The effect of nano/microparticles of bee pollen on the shelf life of high-fat cooked sausage during refrigerated storage.

Sausage is susceptible to oxidative changes in lipids and microbial spoilage due to the presence of water, fat, protein, and vitamins. Bee pollen (BP) as a source of potential antioxidants and antibacterial compounds can effectively prevent lipid peroxidation and microbial spoilage in meat products. The aim of the present study was to investigate the antibacterial and antioxidant activities of BP and the effects of nano/microparticles of bee pollen extract (n/m BP) at a concentration of 125 and 250 mg/100 g meat on the oxidative stability and microbial growth of high-fat sausage during 30 days of storage at 4°C. The formation of BP particles in the nano/micro range was confirmed by scanning electron microscopy. High concentrations of total phenolic compounds (28.26 ± 0.10 mg GAE/g BP) with antioxidant activity (EC50 = 5.4 ± 0.07 mg/mL) were detected in BP. Based on the microdilution assay, the minimum inhibitory concentration of n/m BP for all test bacteria was 1000 (µg/mL) and the minimum bactericidal concentration of n/m BP was 2000 (µg/mL) for Staphylococcus aureus and Bacillus cereus and 4000 (µg/mL) for Escherichia coli and Pseudomonas aeruginosa. The n/m BP treatment (250 mg/100 g meat) showed a higher pH value (p < .05) and lower TBARS values (p < .05) than the ascorbic acid treatment (100 mg/100 g meat) and the control during the storage period. The microbial analysis showed that the addition of n/m BP led to a significant decrease (p < .05) in the total bacterial count, coliforms, S. aureus, and fungal population compared to the other samples. The results show that the addition of n/m BP (125 mg/100 g) can improve the texture, taste, and overall acceptability of the sausage compared to the control sample. In conclusion, this study suggests that BP can replace synthetic antioxidants in high-fat sausages at the nano/microparticle level.

The effect of sourdough, turnips, and butternut squash on the physicochemical and nutritional properties of Doowina functional food during fermentation.

The dairy-cereal-based food, known as Doowina, is one of the traditional fermented foods in Iran. We aimed to improve the health-promoting properties of Doowina by using turnips, butternut squash, and sourdough as a new functional food with high nutritional value and antioxidant activity. Therefore, the physicochemical, microbial, and sensory properties of samples with nutritional supplements (8% turnip and 8% butternut squash) and different concentrations of sourdough (0, 0.5, and 1%) were studied during 0, 3, 6, and 9 days of fermentation time. The results showed that there was no significant difference (p < .05) in the moisture and ash content between the different formulations of Doowina. There was also no significant difference (p < .05) in the phenolic compound content and antioxidant activity of the Doowina samples during the fermentation period. However, the number of lactic acid bacteria (LAB) increased significantly (p < .05) until the 6th day of fermentation, and the protein content decreased significantly (p < .05) in all samples during the fermentation period. According to the results, the samples with butternut squash and sourdough had the highest total phenolic content, the highest antioxidant activity, the highest linoleic acid content, and the highest sensory rating of all samples.

Time-kill kinetic of nano-ZnO-loaded nanoliposomes against Aspergillus niger and Botrytis cinerea.

In vitro antimicrobial activity of nano-ZnO-loaded nanoliposomes at different levels of lecithin:nano-ZnO ratio (5:1, 15:1, and 25:1 w/w) against Aspergillus niger (IBRC-M 30095) and Botrytis cinerea (IBRC-M 30162) was evaluated. Nanoliposome formulations containing nano-ZnO were fabricated through thin-layer hydration sonication and heat methods. The minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of nano-ZnO-loaded nanoliposomes and free nano-ZnO against Aspergillus niger and Botrytis cinerea were determined. The time-kill experiments were performed for each isolate. Results showed that the encapsulation of nano-ZnO in nanoliposome systems significantly enhanced their antimicrobial activities by improving the penetration of ZnO nanoparticles the fungi cell membrane. In vitro antifungal activity of nano-ZnO-loaded nanoliposomes against Aspergillus niger and Botrytis cinerea was increased in thin-layer hydration sonication method compared with the heat method. The log phase for Aspergillus niger and Botrytis cinerea was around 70 h. Adding nano-ZnO-loaded nanoliposomes to the culture medium shortened the log phase for both Aspergillus niger and Botrytis cinerea. The highest antimicrobial activity of nanoliposomes was achieved using nanoliposomes containing the lecithin:nano-ZnO ratio of 25:1 (w/w) as compared to all samples. However, the length of the log phase growth cultures exposed to the nanoliposome formulations prepared by thin-layer hydration sonication method with the lecithin:nano-ZnO ratio of 25:1 (w/w) at MIC and MFC values was 60 and 40 h for both Aspergillus niger and Botrytis cinerea, respectively.

Effects of Cuminum cyminum L. essential oil and its nanoemulsion on oxidative stability and microbial growth in mayonnaise during storage.

The present study aimed to investigate the effects of Cuminum cyminum L. essential oil (CEO) and its nanoemulsion (CEON) on oxidative stability and microbial growth of mayonnaise during storage. The GC analysis indicated that Cuminaldehyde (27.99%), o-Cymene (17.31%), γ-Terpinen (16.67%), and ß-Pinene (9.35%) were the major components of CEO, respectively. The assessments of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) showed that Escherichia coli ATCC 25922 (MBCCEO = 12 and MBCCEON = 6 mg/mL) was the most resistant bacteria, and in contrast, Staphylococcus aureus ATCC 29213 (MBCCEO = 6 and MBCCEON = 3 mg/mL) was the most sensitive bacteria. In the radical-scavenging assay, CEON (IC50 = 5 ± 0.07 µg/mL) exhibited a higher antioxidant activity than CEO (IC50 = 10 ± 0.13 µg/mL). The results showed that applying the MBC of CEO and CEON in mayonnaise led to a significant decrease (p < .05) in acidity, peroxide value, number of acid-resistant bacteria and fungi, and total microbial count compared with the control sample. In conclusion, this study demonstrated that using CEON resulted in oxidative stability, microbial growth control, and desirable sensorial attributes in mayonnaise compared with CEO and control samples.

Discovery of long non-coding RNAs in Aspergillus flavus response to water activity, CO2 concentration, and temperature changes.

Although the role of long non-coding RNAs (lncRNAs) in key biological processes in animals and plants has been confirmed for decades, their identification in fungi remains limited. In this study, we discovered and characterized lncRNAs in Aspergillus flavus in response to changes in water activity, CO2 concentration, and temperature, and predicted their regulatory roles in cellular functions. A total of 472 lncRNAs were identified in the genome of A. flavus, consisting of 470 novel lncRNAs and 2 putative lncRNAs (EFT00053849670 and EFT00053849665). Our analysis of lncRNA expression revealed significant differential expression under stress conditions in A. flavus. Our findings indicate that lncRNAs in A. flavus, particularly down-regulated lncRNAs, may play pivotal regulatory roles in aflatoxin biosynthesis, respiratory activities, cellular survival, and metabolic maintenance under stress conditions. Additionally, we predicted that sense lncRNAs down-regulated by a temperature of 30 °C, osmotic stress, and CO2 concentration might indirectly regulate proline metabolism. Furthermore, subcellular localization analysis revealed that up-and down-regulated lncRNAs are frequently localized in the nucleus under stress conditions, particularly at a water activity of 0.91, while most up-regulated lncRNAs may be located in the cytoplasm under high CO2 concentration.

Gene Networks Analysis of Salmonella Typhimurium Reveals New Insights on Key Genes Involved in Response to Low Water Activity.

Background: When Salmonella enterica serovar Typhimurium, a foodborne bacterium, is exposed to osmotic stress, cellular adaptations increase virulence severity and cellular survival. Objectives: The aim of the gene network analysis of S. Typhimurium was to provide insights into the various interactions between the genes involved in cellular survival under low water activity (aw). Materials and Methods: We performed a gene network analysis to identify the gene clusters and hub genes of S. Typhimurium using Cytoscape in three food samples subjected to aw stress after 72 hours. Results: The identified hub genes of S. Typhimurium belonged to down-regulated genes and were related to translation, transcription, and ribosome structure in the food samples. The rpsB and Tig were identified as the most important of the hub genes. Enrichment analysis of the hub genes also revealed the importance of translation and cellular protein metabolic processes. Moreover, the biological process associated with organonitrogen metabolism in milk chocolate was identified. According to the KEGG pathway results of gene cluster analysis, cellular responses to stress were associated with RNA polymerase, ribosome, and oxidative phosphorylation. Genes encoding RNA polymerase activity, including rpoA, rpoB, and rpoZ, were also significantly identified in the KEGG pathways. The identified motifs of hub DEGs included EXPREG_00000850, EXPREG_00000b00, EXPREG_000008e0, and EXPREG_00000850. Conclusion: Based on the results of the gene network analysis, the identified hub genes may contribute to adaptation to food compositions and be responsible for the development of low water stress tolerance in Salmonella. Among the food samples, the milk chocolate matrix leads to more adaptation pathways for S. Typhimurium survival, as more hub genes were down-regulated and more motifs were detected. The identified motifs were involved in carbohydrate metabolism, carbohydrate transport, electron transfer, and oxygen transfer.

Study of Lactic Acid Bacteria Community From Raw Milk of Iranian One Humped Camel and Evaluation of Their Probiotic Properties.

BACKGROUND: Camel milk is amongst valuable food sources in Iran. On the other hand, due to the presence of probiotic bacteria and bacteriocin producers in camel milk, probiotic bacteria can be isolated and identified from this food product. OBJECTIVES: The objectives of the present research were the isolation and molecular identification of lactic acid bacteria from camel milk and evaluation of their probiotic properties. MATERIALS AND METHODS: A total of ten samples of camel milk were collected from the Golestan province of Iran under aseptic conditions. Bacteria were isolated by culturing the samples on selective medium. Isolates were identified by amplification of the 16S rDNA and Internal Transcribed Spacer (ITS) region between the 16S and 23S rRNA genes by Polymerase Chain Reaction (PCR) and were then screened and grouped by the Amplified Ribosomal DNA Restriction Analysis (ARDRA) method. To evaluate probiotic properties, representative isolates of different ARDRA profiles were analyzed. The antimicrobial activity of Lactic Acid Bacteria (LAB) against Pediococcus pentosaceus, Escherichia coli and Bacillus cereus was examined by the agar diffusion assay. Acid and bile tolerance of isolates were evaluated. RESULTS: A total of 64 isolates were analyzed based on biochemical tests and morphological characteristics. The most frequently isolated LAB was Enterococci. Weissella, Leuconostoc, Lactobacilli and Pediococci were less frequently found. Based on restriction analysis of the ITS, the isolates were grouped into nine different ARDRA patterns that were identified by ribosomal DNA sequencing as P. pentosaceus, Enterococcus faecium strain Y-2, E. faecium strain JZ1-1, E. faecium strain E6, E. durans, E. lactis, Leuconostoc mesenteroides, Lactobacillus casei and Weissella cibaria. The results showed that antimicrobial activity of the tested isolates was remarkable and P. pentosaceus showed the most antibacterial activity. In addition, E. durans, E. lactis, L. casei and P. pentosaceus were selected as probiotic bacteria. CONCLUSIONS: This study revealed the presence of bacteriocin-producing bacteria and probiotic bacteria in camel milk from the Golestan province of Iran.