Case Study Report: Biomass from Spineless Opuntia ficus-Indica
Opuntia ficus-indica, commonly known as the prickly pear cactus, is a species native to Mexico and parts of the southwestern United States. It has been introduced to many other parts of the world, including South Africa, where it was first brought in as a food source and forage for livestock in the early 1800s. The species thrived in the hot and dry climate of South Africa and soon became a common sight throughout the country, particularly in the arid regions of the Northern and Western Cape.
Renewable energy sources are becoming increasingly important in the face of climate change and the need to reduce our dependence on fossil fuels. One promising alternative is biogas, a renewable energy source that can be produced from various organic materials. One such material is the spineless opuntia ficus-indica.
Spineless Opuntia Ficus-Indica as a non-invasive species
The spiny opuntia ficus-indica soon became recognized as an invasive species capable of outcompeting native vegetation and transforming ecosystems. By the mid-20th century, it had become a major problem in South Africa, with infestations covering hundreds of thousands of hectares and causing significant economic, ecological, and social impacts.
The spiny varietal of the Opuntia ficus-indica species is a 1b classified invasive species in the DEFF’s Government National Gazette titled “Alien and Invasive Species Lists, 2020,” published on 18 September 2020.
The spineless varietal, however, does not have the same invasive potential and can be easily managed within a designated plantation area. The spineless Opuntia ficus-indica Cactus is a cultivar of the Opuntia ficus-indica cactus that has been selectively bred to have absent spines on its pads. The spineless varietal is not classified as an invasive species due to a) the absence of spines which makes it palatable to herbivory grazing, and b) its slow germination rates and growth from seeds.
Spiny Opuntia Ficus Indica
Source: Forest & Kim Starr
Spineless Opuntia Ficus Indica
Source: Tropical Forages
There is, however, a worry about the potential of spineless opuntia ficus-indica cactus to become invasive by reverting to its original spiny form in naturalization. The naturalization risk is very low as Opuntia seeds in the wild have a low germination index. Additionally, the fruits are actively discouraged in the high-density planting planned for a biomass crop.
A rigorous monitoring and management regime can mitigate these risks, however low they may be. Harvesting crops before they can bear fruits is the primary defense mechanism of spreading seeds, without which the risk of naturalization is not present.
The controlled planting of spineless opuntia ficus-indica for biomass feedstock production and biogas generation could thus provide a renewable energy source while also helping to mitigate the impacts of the invasive spiny variety.
Alternative uses
Opuntia ficus-indica is a highly versatile plant with many different uses. Its fruits, known as tunas, are edible and used in various dishes in Mexican cuisine. The plant's leaves, cladodes or nopales, are also edible and are used in salads and other dishes.
In addition to its culinary uses, the Opuntia cactus has been used for centuries for its medicinal properties. It has been traditionally used to treat various ailments, including inflammation, burns, and wounds.
Opuntia ficus-indica also produces an oil that has gained attention for its potential health benefits. The oil is extracted from the seeds of the cactus fruit and is rich in antioxidants, vitamins, and essential fatty acids. This oil is known for its high levels of vitamin E, a potent antioxidant that helps protect the skin from damage caused by free radicals. Free radicals can cause premature aging, and vitamin E helps to neutralize their damaging effects. Prickly pear oil is also high in linoleic acid, an essential fatty acid that helps keep the skin hydrated and supple.
The oil is commonly used in skincare products due to its moisturizing and anti-aging properties. It can help to reduce the appearance of fine lines and wrinkles, and it is also known to be effective at reducing the appearance of hyperpigmentation and dark spots.
Prickly pear oil is also used in the culinary industry as a cooking oil and as an ingredient in salad dressings and marinades. The oil has a light, nutty flavor. It is rich in monounsaturated and polyunsaturated fatty acids, considered healthy fats that can help reduce cholesterol levels and improve heart health.