Analysis β-Glucan And Nitrogen Content Of Malt By Near Infrared Spectroscopy

The content ofβ-glucan and nitrogen in malt is one of the most important indexes for evaluating malt modification.But there were many disadvantages of usual chemical methods, it can not bu used for malt quality evalution in time and completely because of complex operation and long operation time.The content ofβ-glucan,total nitrogen and soluble nitrogen in malt can be determined quickly and accurately by Near Infrared Spectroscopy (NIR) after model improvement.It was compared the method for determining theβ-glucan content of malt with enzyme and fluorescence photometer.It was shown that the accuracy and repetition of enzyme method was better than latter.It was confirmed as the standard method for comparing the result of NIR.It was established that the mathematical model of NIR for quantificational determiningβ-glucan content of malt by partial least squares.The coefficient of predict and theory of crossing validation was 0.856,corresponding standard error of calibration was 0.05.The relationship of chemical determination and NIR predict was reached 0.827 with 60 malt samples.It was concluded that the maltβ-glucan content could be predicted accurately by NIR model.It could be used in the production for controlling the maltβ-glucan content.It was found that the malt total nitrogen content could be predicted accurately by NIR compared with chemical method.There was no relationship between the analysis result with NIR and chemical method for malt soluble nitrogen content.It was concluded that malt soluble nitrogen content could not be determined by NIP,accurately.In order to improve the accuracy and applicability of NIR model for malt soluble nitrogen content,some factors were investigated,such as standard samples representative, pre-treatment,samples temperature,color and sampling condition.It was found that predict result of NIR was influenced greatly by sample pre-treatment.The result was not affected by the sample color.The improved NIR model was then established after the wort was mashed with presentation malt samples.The bubble was avoided when the malt was put into the instrument. The sample's temperature was controlled between 21-25℃,R Square(RSQ) and 1minus the variance ratio(1-VR) of standard model was 0.983 and 0.9713,respectively,it was shown that the relationship was good.The malt soluble nitrogen content could be determined by NIR. It was concluded that the malt soluble nitrogen content could be determined accurately and quickly by NIR instead of traditional analysis method after model improvement.