Latilactobacillus sakei (L. sakei), widely used as a starter culture in fermented sausages, is a species adapted to meat environments. Its ability to survive for a long time in such products is due to the exploitation of different metabolic pathways to gain energy (hexose and pentose sugar fermentation, amino acids catabolism, etc.). Since L. sakei demonstrates high phenotypic and metabolic strain biodiversity, in this work, a metabolomic approach was used to compare five strains of different origins. They were cultivated in a defined medium with glucose or ribose at two concentrations, and analyzed through nuclear magnetic resonance (¹H-NMR) spectroscopy to monitor amino acid consumptions and accumulation of organic acids and aroma compounds. The results showed that all the strains were able to use arginine, especially when cultivated with ribose, while serine was consumed mainly in the presence of glucose. Aroma compounds (i.e., diacetyl and acetoin) were mainly accumulated in samples with ribose. These aspects are relevant for starter cultures selection, to confer specific features to fermented sausages, and to optimize the fermentations. Moreover, the use of ¹H-NMR allowed the fast identification of different classes of compounds (without derivatization or extraction procedures), providing a powerful tool to increase the knowledge of the metabolic diversity of L. sakei.

Kiwi wine (KW) is tipically made by fermenting juice from peeled kiwifruit, resulting in the disposal of peel and pomace as by-products. However, the peel contains various beneficial compounds, like phenols and flavonoids. Since the peel is edible and rich in these compounds, incorporating it into the fermentation process of KW presents a potential solution to minimize by-product waste. This study compared the aroma and taste profiles of KW from peeled (PKW) and unpeeled (UKW) kiwifruits by combining intelligent sensory technology, GC-MS, and ¹H-NMR. Focusing on aroma profiles, 75 volatile organic compounds (VOCs) were identified in KW fermented with peel, and 73 VOCs in KW without peel, with 62 VOCs common to both. Among these compounds, rose oxide, D-citronellol, and bornylene were more abundant in UKW, while hexyl acetate, isoamyl acetate, and 2,4,5-trichlorobenzene were significantly higher in PKW. For taste profiles, E-tongue analysis revealed differences in the taste profiles of KW from the two sources. A total of 74 molecules were characterized using ¹H-NMR. UKW exhibited significantly higher levels of tartrate, galactarate, N-acetylserotonin, 4-hydroxy-3-methoxymandelate, fumarate, and N-acetylglycine, along with a significantly lower level of oxypurinol compared to PKW. This study seeks to develop the theoretical understanding of the fermentation of kiwifruit with peel in sight of the utilization of the whole fruit for KW production, to increase the economic value of kiwifruit production.

A variety of metabolites contribute to the freshness and taste characteristics of seafood. This study investigated the effects of high hydrostatic pressure (HHP; 400, 500, and 600 MPa) for 10 min) on the metabolome of striped prawn during chilled storage, in relation to microorganisms’ development. All treated samples showed lower viable counts throughout storage compared to the untreated counterparts. The limit of acceptability from a microbiological point of view was extended from 9 to as many as 35 days by 600 MPa treatment. Metabolites were quantified by ¹H-NMR through a targeted-untargeted metabolomic approach. Molecules linked to nucleotides’ degradation and amines’ anabolism suggested an overall freshness improvement granted by HHP. Notably, putrescine and cadaverine were detected only in untreated prawn samples, suggesting the inactivation of degradative enzymes by HHP. The concentration of molecules that influence umami perception was significantly elevated by HHP, while in untreated samples, the concentration of molecules contributing to a sour taste gradually increased during storage. As metabolomics was applied in its untargeted form, it allowed us to follow the overall set of metabolites related to HHP processing and storage, thus providing novel insights into the freshness and taste quality of striped prawn as affected by high hydrostatic pressure.

Sour meat, a traditional fermented meat product, derives its unique attributes from the flavors developed during the fermentation process. This study systematically investigated the dynamic changes in volatile compounds and bacterial succession in pork sour meat during fermentation (0, 15, 30, and 45 days) using a combination of an electric nose (E-nose), an electric tongue (E-tongue), gas chromatography–ion mobility spectrometry (GC-IMS), gas chromatography–mass spectrometry (GC-MS), and 16S rRNA amplicon sequencing. The results showed that the E-nose and E-tongue effectively distinguished samples across fermentation stages. The pork sour meat was analyzed using GC-IMS and GC-MS, which identified 39 and 81 volatile compounds (VOCs), respectively, primarily esters, alcohols, and aldehydes, with esters being most abundant after 45 days of fermentation. A total of 18 and 25 volatile compounds, respectively, were identified by GC-IMS and GC-MS as differential VOCs (p < 0.05, VIP > 1) of the pork sour meat. α-diversity increased in both species’ richness and diversity over the course of fermentation, while β-diversity analysis further differentiated samples across stages. Firmicutes dominated the bacterial community, with Staphylococcus, Lactobacillus, and Weissella as the main genera. Pearson correlation analysis revealed distinct associations between bacteria and volatiles: Staphylococcus was positively associated with butyl acetate-D, ethyl acetate, isoamyl acetate, dihydroactinidiolide, and (E)-2-heptenal, while Lactobacillus and Weissella were positively associated with acetic acid. Additionally, Weissella showed positive correlations with eight volatile compounds: acetic acid, nonanal, benzyl alcohol, ethyl crotonate, isoamyl acetate, dihydroactinidiolide, octanal, and ethyl acetate. This study provides a comprehensive understanding of volatile compound evolution and bacterial succession in pork sour meat, thereby offering a scientific basis for understanding and regulating its flavor quality.

To explore the potential mechanisms underlying the effects of a probiotic in cirrhotic patients, we analyzed the blood metabolome using proton nuclear magnetic resonance (¹H-NMR) spectroscopy in 32 patients with cirrhosis and cognitive dysfunction or falls. Patients were randomized to receive a multistrain probiotic or placebo for 12 weeks. Among the 54 metabolites identified, the only significant changes in the probiotic group were an increase in glutamine, a decrease in glutamate, and an increase in the glutamine/glutamate ratio. In the placebo group, glutamate increased and the glutamine/glutamate ratio decreased. Our results suggest the multistrain probiotic could influence glutamine/glutamate metabolism, increasing the capacity of ammonia detoxification.