Effect of continuous white light illumination on glucosinolate metabolism during postharvest storage of broccoli

Authors: CASAJUS, VICTORIA - Cellulaire Vegetale; CIVELLO, PEDRO - Cellulaire Vegetale; MARTINEZ, GUSTAVO - Cellulaire Vegetale; Howe, Kevin; Fish, Tara; Yang, Yong; Thannhauser, Theodore - Ted; Li, Li; LOBATO, MARIA - Cellulaire Vegetale

Submitted to: LWT - Food Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/11/2021
Publication Date: 3/13/2021
Citation: Casajus, V., Civello, P., Martinez, G., Howe, K.J., Fish, T., Yang, Y., Thannhauser, T.W., Li, L., Lobato, M.G. 2021. Effect of continuous white light illumination on glucosinolate metabolism during postharvest storage of broccoli. LWT - Food Science and Technology. 145:111302. https://doi.org/10.1016/j.lwt.2021.111302.
DOI: https://doi.org/10.1016/j.lwt.2021.111302

Interpretive Summary: Glucosinolates are secondary plant metabolites of the Barassicaceae. They are precursors of a class of compounds known as isothiocyanates which have been linked various health benefits including anti-inflammatory, anticancer, antibacterial activities. In this study illumination with visible white light during post-harvest storage of broccoli was shown to delay both senescence and degreening while preserving the glucosinolate content of the plant by altering the expression of genes involved in glucosinolate biosynthesis and degradation. Taken together, this process helps improve the shelf life by maintaining the eye appeal of the product but also improves its nutritional qualities.

Technical Abstract: Broccoli is a vegetable consumed globally due to its important nutritional properties, including high concentrations of glucosinolates. Light treatment can be an important tool to delay postharvest senescence. In this work it was evaluated the effect of postharvest continuous white light illumination on glucosinolate metabolism of broccoli heads. Five glucosinolates were identified, one aliphatic (glucoraphanin) and four indolics (glucobrassicin, neoglucobrassicin, 4-methoxyglucobrassicin and 4-hydroxyglucobrassicin). Level of total glucosinolates decreased from 10.1 µmol/g dry tissue to 1.4 µmol/g dry tissue in control samples after five days of storage, while the decrement was only until 3.0 µmol/g dry tissue in treated samples. The expression of genes associated with glucosinolate metabolism decreased during the first three days but this decrease was greater in illuminated samples. After five days, treated samples showed a higher expression (more than twice) in most of these genes with respect to the controls, coinciding with the higher glucosinolate content. Storage of broccoli heads under continuous white light allows to keep higher values of glucosinolate contents while maintaining at the same time the visual quality.