Researcher shares secrets of onions
Eat your onions, because they contain many health-giving compounds, says a Massey University PhD student.
Srishti Joshi, who is studying plant molecular biology, said she found onions needed nitrogen and sulphur to make them grow well and taste good.
She was looking at to what extent onions grew and performed if deprived of nutrients.
Joshi was the people's choice winner in a Massey University three-minute thesis challenge, putting her almost four years of research into a presentation of just three minutes that anyone could understand.
Joshi said onions had many anti-fungal, anti-bacterial and anti-viral compounds and they might also have anti-diabetic compounds.
She said she didn't like onions when she began her research, but grew to love them, and now used them in her cooking.
Joshi said her research looked at the needs of brown onions.
"It's the nitrogen and sulphur compounds in onions that make you cry. It's that pungency that is valued in onions and they are nutritionally beneficial."
She designed her experiment so nitrogen was depleted, then sulphur and then both to see what effects on compounds in the onions each nutrient had.
She looked at 3000 compounds of onions, checking bulb, leaves and roots.
She found that the nitrogen was the primary driver of the accumulation of the nutritionally important sulphur-containing factors.
"But the interactions [between all compounds] were very complex."
Joshi said she grew the onions in Plant and Food's climate laboratory. She also had Massey University, where she is doing her PhD, as well as HortNZ, as sponsors.