Series: Brief measurement
What is instant soup stock?
“Soup stock” determines the taste of cuisine. As “soup stock” is used in many dishes, do you sometimes wonder what it is made of?
We examined Chinese soup stock using a mobile PCR device.
Suspension of 0.1 g of Chinese beef soup stock (made by company Y) and 0.9 mL of purified water.
The suspension was stirred using a vortex mixer for 30 seconds and left for 5 minutes (no centrifugation).
Then, it was diluted 10 fold (1), 100 fold (2), as well as 1000 fold (3), and
1 μL was taken from near the center and was used as a sample.
|μL||Remarks (final concentration)|
|Enzyme: KAPA 3G Plant (2.5 U/μL)||0.8||2U/reaction|
|Primer F: beef/pork/chicken (100 μM each)||0.06/0.06/0.1||400/400/600nM|
|Primer R: beef/pork/chicken (100 μM each)||0.13/0.14/0.1||800/900/600nM|
|Probe: beef/pork/chicken (100 μM each)||0.03 each||200nM each|
|PCR grade water||4.7|
Reaction sample total 16μL
Only the indicator for beef increased, indicating that beef is used as the ingredient. Measurement was possible even when the sample was diluted 10,000 fold.
Real-time PCR amplification curves observed in the measurement are shown in the figure below.
Measurement was performed using a multiplex of beef, pork and chicken.
*1 Primer/probe sequence
|Cow-Primer F 5′-CCCGATTCTTCGCTTTCCAT-3′ (20mer)||66.8|
|Cow-Primer R 5’-CTACGTCTGAGGAAATTCCTGTTG-3′ (24mer)||65.4|
|Cow-probe 5’FAM-CATCATAGCAATTGCCATAGTCCAC-BHQ1-3’ (25mer)||72.9|
|Pig-Primer F 5′-CTTGCAAATCCTAACAGGCCTG-3′ (22mer)||66.2|
|Pig-Primer R 5′-CGTTTGCATGTAGATAGCGAATAAC-3′ (25mer)||65.0|
|Pig-probe 5’ROX-AACAGCTTTCTCATCAGTTACACACAT-BHQ2-3′ (27mer)||70.2|
|Chicken-Primer F 5′-TCTGGGCTTAACTCTCATACTCACC-3′ (25mer)||65.6|
|Chicken-Primer R 5′-GGTTACTAGTGGGTTTGCTGGG-3′ (22mer)||65.6|
|Chicken-probe 5’Cy5-CATTCCTAACACTAGCCCTATTCTCC-3’BHQ3 (26mer)||70.3|
Made by Nihon Gene Research Laboratories Inc.
Tm values are calculated using the nearest neighbor method. However, the calculation method of Nihon Gene Research Laboratories was used for the probes.
Reference paper:Tanabe et al., A Real-Time Quantitative PCR Detection Method for Pork, Chicken, Beef, Mutton, Horseflesh in Foods.
Biosci. Biotechnol. Biochem., 2007, 71(12),3131-3135