Impact of nitrogen fertilisation on cactus pear mucilage functionality

Abstract

The spineless cactus pear (Opuntia ficus-indica) mucilage is a physically slimy, green extract that is sourced from the cladodes (modified stems) of the crop. The mucilage can be freeze-dried into a powder, and this powder has shown potential to be considered as a novel functional food biopolymer because it exhibits good functional properties, especially with regard to emulsification. The main objective of this study was to investigate whether nitrogen fertilisation had an effect on the functionality of O. ficus-indica (L.) Mill ‘Morado’ mucilage. The functionality of the mucilage was attributed to its protein content. Nitrogen is one of the main elements in soil that makes up proteins. Nitrogen fertilisers from three nitrogen sources (urea, limestone ammonium nitrate, and ammonium sulfate) were applied at four application levels (0 kg/ha, 60 kg/ha, 120 kg/ha and 240 kg/ha). The functionality of mucilage was also compared to high-protein content commercial food biopolymers known to have good functional properties. Of the parameters tested, the oil-holding and oil-absorption capacities of the mucilage were significantly affected by nitrogen fertilisation. Scanning electron microscopy revealed that all freeze-dried mucilage samples resembled broken glass or showed a flake-like structure. Different nitrogen fertilisation sources and levels appeared to have no visible morphological implications on the different freeze-dried mucilage samples evaluated.

Significance:

• The study sheds light on the functionality of freeze-dried mucilage from spineless cactus pear. It highlights the impact of nitrogen fertilisation on mucilage properties.
• The mucilage exhibits promising functional properties, particularly in emulsification. This makes it a potential novel biopolymer for food applications.
• Understanding how nitrogen affects the mucilage functionality provides insights into crop management and sustainable food production.
• The ammonium-sulfate-treated mucilage performs similarly to high-protein commercial biopolymers, suggesting its practical use in food formulations.
• These findings contribute to food science knowledge and offer sustainable alternatives for food ingredient development.