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Southern Africa faces numerous challenges, such as increasing biodiversity loss and environmental degradation. Additionally, poor and vulnerable communities suffer from undernourishment and are food insecure. Therefore, Southern Africa must adopt inclusive, sustainable food systems that support food security, even under harsh climatic conditions. Wild edible plants can potentially strengthen South African communities' diets, as they are nutritious, freely available and adapted to survive in marginal conditions. Portulacaria afra, colloquially known as spekboom, is an indigenous succulent to South Africa. This edible plant is resilient even when exposed to weather extremes and is exceptionally easy to grow. Spekboom can potentially contribute to food security since food-insecure communities can access the plant in a socially acceptable way. However, spekboom awaits culinary development to increase its consumption. This review presents the current knowledge of spekboom. As there is limited published research, the review aims to stimulate research in food science and nutrition on this undervalued plant and introduce it as a new food and ingredient. [ABSTRACT FROM AUTHOR]

Food security is threatened in Southern Africa, because of unpredictable droughts and higher summer temperatures brought on by climate change and global warming. Durable and hardy plants that grow easily and quickly in such conditions must be adopted to ensure sustainable and reliable food supplies. The young cladodes (nopalitos) from the cactus pear plant, which adapts to hot and dry climates, is an underutilised alternative food source that can serve as a healthy vegetable. It thrives in many environments such as deserts, below sea level, high altitude regions and tropical regions with temperatures above 50°C. Nopalitos are a traditional staple vegetable and have been consumed in Mexico for over 9000 years. However, it is underutilised and unknown as an alternative vegetable in Africa. Research on the physiochemical and nutritional content has been conducted. However, the information on harvesting nopalitos from cultivars available in South Africa for optimal edible quality is not available. Good quality nopalitos are young, thin, bright green, soft, fresh and not too sour or slimy. This paper aims to identify the effect of and the interaction between size, cultivar and harvesting season to obtain optimal eating quality. Data were obtained for two cultivars (Morado and Fusicaulis) at 9 cm, 12 cm, 15 cm, 18 cm, 21 cm and 24 cm, which were harvested in spring (October) and autumn (March) over two years. The quality characteristics were translated into the measurable attributes of morphology (weight, width, diameter, volume and surface area), texture (firmness and compressibility), colour (L*, a*, b*, C*and h°), turgidity (moisture content, mucilage yield and viscosity) and gustatory (percentage titratable acidity, pH and total soluble solids). ANOVA and Principal Component Analyses were performed to determine significant differences and interactions between the length groups, two cultivars and two seasons. The results showed that the size, cultivar and season influenced the edible characteristics. Both cultivars were most tender at 15 cm and presented the best edible qualities in spring. Morado showed better colour, turgidity and gustatory qualities. Morado was thinner, a brighter green colour, less sour and less slimy compared to Fusicaulis nopalitos. • Nopalito quality is highly influenced by harvest size, cultivar and season. • At 15 cm, nopalitos from both Morado and Fusicaulis were the most tender. • Morado nopalitos was the preferred cultivar, but Fusicaulis also performed satisfactorily. • Spring harvest was preferable, but autumn harvest nopalitos were acceptable. • Morado was thinner, a brighter green colour, less sour and less slimy. [ABSTRACT FROM AUTHOR]

Climate change, limited water resources and expected population increases would require crops which contribute toward more resilient, more productive, more sustainable and climate-smart food systems. The cactus pear is a drought-resistant and sustainable food source to humans and livestock alike. Cactus mucilage has multiple applications in the food and packaging industry. It is eco-friendly, economical, functional and has multiple health benefits. However, the researchers observed umpteen variations in extracted mucilage yield and viscosity every time the cladodes were harvested, making the standardisation of formulations troublesome. We aimed to examine the effect of weather conditions on the physicochemical characteristics of cactus pear cladodes and mucilage extracted over two seasons to understand these observed variations in mucilage characteristics. Forty cladodes, ten from each of Opuntia ficus-indica Algerian, Morado and Gymno-Carpo and Opuntia robusta Robusta were harvested every month from February to August in Bloemfontein, South Africa. Daily weather data were obtained, weight and moisture contents determined on cladodes and yield, viscosity, pH, conductivity and malic acid content determined on extracted mucilage. Pearson correlation coefficients were calculated between the weather conditions, cladode properties, and mucilage properties. Contrary to common belief, neither increasing cladode weight as they grow, nor rainfall were the leading causes of mucilage inconsistencies. However, the correlations showed a relationship between environmental temperatures, cladode pH and conductivity, and mucilage viscosity and yields. In hot summer weather, the pH was lower, which led to an abundance of positive ions in cladodes. The H+ ions neutralise the negative charges along the outstretched mucilage molecule, causing it to coil up, reducing the viscosity of the mucilage. Thus, environmental temperatures rather than rainfall or cladode maturity influenced the physicochemical characteristics of mucilage. The findings should make an essential contribution in predicting the physicochemical characteristics of mucilage for specific food-related functions by observing the weather conditions. [ABSTRACT FROM AUTHOR]

Cactus pear fruit is a valuable source of antioxidants and could be an important functional ingredient in foods. Cultivars differ in fruit colour, which may indicate the presence of specific antioxidants. There is increased interest for cactus pear-derived products due to their potential nutraceutical effects, and determining antioxidant potential in processed foods is an important measure to ascertain the quality of a processed product. The aim of the study was to determine the relationship of fruit processing method and colour with antioxidant content and activity in fresh and processed cactus pear fruit. Antioxidant components (ascorbic acid, phenolic compounds, carotenes and betalains) and antioxidant activity (radical scavenging activity towards 2,2′-diphenyl-1-picrylhydrazyl and iron chelating capacity) were determined in fresh and processed (juiced, dried, preserved and chutney) fruits from four different coloured cultivars (purple, green, orange and pink). The highest antioxidant content and potential was found in purple (O. robusta cv Robusta) fruit products, attributed to the highest levels of betalains (1140.4 mg kg−1). Orange fruit (O. ficus-indica) products had the second highest levels, attributed to ascorbic acid and phenolics. Betalains were highly retained in all processed products, while ascorbic acid was mostly retained in the processed products that involved minimal heat treatment. Carotene and phenolic compounds became more available for extraction during processing and showed higher levels after processing. Principal component analysis makes it possible to identify fruit colours of fresh and processed products, which were mostly associated with a specific antioxidant. In the PCA biplot, PC1 (47.93%) and PC2 (21.93%) explained 69.15% of the total variation: a processing method rather than colour-correlated products in terms of antioxidant content and potential. PCA indicated that fresh purple fruit was correlated with chelating activity and betalains, while orange fruit was clustered with phenolics, ascorbic acid, carotene and DPPH. For the processed fruit products, most were clustered together with chelating activity, DPPH and the antioxidants. Orange and pink dried products had high ascorbic acid, phenolics, carotene and DPPH values, while dried and fresh purple fruit had high betalain content and chelating activity. [ABSTRACT FROM AUTHOR]

Mucilage extracted from cactus pear cladodes is a hydrocolloid gum. It is a novel, natural, low-kilojoule, cost-effective texture-modifying ingredient in functional food products. Yet, the cultivar with the most optimal nutrient content and the preferred harvest times are as yet unknown. For this reason, mucilage from three Opuntia ficus-indica (Algerian, Morado and Gymno-Carpo) and one Opuntia robusta (Robusta) cultivar were investigated to determine their nutrient content over six months. Nutrients that contribute energy (10.2 kJ/g) were low. The mineral content was high (ash 17.7/100 g), particularly calcium (3.0 g/100 g) and phosphorous (109.5 mg/kg). Low insoluble acid-detergent fibre (1.4 g/kg) and neutral-detergent fibre (2.1 g/kg) values indicated that mucilage was mostly soluble fibre. Calcium oxalate crystals were not detected in dried mucilage. Opuntia robusta powders had higher protein, extractable fat and potassium content, while Opuntia ficus-indica mucilage powders had higher polyunsaturated (Linoleic and α-Linolenic acid) fat content. O. robusta Robusta mucilage, harvested after the fruit harvest (February) had the lowest energy content and the highest mineral and protein content. Mucilage powders were highly soluble, low-kilojoule and mineral-rich. This is a functional ingredient that is produced from an easily cultivated crop, as cactus pears grow in areas with poor soil, extremely high daytime temperatures and limited water supplies. [ABSTRACT FROM AUTHOR]

Wild-growing edible flora should be investigated to improve human food sustainability and security. Portulacaria afra (spekboom) is an undervalued edible succulent plant that thrives in harsh conditions in Southern Africa. This study determined whether the indigenous edible spekboom can be harnessed as a sustainable, nutritious food source and ingredient. Physicochemical and nutritional analyses were conducted on fresh and processed leaves (preserves, chutney, pickles, and spice). The physicochemical characteristics included morphology, color, texture, °Brix, pH, water activity, moisture content, titratable acidity, and ascorbic acid. Nutritional value determinants included crude protein, crude fiber, gross energy, and total fat content. The small, dark green fresh leaves had a soft texture and a very low sugar and fat content. Although the water content was high, water activity was low. The pH and titratable acidity showed high acidity. Leaves were high in ascorbic acid and low in protein, energy, insoluble fiber, and total fats. The leaves were successfully processed into preserved products providing possible applications in the food industry other than fresh leaves. The high acidity could be researched for application as a functional ingredient. This study provided basic information on an unexplored plant that may have potential in the food industry. [ABSTRACT FROM AUTHOR]

Natural food items and the additional benefits they provide have received considerable attention in recent years. Betalains are nutritious pigments which have valuable biological properties, e.g., antioxidant and free radical scavenging activity. In this study, aqueous betalain extracts were obtained from different coloured cactus pears (purple, red/pink, and orange), amaranth, and beetroot, with and without the addition of ascorbic acid, microwave-heated, and freeze-dried and subsequently analysed by thin layer chromatography (TLC). Beetroot samples without the addition of ascorbic acid (AA) had lower phenols, flavonoids, and ascorbic acid content than beetroot samples extracted with the addition of AA. Amaranth had significantly higher contents of antioxidants than all the other plants. Results for phenolic compounds showed that there were no significant differences between cactus pear cultivars, however, significant differences were seen between the two beetroot samples (microwave-heated with and without AA) as well as amaranth. For flavonoid compounds, amaranth had significantly higher values than all other samples. The lowest flavonoid content was found in beetroot without AA (0.49 mgCE/g). For ascorbic acid, significant differences were noticed between amaranth (71.71 mg/100 g) and samples from cactus pear and beetroot. TLC results showed that purple and red cactus pear samples had the most vivid colours, a reflection of the high betacyanin and betaxanthin contents in the cultivars. Moreover, extracts from cactus pear, beetroot, and amaranth were classified according to a decision tree which was designed by the Code of Federal Regulations/Food Additives Regulation of the EU. The classification of betalain pigment extracts as colouring foods was achieved through enrichment factor calculations and the colourant decision tree. The results showed that the betalain pigment extraction method used is inexpensive, time-saving, energy-saving, non-toxic, and chemical solvent free and yields high concentrations of betalains. [ABSTRACT FROM AUTHOR]