Physicochemical and Microbiological Effect of Citric Acid Produced from Yam Peels and Aspergillus niger

Oluwatomisin Damilola Ojeyinka *

Department of Food Science and Technology, Faculty of Agriculture, Nnamdi Azikiwe University, PMB 5025, Awka, Anambra State, Nigeria.

Helen Obioma Agu

Department of Food Science and Technology, Faculty of Agriculture, Nnamdi Azikiwe University, PMB 5025, Awka, Anambra State, Nigeria.

Ngozi Eunice Odoh

Department of Food Science and Technology, Faculty of Agriculture, Nnamdi Azikiwe University, PMB 5025, Awka, Anambra State, Nigeria.

Izunna Tochukwu Ubaka

Department of Food Science and Technology, Faculty of Agriculture, Nnamdi Azikiwe University, PMB 5025, Awka, Anambra State, Nigeria.

*Author to whom correspondence should be addressed.


This work was aimed to study the physicochemical and preservative effects of citric acid produced from yam peels using Aspergillus niger. Fresh yam peels were washed, sundried and milled into flour, after which it was inoculated with Aspergillus niger in a nutrient medium and fermented for 6 days at 30℃. Citric acid was extracted from the fermented substrate (1200 mL) and total yield was 418 g of citric acid. Physico-chemical properties of the extracted and commercial citric acid were compared and the results were; pH (2.80 and 2.66), TTA (0.77% and 0.75%) and moisture content (2.40% and 1.8%) respectively. Appearance of both samples were crystalline with the extracted citric acid having a more off white colour. The preservative effects of commercial citric acid and extracted citric acid from yam peels were compared using face centered composite design. A 15 samples of fresh pasteurized watermelon juice were analyzed over a period of 7 days at room temperature with concentrations of 0.2– 0.5% per 100 mL of juice. Microbial analysis (TBC, TCC, and TFC) of citric acid was carried out. For extracted citric acid the results ranged from TBC (4.40c× 105  005 CFU/mL to 9.70 × 105  0.100 CFU/mL), TCC (no growth to 3.90 × 106  0.05 CFU/mL) and TFC (no growth to 9.70 × 105  0.100 CFU/mL).While for samples made with commercial citric acid the results ranged from; TBC (5.30 b × 105  0.001 to 2.65b × 106  005), TCC (no growth to 8.10 × 106  0.05 CFU/mL) and TFC (no growth to 2.21 × 106  0.105 CFU/mL). This implies that citric acid extracted from yam peels had better preservative effects compared to the commercially produced citric acid.

Keywords: Citric acid, Aspergillus niger, yam peel, physicochemical, microbiological effect

How to Cite

Ojeyinka , O. D., Agu , H. O., Odoh , N. E., & Ubaka , I. T. (2024). Physicochemical and Microbiological Effect of Citric Acid Produced from Yam Peels and Aspergillus niger. Asian Journal of Food Research and Nutrition, 3(1), 72–80. Retrieved from


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Kumar D, Jain VK, Shanker G, Srivastava A. Utilisation of Fruits Waste for Citric Acid Production by Solid State Fermentation. Process Biochemistry. 2003;38(12):1725-1729.

Hamdy HS. Citric acid production by Aspergillus niger grown on orange peel medium fortified with cane molasses. Annals of Microbiology. 2013;63 (1):267–278

Bikash CB. Citric acid from Aspergillus niger: A comprehensive overview. Critical Reviews in Microbiology. 2020;46(6):727-749.

Behera BC, Mishra R, Mohapatra S. Microbial citric acid: Production, properties, application, and future perspectives. Food Frontiers. 2021;2(1):62-76

FAO. Towards the Future we Want: End Hunger and Make the Transition to Sustainable Agricultural and Food Systems, Food and Agriculture Organization of the United Nations Rome; 2012.

Lakshmi MK, Shreya P, Murali MC, Prameela K. 27 - An emerging trend in waste management of COVID-19, Editor(s): Chaudhery Hussain, Subrata Hait, Advanced Organic Waste Management, Elsevier; 2022.

Oludumila OR, Abu TFA, Enujiugha VN, Sanni DM. Extraction, Purification and Characterization of Protease from Aspergillus Niger Isolated from Yam Peels. International Journal of Nutrition and Food Sciences. 2014;4(2):125-131.

Penniston KL, Nakada SY, Holmes RP, Assimos DG. Quantitative Assessment of Citric Acid in Lemon Juice, Lime Juice, and Commercially-Available Fruit Juice Products. Journal of Endourology. 2008;22 (3):567–570.

Soccol CR, Vandenberghe LPS, Rodrigues C, Pandey A. New perspectives for citric acid production and application. Food Technology and Biotechnology. 2006;44 (2):141–149.

Kamzolova SV, Morgunov IG, Aurich A, Perevoznikoa OA, Shishkanova NV, Stottmeister U, Finogenova TV. Lipase secretion and citric acid production in Yarrowialipolytica yeast grown on animal and vegetable fat. Food Technology and Biotechnology. 2005;2(43):113–122.

Thangavelu R, Murugaiyan K. An Experimental study on citric acid production by Aspergillus niger using gelidiellaacerosa as a substrate. Indian Journal of Microbiology. 2011;51(3):289-293

Nwosu FO, Kareem AO. Production of citric acid from lemon and cassava waste peels. Nigerian Journal of Materials Science and Engineering. 2015;6(1):1-7.

Torrado AM, Cortes S, Salgado JM, Max B, Rodriguez N, Bibbins B, Attilio C, Dominguez JM. Citric acid production from orange peel wastes by solid-state fermentation. Brazilian Journal of Microbiology. 2011;42(1):394–409.

Ruijter GJG, Van de Vondervoort PJI, Visser J. Oxalic acid production by Aspergillus niger: An oxalate-non-producing mutant produces citric acid at pH 5 and in the presence of manganese. Microbiology (Reading, England). 1999; 145(9):2569–2576.

Papanikolaou S, Dimou A, Fakas S, Diamantopoulou P, Philippoussis A, Galiotou-Panayotou M, Aggelis G. Biotechnological conversion of waste cooking olive oil into lipid-rich biomass using Aspergillus and Penicillium strains. Journal of applied microbiology. 2011;110 (5):1138-1150.

Schuster E, Dunn-Coleman N, Frisvad JC, Van Dijck PW. On the safety of Aspergillus niger-a review. Applied Microbiology and Biotechnology. 2002;59(4-5):426–435.

Onu CE, Nweke CN, Nwabanne JT. Modeling of thermo-chemical pretreatment of yam peel substrate for biogas energy production: RSM, ANN, and ANFIS comparative approach. Applied Surface Science Advances. 2022;11(1):100299.

Pau LS, Kehinde OO, Qi YS, Fitri AAZ, John CL, Tau CL. Overview of citric acid production from Aspergillus niger, Frontiers in Life Science. 2015;8(3):271-283.

Perwitasari U, Agustina NT, Pangestu R, Amanah S, Saputra H, Fahrourrozi AA, Juanssilfer AB, Thontwi A, Widyaningsih TD, Eris DD, Amaniyah M, Habibi MS. Cacao pod husk for citric acid production under solid state fermentation using response surface method. Biomass Conversion and Biorefnery. 2021;13(1): 7165–7173.

Amenaghawon AN, Omoruyi BO, Kenneth I, Okedi MO, Esenogho GO, Oyefolu PK, Muojama OE, Otuya IC, Eshiemogie SO, Okoh R, Anyalewechi CL. Biotechnological conversion of yam peels for enhanced citric acid production: Data-driven machine learning modeling and global sensitivity analysis of the impact of metabolic stimulants. Industrial Crops and Products. 2023;191(Part B):116022.

Marier JR, Boulet M. Direct determination of citric acid in milk with an improved pyridine-acetic anhydride method. Journal of Dairy Science. 1958;41(12):1683-1692.

AOAC. Official methods of analysis, Washington DC association of official analytical chemists 14th edition, Association of Analytical Chemists International, Arlington, Virginia, USA; 2010.

Agu KC, Chidozie CP. An improved slide culture technique for the microscopic identification of fungal species. International Journal of Trend in

Scientific Research and Development. 2021;6(1):243-254.

Noor R, Uddin MA, Haque MA, Munshi SK, Acharjee M, Rahman MM. Microbiological study of vendor and packed fruit juices locally available in Dhaka city, Bangladesh. International Food Research Journal. 2013;20(2):1011- 1015

Jabin T, Hossain MM, Nasrin S, Tabassum R, Rahman MA, Uddin M. Microbiological assessment and detection of drug resistant bacterial isolates in some vended fresh fruit juice samples in Dhaka city, Bangladesh. Food Research. 2022;6(7): 413-419.

Emirates Authority for Standardization and Metrology (ESMA) United Arab Emirates. Microbiological criteria for foodstuffs-Part I. Gulf Standard No. 1016/2000. U.A.E. Standard No. 1016/2002. Riyadh, Saudia Arabia: ESMA United Arab Emirates; 2000.

El-Saadony MT, Saad AM, Elakkad HA, El-Tahan AM, Alshahrani OA, Alshilawi MS, El-Sayed H, Amin SA, Ahmed AI. Flavoring and extending the shelf life of cucumber juice with aroma compounds-rich herbal extracts at 4 °C through controlling chemical and microbial fluctuations. Saudi Journal of Biological Sciences. 2022;29(1): 346-354.

Andres SC, Giannuzzi L, Zaritzky NE. The effect of temperature on microbial growth in apple cubes packed in film and preserved by use of orange juice. International Journal of Food Science and Technology. 2004;39(9):927–933

Lewis JE, Thompson P, Rao B, Kalavati C, Rajanna B. Human Bacteria in Street scale fruit juice processing. A Case Study of Visakhapatnam City, India: International Journal of Food Safety, Nutrition and Public Health. 2006;8(1):35-38