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Characterization of the Heat Stable Bacteriocins Produced by Lactic Acid Bacteria Isolated from Dairy Products and Vegetables

Venkateshwari, S. (2008) Characterization of the Heat Stable Bacteriocins Produced by Lactic Acid Bacteria Isolated from Dairy Products and Vegetables. [Student Project Report]

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Abstract

This Dissertation / Report is the outcome of investigation carried out by the creator(s) / author(s) at the department/division of Central Food Technological Research Institute (CFTRI), Mysore mentioned below in this page.

Item Type: Student Project Report
Additional Information: A study was conducted to investigate LAB with potent antimicrobial activity within the microbial ecosystem and finally to select interesting strains that have the role of biopreservation. LAB were first isolated from milk (Carr et al., 2002; Metchinikoff) and have since been found in such foods and fermented products as meat, milk products, vegetables, beverages and bakery products (Aukrust & Blom, 1992). Lactic acid bacteria (LAB) have been used for centuries in the preparation, processing and preservation of foods and beverages. LAB have long been employed in fermentation as a food preservation technique because of the ability of LAB to inhibit the growth of undesired bacteria, due to the production of antimicrobial substances such as organic acids, diacetyl compounds, hydrogen peroxide and bacteriocins. Furthermore, lactic acid and other metabolic products contribute to the organoleptic and textural profile of a food item. The industrial importance of the LAB is further evidenced by their generally regarded as safe (GRAS) status, due to their ubiquitous appearance in food and their contribution to the healthy microflora of human mucosal surfaces. Though many gram positive and gram negative bacteria were able to produce bacteriocins, the bacteriocin produced by the LAB is widely used because of its GRAS status. From various Dairy and vegetable products, the bacteriocinogenic LAB were isolated. Both the bacteriocinogenic LAB and the bacteriocin were subjected to microbial, biochemical and molecular characterization. They were tentatively identified as Pediococcus sp. They produced the bacteriocin, Pediocin which is a Class IIa,The bacteriocin was found to be inhibitory against certain food borne pathogens, especially Listeria monocytogenes, which is of particular importance to the food industry and also to other pathogens such as S. aureus, S. typhi, S. paratyphi, Yersinia sp, Aeromonas hydrophila. They are inhibitory towards both Gram negative and Gram positive organisms, so they are said to be broad spectrum bacteriocin. The bacteriocin is treated with heat at 100°C for 15 minutes, 100°C for 30 minutes and 121°C for 30 minutes, the results indicated that all the bacteriocins were stable even at autoclaving temperature. Hence, it can persist and exhibit its inhibitory action in the cooked foods. Therefore, it can be used as an effective preservative. Except the strain B17 all are Non-Haemolytic, so all the other strains are safe to consume. Due to antilisterial, broad spectrum, heat stable, non toxic nature of the organism or the antimicrobial peptide–bacteriocin, it can be applied as a potent microbicidal preservative.
Uncontrolled Keywords: Bacteriocin antibiotics food preservation LAB dairy products vegetables
Subjects: 600 Technology > 08 Food technology > 23 Vegetables
600 Technology > 08 Food technology > 27 Dairy products
500 Natural Sciences and Mathematics > 07 Life Sciences > 04 Microbiology
Divisions: Food Microbiology
Depositing User: Food Sci. & Technol. Information Services
Date Deposited: 30 Oct 2008 11:01
Last Modified: 28 Dec 2011 10:05
URI: http://ir.cftri.com/id/eprint/8774

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