Unfolding microbiota and volatile organic compounds of Portuguese Painho de Porco Preto fermented sausages

Metabolic cross-feeding enhances branched-chain aldehydes production in a synthetic community of fermented sausages

Microbial interactions play an important role in regulating the metabolic function of fermented food communities, especially the production of key flavor compounds. However, little is known about specific molecular mechanisms that regulate the production of key flavor compounds through microbial interactions. Here, we designed a synthetic consortium containing Debaryomyces hansenii D1, Staphylococcus xylosus S1, and Pediococcus pentosaceus PP1 to explore the mechanism of the microbial interactions underlying the branched-chain aldehydes production. In this consortium, firstly, D. hansenii secreted amino acids that promoted the growth of P. pentosaceus and S. xylosus. Specifically, D. hansenii D1 secreted alanine, aspartate, glutamate, glutamine, glycine, phenylalanine, serine, and threonine, which were the primary nutrients for bacterial growth. P. pentosaceus PP1 utilized all these eight amino acids through cross-feeding, whereas S. xylosus S1 did not utilize aspartate and serine. Furthermore, D. hansenii D1 promoted the production of branched-chain aldehydes from S. xylosus and P. pentosaceus through cross-feeding of α-keto acids (intermediate metabolites). Thus, the accumulation of 2-methyl-butanal was promoted in all co-culture. Overall, this work revealed the mechanism by which D. hansenii and bacteria cross-feed to produce branched-chain aldehydes in fermented sausages.

Use of two autochthonous bacteriocinogenic strains as starter cultures in the production of salchichónes, a type of Spanish fermented sausages

In this work, two autochthonous LAB strains (Lactiplantibacillus paraplantarum BPF2 and Pediococcus acidilactici ST6), isolated from spontaneously fermented sausages produced in Spain, were tested to produce Spanish fermented sausages (salchichón) in pilot plants, due to their promising technological and anti-listerial activity. These products were compared with a sample obtained with a commercial starter (RAP) and a spontaneously fermented control sample. Physico-chemical parameters, microbial counts, metagenomic analysis, biogenic amines content and organoleptic profile of the obtained samples were studied to assess the performances of the native starters. In fact, traditional and artisanal products obtained through spontaneous fermentations can represent an important biodiversity reservoir of strains to be exploited as new potential starter cultures, to improve the safety, quality and local differentiation of traditional products. The data underlined that ST6 strain resulted in a final lower percentage if compared with the other LAB used as starter cultures. The use of starters reduced the BA concentration observed in the sausages obtained with spontaneous fermentation and the BPF2 and ST6 strains were able to decrease the level of products rancidity. Moreover, a challenge test against L. monocytogenes were performed. The data confirmed the effectiveness in the inhibition of L. monocytogenes by the two bacteriocinogenic strains tested, with respect to RAP and control samples, highlighting their ability to produce bacteriocins in real food systems. This work demonstrated the promising application in meat industry of these autochthonous strains as starter cultures to improve sensory differentiation and recognizability of typical fermented sausages.

Correlation and Difference between Core Micro-Organisms and Volatile Compounds of Suan Rou from Six Regions of China

Suan Rou (SR), a traditional fermented meat, is widely favored by consumers due to its unique flavor and characteristics. To study the relationship between the core differential micro-organisms and differential volatile organic compounds (VOCs) of SR from six regions of China, high-throughput sequencing (HTS) and gas-chromatography−ion mobility spectrometry (GC-IMS) technologies were used to analyze the correlation between micro-organisms and VOCs in SR from Xiangxi of Hunan, Rongshui of Guangxi, Zunyi of Guizhou, Jinping of Guizhou, Congjiang of Guizhou, and Libo of Guizhou. A total of 13 core micro-organisms were identified at the genus level. Moreover, 95 VOCs were identified in the SR samples by GC-IMS analysis, with alcohols, aldehydes, ketones, and esters comprising the major VOCs among all the samples. The results showed a strong correlation (|r| > 0.8, p < 0.05) between the core differential micro-organisms and differential VOCs, including four bacteria, five fungi, and 12 VOCs. Pediococcus, Debaryomyces, Zygosaccharomyces, and Candida significantly contributed to the unique VOCs of SR.

Evaluation of Hesperidin on Sausages Stuffed in a New Modified Casing during Long-Term Storage—A Preliminary Study

The effects of hesperidin and different casings on pH, moisture content, water-holding capacity, and total viable count (TVC) of sausages stored for 171 days were evaluated by principal component analysis (PCA) and discriminant analysis (DA). Sausages stuffed in a modified casing with treatment B (soy lecithin concentration: 1:30, soy oil concentration: 2.5%, lactic acid concentration: 21 mL/kg NaCl [solid], treated time: 90 min) had a significantly lower pH value (6.89 ± 0.01) at d 31 but higher (6.55 ± 0.03) than that of control casings at d 171 (p < 0.05). Hesperidin plays an important role in antimicrobial property that renders the sausages with modified casing by treatment A (soy lecithin concentration: 1:27.5, soy oil concentration: 1.25%, lactic acid concentration: 19.5 mL/kg NaCl [solid], treated time: 75 min) stable (p > 0.05), with the final TVC of 5.03 ± 0.10 log cfu/g. According to the PCA results, water-holding capacity has a positive correlation to pH. Moisture content was the best discriminator for differentiating sausages with control and modified casings, whilst pH was able to discriminate sausages stored after 138 days from other days.