Stomacher bagmixer 400

To evaluate changes in beef loin quality during storage, the pH, microbiological, and sensory characteristics were investigated. Hanwoo (grade 1) beef loins (Longissimus dorsi muscles) were purchased from the local meat packing center 24 h postmortem and sliced to 1.5 cm thickness. Each sample was wrapped with low-density polyethylene film and stored at 4 ± 2°C for 15 d. The oxygen transmission rate of low-density polyethylene film was 35,273 cc/m² /24 h at 1 atmosphere, 0.01 mm of thickness.
The pH was measured using a pH meter (Orion 230A, Thermo Fisher Scientific, Inc., USA) after 10 g of beef sample was homogenized with 90 mL of distilled water for 30 s.
For microbiological analysis, beef loin (10 g) was homogenized with sterile water (90 mL) using a BagMixer 400 Stomacher (Interscience, France) for 2 min, and 1 mL of diluent was plated onto APC Petrifilm (3M Microbiology, USA), which was incubated aerobically at 37°C for 48 h.
A 15-member sensory panel conducted the sensory evaluation of raw beef. The panelists were asked to score the raw beef for color, aroma, drip loss, and overall acceptability. The color, aroma, and overall acceptability were scored using a 9-point scale system from extremely like (9 points) to extremely dislike (1 point). Drip loss was the amount of water extracted from the meat; it was expressed from very high (9 point) to very low (1 point).

After irradiation, each sample (5 g) was cut into small pieces (approximately 0.5 cm × 0.5 cm) and homogenized for 2 min in a sterile Stomacher bag containing 45 mL of sterile saline solution using the Stomacher BagMixer® 400 (Interscience Co., France). Then samples were serially diluted in sterile saline (0.85%) solution, and each diluent (0.1 mL) was spread on each bacterial media. Tryptic soy agar (Difco Laboratories) was used for E. coli O157:H7 and L. monocytogenes. Plates were incubated at 37℃ for 48 h, and microbial counts were expressed as colony forming units per gram (CFU/g). Radiation sensitivity of the pathogens was calculated as D₁₀, a value that represents the dose required to inactivate 90% of the microbial population.

Each sample was cut into small pieces (approximately 0.5 × 0.5 cm) and homogenized for 2 min in a sterile Stomacher bag containing 45 mL of sterile saline solution using the Stomacher BagMixer^® 400 (Interscience Co., France). Then samples were serially diluted in sterile saline (0.85%) solution, and each diluents (0.1 mL) was spread on plate count agar (Difco Laboratories, USA). Plates were incubated at 37℃ for 48 h, and microbial counts were expressed as colony forming units per gram (CFU/g).

We used the method by Kim et al. (2016) (link) with slight modifications. Five grams of each sample was weighed and blended with sterile saline (45 mL, 0.85%, w/w) for 2 min using a laboratory blender (Stomacher BagMixer^® 400, Interscience Co., France). After blending, the samples were serially diluted with sterile saline, and each dilution (0.1 mL) was spread on plate count agar (PCA; Difco Laboratories, USA) plates. The PCA plates were incubated at 37°C for 48 h, and microbial counts were expressed as Log colony forming units (CFU)/g meat sample.

On days 1, 20, 45, 90, 135, and 180 of storage, 6 g of jerky sample was aseptically placed into a sterile stomacher bag with 225 mL of 0.1% peptone water and then homogenized for 3 min using the Stomacher Bag Mixer® 400 (Interscience, Osaka, Japan). These homogenates were serially diluted with sterile saline solution. For microbial analysis, 1 mL of the diluted sample was inoculated on 3M Petrifilm plates (3M Microbiology, Saint Paul, MN, USA) to determine aerobic plate counts, coliform/Escherichia coli count, and yeast and mold count. For total aerobic bacteria and coliform/E. coli, plates were incubated at 37°C for 48 h, and for yeast and mold, they were incubated at 25°C for 5 days in an incubation chamber (J070217, Jeio Tech, Korea). Each microbial count was recorded as Log colony-forming units per gram (Log CFU/g).