Thesis Abstract

<p>              <b>ABSTRACT</b></p><p>Groundnut seed roasting is a critical step in the processing for oil extraction, snack nuts, confectionaries and peanuts for roasting. Roasting enhances oil extraction processes as it reduces the oil’s viscosity, releases oil from intact cells and reduces the moisture content. A comparative performance evaluation of an existing and a modified groundnut seed roasting machines was carried out and reported in this study. A Completely Randomized Design (CRD) was used where roasting efficiency, percentage of groundnut seed loss and fuel consumption rate were used as performance indicators, for the two machines investigated (existing and modified machines). Two groundnut seeds varieties (Manipintar and ExDakar) and three turning speeds (30, 50 and 70 rpm) were used as independent variables. The combination of the independent variables resulted to a total of twelve (12) experimental treatments, thus with three replications carried out on each treatment a total of thirty-six (36) experiments were conducted. For the existing and modified roasting machine, results obtained revealed that 91.20% and 98.80%; 12.40% and 1.20%; and 1.90 kg/hr and 1.20 kg/hr were achieved as roasting efficiency; percentage of groundnut seed loss; and fuel consumption rate, respectively. It was established that the effects of using different roasting machine model and turning speeds are significant on roasting efficiency, while variety is not significant on roasting efficiency. For percentage of groundnut seed loss for the different machine models was highly significant, while variety and turning speed with their interaction are not significant. The interactions on the effects of using different machine model, variety of groundnut seed used and turning speed were highly significant on fuel consumption rate.&nbsp;</p><p><b>Keywords Roasting efficiency, percentage of seed loss, turning speed, groundnut, performance. </b> <br></p>

Thesis Overview

<p><b>1.0 INTRODUCTION</b></p><p><b>1.1 BACKGROUND STUDY</b></p><p>Groundnut, (Arachis hypogeal) also called peanut is a vital nutritional food in many developing countries. Among the agricultural products that are of great value to both man and animals is groundnut. It serves as raw material for industry. Groundnut oil also as vegetable oil for human consumption and groundnut seed cake is being used as part of ingredients in animal and poultry feeds. Groundnut is a protein rich legumes that grows well in semi-arid regions. There are two main types of groundnut: the America groundnut (Arachis hypogeal), and the African groundnut, the Bambara nut (voandzeia subterranean) (Ajao, et al., 2009; Hommons, 1994). Both are grown in western Africa as a protein source. Groundnuts also contain sufficient quantity of carbohydrates and fats. The America groundnut grow 30-40 cm high and do not spread. The West Africa groundnut is shorter and run along the ground from 30-60 cm high with a yields of kernels range from 0.5-40 tons/ha (Ajao, et al., 2009). In most developing countries, 80% of crops yields were around 1 tons/ha (Ajao, et al., 2009). The production of oil from groundnut entails a postharvest processing of groundnut which includes shelling, roasting and pressing (Mohammed and Hassan, 2012). Roasting is defined as the process of generating characteristics aroma, flavour and colour required by consumers for acceptance of such roasted food (Ola, et al., 2001). Roasting of food bring about thermal changes in the chemical components of relatively high temperature. This is accomplished by both using a hot air or small metal surface to heat up the material to the required temperature of which the material changes to required colour (Maduakoj, et al., 2006). During roasting, amino acids and carbohydrates react to produce tetrahydrofaran derivatives. Roasting also dries the peanuts further and changes its colour to brown as peanut oil stains the peanut cell walls (Ola, et al., 2001). Mohammed and Hassan, (2012) also reported that groundnuts roasting reduces moisture content and develops a pleasant flavour which makes the products more acceptable for consumption. Dry roasting represents the most significant form of processing in Nigeria. Among the problems in processing agricultural materials is that of roasting the seeds. Most oil seeds and nuts are roasted using heat to liquefy the oil in the crop cells and facilitate the release of oil during extraction that is you can roast peanut in the shell by spreading them on a shallow baking pan, one or two layers deep, and taking them into a 350o oven for 26 to 30 minute, turning them occasionally. The amount of oil produced will be much if it is properly roasted (Ajao, et al., 2009). Eke and Maigida, (1995) reported that excess heating during roasting results in low nutritional quality of protein. It also reduces the quantity of oil as well as it makes the colour of the oil extracted to be dark. Roasting of groundnut operation in Nigeria is mostly traditionally done using different pots such as clay pots, aluminium pot, on open fire until they are brown (Manta and Ajisegiri, 2007). This method is ineffective, time consuming and laborious. Olaniyan, (2010) also reported that roasting of groundnut and extraction of oil in Nigeria have been a serious issue in some rural parts of the country, where the roasting and the extraction of the oil are achieved by traditional method. Therefore, Manta and Ajisegiri, (2007) suggested the use of infrared heating in groundnut seed roasting operation to improve on the traditional techniques. Abdulsalam, (2013) developed a manually operated roasting machine that handled groundnut seed roasting operation more effectively than the traditional methods. Result revealed that the machine has the roasting efficiency of 66.2%. Lawan, (2015) modified the machine developed by Abdulsalam, (2013), in order to improve on its performance.&nbsp;</p><p>Therefore, this paper presents a comparative performance evaluation of the two (existing and modified) roasting machines to ascertain the level of improvement achieved.</p><p><b>Materials and Methods / Methodology</b>&nbsp;</p><p><b>Materials Used in the Study</b>&nbsp;</p><p>The following instruments and equipment were used during the conduct of this study;&nbsp;</p><p>i. Weighing balance,&nbsp;</p><p>ii. Stop watch,</p><p>&nbsp;iii. Existing and modified groundnut roasting machines,&nbsp;</p><p>iv. Charcoal,&nbsp;</p><p>v. Tachometer</p><p>&nbsp;vii. Moisture analyzer&nbsp;</p><p>viii. Thermometer Description of the Existing and the Modified Roasting Machines Description of the existing machine The machine has a handle as a driving mechanism, a drum roasting chamber of 0.066 m3 . The roaster is covered with circular trough at two ends which carry shafts onto this shaft are attached paddles for stirring the material being roasted and a handle for turning the shaft. The support consists of frame with covers on three sides. Apart from carrying the roasting chamber, it houses the heat source (charcoal burner) right below the roasting chamber for heating the drum. After accomplishing the roasting operation, an exit gate can be open which allows the roasted groundnut seeds out.&nbsp;</p><p>Plate 1 shows the existing roasting machine. Description of the modified roasting machine The modified roasting machine consists of a roasting chamber on top of the roaster stove, and a stirring shaft with blades attached inside the chamber can be operated manually by the crank handle attached. After accomplishing the roasting operation, an exit gate can be open which allows the roasted groundnut seeds out.&nbsp;</p><p>Plate 2 shows the modified roasting machine. Performance Evaluation of Groundnut Seed Roasting Machines Sample preparation A total of 100 kg of groundnut seeds, 50 kg each for the two varieties (Manipintar and Ex-Dakar) was used for the comparative analysis. Thereafter, dirt, foreign materials and immature seeds were removed (Plates 3 and 4). Moisture analyzer was used to determine the moisture content and found to be 2.34% and 2.51% dry basis for Manipintar (Mai Bargo) and Ex-Dakar, respectively. <br></p>