Study On IMP Deposition Of Pork And Relativity With Freshness

IMP has been to taken as an important index to judge freshness of meat now .Research report about IMP in muscle mainly concentrated on physiology , pathology , immunology, neurology and so on currently in China.IMP also has been to taken as an important index to judge quality of meat ,but there were not systemic research about change of IMP concentration in muscle and dependability with quality of meat.There were less reports about flavor compound in pork during storage process .IMP as main umami compound in livestock, poultry and fish come from deposition of ATP, ADP , AMP , but it could not exist stably but degradate with enzyme . Hx and HxR are deposition of IMP , the degradation of IMP contribute to flavor loss and bitter increase of meat during storage process.This topic just reseach pork after abatage, to decide suitable chromatographic for analysising considerable sample, to investigate deposition rule of IMP and relativity with freshness.Study on the analytical method of IMP and its related nucleotide acidsWe investigated the HPLC analysis of IMP and its related nucleotide acids and the extraction method of the above nucleotide acids in pork in this experiment. The results were as follows: Using 0 .05M phosphate buffer (pH6.8) and methanol (gradient elution)as the mobile phase was the best condition, 0-12 minute: proportion of 0 .05M phosphate buffer descend to 97%, proportion of methanol raise to 3%, 0-22 minute: proportion of 0 .05M phosphate buffer descend to 90%, proportion of methanol raise to 10%.Running time in chromatogram of pork sample accord with standard sample, separated effect is good that there are few interferential peak. Concentration of nucleotide acids has favourable linear correlation with chromatographic peak area (R~2>0.998). Recovery rate of nucleotide acids all exceed 97%.Study on the deposition of IMP in pig muscleThe deposition of IMP in muscle of DLY, diplo-hybridism andYa-nan pig was studied in this experiment.The results were as follows: species, part of carcass, storage time influenced concentration of IMP significantly , concentration of IMP in muscle increased until sequentiluce after butcherring ,then decreased gradually ,changed rule were coincident whatever species and part of carcass , difference of concentration of IMP was significant during different storage time.when concentration of IMP in muscle reached top, concentration of IMP in longissimus dorsi, biceps femoris and psoas major of Ya-nan pig were significantly higher than corresponding part of DLY and diplo-hybridism Pig ( P<0.01) until storage end . Difference of concentration of IMP was significant among different parts of carcass during different storage period,but there was not significant rule。Concentration of IMP precursor in living body is important factor that influence concentration of IMP deeply , correlation analysis indicated that concentration of IMP precursor and concentration of IMP were inverse correlation(r=-0.59,n=18) before concentration of IMP reached top .Concentration of IMP precursor in living body could reflect metabolites of ATP (ATP+ADP+AMP+IMP+Hx+HxR) mediately. Concentration of IMP precursor in longissimus dorsi, biceps femoris and psoas major of Ya-nan pig were significantly higher than corresponding part of DLY and diplo-hybridism pig ( P<0.01) after butchered,so sum of metabolites of ATP in longissimus dorsi, biceps femoris and psoas major of Ya-nan pig were significantly higher than corresponding part of DLY and diplo-hybridism pig (P<0.01).Study on relativity between the deposition of IMP and freshness of porkK-value and T-VBN value increased during storage period ,and change rule were coincident ,it may be going to take K-value as new index for reflecting freshness of meat.K-value of psoas major of DLY ,diplo-hybridism pig and Ya-nan pig were significantly higher than longissimus dorsi and biceps femoris ( P<0.01), concentration of IMP metabolites was comparatively large that indicated metabolic process of psoasmajor was more quick than other parts.Study on the umami intensity of meat of different pig speciesSensory umami intensity of longissimus dorsi of DLY , diplo-hybridism pig andYa-nan pig were investigated in this experiment, aiming at inquiring the effect of IMP on pork umami intensity.The results were asfollowed : the umami intensity and the content of IMP were direct correlation (r=0.978,n=6) , flesh and soup were more delicious as soon as concentration of IMP increased .Concentration of IMP of longissimus muscle of back of DLY , diplo-hybridism pig and Ya-nan pig were significantly different during the same storage , but organoleptic investigation were not significantly different .Content of Hx and HxR increased during storge period ,but we did not feel bitter by organoleptic investigation,it indicate that Content of Hx and HxR did not influence flavor significantly.