Development and validation of a quantitative spectrophotometric method to detect the amount of carbon monoxide in treated tuna fish

In recent years carbon monoxide (CO) has been employed by the fishery industry to preserve the fresh appearance of fish products during frozen storage, particularly in vacuum packaged products. CO reacts with oxy-myoglobin to form a stable cherry coloured carboxy-myoglobin complex. We propose a method that allows the quantitative determination of CO in the meat drip of tuna fish by UV–Vis spectroscopy. It consists of: (i) preparations of CO secondary standard solutions titrated against horse heart Mb primary standard solutions; (ii) determination of calibration curves to measure CO concentration in treated and untreated samples. The accuracy of the spectrophotometric method has been evaluated in terms of trueness and precision by using fortified tuna fish samples. The spectroscopic results have been compared with those obtained using a head space gas chromatographic technique (HS-GC–MS). The CO levels measured in tuna fish samples by UV–Vis are substantially lower than those revealed by HS-GC–MS. The origin of this discrepancy is discussed.     

The effect of modified atmosphere packaging with carbon monoxide on the storage quality of master-packaged fresh pork

Modified atmosphere packaging with carbon dioxide is effective for prolonging shelf-life of fresh meat. Addition of carbon monoxide to the system provides the advantage of enhancing meat colour. The study objective was to determine the effect of CO₂-MAP + 0.4% CO, vs. 100% CO₂-MAP, on the bacteriology and colour of retail-ready fresh pork stored for 8 weeks in a master-package system. Total plate counts were not affected and listeria was present on meat from both treatments. Colour was enhanced with the inclusion of CO, while no effect on lipid oxidation was observed. Use of CO in MAP provides sufficient storage life and product colour quality to permit shipment of fresh pork to distant markets. However, given the stable fresh colour of CO-treated meat and the lack of inhibition of pathogen growth by CO, there is concern that CO-MAP under certain conditions may pose a food safety risk.     

冷藏过程中一氧化碳对白乌鱼肉品质的影响

为了使白乌鱼肉在冷藏期间呈现并保持良好色泽,本文初步探讨了一氧化碳(CO)对白乌鱼肉色泽及其他品质的影响。通过分析CO处理对白乌鱼肉颜色、菌落总数、pH、失水率、硬度、咀嚼性、TBA和感官品质的影响,发现随着CO处理天数的增加,鱼肉的a~*值呈先显著上升(p0.05)后下降的趋势,鱼肉贮藏13d时的a~*值为8.66,比新鲜白乌鱼肉的a~*值提高了18.79%;随着CO处理天数的增加,白乌鱼肉的菌落总数、失水率和TBA值呈整体上升趋势,pH值呈先下降后上升趋势,硬度、咀嚼性和感官评分整体呈下降趋势。因此,CO处理白乌鱼肉,可使鱼肉在冷藏期间保持良好的红色,但CO处理对鱼肉在冷藏期间的贮藏稳定性和其他品质无明显影响。因此,用CO处理白乌鱼肉能有效保持白乌鱼肉的色泽。     

Improvement of carbon monoxide analysis in fish meat

Carbon monoxide (CO) treatment of fish meat of tuna, yellowtail, tilapia etc. is not allowed in Japan, since it can maintain the red color for a longer period than the microbiological shelf life of fish meat. The official method for quantification of CO has a problem, in that a part of the CO is lost during the preparation of the fish sample. To solve this problem, we modified the official method in this study. We also applied this modified method to survey the contents of CO in tuna, yellowtail, young yellowtail, and tilapia. As a result, the modified method was found to be more suitable for CO quantification than the official method. An inter-laboratory study by 4 laboratories confirmed that the CO content of many samples of tilapia exceeded the regulation value, apparently due to the higher recovery of CO, compared to the official method. Therefore, it was suggested that the regulation value in the case of tilapia should be changed if this method is introduced as an official method.     

Effect of different concentrations of carbon dioxide and low concentration of carbon monoxide on the shelf-life of fresh pork sausages packaged in modified atmosphere

This paper reports the effects of different concentrations of carbon dioxide and the presence of low levels of carbon monoxide on quality attributes throughout storage of fresh pork sausages. Four pork forelegs (initial pH 5.5-5.7) were used to prepare a total of 120 fresh sausages, which were packaged in different atmospheres containing (%O(2)/%CO(2)/%N(2)): 0/20/80; 0/60/40; 40/20/40; 40/60/0; 80/20/0; and 0.3% CO/30% CO(2)/rest argon. The packs were stored for 20 days at 2±1 °C in the dark. Three packs for each atmosphere were opened every 4 days for subsequent analysis of pH, colour CIE L*, a*, b*, TBARS formation, microbial psychotrophic aerobes and sensory discolouration and off-odour. Results showed that increasing concentrations of carbon dioxide promoted oxidation of both myoglobin and lipids, most probably due to its effect of lowering pH. Therefore, preservation of colour and odour of fresh pork sausages packaged in modified atmosphere was better achieved using atmospheres containing low CO(2) concentrations (20%) rather than high (60%). However, their shelf-life depended also on the concentration of O(2); 20% CO(2) with high O(2) (80%) enhanced the red colour, but shortened shelf-life, while 20% CO(2) in the absence of O(2) extended freshness to 16 days. The atmosphere containing 0.3% CO, together with 30% CO(2), maintained the red colour for 20 days, but failed to keep fresh odour longer than 16 days.     

Influence of the paprika type on redness loss in red line meat products

Paprika, with its high colourant power (measured in ASTA units), imparts higher initial redness to fresh red sausage and fresh chorizo (red line meat products). This higher degree of redness (measured according to the red–green component, a∗, and spectrophotometric colour units) is maintained until the end of the products’ shelf life. However, the pasteurization necessary to reduce the microbial load of paprika can cause alterations to its stability. The addition of natural antioxidants to pasteurized paprika (rosemary extract) was seen to maintain the colour levels of meat products throughout their shelf life. Differences in the colour of meat batches elaborated with paprika of different colourant power could be detected by consumers in a hedonistic test, who evaluated the colour positively.     

含CO气调包装对冷却肉护色效果的研究

本试验采用0.5%CO/60%CO2/39.5%N2(CO组)真空(真空组)、70%O2/30%CO2(高氧组)和60%CO2/40%N2(无氧组)四种不同的气调包装,以及三种不同CO浓度的气调包装分别包装冷却肉并在1±1℃下贮藏,研究CO气调包装对肉色稳定性的影响。结果显示,CO组可明显延长冷却肉色泽稳定的时间,使冷却肉在整个贮存期中都保持鲜艳的红色,优于真空组、高氧组和无氧组,CO可向肉中不断渗透,生成稳定的鲜艳红色的CO-肌红蛋白。     

新鲜猪肉气调保鲜包装技术与设备

本文介绍鲜猪肉气调保鲜包装混合气体的组成、保持鲜肉色泽与防腐保鲜效果和GM型气体比例混合器的结构与性能。通过鲜猪肉的气调包装和真空包装保鲜效果试验得出：在0～6℃温度贮藏14天后，两种包装的保鲜和保持色泽的效果相比较，气调包装鲜猪肉的细菌总数低于真空包装，血色素的指标是真空包装的三倍。研制的GM型气体比例混合器，可使二种气体（O2与CO2或CO2与N2）或三种气体（O2、CO2、N2）任意体积比例混合，气体比例混合的精度（±1％，其标准流量在0．1MPa压力下为2．4m3／h）GM型气体比例混合器的供气量可满足热成型真空充气包装机或其他机型的气调包装操作要求。     

Structural changes of myoglobin in pressure-treated pork meat probed by resonance Raman spectroscopy

Pork meat was pressurised at 600–700 MPa under conditions applicable for non-thermal food preservation and studied by resonance Raman spectroscopy with 413-nm excitation to probe selectively myoglobin, which is the origin of the red colour of meat. The spectra of intact, non-pressurised meat tissue exclusively display the resonance Raman bands of the ferrous deoxy-form of myoglobin whereas upon pressure treatment a new six-coordinated low spin ferrous species is formed (>60%), that is assigned to a bis–histidine complex including the distal histidine 64. This structural change is associated with a shift of the electronic transitions of the haeme and thus affects the colour of the meat. In contrast, solutions containing myoglobin extracted from pressurised and non-pressurised pork meat give rise to resonance Raman spectra characteristic of the ferrous oxy-form of myoglobin, evidently due to the accessibility of the proteins for oxygen in solution. Upon pressure treatment of the extracted myoglobin solution, the oxy-form is partially converted to the met-(like) ferric form implying a pressure-induced oxidation of the haeme. Thus, this structural transition does not only cause a colour change but also may initiate unwanted oxidative side reactions involving further components of meat. Evidently, such effects can be largely avoided when the oxy- to deoxy-myoglobin ratio is kept small prior to pressure treatment.     

The effects of carbon monoxide on Atlantic salmon (Salmo salar L.)

Atlantic salmon were exposed to carbon monoxide (CO) before the fish were percussively killed and gill cut. The fish were compared against a control group treated identically, without CO. Salmon exposed to CO expressed no adverse reactions and were easily stunned by percussion. CO-treated salmon had an earlier onset of rigor mortis and a faster decrease in muscle pH than the control group. No significant difference in drip loss was found between salmon treated with CO and the control. A significantly deeper red colour of both gills and fillets of CO-treated salmon was observed 10 days post mortem. Significantly higher levels of plasma lactate and potassium were found in CO-treated salmon compared to control, as well as a lower level of pCO₂. Exposure to CO did not increase plasma cortisol, sodium, haematocrit or glucose; however, lactate was high. Exposure of salmon or other fish to CO could improve quality and welfare when slaughtered.     

Color stability of frozen whole tilapia exposed to pre‐mortem treatment with carbon monoxide

BACKGROUND: Color of muscle foods plays a major role in consumer perception of meat quality. Carbon monoxide (CO) has been successfully used for improving color of packaged meat and fish products. In this study, we wanted to investigate pre‐mortem treatment of live tilapia using 100% CO for its ability to improve the color of frozen whole tilapia. We compared untreated and CO‐treated whole, gutted tilapia, frozen for 2 and 4 months at ? 20 °C. Frozen tilapia samples were thawed overnight at 4 °C, filleted and analyzed for their color, heme peak wavelength and CO concentration. RESULTS: Euthanasia using CO significantly increased redness (a* value) and lightness (L* value) of tilapia white and red muscle. Frozen storage significantly (P < 0.05) decreased redness of both CO‐treated and untreated tilapia. However, even after 4 months of frozen storage, a*‐value of CO‐treated tilapia was similar to fresh untreated tilapia fillets. Heme peak wavelengths of CO‐euthanized tilapia were higher than in untreated tilapia and there was no significant (P > 0.05) decrease in heme peak wavelengths of CO‐treated tilapia white and red muscle during frozen storage. The CO content of frozen euthanized tilapia fillets was significantly (P > 0.05) higher than in untreated fillets. In general, red muscle tissue of euthanized tilapia had a higher concentration of CO than white muscle. CONCLUSION: Color stability of tilapia fillets was significantly improved by pre‐mortem CO treatment. The color of CO‐treated fillets was retained during frozen storage compared to untreated fillets. Hence, pre‐mortem CO treatment could be used as a new method for improving color of tilapia. Copyright © 2008 Society of Chemical Industry     

The storage life of beef and pork packaged in an atmosphere with low carbon monoxide and high carbon dioxide

Ground beef, beef loin steaks and pork chops were packaged in modified atmospheres of 0.4% CO/60% CO(2)/40% N(2) and 70% O(2)/30% CO(2). In addition ground beef was packaged in clipped chub packs, beef loin steaks were vacuum packaged, and pork chops were packaged in an atmosphere of 60% CO(2)/40% N(2) with each pack containing an O(2) absorber. The packs were stored in the dark at 4 or 8°C for up to 21 days. Meat in 0.4% CO/60% CO(2)/40% N(2) had a stable bright red colour that lasted beyond the time of spoilage. The storage lives in this gas mixture at 4°C, as limited by off-odours, were 11, 14 and 21 days for ground beef, beef loin steaks and pork chops, respectively. The 70% O(2)/30% CO(2) atmosphere resulted in an initially bright red to red colour of the meat, but the colour was unstable and off-odours developed rapidly. The off-odours probably were caused by Brochothrix thermosphacta, which grew in all meat types, or by pseudomonads in ground beef. Meat stored in chub packs, vacuum packs or 60% CO(2)/40% N(2) with an O(2) absorber developed off-odours and microflora similar to those of meat in 0.4% CO/60% CO(2)/40% N(2), but with less acceptable appearances. These results show that a low CO/high CO(2) atmosphere is effective for preserving retail-ready meat. ?     

Shelf life of fresh sausages stored under modified atmospheres

The aim of this study was to investigate differences in modified atmosphere packaging (MAP) for the improvement of the shelf life of fresh meat products. Three different conditions for preserving fresh sausages were tested: MAP1 (20% CO2, 70% O2, and 10% N2), MAP2 (40% CO2 and 60% O2), and MAP3 (40% CO2, 30% O2, and 30% N2). Samples from the MAP2 group had fewer spoilage bacteria, stable red color (no change of a* value), and good physical attributes (high water-holding capacity, little loss from cooking, and low shear force needed for cutting) compared with samples from other treatment groups. Thus, high concentrations of CO2 (40%) and O2 (60%) resulted in a longer shelf life for fresh sausages.     

EFFECT OF HEATING ON RESIDUAL CARBON MONOXIDE CONTENT IN CO-TREATED TUNA AND MYOGLOBIN

Carbon monoxide (CO) can be used by food manufacturers to retain the red color of meat or dark fish prior to vacuum packaging or in the modified atmosphere packaging. Yellowfin tuna steak (c. 1.5 cm) was treated with CO gas, then packaged in a vacuum bag and heated at a constant temperature ranging from 50 to 100C for 30 min. A myoglobin (Mb) solution was prepared from tuna dark muscle and purged with CO gas for comparison. The released CO concentration and the residual CO in the tuna flesh or Mb solution were measured by gas chromatography. The higher level of CO concentration in the vacuum bag from CO‐treated tuna was found for conditions with temperatures above 80C. The content of residual CO in the CO‐treated tuna steaks after heating was much higher than that in untreated flesh. Regardless of the temperature of heating, a ratio of 58–82% CO was released from Mb solution after heating. This suggested that MbCO was not completely dissociated by heating at temperatures ranging from 50 to 100C.     

Color and thiobarbituric acid values of cooked top sirloin steaks packaged in modified atmospheres of 80% oxygen, or 0.4% carbon monoxide, or vacuum

Case-ready fresh beef is typically packaged in a modified-atmosphere with approximately 80% oxygen and 20% carbon dioxide. Recently, USDA approved distribution of fresh meats in a master bag system using 0.4% carbon monoxide (CO). This study compared effects of packaging system (vacuum, 80% oxygen, 0.4% carbon monoxide), fresh meat storage time (7-21 days) and cooking temperature (49-79 °C) on extent of myoglobin denaturation, color and rancidity in cooked top sirloin steaks. Steaks packaged in 80% oxygen or CO retained desirable red color for 14 and 21 days storage, respectively. Steaks stored in 80% oxygen exhibited the greatest TBA values and myoglobin denaturation at all storage times and cooking temperatures. Steaks stored in high oxygen developed brown interior color at internal temperatures as low as 57 °C, the premature browning effect. Premature browning and rancidity associated with steaks packaged in 80% oxygen was prevented by packaging in 0.4% CO or vacuum.     

Carbon Monoxide as a Colorant in Cooked or Fermented Sausages

ABSTRACT:  The study aimed at substituting nitrite with carbon monoxide (CO) in cooked or fermented meat batter products by investigating color and color stability in myoglobin solutions, model meat systems, and full-scale hotdog and salami sausages of pork and beef. For cooked model meat systems and hotdogs at 75 to 80 °C core temperatures, direct flushing with a 1% CO gas mixture during the last stage of the batter chopping produced an initial red color equal to nitrite or more intense than with nitrite. For fermented model meat systems and salami sausages with a final pH of 4.7, pretreatment and storage of ground raw meat in a 1% CO mixture, and later use of the pretreated meat in batters, also formed an initial red color in the final products. The color stability during air and light display of cooked and fermented meat products with CO was inadequate compared to products with nitrite, although the red color of CO products was largely maintained by anaerobic packaging and storage. Spectra of carboxy- and nitrosomyoglobin at pH 4.7 demonstrated higher absorbance for carboxymyoglobin.     

Shelf-life extension and colour stabilisation of beef packaged in a low O(2) atmosphere containing CO: Loin steaks and ground meat

A combination of low O(2), high CO(2) and very low CO was investigated for packaging fresh beef steaks and ground meat. The following atmospheres were used: 70% O(2) + 20% CO(2) + 10% N(2) (CMA); 70% O(2) + 20% CO(2) + 9% N(2) + 1% CO (HOCO) and 24% O(2) + 50% CO(2) + 25% N(2) + 1% CO (LOCO). Bacterial counts showed that LOCO atmosphere greatly reduced psychrotrophic population, so that log cfu cm(-2) was under 7.5 at 29 days of storage at 1 °C. All the objective measurements related to meat colour (a(?), hue, Chroma and metmyoglobin concentration) revealed that the bright-red colour was more stable in both HOCO and LOCO atmospheres, reaching 29 days of storage without appreciable signs of oxidation. Sensory analysis confirmed these results.     

气调包装对冷鲜羊肉保鲜效果的影响研究

研究了单组分气体及不同比例气体组分对鲜羊肉进行气调包装后,对贮藏期间影响品质因素的关键技术指标的影响。试验条件下最优气体配比为CO2比例为20%,O2比例为65%。在此配比条件下,既可以改善并维持冷鲜羊肉良好的鲜红色泽,也可以在贮藏期间保持鲜肉的pH值和TVB-N值在规定的范围内,对延长冷鲜羊肉的贮藏期和保持良好的品质起到了一定作用。     

Color evaluation of carbon monoxide treated porcine blood

The stability of liquid porcine blood, treated with carbon monoxide (CO) at different pH values (7.40, 6.70, and 6.00) up to its complete saturation, was studied. Lowering the pH from 7.40 to 6.70 resulted in a decrease in the amount of CO necessary to obtain 100% carboxyhemoglobin. Further pH lowering to 6.00 did not result in additional reduction in the amount of gas. During 4 days of refrigerated storage CO treated liquid blood maintained, at every pH, a more stable and attractive red color than fresh blood, which was a result of an increase (P<0.05) of a^* (redness) and b^* (yellowness) values and no variation (P>0.05) on L^* (lightness) value. Hue (h^*) and chroma (C^*) decreased in the untreated blood but not in the CO-treated blood. The results indicate that blood saturation with CO yields a product having greater potential for use in meat products without compromising its visual appearance.     

不同冻结方式对草鱼肉挥发性成分的影响

为探明冻结方式对草鱼肉挥发性风味物质的影响,以草鱼背肉和红肉为研究对象,采用新型材料MonoTrap作为固相萃取整体捕集剂,通过电子鼻和气相色谱-质谱联用技术对经过速冻、酒精浸渍冻结和冰柜直接冻结的草鱼背肉和红肉的挥发性风味成分进行分析和鉴定。结果显示,电子鼻可以良好区分新鲜和不同冻结方式处理草鱼背肉和红肉气味,主成分分析显示冰柜直接冻结样品的气味与新鲜样品的气味差异最大。通过气相色谱-质谱检测新鲜、速冻、酒精浸渍冻结及冰柜直接冻结草鱼背肉和红肉,从背肉中分别鉴定出45、33、28?种和22?种挥发性物质,红肉中分别鉴定出49、38、33?种和25?种挥发性物质,以醛类和醇类物质为主。结果表明,戊醛、己醛、庚醛、辛醛、2-辛烯醛、壬醛、2-壬烯醛、癸醛、2-癸烯醛、十一醛、2,4-癸二烯醛、己醇、2-辛烯醇、1-辛烯-3-醇、二甲苯等化合物对草鱼肉总体风味形成有重要贡献。3?种冻结方式中与新鲜样品挥发性物质的种类和相对含量最接近的是速冻后的样品,差异最大是冰柜直接冻结样品。速冻更有利于保持冻结草鱼肉的品质,冻结后草鱼肉的风味接近于新鲜鱼肉。