Effects of storage under a modified atmosphere on the microbiological and organoleptic qualities of ground beef prepared from pasteurized manufacturing beef

Abstract

Summary A 40‐kg lot of manufacturing beef, i.e. meat used for the production of ground beef products, was collected at a beef packing plant. The lot was divided into two batches. One batch was pasteurized by immersion in water at 85 °C for 60 s, the other batch was not pasteurized. Both batches were then ground. The ground meat was packed in overwrapped trays, which were master packaged under a modified atmosphere of 70% O2 : 30% CO2. The master packs were stored at 2 °C for up to 12 days. At the time of pack preparation and at 2‐day intervals, a master pack containing pasteurized and another pack containing unpasteurized meat, were opened and retail packs from each master pack were displayed at 4 °C for 3 days. Samples for microbiological analysis were obtained at the times of opening master packs and at the end of display. Displayed meat was assessed daily for colour, discoloration and retail appearance, and for odour intensity and acceptability at the end of display. After either a period of storage or a period of storage and display, the numbers of bacteria recovered from pasteurized meat were less than the numbers recovered from unpasteurized meat. The colour of pasteurized meat was perceived as being paler than that of unpasteurized meat, but discoloration was similar or less, and retail appearance was similar or better for pasteurized than unpasteurized meat at all times. The odours of displayed, pasteurized meat were generally somewhat less intense and more acceptable than those of unpasteurized meat. The findings indicate that pasteurization of manufacturing beef to improve the microbiological safety of ground beef provides a product of acceptable appearance and enhanced stability during storage under a modified atmosphere and subsequent display in air.

Assessment of microbiological changes in fresh uncooked İnegöl meatballs stored under two different modified atmosphere packaging conditions

“…This type of an effect had previously been reported on red meats previously (2, 9, 18) and on ground beef (8,17). The samples from the C group had relatively high increases in their specific counts of Pseudomonas spp.…”

“…was noticed. This type of suppression on the growth of pseudomonads was previously linked to the inhibitory effect of CO 2 levels at or above 20% used in MAP by several authors (6,8). The reduction and/or stalling of B. thermosphacta at constant numbers during MAP conditions in our study is concordant with the findings of Tremonte et al (19), and discordant with the results of Tsigarida et al (20), Skandamis and Nychas (17,18), who reported increases in the numbers of this bacterium in their studies.…”

“…However, in studies with ground meat (8,17) and meatballs (6,14), it is normal to expect relatively higher initial counts, since increase in surface area of the meat could ease access of the residing flora to nutrients and its rapid growth. Also, the initial microbial load of the ingredients (14), various preprocessing factors in hygiene applications, and specific processing steps, as two holdings at 4°C required during production of ready to serve İnegöl meatballs, namely: a first 24 h holding of the ground and salt/sodium bicarbonate added meat mixture, and a second 24 h holding of the formed meatball before retail service, may well affect the microbial loads.…”

“…Microbiological sampling and analyses: At each sampling day, a 500 g package from each group was taken and 25g of sample was aseptically weighed into a sterile stomacher bag (Seward, London, UK), suspended in 225 ml sterile 0.1% (w/v) peptone water (OXOID, CM0009), and was homogenized in stomacher (Laboratory Blender, Seward, London, UK) (21) for 2 min at normal speed at room temperature. Tenfold serial dilutions of this initial dilution was performed, plated as duplicate onto/into appropriate agar plates and incubated as follows: Total aerobic mesophilic bacteria (TAMB) on (6,8,17). After incubations, colony counts on plates were converted to log cfu/g.…”

Shelf-life extension on fillets of Atlantic Salmon (Salmo salar) using natural additives, superchilling and modified atmosphere packaging

“…Modified-atmosphere-packed foods have become more available to meet consumer demand for fresh, refrigerated foods with extended shelf lives, being used to increase the shelf-life of fresh meat, poultry and fish products, among others (Chouliara et al, 2008;Gill and Badoni, 2003;Rosnes et al, 2006). The principle of MAP is the replacement of packaged air with a different, fixed gas mixture.…”