Jianxun Han

Simultaneous detection of eight food allergens using optical thin-film biosensor chips.

Food allergies are important food safety issues nowadays. To maintain the safety of people who experience allergic reactions, labeling is required in many countries and efficient and reliable detection methods are necessary. This paper reports a novel method for the rapid identification of food allergens through the use of a silicon-based optical thin-film biosensor chip with which color change results can be perceived by the naked eye without any extra equipment. The whole system can detect eight food allergens including soybean, wheat, peanut, cashew, shrimp, fish, beef, and chicken simultaneously. Sensitive and specific detection of the absolute detection limit of this method was 0.5 pg of cashew DNA, and the practical detection limit of 0.001%. The biosensor chip detection time was about 30 min after PCR amplification. The assay is proposed as a sensitive, specific, high-throughput, and ready-to-use analytical tool to detect the presence or confirm the absence of eight food allergens.

Species-specific identification of seven vegetable oils based on suspension bead array.

Species adulteration of vegetable oils has become a main form of adulteration in vegetable oils, severely violating consumer rights and causing disorder in the market. A reliable method of species authentication of vegetable oils is desirable. This paper reports a novel method for identification of seven species of vegetable oils based on suspension bead array. One pair of universal primers and seven species-specific probes were designed targeting rbcl gene of the chloroplast. Each probe was coupled to a unique color-coded microsphere. Biotinylated PCR amplicons of seven oils were hybridized to the complementary probes on microsphere sets. Bound amplicons were detected fluorometrically using a reporter dye, streptavidin-R-phycoeryt hrin (SA-PE). A sample could be analyzed less than 1 h after PCR amplification. With the exception of olive probe, all probes showed no cross-reactivity with other species. Absolute detection limit of the seven probes ranged from 0.01 ng/μL to 0.0001 ng/μL. Detection limit in DNA mixture was from 10% to 5%. Detection of vegetable oils validated the effectiveness of the method. The suspension bead array as a rapid, sensitive, and high-throughput technology has potential to identify more species of vegetable oils with increased species of probes.

A Real-Time PCR Method Targeting Camel Ingredient for Food Authentication.

The special nutritious value of camel showed high potential for market exploitation. In this paper, a real-time PCR method targeting camel ingredient in camel meat and milk is reported as an approach to fight against adulteration. To understand the impact of processing procedures on the amplifiability of cytb gene, four kinds of processed camel meat were investigated, and the rate of DNA breakage was explored. The method was able to detect 5 fg/μL camel DNA and highly processed food containing 0.01% camel meat with a high confidence level.

RAPD–2100 bio-analyzer and 2DGE methods applied to qualitatively and quantitatively assess grain purity of commercial malting barley

Grain purity is of great interest to malting barley trader and beer producer. DNA typing method has been applied for this purpose, but typically, single grain was tested and the procedure was expensive, laborious, and time-consuming. This study first reported fast semi-quantification of cereal seed by DNA test of blended sample. It was helpful for rapid screening of large amount of samples. Particularly, RAPD and 2100 bio-analyzer were combined to determine the purity range of malting barley grain taking advantage of mathematical linear relationship between concentration of marker bands and grain purity. Statistical analysis of 11 independent assays resulted in quantitative parameters for each RAPD marker band. Test of 14 samples using the fast method showed an average of 11% deviation to rated value. Protein profiling method helped to distinguish cultivars which were of identical RAPD pattern. Quantification by protein profile was also explored.