Cysteine, sodium metabisulfite, and glutathione enhance crosslinking between proteins during high moisture meat analog extrusion processing and may improve the fibrousness of the products.

BACKGROUND: High moisture meat analog (HMMA) products processed using extrusion have become increasingly popular in the last few years. Because the formation of disulfide bonds is believed to play a critical role in the texturization mechanism, this study aimed to understand how chemical compounds capable of reducing disulfide bonds, specifically cysteine, sodium metabisulfite, and glutathione, affect the texture and the chemical interactions between the proteins. METHOD: Wheat protein blended with cysteine, sodium metabisulfite, or glutathione at levels of 0, 0.5, 1.0, 2.5, 5.0, and 7.5 g kg-1 was extruded at three different temperatures (115, 140, and 165 °C) using a co-rotating twin-screw extruder. The feed rate (85 g min-1), the moisture content (600 g kg-1), and the screw speed (300 rpm) were kept constant. Unextruded and extruded material was subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoresis, polymeric protein fractionation, and sulfhydryl group/disulfide bond analysis. Extruded samples were further analyzed for their hardness and their anisotropic index. RESULTS: The inclusion of reductants significantly affected the structure of the obtained extrudates. Although reducing agents had a relatively small impact on the total amount of disulfide bonds, their action significantly enhanced crosslinking between the proteins. At select conditions, samples with high fibrousness were specifically obtained when cysteine or sodium metabisulfite was included at levels of 5.0 g kg-1. DISCUSSION: In the presence of reducing agents, it is believed that disulfide bonds are split earlier during the process without binding to them, giving the protein strands more time to unravel and align, leading to a better flow behavior and more fibrous products. © 2024 Society of Chemical Industry.

Contact sensitisation in oral lichen planus: An Australian perspective.

BACKGROUND: The role of contact sensitisation in the pathogenesis of oral lichen planus (OLP) has not been clearly defined. OBJECTIVE: We aimed to evaluate relevant contact sensitisers in OLP. METHODS: A retrospective study was conducted on OLP patients who underwent patch testing from 1 January 2006 to 31 December 2020 at an Australian tertiary dermatology institution, compared to cheilitis patients patch tested over the same time period. RESULTS: Ninety-six OLP patients and 152 cheilitis patients were patch tested during the 15-year period. Seventy-one (73.9%) OLP patients and 100 (65.8%) cheilitis patients recorded one or more relevant reactions. Forty-three (44.8%), 22 (22.9%), 21 (21.9%) and 17 (17.7%) OLP patients had relevant reactions to mercury-related chemicals, amalgam, spearmint and carvone, respectively, compared to 6 (3.9%), 3 (2.0%), 4 (2.6%) and 0 (0%) cheilitis patients, respectively (p-value <0.001 each). Four (4.2%) OLP patients had relevant positive reactions to sodium metabisulfite, compared to none in the cheilitis group (p-value 0.021). CONCLUSION: While dental amalgam is used less frequently these days, we report that mercury (found in amalgam) and additionally spearmint and carvone are relevant sensitisers in OLP in Australia. Sodium metabisulfite may also be a relevant sensitiser in OLP, which has not previously been reported.

European patch test results with audit allergens as candidates for inclusion in the European Baseline Series, 2019/20: Joint results of the ESSCAA and the EBSB working groups of the ESCD, and the GEIDACC.

BACKGROUND: In 2019, a number of allergens (haptens), henceforth, "the audit allergens," were considered as potential additions to the European Baseline Series (EBS), namely, sodium metabisulfite, 2-bromo-2-nitropropane-1,3-diol, diazolidinyl urea, imidazolidinyl urea, Compositae mix II (2.5% or 5% pet), linalool hydroperoxides (lin-OOH), limonene hydroperoxides (lim-OOH), benzisothiazolinone (BIT), octylisothiazolinone (OIT), decyl glucoside, and lauryl glucoside; Evernia furfuracea (tree moss), was additionally tested by some departments as well. OBJECTIVES: To collect further data on patch test reactivity and clinical relevance of the audit allergens in consecutive patients across Europe. METHODS: Patch test data covering the audit allergens in 2019 and 2020 were collected by those departments of the European Surveillance System on Contact Allergies testing these, as well as further collaborators from the EBS working group of the European Society of Contact Dermatitis (ESCD), and the Spanish Grupo Español de Investigación en Dermatitis de Contacto y Alergia Cutánea. As patch test outcome, reactions between day (D) 3 and D5 were considered. RESULTS: Altogether n = 12 403 patients were tested with any of the audit allergen. Positive reactions were most common to lin-OOH 1% pet. (8.74% [95%CI: 8.14-9.37%]), followed by lin-OOH 0.5% pet., and lim-OOH 0.3% pet (5.41% [95% CI: 4.95-5.89%]). Beyond these terpene hydroperoxides, BIT 0.1% pet. was the second most common allergen with 4.72% (95% CI: 4.2-5.28%), followed by sodium metabisulfite 1% pet. (3.75% [95%CI: 3.32-4.23%]) and Compositae mix 5% pet. (2.31% [95% CI: 1.84-2.87%]). For some allergens, clinical relevance was frequently difficult to ascertain. CONCLUSIONS: Despite many positive patch test reactions, it remains controversial whether lin- and lim-OOH should be tested routinely, while at least the two preservatives BIT and sodium metabisulfite appear suitable. The present results are a basis for further discussion and ultimately decision on their implementation into routine testing among the ESCD members.

Trends in preservative allergy: Benzisothiazolinone emerges from the pack.

BACKGROUND: Preservatives are used widely in cosmetic, household, and industrial products to prevent microbial growth and spoiling of the products. There has been a recent epidemic of contact allergy to methylisothiazolinone (MI). OBJECTIVES: To establish emerging trends in preservative contact allergy as MI is replaced. METHODS: We performed a retrospective study on consecutively patch-tested patients at our center from January 2011 to December 2019. RESULTS: A total of 7846 consecutively patch-tested patients were included who were patch tested between January 2011 and December 2019. The prevalence of allergy to MI fell from a peak of 9.39% in 2013 to 1.98% in 2019. MI/methylchloroisothiazolinone (MCI) followed a similar trend, with a peak prevalence of 7.85% in 2014 and falling to 1.39% in 2018. The prevalence of contact allergy to benzisothiazolinone (BIT) has increased steadily increased in 2014 from 0.26% (confidence interval [CI] 0.03-0.93) to 3.42% (CI 2.43-4.66) in 2019. CONCLUSIONS: Our data show a significant increase in the prevalence of contact allergy to BIT over the last 6 years, probably as a consequence of increased use in household products. It is essential to continue to look for emerging trends in contact allergy to enable prompt preventative measures to be taken.

Patch testing with sodium disulfite: North American Contact Dermatitis Group experience, 2017 to 2018.

BACKGROUND: Sodium disulfite (SD), also known as sodium metabisulfite, is an increasingly recognized cause of allergic contact dermatitis. OBJECTIVES: The objective of this work was to characterize individuals with positive patch test reactions to SD as well as analyse reaction strength, clinical relevance, and sources. METHODS: This is a retrospective analysis of patients patch tested with SD (1% petrolatum) by the North American Contact Dermatitis Group (NACDG), 2017 to 2018. RESULTS: Of 4885 patients patch tested with SD, 132 (2.7%) had a positive reaction. Common primary anatomic sites of dermatitis were face (28.8%), hands (20.5%), and a scattered/generalized distribution (13.6%). Compared with SD-negative patients, SD-positive patients were more likely male (odds ratio 2.81, 95% confidence interval 1.98-4.00) and/or over 40 years (odds ratio 1.95, 95% confidence interval 1.30-2.94). Reactions were most commonly + (50.4%) or ++ (34.1%); 65.2% were considered currently relevant. About 15.2% were definitively confirmed in sources, commonly personal care products (18.9%, especially hair dye), and drugs/medications/alcoholic beverages (9.1%). Only 2.3% of positive reactions were linked to occupation. CONCLUSIONS: Positive reactions to SD occurred in 2.7% of tested patients. Reactions were often clinically relevant and linked to personal care products and drugs/medications/alcoholic beverages.

Comparative antibacterial and antifungal activities of sulfur nanoparticles capped with chitosan.

The antimicrobial activity of sulfur nanoparticles (SNPs) was compared with elemental sulfur and sulfur-containing salts (sodium thiosulfate and sodium metabisulfite) against bacteria (Escherichia coli, Staphylococcus aureus) and fungi (Aspergillus flavus, Candida albicans) using the paper disc, broth microdilution, and time-kill assay methods. The results of the paper disc and MIC tests showed stronger antimicrobial activity of SNPs compared to the elemental sulfur and sulfur-containing salts. SNPs showed more potent activity against bacteria than fungi. Among the test microorganisms, E. coli (Gram-negative) was the most susceptible to SNPs, followed by S. aureus (Gram-positive), C. albicans (yeast), and A. flavus (mold). Scanning electron micrographs of microorganisms treated with SNPs showed different cell disruption patterns depending on the type of microorganisms.

Breaking the rules: tooth whitening by means of a reducing agent.

OBJECTIVES: It is widely accepted that current tooth whitening treatment effect is based on the oxidizing action of peroxides, even if the mechanism of action remains still unclear. Treatments are claimed to be safe, but several secondary effects have been described, since long application times and high concentrations are needed. A faster whitening ingredient which permits the use of lower concentrations and shorter application times could potentially overcome this problem. In this work, a different approach based on a reducing agent, sodium metabisulfite (MBS), is explored. MATERIALS AND METHODS: The reaction between tannic acid (TA) with carbamide peroxide (CP), MBS, and potassium persulfate (PS), as an oxidizing agent, was monitored for 48 hours by measuring its absorbance, comparing their different whitening effects. The reduction process between TA and MBS was confirmed by cyclic voltammetry. An in vitro test was used to observe if MBS whitens also stained teeth. RESULTS: It is shown that MBS bleaching effect is faster and higher than CP's effect over time. PS produced a darkening effect after the 3rd hour because of the strong absorbance of the oxidation metabolite. Cyclic voltammetry showed a progressive increase in the intensity of the TA anodic peak when MBS was present, demonstrating that a reduction is taking place. In vitro, MBS showed a faster whitening performance than CP, using lower concentrations. CONCLUSIONS: Using a TA solution as a staining model, it was possible to show that MBS has a visible bleaching effect through a reduction reaction, faster than CP, both in solution and in vitro. Low concentrations of MBS are effective in whitening. CLINICAL SIGNIFICANCE: This work shows MBS as a promising candidate to develop novel whitening treatments, which is acting by reducing mechanism instead of oxidation.

Fruit and vegetable discards preserved with sodium metabisulfite as a high-moisture ingredient in total mixed ration for ruminants: effect on in vitro ruminal fermentation and in vivo metabolism.

OBJECTIVE: Our recent series of laboratory- and large-scale experiments confirmed that under aerobic and anaerobic conditions, sodium metabisulfite (SMB) was effective in preserving nutrients and antioxidant capacity of highly perishable fruit and vegetable discards (FVD). Hence, the purpose of this study was to examine how partial inclusion of SMB-treated FVD in total mixed ration (TMR) influences in vitro ruminal fermentation, whole-tract digestibility, nitrogen metabolism, blood metabolites, and voluntary feed intake of sheep. METHODS: The FVD were mixed thoroughly with 6 g SMB/kg wet biomass and kept outdoors under aerobic conditions for 7 days. Four TMRs including four levels of SMB-treated FVD (as-fed basis) at 0%, 10%, 20%, and 30% (equaling to 0%, 1.9%, 3.8%, and 5.7% on dry matter basis, respectively), were prepared as replacement for corn grain. The ruminal fermentation metabolites were studied using an in vitro gas production test. Four mature male Corriedale sheep were assigned at random to the 4 diets for two separate sub-experiments; i) digestibility trial with four 21-d periods, and ii) voluntary feed intake trial with four 28-d periods. RESULTS: Inclusion of SMB-treated FVD in the TMR tended to quadratically increase partitioning factor. No effect was seen on total-tract digestibility of organic matter, ether extract, crude protein, and acid detergent fiber, except for neutral detergent fiber digestibility that tended to linearly increase with increasing SMB-treated FVD in the TMR. The progressive increase of FVD preserved with SMB in the diet had no effect on nitrogen metabolism. Treatment had no effect on serum antioxidant capacity and blood metabolites assayed. Voluntary feed intake was not impaired by inclusion of SMB-treated FVD in the TMR. CONCLUSION: It appears that FVD preserved with SMB can be safely incorporated into TMR as replacement of corn grain without impairment of nutrient metabolism and feed intake.

Multicomponent Reductive Cross-Coupling of an Inorganic Sulfur Dioxide Surrogate: Straightforward Construction of Diversely Functionalized Sulfones.

Conventionally, sulfones are prepared by oxidation of sulfides with strong oxidants. Now, a multicomponent reductive cross-coupling involving an inorganic salt (sodium metabisulfite) for the straightforward construction of sulfones is disclosed. Both intramolecular and intermolecular reductive cross-couplings were comprehensively explored, and diverse sulfones were accessible from the corresponding alkyl and aryl halides. Intramolecular cyclic sulfones were systematically obtained from five- to twelve-membered rings. Naturally occurring aliphatic systems, such as steroids, saccharides, and amino acids, were highly compatible with the SO2 -insertion reductive cross-coupling. Four clinically applied drug molecules, which include multiple heteroatoms and functional groups with active hydrogens, were successfully prepared via a late-stage SO2 insertion. Mechanistic studies show that alkyl radicals and sulfonyl radicals were both involved as intermediates in this transformation.

A proposal to create an extension to the European baseline series.

BACKGROUND: The current European baseline series consists of 30 allergens, and was last updated in 2015. OBJECTIVES: To use data from the European Surveillance System on Contact Allergies (ESSCA) to propose an extension to the European baseline series in response to changes in environmental exposures. METHODS: Data from departmental and national extensions to the baseline series, together with some temporary additions from departments contributing to the ESSCA, were collated during 2013-2014. RESULTS: In total, 31689 patients were patch tested in 46 European departments. Many departments and national groups already consider the current European baseline series to be a suboptimal screen, and use their own extensions to it. The haptens tested are heterogeneous, although there are some consistent themes. Potential haptens to include in an extension to the European baseline series comprise sodium metabisulfite, formaldehyde-releasing preservatives, additional markers of fragrance allergy, propolis, Compositae mix, and 2-hydroxyethyl methacrylate. CONCLUSION: In combination with other published work from the ESSCA, changes to the current European baseline series are proposed for discussion. As well as addition of the allergens listed above, it is suggested that primin and clioquinol should be deleted from the series, owing to reduced environmental exposure.

Preservation of fruit and vegetable discards with sodium metabisulfite.

Two series of experiments were performed to investigate the aerobic preservation of fruit and vegetable discards (FVD) using sodium metabisulfite (SMB). In Exp. 1, metabisulfite was applied at 0, 2, 4, 6, and 8 g/kg FVD for 0, 3, 6, 9, and 12 d. Metabisulfite treatment at 6 and 8 g/kg FVD was highly effective in controlling putrefaction and preserving the nutrient components for 6 and 9 d, respectively. In the pilot-scale experiment (Exp. 2), SMB was applied at 0 and 8 g/kg FVD in a 600-L bucket for 0, 6, and 9 d in an outdoor environment. The SMB treatment was highly effective in maintaining the integrity and freshness of FVD, suppressing microbial proliferation, and preserving the nutrient constituents. Under the conditions of this study, SMB effectively preserved FVD in an aerobic environment, enabling their more efficient long-term recycling through livestock feed or development of value-added products.

The effect of ingested sulfite on active avoidance in normal and sulfite oxidase-deficient aged rats.

The aim of this study was to investigate the possible toxic effects of sulfite on neurons by measuring active avoidance learning in normal and sulfite oxidase (SOX)-deficient aged rats. Twenty-four months of age Wistar rats were divided into four groups: control (C), sulfite-treated group (S), SOX-deficient group (D) and SOX-deficient + sulfite-treated group (DS). SOX deficiency was established by feeding rats with a low molybdenum (Mo) diet and adding 200 ppm tungsten (W) to their drinking water. Sulfite in the form of sodium metabisulfite (25 mg/kg) was given by gavage for six weeks. Active avoidance responses were determined by using an automated shuttle box. Hepatic SOX activity was measured to confirm SOX deficiency. The hippocampus was used for determining the activity of cyclooxygenase (COX) and caspase-3 enzymes and the level of prostaglandin E2 (PGE2) and nitrate/nitrite. SOX-deficient rats had an approximately 10-fold decrease in hepatic SOX activity compared with normal rats. Sulfite did not induce impairment of active avoidance learning in SOX-deficient rats and in normal rats compared with their control groups. Sulfite had no effect on the activity of COX and caspase-3 in the hippocampus. Treatment with sulfite did not significantly increase the level of PGE2 and nitrate/nitrite in the hippocampus.

Contact dermatitis in patients undergoing serial intravitreal injections.

BACKGROUND: Anti-vascular endothelial growth factor (VEGF) medication, injected intravitreally, is currently the standard of care in patients with different retinal pathologies. Since its introduction in 2006, an increasing number of patients have undergone this procedure in Ghent University Hospital. Strikingly, more patients were diagnosed with contact dermatitis caused by ophthalmic products used during intravitreal injection procedure. OBJECTIVES: To identify which of the substances used during intravitreal injection is most likely to cause contact dermatitis. PATIENTS/MATERIALS/METHODS: Sixteen patients who developed a burning and stinging sensation and swelling of the eyelids after intravitreal injection were tested. All patients were patch tested with the Belgian baseline series, as well as a cosmetic, a pharmaceutical and an ophthalmic series, including the different eye drops used during the intravitreal injection procedure. RESULTS: Fourteen of 16 patients reacted to at least one of the substances used during the injection procedure. Nine patients reacted to phenylephrine (56%), 5 to iso-Betadine(®) ophthalmic solution (31%), and 3 patients to sodium metabisulfite (16%). CONCLUSIONS: The most common causal allergen was phenylephrine, being positive in 56% of patients. Patients most likely become sensitized because of the high frequency of usage of phenylephrine during repeated intravitreal injections and follow-up consultations.

The effect of ingested sulfite on visual evoked potentials, lipid peroxidation, and antioxidant status of brain in normal and sulfite oxidase-deficient aged rats.

Sulfite, commonly used as a preservative in foods, beverages, and pharmaceuticals, is a very reactive and potentially toxic molecule which is detoxified by sulfite oxidase (SOX). Changes induced by aging may be exacerbated by exogenous chemicals like sulfite. The aim of this study was to investigate the effects of ingested sulfite on visual evoked potentials (VEPs) and brain antioxidant statuses by measuring superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) activities. Brain lipid oxidation status was also determined via thiobarbituric acid reactive substances (TBARS) in normal- and SOX-deficient aged rats. Rats do not mimic the sulfite responses seen in humans because of their relatively high SOX activity level. Therefore this study used SOX-deficient rats since they are more appropriate models for studying sulfite toxicity. Forty male Wistar rats aged 24 months were randomly assigned to four groups: control (C), sulfite (S), SOX-deficient (D) and SOX-deficient + sulfite (DS). SOX deficiency was established by feeding rats with low molybdenum (Mo) diet and adding 200 ppm tungsten (W) to their drinking water. Sulfite in the form of sodium metabisulfite (25 mg kg(-1) day(-1)) was given by gavage. Treatment continued for 6 weeks. At the end of the experimental period, flash VEPs were recorded. Hepatic SOX activity was measured to confirm SOX deficiency. SOX-deficient rats had an approximately 10-fold decrease in hepatic SOX activity compared with the normal rats. The activity of SOX in deficient rats was thus in the range of humans. There was no significant difference between control and treated groups in either latence or amplitude of VEP components. Brain SOD, CAT, and GPx activities and brain TBARS levels were similar in all experimental groups compared with the control group. Our results indicate that exogenous administration of sulfite does not affect VEP components and the antioxidant/oxidant status of aged rat brains.

The molecular mechanisms of sodium metabisulfite on the expression of K ATP and L-Ca2+ channels in rat hearts.

Sodium metabisulfite (SMB) is used as an antioxidant and antimicrobial agent in a variety of drugs and foods. However, there are few reported studies about its side effects. This study is to investigate the SMB effects on the expression of ATP-sensitive K(+) (KATP) and L-type calcium (L-Ca(2+)) channels in rat hearts. The results show that the mRNA and protein levels of the KATP channel subunits Kir6.2 and SUR2A were increased by SMB; on the contrary, SMB at 520 mg/kg significantly decreased the expression of the L-Ca(2+) channel subunits Cav1.2 and Cav1.3. This suggests that SMB can activate the expression of KATP channel by increasing the mRNA and protein levels of Kir6.2 and SUR2A, while it inhibits the expression of L-Ca(2+) channels by decreasing the mRNA and protein levels of Cav1.2 and Cav1.3 in rat hearts. Therefore, the molecular mechanism of the SMB effect on rat hearts might be related to the increased expression of KATP channels and the decreased expression of L-Ca(2+) channels.

Effect of sodium metabisulfite treatment and storage condition on metabolic profile of young coconut (Cocos nucifera L.).

Young coconuts (Cocos nucifera L.) used for export are trimmed to reduce their size and weight to lower transport costs. However, trimmed coconuts have a shorter shelf life due to microbial spoilage and surface discoloration caused by enzymatic browning. To minimize these effects, trimmed coconuts were dipped in an anti-browning agent, sodium metabisulfite (SMB), and stored under ambient conditions. However, there have been no reports on the effects of SMB treatment on metabolome changes in the flesh and water of young coconuts. Hence, this study investigated the metabolite changes in trimmed young coconuts after SMB treatment under different storage conditions using a gas chromatography (GC)/mass spectrometry (MS) metabolomic profiling approach. Tall young coconut samples were trimmed and treated with a 2% SMB solution for 5 min before storage at 25 °C or 4 °C for 2-4 weeks. Coconut flesh and water samples were collected after storage for 0, 2, and 4 weeks, and were subjected to GC-MS analysis. The results showed that the major metabolites affected by coconut deterioration were amino acids, sugars, and sugar alcohols. SMB treatment and/or refrigeration can help prevent metabolite changes in the flesh and water of young coconuts. In the future, improvements in storage conditions based on metabolite profiles should be explored.

Effectiveness of Several GRAS Salts against Fungal Rot of Fruit after Harvest and Assessment of the Phytotoxicity of Sodium Metabisufite in Treated Fruit.

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.