Research On Rapid Determination Of Amino Acids In Fish Meal And Soybean Meal

With the development of intensive aquaculture and industrialization,the growth conditions of aquatic animals are completely controlled by human beings,and all the conditions required for their growth need to be provided by human beings,that is,the aquatic formula feed must provide all the amino acids it needs.In order to ensure the rational collocation of various amino acids in feed and timely adjustment of the formula,it is necessary to determine and analyze the amino acids accurately.At present,the national standard method for the determination of amino acids in feed requires that the protein in the feed be hydrolyzed in an oven at 110 ? for 20-24 h with an accurate volume of 6 mol / L hydrochloric acid(the volume can not be reduced).After cooling and mixing,a part of amino acid hydrolysate solution is quantitatively transferred and evaporated to dryness at a temperature not higher than 60 ?,and then determined by a special amino acid analyzer after accurate volume dissolving.The oxidation acid hydrolysis of sulfur-containing amino acids needs to be oxidized in ice water bath for 16-18 h before hydrolysis.Compared with other conventional nutritional indicators,the determination of amino acids in feed has the characteristics of longer cycle,more operation steps,higher energy consumption and slightly higher safety risk,which has become one of the bottleneck factors limiting its application.In order to solve the above problems,the microwave pretreatment system was used to improve the protein hydrolysis process in feed amino acid determination method to simplify the detection process,shorten the detection cycle,and evaluate the determination results.In addition,this study also tried to establish the NIR comprehensive scanning prediction model of water,egg,fat,fiber,ash and 17 kinds of amino acids of five kinds of aquatic feed raw materials and general fish feed,hoping to complete the determination of the above indexes in a short time by the rapid analysis method of near infrared scanning.The main results are as follows1.Application of microwave hydrolysis in determination of amino acids in fish meal and soybean mealIn the process of protein hydrolysis in the pretreatment of amino acid determination of fish meal and soybean meal,three hydrolysis methods of conventional acid hydrolysis,oxidation acid hydrolysis and alkali hydrolysis were studied and tried.By setting and optimizing the parameters of hydrolysis temperature and hydrolysis time,and taking pressure monitoring as auxiliary observation means,the optimal conditions of microwave-assisted protein hydrolysis were obtained as follows: after the sample was fully wetted,isolated from oxygen,heated to 160 ? for 20 minutes in a well sealed environment and kept for 20 minutes.The maximum pressure observed is usually around 5-8 bar.The result of this process is basically consistent with that of the traditional hydrolysis method for 20-24 H.This condition is also suitable for acid and alkali hydrolysis of amino acids.The oxidation conditions of 16-18 h ice water bath can be replaced by water bath at 55 ? for 30 min.2.Establishment and validation of near infrared analysis modelBased on the wet chemical analysis data,the prediction models of 17 kinds of amino acids in domestic fish meal by FOSS tr3750 near infrared spectrometer,domestic fish meal 2019(excluding tryptophan temporarily),and 17 amino acid prediction models of imported fish meal and soybean meal samples on bluker MPa near infrared spectrometer were established.For the samples with FOSS Mahalanobis distance less than 3 and Brooke Mahalanobis distance less than 1,the deviation between the scanning prediction results and the conventional amino acid determination results is less than 0.15,which meets the deviation requirements of GB/T 18868.The results showed that the microwave-assisted hydrolysis method could shorten the period of amino acid determination of aquatic feed by at least 24 hours compared with the national standard method,and simplify the pretreatment operation of amino acid determination.The evaluation results of the uncertainty in the measurement of amino acids in fish meal by microwave acid hydrolysis showed that the quality of the results was under control and the uncertainty met the requirements of the deviation of the results.The near infrared analysis can quickly give accurate prediction results of 17 amino acids for specific samples that meet the requirements of the model.The results show that microwave hydrolysis and near infrared analysis can greatly improve the efficiency of amino acid determination of aquatic feed,which is conducive to the popularization of amino acid determination of aquatic feed and its raw materials and the design of accurate formula.