Evaluation of the weight loss of raw beef cuts vacuumpackaged with two different techniques

In the present study, 25 cuts of shank form adult cattle coming from the same slaughtering batch, were withdrawn just after manual sectioning/deboning, and each divided into two pieces (Prox and Dist) of approximately the same weight, that were vacuum packaged by using two different packaging systems: vacuum chamber machine with a bag material and a thermoforming packaging machine with top and bottom webs named BAG and THF respectively. The packed cuts were stored at 2-3°C for 20 days. The drip loss was calculated at the end of the storage as the difference between drained weight and net. Internal muscle pH and pH of the exudate present in the package and microbiological analyses (by pooling the samples) were performed at T0 and at the end of the storage. The drip loss, was significantly lower with BAG packaging: this difference was evident after 20 days of storage (average ± STD BAG vs THF = 1.04±0.36% vs 1.71±0.42%; P<0.01). The values were, in general, low for both the packaging systems, never above 2%. Moreover, shrink bag packages are characterized by better overall pack appearance and less plastic weight per pack. Forming step reduce the thickness of thermoforming material lowering the mechanical resistance and the barrier to oxygen, on the contrary after shrinking bag materials are thickened. The pH of muscles was stable, although a slight increase was evidenced after 20 (average ± STD BAG vs THF= 5.73±0.05 vs 5.78±0.09; P<0.01), due to the ageing of meat. The pH of the exudate was equal at T20 (average ± STD BAG vs THF = 5.34±0.20 vs 5.33±0.17). The drip loss didn't influence the development of all the microflora; in particular LAB, that represented the main microbial population, showed a gradual increase from T0 (2.20±0.41 Log CFU/g) to T20 (average ± STD BAG vs THF= 4.76±0.29 Log CFU/g vs 4.75±0.0.15 Log CFU/g). Enterobacteriaceae showed an increase, if compared to the initial counts, due to the prolonged storage and the gradual growth of ephemeral microorganisms, without differences among the two series (Enterobacteriaceae: T0=<1.7 Log CFU/g to T20 average ± STD BAG vs THF = 2.83±0.77 Log CFU/g vs 3.09±0.0.70 Log CFU/g). In conclusion, the use of the BAG system demonstrated to have an effect in reducing the drip loss of beef cuts during the refrigerated storage, with only slight influence on the other characteristics of raw meat.