Research On Gibberellic Acid In Malt And Beer

Gibberellic acid (GA3) is a plant growth regulator, it can speed up the germination of barley and improve the quality of malt when it is used in malting process. But, being one of plant growth regulators,gibberellic acid is a toxic chemical farming drug. According to Sigma, gibberellic acid may cause respiratory and liver cancer,belonging to suspected cancer-causing agents in RTECS standard. So when unreasonable used, it will cause a certain degree of human health hazards. Japan provides the highest gibberellic acid residues in fruits and vegetables are 0.2mg/kg and 0.02mg/kg in grains. A method was developed for the determination of gibberellic acid in malt by ultra performance liquid chromatograph tandem mass spectrometry. Sample was extracted with acetonitrile/water (80/20) in optimal ratio, and cleaned-up with an Oasis MAX cartridge. The separation was performed on an ACQUITY UPLCTM BEH C18 column(2.1×100mm 1.7μm)and the mobile phase was methanol / water/formic acid. Under a gradient elution, the results show that the gibberellic acid detected by select ion monitor was got a good separation. The recoveries range from 70% to 78% in malt and 90% to 96% in beer. The LOD of the gibberellic acid is 0.6μg/L and the relative standard deviations (RSDs) is less than 5%. The method is suitable for the determination of trace gibberellic acid in complex materials as malt, which has a good significance for people's health and export of agricultural products.If it was added reasonable in amount and way, gibberellic acid will improve the quality of malts. But if gibberellic acid was unreasonable used, it will not only add wort boiling color and bring other negative effects, but also cause gibberellic acid residues increased. Results in this paper show that when it is added in the way and amount of current malting industry, gibberellic acid has a same effect on three barley malt quality of different regions. Gibberellic acid has a significant improvement in quality of the three malts, when it is used in a small range of amount. But, when it was exceeded those amounts it will not only has a significant improvement in the quality, but also cause gibberellic acid residues increased linearly. So, it has a good significance for malting technology and the reduce of gibberellic acid residues,when gibberellic acid is used reasonably.The study show that gibberellic acid residues which bring by malt don't exist in beer. We find that gibberellic acid is decomposed in mashing and wort boiling stage. A decomposition product which has different retention characteristics in C18 column with the gibberellic acid is found and it is stable in beer when it is sterilize and storied to shelf life. The substance also has a same molecular weight and similar MS/MS spectra to gibberellic acid, and we identified and speculate the structure of this substance.