•Phage PD1 has a short latency, long lytic phase, and high lysis.•Phage PD1 genome contains three lysis-related genes (eRzI homolog, type II holin, and lysozyme).•Phage PD1 reduces P. fluorescens ...populations in milk and grass carp.•Phage PD1 delays the increase in TVB-N values in grass carp.
In order to explore the application prospects of phages for controlling bacterial contamination, a lytic phage Pf17397_F_PD1 (Later abbreviated as PD1) was isolated from fish guts using Pseudomonas fluorescens ATCC 17397 as the host bacterium. The phage displayed short latency (18 min), long lysis period (212 min), and high lysis volume (1.47 × 102 PFU/each cell). It displayed wide temperature (30–70°C) and pH (4–11) tolerance. Genomic comparison revealed a maximum sequence identity of 48.65% between phage PD1 and other identified phages, indicating that PD1 was a new phage. The phage PD1 significantly inhibited the growth of P. fluorescens in milk and grass carp at 4°C and 25°C. Compared to the negative control, bacterial levels in milk stored at 25°C for 48 h were reduced by 2.71 log CFU/mL and 2.84 log CFU/mL at the multiplicity of infection (MOI) of 100 and 1,000, respectively. In contrast, when grass carp were stored at 25°C for 24 h, the bacterial load was reduced by 1.28 log CFU/g and 2.64 log CFU/g compared to the control (MOI of 100 and 1,000). When the phage was applied for preservation of grass carp blocks, total volatile salt nitrogen (TVB-N) values of phage-treated samples increased by 6.8 mg/100 g and 7.5 mg/100 g at MOI of 100 and 1,000, respectively, after 7 days of storage, which was significantly lower than that of the control group (15.83 mg/100 g). This study showed that phage PD1 was a good natural biological antimicrobial agent against P. fluorescens ATCC 17397.
The study aimed to investigate the effect and mechanism of eugenol treatment on fresh-peeled Chinese water chestnuts (CWCs). The results found that eugenol treatment maintained the appearance of ...fresh-peeled CWCs, accompanied by higher L* value, total solids and O
2
contents, as well as lower browning degree, weight loss rate, CO
2
content, a* and b* values. In addition, eugenol treatment significantly reduced the activities of peroxidase, phenylalanine ammonia-lyase, and polyphenol oxidase, as well as the total content of soluble quinone in fresh-peeled CWCs. Meanwhile, fresh-peeled CWCs treated with eugenol showed markedly lower content of total flavonoids, which may be related to yellowing. Furthermore, eugenol treatment suppressed the rates of O
2
·
-
and OH·
-
production as well as the contents of H
2
O
2
and malondialdehyde in fresh-peeled CWCs. During the storage, eugenol treatment not only increased the activities of catalase, superoxide dismutase, ascorbate peroxidase and glutathione reductase as well as the DPPH free radical scavenging rate, but also increased the total phenolics, ascorbic acid and glutathione contents. In summary, eugenol treatment delayed the surface discoloration of fresh-peeled CWCs by improving the antioxidant capacity, inhibiting the phenolic compound metabolism and scavenging ROS, thus effectively maintaining the quality of fresh-peeled CWCs while extending their shelf life.
Lotus (
Gaertn) is a wetland vegetable famous for its nutritional and medicinal value. Phenolic compounds are secondary metabolites that play important roles in the browning of fresh-cut fruits and ...vegetables, and chemical constituents are extracted from lotus for medicine due to their high antioxidant activity. Studies have explored in depth the changes in phenolic compounds during browning, while little is known about their synthesis during the formation of lotus rhizome. In this study, transcriptomic analyses of six samples were performed during lotus rhizome formation using a high-throughput tag sequencing technique. About 23 million high-quality reads were generated, and 92.14% of the data was mapped to the reference genome. The samples were divided into two stages, and we identified 23,475 genes in total, 689 of which were involved in the biosynthesis of secondary metabolites. A complex genetic crosstalk-regulated network involved in the biosynthesis of phenolic compounds was found during the development of lotus rhizome, and 25 genes in the phenylpropanoid biosynthesis pathway, 18 genes in the pentose phosphate pathway, and 30 genes in the flavonoid biosynthesis pathway were highly expressed. The expression patterns of key enzymes assigned to the synthesis of phenolic compounds were analyzed. Moreover, several differentially expressed genes required for phenolic compound biosynthesis detected by comparative transcriptomic analysis were verified through qRT-PCR. This work lays a foundation for future studies on the molecular mechanisms of phenolic compound biosynthesis during rhizome formation.
Salmonella
is a leading cause of foodborne disease and is often associated with the consumption of foods of animal origin. In this study, sixty-six
Salmonella
isolates were obtained from 631 raw meat ...samples purchased at small retail suppliers in Hubei Province, China. The most prevalent
Salmonella
serotypes were Thompson (18.2%) and Agona (13.6%). Frequent antimicrobial resistance was observed for the sulfonamides (43.9%), tetracycline (43.9%), and the β-lactams amoxicillin and ampicillin (36.4% for each). Interestingly, a high incidence of resistance to cephazolin was observed in strains of the most common serotype,
S.
Thompson. Class I integrons were found in 27.3% (18/66) of the isolates and five of these integrons contained different gene cassettes (
aacA4C-arr-3-dfr2, dfrA12-aadA21, aadA2, dfrA12-aadA2, dfr17-aadA5
). Additional antimicrobial resistance genes, including
bla
TEM–1
,
bla
CTX–M–65
,
bla
CTX–M–15
,
qnrB
, and
qnrS
, were also identified among these
Salmonella
isolates. Results of replicon typing and conjugation experiments revealed that an integron with
qnrB
and
bla
CTX–M–15
genes was present on incH12 mobile plasmid in
S.
Thompson strain. Multilocus sequence typing (MLST) analysis revealed 32 sequence types, indicating that these isolates were phenotypically and genetically diverse, among which ST26 (18.2%) and ST541 (12.1%) were the predominant sequence types. The integrons, along with multiple antimicrobial resistance genes on mobile plasmids, are likely contributors to the dissemination of multidrug resistance in
Salmonella
.
The nutritional value of duck meat is well acknowledged due to its low cholesterol and high protein content. Nevertheless, the impacts of deep-frying and baking on its quality characteristics are not ...extensively documented in literature.
The objective of this study is to examine the effects of deep-frying, pre-boilingdeep-frying, baking, and pre-boiling-baking on the quality attributes, water distribution, microstructure, and flavor characteristics of duck jerky.
The findings revealed that the deep-frying group had better quality attributes than the baking, pre-boiling-deep-frying, and pre-boiling-baking groups. The deepfried duck jerky had a higher a* value (4.25) and a lower b* value (5.87), with a more appropriate texture profile, and had the highest comprehensive impression score (5.84). Moreover, the drying rate was faster, and the intensity of the free water and oil signal was significantly elevated in the deep-frying group. The microstructure results indicated that the muscle fibers in the deep-frying group were closely packed, whereas those in the baking group were relatively loose. Furthermore, the GC-IMS test revealed that the deep-fried duck jerky had a wider range of volatile flavor compounds, including 11 unique compounds that were only found in this particular product.
Chilled duck meat is a popularly consumed meat in China but easily perishes at room/low temperature. Kojic acid is usually used as an antimicrobial. This study investigated the sensory scores, total ...bacteria number, and total volatile base nitrogen (TVB-N) value of chilled duck meat under kojic acid treatment during storage. The results presented that kojic acid suppressed the growth of spoilage bacteria and prolonged the shelf-life of chilled duck meat by at least two days. In further investigation, the bacterial community composition was explored through high-throughput sequencing. Pseudomonas spp. were the predominant spoilage bacteria after 6-day storage and were significantly suppressed by kojic acid. Besides, Brochothrix showed drug resistance and became the dominant bacteria in the kojic acid treated sample after 6-day storage. In conclusion, kojic acid maintained the sensorial, chemical, and microbial quality of duck meat stored at low temperatures. Meanwhile, kojic acid enriched the bacteria composition and showed strong antimicrobial activity against Pseudomonas spp.
In this study, “Honghu White Lotus”, “Red Lotus (HH)”, “Hunan Cunshan Lotus (CS)”, “Wuyi Xuanlian”, “Space Lotus 36”, “Fujian Jianning White Lotus (JB)”, “Jiangsu Yangzhou Lotus (JY)”, and “Suzhou ...Dongshan Lotus” were selected as experimental subjects. The lotus seed flesh and lotus plumule of each cultivar were selected for nutritional quality and functional active substance analyses. Comparing different cultivars of lotus seeds, the protein and crude fat contents of JY flesh were the highest at 65.59 mg/g and 13%, respectively. The VC content of JB flesh and lotus plumule is the highest at 41.56 mg/g and 204.29 mg/g, respectively. JB flesh has the lowest soluble sugar content, at 17.87 mg/g, while HB’s lotus plumule and flesh have the highest content, at 33.67 mg/g and 29.62 mg/g, respectively. There was no significant difference in the crude fat content of the flesh and lotus plumule among the eight cultivars. TK flesh and lotus plumule have the highest amylose content, at 23.67 mg/g and 76.81 mg/g, respectively. Among them, the total starch content of JB (476.17 mg/g) was relatively high, whereas its amylose content was only 26.09 mg/g. Lower amylose content makes it less prone to aging. The total phenolic and flavonoid contents of the JY lotus plumule were the highest, at 18.64 and 21.04 mg/g, respectively. The alkaloid content of CS, HH, and JY was relatively high at 20.01, 19.29, and 18.68 mg/g, respectively. These can provide a consultation for the estimation and processing of the nutritional quality of different lotus seeds.
This study investigated the impact of variety and harvest time on the visual appearance, nutritional quality, and functional active substances of six lotus root cultivars: “Xinsanwu”, “Wuzhi No. 2”, ...“Baiyuzhan”, “Huaqilian”, “Elian No. 6”, and “Elian No. 5”. Samples were collected monthly from December 2023 to April 2024. A nutrient analysis revealed a decrease in the water content with a delayed harvest. The total soluble solids and soluble sugar content peaked towards the end and middle-to-late harvest periods, respectively. Starch levels initially increased before declining, while the soluble protein exhibited a triphasic trend with an initial rise, a dip, and a final increase. The vitamin C (Vc) content varied across cultivars. Functional active substances displayed dynamic changes. The total phenolics initially decreased, then increased, before ultimately declining again. The total flavonoid content varied by both cultivar and harvest time. The phenolic acid and flavonoid content mirrored the trends observed for total phenolics and total flavonoids. Gastrodin was the most abundant non-flavonoid compound across all varieties. “Wuzhi No. 2” and “Baiyuzhan” displayed higher levels of functional active substances and starch, while the Elian series and “Xinsanwu” cultivar exhibited a greater content of Vc, soluble sugar, and soluble protein. Specific harvest periods yielded optimal results: “Wuzhi No. 2” (H1 and H5), “Huaqilian” (H2), and “Baiyuzhan” (H3 and H4) demonstrated a high nutrient and functional active substance content. Overall, the lotus roots harvested in period H4 achieved the highest score. Overall, this study provides the foothold for the rapid identification of superior lotus root cultivars and the valorization of lotus root by-products via advanced processing methods. Additionally, it offers valuable insights for market participants and consumers to select optimal varieties and harvest times based on their specific needs.
Browning limits the commercial value of fresh-cut lotus root slices. Melatonin has been reported to play crucial plant roles in growth and development. However, the mechanisms in repressing the ...browning of fresh-cut lotuses are still unclear. In this study, fresh-cut lotus root slices were treated with melatonin, the physical signs of browning were tested, and then the selected samples (0 d, 6 d, 12 d) were used in multiomics analysis. Fresh-cut lotus root slices with a thickness of 4 mm were soaked in a 40 mmol/L melatonin solution for 10 min; then, the slices were packed in pallets and packages and stored at 10 ± 1 °C. The results show that the 40 mmol/L melatonin selected for repressing the browning of lotus roots significantly delayed the decrease in water, total soluble solid content, and Vitamin C, decreased the growth of microorganisms, enhanced total phenolic content, improved total antioxidant capacity, and decreased ·OH, H
O
, and O
· contents. Moreover, this treatment enhanced phenylalanine ammonialyase, polyphenol oxidase, superoxide dismutase, and catalase activities and reduced peroxidase activities and soluble quinones. NnSOD (104590242), NnCAT (104609297), and some NnPOD genes showed a similar transcript accumulation pattern with enzyme activity. It can be seen from these results that exogenous melatonin accelerated an enhancement in the antioxidant system and AsA-GSH cycle system by regulating ROS-metabolism-related genes, thereby improving the capacity to withstand browning and the quality of lotus root slices. The microbiome also showed that melatonin suppressed the fertility of spoilage organisms, such as Pseudomonas, Tolumonas, Acinetobacter, Stenotrophomonas, and Proteobacteria. Metabonomics data uncovered that the metabolites of flavonoid biosynthesis, phenylpropanoid biosynthesis, tyrosine metabolism, and phenylalanine metabolism were involved in the process.
To investigate the effects of crushed water extraction, uncrushed water extraction, crushed alcohol extraction, uncrushed alcohol extraction, pulverized soup post-extraction and unpulverized soup ...extraction on volatile flavor components of Zanthoxylum bungeanum Maxim. and its ability to confer volatile flavor substances to braised duck neck was studied. Gas chromatography-mass spectrometry (GC-MS) and gas chromatography-ion mobility spectrometry (GC-IMS) were used to determine the differences of main volatile flavor components in brine and braised duck neck under different treatment methods. GC-MS results showed that the main aromatic compounds in Zanthoxylum bungeanum Maxim. were alcohols, hydrocarbons, esters and ethers. Water extraction could improve the dissolution of 4-terpineol and other alcohols, and alcohol extraction could improve the dissolution of pyoletene and other substances. Decoction extraction had a better dissolution effect on ethers, and crushing treatment could effectively promote the diss
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