Vol.:(0123456789) 1 3 Journal of Food Measurement and Characterization https://doi.org/10.1007/s11694-019-00154-z ORIGINAL PAPER Cactus pear antioxidants: a comparison between fruit pulp, fruit peel, fruit seeds and cladodes of eight diferent cactus pear cultivars (Opuntia ficus-indica and Opuntia robusta) Maryna de Wit 1  · Alba du Toit 2  · Gernot Osthof 1  · Arno Hugo 1 Received: 26 September 2018 / Accepted: 2 May 2019 © Springer Science+Business Media, LLC, part of Springer Nature 2019 Abstract The cactus pear plant is an under-valued food source with health-promoting properties that thrives in arid and semi-arid regions due to its efcient use of water. Eight South African cultivars from two Opuntia species were investigated for their antioxidant content and potential. The fresh fruit (pulp), peel, seeds and cladodes of each cultivar were compared in the study. Analysis included betalains, ascorbic acid, phenolics and carotenoids. The activity of the antioxidants were deter- mined by using the DPPH method and by measuring the chelating activity of ferrous ions. When % DPPH was tested, peel and cladodes were consistently the highest, while in the % chelating activity tests, fruit pulp and seeds were the best tissue types. Cladodes contained more phenolics and carotenes than fruit regardless of the cultivar. For pulp and peel, the culti- var that contained the highest antioxidant content and potential was Robusta with its high content of betalains followed by Gymno-Carpo and Ofer with high ascorbic acid levels. The study proves that the fruit (pulp), peel and seeds from diferent cultivars contain specifc antioxidants relating to the colour of the fruit, but the cladodes of any cultivar contain similar and highly efective antioxidants. Keywords Ascorbic acid · Betalains · Carotenes · Chelating activity · DPPH · Phenolics Introduction Declining water sources and global desertifcation in many parts of the world caused researchers to pay special atten- tion to indigenous plants from arid countries in order to fnd efective food production systems and to explore pos- sible uses in the food, medical and cosmetic industries [1]. Research has revealed that Opuntia ficus-indica fruit con- tains high levels of constituents that give it value on a nutri- tional and functional basis, such as antioxidants [2, 3]. Natu- ral antioxidants from dietary sources include phenolic and polyphenolic compounds, chelators, antioxidative vitamins, enzymes and carotenoids [4]. Crops with health-promoting and nutritional benefts are gaining momentum for both pro- fessionals and consumers and cactus pears ft this trend [1]. Antioxidants are molecules that are able to reduce, delay or inhibit oxidation of other molecules even when present at very low levels. It therefore protects the body against dis- eases [3]. Recently there has been increased interest in the health-promoting capacity of antioxidants and cactus pears have been investigated in this regard. Results by Budinski et al. [5] showed that ingestion of prickly pear cladodes is efective in lowering oxidation injury and this suggests that the prickly pear plant possesses antioxidant components in the edible stems of the plant as well as the fruit. Teso- riere et al. [6] proved that a diet that includes cactus pear fruit may reduce the risk of age-related and degenerative diseases. The cactus pear fruit and cladodes are powerful antioxidant sources and could be an important additive in functional foods. The most important bio-active compounds detected in cactus fruits are phenolic compounds, betacya- nins (Bc) and betaxanthins (Bx), which have antioxidative properties [7]. Diferent cultivars of cactus pear fruit have diferent coloured fruit that may indicate the presence of * Maryna de Wit dewitm@ufs.ac.za 1 Department of Microbial, Biochemical and Food Biotechnology, Faculty of Natural and Agricultural Sciences, University of the Free State, PO Box 339, Bloemfontein 9300, South Africa 2 Department of Consumer Science, Faculty of Natural and Agricultural Sciences, University of the Free State, PO Box 339, Bloemfontein 9300, South Africa