Kokumi taste, a sensory attribute that enhances flavor complexity, continuity, and mouthfulness without being a basic taste, has gained significant scientific attention. This review synthesizes advances in kokumi peptide research, focusing on their flavor-enhancing mechanisms, receptor interactions (notably calcium-sensing receptors), natural sources, and food applications. We critically evaluate global research progress and key debates, such as receptor synergy mechanisms and limitations of current flavoring mechanism. Future directions emphasize establishing a global kokumi peptide database, developing artificial intelligence-driven prediction platforms, improving in vivo validation, and optimizing industrial-scale production. This review aims to provide a theoretical foundation for food flavor science and to facilitate the integration of kokumi peptides into the development of functional foods and flavor enhancers.

In order to explore the bacterial community diversity and structure in Xuanwei ham with partial replacement of NaCl by KCl, the V3–V4 region of the 16S rRNA gene of bacteria on and in Xuanwei ham with 0% (control), 30%, 40%, 50% and 60% NaCl replacement by KCl was analyzed by high-throughput sequencing on an Illumina MiSeq platform, and the differences in the structure, composition and diversity of bacterial communities in the five ham samples were compared. The results showed that a total of 257777 sequences and 6153 operational taxonomic units (OTU) were obtained from the surface samples and 248102 sequences and 5704 OTU from the interior samples. Bacterial abundance in the ham differed with the level of KCl replacement, but the dominant bacterial phyla in the surface and interior samples were Proteobacteria and Firmicutes for all replacement groups. Partial substitution of NaCl by KCl increased the relative abundance of Proteobacteria in and on the ham, which reached maximum at substitution level of 40% and significantly higher than that in the control group (P < 0.05). The bacterial community structure was highly similar among the replacement groups. The abundance and diversity of bacterial community on the ham were decreased, while those in the ham were not significantly changed by KCl substitution.

As a new type of umami agent, umami peptides can have a synergistic effect with other umami substances in addition to their own flavor. The current research on umami peptides mainly focuses on their extraction, isolation and identification, but the formation mechanism and taste mechanism of umami peptides are still unclear. This article reviews the preparation, separation and identification methods of umami peptides, the factors affecting flavor presentation, the umami evaluation methods, and the application of umami peptides, in order to provide a scientific and theoretical basis for further in-depth research on umami peptides.

Umami peptides from an aqueous extract of Wuding chicken meat were separated and purified by sequential ultrafiltration, gel filtration chromatography (GPC) and reversed-phase high performance liquid chromatography (RP-HPLC). Sensory evaluation was performed to find the fractions with the strongest umami taste, and then the umami peptides were identified by nano-high performance liquid chromatography-tandem gas chromatography (Nano-HPLC-MS/MS) and synthesized by and solid phase synthesis. Moreover, the sequence and taste characteristics of the umami peptides were further analyzed. The results showed that eight peptides with molecular masses ranging from 365.20 to 1735.92 Da were isolated and identified. Among them, LDF, FVT and DLAGRDLTDYLMKIL exhibited significant umami intensity, with thresholds ranging from 0.062 to 0.250 mg/mL, indicating that they are the key umami components of Wuding chicken meat.

Dry-cured ham, produced through long-term curing, fermentation and ripening, is rich in bioactive substances and has good sensory characteristics. In the traditional production process of dry-cured ham, nitrate or nitrite is often added to obtain a stable color. However, nitrite reacts with secondary amines to produce carcinogenic nitrosamines, which have attracted extensive attention. Research has found that zinc protoporphyrin Ⅸ contributes mainly to the red color of Parma ham, cured without added nitrate or nitrite. This paper summarizes the rescent progress in research on the red pigment in dry-cured ham with or without added nitrate, focusing on the formation mechanism of Zn protoporphyrin Ⅸ in nitrate-free dry-cured ham. The purpose of this review is to provide a scientific theoretical basis for the color regulation of dry-cured ham.

In order to explore the chemical nature of red pigment in Nuodeng ham, the red pigment was extracted with 75% acetone aqueous solution and purified using a C₁₈ solid phase extraction column, and its chemical structure was characterized by using ultraviolet-visible (UV-Vis) spectroscopy, fluorescence spectroscopy and ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS), Fourier transform infrared (FTIR) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy. The UV-Vis spectrum showed a strong absorption peak at 416 nm and two weakly symmetrical absorption peaks at 546 and 584 nm, which are characteristic of metalloporphyrins. When it was excited at 420 nm, the red pigment exhibited a strong fluorescence emission peak at 590 nm and a weak fluorescence emission peak at 644 nm, which highly coincided with those of Zn protoporphyrin Ⅸ (ZnPP) standard, indicating that the metal ions in the porphyrin ring were zinc ions. ZnPP was detected by UPLC-MS/MS in both positive (m/z 625.1779 [M+H]⁺) and negative ion (m/z 623.1614 [M-H]^–) modes, and the stretching vibrations of characteristic functional groups on the porphyrin ring such as –CH₃, –CH₂–, C=O, –C–OH in carboxyl groups, C–H on olefin and porphyrin ring C=N were observed in the FTIR spectrum. In addition, the ¹H-NMR results of the red pigment were consistent with the structure of the target compoundZnPP. Therefore, the red pigment in Nuodeng ham was identified as ZnPP. The results of this study provide a theoretical basis for the color regulation of Nuodeng ham.

The internal microbial diversity and small molecular metabolites of Nuodeng ham in different processing years (the first, second and third year sample) were analyzed by high-throughput sequencing technology and gas chromatography-time of flight mass spectrography (GC-TOF-MS) to study the effects of microorganisms and small molecular metabolites on the quality of ham in different processing years. The results showed that the dominant bacteria phyla of Nuodeng ham in different processing years were Proteobacteria and Firmicutes, the dominant fungi phyla were Ascomycota and Basidiomycota, while Staphylococcus and Aspergillus were the dominant bacteria and fungi of Nuodeng ham, respectively. Totally, 252 kinds of small molecular metabolites were identified from Nuodeng ham in different processing years, and 12 different metabolites were screened through multivariate statistical analysis. Further metabolic pathway analysis showed that 23 metabolic pathways were related to ham fermentation, of which 8 metabolic pathways had significant effects on ham fermentation (Impact > 0.01, P < 0.05). The content of L-proline, phenyllactic acid, L-lysine, carnosine, taurine, D-proline, betaine and creatine were significantly positively correlated with the relative abundance of Staphylococcus and Serratia, but negatively correlated with the relative abundance of Halomonas, Aspergillus and Yamadazyma.

The quality characteristics of dry-cured hams from different regions of Yunnan province were studied by analyzing five types of Yunnan dry-cured hams (Xuanwei ham, Sanchuan ham, Nuodeng ham, Saba ham, and Heqing ham) using headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) and headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS). The analysis aimed to identify different volatile organic compounds (VOCs) in the dry-cured ham samples. Forty-one VOCs were qualitatively characterized by HS-GC-IMS from dry-cured ham samples, of which Nuodeng ham and Saba ham had similar fingerprint profiles and contained higher levels of aldehydes and alcohols. Meanwhile, a total of 12 qualitatively differential characteristic markers were screened by the PLS-DA model. Furthermore, 128 main VOCs were identified by HS-SPME-GC-MS, of which 26 differential characteristic markers were screened by the PLS-DA model. HCA analysis showed that the VOCs of Sanchuan ham were different from those of the other four dry-cured hams due to the unique processing. These results can contribute to a more comprehensive understanding of the flavor characteristics of dry-cured hams from different regions of Yunnan.