La revue Viandes et produits carnés

La revue française de la recherche en viandes et produits carnés  ISSN  2555-8560




Stabilization of bacterial contaminants in cooked hams after high-pressure treatment and addition of a protective culture

Bacterial communities present on diced cooked ham were characterized. They were dominated either by Firmicutes or by proteobacteria, with some species that have not yet been cultivated. Their dynamics after high-pressure treatment and addition of a protective culture was monitored. Although each bacterial community reacts differently to the treatments, the combination of high pressure and biopreservation indeed stabilizes the product with overgrowth of the protective culture.

Presentation of the project BLacHP (2015-2019)

Refrigerated meat products are perishables with a reduced storage life. In addition, vacuum-packed storage or with a modified atmosphere at refrigerated temperatures may provide a selective advantage to the development of psychotrophic sporulating bacteria from the Bacillus and Clostridium genera. Thus, preservatives, such as nitrites, are often necessary to ensure the safety of refrigerated products with low acidity during their storage life. Pressure by society to reduce chemical inputs in ready-to-eat food products is behind the BLac HP project whose aim is to develop a new strategy for the stabilization of refrigerated transformed meat products by combining high pressure (HP) and biopreservation with lactic bacteria. Using a multidisciplinary approach, our work has allowed the study of a combination of processes on several levels: cell, psychrophic spore species from Bacillus and Clostridium genera selected for a project and on the ecosystem scale. The dynamic response of microbial ecosystems to the processes was explored using molecular biology methods. At the same time, the effect of the processes on nutritional, technological and organoleptic properties of ham cubes was also evaluated. In addition, the environmental and societal impacts of the combination of the processes were evaluated in comparison with a conventional process for cooked ham. Finally, scaling up and transposition to other products have been considered.

Vacuum-packed meats: are the microbiological indicators reliable

Over the years, the bovine meat sector has seen atypical types of preservation means amongst vacuum-packed products (muscles and meat). Indeed, there has been an over-develoment of enterobacteria, an insufficient development of the bio-protective lactic flora, and even both problems without the meat and muscles showing any sensorial alterations. In order to understand this phenomenon and to help the sector avoid it, the French Livestock Institute in partnership with the Caen Normandy University, has led a study on the identification of microbial flora identified during the analysis of ready-to-cut muscle contamination and pieces of precut vacuum-packed meats after ageing under controlled conditions. The results obtained showed that in cases of atypical preservation, with reference methods, when the compliance threshold of the “enterobacteria” criteria is exceeded, it is the over-develoment of enterobacteria and notably the Hafnia alvei species that is responsible. However, the apparent under-development of lactic flora was caused by the exclusion of lactic bacteria of the genus Carnobacterium sp. and Lactococcus sp., causing an under-estimation of the real amounts of lactic flora present. This study has therefore provided evidence that a whole part of meats and muscles conditioned and preserved with vacuum-packed packaging is excluded from the marketing channels due to an error in the reference method that quantifies the lactic bacteria, therefore inducing an under-estimation of this compliance criterion for meat products. In order to remedy this problem, the French Breeding Institute and Interbev are working to develop alternative methods for the more precise evaluation of lactic bacteria present on the surface of meats.

Biochemical characterization of coproducts from slaughterhouses for their economic valorization

The valorization of coproducts is an economic question since most French slaughterhouses depend on the purchase price or the cost of removal that collection companies (foundries, rendering plants) apply without really having knowledge of the economic potential of valorized products. Animal by-products (ABP) which are not destined for human consumption, are used in several industrial branches (petfoods and oleochemistry mainly). They are transformed according to their category C1 or C2/C3 respectively as transformed animal proteins (TAP) or flour and as fats. The challenge is to allow slaughterhouses to valorize each ABP at an appropriate price, which will depend on the protein and fat contents and the capacity to extract them from flours/TAP and fats respectively. The INTERBEV interprofession ordered this study in order to initiate the construction of the first database for biochemical composition (proteins, lipids and dry matter) of 48 coproducts from large cattle, calves and sheep sampled in four French slaughterhouses. These data are the first available and will help build the first French reference table. Several studies today are exploring innovative ways of generating products with higher-value for the pharmaceutical, cosmetic and energy markets. The perspectives are to pursue acquiring data for the characterization of the added-value of each ABP or bioactive components whether they concern functional, nutritional or health properties.

Concentrate feeding and feed ingredients for growing-finishing.

Small improvements in feed efficiency, especially during indoor ‘winter’ feeding periods, can have a relatively large influence on farm profitability. Increasing the level of concentrates in the diet reduces forage intake and increases live weight and carcass weight gains, although at a decreasing rate. Subsequent compensatory growth at pasture diminishes the advantage of concentrate supplementation of young cattle. High digestibility grass silage with moderate concentrate supplementation can sustain a large proportion of the cattle performance achieved on high-concentrate diets. Feeding management is more important when feeding concentrates ad libitum than as a supplement. The relative nutritive (and economic) value of by-product feed ingredients depends on their inclusion level in the ration, and the amount of concentrates fed.

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