Ascorbic Acid Changes Growth of Food-Borne Pathogens in the Early Stage of Biofilm Formation

Use of Coffee Roasting By-Products (Coffee Silverskin) as Natural Preservative for Fresh-Cut Fennel Slices

The coffee roasting by-product, coffee silverskin, represents a serious problem in environmental pollution. Still, it is also an interesting source of chemical compounds that can be recovered and used in the food industry to improve the physical, chemical, and sensory properties of a wide range of food products. This study aimed to evaluate, for the first time, the effect of the coffee silverskin extract (CSE), applied as a dipping treatment, in preserving the storage and the qualitative decay of fresh-cut fennel slices during 14 days of storage at 4 °C. The experimental plan evaluated two dipping solutions (5% and 10%) with coffee silverskin extract and compared them with a conventional dipping in 2% ascorbic acid and a control (water). The use of CSE in the dipping of fresh-cut fennel permitted an increase in the phenolic (chlorogenic and caffeic acids) content for up to 14 days, with good sensory acceptability and physico-chemical and microbiological characteristics. To date, no applications of CSE in this form have been reported, nor has any food by-product extract been investigated for the preservation of fresh-cut fennel, which makes this study a novel contribution to the development of sustainable treatments for minimally processed vegetables.

Insight into the role of antioxidant in microbial lignin degradation: Ascorbic acid as a fortifier of lignin-degrading enzymes

BACKGROUND

Microbial-driven lignin depolymerization has emerged as a promising approach for lignin degradation. However, this process is hindered by the limited activity of lignin-degrading enzymes. Antioxidants are crucial for maintaining redox homeostasis in living cells, which can impact the efficiency of enzymes. Ascorbic acid (AA) is well-known for its antioxidant properties, while Trametes versicolor is a commonly used lignin-degrading fungus capable of secreting laccase (Lac) and manganese peroxidase (MnP). Thus, AA was selected as model antioxidant and added into the culture medium of T. versicolor to examine the effect of antioxidants on the activity of lignin-degrading enzymes in the fungus.

RESULTS

The presence of AA resulted in a 4.9-fold increase in the Lac activity and a 3.9-fold increase in the MnP activity, reaching 10736 U/L and 8659 U/L, respectively. This increase in enzyme activity contributed to a higher lignin degradation rate from 17.5% to 35.2%, consistent with observed morphological changes in the lignin structure. Furthermore, the addition of AA led to a reduction in the molecular weights of lignin and an increase in the content of degradation products with lower molecular weight, indicating more thorough degradation of lignin. Proteomics analysis suggested that the enhancement in enzyme activity was more likely to attributed to the reinforcement of AA on oxidative protein folding and transportation, rather than changes in enzyme expression.

CONCLUSIONS

The addition of AA enhanced the performance of enzymes responsible for lignin degradation in terms of enzyme activity, degradation rate, lignin structural change, and product mapping. This study offers a feasible strategy for enhancing the activity of lignin-degrading enzymes in the fungus and provides insights into the role of antioxidant in microbial lignin degradation.

Exploring Methacrylated Gellan Gum 3D Bioprinted Patches Loaded with Tannic Acid or L-Ascorbic Acid as Potential Platform for Wound Dressing Application

To improve wound healing, advanced biofabrication techniques are proposed here to develop customized wound patches to release bioactive agents targeting cell function in a controlled manner. Three-dimensional (3D) bioprinted "smart" patches, based on methacrylated gellan gum (GGMA), loaded with tannic acid (TA) or L-ascorbic acid (AA) have been manufactured. To improve stability and degradation time, gellan gum (GG) was chemically modified by grafting methacrylic moieties on the polysaccharide backbone. GGMA patches were characterized through physicochemical, morphological and mechanical evaluation. Kinetics release and antioxidant potential of TA and AA as well as antimicrobial activity against common pathogens Pseudomonas aeruginosa, Staphylococcus aureus and Escherichia coli in accordance with ISO 22196:2011 are reported. The cytocompatibility of the patches was demonstrated by direct and indirect tests on human dermal fibroblasts (HDF) as per ISO 10993. The positive effect of GGMA patches on cell migration was assessed through a wound healing assay. The results highlighted that the patches are cytocompatible, speed up wound healing and can swell upon contact with the hydration medium and release TA and AA in a controlled way. Overall, the TA- and AA-loaded GGMA patches demonstrated suitable mechanical features; no cytotoxicity; and antioxidant, antimicrobial and wound healing properties, showing satisfactory potential for wound dressing applications.

Poly(ε-Caprolactone)-Based Composites Modified With Polymer-Grafted Magnetic Nanoparticles and L-Ascorbic Acid for Bone Tissue Engineering

The aim of this study was to develop multifunctional magnetic poly(ε-caprolactone) (PCL) mats with antibacterial properties for bone tissue engineering and osteosarcoma prevention. To provide good dispersion of magnetic iron oxide nanoparticles (IONs), they were first grafted with PCL using a novel three-step approach. Then, a series of PCL-based mats containing a fixed amount of ION@PCL particles and an increasing content of ascorbic acid (AA) was prepared by electrospinning. AA is known for increasing osteoblast activity and suppressing osteosarcoma cells. Composites were characterized in terms of morphology, mechanical properties, hydrolytic stability, antibacterial performance, and biocompatibility. AA affected both the fiber diameter and the mechanical properties of the nanocomposites. All produced mats were nontoxic to rat bone marrow-derived mesenchymal cells; however, a composite with 5 wt.% of AA suppressed the initial proliferation of SAOS-2 osteoblast-like cells. Moreover, AA improved antibacterial properties against Staphylococcus aureus and Escherichia coli compared to PCL. Overall, these magnetic composites, reported for the very first time, can be used as scaffolds for both tissue regeneration and osteosarcoma prevention.

Biofilm formation in food industries: Challenges and control strategies for food safety

Various pathogens have the ability to grow on food matrices and instruments. This grow may reach to form biofilms. Bacterial biofilms are community of microorganisms embedded in extracellular polymeric substances (EPSs) containing lipids, DNA, proteins, and polysaccharides. These EPSs provide a tolerance and favorable living condition for microorganisms. Biofilm formations could not only contribute a risk for food safety but also have negative impacts on healthcare sector. Once biofilms form, they reveal resistances to traditional detergents and disinfectants, leading to cross-contamination. Inhibition of biofilms formation and abolition of mature biofilms is the main target for controlling of biofilm hazards in the food industry. Some novel eco-friendly technologies such as ultrasound, ultraviolet, cold plasma, magnetic nanoparticles, different chemicals additives as vitamins, D-amino acids, enzymes, antimicrobial peptides, and many other inhibitors provide a significant value on biofilm inhibition. These anti-biofilm agents represent promising tools for food industries and researchers to interfere with different phases of biofilms including adherence, quorum sensing molecules, and cell-to-cell communication. This perspective review highlights the biofilm formation mechanisms, issues associated with biofilms, environmental factors influencing bacterial biofilm development, and recent strategies employed to control biofilm-forming bacteria in the food industry. Further studies are still needed to explore the effects of biofilm regulation in food industries and exploit more regulation strategies for improving the quality and decreasing economic losses.

Postbiotics: the new horizons of microbial functional bioactive compounds in food preservation and security

In recent decades, consumers, manufacturers, and researchers have been more interested in functional foods, which include probiotics, prebiotics, and postbiotics. Probiotics are live microbes that, when regulated in enough quantities, provide health benefits on the host, while the prebiotics are substrates that host microorganisms selectively use. Postbiotics are metabolites and cell-wall components that are beneficial to the host and are released by living bacteria or after lysis. Postbiotic dietary supplements are more stable than probiotics and prebiotics. Many bioactivities of postbiotics are unknown or poorly understood. Hence, this study aims to present a synopsis of the regular elements and new developments of the postbiotics including health-promoting effects, production, conceptualization of terms, bioactivities, and applications in the field of food safety and preservation. Postbiotics aid in bio preservation and the reduction of biofilm development in food due to their organic acids, bacteriocins, and other antibacterial activities. The present study examines the production of postbiotic metabolites in situ in food and the effects of external and internal food components. The antimicrobial roles, removal of biofilms, and its applications in preservation and food safety have also been discussed. This paper also explored the various aspects like manipulation of postbiotic composition in the food system and its safety measures.

Graphical Abstract

Biodegradable Packaging Based on Poly(vinyl Alcohol) and Carboxymethyl Cellulose Films Incorporated with Ascorbic Acid for Food Packaging Applications

Petroleum-based plastics are used as packaging materials because of their low cost and high availability; however, continuous use of these nondegradable materials especially in the food industry has led to environmental pollution. The present study aimed to synthesize antibacterial and biodegradable films based on natural biopolymers carboxymethyl cellulose (CMC), poly(vinyl alcohol) (PVA), and ascorbic acid (AA) cross-linked in the presence of glutaraldehyde (GA). The films were synthesized in two different concentrations, 60PVA:40CMC:AA and 70PVA:30CMC:AA with a fixed amount of AA. Films with smooth texture and overall uniform thickness were obtained. Fourier transform infrared spectroscopy (FTIR) confirmed the cross-linking between the aldehyde group of GA and hydroxyl of PVA through detection of acetal and ether bridges. The synthesized films were thermally stable in the temperature range of 180-300 °C; however, 70PVA:30CMC:AA showed higher weight loss in this range as compared to the 60PVA:40CMC:AA film. Soil burial test demonstrated that the 60PVA:40CMC:AA film was more degradable (71% at day 15) as compared to the 70PVA:30CMC:AA film (65% at day 15). The films exhibited excellent antimicrobial activity against Gram-positive staphylococcus aureus(inhibition zone of 21 mm) and Gram-negative Escherichia coli (inhibition zone of 15 mm). In comparison, the 60PVA:40CMC:AA film showed better results in terms of high mechanical strength, uniform morphology, higher soil burial degradation, and lower water vapor transmission rate. Therefore, the prepared film could be used as a promising candidate in the food packaging industry.

Evaluation of the Antimicrobial Activity of a Formulation Containing Ascorbic Acid and Eudragit FS 30D Microparticles for the Controlled Release of a Curcumin-Boric Acid Solid Dispersion in Turkey Poults Infected with Salmonella enteritidis: A Therapeutic Model

The selection of components within a formulation or for treatment must stop being arbitrary and must be focused on scientific evidence that supports the inclusion of each one. Therefore, the objective of the present study was to obtain a formulation based on ascorbic acid (AA) and Eudragit FS 30D microparticles containing curcumin-boric acid (CUR-BA) considering interaction studies between the active components carried out via Fourier transform infrared spectrometry (FTIR) and differential scanning calorimetry (DSC) to minimize antagonistic effects, and comprehensively and effectively treat turkey poults infected with Salmonella enteritidis (S. enteritidis). The DSC and FTIR studies clearly demonstrated the interactions between AA, BA, and CUR. Consequently, the combination of AA with CUR and/or BA should be avoided, but not CUR and BA. Furthermore, the Eudragit FS 30D microparticles containing CUR-BA (SD CUR-BA MP) showed a limited release of CUR-BA in an acidic medium, but they were released at a pH 6.8-7.0, which reduced the interactions between CUR-BA and AA. Finally, in the S. enteritidis infection model, turkey poults treated with the combination of AA and SD CUR-BA MP presented lower counts of S. enteritidis in cecal tonsils after 10 days of treatment. These results pointed out that the use of an adequate combination of AA and CUR-BA as an integral treatment of S. enteritidis infections could be a viable option to replace the indiscriminate use of antibiotics.

Vitamin C fortification: need and recent trends in encapsulation technologies

The multifaceted role of vitamin C in human health intrudes several biochemical functions that are but not limited to antioxidant activity, homoeostasis, amino acid synthesis, collagen synthesis, osteogenesis, neurotransmitter production and several yet to be explored functions. In absence of an innate biosynthetic pathway, humans are obligated to attain vitamin C from dietary sources to maintain its optimal serum level (28 μmol/L). However, a significant amount of naturally occurring vitamin C may deteriorate due to food processing, storage and distribution before reaching to the human gastrointestinal tract, thus limiting or mitigating its disease combating activity. Literature acknowledges the growing prevalence of vitamin C deficiency across the globe irrespective of geographic, economic and population variations. Several tools have been tested to address vitamin C deficiency, which are primarily diet diversification, biofortification, supplementation and food fortification. These strategies inherit their own advantages and limitations. Opportunely, nanotechnology promises an array of delivery systems providing encapsulation, protection and delivery of susceptible compounds against environmental factors. Lack of clear understanding of the suitability of the delivery system for vitamin C encapsulation and fortification; growing prevalence of its deficiency, it is a need of the hour to develop and design vitamin C fortified food ensuring homogeneous distribution, improved stability and enhanced bioavailability. This article is intended to review the importance of vitamin C in human health, its recommended daily allowance, its dietary sources, factors donating to its stability and degradation. The emphasis also given to review the strategies adopted to address vitamin c deficiency, delivery systems adopted for vitamin C encapsulation and fortification.

Alleviating the virulence of Pseudomonas aeruginosa and Staphylococcus aureus by ascorbic acid nanoemulsion

The high incidence of persistent multidrug resistant bacterial infections is a worldwide public health burden. Alternative strategies are required to deal with such issue including the use of drugs with anti-virulence activity. The application of nanotechnology to develop advanced Nano-materials that target quorum sensing regulated virulence factors is an attractive approach. Synthesis of ascorbic acid Nano-emulsion (ASC-NEs) and assessment of its activity in vitro against the virulence factors and its protective ability against pathogenesis as well as the effect against expression of quorum sensing genes of Pseudomonas aeruginosa and Staphylococcus aureus isolates. Ascorbic acid Nano-emulsion was characterized by DLS Zetasizer Technique, Zeta potential; Transmission Electron Microscopy (TEM) and Fourier transform infrared spectroscopy (FT-IR). The antibacterial activity of ASC-NEs was tested by the broth microdilution method and the activity of their sub-MIC against the expression of quorum sensing controlled virulence was investigated using phenotypic experiments and RT-PCR. The protective activity of ASC-NEs against P. aeruginosa as well as S. aureus pathogenesis was tested in vivo. Phenotypically, ASC-NEs had strong virulence inhibitory activity against the tested bacteria. The RT-PCR experiment showed that it exhibited significant QS inhibitory activity. The in vivo results showed that ASC-NEs protected against staphylococcal infection, however, it failed to protect mice against Pseudomonal infection. These results suggest the promising use of nanoformulations against virulence factors in multidrug resistant P. aeruginosa and S. aureus. However, further studies are required concerning the potential toxicity, clearance and phamacokinetics of the nanoformulations.

Incorporation of plasma Vitamin C levels to modified nutritional risk in critically ill score as the novel Vitamin C nutritional risk in critically ill score in sepsis subjects as an early predictor of multidrug-resistant bacteria: A prospective observational study

Background

On intensive care unit (ICU) admission, it is difficult to predict which patient may harbor multidrug-resistant (MDR) bacteria. MDR is the nonsusceptibility of bacteria to at least one antibiotic in three or more antimicrobial categories. Vitamin C inhibits bacterial biofilms, and its incorporation into the modified nutritional risk in critically ill (mNUTRIC) scores may help predict MDR bacterial sepsis early.

Methods

A prospective observational study was conducted on adult subjects with sepsis. Plasma Vitamin C level was estimated within 24 h of ICU admission, and it was incorporated into the mNUTRIC score (designated as Vitamin C nutritional risk in critically ill [vNUTRIC]). Multivariable logistic regression was performed to determine if vNUTRIC was an independent predictor of MDR bacterial culture in sepsis subjects. The receiver operating characteristic curve was plotted to determine the vNUTRIC cutoff score for predicting MDR bacterial culture.

Results

A total of 103 patients were recruited. The bacterial culture-positive sepsis subjects were 58/103, with 49/58 culture-positive subjects having MDR. The vNUTRIC score on ICU admission in the MDR bacteria group was 6.71 ± 1.92 versus 5.42 ± 2.2 in the non-MDR bacteria group (P = 0.003, Independent Student's t-test). High vNUTRIC score ≥6 on admission is associated with MDR bacteria (P = 0.042 Chi-Square test), and is a predictor of MDR bacteria (P = 0.003, AUC 0.671, 95% confidence interval [0.568-0.775], sensitivity 71%, specificity 48%). Logistic regression showed that the vNUTRIC score is an independent predictor of MDR bacteria.

CONCLUSION

High vNUTRIC score (≥6) on ICU admission in sepsis subjects is associated with MDR bacteria.

Oligomers of Carboxymethyl Cellulose for Postharvest Treatment of Fresh Produce: The Effect on Fresh-Cut Strawberry in Combination with Natural Active Agents

In this study, oligomers of carboxymethyl cellulose (O-CMC) were used as a new postharvest treatment for fresh produce. The oligomers were prepared by green and cost-effective enzymatic hydrolysis and applied to prevent spoilage and improve storability of fresh-cut strawberries. The produce quality was improved by all formulations containing O-CMC in comparison to the control, as indicated by the decrease in decay incidence, weight loss (min ~2-5 times less), higher firmness, microbial load decrease, better appearance, and sensorial quality of the fruits. Natural resources: ascorbic acid, gallic acid, and vanillin were further added to enhance the beneficial effect. O-CMC with vanillin was most efficient in all of the tested parameters, exhibiting the full prevention of fruit decay during all 7 days of refrigerated storage. In addition, fruits coated with O-CMC vanillin have the smallest weight loss (%), minimum browning, and highest antimicrobial effect preventing bacterial (~3 log, 2 log) and yeast/mold contaminations. Based on the obtained positive results, O-CMC may provide a new, safe, and effective tool for the postharvest treatment of fresh produce that can be used alone or in combination with other active agents.

Chemical Stability of Ascorbic Acid Integrated into Commercial Products: A Review on Bioactivity and Delivery Technology

The L-enantiomer of ascorbic acid is commonly known as vitamin C. It is an indispensable nutrient and plays a key role in retaining the physiological process of humans and animals. L-gulonolactone oxidase, the key enzyme for the de novo synthesis of ascorbic acid, is lacking in some mammals including humans. The functionality of ascorbic acid has prompted the development of foods fortified with this vitamin. As a natural antioxidant, it is expected to protect the sensory and nutritional characteristics of the food. It is thus important to know the degradation of ascorbic acid in the food matrix and its interaction with coexisting components. The biggest challenge in the utilization of ascorbic acid is maintaining its stability and improving its delivery to the active site. The review also includes the current strategies for stabilizing ascorbic acid and the commercial applications of ascorbic acid.

Evaluation of antibacterial activity of vitamin C against human bacterial pathogens

Now a day's multidrug resistance phenomenon has become the main cause for concern and there has been an inadequate achievement in the development of novel antibiotics to treat the bacterial infections. Therefore, there is an unmet need to search for novel adjuvant. Vitamin C is one such promising adjuvant. The present study was aimed to elucidate the antibacterial effect of vitamin C at various temperatures (4°C, 37°C and 50°C) and pH (3, 8, and 11), against Gram-positive and Gram-negative bacteria at various concentrations (5-20 mg/ml) through agar well diffusion method. Growth inhibition of all bacterial strains by vitamin C was concentration-dependent. Vitamin C significantly inhibited the growth of Gram-positive bacteria: Bacillus licheniformis (25.3 ± 0.9 mm), Staphylococcus aureus (22.0 ± 0.6 mm), Bacillus subtilis (19.3 ± 0.3 mm) and Gram-negative bacteria: Proteus mirabilis (27.67 ± 0.882 mm), Klebsiella pneumoniae (21.33±0.9 mm), Pseudomonas aeruginosa (18.0 ± 1.5 mm) and Escherichia coli (18.3 ± 0.3 mm). The stability of vitamin C was observed at various pH values and various temperatures. Vitamin C showed significant antibacterial activity at acidic pH against all bacterial strains. Vitamin C remained the stable at different temperatures. It was concluded that vitamin C is an effective and safe antibacterial agent that can be used in the future as an adjunct treatment option to combat infections in humans.

Biopreservative efficacy of grape (Vitis vinifera) and clementine mandarin orange (Citrus reticulata) by-product extracts in raw ground beef patties

Beef patties were treated with 450 μg/g of extracts from grape (Vitis vinifera) seeds (GSE), pomace (GPE) or orange (Citrus reticulata) pomace (OPE) and compared to negative (no extract; CTR) and positive (sodium metabisulphite; SMB) controls for their effect on colour, lipid and protein oxidation and bacterial growth under simulated retail display conditions (4 °C) for 9 d, and sensory quality. Antioxidant activity and redness of beef patties increased in the order of CTR < OPE = GPE < GSE < SMB. The order of thiobarbituric acid reactive substances and carbonyl values were CTR > GPE = OPE > GSE > SBM, while that of bacterial counts were CTR > GSE = GPE > OPE > SMB. Retail display period had significant effect on all the shelf-life parameters. Overall, intensity of aroma, beef-like aroma and flavour in beef patties were highest in OPE. Results suggested that GSE and OPE could be commercially valorised as natural antioxidants and antibacterials in beef patties, respectively.