PCR method for the detection and identification of cultivars of rice flours used in yeast leavened breads containing both wheat and rice flours

Abstract

The identification of cereal grain sources in yeast leavened breads is challenging because of the mixtures of DNA from yeast and mixtures of related grains. DNA is decomposed during the fermentation and bread consists of not only rice but also wheat, yeast, sugar, butter, shortening etc. Wheat-specific and rice-specific PCR primers were developed to amplify the wheat DNA or rice DNA to detect the contamination of rice in wheat bread and to detect wheat contamination in rice bread. These primers are useful for PCR to prevent allergic patients from eating, unconsciously, bread contaminated with allergen cereals. A novel method was developed to identify or differentiate the cultivar of rice using a wheat/rice blended bread as a sample. The template DNA for PCR was prepared by the CTAB method followed by the extraction of DNA with 70% ethyl alcohol. Four kinds of suitable PCR primers were developed or selected to amplify only the DNAs of material rice without the proliferation of DNAs derived from wheat or yeast. It became possible to identify or differentiate these 4 kinds of characteristic rice cultivars from each other by PCR using the wheat/rice blended bread as a sample.