Acta Hortic. 1247. ISHS 2019. DOI 10.17660/ActaHortic.2019.1247.7 Proc. IX Int. Congress on Cactus Pear and Cochineal: CAM Crops for a Hotter and Drier World Eds.: C. Sáenz et al. 47 Screening of cladodes from 42 South African spineless cactus pear cultivars for morphology, mucilage yield and mucilage viscosity M. De Wit 1,a , A. Du Toit 1 , H.J. Fouché 2 , A. Hugo 1 and S.L. Venter 2 1 University of the Free State, Nelson Mandela Drive, PO Box 339, Bloemfontein, South Africa; 2 Agricultural Research Council, 1134 Park Street, Pretoria, South Africa. Abstract In South Africa, the cactus plant is mainly used as a fodder crop, and therefore its application as a human food, especially the cladodes, should be further explored. Mucilage extracted from cladodes could be used in many different ways in food products, since it can absorb large quantities of water. It has properties similar to those of other hydrocolloids such as xanthan and guar gum. It can be used to stabilize and thicken beverages and soups, as well as being used as a foaming and suspension agent. Forty-two cultivars (Opuntia ficus-indica and Opuntia robusta) were evaluated in terms of cladode morphology (size, weight, volume, width, length, diameter and surface area), cladode moisture and solid contents, mucilage yield and mucilage viscosity. These tests were done to identify cultivars with ideal characteristics in terms of cladode dimensions and mucilage yield and viscosity. The average cladode weight was 578.53 g (ranging from 400 to 800 g), surface area 2852.96 mm 2 , volume 682,070.96 mm 3 , length 347.93 mm, width 188.95 mm and diameter 10.37 mm. The average mucilage yield was 17%, and yield ranged between 5 and 25%. The average moisture and solid contents were 87.08 and 12.92%, respectively. Cultivars were categorized into five groups in terms of mucilage viscosity, namely low, medium-low, medium, medium-high and high. Correlations between cladode size and weight, mucilage yield and viscosity as well as cladode moisture content and mucilage viscosity were determined for each cultivar. No correlation was found between size and weight of cladodes and mucilage yield (r=-0.06). Positive correlations between cladode moisture content and mucilage yield (r=0.55) and mucilage viscosity (r=0.33) were observed, while the strongest positive correlation was observed between the mucilage yield and mucilage viscosity (r=0.7). Cladode dimensions and properties were linked with mucilage yield in order to select cultivars for further analysis in food applications. Keywords: mucilage, Opuntia ficus-indica, Opuntia robusta, viscosity, yield INTRODUCTION Mucilage, a slimy liquid from cactus pear cladodes, is a complex polysaccharide carbohydrate with a highly branched structure (Trachtenberg and Mayer, 1980). Mucilage is classified as a hydrocolloid, seeing that it contains long-chain polymers that dissolve in water to give a thickening or viscosity-producing effect. Mucilage extracted from the cladodes could be used in many different ways in food products, as it has the capacity to absorb large amounts of water and is a non-Newtonian liquid (Sáenz, 2000). It could lead to the commercialization of cactus products and turn the cultivation, processing and development of new products into new business opportunities (Sumaya-Martínez et al., 2011). The aim of this research was to evaluate 42 cultivars of Opuntia spp. available at a E-mail: dewitm@ufs.ac.za