molecules Article The Chemical Composition of Oils and Cakes of Ochna serrulata (Ochnaceae) and Other Underutilized Traditional Oil Trees from Western Zambia Adela Frankova 1, Anna Manourova 2 , Zora Kotikova 3 , Katerina Vejvodova 4 , Ondrej Drabek 4, Bozena Riljakova 1, Oldrich Famera 1, Mbao Ngula 5, Mukelabai Ndiyoi 6, Zbynek Polesny 2 , Vladimir Verner 7 and Jan Tauchen 1,* 1 Department of Food Science, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences Prague, Kamycká 129, 16500 Praha-Suchdol, Czech Republic; [email protected] (A.F.); [email protected] (B.R.); [email protected] (O.F.) 2 Department of Crop Sciences and Agroforestry, Faculty of Tropical AgriSciences, Czech University of Life Sciences Prague, Kamýcká 129, 16500 Praha-Suchdol, Czech Republic; [email protected] (A.M.); [email protected] (Z.P.) 3 Department of Chemistry, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences Prague, Kamýcká 129, 16500 Praha-Suchdol, Czech Republic; [email protected] 4 Department of Soil Science and Soil Protection, Faculty of Agrobiology, Food and Natural Resources, Czech University of Life Sciences Prague, Kamýcká 129, 16500 Praha-Suchdol, Czech Republic; [email protected] (K.V.); [email protected] (O.D.) 5 ProjectEDUCATE, P.O. Box 910316, Mongu, Zambia; [email protected] 6 School of Natural Resources, University of Barotseland, P.O. Box 910316, Mongu, Zambia; Citation: Frankova, A.; Manourova, [email protected] A.; Kotikova, Z.; Vejvodova, K.; 7 Department of Economics and Development, Faculty of Tropical AgriSciences, Czech University of Life Drabek, O.; Riljakova, B.; Famera, O.; Sciences Prague, Kamýcká 129, 16500 Praha-Suchdol, Czech Republic; [email protected] Ngula, M.; Ndiyoi, M.; Polesny, Z.; * Correspondence: [email protected]; Tel.: +420-2-2438-2891 et al. The Chemical Composition of Oils and Cakes of Ochna serrulata Abstract: Currently, the negative effects of unified and intensive agriculture are of growing concern. (Ochnaceae) and Other Underutilized To mitigate them, the possibilities of using local but nowadays underused crop for food production Traditional Oil Trees from Western should be more thoroughly investigated and promoted. The soybean is the major crop cultivated Zambia. Molecules 2021, 26, 5210. for vegetable oil production in Zambia, while the oil production from local oil-bearing plants is https://doi.org/10.3390/ neglected. The chemical composition of oils and cakes of a three traditional oil plant used by molecules26175210 descendants of the Lozi people for cooking were investigated. Parinari curatellifolia and Schinziophyton Academic Editor: Vincenzo De Feo rautanenii oils were chiefly composed of α-eleostearic (28.58–55.96%), linoleic (9.78–40.18%), and oleic acid (15.26–24.07%), whereas Ochna serrulata contained mainly palmitic (35.62–37.31%), oleic Received: 13 July 2021 (37.31–46.80%), and linoleic acid (10.61–18.66%); the oil yield was high (39–71%). S. rautanenii and O. Accepted: 15 August 2021 serrulata oils were rich in γ-tocopherol (3236.18 µg/g, 361.11 µg/g, respectively). The O. serrulata oil Published: 27 August 2021 also had a very distinctive aroma predominantly composed of p-cymene (52.26%), m-xylene (9.63%), γ-terpinene (9.07%), o-xylene (7.97), and limonene (7.23%). The cakes remaining after oil extraction Publisher’s Note: MDPI stays neutral are a good source of essential minerals, being rich in N, P, S, K, Ca, and Mg. These plants have the with regard to jurisdictional claims in potential to be introduced for use in the food, technical, or pharmaceutical industries. published maps and institutional affil- iations. Keywords: oil-bearing plants; underused crops; Ochna serrulata; Schinziophyton rautanenii; Parinari curatellifolia; sustainability Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. 1. Introduction This article is an open access article The botanical diversity of vascular plants is estimated to be as high as 250,000– distributed under the terms and 300,000 species [1]; however, only about 200 species make a major contribution to food conditions of the Creative Commons production [2]. Currently, some 75% of the world’s food is generated from only twelve Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ plants, including rice, maize, and wheat [3]. Locally varied indigenous food production 4.0/). Molecules 2021, 26, 5210. https://doi.org/10.3390/molecules26175210 https://www.mdpi.com/journal/molecules Molecules 2021, 26, 5210 2 of 14 systems are thus at significant risk of being lost due to the expansion of intensive agricul- ture and concentration on a single crop. A similar trend can be seen in the loss of traditional knowledge, culture, and skills of indigenous peoples. With this decline, agrobiodiversity is also disappearing as well as many traditionally consumed edible species (including varieties), whose existence is considered to be threatened or that are already extinct [4]. Par- ticularly in developing countries, these consequences can ultimately lead to food insecurity and the use of unsafe food sources [5]. Zambia is one of the third-world countries where food security and safety are sig- nificantly worsened by agrobiodiversity loss. Parts of Zambia, especially the western province (formerly Barotseland), now suffer from hidden hunger and limited accessibility to good-quality food [6,7]. High-yielding crops such as maize, rice, cassava, mangos, tomatoes, cashew nuts, and groundnuts that require a lot of water and fertilizer are often substituted for traditional food plants and wild foods. Because of the semiarid climate in the western province, conditions for cultivation of high-value, resource-demanding species are challenging to achieve (personal communication, 28 November 2018). Given the proximity to the botanically rich South African floristic regions, Zambia has a diverse range of flowering plants covering more than 3500 species [8]. Despite this fact, the local people seem to overlook the nutritional and commercial potential in these traditionally used species, and the knowledge about these local fruits, vegetables, and oil crops is rapidly disappearing (Polesny, Z., unpublished data). The vast majority of these species have not been described by means of modern scientific methods [9]. Hence, the identification and documentation of traditional foods from developing countries is currently of the utmost in- terest. Undoubtedly it can lead to advantages to both developed and developing countries in terms of economic potential from their commercialization as food or food supplements. This can be demonstrated by açaí fruit (Euterpe oleracea) and camu camu (Myrciaria dubia). Those plants, traditionally used in South America, remained unknown to the western market until the 1990s, but nowadays are sold worldwide as rich sources of vitamin C and other antioxidants [10]. Nowadays the market with edible oils in Zambia is increasing; however, the local production covers only one-third of the market demand. The major cultivated oil-bearing plants are soybean, cotton seed and sunflower, accounting for 60, 19 and 15% of local production, respectively. Interestingly, due to the lack of knowledge about the cultivation of soybean, the plant is not very popular among farmers, and its potential remains under- developed [11]. Statistics about the oils from local plants are not available, but their use in rural areas is still current. Information gathered during a visit to the western Zambian province revealed that for food preparation people prefer to use oils obtained from the seeds of three local plants, namely Schinziophyton rautanenii, Parinari curatellifolia and Ochna serrulata, and thus, species usually used for other purposes. For example, the fruit of S. rautanenii, also known as manketti or mongongo, is reported to be an important food source for many communities in Namibia [12]. The most valuable is the kernel, from which oil and flour are obtained. The oil is rich in conjugated fatty acids, while the kernel flour is rich in essential amino acids [13]. The oil is not prone to oxidation; thus, the kernel can be stored for long time [14] and plays an important role in times of food shortage, when the nuts are ground and made into porridge (personal communication, 5 June 2019). Despite the oil being used locally for food preparation, commercially it is employed only in cosmetic products, especially in South Africa. P. curatellifolia, called mubula in the Lozi dialect, has a long tradition in folk medicine and is known for its medicinal properties, although it is also used as an oil plant. Moreover, its fruit is traditionally used for brewing beer and other alcoholic beverages [15]. O. serrulata, locally called munyelenyele, is known worldwide as an ornamental plant valued for its yellow/red flowers with nice scent and fruits resembling Mickey Mouse’s face [16]. In Africa the roots are used as a medicinal plant to treat various illnesses, e.g., bone diseases. The plant also contains biflavonoids with interesting biological properties [17]. However, information about the use of the oil from the seed has not been reported yet. Molecules 2021, 26, 5210 3 of 14 The aim of this study was to characterize the chemical and qualitative properties (fatty acid profile and content of tocopherols, macro- and microelements) of selected oils and oil cakes obtained from plants naturally occurring in the surroundings of Mongu City, Western Province, Zambia. These