Suanyu fermentation strains screening, process optimization and the effect of thermal processing methods on its flavor

Elucidating the pattern of flavor evolution during the steaming process of fermented sausages in two dimensions: Strain fermentation and steaming time

This study elucidated the pattern of change in flavor during the steaming of fermented sausages, with a particular focus on the influence of two key factors: Strain fermentation and steaming time. The results indicated that the steaming procedure resulted in a notable loss of water, as well as protein and fat oxidation, in fermented sausages. Additionally, flavor compounds, predominantly aldehydes, esters, and Maillard reaction products, were produced in considerable quantities during the steaming of sausages. Notably, fermented sausages inoculated with LS starter (Lactiplantibacillus plantarum CQ 01107 and Staphylococcus simulans CD 207) exhibited lower levels of oxidation and higher contents of free amino acids and free fatty acids. Furthermore, the textural characteristics of LS sausages during steaming were found to be more favorable, as were the flavor compounds content and sensory scores. For 30-min steaming, LS sausages exhibited lower hardness and chewiness, accompanied by higher levels of esters, ketones and aldehydes, and better sensory scores. These findings demonstrate that starter culture selection (particularly LS strains) and 30-min steaming synergistically optimize flavor profiles, provides a scientific foundation for enhancing the flavor characteristics of fermented sausages throughout their journey from the factory production to the consumer's table.

Microbial interactions between Lactoplantibacillus plantarum and Rhodotorula mucilaginosa in the fermented fish juice system

Lactic acid bacteria and yeasts play important roles in fermented fish products. The present study investigated the interaction between Lactoplantibacillus plantarum and Rhodotorula mucilaginosa in a fermented fish juice system. The results demonstrated that the co-culture of L. plantarum L6 and R. mucilaginosa Y9 significantly increased the maximum specific growth and population of L. plantarum L6, and decreased the lag phase. During microbial interactions, R. mucilaginosa Y9 increased the concentration of soluble proteins and provided L. plantarum L6 with more TCA-soluble peptides. Additionally, these two strains showed co-metabolism of amino acids, such as glutamic acid and aspartic acid. Furthermore, the microbial interaction between two strains influenced the generation of volatile compounds. R. mucilaginosain Y9 removed some fishy-odors compounds, including 1-Octen-3-ol, 1-Hexanol and phthalate esters, but increased the accumulation of aldehyde compounds with unpleasant odors. In addition, co-cultivation promoted the generation of special compounds, such as γ-dodecalactone and 2-pentylfuran, which could improve the flavor quality of fermented fish products.

Effects of synthetic microbial community fermentation on volatile flavor and quality characteristics of ginger pickle

This study aimed to examine the effects of synthetic microbial communities (SynComs) constructed using Leuconostoc mesenteroides LM187, Weissella cibaria WC014, and Lactiplantibacillus plantarum LP184 on the fermentation dynamics and flavor of ginger pickle. In comparison to single-bacterial inoculation, SynComs rapidly reduced the pH, accelerating fermentation. SynCom inoculation increased the final metabolic levels of lactic acid (1194.10 mg/kg), citric acid (95.66 mg/kg), acetic acid (75.19 mg/kg), and malic acid (69.39 mg/kg). It also promoted an increase in the contents of volatile flavor substances and types during the fermentation, particularly eucalyptol, α-terpinene, 1-hexanol, 2,4-di-tert-butylphenol, methyl geranate, and (-)-lavender acetate, imparting floral, sweet, and sour aromas to ginger pickle. Sensory evaluation demonstrated that the appearance, texture, taste, and flavor of pickle fermented with SynComs were superior to those of other pickles fermented with single lactic acid bacteria (LAB). Therefore, the SynComs constructed using L. mesenteroides, W. cibaria, and L. plantarum are promising inoculants for enhancing the flavor and quality of ginger fermentation.

Response surface methodology to optimize the Bacillus subtilis var. sojae semen praeparatum liquid fermentation process for the production of fibrinolytic enzyme

Previously, during the Sojae Semen Praeparatum (SSP, Dandouchi in China) concoction process, three types of fibrinolytic enzyme-producing bacteria were screened and identified: Bacillus subtilis, Stenotrophomonas maltophilia and Micrococcus. The fibrin plate approach was used to measure the fibrinolytic enzyme activity of pure fermentation broth, it was found that fibrinolytic enzyme produced by Stenotrophomonas maltophilia has the highest enzyme activity, followed by Bacillus subtilis and Micrococcus is the lowest. In this study, in order to improve enzyme activity and yield, the response surface method was used to optimize the fermentation conditions, including 6 factors such as nitrogen source, carbon source, initial pH, inoculum amount, loading volume and fermentation temperature. Then, the results showed that: the optional fermentation temperature was determined as 28 ℃, 6% inoculum amount, 30.42 h fermentation time and 20 mL of loading volume in 100 mL erlenmeyer flask. Ultimately, under optimal fermentation conditions, enzyme activity produced by Bacillus subtilis var. SSP was 360.82 IU/mL, which was an increase of 109.68% (1.10 folds) compared to before optimization.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-024-06051-8.

Effects of starters on the quality of fermented fish (Zaoyu): Key microorganisms for coloring, softening, and improving flavor

This study aimed to improve the quality of fermented fish Zaoyu by inoculating different starters (Chuzhai starter, Aroma starter and Sweetness starter), and examining the role of key microorganisms. High-throughput sequencing showed the microbial composition of Aroma starter was similar to Sweetness starter, but both were different from Chuzhai starter. Compared to traditional fermentation, inoculated fermentation with Aroma starter and Sweetness starter strengthened the color of Zaoyu by Maillard reaction and softened the muscle by degrading muscle fibers, endomysium and epicardium. Additionally, the taste and odor of Zaoyu were obviously improved, because the proportion of sweet, umami and aroma compounds increased by 2.51 %, 7.09 %, and 22.94 %, respectively. Correlation analysis combined with metabolic functions showed key microorganisms, such as Trichococcus, Rhizopus, Saccharomycopsis, Saccharomyces, etc., improved the quality mainly by promoting sugar production and conversion, and protein degradation. Overall, Aroma starter and Sweetness starter were superior in improving the quality of Zaoyu.

Combining Sensory Analysis and Flavoromics to Determine How the Maillard Reaction Affects the Flavors of Golden Pomfret Hydrolysates

Enzymatic hydrolysis can enhance the flavor of aquatic products. Nevertheless, the strong fishy odor restricts its utilization in culinary applications. This study is centered on enhancing the flavor of golden pomfret samples by promoting the Maillard reaction (MR) between golden pomfret hydrolysate (GHES) and reducing sugars. The research results demonstrate that the Maillard reaction significantly improves the sensory characteristics of GHES. It prompts the formation of diverse volatile compounds, such as aldehydes, esters, and furans. Simultaneously, it reduces the relative amounts of substances associated with fishy odor, such as 1-Octen-3-ol and Hexanal. Moreover, the Maillard reaction increases the contents of amino acids contributing to umami and sweetness, as well as 5'-nucleotides in the samples, thus enriching their umami flavor profiles. After undergoing the Maillard reaction treatment, the antioxidant capacity of the samples is also significantly enhanced (p < 0.05). This research highlights the potential of the Maillard reaction in improving both the flavor and antioxidant properties of GHES, establishing a theoretical basis for elevating the quality of golden pomfret products.

Integrating metabolite profiles and macrotranscriptomics to explore the flavor improvement mechanisms of fermented oyster hydrolysates with endogenous microbe (Lactobacillus pentosus) inoculation

The study investigates the impacts of indigenous bacterial strains inoculation specifically L. pentosus, on the flavor characteristics, microbial composition, and metabolite profiles of fermented oyster hydrolysates. This research aimed to elucidate potential mechanisms underlying the reduction of off-flavors in fermented hydrolysates. A total of 46 and 57 volatile compounds were detected by GC-MS and GC-IMS in hydrolysates inoculated with different core microbes, respectively. The 9 key volatile compounds detected by GC-MS analysis. (E, E)-2,4-heptadienal, heptanal, octanal, pentanal, and (E)-2-octenal reduced the off-flavor of the fermented oyster hydrolysate. Meanwhile 1-octen-3-ol, 3-octanone, 4-octanone, and (E, Z)-2,6-nonadienal enhanced the direct contribution of desirable flavors. Variation in 16 amino acids, 10 organic acids and 3 nucleotides were monitored to further understand the metabolic changes affecting flavor quality. Moreover, pyruvate decarboxylase [EC 4.1.1.1], phosphomannanase [EC 3.2.1.109], lipoyl-CoA synthetase [EC 6.3.2.4], and arginine kinase [EC 2.7.3.3] were the main microbiologically active enzymes. An increase in the content of aromatic compounds and a decrease in the content of C6-C9 unsaturated aldehydes through Lys, Phe, Asp, Glu, phosphoenolpyruvate, oleic acid, and linoleic acid metabolism pathways improved the flavor of oyster hydrolysates fermented by L. pentosus. This research provides a theoretical basis for leveraging autochthonous microbial fermentation to systematically improve flavor characteristics in fermented products.

Research Progress in the Extraction, Structural Characteristics, Bioactivity, and Commercial Applications of Oat β-Glucan: A Review

Oats (Avena sativa L.) are an important cereal crop with diverse applications in both food and forage. Oat β-glucan has gained attention for its beneficial biological activities, such as reducing cardiovascular risk, preventing diabetes, and enhancing intestinal health. Despite its potential, more comprehensive research is required to explore its preparation, modification, bioactivities, and applications. This review highlights recent advancements in the determination and preparation of oat β-glucan, explores its biological activities and mechanisms, and examines the impact of food processing techniques on its properties. This review is intended to provide a theoretical foundation and reference for the development and application of oat β-glucan in the functional food industry.

Unlocking aroma in three types of vinasse fish by sensomics approach

Vinasse fish (VF), a traditional Chinese food, is unique in flavor. However, the key aroma compounds influencing consumer acceptance of VF remain unclear. In this study, the key aroma compounds in three types of VF were explored by a sensomics approach. The results indicated that a total of 50 aroma compounds were quantified, of which 22 compounds exhibited odor activity values ≥1 were key aroma contributors. Eleven key aroma compounds were further confirmed by recombination and omission experiments. Ethyl hexanoate, 1-octen-3-one, and trans-anethole were mutual key aromas, while eugenol, ethyl heptanoate, (2E)-2-nonenal, and hexanal were distinct aroma markers. Particularly, ethyl heptanoate, γ-nonalactone, and eugenol were newly identified as key aroma compounds in VF. Overall, this study revealed the key aroma compounds and their differences in three types of vinasse fish, which will provide profound insights for comprehensively exploring the formation and target regulation of unique flavor in vinasse fish.

Evaluation of low-temperature ultrasonic marination of pork meat at various frequencies on physicochemical properties, myoglobin levels, and volatile compounds

This study aims to evaluate the pork meat quality after ultrasonic brining at different frequencies, thereby providing a more comprehensive understanding of the effects of ultrasound marination on meat. The texture profile analysis showed that ultrasonic curing at various frequencies significantly improved the textural properties of samples, especially at 26.8 kHz, resulting in a reduction of tenderness, hardness, and chewiness values by 44%, 43%, and 44%, respectively. The cooking loss of samples marinated by ultrasound decreased from 27% without ultrasonic treatment to 22%, indicating a significant improvement in water-holding capacity, while the changes in pH had only a subtle impact on pork quality. Meanwhile, the color of pork became more rosy hue due to decreased L⁎ values and increased a⁎ values, which was mainly attributed to an elevated proportion of oxymyoglobin and reduced metmyoglobin content. Additionally, ultrasonic marination did not exert a negative impact on the oxidation of pork protein and lipids. After roasting, samples marinated by ultrasound exhibited a significantly higher abundance of volatile flavor compounds compared to static marinated meat (with an increase of 16 flavor substances) and fresh pork (with an increase of 24 flavor substances), demonstrating the efficacy of ultrasonic marination in enhancing the overall flavor and taste profile of pork. Consequently, the application of ultrasonic technology holds great potential for the "home kitchen type" rapid marination.

Effects of 'bask in sunlight and dewed at night' on the formation of fermented flavor in shrimp paste after maturation

The purpose of the study was to illustrate the roles of three primary indexes, namely sunlight, ventilation and stirring, in the 'bask in sunlight and dewed at night' technique on the quality of shrimp paste, through a laboratory-scale design. The results showed that changes in the post-ripening fermentation conditions, especially sunlight, was instrumental in the physicochemical properties of the shrimp paste. E-nose and SPME-GC-MS were employed to assess the volatile flavor of post-ripening fermentation. A total of 29 key volatile aroma components played a crucial role in the development of post-ripening flavor in shrimp paste with or without sunlight. Lipidomic analysis revealed that sunlight promoted the oxidative degradation of FA, resulting in the production of a diverse range of flavor compounds that imparted the unique aroma of shrimp paste. The findings of this study will establish a theoretical basic for better control of the post-ripening fermentation of traditional shrimp paste.

Starting with screening strains to construct synthetic microbial communities (SynComs) for traditional food fermentation

With the elucidation of community structures and assembly mechanisms in various fermented foods, core communities that significantly influence or guide fermentation have been pinpointed and used for exogenous restructuring into synthetic microbial communities (SynComs). These SynComs simulate ecological systems or function as adjuncts or substitutes in starters, and their efficacy has been widely verified. However, screening and assembly are still the main limiting factors for implementing theoretic SynComs, as desired strains cannot be effectively obtained and integrated. To expand strain screening methods suitable for SynComs in food fermentation, this review summarizes the recent research trends in using SynComs to study community evolution or interaction and improve the quality of food fermentation, as well as the specific process of constructing synthetic communities. The potential for novel screening modalities based on genes, enzymes and metabolites in food microbial screening is discussed, along with the emphasis on strategies to optimize assembly for facilitating the development of synthetic communities.

Effects of sturgeon oil and its Pickering emulsion on the quality of sturgeon surimi gel

This study aimed to extract sturgeon oil (SO) from the sturgeon head and apply it to sturgeon meat to produce surimi gel. The effects of SO and its Pickering emulsion on the qualities of surimi gel were investigated. The results demonstrated that Pickering emulsions improved the quality deterioration of the gel caused by the direct addition of SO, especially the soy isolate protein (SPI) emulsion and the pea isolate protein (PPI) emulsion. Pickering emulsions contributed to a more uniform and compact network structure of the gel, improved the texture properties, enhanced the freeze-thaw stability, and reduced lipid oxidation. Additionally, compared to the addition of exogenous lipids such as peanut oil and linseed oil, SO and its Pickering emulsion better maintained the characteristic flavor of sturgeon surimi gel. This study provides valuable data and feasible ideas for expanding the utilization of sturgeon by-products and developing new types of surimi gel products.

The Effects of Unconventional Feed Fermentation on Intestinal Oxidative Stress in Animals

Unconventional feed, which is abundant in China, contains anti-nutritional factors and toxins; however, these can be greatly reduced with microbial fermentation, thus improving the nutrient content of the feed, enhancing animal appetites, and ultimately significantly improving the intestinal health and growth performance of animals. When oxidative stress occurs, fermented feed can effectively reduce the damage caused by stress to the gastrointestinal tract, accelerate the removal of gastrointestinal abnormalities, improve the ability to resist intestinal stress, and ensure the efficient production of animals. This review introduces the application of unconventional fermented feed in animal production, and expounds upon the function of unconventional fermented feed in animals with oxidative stress symptoms, so as to provide a theoretical reference for the development and application of unconventional fermented feed in antioxidative stress reduction.

GC-MS, GC-IMS, and E-Nose Analysis of Volatile Aroma Compounds in Wet-Marinated Fermented Golden Pomfret Prepared Using Different Cooking Methods

The cooking method is extremely important for the production of low-salt, wet-marinated, fermented golden pomfret because it strongly influences its flavor components and organoleptic quality. There are also significant differences in flavor preferences in different populations. The present study analyzed differences in the aroma characteristics of wet-marinated fermented golden pomfret after boiling, steaming, microwaving, air-frying, and baking using a combination of an electronic nose, GC-IMS, and SPME-GC-MS. Electronic nose PCA showed that the flavors of the boiled (A), steamed (B), and microwaved (C) treatment groups were similar, and the flavors of the baking (D) and air-frying (E) groups were similar. A total of 72 flavor compounds were detected in the GC-IMS analysis, and the comparative analysis of the cooked wet-marinated and fermented golden pomfret yielded a greater abundance of flavor compounds. SPME-GC-MS analysis detected 108 flavor compounds, and the results were similar for baking and air-frying. Twelve key flavor substances, including hexanal, isovaleraldehyde, and (E)-2-dodecenal, were identified by orthogonal partial least-squares discriminant analysis (OPLS-DA) and VIP analysis. These results showed that the cooking method could be a key factor in the flavor distribution of wet-marinated fermented golden pomfret, and consumers can choose the appropriate cooking method accordingly. The results can provide theoretical guidance for the more effective processing of fish products and the development of subsequent food products.

Multi-omics analysis reveals the microbial interactions of S. cerevisiae and L. plantarum on Suanyu, Chinese traditional fermented fish

S. cerevisiae and L. plantarum play important roles in Suanyu fermentation. This study investigated the interaction between S. cerevisiae and L. plantarum during fermentation and its impact on metabolic pathways. Co-culturing S. cerevisiae and L. plantarum increased pH to 5.72, reduced TVB-N to 9.47 mg/mL, and achieved high utilization rates of sugars (98.9%) and proteins (73.7%). During microbial interactions, S. cerevisiae and L. plantarum produced antibiotics, including phenyllactate and Gentamicin C1a, inhibiting the growth of each other. S. cerevisiae used S-adenosyl-l-methionine to counteract acid production of L. plantarum, establishing dominance in Suanyu fermentation. Microbial interactions influenced carbohydrate and energy metabolism pathways, such as nicotinate and nicotinamide metabolism and purine metabolism. S. cerevisiae significantly impacted gene expression in protein synthesis and cell growth pathways, including ribosome, SNARE interactions, basal transcription factors, and MAPK signaling. These findings offer insights into microbial interactions and metabolic processes during Suanyu fermentation.