Research On Dense Phase CO₂ Sterilization Technology For Low-temperature Sausage

Low-temperature sausage is one of low-temperature meat products which are nutrient and popular. But low-temperature sausages can not be thoroughly sterilized during processing, which will easily induce the microbial spoilage and shorten shelf life. So the effective sterilization technologies for extending the shelf-life of low-temperature sausages are significant and indispensable. Dense Phase Carbon Dioxid(eDPCD)technology is a novel non-thermal processing technique. The effect of DPCD on the inactivation of bacteria from low-temperature sausages and the quality of low-temperature sausages were studied. And the Linear, Weibull and Log-Logistic model were used to fit the survival curves, respectively. The sterilization technics of low-temperature sausages based DPCD is established, at the same time, the novel sterilization technics was compared with traditional technics. Low-temperature sausages were treated by DPCD. After achieving the treatment procedure, Low-temperature sausages which were packaged in vaccum were separately stored at different temperature. Moreover, the growth of total microbial population for low-temperature sausages was observed during storage. The detailed aspects are as follows.Bacteria from low-temperature sausages were effectively inactivated by DPCD. The inactivation rate of bacteria increased with increment of treatment pressure, treatment temperature and exposure time. The maximal drop of the total viable counts was 4.8 lg cfu/g at 75℃, 50MPa and 30min. The minimum D value was 4.4min at 50MPa and 75℃, the minimum ZP value was 60.3MPa at 75℃, and the minimum ZT value was 30.6℃at 50MPa.But the D value and Z value hadn't drop evidently when the treatment pressure and temperature of DPCD exceeded some specific numerical value. The non-linear model could fit to bacterial inactivation kinetics curve by DPCD better than Linear model. Especially, the Weibull model could fit to the bacterial inactivation kinetics curve best..The pH value, protein content and water-holding capacity of low-temperature sausages had not change markedly after achieving DPCD treatment procedure. Reversely, the fat content, acid value and TVB-N value dropped evidently. The fat content increased with increment of treatment pressure and treatment temperature of DPCD. The acid value and TVB-N all dropped markedly when keeping the high treatment pressure and temperature of DPCD.57 kinds of flavor compounds were detected in raw low-temperature sausage, 62 kinds of flavor compounds were detected in low-temperature sausage treated by heat and DPCD. The main volatile components were the aldehydes, hydrocarbons, esters and alcohols. Only the benzothiazole was detected in heterocyclic compounds containing sulfur and nitrogen, and its relative content was very low, this may be related to the treatment temperature of samples. DPCD has no significant effect on the main volatile aldehydes and alcohols of low-temperature sausages. When the pressure of DPCD increase from 15MPa to 25MPa, hydrocarbons in low-temperature sausage increased significantly, the exact cause is unclear. The procedure of firstly having DPCD treatment and then heating was better than that of separate thermal treatment. But it was inferior to DPCD cooperating with heat, During storage, the total number of bacteria in low-temperature sausage treated by DPCD was obviously lower than ones treated by heat. The shelf life of low-temperature sausages treated by heat was 35, 28 and 14d at 4, 20 and 37℃. And the shelf life of low-temperature sausages could reach about 49, 35 and 21d for ones which were stored at 4, 20 and 37℃.