Study On The Change And Safety Of Gibberellic Acid In Brewing Process

Gibberellins is a highly efficient broad-spectrum diterpenoid plant growth regulator,of which gibberellic acid（GA3）has the strongest physiological activity and is widely used in agricultural and agricultural products processing industry.Malt is the main raw material in beer brewing.The addition of GA3 to barley can promote the germination of barley and improve the quality of barley.However,is there any residues in the use of GA3?Is there a risk of food safety for subsequent beer products?There are no research conclusions yet.The paper first studied the changes of GA3 in the process of malting and wort preparation.The structure of the new substance（called Substance A）was analyzed by liquid chromatography-mass spectrometry（LC-MS）and nuclear magnetic resonance（NMR）.Then the conversion rate of GA3 into Substance A during beer brewing was studied.Acute toxicity and short-term toxicity of substance A were then assessed using an acute toxicity test and a28-day repeated dose toxicity test.The main findings of the paper are as follows:The content of GA3 in malting and wort preparation was first studied.The GA3 was added to the Australian barley SCO,Australian barley FAQ and Canadian barley,and the GA3was detected by high performance liquid chromatography（HPLC）.Studies have found that high temperatures promoted the degradation of GA3,and the longer time GA3 was exposed to high temperature,the more it degraded.When the wort is boiled,the GA3 content was zero.At the same time,it was found that the concentration of Substance A having different retention characteristics on the C18 column compared to GA3 was continuously increased.It was speculated that Substance A was produced due to the gradual degradation of GA3 during the process of roasting,mashing and boiling.Preliminary collection and structural analysis of substance A was carried out.Substance A was prepared using a semi-preparative HPLC technique,the mobile phase was 35%methanol and the flow rate was 3 mL×min^-1 in order to allow isocratic elution.The purity of Substance A was determined by LC-MS to be about 100%,and the mass spectrometry showed that the relative molecular mass of Substance A was 346 Da,which was the same as the relative molecular mass of GA3.Nuclear magnetic resonance（NMR）results showed that Substance A was an isomer of GA3.The concentration changes of Substance A in brewing process was analyzed.Gibberellic acid was added to the malt,and the addition amount was 1 g×kg^-1 of malt.The concentration changes of Substance A and the conversion rate of GA3 into Substance A in the stage of wort preparation,fermentation and the beer storage were measured.The results showed that during the mashing and boiling stages,the concentration of Substance A increased continuously,and the average conversion rates of GA3 were 30.4%and 87.0%,respectively,and the GA3 could not be detected in the wort.During the fermentation stage and beer storage process,the concentration of Substance A was stable.The average conversion of GA3 was up to 87.6%.Finally,the toxicity of Substance A was preliminarily studied.The results of acute toxicity study showed that Substance A was a low toxic compound with a half lethal dose(LD₅₀)of 2.82 g·kg^-1 BW,and its toxicity was higher than that of GA3.The 28-day repeated dose toxicity study showed that Substance A could cause weight loss in mice,and the CREA,TP,ALP,and ALB indexes of the drug-administered group were significantly different from those of the control group,and also caused inflammation and necrosis of the kidney and liver,but after the recovery period,the symptoms will be relieved.Due to the mild and reversible toxicity caused by continuous administration for 28 days in the low dose group,the application of GA3 in barley industry may be harmless to human body.