Growth of Aerobic Psychrotrophs and Color Changes of Precooked Beef Slices as Affected by Packaging Procedure1

Abstract

Precooked beef slices from top round roasts were used in replicate trials to determine the effects of packaging treatment upon shelf-life characteristics (microbial growth and color attributes) during retail storage. Roasts were dry-roasted to an internal temperature of 60°C, cooled for 1 h, then sliced (3–4 mm). Slices were packaged in: (a) vacuum; (b) 15% CO2, 40% O2, 45% N2; (c) 15% CO2, 20% O2, 65% N2; or (d) 15% CO2, 10% O2, 75% N2 and held at 4°C for up to 18 d. Enumeration of microorganisms and determination of color attributes were done at 0, 3, 6, 9, 12, 15, and 18 d of storage. Psychrotrophic counts were higher (P<.05) on slices stored 9–18 d in atmospheres containing ambient (20%) oxygen level as compared to the other packaging treatments. Vacuum packaging exhibited a greater lag phase for psychrotrophs. Vacuum packaged slices maintained a superior cooked beef color for 18 d and had greater (P<.05) chroma readings, indicating a greater color intensity.