Free Amino Acid Composition Research Articles

Lactobacillus fermented chickpeas: Improving dough process quality and biscuit nutritional value

This study aimed to examine the impact of lactobacillus fermented chickpeas (LFC) on dough quality and assess their application potential in biscuits. The results of rheological properties showed that LFC significantly increased the storage modulus (G') and loss modulus (G'') of the dough, with a greater increase in G'. The textural analysis showed that the LFC significantly increased the hardness of the dough before and after fermentation. In the low-field NMR analysis, LFC enhanced the bound water content of the dough and reduced the mobility of the water molecules. Furthermore, the network structure of gluten proteins was weakened by LFC, resulting in more exposed starch. In vitro protein digestibility increased by 28.01% at the gastric end and 11.76% at the intestinal end of LFC-biscuits as compared to chickpea biscuits. It was associated with lactobacilli fermentation reducing phytic acid and trypsin inhibitor activity in chickpeas. Moreover, the protein content of the biscuits has been increased (33.26%) and their free amino acid composition has been optimized. The hardness, brittleness, and specific volume of biscuits were significantly enhanced by LFC, with well sensory acceptance. These findings will enrich the theory of lactobacilli fermentation of legumes and inspire its application in baked foods.

Comparative extraction of antioxidant proteins from whole frogs (Rana ridibunda Pollas).

The forest frog (Rana ridibunda Pollas) is a traditional medicinal source rich in active protein compounds. In order to extract these compounds, six extraction methods were employed, including freeze-thaw and stirring techniques. Three different solvents were utilized in this process: 0.15 M sodium chloride (NaCl), 0.05 M phosphate buffer (PB), and 0.05 M phosphate-buffered saline (PBS). The objective was to identify the most effective extraction method. The extraction efficiencies, protein content, structure, and physicochemical properties of the extracts were compared. Additionally, antioxidant activity and free amino acid composition were analyzed. The highest-scoring extract, denoted as M1, obtained through freeze-thaw extraction using 0.15 M NaCl, exhibited an extraction rate of 7.79 ± 0.71% and a protein content of 60.36 ± 2.12%. M1 also showed antioxidant activity against DPPH˙, ABTS+˙, and ˙OH free radicals, with IC50 values of 0.41, 0.41, and 0.39 mg mL-1, respectively. The freeze-thaw extraction method utilizing 0.15 M NaCl has been identified as effective for extracting proteins from dried forest frogs, confirming their potential as a source of antioxidant proteins for scientific research and application.

Brevibacterium enzymes as biological tools for ochratoxin A detoxification in dairy foods

The origin of ochratoxin A (OTA) in cheeses is mainly due to mould growth during the ripening process, and to a lesser extent, to the use of OTA-contaminated milk in cheese production. Bacterial smear-ripened cheeses developed a smear microbiota on their rind during ripening that greatly contributes to its typical aroma and texture. Bacteria from the Brevibacterium genus belong to the typical smear microbiota of cheeses. Type strains from Brevibacterium species frequently isolated from cheese and milk products were able to transform OTA into much less toxic ochratoxin α (OTα) and L-phenylalanine. Protein searches allowed the identification of a protein annotated as amidohydrolase in these OTA-degrader Brevibacterium strains. The OTA-hydrolytic activity of the identified amidohydrolase was demonstrated by the heterologous production of this protein from B. linens DSM 20425T (BlOTA). In vitro assays revealed that BlOTA transformed OTA into less toxic OTα, as well as ochratoxin B. When compared with other previously described OTA-degrading amidohydrolases, BlOTA exhibited optimal activity at a higher pH (8.0), while showing similar high temperature for optimal activity (55 °C) and thermostability; in addition, a clear preference for substrates with Phe, Tyr or Leu amino acid residues at the C-terminal position was clearly observed. BlOTA efficiently detoxifies OTA-contaminated bovine milk, without provoking changes on its free amino acid composition. Moreover, in silico predictions revealed that BlOTA is a non-allergenic, non-antigenic, and poorly immunogenic protein. Therefore, the QPS status possessed by cheese-Brevibacterium species, as well as the characteristics exhibited by BlOTA, make them suitable tools for the biological detoxification of OTA in dairy and food products.

Targeted metabolomics analysis of fatty acids in lamb meat for the authentication of paper mulberry silage as a substitute for alfalfa silage

BackgroundThe paper mulberry (Broussonetia papyrifera L.) is a valuable source of woody forage that can be used for ruminants, such as goat and lambs. However, there is limited knowledge about how paper mulberry silage affects carcass characteristics, meat physicochemical attributes, amino acid and unsaturated fatty acids in Hu lambs compared to alfalfa silage. The objective of this experiment was to investigate the impact of substituting alfalfa silage with paper mulberry silage on the slaughter performance, meat quality, free amino acid and fatty acid composition in muscles of Hu lambs.ResultsThirty 60-day-old male Hu lambs with 17.13 ± 0.26 kg body weight were randomly allocated into paper mulberry silage (30% of total mixed ration) and alfalfa silage (30% of total mixed ration) treatment, and the feeding trial lasted 70 days. The results indicated no significant differences in all measurements (P > 0.05). However, compared to the group fed with alfalfa silage, the group fed with paper mulberry silage exhibited a reduction in meat drip loss (P < 0.05) without any notable effect on meat nutrients (P > 0.05). Targeted metabolomics analysis revealed that feeding paper mulberry silage led to decreased levels of certain bitter amino acids, such as valine, leucine, isoleucine, tryptophan, and phenylalanine (P < 0.05). Furthermore, the consumption of paper mulberry silage significantly augmented the levels of monounsaturated and polyunsaturated fatty acids, particularly n6-polyunsaturated fatty acids (C18:2n6, C20:3n6, C20:4n6, etc.), in meat.ConclusionsSubstituting paper mulberry silage for alfalfa in the daily diet of Hu lambs not only has no detrimental effect on animal performance but also improves meat unsaturated fatty acid composition.Graphical

Enhanced antioxidant activities, polyphenols, flavonoids, and free amino acid contents of Nelumbo nucifera bee pollen via high hydrostatic pressure treatment

ABSTRACT The aim of the present study was to address the effect of high hydrostatic pressure (HHP) on bioactive compounds and antioxidant activity of Nelumbo nucifera (Lotus) bee pollen (LBP). The total phenolic contents (TPC) and free amino acids were determined and flavonoid composition was identified by UPLC-Triple-TOF-MS. Five analytical methods including DPPH, ABTS, reducing power, FRAP, and silver nanoparticles antioxidant capacity were used for the antioxidant activity analysis. The results revealed a significant increase in the TPC and free amino acid compositions after HHP treatment. The DPPH, ABTS, reducing power, FRAP, and AgNPAC of the extracted fractions were augmented by over 13.94, 2.9, 2.68, 85, and 2.6 times, respectively. PCA analysis showed a strong correlation between TPC, some distinct flavonoids, and antioxidant activities. These results indicated that HHP enhances the antioxidant activity of LBP via increase in amino acids, TPC, and some flavonoids such as Licoagrone, Kuwanon K, Cyanidin 3-rutinoside, etc.

Effect of protease reaction conditions on volatile compounds generated in Maillard reaction products from soy protein hydrolysates

Maillard reaction products (MRPs) produced by heating protease-catalyzed soy protein hydrolysates (SPHs) with cysteine and ribose can generate meat-like flavors. However, the impact of protease reaction conditions on the volatile compound composition of MRPs has not been thoroughly investigated. In this study, seven SPHs were prepared using two proteases, flavourzyme and trypsin, over reaction times of 10, 120, and 1440 min. The volatile compound compositions, including sulfur-containing compounds, aldehydes, pyrazines, and furans, of the seven SPHs and the corresponding seven MRPs varied according to the protease reaction conditions and the Maillard reaction. Differences in pH, free amino acid composition, and peptide composition were responsible for these variations. Notably, soy-derived peptides containing unique cysteine sequences, such as PGCPST, DETICT, ECQIQK, and HCQR, were significantly reduced during the Maillard reaction, suggesting that these sequences may serve as precursors to volatile compounds.

Serum-Free Medium Supplemented with Haematococcus pluvialis Extracts for the Growth of Human MRC-5 Fibroblasts.

Experiments are increasingly performed in vitro; therefore, cell culture technology is essential for scientific progress. Fetal bovine serum (FBS) is a key cell culture supplement providing growth factors, amino acids, and hormones. However, FBS is not readily available on the market, has contamination risks, and has ethical concerns. This study aimed to investigate Haematococcus pluvialis extracts (HE) as a potential substitute for FBS. Therefore, we assessed the effects of HE on cell maintenance, growth, and cycle progression in human lung fibroblasts (MRC-5). Cell progression and monosaccharide, fatty acid, and free amino acid compositions were analyzed using cell cycle analysis, bio-liquid chromatography, gas chromatography, and high-performance liquid chromatography, respectively. The results of nutritional profiles showed that the extracts contained essential amino acids required for synthesizing non-essential amino acids and other metabolic intermediates. Furthermore, most of the components present in HE were consistent with those found in FBS. HE enhanced cell viability and regulated cell cycle phases. Additionally, the interaction between growth factor cocktails and HE significantly improved cell viability, promoted cell cycle progression, and activated key cell cycle regulators, such as cyclin A and cyclin-dependent kinases 1 (CDK1). Our findings suggest that HE have considerable potential to substitute FBS in MRC-5 cell cultures and have functional and ethical advantages.

Elaborating the Atmospheric Transformation of Combined and Free Amino Acids From the Perspective of Observational Studies

AbstractProteinaceous matter (PrM) is a substantial component of bioaerosols. Although numerous studies have examined the characteristics and sources of PrM in the atmosphere, its interactions with atmospheric oxidants remain uncertain. A 1‐year observation of PrM characteristics in PM2.5 was performed in both urban Nanchang (eastern China) and suburban Guiyang (southwestern China), respectively. Glycine was the dominant free amino acid (FAA) species in urban Nanchang. In contrast, proline dominated both total free amino acids (FAAs) and total combined amino acids (CAAs) in suburban Guiyang. We found that oxidative degradation can significantly promote the release of FAAs, especially glycine, from CAAs in Nanchang. The controlled experiment on protein oxidation by hydroxyl radical suggested that the contribution of free glycine to the total FAA fraction tended to increase during the oxidative degradation of CAAs, supporting the predominance of glycine in FAAs in Nanchang and most previous observations. The composition of FAAs was mainly influenced by primary sources in suburban Guiyang with weak atmospheric degradation of PrM. These results suggest that the degradation of aerosol PrM by atmospheric oxidants can be responsible for the difference in FAA composition between the biosphere and the atmosphere, and also imply that the oxidative degradation of aerosol PrM may be a potential source of secondary organic nitrogen compounds in aerosols. Thus, this study can improve the current understanding of the composition characteristics of PrM in the biosphere and the atmosphere, as well as the liquid phase reactions of proteinaceous compounds with atmospheric oxidants.

Valorization of Saithe (Pollachius virens) Residuals into Protein Hydrolysates-Silaging as Preservation Technology.

Silaging can be used as preservation technology to valorize currently discarded raw material into protein hydrolysate on board deep-sea vessels. The aim of this study was to investigate the effect of sorting and raw material freshness on the quality and yield of protein hydrolysates obtained through silaging of saithe (Pollachius virens) viscera. Additionally, the effect of using acid-containing antioxidants was tested. Out sorting of the liver prior to silaging resulted in slightly higher hydrolysate yields. The hydrolysates with the highest protein contents were obtained from silages made from fresh raw materials (day 0), and the content decreased significantly after longer storage of the raw material (2-3 days at 4 °C). Storage of the raw material for 1 day did not affect the quality. However, a significantly higher degree of hydrolysis (DH), content of free amino acids (FAA), and total volatile basic nitrogen (TVB-N) were obtained when raw materials were stored for 3 days. The FAA composition was influenced by the raw material's freshness, with increases in free glutamic acid and lysine and a decrease in free glutamine after longer storage. None of the studied parameters were significantly affected by out sorting of liver or the addition of antioxidants. Overall, the results indicate that the whole fraction of the viscera can be utilized without reducing the quality of the hydrolysate and that the raw material should be stored for a maximum of 1 day prior to preservation to optimize the quality.

Comprehensive analysis of botanical origin and amino acid composition of bee pollen samples from various regions of Turkey

This study aimed to investigate the botanical diversity in bee pollen and amino acid composition of Turkish bee pollen samples collected from different regions. The monofloral bee pollen samples belonged to three different plant families: Asteraceae, Fabaceae, and Ranunculaceae. Additionally, Agean, Central Anatolian, Black Sea, and Marmara Regions have monofloral bee pollen samples with higher than 85% pollen frequency. The free amino acid (FAA) composition and content of the bee pollen samples were analyzed, with the essential amino acids comprising 13.13–18.28% of the total amino acid content. The Central Anatolian region displayed the highest ratio of essential amino acids, and the Aegean region exhibited a more diverse profile of FAA. Principal Component Analysis was performed to evaluate the variation in the data, with the eigenvalues of the two factors explaining 68.58% of the total variability. Moreover, cluster analysis revealed distinct dendrograms based on palynological characteristics and FAA composition.

Contribution of Gamma-Aminobutyric Amino Acid and Free Amino Acids to Low-Salt Whole-Wheat Bread through the Addition of Spice Extracts-An Approach Based on Taste Quality.

Given the link between excessive salt consumption and hypertension, reducing salt levels in bread, an important staple food in Japan, is essential. γ-Aminobutyric acid (GABA) has a salty taste-enhancing effect in vivo, and its production is influenced by the type of spice extract in vitro. However, the effects of spices on GABA levels, total free amino acid composition, and taste quality in whole-wheat bread remain unclear. Therefore, this study aimed to investigate whether the addition of spice extracts, which do not affect bread flavor and taste, can increase the GABA level in low-salt whole-wheat bread and whether free amino acid content affects the taste quality of bread using an automatic home bread maker. Through free amino acid composition analysis and sensory testing, we evaluated the influence of six spice extracts on the composition of free amino acids, including GABA, in whole-wheat bread. We found that cumin and anise extracts were effective in increasing the GABA level to approximately twice that in whole-wheat bread. Moreover, both the preference and saltiness of the bread were favorable, indicating that these extracts are useful for reducing the salt content of whole-wheat bread. This study provides a theoretical basis for guiding industrial production.

Selenium-Chelating Peptide Derived from Wheat Gluten: In Vitro Functional Properties.

The efficacy of selenium-chelating polypeptides derived from wheat protein hydrolysate (WPH-Se) includes enhancing antioxidant capacity, increasing bioavailability, promoting nutrient absorption, and improving overall health. This study aimed to enhance the bioavailability and functional benefits of exogenous selenium by chelating with wheat gluten protein peptides, thereby creating bioactive peptides with potentially higher antioxidant capabilities. In this study, WPH-Se was prepared with wheat peptide and selenium at a mass ratio of 2:1, under a reaction system at pH 8.0 and 80 °C. The in vitro antioxidant activity of WPH-Se was evaluated by determining the DPPH, OH, and ABTS radical scavenging rate and reducing capacity under different conditions, and the composition of free amino acids and bioavailability were also investigated at various digestion stages. The results showed that WPH-Se possessed significant antioxidant activities under different conditions, and DPPH, OH, and ABTS radical scavenging rates and reducing capacity remained high at different temperatures and pH values. During gastrointestinal digestion in vitro, both the individual digestate and the final digestate maintained high DPPH, OH, and ABTS radical scavenging rates and reducing capacity, indicating that WPH-Se was able to withstand gastrointestinal digestion and exert antioxidant effects. Post-digestion, there was a marked elevation in tryptophan, cysteine, and essential amino acids, along with the maintenance of high selenium content in the gastrointestinal tract. These findings indicate that WPH-Se, with its enhanced selenium and amino acid profile, serves as a promising ingredient for dietary selenium and antioxidant supplementation, potentially enhancing the nutritional value and functional benefits of wheat gluten peptides.

L-carnitine can promote the growth performance of rotifers (Brachionus rotundiformis) by improving their feeding behavior and nutrient composition

Rotifer are important food resources in aquaculture hatcheries, and several studies have shown that L-carnitine (LC) can promote the growth performance of rotifers. The aim of this study was to investigate the nature of beneficial effects of LC on rotifer Brachionus rotundiformis. The feeding behavior of rotifers were evaluated at different LC concentrations (0, 1, 10 and 100 mg L−1). Meanwhile, the effects of LC on growth performance, free LC content, amino acid and fatty acid composition of rotifers were analyzed. The results indicated that LC (10 and 100 mg L−1) treatments significantly improved the filtration and ingestion rates of rotifers fed microalgae or baker’s yeast, In addition, LC (10 and 100 mg L−1) not only significantly accumulated in rotifers, but also significantly improved the rotifer growth performance. After 48 h of LC treatment, the rotifer population density significantly increased. Concerning the biochemical composition of rotifers, 100 mg L−1 LC can increase the carbohydrates content, decrease the protein and lipid content in the rotifers. And the LC treatment could significantly decrease the total SFA content of rotifers, while significantly increase the total HUFA content of rotifers. Moreover, the levels of LC supplementation were positively correlated with the contents of Thr, Gly, Ala, Leu, Tyr, Phe, Lys, His, Arg and Pro in rotifers. Overall, adding LC could not only accumulate in rotifers, but also promote the growth performance of rotifers by improving their feeding behavior and their nutritional value.

Changes in water-soluble taste compounds of tilapia (Oreochromis niloticus) fillets subjected to different thawing methods during long-term frozen storage.

The taste of fish is highly dependent on the composition of free amino acids (FAAs) and nucleotides. The present study aimed to investigate the effect of long-term frozen storage periods (-18 °C, up to 6 months) and thawing methods [water thawing (WT, 25 °C), air thawing (AT, 25 °C), and chilled air thawing (CAT, 4 °C)] on the taste quality of tilapia (Oreochromis niloticus) fillets. The results showed that increase in bitter FAAs of CAT samples was 150.57% at 6 months of storage, which was lower than that of AT and WT. Glycine was the most abundant FAA and CAT maintained the highest sweet FAAs (249.90 mg/100 g). Additionally, the inosine monophosphate (IMP) of CAT samples were 1.18 and 1.09 times higher than that of WT and AT, respectively, at a frozen period of 6 months. In particular, the increase in equivalent umami concentration (EUC) values ranged from 24.25% to 103.16% in the three groups during the first 2 months. Data from principal component analysis (PCA) and orthogonal partial least-squares discrimination analysis (OPLS-DA) indicated that the taste quality was highly correlated with high levels of FAAs, hypoxanthine inosine (HxR) and hypoxanthine (Hx) as the storage time progressed. In general, CAT is beneficial in maintaining the taste quality of tilapia fillets during frozen storage, and frozen durations for 2 months enhances the umami flavor. This study provides useful information for the preservation of frozen aquatic products during the storage and thawing, and enrich the theoretical knowledge of the flavor chemistry of fish products. © 2024 Society of Chemical Industry.

The effect of soluble gas stabilization and high-pressure processing on rehydrated dried salt-cured cod vacuum packaged in bio-based bags.

This study evaluates the combination of soluble gas stabilization (SGS) and high-pressure processing (HPP) as hurdle technology on rehydrated clip fish (dried salt-cured cod) packaged in bio-based materials. The factors studied include SGS/non-SGS, pressure at 400MPa/600 MPa (5 min, 8–9 °C) and vacuum packaging with conventional/bio-based material. Stored over 48 d at 4 °C, the investigated parameters were drip loss, water and protein content, free amino acid (FAA) composition, colour, texture, pH and microbiological shelf life. Results revealed minimal differences in quality between packaging materials. The SGS-treated samples gave higher drip loss, lower water but higher protein and FAA content, and a softer texture. Nevertheless, adding CO2 prior to HPP significantly extended the product's microbiological shelf life compared to only HPP. Therefore, using a more environmentally friendly bio-based packaging material is feasible while undergoing mild treatments like the combination of SGS and HPP at a lower treatment pressure for shelf-life extension.

A Data-Driven Approach to Sugarcane Breeding Programs with Agronomic Characteristics and Amino Acid Constituent Profiling.

Sugarcane (Saccharum spp. hybrids) and its processed products have supported local industries such as those in the Nansei Islands, Japan. To improve the sugarcane quality and productivity, breeders select better clones by evaluating agronomic characteristics, such as commercially recoverable sugar and cane yield. However, other constituents in sugarcane remain largely unutilized in sugarcane breeding programs. This study aims to establish a data-driven approach to analyze agronomic characteristics from breeding programs. This approach also determines a correlation between agronomic characteristics and free amino acid composition to make breeding programs more efficient. Sugarcane was sampled in clones in the later stage of breeding selection and cultivars from experimental fields on Tanegashima Island. Principal component analysis and hierarchical cluster analysis using agronomic characteristics revealed the diversity and variability of each sample, and the data-driven approach classified cultivars and clones into three groups based on yield type. A comparison of free amino acid constituents between these groups revealed significant differences in amino acids such as asparagine and glutamine. This approach dealing with a large volume of data on agronomic characteristics will be useful for assessing the characteristics of potential clones under selection and accelerating breeding programs.

Molecular composition and sources of free amino acids in atmospheric aerosols from Mt. Tai and a nearby city

Amino acids (AAs) are involved in the global nitrogen cycle and are important components of nitrogenous organic aerosols. Protein and free amino acid (FAA) concentrations in total suspended particulate (TSP) and their major emission sources were investigated in spring and autumn at Mount Tai (Mt. Tai) on the North China Plain and the nearby city named Liaocheng. There were significant spatial and seasonal differences in protein and FAA concentrations, with rainfall producing lower concentrations. For chiral isomers of AAs, there were significant diurnal differences in D/L-Methionine (Met), which was probably due to FAA source differences caused by regional valley winds and background winds. The high D/L-aspartic acid (Asp) and D/L-glutamine (Glu) concentrations may be indicative of the important contributions of chunk and honeycomb coal combustion. Stable nitrogen isotope analyses revealed that plant debris, soil dust, and biomass burning were important sources of glycine (Gly). Biomass burning, as well as chunk and honeycomb coal combustion, produced large amounts of L-arginine (Arg). Soil dust was the dominant source of FAAs for both Mt. Tai and Liaocheng, while biomass burning contributed more in autumn, and the proportional contribution of plant debris increased in spring.

Taurine prevented the decline of fillet quality and muscle antioxidant capacity in on-growing grass carp (Ctenopharyngodon idella) fed non-fishmeal diet

Taurine is abundantly present in fishmeal, while plant protein sources typically contain minimal to no taurine. This disparity in taurine content may explain variations in fish quality traits caused by the dietary substitution of fishmeal with plant protein sources. This research explored whether taurine supplementation to non-fishmeal (NFM) diet could improve fillet quality and muscle antioxidant capacity in grass carp. A total of 540 fish (255.74 ± 0.65 g) were distributed among six groups. One of them was provided with a fishmeal (FM) diet, while the remaining five groups received NFM diets, formulated with incremental concentrations of crystalline taurine (0, 0.5, 1.0, 1.5, 2.0 g/kg) for 60 days. Our data showed that, in comparison with the un-supplemented group, the optimal taurine supplementation to NFM diet yielded the following findings: (1) increased fillet nutritional values by improving crude protein content, free amino acid and fatty acid compositions; (2) improved fillet physicochemical properties by improving water holding capacity (WHC), tenderness, and preventing pH decline; (3) enhanced antioxidant enzymes activities and gene expressions through nuclear factor-erythroid 2-related factor 2 (Nrf2) signaling pathway. Additionally, this optimal NFM diet showed to be competitive with FM diet in terms of fillet quality. According to quadratic regression curves of ROS production and polyunsaturated fatty acids (PUFA) content, the optimal taurine supplementation levels in NFM diet for on-growing grass carp were 1.12 and 1.18 g/kg diet, respectively.

Analysis of Free Amino Acid Composition and Honey Plant Species in Seven Honey Species in China.

Honey is well-known as a food product that is rich in active ingredients and is very popular among consumers. Free amino acids (FAAs) are one of the important nutritional components of honey, which can be used not only as a nutritional indicator of honey but also as an indicator of plant source identification. In this study, the contents of 20 FAAs in seven types of honey from 11 provinces in China were examined for the first time. The 20 FAAs were analyzed by ultra-performance liquid chromatography-mass spectrometry/mass spectrometry (UPLC-MS/MS). By analyzing 93 honey samples from seven types of honey, the FAAs were found to range from 394.4 mg/kg (linden honey) to 1771.7 mg/kg (chaste honey). Proline ranged from 274.55 to 572.48 mg/kg, and methionine was only present in some of the linden honey, chaste honey, acacia honey, and rape honey. Evaluated by amino acid principal component analysis, multifloral grassland honey had the highest overall evaluation score, acacia and jujube honey were the most similar, while chaste honey was the least similar to the other types of honey. In addition, DNA was extracted from 174 Xinjiang grassland honey samples and different plant leaves for PCR and sequencing to identify the species of nectar plants. As a result, 12 families and 25 species of honey plants were identified. The results confirmed the diversity of FAAs in dissimilar types and sources of honey. This study provides a reference for expanding honey quality standards and verifying the authenticity of honey.

Insights into the fish protein degradation induced by the fish-borne spoiler Pseudomonas psychrophila and Shewanella putrefaciens: From whole genome sequencing to quality changes

The aim of this study is evaluating the protein degradation capacity of specific spoilage organisms (SSOs) Pseudomonas psychrophila and Shewanella putrefaciens in fish flesh during chilled storage and revealing the underlying genes by whole-genome sequencing (WGS). Biochemical and physical tests were performed on fish flesh inoculated with P. psychrophila and S. putrefaciens individually, including textural properties, myofibrillar fragmentation index, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) profiles, free amino acid composition, total volatile basic nitrogen (TVB-N), trichloroacetic acid (TCA) soluble peptides, and muscle microstructure. Results showed that P. psychrophila and S. putrefaciens exhibited a strong capacity for decomposing the fish protein, and the deterioration of fish flesh texture was primarily attributed to P. psychrophila. The genes from SSOs associated with the production of proteases were identified by whole genome sequencing and serine protease may be the primary enzyme secreted by SSOs involved in the degradation of fish protein. Therefore, the present study has shed light on the mechanisms of protein degradation induced by SSOs, thereby offering valuable insights for the development of effective quality control strategies.