BACTERIOCINS IN FOOD PRESERVATION

ABSTRACT

Bacteriocins are antimicrobial protein or proteinaceous toxins produced by bacteria to inhibit the growth of similar or closely related bacterial strains. Many lactic acid bacteria produced a high diversity of different bacteriocins. In fermented foods, lactic acid bacteria display numerous antimicrobial activities. This is mainly use to the production of organic acids mainly lactic acid, they cause rapid acidification of the raw materials through the production of organic acid. In addition, their production of acetic acid, ethanol, aroma compounds, bactericins, exoplolysaccharides and several enzymes is of great importance especially in fermented foods, resulting in a high degree of control over the fermentation process and standardization of the end point. For instance, lactice acid bacteria (LAB) are capable of inhibiting various microorganisms in a food environment and displays crucial antimicrobial properties with respect to food preservation and safety.

CHAPTER ONE

1.0   INTRODUCTION

Bacteriocins are antimicrobial proteins produced by bacteria that kill or inhibit the growth of other bacteria. The first bacteria was originally identified in 1925 as an antimicrobial protein produced by Escherichia coli and was named cohian in accordance of the producing species on which it was identified. Today it is known that bacteriocins comprise a large and functionally diverse family. They are all ribosomally synthesized proteinaceous compounds and are active against bacteria closely related to the producing bacteria. Many lactic acid bacteria (LAB) produce a high diversity of different bacteriocins. LAB have a long   history of application in fermented foods because of their beneficial characteristics. They cause rapid acidification of the raw materials through the production of organic acids mainly lactic acid. In addition, their production acetic acid, ethanol, aroma compounds, bacterionocins’ exopolysacharides, and several enzymes is of important.  Whereas a food fermentation is nowadays performed by eh deliberate addition of LAB as starter culture to food matrix. This has been a breakthrough in the processing of fermented foods, resulting in a high degree of control over the fermentation process and standardization on the end product. Recently, the use of functional starter alters a novel generation of starter cultures explored. For instance, LAB are capable of inhibiting various microorganisms in a food environment and display crucial antimicrobial properties with respect to food preservation and safety (

In addition, it has been shown that some of LAB process   interesting health. Probiotics is the potential to combat gastrointestinal pathogenic bacteria such Helicobacter pylori, Eucherichia coli and salmonella.

1.1   Bacteriocin Production in Foods: Application Possibilities

Bacteriocins can be used as food additives. For instance, nisin is   commercially made in a partially purified form and a marketed preparation with the pediocin pA. (ACH)  producer is available. As an alternative to the addition of bacteriocins to foods, bacteriocins may be produced directly in the food as a result of starter culture or co-culture activity. Several studies have indeed indicated that lactic acid bacteria (LAB) starter culture or co-culture are able to produce their bacteriocins in food materials as consequently display inhibitory activity towards sensitive food spoilage or pathogenic bacteria the latter trait has mainly been documented for fermented sausage and sourdough. Because of the complexity of the food matrix and the difficulty of quantifying bacteriocin activities in foods, in vitro.