Study On New Processing Techniques Of Chilled Pork

There are several problems in the conventional processing of chilled pork, suchas difficulties in fat trimming and high purge loss. Chilled pork available on themarket had a short period of validity and fresh-keeping, and had not so good sensoryquality. This article introduced the development of processing and investigation,analyzed main influencing factors on purge loss of chilled pork based on manufacture,studied on joint application of hot fat trimming (HFT), spraying of organic acids andelectrical stimulation (ES) to resolve difficulties of chilled fat trimming (CFT) andhigh purge loss. This study optimized the modified processing parameter. Thefollowing conclusions were educed:ⅠBoneless boston shoulder (BBS), boneless picnic shoulder (BPS), bonelessloin and leg had notably different pH decreasing rate and ultimate pH. Acceleratedchilling (AC) increased the postmortem temperature decreasing rate of carcass,decreased pH declining rate, thus significantly reduced purge loss of boneless loin andleg measured at the 3rd and 6th day postmortem (P＜0.01), but no visible differenceswere detected during the latter storage. Chilling procedure (accelerated chilling, forshort AC and conventional chilling, for short CC) had little effect on purge loss ofBBS and BPS. Excising at 48th hour postmortem significantly reduced purge loss ofboneless loin and leg measured at 6th day compared with excising at 24th hourpostmortem(P＜0.01). Sample meat sizes also had significant influence on purge loss(P＜0.05). There were no visible differences on purge loss between the package ofvacuum and tray covered with film (P＞0.05).ⅡHFT significantly increased the speed of temperature decreasing, andtherefore significantly reduced purge loss measured at 6th day postmortem (P＜0.05for boneless loin and P＜0.01 for leg). HFT did overcome the difficulties of chilled fattrimming, improved appearance quality and productive efficiency, and reduced productive cost. But HFT enhanced shear force at the same time (P＜0.05 for bonelessloin, but P＞0.05 for leg), resulted in worse initial contamination of micro-organisms,made initial bacteria total number increased, shortened the period of validity andflesh-keeping consequently. If HFT was adopted in chilled pork processing, necessarymeasures should be taken to improve tenderness, to reduce contamination, and to keepflesh colonⅢSpray of organic acid (s) after HFT and before packing did eliminateproblems resulted from HFT, such as worse initial contamination and short period ofvalidity. Ascorbic Acid contributed to maintaining fresh color, it did extend the periodof keeping fresh color. Making a comprehensive view, lactic acid combined withAscorbic Acid was preference before packing.ⅣElectrical stimulation postmortem did reduced shear force of boneless loinand leg measured at the 2nd day postmortem (P＜0.01). At the same time, ES didincreased purge loss to a certain extent, but with the combination of HFT and excisingat 48th hour postmortem, this increment wasn't too large.ⅤInteraction of first chilling temperature and time was the most importantinfluencing factor on the purge loss in the combined application of HFT, ES andspraying of organic acids. Taking purge loss, shear force, bacteria total number,TVB-N, color and odor into account, and giving attention to operation and cost,chilled at -10±2.5℃for 90 minutes in the first chilling stage and excised at 24th hourpostmortem was the top-priority preference.