Formation Regularity And Safety Evaluation Of 5-hydroxymethylfurfural In Black Garlic

As a processed product of garlic,black garlic has higher nutritional value and has been more and more popular with consumers in recent years.However,a certain amount of5-hydroxymethylfurfural(5-HMF)was formed during the aging process due to the thermal degradation of carbohydrates and Maillard reaction.Studies showed that 5-HMF was both toxic and pharmacological,and its security was still controversial.Therefore,it is of great significance to study the formation rule and safety evaluation of 5-HMF in black garlic,which can provide an important basis for the edible safety of black garlic,and guide the production of safer and healthier black garlic,thus promoting the development of garlic processing industry.The formation rule of 5-HMF in black garlic during the aging process was investigated by measuring the contents of 5-HMF,reducing sugar,total acid and total free amino acids,and analyzing the correlations between 5-HMF and others,and exploring the effects of different factors such as fructose,amino acids,and p H on 5-HMF content.The effect of5-HMF on the edible safety of black garlic was investigated by 28 days' oral toxicity test on mice.The main research results are as follows:(1)During the aging process of black garlic,with the increase of time,the contents of5-HMF and total acid increased,while reducing sugar and total free amino acids increased first and then decreased.5-HMF was positively correlated with total acid and reducing sugar,and negatively correlated with total free amino acids.(2)5-HMF was formed when heating fructose alone.Mixed amino acids could reduce the content of 5-HMF in fructose solution,and the higher the concentration of mixed amino acids,the lower the content of 5-HMF,and the higher browning degree of the solution.When the solution of different amino acid and fructose was heated,it was found that acidic amino acids could promote the thermal degradation of fructose to 5-HMF,while basic amino acids could reduce the accumulation of 5-HMF in fructose solution.But when the p H of the mixed solution was adjusted to 6,the content of 5-HMF was reduced by all the amino acids except lysine.Adjusted the p H of mixed solution of different amino acid and 5-HMF to 6,cysteine,lysine and tryptophan could reduce the accumulation of 5-HMF by react directly with it.The content of 5-HMF in the solution of fructose and mixed amino acids decreased with the increase of p H.(3)Reducing the processing temperature or soaking garlic in 5% tea polyphenols solution for 24 h before processing both can reduce the content of 5-HMF in black garlic.(4)28 days' oral toxicity test showed that 2 g/kg bw dose of black garlic alone had no adverse effect on the health of mice,but a certain dose of 5-HMF could cause the increase of aspertate aminotransferase and mild degeneration of renal tubular epithelial cells in mice.The results showed the NOAEL(No observed adverse effect level)of 5-HMF on mice was 200mg/kg bw,which was 1176 times of the possible daily intake of human by black garlic.Therefore,although a certain dose of 5-HMF was slightly toxic to mice,the body intake of5-HMF by black garlic was much lower than the NOAEL,so it can be concluded that 5-HMF had no adverse effect on the edible safety of black garlic in the case of a normal consumption of it.