• The effect of Pulsed Electric Field as a pre-treatment step in Ultrasound Assisted Extraction of phenolic compounds from fresh rosemary and thyme by-products, Innovative Food Science and Emerging Technologies

      Tzima, Katerina; Brunton, Nigel P.; Lyng, James G.; Frontuto, Daniele; Rai, Dilip K.; Teagasc Walsh Fellowship Programme; 2016038 (Elsevier, 2021-02-22)
      Emerging extraction techniques, including pulsed electric field (PEF) and ultrasound (US), are attracting considerable interest in the recovery of bioactives. Though, limited work has focused on PEF application as pre-treatment for US assisted extraction to enhance the release of phenolics from herbs. Hence, the present study investigated the use of an optimized PEF pre-treatment to enhance the recovery of phenolics from fresh rosemary and thyme by-products in a subsequent US assisted extraction step. Total phenolic content (TPC), 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and ferric reducing antioxidant power (FRAP) were assessed as an index of extraction efficacy. Qualitative and quantitative analyses were performed through liquid chromatography-mass spectrometry analyses to evaluate the influence of the methods on individual phenolic compounds and the formation of potential derivatives. The results indicated that in a number of cases PEF pre-treatment enhanced (p < 0.05) the recovery of phenolic compounds and antioxidant capacity compared to US individually.
    • Potential of cultivar and crop management to affect phytochemical content in winter-grown sprouting broccoli (Brassica oleracea L. var. italica)

      Reilly, Kim; Valverde, Juan; Finn, Leo; Rai, Dilip K.; Brunton, Nigel; Sorenson, Jens C; Sorenson, Hilmer; Gaffney, Michael; Department of Agriculture, Food and the Marine, Ireland; 06/NITAFRC6 (Wiley, 08/07/2013)
      BACKGROUND: Variety and crop management strategies affect the content of bioactive compounds (phenolics, flavonoids and glucosinolates) in green broccoli (calabrese) types, which are cultivated during summer and autumn in temperate European climates. Sprouting broccoli types are morphologically distinct and are grown over the winter season and harvested until early spring. Thus they show considerable potential for development as an import substitution crop for growers and consumers during the ‘hungry gap’ of early spring. The present study investigated the effect of variety and management practices on phytochemical content in a range of sprouting broccoli varieties. RESULTS: Yields were significantly higher in white sprouting broccoli varieties. Levels of phenolics and flavonoids were in the range 81.6-270.4 and 16.9–104.8 mg 100g -1 FW respectively depending on year and cultivar, and were highest in varieties TZ 5052, TZ 5055, Red Admiral and Improved White Sprouting. In-row spacing did not affect flavonoid content. Phenolic and flavonoid content generally increased with increasing floret maturity and levels were high in edible portions of the crop. Crop wastes (leaf and flower) contained 145.9-239.3 and 21.5–116.6 mg 100g -1 FW total phenolics and flavonoids respectively depending on cultivar, tissue and year. Climatic factors had a significant effect on phenolic and flavonoid content. Levels of total and some individual glucosinolates were higher in sprouting broccoli than in the green broccoli variety Ironman. CONCLUSION: Levels of total phenolics, flavonoids and glucosinolates are higher in sprouting than green broccoli types. Sprouting broccoli represents an excellent source of dietary bioactive compounds.