Search Results (907)

This study aims to screen out high-yield protease lactic acid bacteria (LAB) from cheese and analyze the flavor and functional characteristics of their fermentation of corn protein hydrolysate (CPH). Lacticaseibacillus rhamnosus ZYN-71 and Limosilactobacillus fermentum ZYN-76 were isolated and screened by traditional biological methods. Then, the two strains synergistically fermented CPH, and it was found that the scavenging rate of DPPH, ·OH, and O²⁻· and the chelating ability of Fe²⁺ of the fermented CPH increased by 22.85%, 3.82%, 63.37%, and 43.27%, respectively. Meanwhile, the solubility, water-holding capacity, oil-holding capacity, foaming property, foam stability, emulsification property, and emulsification stability had also been improved to varying degrees. The aroma of the CPH after fermentation mainly consisted of aldehydes (20.2%) and nitrogen heterocyclic compounds (19.4%), and the content of off-flavor components was reduced. LAB fermentation effectively improves the practical problems existing in the current application of corn proteolytic products. This research can provide a research basis for corn protein-related products. Full article

Fu tea is a unique microbially fermented tea from China, and has two types. The primary distinction between these two types—Fu brick tea (FBT) and Fu loose tea (FLT)—is that FBT is compressed into bricks, whereas FLT is maintained as loose leaves. To investigate the differences in the chemical composition and sensory characteristics between the two types of Fu tea, this study utilized samples produced from the same batch of raw dark tea material to ensure comparability. Multiple analytical approaches were applied, including main active component analysis, sensory flavor evaluation, metabolomics, and differential characteristic component analysis. These methods were employed to comprehensively compare and characterize the two tea types. The results showed that compared to FBT, FLT exhibited a longer-lasting fungal flower aroma and a mellower taste. Furthermore, the quantity of Eurotium cristatum in FLT was 56.7% higher than that in FBT, indicating a significant difference. Untargeted ultrahigh-performance liquid chromatography–mass spectrometry was used to screen metabolites in Fu tea samples, and after multivariate statistical analysis, 12 differential metabolites were finally identified, including phenolic acids and their derivatives, coumarins and their derivatives, phenylpropanoids, and flavonoids and their glycosides. Subsequently, a targeted UHPLC-QQQ-MS/MS-based method was established and validated for the main differential metabolites, phenolic acids and catechins. The results indicated that gallic acid, catechin, and epicatechin can serve as characteristic markers for distinguishing between FBT and FLT. Notably, the content of gallic acid in FLT was 168.6% higher than that in FBT. These findings elucidate the impact of the pressing process on Fu tea, provide guidance for discriminating between FBT and FLT, and are significant for quality control in the industrial production of Fu tea. Full article

Sparkling wine production involves secondary alcoholic fermentation, during which carbon dioxide is trapped, creating effervescence and enhancing sensory complexity. This study evaluated the impact of Torulaspora delbrueckii and Lachancea thermotolerans yeast species using free and immobilized cells in secondary fermentation of sparkling wine, in comparison with Saccharomyces cerevisiae. Immobilized S. cerevisiae enabled faster refermentation compared to free cells, while immobilization resulted in a slower process in non-Saccharomyces strains. Biomass monitoring showed stable viable cells for immobilized S. cerevisiae during fermentation, while non-Saccharomyces strains showed a consistent reduction. Volatile profiles were positively influenced by immobilization using S. cerevisiae strains, which produced a constant increase in key aroma compounds, such as geraniol and ethyl acetate, throughout fermentation. Non-Saccharomyces strains contributed to enhanced fruity and floral aromas with variations in volatiles during refermentation. Sparkling wines fermented with immobilized L. thermotolerans were noted for ripe fruit aromas, while T. delbrueckii increased floral notes. S. cerevisiae fermentations showed higher acidity and balanced structure. These findings highlight the influence of yeast species and the yeast immobilization procedures in secondary fermentation, modulating fermentation dynamics and aroma development, and offer a promising strategy to tailor sparkling wine quality and sensory complexity. Full article

Objectives: The primary objective of this study was to investigate the effects of Macrococcus caseolyticus isolated from Chinese bacon on the quality of Chinese-style sausages. Methods: The physicochemical properties and volatile flavor compounds (VOCs) of sausages inoculated with M. caseolyticus at different concentrations (10⁵, 10⁶, and 10⁷ CFU/g) were investigated. VOCs were detected using gas chromatography–ion mobility spectrometry (GC-IMS). Results: The sausages inoculated with M. caseolyticus showed progressive decreases in Aw, total volatile base nitrogen (TVB-N), malondialdehyde and carbonyl content during fermentation compared to the control sausage. A total of 90 VOCs were identified based on GC-IMS analysis, including 20 esters, 17 aldehydes, 22 alcohols, 12 ketones, 5 acids compounds, and 14 other compounds. M. caseolyticus-inoculated sausages exhibited elevated levels in alcohols and aldehydes, while the content of ketones was reduced compared to the control sausage. Multivariate statistical analysis indicated the significant differences in volatile flavor profiles among the sample and control sausages. Notably, seven VOCs in sausages, including 1-octen-3-ol, isoamyl alcohol, heptanal, hexanal, methyl 2-methylbutyrate, ethyl isovalerate and 2-pinene, were identified as the key aroma compounds (ROAV ≥ 1). Conclusions: The fermented sausages inoculated with different concentrations of M. caseolyticus exhibited significant differences in VOCs. This study provides the support for employing M. caseolyticus to improve the overall quality and flavor profile of Chinese-style sausage. Full article

In this study, we investigated the impact of two native strains of Starmerella bacillaris, used both in pure culture and in a co-inoculation with Saccharomyces cerevisiae, on the volatile profile of a chemically defined fermented model must. The focus of this study was the production of monoterpenes and sesquiterpenes and their potential sensory contributions. Geraniol and linalool were detected in all fermentations with Starmerella bacillaris, in ranges of 26.7–43.9 µg/L and 34.3–41.3 µg/L, respectively, independent of the inoculation strategy used. Both strains produced concentrations above their respective odour thresholds of 20 µg/L and 25.5 µg/L. Odour activity value (OAV) analysis confirmed that fermentations with Starmerella bacillaris, particularly under co-inoculation conditions, generated the highest OAVs for these monoterpenes. Citronellol was only detected in mixed fermentations, while nerolidol and farnesol isomers were produced in variable amounts, depending on the strain and inoculation strategy, at concentrations below the odour threshold. These findings demonstrate the ability of Starmerella bacillaris to facilitate de novo biosynthesis of linalool, geraniol, and sesquiterpenes during alcoholic fermentation—in the case of linalool and geraniol, at concentrations exceeding their respective odour thresholds—highlighting the biotechnological potential of these native strains to enhance aroma in wines, particularly those made from neutral grape varieties. Full article

This study investigated the effects of fermentation temperatures (22 °C, 25 °C, 28 °C) and concentrations of grape juice Brix (26 °, 29 °, 32 °) on the physicochemical and aroma profiles of Musalais wine, a traditional fermented alcoholic beverage from Xinjiang, China. The results indicated that higher fermentation temperatures (28 °C) increased total acidity (TA) and residual sugar content (RSC), whereas lower temperatures (22 °C) resulted in higher pH, phenolic content, and anthocyanin content. Ethanol content reached its peak at 25 °C, particularly in Musalais wines produced from 29 Brix of concentrated grape juice. GC-IMS analysis identified 50 volatile organic compounds (VOCs), with esters (30%), alcohols (22%), and ketones (12%) dominating the aroma profile. Wines fermented at 22 °C exhibited the most complex VOC profiles, characterized by fruity esters (ethyl propanoate) and caramel-like ketones (4-methyl-2-pentanone). In contrast, fermentation at 28 °C produced simpler alcohol-dominated aroma profiles. Multivariate analysis (PCA and PLS-DA) confirmed distinct clustering based on temperature, with 19 key markers (ethyl 2-methylpentanoate, 3-octanone) differentiating the Musalais wines. Correlation analysis revealed strong relationships between ethanol, TA, RSC, and specific VOCs. Hierarchical clustering grouped the wines into two categories: those fermented at 22 °C (fruity and rich in complexity) and those fermented at 25–28 °C (alcoholic and simpler profiles). These findings demonstrate that fermentation temperature significantly impacts Musalais wine quality, with 22 °C being optimal for aroma complexity, while 25 °C provided a balance between ethanol production and antioxidant retention. Brix levels of concentrated grape juice modulated acidity and sweetness. This study offers practical insights for optimizing Musalais wine production through controlled fermentation conditions. Full article

The use of non-Saccharomyces species is gaining momentum in modern winemaking as part of broader efforts to reduce chemical inputs and adapt to climate-driven challenges. In this study, Furmint grapes were harvested at two distinct ripeness levels: an early harvest with healthy berries and a late harvest that included botrytized fruit. Two oenological protocols were compared: a conventional sulphur dioxide-based protocol and an alternative bioprotection-oriented approach that minimized SO₂ additions. Bioprotection was carried out using Metschnikowia pulcherrima, followed by sequential inoculation with Torulaspora delbrueckii and Saccharomyces cerevisiae. Grape-derived tannins (from skin and seed) were also added to inhibit oxidative enzymes such as laccase. Fermentation was monitored using standard analytical techniques, with volatile aroma profiles characterized by HS-SPME-GC-MS. Results showed that harvest timing and botrytization strongly influenced the chemical composition of the wines. Moreover, the treatment protocol had a marked effect on the final sensory profile. Wines produced with the bioprotection-oriented protocol displayed enhanced aromatic complexity, particularly through higher concentrations of esters and higher alcohols. Overall, the alternative protocol involving M. pulcherrima-based bioprotection resulted in wines with more pronounced floral and fruity notes, supporting its potential as a viable strategy for producing expressive wines under evolving climatic conditions. Full article

Vanillin is the compound of great interest to the industry. It is used to augment and enhance the aroma and taste of food preparations and also as a fragrance compound in perfumes and detergents. Currently, majority of the world’s supply consists of chemically synthesized or lignin-derived vanillin. The application of biocatalysis for sustainable manufacturing of food ingredients, pharmaceutical intermediates, and fine chemicals is the key concept of modern industrial biotechnology. The main goal of this research was to conduct optimization procedures aimed at intensifying the microbial hydrolysis process of the lignin-rich plant raw materials and further bioconversion of the released ferulic acid to vanillin. The tests were performed in the solid-state fermentation system with strains selected during the screening stage on agri-food by-products such as brewer’s spent grain. A specially designed single-use bag bioreactor was used to carry out the process on a preparative scale with the most effective strain. The experiment was designed using the RSM, which allowed for an increase in biosynthesis efficiency from 363 mg/kg to 1413 mg/kg (an increase of 389%). The progress of the process was controlled by the use of chromatographic techniques (HPLC) by quantitative determination of vanillin content in the obtained extracts. Full article

The acetic acid fermentation stage is a key determinant of fruit vinegar’s aroma profile. Therefore, this study employed GC-MS, HPLC, E-nose and E-tongue techniques, in conjunction with multivariate statistical analysis, to investigate the dynamic changes of compounds during the acetic acid fermentation process of blackened pear vinegar (BPV), as well as the transformation of volatile and non-volatile aroma-active compounds. Results revealed accumulation of organic acids and esters alongside declines in alcohols, aldehydes, and ketones. Isoamyl acetate, benzaldehyde, and nonanal (OAV > 1) were identified as key aroma contributors (VIP > 1, p < 0.05). Total organic acids significantly increased from 4.82 ± 0.53 mg/mL to 10.29 ± 2.38 mg/mL. Correlation analysis revealed a negative relationship between amino acids and volatile compounds, and this negative correlation suggests a possible precursor–product relationship between them. These findings provide theoretical support for the enhancement of fruit vinegar flavor, as well as the application of blackened fruits. Full article

Volatilomic and sensory analyses of wine are excellent tools for enologists and winemakers when selecting commercial yeast based on the production of metabolites related to desirable wine characteristics. Integrating this holistic approach could lead to the terroir description, characterization, and quality control improvement of the vinification process. Volatilomic and sensory profiles of Cabernet Sauvignon Mexican wines fermented with three commercial yeasts (WLP740, ICVD254, and ICVD80) were obtained using HS-SPME-GC-qTOF/MS and CATA evaluation. A total of 100 volatile compounds were identified, with unique entities per strain. WLP740 wines were rated as high quality, presenting fruity and minty aromas with fewer off-aromas, while ICVD254 wines showed higher levels of compounds associated with off-notes and were rated as low quality. ICVD80 wines were of medium quality, with fruity esters and higher alcohols descriptors. Volatilomic profiles highlighted the role of specific compounds in differentiating strains and sensory attributes, while yeast selection significantly impacts wine aroma and quality. The authors acknowledge the need for further analyses, including an increased sample size, yeast species, diverse vineyards, and vinification processes, which will result in a solid and robust methodology. Full article

In recent years, ultrasound has been integrated into fermentation technology due to its activating effect on microorganisms, and the possible effects of ultrasound-assisted fermentation on the fermentation process, yield and quality of the final product have also attracted attention. This study aimed to reveal the effects of sonication applied before the fermentation on the fermentation process and the quality of fermented black carrot juice. The samples were sonicated at a frequency of 35 kHz and an amplitude of 60% for 0, 5, 15 or 30 min before the fermentation. During the fermentation, the pH, acidity, organic acid profile, ethanol and soluble solid content (SSC), color, turbidity, total lactic acid bacteria (LAB), total mesophilic aerobic bacteria (TMAB) and yeast counts were determined. The amount of SSC in the samples increased at the beginning of fermentation as the sonication time increased. Lactic, acetic and propionic acids were detected in the samples. The amount of lactic acid in all the samples treated with ultrasound was higher than in the control sample and the amounts of acetic acid, propionic acid and ethanol were lower. Ultrasound application caused an increase in the TMAB and yeast counts. A five-minute ultrasound application caused a decrease in the number of LAB, while 15- and 30-min applications caused an increase. Thirty minutes of ultrasound treatment resulted in the reddest fermented black carrot juices with the highest level of color saturation. The most appreciated sample in terms of taste, aroma and general acceptability was the sample subjected to a five-minute ultrasound application. As a result, ultrasound application before fermentation positively supports different quality parameters of fermented black carrot juice and the use of sonication in production can be recommended. Full article

This study used a targeted metabolomics approach to examine changes in metabolites within green tea infusions fermented by G. lucidum (TFG) and evaluate the in vitro antioxidant and lipid-lowering properties of TFG. Fermentation decreased tea polyphenols, flavonoids, caffeine, soluble sugars, theaflavins, and catechins, while increasing free amino acids and theabrownins. The microbial bioconversion process led to the generation of decorated flavonoids, phenolic acids, terpenoids, alkaloids, nucleotides, and amino acids. This process shifted the tea’s taste from bitter and astringent to mellow, primarily due to the transformation of flavonoid glycosides, caffeine, catechins, 5′-guanosine monophosphate, 5′-uridine monophosphate, and theabrownins. Volatile metabolites added woody, floral, sweet, and fruity aromas. Reduced gallic acid and catechins lowered antioxidant activity, whereas increased theabrownins enhanced lipid-lowering activity and imparted a reddish-brown color. These findings indicate that fermentation significantly affects the flavor, aroma, and lipid-lowering ability of green tea infusion. Full article

There is a growing interest within the food industry sector in applying natural and sustainable methods to improve functional, nutritional, and technological properties of foods. In this regard, sprouting and spontaneous sourdough (SD) fermentation, are emerging as promising technological solutions in the bakery industry. The aim of this work was to evaluate the effect of using unsprouted whole-wheat flour (USWF) and sprouted whole-wheat flours (SWFs), obtained under controlled conditions (20 and 25 °C for 24 h), on the chemical and nutritional properties of spontaneous SD and their impact on whole-wheat bread technological quality. SDs were prepared with a dough yield of 200, incubated at 30 °C for 24 h, and refreshed daily for 7 days. In general, an increase in both yeast and lactic acid bacteria counts was observed in all SD samples. All SDs showed reduced α-amylase activity and enhanced contents of free amino acids groups, water-extractable arabinoxylans, total phenolics, and antioxidant capacity, along with lower phytic acid content. Substituting 20% of USWF with SD improved bread volume and crumb softness. Notably, breads made with sourdough prepared from 20% sprouted whole-wheat flour (SWF25) promoted the formation of volatile compounds associated with pleasant aromas, which may increase consumer acceptability. Promising nutritional and sensory advantages could result from combining fermentation and sprouting. Full article

Fruit and sour beers are popular due to their unique sensory characteristics. Owing to changes in physicochemical parameters, mixed culture fermentation is a promising research area. The aim of the study was to evaluate how ethanol and lactic acid fermentation, combined with the addition of berry fruits during the beer production process, influence the physicochemical and sensory characteristics of sour fruit beers. Three worts differing in hopping system were produced: one classic sweet wort and two lacto-fermented. Strawberries or raspberries were added to the young beer. This research showed that acidification of wort, fruit addition, and limiting of hopping time had a positive effect on both technological and sensory characteristics. Despite pH differences, alcohol content in beers was similar (2.52–3.21% v/v). Production method influenced mainly lactic acid (0–2.30 g/L), pH (3.53–4.79), and glycerol (0.83–1.62 g/L) contents. Non-acidified beers had the highest dextrin (17.64–23.13 g/L) and glycerol (1.36–1.62 g/L) levels. The addition of strawberries increased phenolics (205.21–237.03 mg GAE/L), FRAP (0.82–1.17 mmol TE/L), and refreshment sensation, while raspberries mainly enhanced sensory atributes (colour, foam, fruitiness, aroma). Lactic fermentation did not show a clear effect on polyphenol content or antioxidant activity. The research offers practical insights into functional beer development, with its novelty of using mixed fermentation and fruit addition to shape characteristics. Full article

The most notable effects of climate change on wine production are higher alcohol levels, lower acidity and changes to the regions suitable for growing grapes. One solution to acidity problems is the use of Lachancea thermotolerans, a yeast that produces lactic acid during fermentation, albeit at the cost of reduced aromatic complexity. A novel approach to addressing this problem is to use L. thermotolerans to produce wines with a very high acidity, regardless of other parameters, for subsequent blending with a control wine with a naturally low acidity. This achieves a balanced acidity while retaining the organoleptic characteristics of the control wine. This is a novel idea, as L. thermotolerans is not usually used in the final wine. However, the objective from the beginning is to create a blend that combines the best characteristics of the control wine with the improved acidity provided by L. thermotolerans. Base wines were produced by inoculating Saccharomyces cerevisiae 20, 40, or 60 h after inoculating L. thermotolerans. Base wines generally show an increase in lactic acid content and a decrease in certain key aromatic compounds, such as isoamyl acetate, 2-phenylethyl acetate, ethyl hexanoate, and ethyl octanoate. Concentrations of other compounds such as acetaldehyde and higher alcohols also increase. The base wines were then blended with a low-acidity control wine. The resulting blends exhibited higher acidity than the control wine, as well as better aromatic profiles, particularly regarding fruity and green fruit aromatic compounds, compared to base wines. Ten volatile compounds have been correlated with lactic acid production by L. thermotolerans, namely ethyl hexanoate; ethyl butanoate; 2-methylbutanol; ethyl heptanoate; isoamyl acetate; acetaldehyde; isobutanol; 2-phenylethanol; dodecanol; and acetoin. The first five are negatively correlated and the rest are positively correlated. Lastly, sensory analysis revealed that the blends achieved the best balance between acidity and aroma, making them the most popular with tasters. Full article