Roselle (Hibiscus sabdariffa): Chemistry, Production, Products, and Utilization

By Abdalbasit Adam Mariod

Roselle (Hibiscus sabdariffa) Chemistry, Production, Products, and Utilization assesses the Hibiscus sabdariffa plant for food and nonfood uses, as well as for its use as fixed or essential oils.

The chapters explore Hibiscus sabdariffa breeding, production, composition, storage, and quality related to the chemistry, nutrition, antioxidant activity, and traditional uses of its bioactive components. This book also includes coverage of medicinal, pharmacological, therapeutic, and cosmetic uses of Hibiscus sabdariffa.

This book will be of interest to nutritionists, food scientists, chemists, ethnobotanists, pharmacists, academics, undergraduate and graduate students, and professionals working with medicinal plants.

• Summarizes research developments related to Hibiscus sabdariffa
• Presents the practical applications of Hibiscus sabdariffa in industries such as food, cosmetics, medicine, and flavoring
• Explains the chemistry, nutrition, and medicinal importance of Hibiscus sabdariffa and its products

• Language: English
• Publisher: Academic Press
• Release date: Jun 11, 2021
• ISBN: 9780128226933

Book preview

Chapter 1

Breeding, genetic diversity, and safe production of Hibiscus sabdariffa under climate change

Gustav Komla Mahunu,    Department of Food Science and Technology, Faculty of Agriculture, Food and Consumer Sciences, University for Development Studies, Tamale, Ghana

Abstract

Recently, the increasing consumer preference for various products of the calyces has driven production to its economic benefit. Roselle is highly perishable when fresh, and its value rises rapidly under extreme conditions of droughts or floods. In this chapter, the genetics, breeding, and safe production of Roselle amid global climatic changes are reviewed thoroughly. It was found that the conservation, cultivar improvement, and sustainable production of Roselle can be achieved when promising landraces are identified and subjected to intensive cultivation. The extensive genetic variability helps in cultivar improvement and conservation of Roselle characteristics. Other practices including intercropping, spacing, apical de-budding, seed treatment (using plant extract), soil amendment, harvesting methods, and seed storage techniques contribute to the crop growth and yield improvement. Finally, consumer safety can be achieved through appropriate use of synthetic pesticides, wastewater, and fertilizers as these are major sources of chemical and microbial contamination of Roselle products.

Keywords

Hibiscus sabdariffa; breeding; genetic diversity; production; climate change

Chapter Outline

Outline

Abbreviation 1

1.1 Introduction 1

1.2 Breeding and genetic diversity 3

1.2.1 Breeding 3

1.2.2 Genetics diversity 4

1.3 Safe production of Roselle in climate change 5

1.4 Potential sources of heavy metals and microbial contamination of Roselle 8

1.5 Conclusion 9

Acknowledgment 10

Conflict of interest 10

References 10

Abbreviation

AIVs African indigenous vegetables

1.1 Introduction

African indigenous vegetables (AIVs) remain nearly important crops that support diet, health improvement, and commercial benefits to the people of Africa. These vegetables are generally considered as underutilized crop species. By description, these crops are native and adapted fruits and vegetables gathered from wild populations, relatively easy to cultivate within a short vegetation period aided with lower inputs than other exotic (temperate) vegetables. These crops are very much acclimatized to native environmental conditions and mainly provide livelihood support toward income, health, and nutrition. AIVs continue to be part of the solution to averting hunger, malnutrition, and impacts of climate change (Stöber et al., 2017). The preference for AIVs varies across countries, thus defined by the eating habits of the peoples, availability, and quantity required for consumption (Dansi et al., 2008). Notably, approximately 1000 species of natural plant species are used as vegetables, of which the majority (80%) are leafy vegetables, with the other 20% made up of vegetables from fruits, seeds, roots and tubers, stems, and flowers (Shackleton, Pasquini, & Drescher, 2009). The quest for local innovations and discoveries of new vegetable species has significantly advanced as people search for ways to manage food insecurity and enrich their awareness of indigenous species (Maundu, Achigan-Dako, & Morimoto, 2009). Much important, the search or selection of these novel categories of AIVs has been through the introduction of species and/or depending on the native African species. Among the AIVs, Roselle in recent years has found place as a very important multipurpose indigenous vegetable across Africa. In times past, Roselle was a minor vegetable crop, but it is fast gaining attention for the food and manufacturing industries, as will be discussed subsequently.

Hibiscus sabdariffa plant produces edible calyx, belonging to a large family Malvaceae (Sharma et al., 2016). It is annual but can be cultivated as a perennial plant in the tropical and subtropical areas worldwide. In addition to the bast fiber and paper pulp or calyx, it also produces leaves and seeds (Osman et al., 2011). According to Satyanarayana, Visalakshmi, Mukherjee, Priya, and Sarkar (2015), the Roselle is considered as an important crop among the bast fiber group India, holding the second position among fiber crops after jute. Generally, the fiber is mainly used for making industrial products such as sacs, twines, and carpets. Despite its quality for fiber products in Asia, Roselle is underutilized and its fiber product is less used in the Sub-Saharan Africa (SSA) (Tetteh, Ankrah, Coffie, & Niagiah, 2019). In recent times, various products from Roselle are being explored and promoted in SSA. Salt-resistant trait in Roselle fiber makes it a perfect material for cordage production (Singh, 2017), as packaging sacks, assorted paper material, upholstery, and fabric shoes and bags production (Managooli, 2009). Roselle, in recent years, has been identified as biocomposite for the manufacturing of vehicle parts and materials for construction including fiber board (Alves et al., 2010). Actually, Roselle is estimated to be 20% of bast fiber crops.

In northern Ghana, Roselle is mostly known as sobolo or suure. The plant has more than 25 names in the tribal folks, which is a proof of Roselle domestication in the northern part of Ghana (Ankrah, Tetteh, Coffie, & Niagiah, 2018). Other common names like biito in Nankana and Frafra, vio among the Grushi and Kasem, and tingyanbam in Konkomba. Common names for Roselle vary on the basis of the geographical origin; they are Roselle, razelle, sorrel, red sorrel, Guinea sorrel, Jamaican sorrel, Indian sorrel, sour-sour, Queensland jelly plant, karkadé, Pusa hemp, rohzelu, laalambaar, sabdriqa, jelly okra, lemon bush, and Florida cranberry (Kays, 2011; Mahadevan & Kamboj, 2009; Mohamed, Sulaiman, & Dahab, 2012; Small, 2006). It appears that East Indies is probably the origin of Roselle species (Duke, 1993), with tropical Africa having extreme diversity (Wilson & Menzel, 1964).

1.2 Breeding and genetic diversity

1.2.1 Breeding

Roselle is most bred for its fiber yield (Rajasekharan, 2004). According to Wilson and Menzel (1964), Roselle is a tetraploid (2n=4x=72), the chromosomes are related to the diploid (2n=2x=36) Hibiscus cannabinus. There are two types of the Roselle plant: the H. sabdariffa var. sabdariffa (HSS) cultivated mainly for the fleshy, shiny-red caly and the H. sabdariffa var. altissima (HSA) cultivated mainly for its phloem fiber (Purseglove, 1968). There is little attention on Roselle, and information on the genetics, breeding, and production related to climate change adaptation is scarce.

The world’s largest collection of Roselle accessions (628) is by the ICAR-Central Research Institute for Jute and Allied Fibres, India (Mahapatra, 2008). There are two categories of the plant according to the growth habit and usage of the end products (Sharma et al., 2016). However, HSA category consists of plants with upright growth habit with branching at the lower part supported by an extended stem that has bast fiber of commercial use. On the other hand, the HSS category is described as bushy and has hefty branches, which bear fleshy calyces (Mahadevan & Kamboj, 2009). According to the morphological structure of the calyx, the HSS has been defined in various races. These characterizations are bhagalpuriensi (the calyces produced are bears green, red-streaked but inedible), intermedius and albus (calyces produced are edible with yellow green, some form of fiber also produced), and ruber (edible calyces produced are red) (Da-Costa-Rocha, Bonnlaender, Sievers, Pischel, & Heinrich, 2014).

Before 2009, researchers in India developed eight varieties of Roselle with high fiber content based on the selection and hybridization of indigenous landraces (Kar et al., 2010). The detection of unique germplasm with extensive diversity is essential for maintaining or improving the fiber and calyx yield in the species. For that reason, sufficient characterization of available germplasm offers the most significant opportunity in crop improvement programs. Usually, morphological attribute (based on phenotypic qualities) to select germplasm is adopted across the gene bank because it has provision for easy and quick scoring (Ganopoulos, Kazantzis, Chatzicharisis, Karayiannis, & Tsaftaris, 2011).

Environmental conditions often have a significant influence on the phenotypic traits; this can lead to an overestimated mixture of assessing agronomically important variables resulting from high gene×environment interactions (Marinoni, Akkak, Bounous, Edwards, & Botta, 2003). In the Roselle, several morphological qualities are known as a germplasm descriptor (Mahajan, Sapra, Umesh, Singh, & Sharma, 2000), which are much determined by the environment with limited success for genetic characterization of the species. Therefore agromorphological behaviors determined by molecular markers is a tool for better determination and more specific description. For decades now, molecular markers especially simple sequence repeats have shown considerable success in some crop species including rice (Nachimuthu et al., 2015), wheat (Chen, Min, Yasir, & Hu, 2012), pigeon pea (Kumari, Mishra, & Srivastava, 2014), peanut (Ren et al., 2014), and jute (Banerjee et al., 2012) for germplasm characterization, range of genetic evaluation and analysis of the population structure. These markers have shown many advantages above conservative morphological indicators. The advantages describe the fact that they are abundant, reproducible, environment and crop stage independent, high polymorphism, hypervariability, and codominant in nature (Sharma et al., 2016).

1.2.2 Genetics diversity

In recent years, it has been reported that the dearth of variability in exotic Roselle germplasm hinders the contributions to improving genetic characters (Mohammed, Islam, Jahan, Yaakob, & Osman, 2014). The study of genetic diversity in Roselle makes data available in the increased cultivar improvement and their conservation amid the changing climate. Genetic diversity is an asset to germplasm collection; thus its estimation may depend on three approaches: morphological, biochemical, or molecular evaluation (Bhandari, Bhanu, Srivastava, Singh, & Shreya, 2017). Morphological evaluation will offer less cost and the easy assessment of measurements makes it attractive to breeders to use it for genetic improvement programs. But then, morphological evaluation proves to be labor-intensive, requires large size of plant population, exhibits a low rate of polymorphism, and is inhibited by its sensitivity to the environment with higher risks of biased estimates (Botha & Venter, 2000). As mentioned earlier, the morphological approach generates sufficient information on crop physiognomies and presents the origins of beneficial genotypes for improving the traits, regardless of the weaknesses (Camussi, Ottaviano, Calinski, & Kaczmarek, 1985).

Studies on genetic diversity of Roselle (var. altissima) are rather lacking and limited with few recent reports. Some of the works include 36 accessions of wild Roselle identified in Ghana by Ankrah et al. (2018), Roselle bast fiber characterization in Kenya by Mwasiagi et al. (2014), and comparison studies of variability between kenaf and Roselle by Coffie (2017). Generally, the results of these studies showed variations in fruit morphology of Roselle across the globe (Sharma et al., 2016; Tetteh et al., 2019). The results of Tetteh et al. (2019) showed genetic variability among the plant component (seed, calyx harvests, leaves, and other yield parameters) of Roselle.

Fundamentally, the special morphological features of Roselle make it able to survive under diverse growth conditions. The special morphological features include deep taproot, which enables deep soil penetration for the search of water and minerals for growth. The height can reach up to 3.5 m with smooth or nearly smooth, cylinder-shaped stem, with dark green to red color characteristics. Comparatively, the leaves are green with reddish veins as well as long or short petioles, and they alternate with length between7.5 and 12.5 cm. The leaves of young seedlings and upper leaves of older plants look simple. The lower leaves are between three and five or even seven-lobed with saw-like margins. Flowers are about 12.5 cm wide with one each in the leaf axils. The flowers are yellow or buff colored with a rose or maroon eye and turn pink at senescence. The natural red-colored calyx has five large sepals with a collar (epicalyx) of between 8 and 12 slim, pointed bracts (or bracteole) surrounding the base. The calyx can measure to the length of about 3.2–5.7 cm, and they surround the fruit. The velvet-textured fruit pod of 1.25–2 cm length is green when immature, with –three to four seeds contained in each of the representing five valves. When fruits are mature and dry, the pods turn brown in color and rupture. Seeds appear kidney-shaped, light-brown in color, 3–5 mm long, and surrounded with miniature, stout, and stellate hairs (Mahadevan & Kamboj, 2009). All these characteristics are adaptive qualities that also guide the selection of the planting materials for crop production.

Various components (calyces, leaves, and seeds) of the Roselle can be used in fresh or dry form or even can be processed into different valuable products. Generally, there are genotypic differences in these various plant parts (calyces, leaves, and stem). There is evidence that parameters such as seed weight (kg/ha), plant population (1000/ha), number of branches per plant, number of capsules per plant, hay weight (kg/ha), and plant height can contribute to the determination of the calyx yield (kg/ha). In other words, careful selection of quality seeds based on the earlier-mentioned parameters can improve plant stand, plant architecture, and eventually increase calyx yield (Atta et al., 2011). So far, the best criteria for improving Roselle plant is by selection; study outcomes prove a positive relationship between calyx yield and important parameters (including characters of seed weight, number of branches per plant, number of capsules per plant, hay weight, and plant height) (Sabiel, Ismail, Osman, & Sun, 2014).

1.3 Safe production of Roselle in climate change

In most rural areas, women folks are in charge of the cultivation of minor vegetables, including Roselle. Roselle is planted mostly at the peripheries for farm demarcations or intercropped with staple crops. Harvested Roselle plants are processed into various products; the women enhance the market value to support the household income (Van Walsum, 2009). Although the Roselle crop typically grows as a perennial plant, it is mainly cultivated as an annual erect shrub and can be grown on the field for 5 months between planting and harvesting (Bailey & Bailey, 1976; Mohamed et al., 2012). The plant is susceptible to changes in day length; for that reason, it is recommended that the planting time is aligned more toward the proportion of the day than rainfall requirements (Mohamed et al., 2012). With the shorter days and decreased light intensity, flowering is induced, starting in September or later, depending on the growing area (Mohamed et al., 2012). Occasionally, growers in Sudan will allow seeds to ripe fully, and abscission of leaves will occur before harvesting the pods (Plotto, Mazaud, Röttger, & Steffel, 2004).

Even though Roselle does very well in soils with suitable organic materials and essential nutrients and performs adequately on moderately infertile soils, it can survive in moderately high temperature during the vegetative and fruit production phases. Nevertheless, the ideal rainfall of about 45–50 cm well distributed across the 90–120 days growth period is most suitable (Adanlawo & Ajibade, 2006). It takes between 3 and 4 months for the Roselle plants to reach commercial value at maturity before harvesting the flowers. The plant is well situated in the tropics with a fairly rainfall distribution between 1500 and 2000 mm annually from sea level to almost 600 m in altitude. The plant tolerates warmer and more humid climate with nighttime temperature of 21°C and more but cannot withstand frost and fog injury. Therefore premature flowering is possible when the plant is exposed to 13 hours of sunlight in the first months of growth (Ismail, Ikram, & Nazri, 2008).

The plant has a deep rooting system and requires in-depth preparation of seedbed. The seeding rate is between 6 and 8 kg/ha with about 2.5 cm planting depth. It is recommended that the seeds are sown at the start of the wet season at distances of 60–100 cm×45–60 cm. Larger calyces are produced when plant density is less. Sowing of seeds is by hand or use of modern grain drills. Seedling is then thinned by hand to a single plant stands to ensure appropriate plant density. There are more than 100 Roselle cultivars or varieties and the main marketable varieties are found in China, Thailand, Mexico, and Africa. In Africa, the major producing countries are Sudan, Senegal, and Mali (Ahmed, 1980; Plotto et al., 2004).

In SSA between 1961 and 2016, bast fiber crop acreage moved from 15,000 to 25,000 ha, which was approximately 67% growth. Subsequently, it declined from 1.15 to 0.67 t/ha, representing 42% decrease (Tetteh et al., 2019). Sudan is currently the leading producer of Roselle in the SSA, although producers still perceive it as a hunger crop. In addition, when farmers foresee drought, they will choose to cultivate Roselle instead of cereals; the crop is hardier in extreme weather conditions (Mohamad, Nazir, Rahman, & Herman, 2002). Available data showed that in the 2000/2001 season, total land area under Roselle cultivation was approximately 121,800 ha, compared with approximately 9370–32,950 ha in the earlier years (1970s) and about 20,160–25,160 ha in the 1980s. The increase in the cultivated land area produced extra yield; thus 454 tons in the 1960s to 26,000 tons in the 1999/2000 seasons (El-Awad, 2001). In western Sudan, Roselle serves as a vital cash crop providing substantial income for the small-scale farmers. It is grown mostly under traditional farming systems with low farm inputs and exclusively handled as a rainfed crop (El Naim & Ahmed, 2010). China and Thailand are involved in substantial Roselle production, making them major suppliers of the world. Higher-quality Roselle products are from Thailand; so, the country has made heavy investment in its production. Recently, Tetteh et al. (2019) also reported that India is the primary grower of Roselle in the world. Countries such as Mexico, Egypt, Senegal, Tanzania, Mali, and Jamaica are also important suppliers of Roselle products, but their production quantities can only meet the domestic market demands (Mohamad et al., 2002). Though Sudan produces the best Roselle in the world, the quality and quantities produced are limited by insufficient and poor handling and processing practices. The five major Roselle growing states in India (Andhra Pradesh, Bihar, Orissa, West Bengal, and Maharashtra) cultivated a total area of 84,000 ha between 2012 and 2013 (Sen & Karmakar, 2014). Satya, Karan, Kar, Mahapatra, and Mahapatra (2013) reported that Roselle jute production is only 0.55% of the cropped area in India but supports as much as 4 million farm folks, 0.25 million workers in the manufacturing industries, and 0.50 million direct traders. Roselle in Senegal is locally processed into drinks, and the local industries use a small percentage of calyces. Here, the red H. sabdariffa in Senegal in 2012 was 2885 tons and only 200 tons of was used by the local agroprocessors (Cisse et al., 2009).

Generally, there have been unlimited discussions on the safe production of vegetable crops regarding water management, synthetic pesticides use, and fertilization practices. Characteristically of most vegetable crops, Roselle is relatively responsive to poor production practices. In cases where the plant is grown in different agroclimatic places than the regions of natural origin or most conducive environment, it becomes more vulnerable to adverse soil conditions and climatic factors with significant potential yield losses. For that matter, the plants will need special care and resources to make up for the deficits.

Climate change factors, including fluctuating in temperatures, shortage of available water for irrigation or drought situation, the rate of regular to prolonged flooding, changes to extreme pH levels, and wind velocity increases, culminate in creating unsustainable vegetable farming conditions (Singh & Bainsla, 2014). Roselle plant will respond to severe environmental stress diversely according to its genotype and other crop factors (Singh et al., 2013). There is evidence that vegetable yields in tropical areas can persistently be low due to genotypic or environmental effects or their interactions (Singh et al., 2013). An estimate of 50% vegetable crop yield loss was found to be mostly due to environmental stresses (Bray, 2002), and certainly revenue from major farming choices will also be affected (Singh & Bainsla, 2014).

Over time, more and more strategies are being pursued to adapt to the potential impact of climate change (Phophi & Mafongoya, 2017; Srang-iam, 2011; Stöber et al., 2017). It requires multifaceted techniques to attain a sustainable outcome of crop productivity. For instance, diversity in parent materials has been harnessed for crop improvement. The diversity in parent materials will each time in a hybridization program produce positive effects; this means that identification of qualities that determine the total diversity of genotypes among the populations must be done well (Mehetre, Mahajan, Patil, & Hajare, 1994). The success of improving any crop depends on the nature and scope of genetic variability available in the plant (Satyanarayana et al., 2015).

1.4 Potential sources of heavy metals and microbial contamination of Roselle

Over the years, pesticides have been used to improve crop yields, and the annual demand for chemical products in agriculture has been increasing significantly. Pesticides use has diverse detrimental effects on flora, fauna, as well as the environment. More so, consumers are exposed to high chemical risk in food.

There are various ways that heavy metals from pesticides and microorganisms can contaminate Roselle (Fig. 1.1). Soil amendments with organic and inorganic fertilizers have also proved to be potential sources of heavy metals, making them bioavailable for uptake into edible parts of the plant (Chaney, 2012). Continuous crop cultivation, especially in the tropics, causes soil depletion of productive capacity, hence the need for constant replenishment with fertilizers. The increased application of organic fertilizers such as poultry manure (Delgado, Mrialles, Peralla, & Almestre, 2014) and municipal solid waste compost (Ghaly & Alkoaik, 2010) also predispose treated plants to heavy metal contamination. Polluting the air with lead (Pb) and cadmium (Cd) by vehicles will eventually find their way into the soil through precipitation and affect plant life (Popescu, 2011). In similar studies, Abubakari, Moomin, Nyarko, and Dawuda (2017) found Pb (0.8 mg/kg) and Cd (5.0 mg/kg) concentrations in Roselle leaves treated with composts to be above the maximum residue levels (MRLs) of Cd (0.2 mg/kg) and Pb (0.3 mg/kg) established by the European Commission and Codex Alimentarius Commission. It was also reported that some leafy vegetables cultivated in urban environments were contaminated with Pb levels above the MRLs (Wamalwa et al., 2015).

Figure 1.1 Flow chart of potential sources of Roselle heavy metal and microbial contamination on human and animal health.

Other sources of Roselle contamination include the use of synthetic pesticides to control plant pests. Pimentel and Levitan (1986) indicated that less than 0.1% of these pesticides are applied to reach the target pests, which means the leftover pesticides find their way into the environment to contaminate soil, water, and plants. An estimated 200,000 acute poisoning deaths occur annually due to pesticide abuse (Svensson et al., 2013), and 99% of these occurrences have been noticed in developing countries (Goldman, 2004). In the past few decades, pesticide use has increased astronomically, with most of the weaker and less firm pragmatic environmental regulations being implemented in developing countries.

The availability of water determines the plant survivability and the existence of beneficial microorganisms. In recent years, the increasing freshwater shortage is a significant challenge in crop production, especially in urban areas but more critical in the semiarid and arid regions. Consequently, farmers resort to the use of untreated wastewater as a common practice to irrigate vegetables. However, the consumption of raw leafy vegetables without appropriate decontamination of microbial load (Total coliforms, Escherichia coli) may induce adverse human health risk (Hussain & Qureshi, 2020). A study conducted by Ataogye (2012) in the Upper East Region of Ghana found that the microbial load on Roselle leaves (both dry and fresh) were higher than that of World Health Organization and the International Commission on Microbiological Specifications for Foods standards. Here, levels of total and fecal coliforms, Enterococci and E. coli were measured on both fresh and dry leaves. The study outcome indicated that decontaminated water for irrigation would reduce microbial load and lessens human health