Optimization of compositional and structural properties in probiotic sausage production

Effects of anaerobic and respiratory adaptation of Lacticaseibacillus casei N87 on fermented sausages production

Lacticaseibacillus casei N87 was used as starter culture for the production of fermented sausages. The strain was cultivated in anaerobic (A) and respiratory (growth in presence of oxygen and supplementation with haeme and menaquinone in the growth medium; R) conditions. Control without the starter culture inoculation and with the addition of 150 mg/kg of nitrate was also included. The effect on physico-chemical parameters (pH, Aw, weight loss, and color), microbial population, volatilome, proteolysis as well as the survival of the strain was evaluated during 90 days of ripening. Q-PCR and DGGE-PCR analyses demonstrated the ability of the strain used in this study to adapt to this environment and carry out the sausage's fermentation process. The inoculation of the strain did not have any effect on the Aw values, which decreased similarly in the different samples whereas the pH was lower in A samples (5.2) and the weight loss in R samples (2.5% less than the others). The color parameters of the samples inoculated with the starter cultures were comparable to those of the control added with nitrate. The concentration of aldehydes that usually are identified as marker of oxidation processes was similar in the samples inoculated with the starter cultures adapted under respiratory conditions and in the control. On the contrary, a higher level was detected in the samples inoculated with the starter cultivated under anaerobic conditions. The proteolysis that occurred during the ripening indicates the differentiation of the A samples from the others. Nonetheless, the volatile profiles of the inoculated fermented sausages were similar. The study demonstrated that aerobic adaptation of Lcb. casei N87 starter culture gave similar color parameters and amounts of aldehydes in sausages fermentations without nitrate compared to conventional fermentations with nitrate.

Detection of viable Lacticaseibacillus paracasei in fermented milk using propidium monoazide combined with quantitative loop-mediated isothermal amplification

To quantify viable probiotic Lacticaseibacillus paracasei (L. paracasei) in fermented milk accurately and quickly, propidium monoazide combined with quantitative loop-mediated isothermal amplification (PMA-qLAMP) was applied. The optimal PMA treatment conditions for treating a L. paracasei suspension were determined using an orthogonal test to eliminate the DNA amplification of 108 CFU/mL of dead L. paracasei. Primers were designed based on the species-specific gyrB gene of L. paracasei. A phylogenetic tree based on the gyrB gene showed that L. paracasei clustered on the same branch with 91% support. Compared with the 16 strains commonly found in fermented milk, three strains of L. paracasei showed positive PMA-qLAMP results, and the melting temperature was approximately 82.4°C. There was a linear relationship (R2 = 0.9983) between the Ct values and the logarithm of the concentration of viable bacteria. The PMA-qLAMP detection limit for the L. paracasei artificially added to fermented milk was 7.3 × 102 CFU/mL. There was no significant difference between the logarithm values of the concentration of viable L. paracasei of 50 fermented milk samples within shelf life using the PMA-qLAMP and plate count methods (P > 0.01). PMA-qLAMP is specific and accurate for obtaining reliable results faster than when using plate counts.

Strategies to Improve Meat Products' Quality

Meat products represent an important component of the human diet, their consumption registering a global increase over the last few years. These foodstuffs constitute a good source of energy and some nutrients, such as essential amino acids, high biological value proteins, minerals like iron, zinc, selenium, manganese and B-complex vitamins, especially vitamin B12. On the other hand, nutritionists have associated high consumption of processed meat with an increased risk of several diseases. Researchers and processed meat producers are involved in finding methods to eliminate nutritional deficiencies and potentially toxic compounds, to obtain healthier products and at the same time with no affecting the sensorial quality and safety of the meat products. The present review aims to summarize the newest trends regarding the most important methods that can be applied to obtain high-quality products. Nutritional enrichment with natural bioactive plant compounds (antioxidants, dietary fibers) or probiotics, reduction of harmful components (salt, nitrate/nitrite, N-nitrosamines) and the use of alternative technologies (high-pressure processing, cold plasma, ultrasounds) are the most used current strategies to accomplish this aim.

Co-fermentation with Lactobacillus curvatus LAB26 and Pediococcus pentosaceus SWU73571 for improving quality and safety of sour meat

Lactic acid bacteria of Lactobacillus curvatus LAB26 and Pediococcus pentosaceus SWU73571 isolated from traditional sour meat were prepared to a double-starter culture for sour meat processing. The results showed that the counts of total bacteria and lactic acid bacteria in inoculating group reached 9.37 ± 0.11 log cfu/g and 8.73 ± 0.14 log cfu/g on the 30th day, and were higher than those in natural fermentation (7.02 ± 0.11 log cfu/g and 6.93 ± 0.17 log cfu/g). Compared to natural fermentation, the double-starter culture increased the L* and a*values, amino nitrogen content, free amino acid content of sour meat significantly, and lowered the b* value, restrained the coliform count, nitrite, biogenic amines, total volatile basic nitrogen and malondialdehyde in sour meat. Moreover, the pH and water activity were reduced to 3.91 ± 0.01 and 0.831 ± 0.002, respectively. These results proved that the inoculation of double-starter culture could improve the quality and safety of sour meat. This double-starter culture has great potential for application to the manufacture of fermented meat.

Effect of different strategies of Lactobacillus plantarum incorporation in chorizo sausages

BACKGROUND

Chorizo is a high-value Spanish-type dry fermented sausage, highly appreciated by consumers. In this kind of product, Lactobacillus plantarum plays an important role in the fermentation process and can also be considered as a probiotic. The impact of different strategies for incorporating probiotic L. plantarum into the physico-chemical, microbiological, and sensorial characteristics of chorizo sausages was studied. These strategies were: free cells (Cfc); alginate beads (Calg); water-in-oil emulsion (Cwo), and water-in-oil-in-water emulsion (Cwow). Proximate composition, weight loss, pH, a_w , color, and microbiological behavior were evaluated during the ripening (20 days) of chorizo.

RESULTS

The strategy of incorporating L. plantarum significantly affected the proximate composition, pH, and a_w of sausages. However, the traditional red color of chorizo was maintained for all formulations. The incorporation of probiotics as free cells or encapsulated in alginate beads resulted in higher counts of lactic acid bacteria and L. plantarum, lower counts of Enterobacteriaceae, and in acceptable sensory scores.

CONCLUSION

Overall, the quality of chorizo sausages was conditioned by the incorporation strategy, and the addition of probiotics in alginate beads (Calg) was the most effective strategy. © 2019 Society of Chemical Industry.

Antioxidant Activities of Lactic Acid Bacteria for Quality Improvement of Fermented Sausage

Lactobacillus curvatus (SR6) and Lactobacillus paracasei (SR10-1) were assessed for their antioxidant activities and inoculated into sausages to investigate their effects on quality during fermentation. The results showed that L. curvatus SR6 had better DPPH• scavenging activity (59.67% ± 6.68%) and reducing power (47.31% ± 4.62%) and L. paracasei SR10-1 had better OH• scavenging activity (285.67% ± 2.00%) and anti-lipid peroxidation capacity (63.89% ± 0.93%). The superoxide dismutase activity of the cell culture fluid was greater than 47.00 U/mL, and the catalase activity of the cell-free extracts was greater than 1.00 U/mL. In the sausage model, lactic acid bacteria rapidly became the dominant microflora and reduced the moisture content, water activity, nitrite, and pH. The bacteria significantly enhanced the antioxidant activity of the sausage extracts, which improved the sensory characteristics and safety of the sausages. These results illustrate that both strains have excellent antioxidant activities and can be used as antioxidant starters in fermented meat products.

PRACTICAL APPLICATION

The study illustrated the antioxidant and antioxidase activities of Lactobacillus curvatus SR6 and Lactobacillus paracasei SR10-1 and demonstrated the changes in the quality characteristics and antioxidant activities of fermented sausages. The findings provide valuable information for the meat industry on the application of functional starters in fermented meat products.