What was it all about?

Honey Gold mangoes are susceptible to two types of superficial defects that result in downgrading of produce and financial loss. These are…

• Under-skin browning, a type of lesion that shows up after harvesting
• Red lenticel spots, thought to be a wound response in the fruit, often associated with heavy rainfall prior to harvest.
• This project, which ran from 2013 to 2016, aimed to improve the consumer appeal and profitability of Honey Gold mango by…
• Reducing the occurrence of under-skin browning by exploring the influence of pre-harvest and harvest practices
• Identifying strategies to minimise red lenticels using inhibitors and promoters of red skin colour.

Researchers combined data from 40 previous studies to identify the most likely cause of under-skin browning. Experiments were then conducted to establish the factors that cause the bruising.

A literature review of red lenticel development informed another series of experiments to identify methods of preventing them.

Key findings included…

• Harvesting mangoes at night was the most effective practice for reducing the sensitivity of fruit to developing under-skin browning. Fruit harvested between 10 PM and 10 AM displayed 50-75 per cent reductions in browning compared to those picked at 2 PM.
• Pre-harvest bagging of fruit was the most reliable technique for reducing red lenticels. The bags block sunlight and, in turn, reduce red pigment production, including skin blush.
• Researchers also found that postharvest exposure of fruit to blue LED light for 3-4 weeks at 22°C enhanced skin blush, which could mask red lenticels.
• Preventing water entry into lenticels with pre-harvest applications of RainGard and carnauba wax also reduced red lenticel damage.

The project also confirmed previous findings that accumulated heat units is a reliable predictor for harvest dates.