions for the provision of resources, laboratory equipment’s, space and materials for this research: Leibniz University Hannover, Hochschule Geisenheim University, and Jomo Kenyatta University of Agriculture and Technology (JKUAT), Kenya. Finally, we thank the WorldVeg Arusha, Tanzania, for providing the African nightshade (Solanum scabrum var. Olevolosi) seeds for this research.

PY - 2019/7

Y1 - 2019/7

N2 - African indigenous vegetables have a great potential in improving livelihood, offering sustainable food security and solving the malnutrition crisis in sub-Saharan Africa (SSA). African nightshade (Solanum scabrum) is one of such indigenous vegetable, highly appreciated for its nutritive and pharmacological benefits. The vegetable is rich in antioxidative compounds, vitamins, carbohydrates, carotenoids, folic acid, minerals and amino acids. However, the optimal nutritional benefits of nightshade are influenced by pre-harvest physiological maturity, postharvest storage conditions and harvesting methods. We analyzed the dynamics of phytonutrients in nightshade grown under Kenyan field conditions, harvested using different methods and at different developmental stages, 30, 60, 90 and 120 d after planting (dap) and storing them at 5 °C and room temperature (RT). Harvesting by uprooting and cutting offered higher yields, but had the lowest nutrients retained after 4 d storage at RT, while picking single leaves (continuous method) had lower yields but higher nutrients retained. The total carbohydrates (glucose, fructose, sucrose and starch) and chlorophyll were highest in concentration at 60 dap (136.3 ± 2.9 g kg−1 and 5.8 ± 0.3 g kg-1 dry weight (DW) respectively). Gallic acid equivalent phenolics (GAE), catechin equivalent flavonoids (CAE), trolox equivalent antioxidants (TEA) and total carotenoids were highest in concentrations at 90 dap with 12.6 ± 1.0 g kg−1, 24.1 ± 1.6 g kg−1, 108.8 ± 6.0 g kg−1 and 1.01 ± 0.04 g kg−1 DW respectively. The mineral elements mainly remained stable during development apart from iron which was highest at 30 dap (1.3 ± 0.5 g kg−1), zinc was highest at 120 dap (62.1 ± 4.4 mg kg−1) and calcium was highest at 90 dap (24.3 ± 0.7 g kg−1 DW). A significant decline of phytonutrients was evidenced after 2 d storage at RT. At cold storage (5 °C), there was no significant decline on most of the phytonutrients, at least up to 4 d. Results in this study highlight the importance of maturity stages and low storage temperature for optimal nutrients and postharvest quality management of African nightshades.

AB - African indigenous vegetables have a great potential in improving livelihood, offering sustainable food security and solving the malnutrition crisis in sub-Saharan Africa (SSA). African nightshade (Solanum scabrum) is one of such indigenous vegetable, highly appreciated for its nutritive and pharmacological benefits. The vegetable is rich in antioxidative compounds, vitamins, carbohydrates, carotenoids, folic acid, minerals and amino acids. However, the optimal nutritional benefits of nightshade are influenced by pre-harvest physiological maturity, postharvest storage conditions and harvesting methods. We analyzed the dynamics of phytonutrients in nightshade grown under Kenyan field conditions, harvested using different methods and at different developmental stages, 30, 60, 90 and 120 d after planting (dap) and storing them at 5 °C and room temperature (RT). Harvesting by uprooting and cutting offered higher yields, but had the lowest nutrients retained after 4 d storage at RT, while picking single leaves (continuous method) had lower yields but higher nutrients retained. The total carbohydrates (glucose, fructose, sucrose and starch) and chlorophyll were highest in concentration at 60 dap (136.3 ± 2.9 g kg−1 and 5.8 ± 0.3 g kg-1 dry weight (DW) respectively). Gallic acid equivalent phenolics (GAE), catechin equivalent flavonoids (CAE), trolox equivalent antioxidants (TEA) and total carotenoids were highest in concentrations at 90 dap with 12.6 ± 1.0 g kg−1, 24.1 ± 1.6 g kg−1, 108.8 ± 6.0 g kg−1 and 1.01 ± 0.04 g kg−1 DW respectively. The mineral elements mainly remained stable during development apart from iron which was highest at 30 dap (1.3 ± 0.5 g kg−1), zinc was highest at 120 dap (62.1 ± 4.4 mg kg−1) and calcium was highest at 90 dap (24.3 ± 0.7 g kg−1 DW). A significant decline of phytonutrients was evidenced after 2 d storage at RT. At cold storage (5 °C), there was no significant decline on most of the phytonutrients, at least up to 4 d. Results in this study highlight the importance of maturity stages and low storage temperature for optimal nutrients and postharvest quality management of African nightshades.

KW - African nightshade

KW - Nutrients

KW - Physiological maturity

KW - Postharvest

KW - Storage

UR - http://www.scopus.com/inward/record.url?scp=85064216626&partnerID=8YFLogxK

U2 - 10.1016/j.postharvbio.2019.03.019

DO - 10.1016/j.postharvbio.2019.03.019

M3 - Article

AN - SCOPUS:85064216626

VL - 153

SP - 142

EP - 151

JO - Postharvest Biology and Technology

JF - Postharvest Biology and Technology

SN - 0925-5214

ER -