Food Allergen ELISA

Q&A regarding Food Allergen ELISA Kit

Questions regarding performance

Q1. What can be detected by Food Allergen ELISA Kit?
A1. Food Allergen ELISA Kit can detect single proteins or partly-purified proteins derived from egg, milk, wheat, buckwheat, peanuts and soya. These are the proteins each kit can detect. Total protein mass of a specified ingredient is used as an indicator to detect the protein.
Q2. Which antibodies are used, monoclonal or polyclonal?
A2. Polyclonal antibodies are used for both solid-phased antibodies and enzyme-labeled antibodies.
Q3. What is the degree of light absorbance of a blank reagent and a 50ng/mL standard solution?
A3. As an indicator, light absorbance is less than 0.1 for a blank reagent, and 0.8-1.7 for 50ng/mL standard solution. Color development is affected by reaction temperature, etc.
Q4. How many samples can be tested by one kit?
A4. 96 well plate is used, so a maximum of 40 samples can be measured by dual measurement, and a maximum of 24 samples by triple measurement. When measuring a standard product, the number of samples is divided. The maximum number of samples will decrease with each use.
Q5. How should the Food Allergen ELISA Kits be stored? What is its expiration date?
A5. Please store the kit at 2-8°C. The expiration date is on the kit box, and on the test agent label. Furthermore, Reagent A for extraction can be stored at room temperature after dissolution.
Q6. Does the Food Allergen ELISA Kits contain any toxic agents, deleterious substances, or substances regulated under the PRTR Law?
A6. 2-mercaptoethanol, a non-medical deleterious substance, is used in each standard product. Please follow the use regulations.
Although it does not correspond to a toxic agent, deleterious substance, or substance regulated in PRTR Law, IN sulfuric acid is used in the reaction stop solution, please handle with care.
Q7. Why are there two types of the Food Allergen ELISA Kit for milk?
A7. One detects the main protein casein, and the other detects the main protein of whey fraction, β-lactoglobulin. For example, a β-lactoglobulin kit can be used for foods which contain milk serum proteins. By using a different kit in consideration of the manufacturing method and raw material of the targeted foods, a more substantial measurement result can be obtained.
Q8. Can you tell me about false-positive samples?
A8. Please refer to this for details regarding false-positive samples.
Q9. Can you tell me about false-negative samples?
A9. Responsiveness between antigen-antibodies changes in protein hydrolysate, measurement results may be less than the actual content. Please refer to this for details.
Q10. Can you tell me about the test method for a combination of foods such as an obento (boxed lunch) or instant noodles.
A10. Food such as an obento is considered as a complete package. And, bulk packaged food such as instant noodles are also considered as a complete package. Hence, everything is placed together in a food processor and homogenized to make form the sample.

Questions regarding the test agents and operation

Q11. Can the extraction solution from the Food Allergen ELISA Kit also be used for different items in the same kit?
A11. Yes, the same extraction solution can be used for all items.
Q12. Does 2-mercaptoethanol come with Food Allergen ELISA Kit? Do I need to prepare anything beforehand?
A12. When using Food Allergen ELISA Kit, please prepare 2-mercaptoethanol separately. Be sure to prepare 2-mercaptoethanol since it is effective in extracting proteins in the food.( Beta-Lactogloblin ELISA KitⅡ, Buckwheat ELISA KitⅡ and Soya ELISA KitⅡ are no need for 2-mercaptoethanol.)
Q13. Are There any common reagents in the Food Allergen ELISA Kits?
A13. The reaction stop solution, sample diluent, washing solution, and Reagent A for extraction can be used in common.
Q14. Can the washing solution prepared and stored in advance?
A14. Yes, it is possible, but please use it within a week.
Q15. How do I avoid contamination and mixing during homogenization?
A15. Be sure to clean the food processor.
  • Thoroughly clean the food processor to prevent contamination. Cleaning will be improved by soaking the food processor in an alkali detergent (e.g. Scat 20-X (Daiichi Kogyo Seiyaku Co., Ltd.)), using an ultrasonic bath, and adding alkali detergent to the cup and turning on the food processor.
  • Wear a different set of gloves with each food, and for each operation.
  • Weigh the powder sample and the sample containing the specified ingredient at the very end.
  • Place the scale in a separate room from the extraction and measurement room.
Since powder samples can be easily dispersed or mixed with other samples or solutions, handle them with care.
Q16. Can the extraction time be shortened?
A16. For protein extraction, denaturing, and reduction to be completely carried out, an incubation time of 10 minutes (short-time extraction) in boiling water, or shake-extract for 12 hours or longer at room temperature is required.
Q17. Can you give me some pointers regarding extraction?
A17. Finely homogenize the food so that it can be thoroughly extracted.
Place the sample in an agitator after mixing in a vortex mixer to thoroughly dissolve the homogenized food.
Pay close attention to the temperature because the protein may not be thoroughly extracted at a lower temperature.
Q18. When the sample is highly concentrated, what should I do?
A18. Dilute the sample using a supernatant or Diluent I to 20-fold, and then dilute with Diluent II as needed.
Q19. Why is light shielding needed during enzymatic reaction?
A19. When exposed to light, the background becomes higher. For good enzymatic reaction results, please shield the sample.
Q20. Do I have to measure absorbance immediately after reaction has been stopped?
A20. Please carry out measurement within 30 minutes after reaction has been stopped.
Q21. Do complementary wavelengths (dual wavelengths) need to be measured?
A21. Measurement can be carried out using only the main wavelength. However, since physical elements such as plate deformation can be removed by measuring the complementary wavelength, measurement in dual wavelength is recommended.
Q22. Can you give some pointers regarding washing operation?
A22. When washing by hand, be careful to avoid mixing the washing solution with the neighboring well. Remove any washing solution in the well by inverting and tapping the plate on a paper towel, etc. Next, wipe the bottom of the plate with a paper towel after completing the washing operation. When preparing many samples, a manual ELISA washing dispenser is convenient.
If a plate washer is used, rinse with washing detergent before and after use. Also be sure that the washing solution is uniformly dispensed from the nozzle, before using. After completing the last washing operation, remove any washing solution by inverting and tapping the plate on a paper towel, etc., the same as washing by hand.

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