Print this page. Print this page.

What is instant soup stock?

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.

Sample

Suspension of 0.1 g of Chinese beef soup stock (made by company Y) and 0.9 mL of purified water.

Pretreatment

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.

Reaction composition
μL Remarks (final concentration)
Enzyme: KAPA 3G Plant (2.5 U/μL) 0.8 2U/reaction
Buffer (×2) 8 x1
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
MgCl2(25mM) 0.8 1.25mM
Sample 1
PCR grade water 4.7

Reaction sample total 16μL

Program
Process Temperature Time
Initial denaturation 95℃ 15sec
Annealing/extension 60℃ 30sec 50cycle
Denaturation 95℃ 4sec

 

Results

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
Tm
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