Postharvest UV-C treatment improves health promoting plant compounds and prolongs shelf-life of vegetable amaranth Amaranthus cruentus L. (Elisha O. Gogo)
Consumption of African leafy vegetables (ALVs) has increased in Kenya, especially within urban and peri-urban areas. ALVs, such as vegetable amaranth (Amaranthus cruentus L.), are rich in bioactive compounds, e.g. protein, minerals, vitamins, dietary fiber, carotenoids and phenolic compounds, which play an important role in health promotion. However, ALVs are highly perishable; hence they suffer significant postharvest losses. The use of ultraviolet light C (UV-C) is gaining interest in improving postharvest quality and hygienic status of fruits and vegetables. Currently, only limited studies have been conducted on postharvest UV-C effects on leafy vegetables, especially ALVs. The objective of this study was to evaluate the effects of postharvest applied UV-C irradiation (254 nm) on dry weight, weight loss, main carotenoids (β-carotene, lycopene, and lutein), chlorophylls and protein of vegetable amaranth. Vegetable amaranth 'Madiira' was grown under greenhouse conditions (day/night temperatures ranging between 22-35°C/20-22°C). Eight weeks after sowing, leaves were harvested and immediately subjected to UV-C at 1.7 or 3.4 kJ m-2, while non-treated leaves served as the control. Thereafter, the leaves were stored at 5°C (85% RH) for 14 days or at 20°C (85% RH) for 6 days. Evaluations were done at 0, 2, 6 and 14 days from harvest, although evaluations were terminated early once leaves deteriorated sufficiently to be inedible. Results revealed that postharvest UV-C treatments on vegetable amaranth leaves significantly reduced weight loss compared with the control throughout storage, whereas dry weight was unaffected. UV-C treatments had significantly higher carotenoid, chlorophyll and protein content compared with the control, although it varied depending on storage conditions and applied dosage. The findings of the present study indicate that there is potential for use of UV-C as a postharvest treatment technology which is relatively safe (no residues), affordable and easy to apply. This technique would help in reducing postharvest losses and improving health promoting compounds in ALVs, which might be a promising step in improving living standards, and enhancing food, health and nutrition security in developing countries.
Elisha O. Gogo won an ISHS student award for the best oral presentation at the VI International Symposium on Improving the Performance of Supply Chains in the Transitional Economies in Australia in November 2016.
Elisha O. Gogo, Egerton University, Department of Crops, Horticulture and Soils, P.O. Box 536, 20115 Egerton, Kenya, and Humboldt-Universität zu Berlin, Faculty of Life Sciences, Division of Urban Plant Ecophysiology, Lentzeallee 55-57, 14195 Berlin, Germany, e-mail: email@example.com
The full article is available in Chronica Horticulturae