Method for Reducing the Content of Pathogenic Organisms Present in Food Materials

Abstract

The present invention relates to a method for reducing the concentration of pathogenic organisms such as Listeria spp. in fermented food products. The method comprises the steps of: (i) providing a food material, (ii) mixing said food material with a starter culture, (iii) mixing the food material with at least one adjunct culture in form of a bacteriocin-producing Pediococcus species, (iv) subjecting the mixture provided in step (iii) to a fermentation process, said fermentation process being conducted at conditions that are sub-optimal for growth of the bacteriocin-producing Pediococcus species in order to provide a limited acidification and allow for a high production of bacteriocin, and obtain a fermented food product. Furthermore, the invention relates to the use of bacteriocin-producing Pediococcus species as an adjunct culture for securing microbial safety of fermented food products.

1 . A method for the manufacturing of a fermented food product, said method comprises the steps of:
 (i) providing a food material,   (ii) mixing the food material with a starter culture,   (iii) mixing the food material with at least one adjunct culture in form of a bacteriocin-producing  Pediococcus  species,   (iv) subjecting the mixture obtained in step (iii) to a fermentation process, said fermentation process being conducted at conditions that are sub-optimal for growth of the bacteriocin-producing  Pediococcus  species in order to provide a limited acidification and allow for a high production of bacteriocin, and obtain the fermented food product.   
     
     
         2 . A method according to  claim 1 , wherein the fermented food product is subjected to a drying process simultaneously with the fermentation process in step (iv) and/or subsequent to the fermentation process in step (iv) to obtain a dry fermented food product. 
     
     
         3 . A method according  claim 2 , wherein the drying process is conducted at conditions that is sub-optimal for growth of the bacteriocin-producing  Pediococcus  species. 
     
     
         4 . The method according to  claim 3 , wherein the condition that is sub-optimal for growth is a temperature equal to or below 30° C., such as equal to or below 25° C., e.g. equal to or below 20° C., such as equal to or below 15° C. 
     
     
         5 . A method according to any one of the proceeding claims, wherein the bacteriocin-producing  Pediococcus  species is  Pediococcus acidilactici . 
     
     
         6 . The method according to any one of the proceeding claims, wherein the maximum difference in pH-value caused by the addition of the at least one adjunct culture is 0.5 pH-unit or less, such as 0.25 pH-unit or less, e.g. 0.1 pH-unit or less, such as 0.25 pH-unit or less, e.g. 0.075 pH-unit or less, such as 0.06 pH-unit or less, e.g. 0.05 pH-unit or less, such as 0.04 pH-unit or less, e.g. 0.03 pH-unit or less, such as 0.02 pH-unit or less, e.g. 0.01 pH-unit or less 
     
     
         7 . The method according to any one of the proceeding claims, wherein the sub-optimal growth conditions is provided by changing at least one of the parameters selected from the group consisting of temperature, nutrients such as the carbon source, additives and amounts of bacteria. 
     
     
         8 . The method according to  claim 7 , wherein the temperature in the fermentation process is equal to or below 30° C., such as equal to or below 28° C., e.g. equal to or below 26° C., such as equal to or below 24° C. 
     
     
         9 . The method according to any one of the proceeding claims, wherein the addition of the at least one adjunct culture increases the inoculation level of total lactic acid bacteria at least 1000 times, including at least 100 times, 50 times, 25 times such as at least 10 times, e.g. at least 4 times, such as at least 3 times, e.g. at least 2 times. 
     
     
         10 . The method according to any one of the proceeding claims, wherein at least one adjunct culture is added in a concentration in the range of 10 2 -10 10  CFU/g product, e.g. in the range of 10 2 -10 9  CFU/g product, such as in the range of 10 3 -10 9  CFU/g product, e.g. in the range of 10 4 -10 9  CFU/g product, such as in the range of 10 2 -10 8  CFU/g product, e.g. in the range of 10 2 -10 7  CFU/g product, such as in the range of 10 3 -10 7  CFU/g product, e.g. in the range of 10 4 -10 7  CFU/g product, such as in the range of 10 5 -10 7  CFU/g product, e.g. in the range of 10 6 -10 7  CFU/g product such as in the range of 10 3 -10 6  CFU/g product, e.g. in the range of 10 3 -10 5  CFU/g product, such as in the range of 10 2 -10 4  CFU/g product. 
     
     
         11 . The method according to  claim 10 , wherein the at least one adjunct culture is added in a concentration of 2×10 7  CFU/g product. 
     
     
         12 . The method according to any one of the proceeding claims, wherein the fermented food product is selected from the group consisting of fermented dairy products such as various cheese products, fermented meat products such as sausages e.g. spreadable and dried sausages, fermented fish products and fermented vegetables. 
     
     
         13 . A fermented food product obtainable by a method according to any one of  claims 1 - 12 . 
     
     
         14 . Use of a bacteriocin-producing  Pediococcus  species as an adjunct culture for securing microbial safety of a fermented food product, wherein said culture, when added to a food fermentation process, is being subjected to conditions that are sub-optimal for growth of said species, thereby producing bacteriocin without significantly affecting the acidification profile of the fermentation. 
     
     
         15 . The use according to  claim 14 , wherein the condition that is sub-optimal for growth is a temperature equal to or below 26° C. 
     
     
         16 . The use according to  claim 14 , wherein the adjunct culture is provided in a suitable package. 
     
     
         17 . The use according to  claim 16 , wherein said package, or corresponding marketing material, is provided with instructions indicating the fermentation conditions the adjunct cultures should be subjected to. 
     
     
         18 . Use according to  claim 17 , wherein said instructions, or corresponding marketing material, comprises indications that recommend a fermentation temperature equal to or below 26° C. 
     
     
         19 . Use according to any one of  claims 14 - 18 , wherein the adjunct culture is a freeze-dried preparation of B-LC-20 (DSM 10313) provided by Chr. Hansen A/S under the Trademark SafePro™. 
     
     
         20 . Use of  Pediococcus acidilactici  strain DSM 10313 as a bioprotective agent. 
     
     
         21 .  Pediococcus acidilactici  strain DSM 10313. 
     
     
         22 . A method for improving the suppression of growth of pathogens such as  Listeria  spp. in a fermented food product, said method comprises the steps of:
 (i) providing a food material,   (ii) mixing said food material with a starter culture,   (iii) mixing the food material with at least one adjunct culture in form of a bacteriocin-producing  Pediococcus  species,   (iv) subjecting the mixture provided in step (iii) to a fermentation process, said fermentation process being conducted at conditions that are sub-optimal for growth of the bacteriocin-producing  Pediococcus  species in order to provide a limited acidification and allow for a high production of bacteriocin, and obtain a fermented food product.