Study On The Quality Change Of Preserved Beef During Processing

Ningxia Jingyuan yellow beef has become a national agricultural product that is protected by geographical indication and is an important economic pillar for regional economic development because of its unique flavor and low cholesterol.The current products are mostly frozen and fresh,therefore,in order to promote the diversified and high-value development of the industry,and cater to the consumer market demand such as regional tourism,the development of beef snack foods with regional characteristics has become an significant trend in the improvement of the industry.In this paper,Ningxia Jingyuan yellow beef is used as raw material to study the quality change laws of water migration,aroma composition changes and protein denaturation at different stages in the processing of beef jerky,and provide theoretical basis and guidance for the optimization and improvement of processing quality of beef jerky.The research contents and results are as follows:(1)The processing technology of beef jerky was studied.Through single-factor and orthogonal design experiments to obtain the optimal process parameters of beef jerky.The addition amount of beef jerky supplements was determined to be 2%salt,6%sugar,0.4%phosphate,2.5%soybean protein,6%starch,0.2%carrageenan,and 0.03%red yeast rice,respectively.The optimal conditions for the drying and roasting process of beef jerky are as follows:the drying temperature is 70?,the drying time is 1 20 mins,the roasting temperature is 170?,and the roasting time is 6 mins.Under these technological conditions,beef jerky has better sensory organs and meets the national standard requirements of GB/T 3 1406-2015 "Meat Preserved"and GB 2726-2016 "National Food Safety Standard Cooked Meat Products".(2)Using low-field nuclear magnetic resonance technology to explore the moisture status,moisture content and moisture distribution of beef jerky at different hot air drying temperatures.The result showed that the drying effect of beef jerky mainly depended on its non-flowing water content.During the drying process,the non-flowing water changes after free water and bound water,there is a good linear relationship between the moisture content of beef jerky and the peak area.The linear regression equation for drying at 70? is y=323.34x-6092.77(R2=0.9750),the longitudinal relaxation time T1-weighted image shows that the hydrogen proton density distribution during the hot air drying process of beef jerky at 70? is relatively uniform,the drying quality is high,and the color better.This research provided technical support and theoretical guidance for high-efficiency and high-quality dehydration and drying of dried meat products.(3)Using solid-phase microextraction gas chromatography-mass spectrometry(GC-MS)to study the changes of volatile compounds in raw meat,mixed meat,semi-finished products,and finished products during the processing of beef jerky.The results showed that in the entire processing process,the using of electronic nose can distinguish the odor of samples at each processing stage.A total of 113 volatile components were detected by the GC-MS method,and 70 major volatile compounds were screened out with a positive and negative matching degree>800.Among them,raw meat contained 40 kinds of volatile aroma components,39 kinds of seasoned meat,38 kinds of semi-finished products,and 30 kinds of semi-finished products.The concentration of volatile substances in mixed meat and finished samples all increased.During the entire processing process,aldehydes and alcohols are the main volatile compounds in the processing of beef jerky.Using partial least squares discriminant analysis(PLS-DA),the formation of volatile compounds in raw meat,mixed meat,semi-finished products and finished meat can be accurately divided into 4 processing stages.This research provides a theoretical basis for the improvement and detection of volatile aroma quality of beef jerky.(4)Using Fourier transform infrared spectroscopy technology,automatic deconvolution and curve fitting and other calculation methods to analyze the changes in infrared spectrogram and protein during processing of raw meat,mixed meat,semi-finished and finished meat degree of secondary structure denaturation.The results showed that the peak height and peak area of the infrared spectra of the four samples may change during the processing,and the peak wave number were red-shifted or blue-shifted.The stability of the protein secondary structure could be affected by drying and roasting etc,which resulted the second level of proprotein changed.The content of ?-helix,?-turn,and ?-sheet basically showed a downward trend,and the content of random coil basically showed an upward trend.The surface hydrophobicity of myofibrillar protein showed a slight upward trend as the progress of processing,which resulted in the reduce of the stability of the protein,weaking the interaction between the protein and water,and proning to hydrophobic aggregation.It is not conducive to the formation of the gel network structure,and the tenderness and juiciness of the meat products may be affected,and its nutritional value could be reduced.Above all,this research provides a theoretical basis for beef intensive processing and high-value applications.