Determination of the Nutrients, Anti-Nutrients and Functional Properties of Processed Cocoyam (Xanthosoma sagittifolium) Cultivars Grown in Southeast, Nigeria

Abstract

This project determined the nutrients, anti-nutrients and functional properties of two cultivars of processed (boiled and fermented) Xanthosoma sagittifolium (ede ocha and ede uhie) flours grown in Southern, Nigeria. The proximate, minerals, chemical, anti-nutrients and functional properties of the cocoyam flours varied significantly (P<0.05). The results showed that the moisture content varied from 6.17% to 7.88%, with ede uhie exhibiting higher values. The same trend was observed in crude protein (4.33-5.92%), crude fiber (1.04-1.94%), crude fat (1.16-3.22%), ash (2.17-2.93%), with ede uhie exhibiting higher values than ede ocha. However, the carbohydrate and energy values were higher in ede ocha. For the mineral contents, the range values were: Ca (10.2341.17mg/100g), Na (15.22-17.66mg/100g), Mg (5.82-8.38mg/100g), P (12.31-16.19mg/100g), K (2.78-3.62mg/100g), with ede uhie showing higher values. On pH, TTA, starch and total sugar, it was observed that fermented ede ocha had higher pH value (6.82), TTA was higher in fermented ede ocha (0.92%), starch (24.66%) and total sugar (3.29%) values were higher in raw ede ocha than others. Anti-nutrient factors were generously reduced by processing methods especially boiling by between 50-100%, and fermentation by between 5-77% in most of the parameters analyzed. Functional properties ranged from BD (0.60-0.81g/mL), WAC (2.19-2.71g/mL), OAC (1.452.92g/mL), FC (16.38-19.52g/mL), FS (1.96-2.48 min/sec) and GT (60.85-81.05 C). While BD, WAC, OAC, FC were higher in the ede ocha flour, FS and GT were higher in ede uhie flour. Relating the physicochemical and functional properties, ede ocha has a potential for a quality food thickener. Overall, the results obtained in this study can be used to develop cocoyam food based products for enhanced nutrition with a potential to promote cocoyam commercial agriculture and composite utilization for confectionary industries in Nigeria. Introduction Cocoyam (Xanthosoma sagittifolium (L.) Schott) is one of the important specie of edible aroids, grown as subsistence staple in tropical and sub-tropical countries. They are grown primarily for their edible starch laden corms and cormels, and their leaves are used as vegetable [1], and in wrapping of grated cocoyam (Xanthosoma spp.) or water yam (Dioscorea alata) for Ekpang nkwukwo porridge, a local delicacy. According to Falade and Okafor [2], Nigeria is the largest producer of cocoyam in the world with an annual production of 3.450 million metric tonnes in 2012, representing 72.2 %, 57.7 % and 45.9 % of total production in West Africa, Africa and the World respectively. Cocoyam is a giant crop, which corms, cormels, leaves, stalks and inflorescence are utilized for food [3]. Odebunmi et al. [4] opined that Xanthosoma corms are rich sources of nutrients, namely, moisture (80.99 %), ash (1.03 %), crude protein (5.47 %), crude fat (0.20 %), crude fiber (1.28 %) and total carbohydrate of 11.03 %. The functional, pasting and granule size of cocoyam starches have been reported [2, 5, 6]. Cocoyam is a suitable food products, as a thickener and as food for people with gastro-intestinal disorders due to the starch digestibility (about 98 %), a quality attributed to its granule size which is ten times less than that of potato [7]. Cocoyam starches have great potential for industrial applications in textiles, pharmaceutical, paper Sustainable Food Production Submitted: 2017-11-07 ISSN: 2624-876X, Vol. 1, pp 11-21 Revised: 2018-01-20 doi:10.18052/www.scipress.com/SFP.1.11 Accepted: 2018-01-22 CC BY 4.0. Published by SciPress Ltd, Switzerland, 2018 Online: 2018-03-05 This paper is an open access paper published under the terms and conditions of the Creative Commons Attribution license (CC BY) (https://creativecommons.org/licenses/by/4.0) and food processing. However, cocoyam utilization has been limited due to a number of antinutritional and toxic factors, especially oxalates and phytates which imparts acrid taste, and causes sharp irritation and burning sensation in the throat and mouth on ingestion [8]. Among the local folks, Xanthosoma sagittifolium corms and cormels are boiled, roasted and eaten with palm oil and/or vegetable sauce. The corms can be pounded with cassava into fufu and served with soup. However, flour produced from Xanthosoma sagittifolium corms and cormels through adequate processing methods can be used for baked end products as a value addition to enhance the utilization of cocoyam Processing of fresh Xanthosoma sagittifolium corms and cormels into flours has another advantage of reducing its losses due to high water content and storage inadequacy, reduce transportation cost, increase versatility and utilization in food formulations [2]. Application of Xanthosoma sagittifolium flours in baking, soup and porridge is primarily governed by their functional and physicochemical properties. These are those properties that affect the physical and chemical attributes during food preparations [2]. Investigation of these properties was necessary to evaluate the requisite characteristics of Xanthosoma sagittifolium cultivars in order to enhance their food and industrial utilization. Several authors have reported on the functional, physicochemical, and pasting characteristics of cocoyam flours [2, 6, 7, 9, 10]. However, scarce information is available on the nutrients, anti-nutrients and functional properties and of processed cultivars of Xanthosoma sagittifolium flours. Therefore the objective of this research was to evaluate the nutrients, anti-nutrients and functional properties of processed (boiled and fermented) Xanthosoma sagittifolium cultivars (ede ocha (white) and ede uhie (red)) grown in Southeastern, Nigeria. Material and Method Raw materials Cultivars of Xanthosoma sagittifolium known as ede ocha (white) and ede Uhie (red) (Igbo language of Southeastern Nigeria) were procured from Umudike, Ikwuano Local Government Area, Abia State. There were identified by the University Herbarium, Michael Okpara University of Agriculture, Umudike, Nigeria. Umukike is situated between latitude 05°29N and longitude 07°33 E and 122m altitude. The soil is classified as acidic and sandy loam and characterized as an ultisol [11]. Sample preparation The samples was sorted, peeled, washed and cut into 2 cm slices and were divided into 3 equal parts of 500 grams for different processing treatments. Fermented Flour: Five hundred grams of the sliced samples was soaked in 1500 mL of water and allowed to ferment for 72 h after which the water was drained off, washed in clean water and oven dried at 55oC for 72 h. The fermented cocoyam chips was milled and sieved through 0.42 mm mesh size (Fig.1). Boiled Flour: Five hundred grams of the sliced samples was boiled in 1L of water for 15 min. at 100oC after which it was oven dried at 55oC for 72 h. The boiled chips was milled and sieved through a 0.42 mm mesh size (Fig.1). Flour Raw: Five hundred grams of the sliced cocoyam samples was oven dried at 55oC for 72 h. The chips was milled and sieved through a 0.42 mm mesh size (Fig. 1). 12 SFP Volume 1