Control of Escherichia coli and Listeria monocytogenes in suckling-lamb meat evaluated using microbial challenge tests

Strategies for the Development of Bioprotective Cultures in Food Preservation

Consumers worldwide are increasingly demanding food with fewer ingredients, preferably without chemical additives. The trend called "Clean Label" has stimulated the development and commercialization of new types of bioprotective bacterial cultures. These bacteria are not considered new, and several cultures have been available on the market. Additionally, new bioprotective bacteria are being identified to service the clean label trend, extend the shelf life, and, mainly, improve the food safety of food. In this context, the lactic acid bacteria (LAB) have been extensively prospected as a bioprotective culture, as they have a long history in food production and their antimicrobial activity against spoilage and pathogenic microorganisms is well established. However, to make LAB cultures available in the market is not that easy, the strains should be characterized phenotypically and genotypically, and studies of safety and technological application are necessary to validate their bioprotection performance. Thus, this review presents information on the bioprotection mechanisms developed by LAB in foods and describes the main strategies used to identify and characterize bioprotective LAB with potential application in the food industry.

Spoilage of Chilled Fresh Meat Products during Storage: A Quantitative Analysis of Literature Data

A literature search was performed on spoilage of fresh meat products by combining keyword query, text mining and expert elicitation. From the 258 collected studies, a quantitative analysis was first performed to identify the methods which are the most used to evaluate spoilage beside the preservation strategies suggested. In a second step focusing on a subset of 24 publications providing quantitative data on spoilage occurrence time, associations between spoilage occurrence time of meat products and specific spoilage indicators were investigated. The analysis especially focused on factors well represented in the 24 publications, i.e., gas packaging (O2 and CO2) and storage temperature. Relationships between spoilage occurrence and several microbiological indicators were also sought. The results point out possible advantages of removing dioxygen in packaging to delay spoilage occurrence, whereas, in the presence of dioxygen, the carbon dioxide proportion in the gas mixtures was shown to influence spoilage occurrence. The collected data clearly reveal a potentially protective role of lactic acid bacteria. Besides, while a spoilage role could be attributed to Pseudomonas spp., the growth of mesophilic aerobic microbes, Brochothrix spp. and Enterobacteriaceae seemed independent of spoilage occurrence time.

Quality and storage stability of goat meat emulsion during refrigerated storage upon incorporation of α-chymotrypsin hydrolysed camel milk casein

Three different levels, viz. T1 (0.03%), T2 (0.06%) and T3 (0.09%) (w/w) of α-chymotrypsin hydrolysed camel milk casein was incorporated into goat meat emulsion, and compared with control (C: 0% hydrolysate) and positive control (PC: 0.02% butylated hydroxytoluene (BHT), w/w) for changes in quality at 4±1°C. During storage, the water activity, extract release volume and emulsion stability decreased significantly, while pH increased. Except in T3, improvement in antioxidant potential of treated emulsions was recorded. Lower fatty acid oxidation was recorded in treated emulsions during storage. The treated emulsions had better instrumental colour profile, however, lightness (L*), redness (a* value) and yellowness (b*) values decreased with the advancement of storage period. The microbiological counts in treated emulsions were initially reduced, and at the end of storage, significantly lower counts were recorded. In microbial challenging test (MCT), the colony forming units in treated emulsions decreased upto 4th day for all the tested pathogens, thereafter increased significantly on 6th day except in T3, whereas, in C and PC groups, the counts increased significantly throughout the storage period. The findings suggested that camel milk casein hydrolysate with α-chymotrypsin could be used as a potential food ingredient to improve its quality.

Lactic acid bacteria as protective cultures in fermented pork meat to prevent Clostridium spp. growth

In meat fermented foods, Clostridium spp. growth is kept under control by the addition of nitrite. The growing request of consumers for safer products has led to consider alternative bio-based approaches, the use of protective cultures being one of them. This work is aimed at checking the possibility of using two Lactobacillus spp. strains as protective cultures against Clostridium spp. in pork ground meat for fermented salami preparation. Both Lactobacillus strains displayed anti-clostridia activity in vitro using the spot agar test and after co-culturing them in liquid medium with each Clostridium strain. Only one of them, however, namely L. plantarum PCS20, was capable of effectively surviving in ground meat and of performing anti-microbial activity in carnis in a challenge test where meat was inoculated with the Clostridium strain. Therefore, this work pointed out that protective cultures can be a feasible approach for nitrite reduction in fermented meat products.