Location: Food Quality LaboratoryTitle: Pre-harvest UV-B applications increases glucosinolate contents and enhances the postharvest quality of broccoli microgreen
|LU, YINGJIAN - UNIVERSITY OF MARYLAND|
|DONGG, WEN - UNIVERSITY OF TENNESSEE|
|Luo, Yaguang - Sunny|
Submitted to: Molecules
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/25/2021
Publication Date: 5/28/2021
Citation: Lu, Y., Dongg, W., Yang, T., Luo, Y., Chen, P., Wang, Q. 2021. Pre-harvest UV-B applications increases glucosinolate contents and enhances the postharvest quality of broccoli microgreen. Molecules. 26:3247. https://doi.org/10.3390/molecules26113247.
Interpretive Summary: Glucosinolates are compounds present in some plants that are beneficial to human health. Broccoli microgreens are the shoots of broccoli harvested just after the first leaves have developed. Ten to 14 day old broccoli microgreens contain high levels of glucosinolates. Previously, it has been shown that postharvest exposure of microgreens to UV-B radiation had limited effects on glucosinolate enrichment in broccoli microgreens. This study reveals that preharvest UV-B treatments significantly increased glucosinolate content in comparison to untreated microgreens. In addition, the nutritional qualities of UV-B treated microgreens were better maintained during 21-days of storage. Thus, preharvest UVB treatment is more effective on enriching the glucosinolate levels than postharvest UV-B treatment. This study provides an efficient method for microgreen growers to enhance the health-beneficial compounds in broccoli microgreens.
Technical Abstract: Broccoli microgreens have shown potential health benefits due to their high glucosinolate (GL) levels. Previously, we observed that postharvest UVB treatment did not have much effect on increasing GLs in broccoli microgreens. In this study, we investigated the influence of preharvest UVB irradiation on GL levels in broccoli microgreens. UHPLC-ESI/ITMS analysis showed that preharvest UVB treatments with UVB 0.09 and 0.27 Wh/m2 significantly increased the glucoraphanin (GLR), glucoerucin (GLE), and total aliphatic GL levels by 13.7 and 16.9%, respectively, in broccoli microgreens when measured on harvest day. The nutritional qualities of UVB-treated microgreens were stable during 21-day storage, with only small changes in their GL levels. Broccoli microgreens treated before harvest with UVB 0.27 Wh/m2 and 10 mM CaCl2 spray maintained their overall quality, and had the lowest tissue electrolyte leakage and off-odor values during the storage. Furthermore, preharvest UVB 0.27 Wh/m2 treatment significantly increased GL biosynthesis genes when evaluated before harvest, and reduced the expression level of myrosinase, a gene responsible for GL breakdown during postharvest storage. Overall, preharvest UVB treatment, together with calcium chloride spray, can increase and maintain health-beneficial compound levels such as GLs and prolong the postharvest quality of broccoli microgreens.