International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 09 Issue: 02 | Feb 2022 www.irjet.net p-ISSN: 2395-0072 © 2022, IRJET | Impact Factor value: 7.529 | ISO 9001:2008 Certified Journal | Page 295 Effects of Pretreatments and Drying Methods on Some Anti-nutrients and Proximate Composition of Peanut (Arachis Hypogaea) Christopher J. Etti 1 , Linus Ashiwel Adie 2 1,2 Department of Agricultural and Food Engineering, Faculty of Engineering, University of Uyo, Uyo, Akwa Ibom State, Nigeria ---------------------------------------------------------------------***---------------------------------------------------------------------- Abstract - In this study, the fresh peanuts were dehydrated by microwave hot air drying and conventional hot air oven drying methods. The samples were dried at three different temperatures: 50, 60, and 70 o C, with and without the application of pretreatment by soaking in water and in brine. The effect of the pretreatment and drying processes were tested on some of the anti-nutrients (oxalate and tannin), and proximate composition of the peanuts. The average value for oxalate and tannin were 24.58% and 5.27% respectively for the raw samples. Pretreatment and microwave drying was proven to have the highest effect on the anti-nutrients by reducing the oxalate from 24.58% to 2.08% when pretreated in brine and dried at 70 o C; and the tannin was also reduced from 5.27% to 3.33% when water soaked and microwave dried at 70 o C. This shows that pretreatment by soaking in brine or water reduced the anti-nutritional factor of peanut which in turn influenced the proximate compositions of the peanuts. Key Words: Temperature, Pretreatments, Anti-nutrients, Nutrients, Peanut 1. INTRODUCTION Peanuts (Arachis hypogaea), which is also referred to as groundnuts in certain places of the world are edible leguminous seeds. India and Nigeria are the second and third principal producer of peanuts respectively in the whole world, with total production capacity of approximately 6.857 million metric tons and 3.029 million metric tons respectively per year [1]. Arachis hypogaea (A. hypogaea) is also regarded as pea from the family (fabaceae) of bean/legume. Even though A. hypogaea is a leguminous crop; it is commonly considered as oilseeds because of its great oil content. A. hypogaea is a rich source of oil, protein and fibers [2]. Aside the production of oil, A. hypogaea can be used for peanut butter manufacturing, production of confectioneries and roasted peanuts, manufacturing of Snack products, meat product formulation extenders and for making of soups and desserts. There are so many A. hypogaea cultivars presently. Some A. hypogaea varieties are favoured over others because their specific usages due to their differences in flavour, percentage oil content, variation in their size and shape, and their ability to resist diseases infection. There are many different cultivars which are used interchangeably however, the most popular cultivars are Spanish, Runner, Virginia and Valencia. Most A. hypogaea sold are done in their shell and are mostly of the Virginia type with some Valencias breed chosen due to their largeness in size and the eye-catching appearance of their shell. Spanish A. hypogaea are commonly used for production of candy, salted nuts, and butter. Some Runner varieties are also used to manufacture peanut butter [3]. The consumption of A. hypogaea globally are in various forms, principally as traditional cuisine. They are utilised as the comprehensive source of dietary basis for people on tours to various areas like Antarctica, space and trekking. It has notably been the source of elimination of malnutrition amongst the population in many African countries in the recent years [4]. Anti-nutrients are substances found in most food substances which are Poisonous to humans or in some ways limit the nutrient availability to the body. Plants evolve these substances to protect themselves and to prevent them from being eaten. However, if the diet is not varied, some of these toxins build up in the body to harmful levels [5]. Some vitamins in food may be destroyed by anti-nutritional substances. Legume family is one of the most important families in plant kingdom, in which it is a cheap protein source for vegetarian diets [6]. The Presence of anti- nutritional factors, such as flatulence factors, phytic acid and enzyme inhibitor limit the use of leguminous crops in food industry. There are diverse anti-nutrients domiciled in various fragments of A. hypogaea, such as peanut hull, skin, seed, kernel, root and cotyledons [7]. The presence of lectins in A. hypogaea causes broad interference with absorption of nutrients across intestinal wall. Lectins also known as hemagglutinin, is a plant agglutinin that exerts specific affinity for certain sugar molecules [8]. Ramakrishna et al. [6] reported the presence of trypsin inhibitors inhibiting the activities of protease, such as plasmin, chymotrypsin and trypsin. Pahnwar [9] revealed the presence of phytates, oxalates, tannins, aflatoxin, oligosaccharides and hydrogen cyanide in peanuts and their effects on health. Goitrogens is a naturally occurring compound that is present in groundnut that suppresses the function of thyroid gland [8]. It interferes the uptake of iodine, which in turn causes the enlargement of thyroid gland. The phenomenon is known as “goitre”. Salunkhe [8] also found Peanut I in groundnuts. Peanut I is a peanut protein that acts as an allergic factor in inducing peanut allergy in certain individuals. The other anti-nutrients that are present in groundnut include phenolic compounds, flatus agent, bitter flavour compounds and phytate. This study investigates the presence of some anti-nutritional factors