Tooth whitening effects on dental enamel, oxidation or reduction? Comparison of physicochemical alterations in bovine enamel using Synchrotron-based Micro-FTIR.

OBJECTIVES: To compare the side effects of typical whitening treatments (by means of oxidation) compared to the new treatment developed by the authors through reduction. The aim is to provide information about the chemical interactions of the encapsulated reductant agent (metabisulfite, MBS) with the enamel structure compared with carbamide peroxide (CP) and to study their penetration in the hydroxyapatite (HAP) and the changes produced in the mineral and its hardness. METHODS: Chemical imaging is performed by synchrotron-based micro Fourier transformed infrared spectroscopy (SR-µFTIR). Continuous Stiffness Measurements (CSM) were used to determine the depth reached by the treatments in order to delimitate the area of study. RESULTS: The SR-µFTIR studies showed that MBS treatments softened the first 10 µm of enamel, as happens in the initial stages of tooth decay. Principal component analysis (PCA) showed that the main differences between treatments were found in the intensity of the ν3 PO43- peak related to tooth demineralization. CP and MBS promoted different changes in the HAP mineral, observed as opposite shifts of the peak: CP shortened the P-O bond while MBS seemed to elongate it. Moreover, MBS promoted the loss of carbonates while CP did not, which is probably related to the solution's pH. When comparing MBS and MBS Liposomes, it was observed how liposomes favoured the diffusion of MBS to inner layers, since the effects of MBS were observed in deeper enamel. Thus, the encapsulated MBS whitening effect is highly improved in terms of time when compared to MBS alone or CP. SIGNIFICANCE: The obtained results indicated that using oxidizing (CP) or reducing (MBS) treatments, promote different HAP mineral changes, and that liposomes favour the diffusion of MBS into the enamel. It is the first time that synchrotron light is used to map the bovine incisor's enamel chemically, and to determine the effect of a whitening treatment in terms of chemical HAP modifications, and the extent in deep of these effects.

Effects of deoxynivalenol and sodium meta-bisulphite on nutrient digestibility in growing pigs.

Deoxynivalenol (DON), a mycotoxin synthesised by the Fusarium, is known to affect the growth of pigs. This effect can be attenuated with sodium meta-bisulphite (SBS). The aim of this study was to evaluate the effect of SBS with antioxidant blend on nutrient digestibility in pigs fed a diet contaminated naturally with DON. Six crossbred castrated pigs fitted surgically with single-T cannulas in the distal ileum received one of four barley-corn-soybean diets with or without SBS. After 8 d of feeding, faeces and ileal digesta were collected for 2 d. Apparent ileal digestibility (AID) of the dry matter (DM), energy, nutrients and DON, and apparent total tract digestibility (ATTD) of DM, acid detergent fibre (ADF), neutral detergent fibre (NDF), energy and DON were evaluated. The AID of phosphorus, calcium and some amino acids was increased (p < 0.05) in the DON diets whereas the ATTD of DM and energy tended to decrease (p = 0.064 and p = 0.071). SBS reduced the AID of DM, energy, ADF, ether extract, phosphorus and DON (p < 0.05) but had no effect on the ATTD of DM, energy, fibre or DON. These results show that DON improved the AID of some nutrients but tended to reduce the ATTD of energy, which could explain, although anorexia is the main effect of DON on live weight gain, the reported negative effect of DON on pig growth. Finally, SBS with antioxidant blend had reduced AID of some nutrients and intestinal absorption of DON.

Protective effect of vitamin E and vitamin C alone and in combination on testicular damage induced by sodium metabisulphite in rats: A stereological study.

The existing investigation was directed to consider the protective role of vitamin C and E alone and in combination on sodium metabisulphite-induced damage on testicular. Experimental animals were received sodium metabisulphite (520 mg/kg) alone and in combination with vitamin E (100 mg/kg), vitamin C (100 mg/kg) and vitamin E + C, while the control groups received 0.9% saline solution and olive oil (the solvent of the vitamin E). Finally, the changes in the testis histology were examined stereologically. Lipid peroxidation was assessed through the measurement of malondialdehyde (MDA) levels in testis tissues. Also, serum testosterone concentrations were measured. The results indicated that 80%-90% (spermatogonia A and B, spermatocyte and Leydig) and 40% of the Sertoli cells were missed in the rats that received sodium metabisulphite, respectively, compared with the controls. The co-supplementation of vitamin E with vitamin C significantly decreased MDA (p = 0.006) and increased testosterone (p = 0.001) concentrations in the rats received SMB which were as much as control and olive groups. Co-supplementation of vitamin E and vitamin C due to their synergistic effects could be an appropriate strategy in preventing testicular from sodium metabisulphite-induced damage.

Hydrometallurgical recycling of lithium-ion batteries by reductive leaching with sodium metabisulphite.

The hydrometallurgical extraction of metals from spent lithium-ion batteries (LIBs) was investigated. LIBs were first dismantled and a fraction rich in the active material was obtained by physical separation, containing 95% of the initial electrode, 2% of the initial steel and 22% of plastic materials. Several reducers were tested to improve metals dissolution in the leaching step using sulphuric acid. Sodium metabisulphite led to the best results and was studied in more detail. The best concentration of Na2S2O5 was 0.1 M. The metals dissolution increased with acid concentration, however, concentrations higher than 1.25 M are unnecessary. Best results were reached using a stirring speed of 400 min-1. The metals leaching efficiency from the active material (Li, Mn, Ni, Co) increased with the temperature and was above 80% for temperatures higher than 60 °C. The dissolution of metals also rose with the increase in the liquid/solid ratio (L/S), however, extractions above 85% can be reached at L/S as lower as 4.5 L/kg, which is favourable for further purification and recovery operations. About 90% of metals extraction can be achieved after only 0.5 h of leaching. Sodium metabisulphite can be an alternative reducer to increase the leaching of Li, Mn, Co, and Ni from spent LIBs.

Gastric mucosal irritation following oral exposure to sodium metabisulphite: A reproducible effect?

Sulphiting agents, such as sodium metabisulphite (SM), are used in food as bleaching agents and to prevent browning reactions. A 1972 repeat dose study in rats found that dietary sulphites caused irritation of the stomach with inflammation, hyperplasia and bleeding. We conducted a 7-day dietary study in rats to confirm that stomach lesions were the most sensitive toxicological endpoint. Rat feed was prepared daily with 0%, 0.25%, 0.5%, 1% or 4% (w/w) SM. Parameters included clinical signs, feed and water intake, bodyweight gain, haematology, serum protein chemistry, necropsy findings and gastrointestinal histopathology. There were no treatment-related clinical signs or gastrointestinal lesions. Mean bodyweight gain was markedly decreased in the 4% (w/w) SM group although feed consumption was marginally depressed. Slightly lower mean values for RBC, Hb, Hct, total WBC and lymphocyte count were observed in the 4% SM group with no evidence of compensatory haematopoiesis. The gastric lesions in rats observed in a 1972 study of dietary SM for 10-56 days could not be replicated. These findings create uncertainty around the most relevant toxicological endpoint to establish a suitable health based guidance value, which can only be overcome if a robust long-term dietary study is undertaken.

Susceptibility of Clostridium difficile to the food preservatives sodium nitrite, sodium nitrate and sodium metabisulphite.

Clostridium difficile is an important enteric pathogen of humans and food animals. Recently it has been isolated from retail foods with prevalences up to 42%, prompting concern that contaminated foods may be one of the reasons for increased community-acquired C. difficile infection (CA-CDI). A number of studies have examined the prevalence of C. difficile in raw meats and fresh vegetables; however, fewer studies have examined the prevalence of C. difficile in ready-to-eat meat. The aim of this study was to investigate the in vitro susceptibility of 11 C. difficile isolates of food animal and retail food origins to food preservatives commonly used in ready-to-eat meats. The broth microdilution method was used to determine the minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) for sodium nitrite, sodium nitrate and sodium metabisulphite against C. difficile. Checkerboard assays were used to investigate the combined effect of sodium nitrite and sodium nitrate, commonly used in combination in meats. Modal MIC values for sodium nitrite, sodium nitrate and sodium metabisulphite were 250 µg/ml, >4000 µg/ml and 1000 µg/ml, respectively. No bactericidal activity was observed for all three food preservatives. The checkerboard assays showed indifferent interaction between sodium nitrite and sodium nitrate. This study demonstrated that C. difficile can survive in the presence of food preservatives at concentrations higher than the current maximum permitted levels allowed in ready-to-eat meats. The possibility of retail ready-to-eat meats contaminated with C. difficile acting as a source of CDI needs to be investigated.

Reducing agent and exogenous protease additions, individually and in combination, to wheat- and sorghum-based diets interactively influence parameters of nutrient utilisation and digestive dynamics in broiler chickens.

The objective of the study was to investigate the possibility that tandem inclusions of a reducing agent and a protease may advantage chicken-meat production and to ascertain if the established benefits of including sodium metabisulphite in sorghum-based diets extend to wheat-based diets. The study comprised a 2 × 2 × 2 factorial array of treatments in which either nutritionally iso-nitrogenous and iso-energetic wheat- or sorghum-based diets, without and with sodium metabisulphite (2.75 g/kg), without and with protease (1,000 units/kg) were offered to broiler chickens from 7 to 28 days post-hatch. The effects of dietary treatments on growth performance, nutrient utilisation, protein (N) and starch digestibility coefficients and digestive dynamics were determined. A preliminary investigation into the effects of two treatments on concentrations of free amino acids and glucose in the portal circulation was conducted. There was significant feed grain by sodium metabisulphite interactions (P = 0.03 to 0.005) for parameters of nutrient utilisation (AME, ME:GE ratios, N retention, AMEn). For example, sodium metabisulphite inclusions in sorghum-based diets enhanced AME by 0.18 MJ (12.47 versus 12.29 MJ/kg) but depressed AME by 0.43 MJ (11.88 versus 12.31 MJ/kg) in wheat-based diets. There was a linear relationship between starch:protein disappearance rate ratios in the distal ileum with weight gain (r = -0.484; P = 0.0012) indicating that condensed ratios (or absorption of more protein relative to starch) advantaged growth performance. Concentrations of free amino acids in the portal circulation or the post-enteral availability of certain amino acids, including the branched-chain amino acids, methionine, phenylalanine and threonine, were significantly correlated to FCR. For example, threonine concentrations were negatively correlated to FCR (r = -0.773; P = 0.005). Finally, tandem inclusions of sodium metabisulphite and protease in sorghum-based diets may hold merit but it appears that the established 'energy sparing' effects of sodium metabisulphite inclusions in sorghum-based diets are not duplicated in wheat-based diets.

Modelling the influence of temperature, water activity and sodium metabisulphite on the growth and OTA production of Aspergillus carbonarius isolated from Greek wine grapes.

The purpose of the present study was to develop a modelling approach to quantify the effect of temperature (15-38 °C), a(w) (0.88-0.98) and sodium metabisulphite (NaMBS) concentration (0-200 mg L(-1)) on the growth and OTA production of Aspergillus carbonarius on a Grape Juice based Medium (GJM). Growth responses of the fungus were recorded over time in terms of colony diameter changes, and fitted to the primary model of Baranyi and the estimated maximum growth rates (µ(max)) and lag phases (λ) were subsequently modelled as a function of temperature, a(w) and NaMBS concentration using the cardinal values model with inflection (CMI). Moreover, OTA production was measured during fungal growth and modelled as a function of the same parameters through a quadratic polynomial model. Results showed that NaMBS increased the lag phase of A. carbonarius, particularly at 38 °C/0.98 a(w) and 38 °C/0.96 a(w), as well as at lower a(w) levels regardless of temperature. In the lowest NaMBS concentration (50 mg L(-1)) there was no inhibitory effect, while at higher concentrations (100 and 150 mg L(-1)) fungal growth was delayed. No growth was observed at 200 mg L(-1) of NaMBS irrespective of temperature and a(w) levels. The optimum values for growth were found in the range 30-35 °C and 0.96 a(w), while for OTA production at 20 °C and 0.98 a(w). The developed models were subjected to internal and external validation and presented satisfactory performance as inferred by graphical plots and statistical indices (bias and accuracy factors). The present study will complement the findings on the ecophysiology of A. carbonarius using NaMBS as an inhibitory agent.

Effect of baking improvers on the quality of whole cassava biscuits.

Improving agents such as ascorbic acid, sodium metabisulphite, sorbic acid and soyflour were used in the production of whole cassava biscuits. Cassava flour and small amount of soyflour were produced. Bulk density, water binding capacity and amylograph viscosity of cassava flour were determined. Mixing and dough extrusion time were recorded for each sample of biscuit dough developed with addition of improvers. Length, width and thickness of cut-out dough were measured before and after baking to evaluate biscuits flow. Proximate and sensory analysis of the biscuits samples was also determined. The result showed that, there was a slight decrease in mixing time, extrusion time, length and width of the biscuits samples prepared with improvers. However, there was a considerable increase in biscuits thickness. Amylograph result showed an improvement in flour stability and low retrogadation tendency, most especially flour with inclusion of ascorbic acid. Crude protein and fat increased with sample contained soyflour. Sensory evaluation result indicated no significant difference among the samples except the texture of the biscuits.

Assessment of the abiotic and biotic effects of sodium metabisulphite pulses discharged from desalination plant chemical treatments on seagrass (Cymodocea nodosa) habitats in the Canary Islands.

Reverse osmosis membranes at many desalination plants are disinfected by periodic shock treatments with sodium metabisulphite, which have potentially toxic effects to the environment for marine life, although no empirical and experimental evidence for this is yet available. The aim of this study was to characterise for the first time, the physico-chemical modification of the marine environment and its biological effects, caused by hypersaline plumes during these membrane cleaning treatments. The case study was the Maspalomas II desalination plant, located in the south of Gran Canaria (Canary Islands, Spain). Toxicity bioassays were performed on marine species characteristic for the infralittoral soft bottoms influenced by the brine plume (Synodus synodus and Cymodocea nodosa), and revealed a high sensitivity to short-term exposure to low sodium metabisulphite concentrations. The corrective measure of incorporating a diffusion system with Venturi Eductors reduced nearly all the areas of influence, virtually eliminating the impact of the disinfectant.

Análise sensorial do camarão santana ou vermelho, Pleoticus muelleri (malacostraca: aristeidae), refrigerado e irradiado, Pleoticus muelleri (malacostraca: aristeidae), refrigerado e irradiado) / Análisis sensorial del camarón santana o rojo, Pleoticus muelleri (Malacostraca: aristeidae), Refrigerado e irradiado / Sensorial analysis of Pleoticus Muelleri (malacostraca: aristeidae) red shrimp submitted to refrigeration and irradiation

O tempo de conservação do camarão é muito curto, e sua estocagem é difícil. O tratamento do metabissulfito de sódio e a irradiação foi realizado com o objetivo de prolongar a vida útil do produto. O metabissulfito de sódio é um antioxidante usado para evitar o aparecimento de melanose no camarão, logo após a pesca. O principal objetivo do trabalho foi avaliar o efeito da radiação gama em camarões (Pleoticus muelleri) refrigerados com e sem adição de metabissulfito, por meio de características sensoriais (cor, odor e aspecto geral) e o aparecimento de ?black spot?. Foram investigados 4 grupos de amostras: amostra controle (0 kGy), amostra adicionada de 2% de metabissulfito de sódio, amostra irradiada a 1,5 kGy, amostra irradiada com 1,5 kGy e adicionada 1,25% de metabissulfito de sódio. Concluiu-se que a irradiação na dose estudada não altera o produto quanto a sua qualidade sensorial comparado a amostra controle. O tratamento em solução de metabissulfito de sódio a 2% apresenta melhor resultado do que as demais amostras tanto na formação de ?black spot? quanto sensorialmente.

Shrimp conservation time is very short, making its storage difficult. Aiming to extend its useful life, a treatment with sodium metabisulphite and irradiation was used. Sodium metabisulphite is an antioxidant used to prevent the occurrence of melanosis in refrigerated shrimp right after fishing. The main goal of this study is to evaluate the effect of gamma radiation on shrimp (Pleoticus muelleri), with and without the addition of sodium metabisulphite, regarding its sensorial characteristics (color, odor and general appearance) and the appearing of ?black spots?. Four samples were investigated, divided in 4 groups: control samples (0 kGy), samples with sodium metabisulphite 2%, samples irradiated at 1.5 kGy without sodium metabisulphite, and samples irradiated at 1,5 kGy with sodium metabisulphite 1.25%. It was concluded that irradiation at the studied dose does not alter the product, regarding its sensorial quality, when compared to the control sample. The treatment with sodium metabisulphite solution at 2% shows a better result than the other samples for the formation of ?black spot? as well as for the sensorial aspects.

El tiempo de conservación del camarón es muy corto, y su almacenamiento es difícil. El tratamiento con meta bisulfito de sodio y la irradiación se realizó con el objetivo de prolongar la vida útil del producto. El meta bisulfito de sodio es un antioxidante usado para evitar la aparición de melanosis en el camarón, luego después de la pesca. El principal objetivo del estudio fue evaluar el efecto de la radiación gamma en camarones (Pleoticus muelleri) refrigerados con y sin adicción de meta bisulfito, por medio de características sensoriales (color, olor y aspecto general) y la aparición de ?Black spot?. Se investigó 4 grupos de muestras: muestra control (0 kGy), muestra adicionada de 2% de meta bisulfito de sodio, muestra irradiada a 1,5 kGy y adicionada 1,25% de meta bisulfito de sodio. Se concluyó que la irradiación en la dosis estudiada no altera el producto cuanto a su calidad sensorial, comparado a la muestra control. El tratamiento en solución de meta bisulfito de sodio a 2% presenta mejor resultado que las demás muestras, tanto en la formación de ?Black spot? como sensorialmente.

Efeito in vitro de concentrações de metabisulfito de sódio, benzoato de sódio e sorbato de potássio sobre fungos termorresistentes / In vitro effect of concentrations of sodium metabisulphite, sodium benzoate and potassium sorbate on heat-resistant fungi

Os fungos termorresistentes dos gêneros Byssochlamys, Neosartorya e Talaromyces representam grave problema para a indústria processadora de alimentos, especialmente de frutas e hortaliças, em virtude da ocorrência de ascosporos extremamente resistentes e/ou de micotoxinas termo estáveis. Com o propósito de fornecer subsídios quanto ao uso de quantidades mais racionais de conservantes pela indústria de alimentos e, portanto, tornar seu consumo menos danoso à população, o presente estudo determinou in vitro a concentração mínima de metabissulfito de sódio, benzoato de sódio e sorbato de potássio necessária e suficiente para inibir o crescimento micelial e a germinação de ascósporos de B. fulva, N. fischeri e T.flavus em meio de cultivo acidificado (pH 3,5). Foi demonstrado que metabissulfito de sódio em baixas concentrações é tão eficiente na inibição dos fungos mencionados quanto aos demais conservantes em altas concentrações. Por comparação com os procedimentos utilizados pelas indústrias de alimentos, é possível inferir que estas podem reformular o uso de conservantes, considerando-se o tipo de matéria-prima, a temperatura de processamento, a combinação e concentração efetivamente necessária de aditivos, bem como os efeitos tóxicos desses compostos para a saúde humana.