This study investigated the effect of the addition of various levels of pig head meat (HM) as a substitute for rear leg meat (RLM) on the physico-chemical quality characteristics of non-emulsified, smoked, and cooked sausage during refrigerated storage. Sausages were prepared in four variations according to the proportion (0%, 10%, 20%, or 30%) of HM added and maintained at 4°C. Quality measurements were taken for 28 days. The sausages added with the addition of 20% and 30% HM had significantly (p<0.05) higher moisture and lower protein content compared to those without the addition of HM. The pH value during the storage period was higher (p<0.05) in the sausages to which the HM had been added than in those without HM. The sausages with 30% HM showed the lowest (p<0.05) L* and b* values and the highest (p<0.05) a* value during the storage period. The 2-thiobarbituric acid reactive substances (TBARS) content, hardness, cohesiveness, springiness, gumminess, and chewiness of the sausages showed no significant variations with the addition of various levels of HM. These data suggest that RLM could be substituted with 30% HM because it does not negatively affect the quality of the non-emulsified sausage. However, a further study on sausages made with 100% HM instead of RLM may be needed to improve its utilization.

The present study aimed to develop growth prediction models of Listeria monocytogenes in processed meat products, such as mixed pressed hams, to perform accurate microbial risk assessments. Considering cold storage temperatures and the amount of time in the stages of consumption after opening, the growth of L. monocytogenes was determined as a function of temperature at 0, 5, 10, and 15 ℃, and time at 0, 1, 3, 6, 8, 10, 15, 20, 25, and 30 days. Based on the results of these measurements, a Baranyi model using the primary model was developed. The input parameters of the Baranyi equation in the variable temperature for polynomial regression as a secondary model were developed: SGR = 0.1715 + 0.0199T + 0.0012T2, LT = 5.5730 - 0.3215T + 0.0051T2 with R2 values 0.9972 and 0.9772, respectively. The RMSE (Root mean squared error), Bf (bias factor), and Af (accuracy factor) on the growth prediction model were determined to be 0.30, 0.72, and 1.50 in SGR (specific growth rate), and 0.10, 0.84, and 1.35 in LT (lag time), respectively. Therefore, the model developed in this study can be used to determine microorganism growth in the stages of consumption of mixed pressed hams and has potential in microbial risk assessments (MRAs).

This study was carried out to investigate the effects of addition of aged garlic extract (AGE) on the color and lipid oxidation of ground chicken during refrigerated storage. The leg meat from 6 weeks-broiler was chopped and added with 4% of distilled water (control) and AGE, respectively, and then stored at 4±0.2℃ for 8 days. The commercial garlic was aged for the relatively short time (40-90℃/300 hr →natural dryness/40 hr→20-30℃/30-50 hr). The pH value was not significantly different between control and AGE-added chicken. The TBARS level of chicken was remarkably inhibited by addition of AGE during storage. In CIE color values, AGE-added chicken showed lower L* and higher b*, C* and Ho values than those of control during storage. Therefore, the addition of AGE in ground chicken enhanced the lipid oxidative stability and change to dark color.

Physicochemical changes of refrigerated chicken legs treated with acetic acid and trisodium phosphate (TSP) during storage at the temperature of 1±2℃ or 4℃. Chicken (average weight of 500±30 g) legs were treated with 2.5-10% (w/v) TSP and 0.5-2%(v-v) acetic acid soluions at exposure times of 10 min. pH values of chicken legs treated with 2.5-10% TSP significantly (P$lt;0.05) increased at initial days compared to control, which were consistent with the results of treatments of 5-10% TSP solutions for storage of 8 days at retail levels. Thiobarbituric acid (TBA) values of chicken legs treated with 2.5-10% TSP or 0.5-2% acetic acid solutions significantly increased from initial days to 4days of storage compared to controls. pH values of chicken legs treated with 0.5-2% acetic acid significantly decreased at initial days compared to control, which were consistent with the results of treatments of 1.5-2% acetic acid solutions for storage of 16 days at 4℃. Chicken legs treated with 0.5-2% acetic acid solutions were a significantly different Hunter color L^+ values during storage of 4 and 8 days compared to the controls. Chicken legs treated with 1-2% acetic acid solutions were a significantly different Hunter color a^+ values during storage of 16 days compared to the controls. Chicken legs treated with 0.5-2% acetic acid solutions were a significantly different Hunter color b^+ values during storage from 4 to 12 days compared to the controls.

The quality changes of hams and sausages in refrigerated storage were investigated. Seven types of hams and six types of sausages produced in Korea were collected from markets and stored at 10℃ according to the Food Code of Korea, and then chemical, microbiological, textural and sensory characteristics were evaluated at 30, 40 and 50 days. The proximal analysis showed considerable variation in fat with less variation in moisture and protein. The pH values of hams and sausages slightly changed with no consistent difference. Water activity values of all samples except one type of sausage were consistent over time in refrigerated storage. No purge losses of hams were observed except two types of samples in the intial stage. Several types of sausages showed purge losses with no consistency and one type of sausage showed consistent purge losses (0.44-11.29%) during the storage. The volatile basic nitrogen (VBN) content of hams and sausages was still within 20 mg% (Standard and Specification of Korea) on the 50th day, although the VBN of all samples significantly increased over time (p$lt;0.05). The thiobarbituric acid (TBA) values of hams and sausages were well below 1.0 during the storage, although the TBA values of all samples significantly increased (p$lt;0.05). However it was noticed that one type of ham and two types of sausages showed TBA values of 0.945, 0.928 and 0.978, respectively. All the standard plate counts (SPCs) of hams during the storage period showed a level below 30 CFU/g except one type of sample with 10³ CFU/g at 50 days. All the SPCs of sausages showed a level below 50 CFU/g except one type of sample with 10² CFU/g and two types of samples with 10⁴ CFU/g on the 50th day. Coliform groups were not counted in all samples during the storage. Instrumental texture analysis showed that springiness, cohesiveness, chewiness, gumminess and adhesiveness slightly changed with no consistent difference. The hardness of the hams showed a decreasing tendency, and the hardness of the sausages an increasing tendency with no significant difference. Sensory evaluation for color, flavor, taste, texture and overall acceptability showed decreasing tendencies over time (p$lt;0.05). The scores of the five sensory characteristics maintained the medium level of quality at the termination of the experiment. Although the results indicated that the ham and sausage samples were acceptable after the 50 days' storage at 10℃, the shelf-life of the samples should be determined considering the rapid growth of bacteria and the high TBA values at 50 days.

Quality changes of sausages in refrigerated storage for 60 days were investigated. Nine types of sausages produced in Korea were stored at 4℃(3-5℃), and then chemical, microbiological, and sensory characteristics were evaluated on every 10 days. The proximate analysis showed considerable variation in fat (23.97%, 17.10-30.20%) with less variation in moisture (51.96%, 48.10-66.30%) and protein (12.96%, 11.40-13.95%). pH value decreased over time averaging from 6.31 to 6.22 with no significant difference. Water activity was consistent over refrigerated storage averaging 0.95. Volatile basic nitrogen (VBN) values were still within 20 mg% though VBN for all types significantly increased over time (p$lt;0.05). Thiobarbituric acid (TBA) values were well below 1.0 though TBA showed significant differences among storage periods (p$lt;0.05). Standard plate counts (SPCs) significantly increased during storage (p$lt;0.05) while coliform group was not counted in all cases. SPCs reached 10^5 CFU/g in two types after 50 days' storage and were below 10^6 CFU/g in all types after 60 days' storage. Instrumental texture analysis showed that springiness, adheaiveneas, and hardness significantly decreased over the 60-day storage period (p$lt;0.05) while cohesiveness, chewiness and gumminesa did not change. Lightness, redness and yellowness of the internal Hunter color significantly decreased over time (p$lt;0.05) while no change was observed in external color. Sensory profile showed that flavor, taste, texture and overall acceptability significantly decreased over time (p$lt;0.05). The scores of the four sensory properties declined to the medium level of quality after 60 days' storage. The results suggested that the sausage samples were acceptable after 60 days' storage at 4℃. However, the shelf-life of the samples should be decided in the consideration of the growth rate of other spoilage flora coupled with the bacterial growth after 50 days' storage.