| Traditional dry cured meat products are favored by the majority of consumers due to its unique flavor and special taste. They have a stable market share and can not be replaced by other meat products. Chinese traditional dry-cured meat generally has very high salt content andthe salt content is in general several times higher than other food, which pose a great threat to human health. In addition, they have several shortcomings limit its production and market competitiveness such as the long production cycle, unhealthy, excessive additives, lack of convenient for eating, high cost, low commodity form. Therefore, the development of a low-sodium, ready to eat, delicious dry cured meat products processing methods to improve the traditional craft of dry cured meat products has important practical significance. This study researched the changes of lipolysis and lipid oxidation during processing. And we developed a low sodium dry-cured meat products, then we analysised the flavor components during the processing. The following is the contents and results of this paper:1) The change of lipolysis and oxidation of low-sodium dry-cured pork meat during processingTotal fat content of low sodium dry-cured meat slowly increased in line with the trend of salt group during processing, The neutral fat accounted for 74.78% which is the highest proportion of total fat. Then phospholipids followed by 21.6%. Free fatty acids share the smallest proportion accounted for 3.61%. The phospholipid degradation is large because about 40.23% phospholipid was hydrolysis. From the correlation analysis, as can be seen that free fatty acids were mainly from the hydrolysis of phospholipids. Relative contents of saturated fatty acids, monounsaturated fatty acids and polyunsaturated fatty acids of free fatty acids were gradually increased. Compared with the high value of relative content of polyunsaturated fatty acids, saturated and monounsaturated fatty acids are higher. The polyunsaturated fatty acids tended to decrease at postprocessing. And the linoleic and arachidonic acid were the main fatty acid which was oxidated and decomposited. These results showed that flavor components of low sodium dry-cured meat were mainly from the hydrolysis and oxidation of polyunsaturated fatty acids. The peroxide value and TBARs value begin to rise from the pickling stage quickly, indicating that the oxidation reaction started from salted stage. Both of them increased first and then decreased. The trend was similar with that of salt group.2) The change of lipolytic enzymes of dry cured pork meat during processing and the effects of different low sodium salt composition on enzyme activityNeutral lipase activity is the highestfollowed by acid lipase, phospholipase activity is minimum. Three enzyme activities decreased gradually, but the relative activity has remained. They palyed an important role in lipolysis. For the acid lipase, from the concentration range of 0-0.4M along with the increase of NaCl and KCl concentration relative activity decreased gradually. Along with the increase of Lys concentration, relative enzyme activity decreased at first and then increased. Along with the increase of His concentration, the relative activity increased gradually. The low sodium salt showed inhibitory activity across the concentration gradient and inhibition activity decreased with the increasing of concentration. For the neutral lipase, enzyme activity was inhibited by NaCl and KCl. Along with the increase of Lys concentration inhibitory of enzyme activity decreased. In 0.05M-0.2M concentration range enzyme activity was inhibited then was promoted by His. The higher concentration of low sodium the greater the inhibition of enzyme activity. For phospholipase, NaCl and KCl showed promotion for the enzyme activity firstly and then inhibition for the enzyme activity with the increase of concentration. But Lys showed inhibition for the enzyme activity firstly and then promotion for the enzyme activity with the increase of concentration. Along with the increase of His concentration, the role of promotiong for activity was greater. Low sodium in the low concentration range showed a slight role in promoting, then enzyme activity was inhibited with increase of concentrations.3) Research of technology of low sodium dry cured pork meat productsIn order to investigate the effect of process parameters on product quality, this study taked TBARs value,L* values and sensory scores for the response value to apply L9(34) orthogonal test processes. The optimal combination of technology as follows:temperature is 22 ℃;salt content is 3%;salted time is three days. Under the optimal technology this study researched the physical and chemical characteristics.The results showed that:the process point water content and Aw low sodium group are slightly higher than salt group, but no significant difference (P> 0.05). pH value of low sodium group was lower than the salt group, the sodium content of the final product was 1.687%,which is 48.04% lower than the salt group. The content of potassium content in the final product is 3.432% which is 59.45% more than salt groups. With the extension of the processing time,the L* values decreased;a* value increased and b* values decrease, Effect of color by low sodium salt and ordinary salt was not significantly (p> 0.05). Texture index such as hardness, chewiness and cohesiveness were increasing during processing, the value of hardness was slightly lower than salt group in the final product (p> 0.05). Sensory score of low sodium group products is 58 points just above the sensory score(57.8 points)of ordinary salt group, there was no significant difference.4) Research of volatile flavor compounds of low sodium dry cured pork meat products during processingUsing SPME-GC-MS separation to identify volatile flavor compounds,and a total of 61 kinds of compounds have been identified in low-sodium group and the control group during processing,including hydrocarbons, alcohols,aldehydes,ketones,acids,esters, phenols, furans,thiophenes,pyridines,terpenes,sulfurcompounds and chlorine compounds. Among thess compounds, aldehydes (hexanal, nonyl aldehyde, octyl aldehyde, etc.), alcohols (amyl alcohol, heptyl alcohol, phenethyl alcohol), ketones (2-butanone,3-hydroxy-2-butoxy ketone) and other compounds were the main volatile flavor components compentents oflow sodium dry-cured meat. |
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