Microbiological characteristics of pork carcasses and vacuum packaged blade steaks during storage at 0±1°C

Date

2018-05-01

Journal Title

Journal ISSN

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Abstract

To evaluate the effect of extended post-harvest hanging time on pork sides and the microbial shelf-life of fabricated steaks, aerobic plate count (APC), Enterobacteriaceae (EB), yeast and mold populations, pH, and moisture content of pork sides hung for 21 days at 0±1°C was determined. After hanging, blade steaks fabricated from these sides were vacuum packaged, stored up to 35 days at 0±1°C, and evaluated for APC, EB, yeast and mold populations, and pH. Carcass cooler temperature and percent relative humidity, measured every hour during storage, averaged 0±1°C and 87.3% (66-100%), respectively. Pork carcass surface moisture content declined (P ≤ 0.05) from 65.1% on day 1 to 50.5% on day 21. The carcass pH was similar (P ≥ 0.05) at 5.88 on days 1, 7, and 14; however, by day 21 the pH declined (P ≤ 0.05) to 5.72. The flank, shoulder, and jowl were sampled on pork carcasses. There was no day effect for carcass APC; however, there was a location effect. The jowl had the highest (P ≤ 0.05) APC with 1.21 log CFU/cm². There was no carcass location or day effect for EB or mold populations, but there was a carcass location and day effect for yeast populations. The detection limit (DL) for EB and yeast and mold populations on pork carcass samples (n = 240) was 0.06 and 0.41 log CFU/cm² for the shoulder and flank, and jowl, respectively. For EB and mold populations, 98.8 and 97.9% of carcass samples, respectively, were below the DL. For yeast populations, 37.5, 45.0, and 63.8% were above the DL for flank, shoulder, and jowl, respectively. On days 1, 7, 14, and 21, 60.0, 55.0, 53.3 and 26.6% were above the DL, respectively, for carcass yeast populations; however, none were greater than 2.83 log CFU/cm². The pH of pork steaks was 5.69-5.89. There was a day effect for APC on pork steaks. The initial APC of steaks was 1.61 log CFU/g, increasing (P ≤ 0.05) to 5.06 log CFU/g on day 35. There was a day effect for EB and mold populations; but not for yeast populations. The DL for EB and yeast and mold populations on pork steaks (n = 102) was 0.70 log CFU/g. On days 0, 7, 14, 21, 28, and 35, the percent of EB populations above the DL on pork steaks were 0.0, 0.0, 23.5, 41.2, 94.1, 41.2%, respectively, however, none of the steak samples exceeded 4.40 log CFU/g. For mold populations, 100.0% of steaks were below the DL on days 0, 7, and 14. On days 21, 28, and 35, 18, 24, and 12%, respectively, were above the DL. None of the steak samples exceeded 2.68 log CFU/g for mold populations. For yeast populations, 56.8% of pork steaks samples were above the DL, but none were greater than 3.69 log CFU/g. These results indicate that pork carcasses and vacuum packaged shoulder blade steaks fabricated from these carcasses have acceptable quality for 21 and 35 days, respectively, when stored at 0±1°C after harvest.

Description

Keywords

blade steaks, microbial, pork carcass, storage

Graduation Month

May

Degree

Master of Science

Department

Food Science Institute

Major Professor

Elizabeth A. E. Boyle

Date

2018

Type

Thesis

Citation