Effect Of Ultrasonic Assisted Chlorine Dioxide On Microorganism And Quality Characteristics Of Germinated Wheat

Moderate germination can significantly improve the processing and eating quality of whole wheat food,and significantly increase the content of trace nutrients in wheat.However,the temperature and humidity conditions during wheat germination are suitable for microbial reproduction,and there are food safety hazards.Measures must be taken to control the growth of microorganisms in germinated wheat.In this paper,ultrasonic assisted chlorine dioxide was used to control the microorganisms of germinated wheat and its effects on bud length,root length and germination rate were studied.Then,the effects of different germination time on the physical and chemical properties and nutrient content of whole wheat flour after sterilization treatment were investigated.Finally,the whole wheat flour germinated for 48 h by ultrasonic assisted chlorine dioxide treatment was added to low gluten flour to make biscuits,and its effects on the quality of mixed flour and biscuits were studied.The main results are as follows:(1)Chlorine dioxide and ultrasonic treatment can control the number of microorganisms on the surface of germinated wheat.The optimum process conditions of chlorine dioxide sterilization were as follows: chlorine dioxide concentration 90 mg/L,soaking time 27 min,solid-liquid ratio 1:4,and the sterilization rate was 99.67%.Under the optimum conditions,the germination of wheat was treated for 48 h after germination,and the microbial reproduction was accelerated during germination.The ultrasonic assisted chlorine dioxide treatment during germination could significantly reduce the number of microorganisms and inhibit the growth of buds and roots.(2)The germination of wheat after sterilization had a significant effect on the physical and chemical properties of wheat.The moisture content of wheat grains increased significantly after germination,and the ash content,total starch content,amylopectin content,gluten index and falling number of whole wheat flour decreased significantly.Protein,wet gluten,amylose content and amylose/amylopectin ratio increased significantly.The contents of damaged starch and reducing sugar decreased first and then increased.With the prolongation of germination time,the color L* value of whole wheat flour increased significantly,and the a* and b* values decreased significantly.D10,D50,D90 and volume average particle size decreased significantly,and the body specific surface area increased significantly.The peak viscosity of whole wheat flour increased first and then decreased,and the change trend of gelatinization temperature had no obvious regularity.The water absorption of dough decreased first and then increased,the formation time,stability time and farinograph quality index decreased significantly,and the weakening degree increased significantly.(3)After the germination of sterilized wheat,the nutrient content of whole wheat was significantly increased.With the extension of germination time,the content of GABA increased significantly.Compared with the control group,the contents of essential amino acids,non-essential amino acids and total amino acids increased by 109.41%,73.68% and85.43%,respectively.The contents of vitamin B1 and B6 decreased.Compared with the control group,the contents of vitamin C and nicotinic acid increased by 22.87% and 13.27%,respectively.The content of folic acid reached the peak of 95.24 μg/100 g at 48 h,which was71.05% higher than that of the control group.The contents of α-tocopherol,β-tocopherol and vitamin E increased first and then decreased,and reached the maximum after soaking for 6 h,which increased by 17.52%,9.67% and 14.31% respectively compared with the control group.The contents of magnesium,sodium,copper and phosphorus increased,and the maximum values were 165.29 mg/100 g,37.17 mg/kg,6.00 mg/kg and 383.97 mg/100 g,respectively.The contents of potassium,calcium,iron,zinc and manganese decreased to varying degrees.The contents of soluble dietary fiber and total dietary fiber were lower than those of the control group,and the content of insoluble dietary fiber increased first and then decreased and then increased.The content of free phenol,bound phenol and total phenol increased significantly,which increased by 67.84%,32.16% and 43.69% respectively compared with the control group.The iron reduction ability of free phenol,bound phenol and total phenol increased significantly.(4)The addition of germinated whole wheat flour had a significant effect on the quality of mixed flour and biscuits.With the increase of the proportion of whole wheat flour,the moisture content of biscuit mixed powder decreased significantly,and the ash,crude protein and wet gluten content increased significantly.The color L* decreased significantly,and a*and b* increased significantly.The diameter and thickness of biscuits increased significantly,and the extension coefficient decreased significantly.The color L* decreased significantly and a* increased significantly.Hardness and brittleness increase first and then decrease;the appearance of biscuits gradually changed from golden to brown,and the pores on the back gradually increased.The roughness of biscuits gradually increases and the taste deteriorates.In summary,chlorine dioxide and ultrasonic treatment can control the number of microorganisms on the surface of germinated wheat.The germination of wheat after sterilization had a significant effect on the physical and chemical properties and significantly increased the content of nutrients.The biscuit sensory evaluation was acceptable when the addition of whole wheat flour was not more than 30% after 48 h germination.