Low-Fat and High-Quality Fermented Sausages

Abstract

The present study, considering for the first time microbiological concerns due to the use of lemon albedo as a fat replacer, aimed at the selection of an anti-Listeria strain to be used as protective culture in low-fat southern Italian fermented sausages. In fact, these kinds of products require appropriate bio-protective strategies to avoid risks due to Listeria monocytogenes. Sixty-seven Lactiplantibacillus plantarum strains isolated from diverse sources were screened for their antimicrobial activity and their interaction with starter strains (Latilactobacillus sakei 152 and Staphylococcus xylosus MVS9). Lactiplantibacillus plantarum Lpls100, highlighting both listericidal activity and the ability to promote Staphylococcus xylosus MVS9 growth, was used as a protective strain in low-fat fermented sausages prepared with lemon albedo as a fat replacer. The effect of the albedo and the protective strain on the fermentation process and the final quality was ascertained. Results highlighted that the use of the albedo did not affect the growth of starter strains and enhanced some quality features, such as fatty acid profiles and certain sensory attributes. However, the albedo also produced a slow decrease in water activity, compromising the microbial quality. The anti-Listeria strain, enhancing coagulase negative cocci growth and exerting antimicrobial activity, avoided the inconveniences caused by the use of the albedo. Moreover, the anti-Listeria effectiveness was assessed through a challenge test using a Listeria cocktail. The study revealed that Lactiplantibacillus plantarum Lpls100, regardless of the presence of the albedo, assures a prompt inhibition of Listeria spp. Therefore, its use could be an important contribution to the quality of low-fat fermented sausages.

Keywords: Lactiplantibacillus plantarum; anti-Listeria activity; antimicrobial activity; bio-preservation; fat replacement; lemon albedo.

Figure 1

Cluster analysis shown as a heat-map with boxplot annotation concerning the anti-Listeria activity (Anti-Listeria_score) produced by sixty-seven Lactiplantibacillus plantarum strains isolated from different sources (origin). The anti-Listeria activity was assayed against Listeria monocytogenes (Lm_ATCC_15313) and four strains of Listeria innocua (Li_ATCC_33090, Li03, Li12, Li13).

Figure 2

Barplots of the CNC_compatibility index expressed by sixty-seven strains of Lactiplantibacillus plantarum against Staphylococcus xylosus MVS9. The different colors indicate strains grouped on the basis of high, moderate, or low compatibility.

Figure 3

Scatterplot comparing the indexes CNC_compatibility and Anti_Listeria_score of sixty-seven strains of Lactiplantibacillus plantarum isolated from different sources. The grey box encloses the strains with the two highest indexes.

Figure 4

Line plots showing the behaviour of pH (A) and a_w (B) in samples from batch C, conventional fermented sausage prepared with starter culture and 14% minced pork fat addition; batch A, prepared with 4% lemon albedo in total replacement of pork fat and starter culture addition; batch CPc, prepared with starter culture and 14% minced pork addition plus anti-Listeria Lactiplantibacillus plantarum Lpls100; batch APc, prepared with 4% lemon albedo in total replacement of pork fat and starter culture addition plus anti-Listeria Lactiplantibacillus plantarum Lpls100. The data are reported as mean values with error bars.

Figure 5

Line plots showing the behaviours of the main microbial groups in samples from batch C, conventional fermented sausage prepared with starter culture and 14% minced pork fat additions; batch A, prepared with 4% lemon albedo in total replacement of pork fat and starter culture addition; batch CPc, prepared with starter culture and 14% minced pork addition plus anti-Listeria Lactiplantibacillus plantarum Lpls100; batch APc, prepared with 4% lemon albedo in total replacement of pork fat and starter culture addition plus anti-Listeria Lactiplantibacillus plantarum Lpls100. The data are reported as the mean value with error bars. The dashed lines represent the limit of detection of the microbial groups.

Figure 6

Stacked bar plot (A) showing the distribution of fatty acids (PUFA, MUFA, SFA) and bar plot (B) showing the ratio PUFA/SFA in samples from batch C, conventional fermented sausage prepared with starter culture and 14% minced pork fat additions; batch A, prepared with 4% lemon albedo in total replacement of pork fat and starter culture addition; batch CPc, prepared with starter culture and 14% minced pork addition plus anti-Listeria Lactiplantibacillus plantarum Lpls100; batch APc, prepared with 4% lemon albedo in total replacement of pork fat and starter culture addition plus anti-Listeria Lactiplantibacillus plantarum Lpls100. The dashed line represents the threshold value 0.45.

Figure 7

Jitter plot showing nine sensory attributes at the end of ripening time (42 days) in samples from batch C, conventional fermented sausage prepared with starter culture and 14% minced pork fat additions; batch A, prepared with 4% lemon albedo in total replacement of pork fat and starter culture addition; batch CPc, prepared with starter culture and 14% minced pork addition plus anti-Listeria Lactiplantibacillus plantarum Lpls100; batch APc, prepared with 4% lemon albedo in total replacement of pork fat and starter culture addition plus anti-Listeria Lactiplantibacillus plantarum Lpls100. Black dots represent the mean value of 50 records. Statistical significance: **** p < 0.0001; *** p < 0.001; ** p < 0.01; * p < 0.05.

Figure 8

Scatterplot showing the challenge test of Listeria spp. during the ripening of fermented sausage from batch CL, fermented sausage prepared with starter culture and 14% minced pork Figure 4. strains of L. innocua (3 Log CFU/g); batch AL, prepared with 4% lemon albedo in total replacement of pork fat and starter culture addition 4 strains of L. innocua (3 Log CFU/g); batch CPcL, prepared with starter culture and 14% minced pork addition plus anti-Listeria Lactiplantibacillus plantarum Lpls100 and 4 strains of L. innocua (3 Log CFU/g); batch APcL, prepared with 4% lemon albedo in total replacement of pork fat and starter culture addition plus anti-Listeria Lactiplantibacillus plantarum Lpls100 and 4 strains of L. innocua (3 Log CFU/g).