Sixty experimental Jinhua hams were processed by a traditional method using green hams from local Liangtouwu cross-bredpigs. Samples of Biceps femoris were taken from five hams randomly at each of the key stages of production, i.e., green ham,end of salting, end of sun-drying, middle of loft-aging, end of loft-aging, post-aging-1 and post-aging-2. Analysis of flavor compoundsshowed 89 compounds at the green ham stage and at the end of salting, 90 at the end of sun-drying, 91 at the middle ofloft-aging, 96 at the end of loft-aging, 93 at the post-age-1 and 94 at the post-age-2. The flavor compounds could be clustered inthe following chemical families: alkanes and alkenes, aromatic hydrocarbons, alcohols, aldehydes, ketones, carboxylic acids, esters,oxygenous heterocycle compounds, nitrogenous compounds, sulphur compounds, chloride compounds, amides, and terpenes. Duringprocessing, the concentrations of aldehydes and carboxylic acids increased; while the concentrations of alcohols, ketones, alkanes,alkenes, aromatic and cyclic hydrocarbons decreased. Sulphur compounds and pyrazines were formed and increasedcontinuously during processing. In the final Jinhua ham, the contents of aldehydes, carboxylic acids, alcohols and ketones were45.07%, 18.39%, 13.93% and 9.00% of the total flavor substances, respectively. The first principal component was a group dominatedby five unbranched aldehydes; the second principal component was a group dominated by five branched and unbranched alcohols,two branched ketones, toluene, hexane and 4-nitrophthalamide. The two principal components explained 90.6% of the totalflavor variance in Jinhua ham.

Sixty experimental Jinhua hams were processed by traditional methods using green hams from local crossbred pigs of Lanxi,Zhejiang province, PR China. Biceps femoris was sampled from five hams randomly taken after each processing stage. Potentialactivities of cathepsin B and L were determined. The effects of temperature, salt content, pH value and nitrate content on the activitiesof cathepsin B and L were evaluated using response surface methodology (RSM) and the actual activities of cathepsin B and Lduring Jinhua ham processing were calculated. The results showed that potential activities of cathepsin B and L decreased graduallyfrom 11332.05 to 9955.50Ug 1 prior salting to 1055.32-1359.90Ug 1 at the end of post-aging, respectively. After processing,about 9.31% original potential activity of cathepsin B and 13.66% original potential activity of cathepsin L were left. Temperature,pH value and salt content showed significant effects on cathepsin B and L activities. By stepwise regression analysis, two quadraticregression equation models were built individually for estimating cathepsin B and L activities. The models predicted that the actualactivities of cathepsin B and L were less than 5% of their corresponding potential activities most of the time before half of loft-agingand about 15% and 20% during the rest processing periods. Nevertheless, cathepsin B and L retained actual activities throughoutprocessing, especially during loft-aging and post-aging periods.

Sixty experimental Jinhua hams were processed by a traditional method. The potential alanyl aminopeptidase (AAP) activity inbiceps femoris was determined. The effects of temperature, salt content, sodium nitrate content and pH on muscle AAP were evaluatedusing response surface methodology. Porcine muscle was found to possess very strong potential AAP activity that decreasedgradually during processing from 201, 635Ug-1 before salting to 6147Ug 1 after aging. Temperature, pH and salt content hadsignificant exponential effects on AAP activity (P<0.001). Both temperature and salt content interacted with pH in their effectson AAP activity (P<0.01). However, 0-50mg L-1 sodium nitrate had no detectable effect on AAP activity (P>0.05). The regressionmodel showed muscle AAP maintaining its activity all through Jinhua ham processing, indicating that muscle AAP may generatefree amino acids during the processing and storage of Jinhua ham. The concentrations of free amino acids increasedsignificantly (P<0.05) during Jinhua ham processing, except for arginine and cystine. The concentrations of most free amino acidswere 5-20 times higher in the final product than in hams before salting. Final concentrations exceeded thresholds for sensory detection,thus implicating an important role of free amino acids in the determination of Jinhua ham flavor.

This study was designed to explore the bacterial diversity and the main flora in chilled pork by polymerase chain reaction-denaturinggradient gel electrophoresis (PCR-DGGE). Longissimus muscle was removed from pork carcasses at 24h postmortem. The muscle wastray- and vacuum-packaged at 4 1C for 2, 4, 7 days to extract the bacteria total DNA, respectively. The results indicated that the bacterialdiversity of chilled pork decreased with storage time regardless of packaging method. Nine types of bacteria were identified, includingArthrobacter sp., Enterococcus sp., Staphylococcus sp., Moraxella sp., Pseudomonas sp., Lactobacillus sp., Aeromonas sp., Acinetobactersp., Brochothrix thermosphacta. For tray-packaged pork, Pseudomonas sp. and B. thermosphacta were the dominant micro-organisms.The differences in the species found were related with the presence of Lactobacillus sp. in vacuum-packaged meat. The results of thepresent study might be useful to study the changes of the contaminating bacteria and their characteristics in chilled pork.

In this study, the effects of low-voltage electrical stimulation (LVES) and rapid chilling (RC) treatments on the quality characteristicsof beef carcasses were evaluated, including the rate of pH and temperature decline, evaporative loss of carcasses, purge loss,cooking loss, and shear force values of m. longissimus steaks. Each carcass of 28 Chinese Yellow crossbred (Simmental Yanbian)bulls was subjected to one of the four treatments, i.e., electrical stimulation and conventional chilling (ES/NR), electrical stimulationand rapid chilling (ES/RC), no electrical stimulation and rapid chilling (NE/RC), or no electrical stimulation and conventional chilling(NE/NR). Carcass pH and temperature were measured at 1, 3, 5, 7, 9, 11, and 24h post-mortem. After that, a 2.5cm-thick m.longissimus steak was taken from the right side of each carcass and used for analyses of purge loss, cooking loss and Warner–Bratzlershear force (WBSF). The results showed that LVES accelerated the rate of carcass pH decline (P<0.05) and rapid chillingincreased the rate of carcass temperature decline (P<0.05). There was no significant difference found for the mean carcass evaporativelosses from all treatments (P>0.05). Mean purge losses form. longissimus steaks from rapidly chilled carcasses were lower(P<0.05) than those from conventionally chilled carcasses. Electrical stimulation had no impact on m. longissimus steak purgelosses (P>0.05). Rapid chilling significantly decreased (P<0.05) the cooking loss of m. longissimus steaks from electrically stimulatedcarcasses whilst it increased the cooking loss of m. longissimus steaks from carcasses without stimulation (P<0.05). LVESincreased (P<0.05) cooking loss of m. longissimus steaks from conventionally chilled carcasses, but had no effect under the procedureof pre-rigor rapid chilling (P>0.05). The lowest mean shear force value was found for the ES/NR-treated m. longissimussteaks, whilst the highest one for the NE/RC-treated carcasses (P<0.05). Regression analyses indicated that carcass pH at 1 hpost-mortem was the most useful predictor for beef shear force. Abattoirs processing Chinese Yellow bulls could optimize meatquality by using low-voltage stimulation together with pre-rigor rapid chilling.