Protective cultures as natural antimicrobials for fresh meat shelf-life extension: their application and consumer acceptance
Creators: name: Xu, Michelle
Publisher: name: RMIT University
Year: 2024
Subjects: classificationCode: 300604
subject: Food packaging, preservation and processing

description: Protective cultures are microorganisms with the ability to inhibit undesirable microorganisms. They have the potential to be applied to food as natural antimicrobials to suppress the growth of pathogenic and spoilage microorganisms to improve food safety, quality, and shelf-life. While this approach has been promising for various meat products, research on the application of protective cultures for spoilage control and shelf-life extension of fresh red meat is scarce.

The primary aim of this Ph.D. project was to evaluate the effectiveness and practicality of using protective cultures to delay spoilage and extend the shelf-life of fresh red meat from both the technical application and consumer market acceptability perspectives. This work first tested six protective cultures in chill-stored lamb backstraps under three commonly used retail packaging systems to confirm the effectiveness of protective cultures against meat spoilage bacteria. Two promising protective culture and packaging combinations were also identified and applied to lamb backstraps and beef mince in subsequent more detailed storage studies to further evaluate their antimicrobial efficacy, effect on microbial community composition, impact on meat quality, and performance in different meat products. Lastly, this research conducted a national online survey of over 800 Australian consumers to understand consumer attitudes to packaged fresh meat products with protective cultures for shelf-life extension.

The main finding of this project was that protective cultures could effectively suppress the growth of spoilage bacteria without causing significant negative impacts on meat quality. However, their antimicrobial efficacy and impact on meat quality varied depending on the meat packaging system, culture species composition, and the meat product itself. When used with vacuum packaging, a single strain culture containing Lactobacillus sakei (now Latilactobacillus sakei) and a mixed culture containing Staphylococcus carnosus and L. sakei showed strong inhibitory effects against spoilage bacteria in both lamb backstraps and beef mince. However, as the inhibitory effects were only observed in lean beef mince but not in mince with higher fat content, the application of protective cultures may be limited to lean or low-fat fresh meat products. The two selected protective cultures dominated the microbial community of both lamb backstraps and beef mince analyzed using culture-dependent and culture-independent methods, respectively. These protective cultures did not affect the pH, texture, and microstructure of lamb backstraps but caused slight browning, whereas they lowered the pH of beef mince but had negligible impacts on mince color. For the first time, this project also revealed the potential market acceptability of using protective cultures for fresh meat shelf-life extension from consumer perspectives. With small proportions of consumers expressing unwillingness to purchase and consume packaged fresh meat products with protective cultures, consumer acceptance of these products would unlikely be an issue.

This research demonstrated that protective cultures could be used as a natural solution to extend the shelf-life of fresh red meat and help reduce food loss and waste. Protective cultures must be carefully selected and tested for application to a particular meat product to ensure antimicrobial efficacy and meat quality. This work provided information and insights about the practical application and consumer acceptance of fresh meat shelf-life extension using protective cultures, which could be used by the food and meat industries, manufacturers, and businesses to develop, adopt, and market this biopreservation technology.