Gibberellic acid (GA3) is an efficient plant growth regulator, which could speed up barley germination in the brewing industry. However, the residue of GA3 in malt gets denatured into an isomer, termed iso-GA3. In this study, the concentration of iso-GA3 and the conversion rate of GA3 to iso-GA3 during the brewing process was studied by high performance liquid chromatography and the potential toxicity of iso-GA3 was evaluated in ICR mice. The concentration of iso-GA3 increased in the saccharification and wort boiling processes while its concentration was stable during fermentation. The maximum conversion rates of GA3 to iso-GA3 in Canadian malt, Australian malt SCO and Australian malt FAQ were 88%, 87% and 87%, respectively. In the acute oral toxicity study, the median lethal dose (LD50) of iso-GA3 was 2.82 g/kg body weight (BW). In the 28-day repeated dose toxicity study, the iso-GA3 could cause weight loss in mice. And the mice of high-dose group showed a slight decrease in food consumption. Moreover, inflammation and cell necrosis were found in kidney and liver tissue, which were alleviated during the recovery phase. These results establish a practical reference for food safety in products, in which GA3 is added as a food additive.

中文翻译：

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赤霉素异构体（iso-GA3）在酿造过程中的残留分析及其对小鼠的毒性评估。

赤霉素（GA3）是一种有效的植物生长调节剂，可加速酿造行业中的大麦发芽。但是，麦芽中的GA3残留物会变性为异构体，称为iso-GA3。在这项研究中，通过高效液相色谱研究了酿造过程中iso-GA3的浓度和GA3向iso-GA3的转化率，并评估了ICR小鼠中iso-GA3的潜在毒性。糖化和麦芽汁煮沸过程中，iso-GA3的浓度增加，而在发酵过程中，其浓度稳定。在加拿大麦芽，澳大利亚麦芽SCO和澳大利亚麦芽常见问题解答中，GA3到iso-GA3的最大转化率分别为88％，87％和87％。在急性口服毒性研究中，iso-GA3的中位致死剂量（LD50）为2.82 g / kg体重（BW）。在为期28天的重复剂量毒性研究中，iso-GA3可能导致小鼠体重减轻。高剂量组小鼠的食物消耗略有减少。此外，在肾脏和肝脏组织中发现炎症和细胞坏死，在恢复阶段得到缓解。这些结果为添加食品中的GA3提供了食品安全的实用参考。