New research uses tree sap to extend shelf life of fresh fruit

University of Queensland studies have used a natural tree sap gum and light to extend the shelf life of fresh fruit and vegetables to combat food waste.

The Queensland Alliance for Agriculture and Food Innovation (QAAFI) research used edible coatings made from gum Arabic or acacia gum enriched with extracts from native Australian plants to stop the growth of spoilage causing microorganisms. The research team also used light and curcumin, a compound extracted from turmeric, to deactivate fungal spores on food.

QAAFI’s Dr Maral Seididamyeh said both methods were effective in keeping food fresh for longer. “Using our edible coating, we were able to prevent the growth of spoilage microorganisms in freshly cut capsicum for around 10 days in the fridge,” Dr Seididamyeh said. “This was mostly due to the organic acids and phenolic compounds found in the aqueous extracts of plants like Cape York lilly pilly, boonjee tamarind, and Tasmanian pepper leaves.”

The extracts showed promising antimicrobial properties and the sensory analysis also revealed the fruit looked and smelt better. The curcumin-based photosensitisation technique completely deactivated the fungal spores responsible for grey mould in fresh produce.

When applied to strawberries, it reduced decay incidence and severity by 20 per cent without compromising the fruit’s colour or firmness.”

Dr Seididamyeh said chemical-free methods for preventing food spoilage were in demand. “Bacteria, viruses, fungi and parasites are becoming resistant to synthetic chemicals used to preserve food,” Dr Seididamyeh said. “Consumers are increasingly favouring products made with natural preservatives over synthetic additives.”

Food and Agriculture Organization of the United Nations’ data showed 17 per cent of food was lost to spoilage and other issues at retail outlets and in homes.

“The research results are promising but more work is needed especially since photosensitisation is a relatively new concept in the food industry,” Dr Seididamyeh said. “Photosensitisation is already used in medicine through photodynamic therapy to destroy abnormal cells in treatment for cancer and precancerous conditions. The edible gum coating, embedded with extracts from native Australian foods and leaves, and curcumin are currently quite expensive.

To help make this a mainstream solution further funding will be needed to refine the technology for its integration into commercial packing and processing lines.

The research was funded by Hort Innovation, the Department of Primary Industries and the Australian Research Council.

The research was published in the Journal of Food Science, Food Control and Foods, and the International Journal of Biological Macromolecules.