Fermented Milk Production Using Lactose-Deficient Strains
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The slow growth of Lactobacillus casei in milk fermentation leads to prolonged fermentation times and increased risk of contamination, as existing methods using single strains result in slow acidification and inhibition of L. casei growth when combined with other lactic acid bacteria.
Innovation Solution
Fermenting milk with Lactobacillus casei and a lactose metabolism-deficient strain, such as Streptococcus thermophilus, which can metabolize sucrose, galactose, or glucose, to accelerate acidification and promote L. casei growth without inhibiting it, thereby reducing contamination risks and achieving higher cell counts in a shorter time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Lactobacillus casei is used as a single strain for fermentation, then the growth of L. casei is slow and fermentation time is prolonged (50-96 hours), but the risk of contamination is reduced due to limited bacterial activity window
Solution Approach 1:
The patent combines Lactobacillus casei with a lactose metabolism-deficient strain (such as Streptococcus thermophilus or Lactobacillus delbrueckii subsp. bulgaricus) to create a co-culture system. The lactose-deficient strain rapidly metabolizes alternative carbohydrates (sucrose, galactose, glucose) to produce acid quickly, accelerating the overall fermentation process and reducing the time window for contamination while maintaining high L. casei cell counts.
2Productivity
If Lactobacillus casei is combined with other lactic acid bacteria species (e.g., St. thermophilus) to increase acidification speed, then fermentation time is reduced to 15-20 hours, but the adjunct species grows faster and generates acid that inhibits L. casei growth, reducing L. casei concentration to only 3-5×10^7 CFU/ml
Solution Approach 1:
The patent employs a lactose metabolism-deficient strain that is specifically adapted to utilize alternative carbohydrates (sucrose, galactose, glucose) rather than competing for lactose with L. casei. This creates a functional division where the lactose-deficient strain handles rapid acidification through alternative sugars, while L. casei maintains its primary role in lactose fermentation, preventing mutual inhibition and preserving high L. casei concentrations (>1×10^8 CFU/ml) even during accelerated fermentation.
3Reliability
If Lactobacillus casei grows slowly in milk, then specific measures are required to prevent contamination, but these measures increase process complexity and time requirements
Solution Approach 1:
The patent introduces a lactose metabolism-deficient strain that rapidly consumes alternative carbohydrates and produces acid in the early stages of fermentation. This preliminary rapid acidification creates a low-pH environment quickly, which naturally inhibits contaminant growth before L. casei completes its slower fermentation process. This preliminary action reduces the need for complex ongoing contamination control measures throughout the extended fermentation period.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method allows for a high concentration of L. casei to be achieved in a shorter period while minimizing contamination risks, maintaining the same maximum cell count as single-strain fermentation and reducing fermentation time from 50-96 hours to 30-50 hours.
Implementation Method 1
The further strain will metabolize these carbohydrates quickly and thus begin to acidify the milk quickly
Implementation Method 2
The further strain produces amino acids and peptides in the milk by proteolysis of casein and other milk proteins
Data Source
AI summary
The present invention relates to a method of producing a fermented milk product comprising adding lactic acid bacteria to milk, wherein the bacteria comprise Lactobacillus casei and at least one further strain of lactic acid bacteria of a species other than Lactobacillus casei, wherein the further strain has a deficiency in lactose metabolism but is capable of metabolizing one or several carbohydrates other than lactose present in the milk.