A rapid spectroscopic method to detect the fraudulent treatment of tuna fish with carbon monoxide

Effects of Different Phenolic Compounds on the Redox State of Myoglobin and Prevention of Discoloration, Lipid and Protein Oxidation of Refrigerated Longtail Tuna (Thunnus tonggol) Slices

Effects of different phenolic compounds on the redox state of myoglobin and their potential for preserving the color and chemical quality of refrigerated longtail tuna (Thunnus tonggol) slices were studied. Purified myoglobin from dark muscle (15.83 kDa) was prepared. Catechin, EGCG, quercetin, and hyperoside affected the absorption spectra and redox state of metmyoglobin (metMb) at 4 °C for up to 72 h differently. Reduction of metMb to oxymyoglobin (oxyMb) was notably observed for two flavonols (EGCG and quercetin) at 50 and 100 ppm. Based on the reducing ability of metMb, EGCG and quercetin were selected for further study. Longtail tuna slices were treated with EGCG and quercetin at 200 and 400 mg/kg. Color (a* and a*/b*), proportion of myoglobin content, and quality changes were monitored over 72 h at 4 °C. Tuna slices treated with 200 mg/kg EGCG showed better maintenance of oxyMb and color as well as lower lipid oxidation (PV and TBARS) and protein oxidation (carbonyl content) than the remaining samples. Nevertheless, EGCG at 400 mg/kg exhibited lower efficacy in retaining the quality of tuna slices. Thus, EGCG at 200 mg/kg could be used to maintain the color and prolong the shelf life of refrigerated longtail tuna slices.

Smartphone-based colorimetric study of adulterated tuna samples

In this work, a colorimetric analysis of adulterated tuna samples is carried out using both a spectroradiometer and a smartphone as capture devices. Yellowfin tuna (Thunnus albacares) slices were treated with nitrate and nitrite salts, as well as with two different vegetable extracts (beetroot and radish), and the resulting NO₂^- and NO₃^- concentration was analysed using HPLC-DAD. The results indicate that both nitrite and beetroot treatments work properly as colouring agents in tuna, being nitrate also effective. When assessing the effect of radish, the final flesh had a more whitish colour. Overall, this approach allows to obtain colorimetric data which can distinguish among the different adulterating agents.

An innovative spectroscopic approach for qualitative and quantitative evaluation of Mb-CO from myoglobin carbonylation reaction through chemometrics methods

In this work, an innovative approach using K-means and multivariate curve resolution-purity based algorithm (MCR-Purity) for the evaluation and quantification of carboxymyoglobin (Mb-CO) formation from Deoxy-Myoglobin (Deoxy-Mb) was presented. Through a multilevel multifactor experimental design, samples with different concentrations of Mb-CO were created. The UV-Vis spectra of these samples were submitted to K-means analysis, finding 3 clusters. The mean spectra of the clusters were extracted and it was possible to detect 2 totally differentiable groups through peaks 423 and 434 nm, which are wavelengths related to the Mb-CO and Deoxy-Mb components, respectively. The spectral data were subjected to MCR-Purity analysis. The MCR-Purity result successfully described the analyzed reaction, explaining more than 99.9% of the variance (R²) with a LOF of 1.43%. Then, a predictive model of MbCO was created through the linear relationship between MCR-Purity contributions and known concentrations of MbCO. The performance parameters of the created predictive model were R²CV = 0.98, RMSECV = 0.58 and RPDcv = 7.8 for the training set, and R²P = 0.98, RMSEP = 0.7 and RPDp = 6.8 for the test set. Thus, the predictive model presented an excellent performance considering that the Mb-CO variation is comprised between 0 and 21 µM. Therefore, these results demonstrate that the application of the proposed strategy to the analysis of spectral data presenting overlapping bands is feasible and robust.

Undesirable discoloration in edible fish muscle: Impact of indigenous pigments, chemical reactions, processing, and its prevention

Fish is rich in proteins and lipids, especially those containing polyunsaturated fatty acids, which made them vulnerable to chemical or microbial changes associated with quality loss. Meat color is one of vital criteria indicating the freshness, quality, and acceptability of the meat. Color of meat is governed by the presence of various pigments such as hemoglobin, myoglobin (Mb), and so on. Mb, particularly oxy-form, is responsible for the bright red color of fish muscle, especially tuna, and dark fleshed fish, while astaxanthin (AXT) directly determines the color of salmonids muscle. Microbial spoilage and chemical changes such as oxidation of lipid/proteins result in the autoxidation of Mb or fading of AXT, leading to undesirable color with lower acceptability. The discoloration has been affected by chemical composition, post-harvesting handling or storage, processing, cooking, and so on . To tackle discoloration of fish meat, vacuum or modified atmospheric packaging, low- or ultralow-temperature storage, uses of artificial and natural additives have been employed. This review article provides information regarding the factors affecting color and other quality aspects of fish muscle. Moreover, promising methodologies used to control discoloration are also focused.

A Novel Class of Dual-Acting DCH-CORMs Counteracts Oxidative Stress-Induced Inflammation in Human Primary Tenocytes

Carbon monoxide (CO) can prevent cell and tissue damage by restoring redox homeostasis and counteracting inflammation. CO-releasing molecules (CORMs) can release a controlled amount of CO to cells and are emerging as a safer therapeutic alternative to delivery of CO in vivo. Sustained oxidative stress and inflammation can cause chronic pain and disability in tendon-related diseases, whose therapeutic management is still a challenge. In this light, we developed three small subsets of 1,5-diarylpyrrole and pyrazole dicobalt(0)hexacarbonyl (DCH)-CORMs to assess their potential use in musculoskeletal diseases. A myoglobin-based spectrophotometric assay showed that these CORMs act as slow and efficient CO-releasers. Five selected compounds were then tested on human primary-derived tenocytes before and after hydrogen peroxide stimulation to assess their efficacy in restoring cell redox homeostasis and counteracting inflammation in terms of PGE₂ secretion. The obtained results showed an improvement in tendon homeostasis and a cytoprotective effect, reflecting their activity as CO-releasers, and a reduction of PGE₂ secretion. As these compounds contain structural fragments of COX-2 selective inhibitors, we hypothesized that such a composite mechanism of action results from the combination of CO-release and COX-2 inhibition and that these compounds might have a potential role as dual-acting therapeutic agents in tendon-derived diseases.

Effect of squid pen chitooligosaccharide and epigallocatechin gallate on discoloration and shelf-life of yellowfin tuna slices during refrigerated storage

This study evaluated the effects of treatments of squid pen chitooligosaccharide (COS) or epigallocatechin gallate (EGCG) or COS/EGCG mixture (1:1, w/w) at different concentrations (0, 200, and 400 mg/kg) on the discoloration and quality changes in yellowfin tuna slices stored at 4 °C for 12 days. Tuna slices added with 200 and 400 mg/kg of COS (C2 and C4, respectively) showed the lowest reduction in oxymyoglobin and a* value (redness) ascertained by the lower metmyoglobin formation than other samples. Additionally, C2 and C4 samples showed a lower total viable count and TBARS value than the remaining samples. EGCG alone and its mixture with COS exhibited lower efficacy in retaining the quality loss than COS alone. COS at both levels effectively reduced the metMb formation. It maintained the redness with sensory acceptability of slices up to 9 days, and C4 sample prolonged shelf-life for 12 days based on the microbiological limit.

Dual Carbonic Anhydrase IX/XII Inhibitors and Carbon Monoxide Releasing Molecules Modulate LPS-Mediated Inflammation in Mouse Macrophages

Low concentrations of carbon monoxide (CO) were reported to exhibit anti-inflammatory effects when administered in cells by suitable chemotypes such as CO releasing molecules (CO-RMs). In addition, the pH-modulating abilities of specific carbonic anhydrase isoforms played a crucial role in different models of inflammation and neuropathic pain. Herein, we report a series of chemical hybrids consisting of a Carbonic Anhydrase (CA) inhibitor linked to a CO-RM tail (CAI/CO-RMs). All compounds and their precursors were first tested in vitro for their inhibition activity against the human CA I, II, IX, and XII isoforms as well their CO releasing properties, aiming at corroborating the data by means of molecular modelling techniques. Then, their impact on metabolic activity modulation of RAW 264.7 mouse macrophages for 24 and 48 h was assessed with or without lipopolysaccharide (LPS) stimulation. The compounds were shown to counteract the inflammatory stimulus as also indicated by the reduced tumor necrosis factor alpha (TNF-α) release after treatment. All the biological results were compared to those of N-acetylcysteine (NAC) as a reference antioxidant compound. Within the series, two CAI/CO-RM hybrids (1 and 2), bearing both the well-known scaffold able to inhibit CAs (acesulfame) and the cobalt-based CO releasing portion, induced a higher anti-inflammatory effect up to 48 h at concentrations lower than NAC.

Synthesis and Evaluation of Carbonic Anhydrase Inhibitors with Carbon Monoxide Releasing Properties for the Management of Rheumatoid Arthritis

Carbon monoxide (CO) is a gas endogenously produced in humans, reported to exhibit anti-inflammatory and cytoprotective effects at low concentration. In this context, CO releasing molecules (CORMs) are attracting enormous interest. Herein, we report a series of small-molecule hybrids consisting of a carbonic anhydrase (CA; EC 4.2.1.1) inhibitor linked to a CORM tail section (CAI-CORMs). All compounds were screened in vitro for their inhibition activity against the human (h) CA I, II, IV, IX, and XII isoforms. On selected CAI-CORM hybrids, the CO releasing properties were evaluated, along with their pain-relieving effect, in a model of rheumatoid arthritis. One CAI-CORM hybrid (5b) induced a higher pain-relieving effect compared to the one exerted by the single administration of CAI (5a) and CORM (15b) fragments, shedding light on the possibility to enhance the pain relief effect of CA inhibitors inserting a CO releasing moiety on the same molecular scaffold.

Overview on Untargeted Methods to Combat Food Frauds: A Focus on Fishery Products

Authenticity and traceability of food products are of primary importance at all levels of the production process, from raw materials to finished products. Authentication is also a key aspect for accurate labeling of food, which is required to help consumers in selecting appropriate types of food products. With the aim of guaranteeing the authenticity of foods, various methodological approaches have been devised over the past years, mainly based on either targeted or untargeted analyses. In this review, a brief overview of current analytical methods tailored to authenticity studies, with special regard to fishery products, is provided. Focus is placed on untargeted methods that are attracting the interest of the analytical community thanks to their rapidity and high throughput; such methods enable a fast collection of “fingerprinting signals” referred to each authentic food, subsequently stored into large database for the construction of specific information repositories. In the present case, methods capable of detecting fish adulteration/substitution and involving sensory, physicochemical, DNA-based, chromatographic, and spectroscopic measurements, combined with chemometric tools, are illustrated and commented on.

Using Pretreatment of Carbon Monoxide Combined with Chlorine Dioxide and Lactic Acid to Maintain Quality of Vacuum-Packaged Fresh Beef

Due to microbial growth, beef easily gets corrupt in retail conditions, and the color and quality of the meat will be deteriorated. Therefore, hurdle technology, namely, pretreatment of carbon monoxide (CO), chlorine dioxide, and lactic acid, is used for vacuum-packaged beef to decontaminate beef and increase its quality stability. Beef was pretreated with 100% CO (C1), 100% CO and 50 mg/L chlorine dioxide (C2), and 100% CO and 50 mg/L chlorine dioxide and 30 g/L lactic acid (C3). The untreated samples were used as control (CK). During storage, thea⁎color parameters of C1, C2, and C3 were significantly higher than that of CK, indicating CO pretreatment is a good way to maintain color appearance of beef, and chlorine dioxide and lactic acid did not affect the color-protecting role of CO on beef. C3 showed the strongest antimicrobial activity with the lowest total viable counts, followed by C2, C1, and CK. Samples in C3 also showed the lowest total volatile basic nitrogen, pH, thiobarbituric acid reactive substance, and metmyoglobin during the mid-late storage. Moreover, C3 can keep beef with higher unsaturated fatty acids. In conclusion, CO pretreatment combined with chlorine dioxide and lactic acid displayed efficient antimicrobial and color-stability activity for vacuum-packaged beef. It would be a potential way to use pretreatment of CO combined with chlorine dioxide and lactic acid to maintain the quality of vacuum-packaged beef.

The role of monoxide hemoglobin in color improvement of chicken sausage

The role of monoxide hemoglobin (COHb) in improvement of chicken sausage color was investigated. COHb and NaNO₂ synergistically increased a* values. Addition of 0.1% COHb decreased the residual nitrite content in the presence of 0.001% NaNO₂. Compared with controls, the combined treatment resulted in significantly higher nitroso pigment contents while the single treatment resulted in slightly higher nitroso pigment contents. Visible spectrometry indicated that both nitrosohemochrome (NH) and hematin were the main ingredients of pigments extracted from chicken sausage treated with a combination of 0.006% NaNO₂ and 0.6% COHb. Formation of NH and hematin caused an increase in a* values and a decrease in L* values, respectively. COHb showed potential for use in meat product formulations.

Interrelationship between myoglobin and lipid oxidations in oxeye scad (Selar boops) muscle during iced storage

The interrelationship between myoglobin oxidation, lipid oxidation and discolouration in oxeye scad fish during iced storage were investigated. The myoglobin autoxidation rate increased with increasing storage time up to 12 days (p < 0.05) and remained constant thereafter (p > 0.05). Increase in metmyoglobin correlated well with a blue shift from 410 to 408 nm for myoglobin. The soret band of myoglobin decreased with a concomitant decrease in the redness index (p < 0.05). During storage, the extractable haem iron decreased (p < 0.05), while the non-haem iron increased (p < 0.05). Hydrogen peroxide and ferrylmyoglobin concentrations had increased at the end of storage (p < 0.05). The conjugated diene (CD) and peroxide value (PV) of oxeye scad lipids tended to stabilise during the initial phase of storage, increased in the differentiation phase and had declined at the end of storage. However, thiobarbituric acid reactive substances (TBARS) increased markedly (p < 0.05). Overall, lipid and myoglobin oxidations in oxeye scad occurred in a concurrent manner and each process appeared to enhance the other.

Identification of cattle, llama and horse meat by near infrared reflectance or transflectance spectroscopy

Visible and near infrared reflectance spectroscopy (VIS-NIRS) was used to discriminate meat and meat juices from three livestock species. In a first trial, samples of Longissimus lumborum muscle, corresponding to beef (31) llamas (21) and horses (27), were homogenised and their spectra collected in reflectance (NIRSystems 6500 scanning monochromator, in the range of 400-2500 nm). In the second trial, samples of meat juice (same muscle) from the same species (20 beef, 19 llama and 19 horse) were scanned in folded transmission (transflectance). Discriminating models (PLS regression) were developed against "dummy" variables, testing different mathematical treatments of the spectra. Best models indentified the species of almost all samples by their meat (reflectance) or meat juice (transflectance) spectra. A few (three of beef and one of llama, for meat samples; one of beef and one of horse, for juice samples) were classified as uncertain. It is concluded that NIRS is an effective tool to recognise meat and meat juice from beef, llama and horses.

Effects of storage atmosphere and heme state on the color and visible reflectance spectra of salmon ( Salmo salar ) fillets

It has previously been observed that the color of mackerel muscle is dependent on the status of heme as myoglobin and hemoglobin and hence the storage atmosphere. This study gives strong indications of this being the case also in salmon. Three different storage conditions were used to promote the oxidized, reduced, and carbon monoxide (CO) bound forms of heme in salmon and mackerel fillets. Color determination (instrumental color analysis, imaging, and sensory evaluation) and spectroscopic measurements were performed to study how spectral changes corresponded to color variations. Storage in CO significantly increased the redness in mackerel. This was also seen in salmon to such a degree that it was visible over normal levels of salmon carotenoids. Air storage increased the yellowness and reduced the redness in mackerel, but this effect was partly concealed in salmon by the astaxanthin absorption. The spectral differences due to storage condition could be ascribed to the spectral features characterizing heme of different oxidation states and bound to different ligands. The status of heme should therefore always be considered when experiments related to salmon color are performed. The findings could help in the understanding, control, and prediction of color loss in salmon during processing, storage, and transport.

High throughput headspace GC-MS quantitative method to measure the amount of carbon monoxide in treated tuna fish

A robust and dependable headspace HS-GC-MS method has been developed for the determination of carbon monoxide (CO) treated tuna fish. The performance of the method has been evaluated by analyzing spiked and blank samples. The proposed method uses a programmed temperature vaporizing (PTV) injector to implement the HS injection and overcome the negative effects on the column of water contained in the sample. The level of CO could be easily detected in the treated samples, its amount differing markedly from that detected in the untreated samples. Proper oven temperature programming prevented any deterioration of chromatographic performance caused by the accumulation of water, carbon dioxide and other low molecular weight hydrocarbons in the column during serial analyses. The introduction of PTV injection and the restoring of GC column, by oven temperature programming, were crucial for obtaining the required robustness. This procedure assures the run-to-run repeatability necessary for high throughput applications. The method affords linear calibration curves ranging from 50 to 2500 ng/g of CO content in tuna sample.

Effects of lactate-enhancement on surface reflectance and absorbance properties of beef longissimus steaks

A completely randomized block design was used to assess the effects of lactate-enhancement on surface reflectance and absorbance properties of beef longissimus steaks. Loins were divided into sections, assigned to one of four treatments (non-enhanced day 0, non-enhanced day 5, water-enhanced, and 3% lactate), vacuum packaged, stored for 5 days at 4 degrees C, and then cut into steaks that were used to prepare 100% of deoxy-, oxy-, met-, and carboxymyoglobin according to AMSA (1991). Surface color was analyzed using a HunterLab Miniscan Plus Spectrocolorimeter. Lactate-enhanced steaks had the least overall surface reflectance and the darkest surface color (lower L*; P<0.05). For 100% of each myoglobin form, K/S values and ratios (isobestic wavelengths/525 nm) at 474, 525, 572, and 610 also were influenced by lactate-enhancement. Hence, when estimating surface myoglobin forms using K/S ratios, separate 100% myoglobin reference standards should be prepared from both non-enhanced and enhanced steaks.