Light-emitting diode lighting delays changes in the postharvest nitrogen metabolism of kale (<italic>Brassica oleracea</italic> var. <italic>sabellica</italic>)

Postharvest senescence of vegetables is characterized by the degradation of pigments and proteins. Protein degradation is often accompanied by the accumulation of amino acids and ammonium since the separated plant tissues cannot recycle nitrogen. Although it is known that treatments with low-intensity white- or red-light delay protein degradation during postharvest in kale, the effect of LED lighting on nitrogen metabolism is poorly studied. The objective of this work was to evaluate the effects of LED treatments on nitrogen metabolism during postharvest kale. Three treatments were performed: control, 20–25 &#181;mol m−2 s−1 of white light or red light for 1 h. Nitrogen content remained unchanged. In the control, protein content decreased and was accompanied by the accumulation of amino acids and ammonium. In contrast, in both white and red LED light-treated leaves, protein content remained higher, and the accumulation of derivatives was delayed. Glutamine synthetase activity decreased more rapidly during storage in control than in treatments, which is related to a greater accumulation of ammonium. LED light treatments maintained a higher ascorbic acid content in kale leaves than in controls. This work demonstrates that low-intensity white or red LED treatments delay changes in postharvest nitrogen metabolism and improve the nutritional quality of kale leaves. [ABSTRACT FROM AUTHOR]