Folate food & tissue

Folate Assay (Food or Tissue)


Per Sample

This 96-well format microbiological assay is considered to be one of the most effective methods for measuring folate levels in food or tissue.


Non-UNC Users
Please note that UNC requires that an additional percentage for overhead be charged to the base rate for external sales. Please contact us for pricing.


Service Description

This assay measures the growth response of the bacteria L. casei (ATCC 7469) to folic acid. Since these bacteria require folate to grow, the growth response is directly related to the folate level in the food or tissue sample. L. casei bacteria are used because they respond to the widest variety of folate derivatives. 5-formyltetrahydrofolate (5-formyl THF) is the major folic acid derivative found in food products and is therefore used as the standard in this assay. For determination of food folate, a tri-enzyme treatment is necessary to extract the folate in the sample prior to the assay. Protease and α-amylase are used to extract folate bound to protein or carbohydrate matrices. Rat serum conjugase is used to hydrolyzed polyglutamyl forms of folate to monoglutamyl forms which are measured in the microbiological assay. It has been reported that the tri-enzyme treatment consistently yields higher folate values when compared to the more traditional methods, which use either one enzyme or none at all. The coefficient of variation for this assay is 3.9%. The assay yields a linear response between 0 and 120pg.


Sample Processing

Food: Send 0.5 gram aliquots of food in 15 mL tubes and store at -80°C. Ship samples on plenty of dry ice for overnight delivery.

Tissue: Collect tissue by freeze-clamping in liquid nitrogen with pre-cooled freeze-clamping tongs. Pulverize frozen tissue under liquid nitrogen with mortar and pestle. Be sure to pre-cool the mortar and pestle and add liquid nitrogen to the mortar before adding tissue. Grind tissue to a fine powder (no chunks) in continuous presence of liquid nitrogen. Transfer powder to pre-cooled tubes. Next, weigh at least 100 mg pulverized tissue into 1.5 mL tubes and store at -80°C. Ship samples on plenty of dry ice for overnight delivery. Please note that pulverized tissue samples must be carefully weighed.


Important Notes

  • Send the amount of sample requested and be sure to specify weights and volumes!
  • Sample tubes must be numbered clearly and simply, e.g. 1, 2, 3,…100, and accompanied by a sample key (which also must be emailed) describing the sample, sample volume or weight, and position in sample box.
  • Ship samples overnight delivery with enough dry ice to last 72 hours in case the package is delayed. It happens all too frequently.
  • If shipping a cell pellet, do not forget to determine the cell number, cell protein, or cellular DNA for data normalization prior to shipping. We do not do not perform those analyses.


Standard Operating Procedures

Folate Assay (Food or Tissue)-Standard Operating Procedures


Shipping Information

Please contact us before you send your shipment. Send samples (in a styrofoam cooler on dry ice or ice packs overnight) with information to:
Steve Orena, Lab Manager
UNC Nutrition Research Institute
Metabolic Molecular Phenotyping Core-Kannapolis Facilities
500 Laureate Way, Room 2148
Kannapolis, NC 28081
T: (704) 250-5041


Have Questions? Contact Us.

Steve Orena, Lab Manager
Metabolic Molecular Phenotyping Core-Kannapolis Facilities
T: (704) 250-5041