EC Nutrition

Background: Whey, a major by‑product of cheese production, represents a significant environmental risk due to its high organic load. However, its richness in proteins, lactose, and minerals offers potential for both nutritional enrichment and sustainable ethanol production. This study evaluated the chemical and microbiological properties of whey protein from local cheese producers in Wad‑Medani, Sudan, and assessed its potential in ethanol synthesis using Kluyveromyces marxianus.

Materials and Methods: Whey samples from nine sites were analyzed for chemical composition and microbial load. Ethanol production potential was evaluated through fermentation and subsequent measurement of ethanol concentration, pH, density, and conductivity.

Results: Significant differences (P < 0.001) were found in moisture (62.8 - 91.0%), protein (3.46 - 6.03%), fat (1.06 - 5.13%), ash (2.35 - 26.70%), lactose (1.09 - 1.80%), sodium (6.13 - 7.33%), and potassium (3.33 - 5.23%). Microbial counts varied: total viable count ranged from 6.3 × 10³ to 4.5 × 10⁵ CFU/mL; lactic acid bacteria from 5.0 × 10² to 5.2 × 10³ CFU/mL; while E. coli, Salmonella spp., and Bacillus cereus were rarely detected. Ethanol yields were relatively low (1.07 - 1.16%) but consistent.

Conclusion: Sudanese whey protein demonstrated valuable nutritional composition and acceptable microbiological quality, making it a promising substrate for functional food and bioethanol production. To enhance ethanol yield and value recovery while reducing dairy waste, improved hygiene practices and optimized fermentation processes are strongly recommended.

 Keywords: Whey Protein; Ethanol Production; Cheese Whey; Kluyveromyces marxianus

1. Spălățelu C. “Sustainable valorization of whey in the food industry”. Innovative Romanian Food Biotechnology 10 (2012): 1-8.
2. Ozmihci S and Kargi F. “Ethanol production from cheese whey powder solution in a packed column bioreactor”. Biochemical Engineering Journal 2 (2008): 180-185.
3. Mohammadreza K., et al. “Comparison of ethanol production from cheese whey permeate by two yeast strains”. Journal of Food Science and Technology 5 (2012): 614-619.
4. Lorenzo P., et al. “Fermentation of lactose to ethanol in cheese whey permeate and concentrated permeate by engineered Escherichia coli”. BMC Biotechnology1 (2017): 48.
5. Official Methods of Analysis. 18^th edition. Washington DC: Association of Official Analytical Chemists (2005).
6. Lane JH and Eynon L. “Volumetric determination of reducing sugars by means of Fehling's solution with methylene blue as internal indicator”. Journal of the Society of Chemical Industry 42 (1923): 32-37.
7. Compendium of Methods for the Microbiological Examination of Foods. Washington DC: American Public Health Association (1967).
8. Marshall RT. “Standard Methods for the Examination of Dairy Products”. 16^th Washington DC: American Public Health Association (1993).
9. Kiss I. “Testing Methods in Food Microbiology: A Textbook”. New York: Elsevier (1984).
10. Rayman KN., et al. “Performance of four selective media for enumeration of Staphylococcus aureus in corned beef and in cheese”. Journal of Food Protection 2 (1988) 878-888.
11. Thatcher FS and Clark DS. “Microorganisms in Foods: Their Significance and Methods of Enumeration”. Buffalo, NY: University of Toronto Press (1968).
12. EN ISO. “Microbiology of food and animal feeding stuffs - Horizontal method for the enumeration of presumptive Bacillus cereus - Colony-count technique at 30°C”. Brussels: European Committee for Standardization (2004).
13. Bipasha D., et al. “Studies on production of ethanol from cheese whey using Kluyveromyces marxianus”. In: Proc Int Conf Advances in Bioprocess Engineering and Technology (ICABET) (2016): 1-5.
14. Bylund G. “Dairy Processing Handbook”. Tetra Pak Processing (2003).
15. Panesar PS., et al. “Bio-utilisation of whey for lactic acid production”. Food Chemistry 1 (2007): 1-14.
16. Smith K. “Current and future processing of whey ingredients”. Wisconsin Center for Dairy Research (2012).
17. Samia MAA., et al. “Microbiological and physicochemical properties of raw milk used for processing pasteurized milk in Blue Nile Dairy Company (Sudan)”. Australian Journal of Basic and Applied Sciences 3 (2009): 3433-3437.
18. Gadaga TH., et al. “Enumeration and identification of yeasts isolated from Zimbabwean traditional fermented milk”. International Dairy Journal 7 (2000): 459-466.
19. Biratu K and Seifu E. “Chemical composition and microbiological quality of Dhanaan: Traditional fermented camel milk produced in eastern Ethiopia”. International Food Research Journal 5 (2016): 2223-2228.
20. Hadrya F., et al. “Microbiological quality assessment of dairy products marketed in Rabat Salé Zemmour Zaer region in Morocco”. Cahiers de Nutrition et de Diététique 6 (2012): 303-307.
21. Ministère de l’Agriculture et du Développement Rural Ministère de la Santé Ministère de l’Industrie et du Commerce. Arrêté conjoint n°624 04 du 17 Safar 1425 (8 avril 2004) relatif aux normes microbiologiques des denrées animales ou d’origine animale.
22. Lucília D., et al. “Alcohol production from cheese whey permeate using genetically modified flocculent yeast cells”. Biotechnology and Bioengineering 5 (2001): 593-602.
23. Langford NJ., et al. “The lacing defence: double blind study of thresholds for detecting addition of ethanol to drinks”. British Medical Journal7225 (1999): 1610.
24. Hafij A., et al. “Demineralisation and recovery of whey proteins from commercial full-fat salty Cheddar whey using size-exclusion chromatography”. Food Chemistry 405 (2023): 134831.
25. Pasotti LS., et al. “Fermentation of lactose to ethanol in cheese whey permeate and concentrated permeate by engineered Escherichia coli”. BMC Biotechnology1 (2017): 48.