CHANGES IN THE QUALITY CHARACTERISTICS OF FERMENTING MOLASSES DURING LACTIC ACID PRODUCTION WITH Lactobacillus plantarum

ABSTRACT

Concerns over the microbial production of commercially valuable products have been growing as a result of escalating global energy and environmental problems. Of these, lactic acid has attracted a great deal of attention due to its widespread variety of applications, one of which is the production of polylactic acid (PLA), a biodegradable polymer which have several applications in a wide range of industries, thus, the need to produce lactic acid using inexpensive processes in order to reduce the cost of production of the acid. This study, showed a process for the production of lactic acid using cheap renewable resources such as the sugar molasses. The fermentation process was carried out at an initial temperature of 30°C and pH of 6.5 with molasses content of 9.5grams per litre. The process gave a lactic acid concentration of 1.98mg/100ml of lactic acid on the 5th day of fermentation with a decline to 1.44mg/100ml at the end of the 8 days fermentation process. There was also a high biomass yield of 3.15g/L with a steady decline in specific gravity and sugar content (% sucrose) from 24.9% to 2%. The use of molasses to produce value-added products such as Lactic acid bacteria biomass and lactic acid is feasible and successful and is a possible approach to the production of lactic acid with cheap resources, thereby reducing cost of production. 

Certification ﾿ iDedication ﾿ iiAcknowledgements ﾿ iiiTable of contents ﾿ ivList of tables ﾿ viiiList of figures ﾿ ixAbstract ﾿ xCHAPTER ONE ﾿ 11.0 ﾿ Introduction ﾿ 11.1 ﾿ Aims and Objectives ﾿ 3CHAPTER TWO ﾿ 42.0 ﾿ Literature Review ﾿ 42.1 ﾿ Lactic Acid ﾿ 42.1.1 ﾿ Uses of Lactic Acid ﾿ 82.2 ﾿ Lactic Acid Producing Organisms ﾿ 92.2.1 ﾿ Molds and Yeast ﾿ 112.2.2 ﾿ Bacteria ﾿ 122.3 ﾿ Raw Materials for Biotechnological Production of Lactic Acid ﾿ 182.4 ﾿ Production of Lactic Acid ﾿ 212.4.1 ﾿ Chemical Synthesis of Lactic Acid ﾿ 212.4.2 ﾿ Production of Lactic Acid by Fermentation Processes ﾿ 23CHAPTER THREE ﾿ 263.0 ﾿ Materials and Methods ﾿ 263.1 ﾿ Materials ﾿ 263.2 ﾿ Methods ﾿ 263.2.1 ﾿ Collection of sample ﾿ 263.2.2 ﾿ Preparation of Media ﾿ 263.2.2.1 ﾿ Test for Sterility of Prepared Media ﾿ 273.2.3 ﾿ Preparation of samples ﾿ 273.2.4 ﾿ Isolation of Lactobacillus plantarum From Vegetables ﾿ 273.2.5 ﾿ Characterization and Identification of Bacteria Isolates ﾿ 283.2.5.1 ﾿ Macroscopic examination ﾿ 283.2.5.2 ﾿ Microscopic examination ﾿ 283.2.5.3 ﾿ Biochemical tests ﾿ 303.2.5.4 ﾿ Sugar utilization test ﾿ 323.2.6 ﾿ Production of Sugar Molasses ﾿ 323.2.7 ﾿ Quality Characteristics of Molasses ﾿ 353.2.7.1 ﾿ Moisture ﾿ 353.2.7.2 ﾿ Ash ﾿ 363.2.7.3 ﾿ Nitrogenous substances ﾿ 363.2.7.4 ﾿ Sugar ﾿ 373.2.8 ﾿ Fermentation for Lactic Acid Production ﾿ 403.2.9 ﾿ Analysis of Fermentation Process ﾿ 403.2.9.1 ﾿ Determination of pH ﾿ 413.2.9.2 ﾿ Determination of Temperature ﾿ 413.2.9.3 ﾿ Determination of Specific Gravity ﾿ 413.2.9.4 ﾿ Determination of Total Titratable Acid (TTA) ﾿ 423.2.9.5 ﾿ Determination of Cell Biomass ﾿ 423.2.9.6 ﾿ Quantification of Lactic Acid Produced ﾿ 43CHAPTER FOUR ﾿ 444.0 ﾿ Results ﾿ 44CHAPTER FIVE ﾿ 565.0 ﾿ Discussion, Conclusion, Recommendation ﾿ 565.1 ﾿ Discussion ﾿ 565.2 ﾿ Conclusion ﾿ 575.3 ﾿ Recommendation ﾿ 58REFERENCESAPPENDIX
LIST OF TABLESTable ﾿      Title ﾿         Page1, ﾿ Physical Properties of Lactic Acid ﾿ 72, ﾿ Some Commercial Uses and Applications of Lactic Acid ﾿ 83, ﾿ Characteristics of Selected Bacteria, Molds and Yeasts of Interest in Lactic Acid Production ﾿ 104, ﾿ Characterization and identification of isolated Lactobacillus plantarum ﾿ 465, ﾿ Quality Characteristics of Molasses ﾿ 476, ﾿ Quantification of Lactic Acid Content ﾿ 48 ﾿
LIST OF FIGURESFigure ﾿ Title ﾿         Page1, ﾿ Sterioisomers of lactic acid; (a) L (+) Lactic acid (b) D (-) Lactic acid ﾿ 52, ﾿ Metabolic pathways for homofermentation and heterofermentation ﾿ 143, ﾿ Overview of the two manufacturing methods of lactic acid; (a) Chemical synthesis and (b) Microbial fermentation ﾿ 22 4, ﾿ Flow chart showing the production process of sugar molasses ﾿ 345, ﾿ Graph showing %Total Titratable Acid (TTA) produced during fermentation ﾿ 496, ﾿ Graph showing changes in specific gravity during fermentation ﾿ 507, ﾿ Graph showing fluctuations in temperature during fermentation ﾿ 518, ﾿ Graph showing changes in pH during fermentation ﾿ 529, ﾿ Graph showing increase in biomass during fermentation ﾿ 5310, ﾿ Graph showing decrease in sugar content (% sucrose) during fermentation ﾿ 5411, ﾿ Graph showing lactic acid content (mg/100ml) during fermentation ﾿ 55