Quality Evaluation of Sorghum bicolor Stem Sheath Enriched with Spondias mombin Extract

Sorghum is originally a wild plant in Africa, Sudan and central Asia which belongs to the family of Poaceae. The common names include millet, guinea corn, broom corn, sweet sorghum etc. In Nigeria languages, it is called Okababa (Yoruba), dawa/jero (Hausa) and soro (Igbo). The parts that are commonly used for herbal drugs include leaves, stem or grains. Different types of Sorghum bicolor are recognized including grain sorghums, sweet sorghums, and grass sorghums. It is known by a variety of names, including milo or milo-maize in the United State, dura in Sudan, great millet and guinea corn in West Africa, ka ir corn in South Africa, mtama in eastern Africa and jowar in India [1]. Sorghum [Sorghum bicolor (L) Moench] is valued for its grain, stalks and leaves. It is one of the World’s major cereal crops. Worldwide, there are a small number of grains that supply approximately 85% of the world’s food energy and only four other foods (rice, wheat, maize, and potatoes) are consumed more than sorghum. For 500 million people in over 30 countries of the semi-arid tropics, sorghum is a dietary staple. Sorghum stem sheath is popularly called ‘Karandasi’ or ‘poroporo baba’ within many localities in Nigeria and being claimed by a reasonable number of herb sellers to cure anaemia. The blood “tonic” is usually prepared by boiling the karandasi in water for 20–30 min and taken between 5 and 7days. The method of production is as described by Adetuyi et al., [2]. Sorghum stem sheath is soaked for 10mins at ambient temperature before boiling for 30mins. The extract is then iltered with cleaned muslin cloth to obtain clear solution. The liquid extracts were filtered through a 0.22 micron cellulose acetate filter to produce a sterile stock solution. The iltrate can be sweetened using food grade sucrose/honey according to individual’s preference.


Introduction
Sorghum is originally a wild plant in Africa, Sudan and central Asia which belongs to the family of Poaceae. The common names include millet, guinea corn, broom corn, sweet sorghum etc. In Nigeria languages, it is called Okababa (Yoruba), dawa/jero (Hausa) and soro (Igbo). The parts that are commonly used for herbal drugs include leaves, stem or grains. Different types of Sorghum bicolor are recognized including grain sorghums, sweet sorghums, and grass sorghums. It is known by a variety of names, including milo or milo-maize in the United State, dura in Sudan, great millet and guinea corn in West Africa, ka ir corn in South Africa, mtama in eastern Africa and jowar in India [1]. Sorghum (Sorghum bicolor (L) Moench) is valued for its grain, stalks and leaves. It is one of the World's major cereal crops. Worldwide, there are a small number of grains that supply approximately 85% of the world's food energy and only four other foods (rice, wheat, maize, and potatoes) are consumed more than sorghum. For 500 million people in over 30 countries of the semi-arid tropics, sorghum is a dietary staple. Sorghum stem sheath is popularly called 'Karandasi' or 'poroporo baba' within many localities in Nigeria and being claimed by a reasonable number of herb sellers to cure anaemia. The blood "tonic" is usually prepared by boiling the karandasi in water for 20-30 min and taken between 5 and 7days. The method of production is as described by Adetuyi, et al. [2]. Sorghum stem sheath is soaked for 10 mins at ambient temperature before boiling for 30mins. The extract is then iltered with cleaned muslin cloth to obtain clear solution. The liquid extracts were filtered through a 0.22 micron cellulose acetate filter to produce a sterile stock solution. The iltrate can be sweetened using food grade sucrose/honey according to individual's preference.
Spondias mombin tree is native and common in most lowland forests, and indigenous to tropical Africa [3]. The true yellow mombin, S. mombin L. (Syn. S. lutea L.) is most often called hog plum in the Carribean Islands [4,5]. In Jamaica, it is also known as Spanish plum, or gully plum. The yellow mombin is appreciated mostly by children and passers-by as means of alleviating thirst [6]. It is effective against anaemia, angina, anxiety, abortifacient, analgesic, anthelmintic but mostly effective against ascaris (worms). It contains carbobydrate, lavonoids, tannins, protein and sterols, it tastes sweet and sour [7]. The purple mombin (Spondias purpurea L.) is stewed whole, with sugar, and consumed as dessert [8], and can be preserved for future use merely by boiling and drying, which keeps the fruit in good condition for several months [8]. In Florida, yellow mombin is sold in local markets and consumed fresh; and it makes a signi icant contribution to the diet of people in local areas of the tropics when in season [7]. Data from various sources have identi ied increased consumption of the fruit of Spondias mombin as food in raw and processed form as a result of great taste (which ranges from sour to sour sweet), good levels of minerals, vitamins, low levels of lipids and reducing sugars [8][9][10][11][12]. Recent studies also suggest that the fruit of Spondias mombin is a rich source of antioxidants and phenols, minerals, phytonutrients, organic acids, phytosterols, terpenoids, and carotenoids [13][14][15]. Findings have established it as a potential source of highly nutritious feed stuff, folk medicine and phytomedicine as a result of its aromatic, astringent and refrigerant nature [8,13,[16][17][18]. The tree exudes gum used as glue; root and bark decoctions are used as purgatives and remedies for diarrhea, dysentery and haemorrhoids [8], while leaves extract have been reported to have anxiolytic [19], anathematic, sedative, antiepileptic and antipsychotic [16], hypoglycaemic [20], in vitro antioxidant [21], and antimicrobial effects [22].
Research efforts are being directed towards utilizing locally available raw materials in food and beverage formulation. Indigenous beverages have been developed with great success and these include zobo and kunnu zaki [23,24]. With increased awareness of the consumers of diet related health problems, the emphasis has been to reduce chemical addition in food formulation including beverage. In the last few decades, interest in scienti ic research has shifted to plant materials having nutraceutical properties [25]. Recently, emphasis has been placed on foods that are useful in the prevention and treatment of diseases. The native plants like sorghum stem sheath and Spondias mombin fruits are usually under-explored in spite of their enormous nutritional and medicinal bene its in many countries. Adetuyi, et al. [2] reported that sorghum stem sheath lacks vitamin C which is abundant in Spondias mombin fruits. So, it is essential to explore the potential of indigenous plants through the development of innovative functional drinks. The established data on the nutritional composition of Spondias mombin fruits is an indication that they have potential to be used as a food additive with multiple purposes [5]. Spondias mombin can also serve as a protein, antioxidants, and fatty acid, mineral and vitamin sources for drink formulation. Although considerable amount of literature exists on the nutrient composition of sorghum stem sheath, however, there is a dart of information about its enrichment with Spondias mombin extract. This study therefore seeks to investigate its possible proximate and nutrient compositions so as to unravel new information to improve health and nutrition (Plates 1,2).

Materials
Sorghum stem sheath was purchased from Oja-oba market in Akure, Ondo State, Nigeria while Spondias mombin (iyeye) fruits were collected from a local farm in Akure, Ondo State. All chemicals used for analyses were of analytical grade. These chemicals were procured from Fisher Scienti ic (Oakville, ON, Canada) and Sigma Chemicals (St. Louis, MO).

Methods
Production of Spondias mombin extract: The method described by Tiburski, et al. [14], was adapted with some modi ications. About 200 g of Spondias mombin fruits were sorted and washed to remove extraneous materials. The pulps were extracted with 3000 ml of water manually by hand and sieved with a clean muslin cloth. The liquid extract was decanted into sterilized bottles and kept in a refrigerator for further use.
Production of sorghum stem-sheath-Spondias mombin extract: The method described by Adetuyi, et al. [2] was adapted with some modi ications. Dried sorghum stem sheath was freed from extraneous materials by manual sorting and winnowing. About 400 g of the stem sheath was weighed and washed slightly with water. The washed stem sheath was boiled thoroughly in 6000 ml of water for 30 mins to aid the extraction as well as destruction of heat sensitive micro-organisms present. It was then iltered into previously sterilized bowl using a clean muslin cloth to obtain sorghum stem drink. Spondias mombin extract was added at different concentrations [0, 5, 10 and 15% (v/v)] for enrichment. Each sample was stirred and boiled for 5 mins to prevent post production contamination. The samples were bottled immediately, pasteurized at 70 0 C for 15 mins, cooled slowly under running water and stored at ambient temperature (27 ± 2 0 C). Sorghum stem sheath -Spondias mombin extract and sample designation is shown in table 1.

Proximate analysis of sorghum stem sheath-Spondias mombin extract
The samples were analyzed for moisture content, crude fat, crude protein, ash content, crude ibre based on the method of analysis of the association of of icial analytical chemists [26]. Carbohydrate content was calculated by difference.

Mineral element and vitamin C analysis of sorghum stem sheath-Spondias mombin extract
The analysis for essential mineral elements was carried out by atomic absorption spectrophotometric using the method of Fashakin, et al. [27]. Ascorbic acid concentration in the enriched drink was determined using the method of Hassan and Hassan [28].

Determination of anti-nutritional constituents of sorghum stem sheath-Spondias mombin extract
Oxalate content was determined using the method of Edet, et al. [29]. Tannin was determined according to the modi ied vanillin -hydrochloric acid (MV -HCl) method of Price, et al. [30]. Saponin was determined according to the spectrophotometric method of Brunner [31].

Statistical analysis
All data were subjected to one-way Analysis of Variance and means were separated using Duncan's multiple range tests using SPSS for Windows version 16. The low chart for the production of sorghum stem sheath-Spondias mombin drink is shown in igure 1.

Proximate compositions (%) of sorghum stem sheath-Spondias mombin extract
The proximate composition of the sorghum stem sheath -Spondias mombin extracts are presented in table 2. This showed increases in crude fat, ash, protein and moisture content with decrease in carbohydrate content of the enriched extract. The moisture content of the enriched sorghum stem sheath increased insigni icantly (p > 0.05) from (87.71% to 87.01%) with increased inclusion of Spondias mombin extract. The moisture content of the stem sheath (88.00%) was relatively lower than other recorded values like Moringa oleifera extract (90.00%) [32]. The high moisture content of enriched samples may be due to high amount of water used for the extraction which underpins its role as thirst quenching characteristics [33,34].
The ash content increased insigni icantly (p > 0.05) from (0.34% to 0.42%) with increased inclusion of Spondias mombin extract. The ash content of the stem sheath (0.30%) was relatively higher than Moringa oleifera extract (0.20%) [35]. The ash in food determines largely the extent of mineral matters likely to be found in the food substance which nutritionally aids the metabolism of other organic compounds, such as protein and fat [36]. Plant materials are known to be rich sources of mineral elements. Ashing is usually carried out in order to evaluate the mineral matter of food [37].
The fat content increased insigni icantly (p > 0.05) from (0.109% to 0.340%) with increased inclusion of Spondias mombin extract. The fat content of the stem sheath (0.009%) was relatively lower than other recorded values like Piliostigma thonningii extract (1.42%) [38]. However, the lower amount of fat (0.109% to 0.340%) in the samples can be used as diet drink and preventive measures for other chronic diseases [39]. The koronye and Ngoddy [40] reported that fat should be less than 5% in juices and drinks since this could  result to rancidity leading to the development of unpleasant and odorous compounds.
Carbohydrate content of the enriched samples was obtained by difference which decreased insigni icantly (p < 0.05) from (11.46% to 10.99% ) with increased inclusion of Spondias mombin extract. The total carbohydrate of the stem extract (11.64%) content is lower than Cola millenii extract (37.8%) [14], Annona muricata extract (47.1%) [44] and Adasonia digitata extract (52.5%) [42]. The stem samples submits as potential source of carbohydrates that could be used as a good supplement to the scarce cereal grains in Nigeria as sources of energy in diet.

Mineral compositions (mg/100 ml) of sorghum stem sheath-Spondias mombin extracts
The mineral compositions of sorghum stem sheath-Spondias mombin extract are shown in table 3. The calcium contents of the enriched samples decreased insigni icantly (p < 0.05) from (601.99 to 526.97) mg/100 ml with increased inclusion of Spondias mombin extract. The calcium content of the stem sheath (632.00) mg/100 ml was signi icantly higher when compared with Moringa oleifera leaf extract (84.73) mg/100 ml [32], Piliostigma thonningii extract (43.11 mg/10 ml) [38], Lophira lanceolata extract (30 mg/100 ml) [45]. Sesemum indicum extract (281 mg/100ml) [43] and Cola millenii extract (168.35 mg/100 ml) [46]. The increased Ca content suggests that the enriched extract may be useful for the transport of oxygen and cellular activity. The Recommended Daily Allowance (RDA) ranged between 400 and 1200 mg per day for infants, children and young adults [47]. Consumption of the enriched samples will de initely contribute to the RDA of calcium in infants and adults and enhance the health status of the consumers. Functions of calcium include bone mineralization, muscle contraction, cell signaling and regulation of cell metabolism. It can also mediate the death of a cell or a group of cells [47].
The sodium contents of sorghum stem sheath-Spondias mombin extract decreased insigni icantly (p < 0.05) from (761.01 to 713.50) mg/100 ml with increased inclusion of Spondias mombin extract. The sodium content of the stem sheath (780.00) mg/100 ml was relatively higher than Moringa Oleifera extract (40.10 mg/100 ml) [35]. Sodium intake in the enriched drink may activate, the Na + /K + pump. This may cause in lux of K + into the intracellular luids and ef lux of Na + , accompanied with Cland water, thereby resulting in possible reduction in blood pressure. This could account for the acclaimed diuretic effect and consequently the antihypertensive effects of sorghum stem sheath extract as claimed by Adedayo, et al. and Awika, et al. [48,49].
The potassium contents of sorghum stem sheath-Spondias mombin extract ranged from 130.39 to 148.77 mg/100 ml which increased insigni icantly (p > 0.05) with increased inclusion of Spondias mombin extract to sorghum stem sheath extract. The potassium content of the stem sheath (123.04) mg/100 ml was relatively higher than Moringa Oleifera extract (178.24 mg/100 ml) [35]. Therefore, Spondias mombin extract is a potassium rich product. The increasing trend observed in this study also suggests that both Spondias mombin and sorghum stem sheath are good sources of mineral elements. Potassium is the principal intracellular cation of most body tissues [36]. Potassium rich diet is used therapeutically in patients with uncomplicated essential hypertension. Natural potassium sources such as food and drinks are used for treatment or supplement [54]. The results suggest that Spondias mombin could be a good source of calcium, magnesium, iron, where intakes of 150 -1000 g, 160-850 g, 8-32 g would meet the Adequate Intake (AI) and Recommended Dietary Allowance for these minerals respectively [55].
The vitamin C contents of the enriched samples are shown in table 3 which increased insigni icantly (p > 0.05) from (0.00 to 5.19%) with increased inclusion of Spondias mombin extract. The vitamin C content of the stem sheath (0.00) mg/100 ml was relatively lower than Moringa Oleifera extract (4.43 mg/100 ml) [35]. Lack of vitamin C in the stem sheath is in agreement with the report of USDA Nutrient data base [56] that sorghum stem sheath does not contain vitamin C. Gbadegesin, et al. [57] reported that the vitamin C status of beverages (such as zobo) can be improved by blending with plant materials and fruits. Adetuyi, et al. [2] obtained a similar result for vitamin C content of sorghum stem sheath extract (0.00%) when forti ied with 50%, 60%, 70%, 80% and 90% orange and pineapple juices and reported proportionate values of 0.7, 1.3, 2.1, 2.8 and 3.5 mg/100 ml and (0.5, 0.9, 1.2, 1.7 and 2.1) mg/100 ml in the vitamin C content of the blends, respectively. Vitamin C is a powerful water-soluble antioxidant that boosts the immune system and helps prevent cancer and heart disease [58]. Vitamin C requirements may be higher in stressed or traumatized persons or in persons with diabetes mellitus [52]. The RDA ranged between 30 to 60 mg per day for infants, children and adults. Consumption of the enriched drink will help provide some of the needed nutrients to meet the Recommended Daily Intake (RDI).

Anti-nutrient composition (mg/100 ml) of sorghum stem sheath-Spondias mombin extract
The result for the anti-nutrients composition of sorghum stem sheath-Spondias mombin samples is represented in table 4. Moderate levels of tannin were also found to be present in the enriched samples (0.025) mg/100 ml which is within the safe level (5.6 mg/day) [59]. A tannin content up to 5.6 mg is allowed in foods, and the intake of tannins present in the sorghum stem sheath extract (0.025) mg/100 ml was found to be much lower than that of zobo drink 0.035 mg/100 ml [60] and Moringa Oleifera extract (0.3410 mg/100 ml) [32]. The tannin content of the enriched extracts ranged between (0.144 and 0.442) mg/100 ml which increased insigni icantly (p > 0.05) with increased inclusion of Spondias mombin extract. The levels of this tested anti-nutrient in the enriched samples were very low and within the tolerable (safe) levels for man (5.60 mg/day) [61].
The oxalate content of the enriched stem samples (0.303 and 0.385) mg/100 ml which increased insigni icantly (p > 0.05) with increased inclusion of Spondias mombin extract was within the safe level of consumption in humans since the lowest lethal dose reported is 5 g (about 70 mg/kg) [62] and so therefore 40 -50 mg/day is recommended [63]. The oxalate content of the stem sheath (0.220) mg/100 ml was relatively lower than Moringa Oleifera extract (3.3 10mg/100 ml) [32]. Mubarak, and Fasoyiro [64,65] reported that processing techniques could inactivate some food enzymes and degrade the anti-nutrients by leaching the toxic component into hot water. Albihn and Salvage [66] reported that boiling may cause considerable skin (epidermal) rupture and facilitate the leakage of soluble oxalate into boiling water. The levels of this tested anti-nutrient in the enriched samples were low and within the tolerable (safe) levels for man (10 mg/day) [59]. The saponin level of the sorghum stem sheath -Spondias mombin extract ranged between (0.070-0.198) mg/100 ml which increased insigni icantly (p > 0.05) with increased inclusion of Spondias mombin extract. The saponin content of the stem sheath (0.018) mg/100 ml was relatively lower than Moringa Oleifera extract (2.500 mg/100 ml) [32]. Saponins have been found to cause haemolytic activity by reacting with the sterols of erythrocytes membrane [61]. The levels of this tested antinutrient in the enriched samples were low and within the tolerable (safe) levels for man which may not constitute any health hazard or mal-absorption of other nutrients when taken in large quantity (10 mg/ day) [59].

Conclusion
Data indicated higher nutritional compositions with low concentrations of anti-nutrients within consumable safe limits. This shows that the enriched samples can be potential sources of nutrients.

Recommendation
The physicochemical and antioxidant properties of the enriched samples could be studied for further research work.
Also, the shelf life of the extract under different preservative techniques could be evaluated.