Main Article Content
This study investigated the effect of heat treatment and duration on yield and qualities of Walnut (Plukenetia conophorum) oil. The experimental design was carried out using the central composite rotatable design (CCRD) of response surface methodology with a total of thirteen experimental runs. The process variables and their ranges were roasting temperature 87.57ºC to 172.43ºC and roasting duration 10 min to 46.21 min. Oil from each experimental run was extracted using Piteba screw oil expeller. The expressed oil yield was determined and the results revealed that the oil yield ranged from 33.87% to 30.67% for the maximum and minimum values which were achieved at temperatures and duration of 172.43% at 25 min and 87.57ºC at 25 min respectively. Optimum process condition was achieved at roasting temperature and duration of 160ºC and 40 min with two possible solutions of 0.82 desirability which gave oil yield (33.50%); peroxide value (7.8 MeqO2/g); colour (13.69 mg/L); free fatty acid (1.46%) and iodine value (136.82 mmol/100 g). The low free fatty acid and peroxide values in walnut oil is an indication of its overall quality thus its suitability as an alternative oil to supplement existing edible oils.
Bachman, J. Oilseeds processing for small scale producers. National Center for Appropriate Technology (NCAT), Agriculture Specialist. USA; 2004.
Akinoso R. Effect of moisture content, roasting duration and temperature on yield and quality of palm kernel (Elaeis guineensis) and sesame (Sesamum indicum) oils. Ph.D Thesis. Department of Agriculture and Environmental Engineering. University of Ibadan, Nigeria; 2006.
O’Brien O. Fats and Oils formulating and processing for application. Technical Publishing Company Inc. Laacoster, USA; 2008.
Chijioke OC, Anosike C, Ani CC. Studies on the phytochemical and nutritional properties of Tetracarpidium conophorum (black walnut) seeds. Journal of Global Bioscience. 2015;4(2):1366-1372.
Kanu AM, kalu JE, Okorie AC, Fox NJ, Stachowiak GW. Vegetable oil-based lubricant a review of oxidation. Tribology International. 2007;40(7):1035–1046.
Savage GP. Chemical composition of walnuts (Juglans regia L.) grown in New Zealand. Plants for Human Nutrition. 2001; (56)1:75
Segura R, Javierre C, Lizarraga MA, Ros E. Other relevant components of nuts, phytosterols, folate and minerals. British Journal of Nutrition. 2006;(96):S36–S44.
US. Department of Agriculture, Agricultural Research Service. USDA National Nutrient Database for Standard Reference; 2008
Ostlund RE. Phytosterols in Human Nutrition. Annual Review of Nutrition. 2002; (22):533–549.
Abbey M, Noaks M, Belling GB, Nestel PJ. Partial replacement of saturated fatty acids with almonds or walnuts lowers total plasma cholesterol and low-density-lipoprotein cholesterol. Am. J. Clin. Nutr. 1994;59(995-999).
Torabian S, Haddad E, Cordero-MacIntyre Z, Tanzman J, Fernandez ML, Sabate J. Long-term walnut supplementation without dietary advice induces favorable serum lipid changes in free-living individuals. Eur J Clin Nutr. 2010;64:274–279.
FAO. The state of Food and Agriculture. Food and Agriculture Organization of the United Nations Rome; 2005.
Arinola SO, Ogunbusola EM. Physicochemical characteristics and the effect of packaging materials on the storage stability of selected Curcurbits Oils. American Journal of Food and Nutrition. 2013;(13):34-37.
Enujiugha VN, Ayodele-Oni O. Evaluation of nutrients and antinutrients in lesser known under-utilized oil seeds. International. Journal of Food Science and Technology. 2003;(38):525-528.
Edem CA, Dosunmu MI, Bassey FI. Determination of proximate composition, ascorbic acid and heavy metal content of African Walnut (Tetracarpidium conophorum). Pakistan Journal of Nutrition. 2009;(8):225-26.
Akinoso R, Igbeka JC, Olayanju Bankole TMAK. Modelling of oil expression from palm kernel (Elaeis guineensis Jacq) Agricultural Engineering International – The CIGR E Journal. 2006;8:1-8.
Montgomery DC. Design and Analysis of Experiments: Response surface method and designs. John Wiley and Sons, Inc. New Jersey, USA; 2005.
Popoola YY, Akinoso R, Raji AO. Optimization of oil extraction from giant bushel Gourd seeds using response surface methdology. Food and Nutrition Science. 2016;1–8.
AOAC. Official Methods of Analysis, 18th edition, Association of Official Analytical Chemists, Gaithersburg, MD, USA; 2007.
AOCS. Official methods and recommended practices of the american oil chemists society. American Oil Chemists. Society, Champaign, USA. 1997
AOAC. Association of Official Analytical Chemists Official Methods of Analysis Chemists. 15th edition; 1997.
Wilfred S, Adubofuor J. Oldham JH. Department of Hotel, Catering and Institutional management, Kumasi Polytechnic, Kumasi, Ghana; 2010.
De Lucas A, Rineon J, Gracia I. Influenced of operating variables on yield and quality parameters of olive Husk oil extracted with supercritical carbon dioxide. J. Am. Oil Chem. Soc. 2002;237-243.
Ottai M, Abdel‐Moniem A, El‐Mer‐gawi RA. Effect of variety and location on growth and yield components of Roselle, Hibiscus sabdariffa L. and its infestation with the spiny bollworm eariasinsulana (Boisduval). Arch. Phytopathol. Plant Prot. 2004; (37):215–231.
Akinoso R, Aboaba SA, Olajide WO. Optimization of roasting temperature and time during oil extraction from orange (citrus sinensis) seeds: A Response surface methodology approach. african Journal of Food, Agriculture, Nutrition and Development. 2011;11(6):1-18.
FAO/WHO. Report of the 21st session of the Codex Alimentarius Committee on fats and oils. Kola Kinabalu, Malaysia; 2009.
Ogbunugafor HA, Eneh FU, Ozumba AN, Igwo-Ezikpe MN, Igwilo IO, Adenekan SO, Onyekwelu OA. Physico-chemical and antioxidant properties of Moringa oleifera seed oil. Pakistan Journal of Nutrition. 2011;10(5):409-414.
Nzikou JM, Mvoula-Tsieri M, Matouba E, Ngakegni-Limbili AC, Linder M, Desobry S. Solanumnigrum L. seeds as an alternative source of edible lipids and nutriment in Congoi brazzaville. Journal of Applied Science. 2007;7.
Asuquo JE. Studies on the adsorption of some selected metallic soaps onto Hematite. Ph.D. dissertation, University of Port Harcourt, Nigeria; 2008.
Salunkhe DK, Chava JK, Adsuk RN, Kadam S. World Oilseed: Chemistry, Technology utilization. Van Nostrand Reinhold, New York;1992.
Soetaredjo FE, Budijanto GM, Prasetyo RI. Indraswati N. Effects of pre-treatment condition on the yield and quality of neem oil obtained by mechanical pressing. ARPN Journal of Engineering and Applied Sciences. 2008;3(5):45-49,1819-6608.
Fox NJ, Stachowiak GW. Vegetable oil-based lubricants &– A review of oxidation. Tribology International. 2007;40(7):1035–1046.
Orhevba BA. Adebayo SE, Nwankwo CC. Determination of some engineering properties of dika nut (Irvingia gabonensis) at two moisture content levels as relevant to its processing. International Journal of Engineering Research and Applications. 2013;3(2):182-188.
FAO/WHO. Codex Alimentarius Commission: Fats, Oils and Related Product. 1993;8.
SON Standard Organization of Nigeria, Standards for Edible Refined Palm Oil and its Processed form; 2000.
Zubr J. Oil seed crop: Camelina sativa. Ind. Crop Prod. 1997;6:113–119.
Ajayi IA. Physicochemical attributes of soils from seeds of different plants in Nigeria. Bull. F. Chem. Soc. Ethiopia. 2010;24:145–149.
Akubugwo EI, Chinyere, Ugbogu GC. Physicochemical studies of extracts from plant seeds in nigeria. Pak. J. Nutr. 2008; (7):570-573.
Ullah J, Hamayoun M, Ahmad T, Ayub M. Zafarullah. Effect of light, natural and synthetic antioxidation on stability of edible oils and fats. Asian J Plant Sci. 2003;(2): 1192–1194.
Akinoso R, Raji AO. Optimization of oil extraction from locust bean using response surface methodology. European Journal of Lipid Science and Technology. 2011;113: 245-252.