Effect Of Partial Substitution Of NaCl By KCl On Physicochemical Properties And Volatile Flavor Of Different Parts Of Dry Cured Ham

Dry cured ham is a kind of cured meat products consistingof the thigh of a hog,which is salted at low temperature and fermented at high temperature.Good quality ham with characteristics of golden skin,bright red color,white fat,strong flavor and favored by the vast number of consumers.However,traditional dry cured ham’s long processing time and high sodium salt content has been unable to meet the needs of modem market and consumers.Therefore,reducing sodium salt content and shortening processing time of dry-cured hamis thekey to its development.In this study,we further improved the technology of intensifying high-temperature ripening on the basis of previous stuieds,and partially replaced NaCl with KCl.The main purpose was to evaluate the effect of partial substitution of KClby KCl on physicochemical properties,lipid hydrolysis and oxidation and volatile flavor compounds of different parts of dry cured ham.We try to provide a theoretical basis for further development of low sodium ham.The research contents and results are as follows:1.Effect of partial substitution of NaCl by KCl on physicochemical properties of different parts of dry cured hamThe experiment was divided into salt group:100%NaCl,low sodium salt group 1:70%NaCl&30%KCland low sodium salt group 2:50%NaCl&50%KCI.The pig hind leg was used as raw material,pickled with 8%salt of fresh leg weight,cured for 45 days in a cold storage with a temperature of 2-4 ℃ and a relative humidity of 90%-95%,and then fermented for 150 days.Five processing points were sampled from raw materials(0 days),end of salting(45 days),end of low temperature fermentation(105 days),middle stage of high temperature fermentation(150 days),and end of high temperature fermentation(195 days).The ham was divided into four zones from the thickest part from the surface to the interior are zones A、B、C and D,respectively.The results showed that partial substitution of KCl to NaCl could increase the pH values to a certain extent,and there were no significant differences between different zones of ham,pH values from the surface to interior showed a downward trend.During processing time,moisture content and water activity decreased significantly,and the difference between surface and interior was significant.The replacement of NaCl by KCl had no significant effect on the moisture content and water activity of the ham.The content of sodium ions decreased significantly after partial substitution of KCI,and there was no significant change in the content of chloride ions.The penetration rate of potassium ion was greater than that of sodium ion.KCland NaCl had synergistic effect in salt infiltration.KClpartially replace NaCl,which can accelerate the penetration rate of chloride and sodium ions and shorten the time needed for balancing.PLS-DA analysis showed that different zones and processing time had a significant effect on physicochemical properties of samples,samples without adjacent sampling locations and processing time could be distinguished.2.Effect of partial substitution of NaCl by KCl on lipid hydrolytic oxidation of different parts of dry cured hamThe hydrolysis and oxidation of different parts of dry cured ham were studied under partial substitution of KCl for NaCl.The results showed that the activity of acid lipase,neutral lipase and phospholipase increased first and then decreased with the extension of processing time.At the end of fermentation,the activity of acid lipase and neutral lipase in the low sodium salt group was significantly higher than that in the salt group,but there was no significant difference in the activity of phospholipase,indicating that the substitution of KCl for NaCl had a certain effect on the activity of acid lipase and neutral lipase.TBARS value and lipoxygenase activityincreased first and then decreased with the processing time,they reached the maximum at the end of low temperature fermentation.At the end of the fermentation,the TBARS value of the low sodium salt group was higher than that of the salt group,the lipoxygenase activity was not significantly different.The results of correlation analysis showed that the hydrolytic oxidation and physicochemical properties of ham were significantly correlated,and the correlations were different under different salt treatments.3.Effect of partial substitution of NaCl by KCl on volatile flavor of different parts of dry cured hamThe composition of volatile flavor compounds of dry cured ham was detected by electronic nose and SPME-GC-MS.The results showed that partial substitution of KClfor NaCl significantly reduced salty taste of ham,but had no significant effect on color,hardness and aroma of ham.There were differences in color,hardness and salty but no significant difference in aroma of different parts of ham.The overall score of ham surface is higher than that of interior.The results of electronic nose analysis showed that there was significant difference between the salt group and the low sodium salt group,W1W,W2W and W5S sensors were their characteristic sensors.30 volatile flavor substances were detected in the salt group,mainly aldehydes and ketones,and 29 volatile flavor compounds were detected in the low sodium salt group,mainly aldehydes and acids.It indicates that KCl partially substituted for NaC has promoted the hydrolysis of fat and generated more carboxylic compounds.