Onion (Allium cepa L.) Thiosulfinates Respond to Increasing Sulfur Fertility

Abstract

Background. Allium species extracts including Allium cepa L. contain sulfur compounds, known for their antiplatelet, antimicrobial, antineoplasic activities. Methodology. Antibacterial activity of a formulation based on A. cepa extracts-liquid and lyophilized samples, has been demonstrated using two classes of bacteria: Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) and three methods: discs soaked with liquid extract, the wells method in the culture medium, filled with the liquid extract and lyophilized formulation extracts transformed by the incorporation of ultrapure water. The second part of this study includes identification of thiosulfinates compounds from the studied samples by high performace liquid chromatography-mass spectrometry (HPLC-MS). Results. The most important inhibition and the highest antibacterial efficiency were observed against Gram-positive bacteria, such as Staphylococcus aureus. The HPLC-MS † These authors equally contributed to this paper.

Ammonium nitrate fertility levels influence flavour development in hydroponically grown ‘Granex 33’ onion

“…The response was linear (P ≤ 0.02). Although PCSO is a minor precursor, it can accumulate to as much as 10% of the total precursor content, 27 as was the case in this study.…”

“…Thus, altering the ratios of individual flavour precursors can influence the overall flavour attributes of the onion. 27 Total precursor concentration was significantly affected by N level (P ≤ 0.001; Fig 4(A)). Total average ACSO concentrations ranged from 1.2 mg g −1 FW at 20 mg l −1 N, to 6.3 mg g −1 FW at 116 mg l −1 N. The response was quadratic (P ≤ 0.04).…”

“…Upon decomposition, 1-PRENCSO contributes to the lachrymatory factor responsible for the burning and tearing sensations, and other onion flavours. 27 PCSO was affected by N fertility level concentrations (P ≤ 0.007) and ranged from 0.04 to 0.19 mg g −1 FW, which was a fivefold increase. The response was linear (P ≤ 0.02).…”

“…The thiosulphinates resulting from the breakdown of MCSO by alliinase lend a fresh onion a cabbagelike taste to the bulb upon eating. 27 Higher N levels, therefore, should accentuate these flavours.…”

Interactions among genotype, environment and agronomic practices on production and quality of storage onion (Allium cepa L.) - A review

“…Notably, the concentration and lachrymatory factor of thiosulfonates linearly increases as the S content in the soil increases (Randle 1992a;Randle, Bussard 1993;Randle et al 1994), but pungency is not affected by high sulphur content in the soil (Hamilton et al 1997;Lee et al 2009b) and it is not correlated with S level from 16 to 97 p.m. (Yoo et al 2006). Moreover, the transcript levels of the gene associated to ferredoxin-sulphite reductase in plant roots are enhanced under sulphur sufficiency in pungent cultivars but not in the less pungent ones; moreover, the activity of ferredoxin-sulphite reductase significantly increases in response to sulphur fertilization, in the leaves of pungent cultivars but not in less pungent cultivars (McManus et al 2012).…”