A novel PCR method for quantification of buckwheat by using a unique internal standard material.
A novel quantitative and specific method for detection of buckwheat, a known food allergen, in diverse food materials was developed by using a unique internal standard to compensate for the variability in DNA extraction and amplification efficiencies. The method was based on a real-time PCR targeting the internal transcribed spacer region of Fagopyrum spp. and was designed to detect both cultivated and wild buckwheat, because wild buckwheat might be potentially allergenic. As the internal standard material, ground seeds of statice (Limonium sinuatum) were added to food samples prior to DNA extraction, and the amount of statice DNA measured by real-time PCR was used to standardize the buckwheat content. Statice, an ornamental plant, was chosen as the internal standard material because it was readily available and was inferred to be least likely to be commingled in foods. The specificity of the PCR system was tested against commonly used food materials of plant origin. Quantitative results expressed in buckwheat protein concentrations (mean +/- standard deviation) for various food samples prepared to contain 10 ppm (wt/wt) of buckwheat flour (corresponding to 1.2-microg/g [ppm] buckwheat protein) ranged from 0.7 +/- 0.2 (rice) to 0.9 +/- 0.4 (wheat) and for 100-ppm (wt/wt) samples (12-microg/g [ppm] buckwheat protein) from 7.7 +/- 1.0 (pepper) to 9.8 +/- 0.5 (wheat) microg/g (ppm). The method's accuracy, sensitivity, and specificity were considered sufficient for detection of buckwheat contamination at the level required for compliance with the Japanese Food Allergen Labeling Regulation.
Hirao
Takashi
T
Somatech Center, House Foods Corporation, 1-4 Takanodai, Yotsukaido, Chiba 284-0033, Japan. t-hirao@housefoods.co.jp
Hiramoto
Masayuki
M
Imai
Shinsuke
S
Kato
Hisanori
H
D000485:Allergens / Q000302:isolation & purification*; D003257:Consumer Product Safety; D018744:DNA, Plant / Q000032:analysis; D019612:Fagopyrum / Q000235:genetics; D005504:Food Analysis / Q000379:methods; D005506:Food Contamination / Q000032:analysis*; D005512:Food Hypersensitivity / Q000517:prevention & control; D005515:Food Labeling; D010940:Plant Proteins / Q000032:analysis / Q000302:isolation & purification*; D016133:Polymerase Chain Reaction / Q000379:methods*; D015203:Reproducibility of Results; D012639:Seeds; D012680:Sensitivity and Specificity
D000485:Allergens; D018744:DNA, Plant; D010940:Plant Proteins