AGRICULTURAL NEWS - Drinking that glass of orange juice is the healthy thing to do, right? Not always.
Not all South African orange juices in the shops are equally healthy. It depends on where the oranges come from, which variety used, what was added and whether the juice was freshly squeezed or made from concentrate.
This is according to Dr Cindy Hunlun, who did the first investigative study of its kind in South Africa on the content and health value of locally produced orange juice. Dr Hunlun was awarded a doctorate in Food Science on this subject by Stellenbosch University (SU) in March.
Dr Hunlun worked in the juice industry for five years before being appointed as a lecturer at the Cape Peninsula University of Technology (CPUT) and thereafter starting work on her doctorate. Her supervisor was Dr Gunnar Sigge of the SU Department of Food Science. He was assisted by Dr Dalene de Beer and Prof Jessy van Wyk.
According to Dr Sigge, quite a lot of work has been done in the agricultural industry on the cultivation and packaging of citrus fruit, but local research into its health value has been minimal.
Dr Hunlun worked in the juice industry for five years before being appointed as a lecturer at the Cape Peninsula University of Technology (CPUT) and thereafter starting work on her doctorate. Her supervisor was Dr Gunnar Sigge of the SU Department of Food Science. He was assisted by Dr Dalene de Beer and Prof Jessy van Wyk.
According to Dr Sigge, quite a lot of work has been done in the agricultural industry on the cultivation and packaging of citrus fruit, but local research into its health value has been minimal.
As much as two million tons of oranges are harvested annually for the export market and local consumption. Some of these are also processed into value-added products, such as orange juice.
Comparing oranges
As part of her research, Dr Hunlun carefully investigated the chemical and phenolic content (which influences nutritional value) of three orange varieties that are cultivated on a large scale in South Africa. These are the varieties Mandarin, Navel, and Valencia.
Comparing oranges
As part of her research, Dr Hunlun carefully investigated the chemical and phenolic content (which influences nutritional value) of three orange varieties that are cultivated on a large scale in South Africa. These are the varieties Mandarin, Navel, and Valencia.
She also compared the content of frozen orange concentrate, the juice which is eventually made from it, and freshly squeezed juice. The antioxidant levels, which are a measure of good health value, were also ascertained for each.
She collected orange juice samples from two cultivation areas (the Western and Eastern Cape) over three seasons. It was analysed to ascertain what influence variety, seasonality and cultivation area can have on fruit content.
She collected orange juice samples from two cultivation areas (the Western and Eastern Cape) over three seasons. It was analysed to ascertain what influence variety, seasonality and cultivation area can have on fruit content.
The way in which the fruit was handled after harvesting can also have an influence. Dr Hunlun found, among other things, that the antioxidant levels of Eastern Cape oranges are higher than that of fruit produced in the Western Cape and that it, therefore, has more nutritional value. These aspects are also higher in locally produced Navel and Valencia oranges than in Mandarins.
