Isolation and characterization of lactic acid bacteria from locally fermented milk

ABSTRACT Nunu is a spontaneously fermented yoghurt-like milk product consumed as a staple food commodity invirtually all parts of the Country. Its production and consumption gives way to much food security and economic benefits to the rural people. However, the process characteristics result in products which are not appealing to many people, have very short shelf-life and could have food safety concerns. In a framework of research to improve the product quality and increase consumption, a study was conducted to determine the process characteristics and elucidate the predominant microflora associate with the production of the product. A survey was done on the technology of nunu production in three major towns of the in the Country, during which fermenting nunu were taken from 5 processors for laboratory analysis. pH, and titratable acidity were determined, as well as isolation and identification of the predominant microorganisms. They were characterized based on colony morphology, cell morphology and biochemical tests.Processing of nunu in Nigeria takes place at ambient conditions in calabashes or plastic containers, and spontaneously. No pre-fermentation heating of the milk is done. The duration of fermentation is 24 to 48 hours. Several species of Lactic acid bacteria were isolated from the fermenting samples, they are classified as lactobacillus, Leuconostoc, Lactococcus, Pediococcus, Enterococcus, and Streptococcus; . The fermentation of nunu is spontaneous. Potential pathogens may be present in the milk fermented, but are eliminated as the fermentation progresses to 48 hours, increasing the safetyof  the product.The presence of LAB in foods can cause shelf life elongation and safety of the food products.
TABLE OF CONTENT
CHAPTER 1INTRODUCTION
CHAPTER 2REVIEW OF LITERATURE2.1. Lactic acid bacteria2.2. Probiotics2.3. Antimicrobial peptide Bacteriocin produced by lactic acid bacteria2.3.1. Bacteriocin produced by Streptococcus sp.2.3.2. Bacteriocins produced by Enterococcus faecium2.3.3. Bacteriocins produced by Lactobacillus plantarum2.4. Probiotics in aquaculture2.5. Indian traditional fermented foods as source of lactic acid bacteria2.5.1. Cereal based (with/without pulses) fermented foods2.5.2. Cereal/pulse and butter milk based fermented food2.5.4. Milk based fermented foods2.5.5. Vegetable, bamboo shoot and unripe fruits based fermented foods2.5.6. Meat based fermented foods2.5.7. Pulse based fermented foods2.6. Adherence of lactic acid bacteria to intestinal cell line and inhibition of pathogen adherence2.7. Protective Roles of Probiotics on Colon Cancer
CHAPTER 3 3.0MATERIALS AND METHODS3.1 Samples and Sample collection3.2 Determinations of pH and Titratable acidity. 3.3 Enumeration and Isolation of Microorganisms3.4 Phenotypic characterization3.5 Characterization of Lactic acid bacteria3.6Identification of lactic acid bacteria at the genus level3.7 Identification of lactic acid bacteria to the species level
CHAPTER 44.0 RESULTS 4.1 DISCUSSION
CHAPTER 55.0 CONCLUSIONS/FINDINGSREFERENCES