Search Results (8)

This study evaluates the efficacy of the salts sodium metabisulfite (SMB), ammonium bicarbonate, sodium bicarbonate, and potassium dihydrogen orthophosphate first in vitro against the main postharvest fruit rot fungi, Alternaria alternata, Botrytis cinerea, Penicillium italicum, and Penicillium digitatum. Results showed that 0.2% SMB completely inhibited the mycelium growth of the fungal species. Ammonium bicarbonate and sodium bicarbonate were less effective at 0.2% in inhibiting mycelial growth, ranging from 57.6% to 77.6%. The least effective was potassium dihydrogen orthophosphate. Experiments were also performed in vivo on wounded apples inoculated with the most pathogenic fungus, B. cinerea, and treated with SMB at concentrations of 0.2, 0.5, 1, 2, and 3%, both preventively and curatively. Results based on the decay size showed that SMB, when used as a preventive treatment, had a reduced efficacy, even with the highest concentration. However, this salt proved to be very effective at 0.5% in curative treatment since the decay was completely blocked. Our results suggest that the appropriate concentration of SMB for post-harvest treatment is 0.5% as a curative treatment. On the other hand, the 1% dose induced the onset of phytotoxicity around the wound. To assess the extent of the phytotoxicity reaction, higher concentrations of 1–4% SMB were applied to wounded fruit. Apples and oranges were inoculated or not with B. cinerea and P. digitatum, respectively. Doses of 1–4% induced phytotoxicity in the form of a discolored ring surrounding the wound on the epidermis of the fruit; this phytotoxicity enlarged as the concentration of SMB increased. The phytotoxic features were similar on apples and oranges. The methodological procedure made it possible to carry out a quantitative assessment of SMB phytotoxicity. This method is proposed as an easy-to-use technique for quantitatively estimating the phytotoxicity of antifungal compounds on post-harvest fruit. Full article

This study investigated the inhibitory activity of organic solutions containing 5, 10, 15, 20 and 30% (w/v) sodium chloride and citric acid solution and 15:10, 15:15, 15:20 and 15:30% (w/v) sodium chloride (NaCl) combined with citric acid (CA) solution (salt/acid solution) for 10 min against microorganisms isolated from trimmed young coconut: Bacillus cereus, B. subtilis, Staphylococcus aureus, S. epidermidis, Enterobacter aerogenes, Serratia marcescens, Candida tropicalis, Lodderromyces elongisporus, Aspergillus aculeatus and Penicillium citrinum. Commercial antimicrobial agents such as potassium metabisulfite and sodium hypochlorite (NaOCl) were used as the controls. Results showed that 30% (w/v) NaCl solution displayed antimicrobial properties against all microorganisms, with s reduction range of 0.00–1.49 log CFU/mL. Treatment of 30% (w/v) CA solution inhibited all microorganisms in the reduction range of 1.50–8.43 log CFU/mL, while 15:20% (w/v) salt/acid solution was the minimum concentration that showed a similar antimicrobial effect with NaOCl and strong antimicrobial effect against Gram-negative bacteria. The mode of action of this solution against selected strains including B. cereus, E. aerogenes and C. tropicalis was also determined by scanning electron microscopy and transmission electron microscopy. B. cereus and E. aerogenes revealed degradation and detachment of the outer layer of the cell wall and cytoplasm membrane, while cytoplasmic inclusion in treated C. tropicalis cells changed to larger vacuoles and rough cell walls. The results suggested that a 15:20% (w/v) salt/acid solution could be used as an alternative antimicrobial agent to eliminate microorganisms on fresh produce. Full article

The study of new materials for radiation dosimetry is important to improve the present state of the art and to help in cases of accidents for retrospective dosimetry. Sulfites are compounds that contain a sulfur ion, widely used in the food industry. Due to the significant application of these compounds, sulfites are interesting candidates for accidental dosimetry, as fortuitous radiation detectors. The presence of the SO₃⁻ anion enables its detection by electron spin resonance (ESR) spectroscopy. The Dose–Response behavior, signal stability and other spectral features were investigated for sodium sulfite, sodium bisulfite, sodium metabisulfite and potassium metabisulfite, all in crystalline forms. The ESR spectrum of salts presented stability and proportional response with dose, presenting potential for dosimetry applications. Full article

The food industry is not the only sphere of human activity where inorganic food additives are globally used. In certain concentrations, they are safe for people and agricultural animals. Nonetheless, they impose a negative impact on other classes of living organisms. Therefore, our objective was to determinine the influence of some inorganic food additives (alkalis, acids, salts) on the vitality of nematode larvae that parasitize agricultural animals: Strongyloides papillosus, Haemonchus contortus and Muellerius capillaris. We studied the effects of sodium hydroxide, potassium hydroxide, boric acid, phosphoric acid, potassium chloride, calcium chloride, sodium nitrite, potassium nitrite, sodium nitrate, potassium nitrate, ammonium bicarbonate, sodium bisulfite, sodium bisulfate, sodium sulfate, potassium sulfate, calcium sulfate, sodium thiosulfate, sodium metabisulfite, potassium metabisulfite, copper sulfate pentahydrate, tetrasodium pyrophosphate, sodium triphosphate, sodium borate decahydrate and talc. In in vitro experiments, the strongest effects were produced by alkalis sodium hydroxide and potassium hydroxide. In 24 h, 1% solutions of those substances killed 69% of larvae of S. papillosus, H. contortus and M. capillaris of various development stages. Sodium sulfate was effective against all stages of larvae of S. papillosus, and also against first-age M. capillaris. Nematocidal properties only against all stages of S. papillosus were exerted by copper sulfate pentahydrate. Non-invasive stages of S. papillosus nematodes were affected only by phosphoric acid, ammonium bicarbonate, calcium chloride, sodium nitrite, calcium sulfate, potassium metabisulfite, tetrasodium pyrophosphate, sodium triphosphate and the same stages of M. capillaris—by phosphoric acid, sodium bisulfite and potassium nitrite. Full article

This work aims to synthesize graft copolymers of chitosan and N-vinylimidazole (VI) with different compositions to be used as matrices for the immobilization of cysteine proteases—bromelain, ficin, and papain. The copolymers are synthesized by free radical solution copolymerization with a potassium persulfate-sodium metabisulfite blend initiator. The copolymers have a relatively high frequency of grafting and yields. All the synthesized graft copolymers are water-soluble, and their solutions are characterized by DLS and laser Doppler microelectrophoresis. The copolymers are self-assembled in aqueous solutions, and they have a cationic nature and pH-sensitivity correlating to the VI content. The FTIR data demonstrate that synthesized graft copolymers conjugate cysteine proteases. The synthesized copolymer adsorbs more enzyme macromolecules compared to non-modified chitosan with the same molecular weight. The proteolytic activity of the immobilized enzymes is increased up to 100% compared to native ones. The immobilized ficin retains up to 97% of the initial activity after a one-day incubation, the immobilized bromelain retains 69% of activity after a 3-day incubation, and the immobilized papain retains 57% of the initial activity after a 7-day incubation. Therefore, the synthesized copolymers can be used as matrices for the immobilization of bromelain, ficin, and papain. Full article

The sulfur-containing salts, classified as food additives, sodium metabisulfite (SMBS), potassium metabisulfite (PMBS), aluminum sulfate (AlS), and aluminum potassium sulfate (AlPS), were evaluated for their activity against Monilinia fructicola, Rhizopus stolonifer, and Geotrichum candidum, the most economically important fungal pathogens causing postharvest disease of stone fruit. In in vitro tests with potato dextrose agar (PDA) Petri dishes amended with different concentrations of the salts (0, 10, 20, 30, 50, and 100 mM), SMBS and PMBS at all concentrations, AlS above 20 mM, and AlPS above 30 mM, completely inhibited the mycelial growth of the three fungi after incubation at 25 °C for up to 10 days. In in vivo primary screenings with artificially inoculated nectarines, aqueous solutions of the four salts reduced the incidence and severity of brown rot (BR) at concentrations of 10 and 50 mM, whereas only AlS and AlPS reduced Rhizopus rot (RR), and none of the salts was effective against sour rot (SR). Solutions at 100 mM were phytotoxic and injured the fruit peel. In small-scale trials, 1 min dip treatments at 20 °C in SMBS or PMBS at 10 mM significantly reduced the incidence and severity of BR after incubation at 20 °C for up to 8 days. Conversely, dips in AlS and AlPS reduced neither BR nor RR. Results highlight the potential of SMBS and PMBS as new nonpolluting tools for the integrated control of BR, but not RR and SR, on stone fruit. Full article

The 21st century has brought along many changes in how consumers look at food and perceive their diets. There is an increasing awareness towards what goes into manufacturing these foods, with an important concern being drawn towards food additives. While it is known that additives are needed to preserve or change attributes of food, it is also widely understood that consumers prefer natural additives to artificial ones, and thus, the industry is looking for alternatives from plant sources. The extraction of five different plants (oregano (Origanum vulgare L.), rosemary (Rosmarinus officinalis L.), salvia (Salvia officinalis L.), lemon balm (Melissa officinalis L.), and basil (Ocimum basilicum L.)) was optimized for three extraction types, namely decoction, infusion, and cold hydroethanolic (80:20) ultrasound-assisted extraction. This optimization was carried out through a screening analysis to find the most important factors, using Design Expert, pending the analysis of phenolic compounds through HPLC-DAD-ESI/MS. The optimized variables used were temperature, time of extraction, and potency (ultrasound). The extraction with the highest phenolic content for each plant was then selected and screened for its antibacterial and antifungal activity, relying on the microdilution method against foodborne pathogens. The bacterial strains used were Staphylococcus aureus, Bacillus cereus, Listeria monocytogenes, Escherichia coli, Salmonella typhimurium and Enterobacter cloacae, while the fungal strains were Aspergillus fumigatus, Aspergillus niger, Aspergillus versicolor, Penicillium funiculosum, Trichoderma viride, and Penicillium verrucosum var. cyclopium. Two synthetic and widely used preservatives, namely sodium benzoate (E211) and potassium metabisulfite (E224), were also screened against these contaminants to confirm the sensitivity of the microorganisms to these known artificial preservatives. Overall, the plant extracts showed a high inhibition of fungi, with all extracts showing lower minimum inhibition concentrations than both the synthetic preservatives, except for P. viridae, where E224 showed the same inhibition capacity. Regarding the antibacterial activity, the bacteria most sensitive to the extracts was B. cereus, for which all the extracts showed the same activity as E224. Lemon balm was the stronger extract, showing the same inhibition as E221 against B. cereus and E. cloacae. Overall, this work proves that plant extracts obtained though “green” and low-cost technologies can be alternatives to artificial food additives, due to showing the same, or, in some cases, better antimicrobial activity. Furthermore, a mixture of these extracts can result in synergistic effects and improve the antimicrobial activities. The next step of this work, which is ongoing, will focus on the determination of the efficacy of these extracts and their incorporation in muffins. Full article

Sulfur dioxide (SO₂) is important in the winemaking process as it aids in preventing microbial growth and the oxidation of wine. These processes and others consume the SO₂ over time, resulting in wines with little SO₂ protection. Furthermore, SO₂ and sulfiting agents are known to be allergens to many individuals and for that reason their levels need to be monitored and regulated in final wine products. Many of the current techniques for monitoring SO₂ in wine require the SO₂ to be separated from the wine prior to analysis. This investigation demonstrates a technique capable of measuring free sulfite concentrations in low volume liquid samples in white wine. This approach adapts a known colorimetric reaction to a suspended core optical fiber sensing platform, and exploits the interaction between guided light located within the fiber voids and a mixture of the wine sample and a colorimetric analyte. We have shown that this technique enables measurements to be made without dilution of the wine samples, thus paving the way towards real time in situ wine monitoring. Full article