MetMb Content Research Articles

Effect of onion skin powder on color, lipid, and protein oxidative stability of premade beef patty during cold storage

The impact of premade beef patty (BBP) with red onion skin powder (OSP) at 0, 1, 2, and 3% levels on color, lipid, and protein oxidative stability, and infection degree of microorganisms during cold storage was investigated. The objective was to determine the effect of color by L*, a*, b*, and the content of MetMb. The inhibitory effect of OSP on the oxidation of lipid and protein was studied based on TBARS and the carbonyl content of protein in samples at different storage times. TVB-N content was used to characterize the degree of infection of microorganisms and their effect on meat quality. The results showed that the addition of OSP reduced the pH, L *, a*, and b * values of BBP, and improved the hardness, springiness, gumminess, and cohesiveness of BBP, but had no significant effect on the chewiness of BBP (p > 0.05). After 12 days of storage, the carbonyl group and TBARS content in the BBP supplemented with 3%OSP was significantly lower than that in the control group (p < 0.05). Furthermore, the addition of OSP significantly inhibited the TVB-N increase during beef patty storage. These results indicated that OSP has a good research prospect as a natural antioxidant or preservative.

Impact of a Carboxymethyl Cellulose Coating Incorporated with an Ethanolic Propolis Extract on the Quality Criteria of Chicken Breast Meat.

Recently, the demand for composite edible coatings has increased significantly as a new trend to confront the serious processing and storage problems that always arise regarding chicken meat. We aim to develop a carboxymethyl cellulose (CMC) coating containing various concentrations (0, 1, 2, 3, and 4%) of an ethanolic propolis extract (EPE) to maintain the quality and extend the shelf life of chicken breast meat stored at 2 °C for 16 days. The influence of the CMC and EPE coating on the physicochemical and microbiological quality parameters of chicken breast meat, e.g., pH, color, metmyoglobin (MetMb), lipid oxidation (thiobarbituric acid reactive substance, TBARS), and microbiological and sensory analyses, was studied. Significantly lower weight loss and pH (p ≤ 0.05) were noted in the coated samples compared with the uncoated samples (control) over the storage period. MetMb content was significantly reduced (p ≤ 0.05) in the coated samples compared to the control. Additionally, the addition of EPE to CMC was more effective in inhibiting microbial growth, preventing lipid oxidation, and keeping the overall acceptability of coated chicken breast meat compared to the control. This work presents CMC and EPE as alternative preservatives to produce active packaging coatings.

Properties of black carrot extract and its efficacy for improving the storage quality of vacuum packaged fresh meat products

AbstractNatural plant extracts have been widely used in the food industry in recent years as natural colourants, antioxidants and antimicrobials due to consumer health concerns. In this study, the effects of different levels of black carrot water extract (BCWE) (control without BCWE, 100, 200 and 300 ppm) on metmyoglobin (MetMb), lipid oxidation, colour and microbial counts of vacuum‐packed ground beef were evaluated during chilled storage for 15 days. MetMb, pH, lipid oxidation, redness (a*) values and microbial counts of ground beef were significantly (p &lt; 0.01) affected by BCWE treatment. During storage, the lowest lipid oxidation values were determined in the BCWE groups (p &lt; 0.05). BCWE groups had higher a* values and lower MetMb content at the end of storage than control. BCWE contributed to reduce the growth of Enterobacteriaceae. The 200‐ppm BCWE group had approximately 2 log units lower Enterobacteriaceae counts at the end of storage compared to the control. These results showed that the anthocyanin‐rich BCWE is a promising natural additive to overcome the problems in vacuum‐packed ground meat. Consequently, 200‐ppm BCWE can be recommended for use in vacuum‐packed ground beef to prevent discolouration, lipid oxidation and microbial growth during chilled storage.

Antibacterial and antioxidative activity of the essential oil and seed extracts of Artocarpus heterophyllus for effective shelf‐life enhancement of stored meat

This study was designed to examine the in vitro antimicrobial and antioxidant activity of the essential oil and various extracts processed from Jackfruit seed (Artocarpus heterophyllus). Seed extracts obtained from Jackfruit were tested for TPC and TFC, and the TPC of 34.48 ± 1.77 mg GAE/g extract was detected while TFC of 0.19 ± 0.004 mg QE/g extract was found significantly. Phytochemical screening of A. heterophyllus seed extracts using UPLC–QTOF/MS revealed the presence of eight compounds, representing (−)-Epiafzelechin-3-O-(6″-O-acetyl)-β-D-allosepyranoside was the most abundant phenolic compound. Further samples were also subjected to a screening for their possible antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl assay. DPPH analysis revealed that seed extract of A. heterophyllus has satisfactory radical scavenging capacity which could scavenge the free radicals produced during oxidation process in meat. The antioxidant activity can be observed for meat treated with seed extract as the TBA value was decreased in the samples on the addition of seed extract. However, in this study, seed extract treatment exhibited significant increase in MetMb content at 2 and 3 days of storage than in the control. The significance for all comparisons was determined at the p < .05 level. This result indicated that Jackfruit extract can be used commercially for meat shelf-life management. Practical applications Jackfruit seed extract is a natural preservative which improves the shelf-life storage of meat without causing any adverse effects. Natural preservative from plant source always better option when compare with chemical preservative. Jackfruit seed extracts could be used for shelf-life enhancement of stored meat in natural condition without affecting the quality as well as the taste of meat.

Development of a novel quantitative function between spectral value and metmyoglobin content in Tan mutton

This study was aimed to establish a quantitative function between spectral reflectance values and metmyoglobin (MetMb) content in Tan mutton during refrigeration. Near-infrared hyperspectral data combined with generalized two-dimensional correlation spectroscopy (G2D-COS) method to identify characteristic bands and investigate the sequence of chemical waveband changes. Characteristic wavebands identified by G2D-COS analysis had the best performance in predicting the content of MetMb, with a high R2p of 0.849, a low RMSEP of 2.695 and a high RPD of 2.786. The results showed that the G2D-COS may be a powerful tool for describing intensity changes of MetMb band. The partial least square regression method was used to develop the relationships between the spectral values and MetMb content in Tan mutton meat for predicting MetMb content. This study has provided a convenient and rapid non-destructive quantitative method for assessing the color of Tan mutton meat.

Effect of the exposure to oxidation and malondialdehyde on turkey and rabbit meat protein oxidative stability.

The present study aimed at evaluating the effect of the exposure to a strong oxidative environment (100mM NaClO) and the concurrent incubation with different malondialdehyde (MDA) concentrations (0 to 5mM) on protein carbonylation, free thiol groups, total heme pigments, and on the relative concentration of the different myoglobin (Mb) derivatives in turkey thigh and rabbit hind leg meat to elucidate their eventual role in inducing oxidative modifications on the protein fraction. With regard to turkey meat, the addition of a strong oxidant resulted in remarkably higher (P < 0.001) carbonyls along with a reduction in free thiol groups (which become undetectable). The relative concentration of MbO2 and MetMb was significantly affected (P < 0.001) and total heme pigment was reduced by 62% when fresh meat is compared to its oxidized counterpart. The addition of MDA 2.5mM (or greater) resulted in a 1.4-fold increase in carbonyls and a tendency (P = 0.07) has been observed for free thiol groups whose content decreased as the MDA level increased. Overall, the aforementioned results are in agreement with those obtained on rabbit hind leg meat in which a three-fold increase (P < 0.001) in carbonyls and a remarkably higher (P < 0.001) MetMb content coupled with a 53% reduction in free thiol groups were found. No significant differences ascribable to MDA addition were found. In conclusion, exposing turkey and rabbit meat to the same environment resulted in distinctive oxidative changes that might be related to the compositional traits and a species-specific susceptibility of the meat toward oxidation. PRACTICAL APPLICATION: Protein and lipid oxidation have been investigated in different meat types; nevertheless, the knowledge concerning the interaction between these two phenomena is limited. According to their compositional traits (high Polyunsaturated fatty acids (PUFA) and heme pigment content), turkey and rabbit leg meats are particularly susceptible to oxidation. Providing information concerning the oxidative stability of turkey thigh and rabbit hind leg meat exposed to strong oxidative conditions and to a concurrent increasing content of a secondary product of lipid oxidation, the findings of the present study can be useful when proper processing strategies and storage conditions have to be implemented for manufacturing processed products.

Comparative profiling of sarcoplasmic phosphoproteins in ovine muscle with different color stability

The phosphorylation of sarcoplasmic proteins in postmortem muscles was investigated in relationship to color stability in the present study. Although no difference was observed in the global phosphorylation level of sarcoplasmic proteins, difference was determined in the phosphorylation levels of individual protein bands from muscles with different color stability. Correlation analysis and liquid chromatography – tandem mass spectrometry (LC-MS/MS) identification of phosphoproteins showed that most of the color stability-related proteins were glycolytic enzymes. Interestingly, the phosphorylation level of myoglobin was inversely related to meat color stability. As the phosphorylation of myoglobin increased, color stability based on a∗ value decreased and metMb content increased. In summary, the study revealed that protein phosphorylation might play a role in the regulation of meat color stability probably by regulating glycolysis and the redox stability of myoglobin, which might be affected by the phosphorylation of myoglobin.

Effect of black pepper essential oil on the quality of fresh pork during storage

The effect of different concentrations (0, 0.1 and 0.5%, v/v) of black pepper essential oil (BPEO) on thiobarbituric acid reactive substances (TBARS), meat color, the percentage of metmyoglobin (MetMb%), microbiological parameters and total volatile basic nitrogen (TVB-N) of pork loins stored at 4°C for 9days was evaluated. BPEO treatments showed lower TBARS, MetMb%, yellowness (b*) values, Pseudomonas spp. and Enterobacteriaceae count and TVB-N values and higher lightness (L*) and redness (a*) values than the control during storage; the effectiveness of BPEO was dose-dependent. The retardation of the formation of MetMb by adding BPEO ensured higher L* and a* values and lower b* values than the control at 6 and 9days; the MetMb content has a similar trend to the lipid oxidation. The lower TVB-N value of BPEO treatments than the control could be attributed to the inhibition of Pseudomonas spp. and Enterobacteriaceae. Gram-negative bacteria were more sensitive than Gram-positive bacteria to BPEO.

Potential mechanisms of carbon monoxide and high oxygen packaging in maintaining color stability of different bovine muscles

The objectives were to compare the effects of packaging methods on color stability, metmyoglobin-reducing-activity (MRA), total-reducing-activity and NADH concentration of different bovine muscles and to explore potential mechanisms in the enhanced color stability by carbon monoxide modified atmosphere packaging (CO-MAP, 0.4% CO/30% CO2/69.6% N2). Steaks from longissimus lumborum (LL), psoas major (PM) and longissimus thoracis (LT) packaged in CO-MAP, high-oxygen modified atmosphere packaging (HiOx-MAP, 80% O2/20% CO2) or vacuum packaging were stored for 0day, 4days, 9days, and 14days or stored for 9days then displayed in air for 0day, 1day, or 3days. The CO-MAP significantly increased red color stability of all muscles, and especially for PM. The PM and LT were more red than LL in CO-MAP, whereas PM had lowest redness in HiOx-MAP. The content of MetMb in CO-MAP was lower than in HiOx-MAP. Steaks in CO-MAP maintained a higher MRA compared with those in HiOx-MAP during storage. After opening packages, the red color of steaks in CO-MAP deteriorated more slowly compared with that of steaks in HiOx-MAP.

Effects of ε-Polylysine on Physicochemical Characteristics of Chilled Pork

The aim of this paper was to research effects of e-polylysine (e-PL) on physicochemical characteristics of chilled pork during storage. Chilled pork was treated with different concentrations of e-PL. Sensory properties, total bacterial counts (TBC), pH, total volatile base nitrogen (TVB-N), metmyoglobin (MetMb) content, and α-thiobarbituric acid (TBA) of treated and control samples were analyzed periodically during refrigerated storage. Compared to control, significant reductions (p < 0.05) for TBC, pH, TVB-N, and MetMb content of chilled pork treated with e-PL during storage were found in this study. However, there were significant increments in sensory scores, and TBA almost did not change. TVB-N, pH, and log10CFU/g showed a positive linear relationship among them. These results indicated that 1.25 % e-PL could effectively inhibit the growth and reproduction of bacteria and enhance preservative effects of chilled pork. Thus, e-PL has good potential to be a preservative and extends shelf life of chilled pork.

Effect of chitosan film incorporated with tea polyphenol on quality and shelf life of pork meat patties

The objective of this study was to investigate the effect of chitosan (CH) film incorporated with tea polyphenol (TP) on quality and shelf life of pork meat patties stored at 4±1°C for 12 days. The microbiological, physicochemical (pH, thiobarbituric acid-reactive substances (TBARS) values, and metmyoglobin (MetMb)), and sensory qualities were measured on all the samples. A microbiological shelf-life extension of 6 days was achieved for CH and CH-TP treatment groups when compared to the control group. Wrapping with CH-TP composite film tended to retard the increases in TBARS values and MetMb content. CH-TP composite film maintained acceptable sensory quality of pork meat patties throughout the storage. The results indicated that CH-TP composite film could be a promising material as a packaging film for extending the shelf life of pork meat patties.

한우우사 바닥의 톱밥두께가 도축 후 등심의 육질에 미치는 영향

본 연구는 한우우사 바닥면의 톱밥두께가 도축후 등심의 육질에 미치는 영향을 구명하고자 실시하였다. 7개월 령의 비거세 수소 22두를 톱밥이 10, 15 및 20 cm로 깔린 단방우사(<TEX>$3{\times}8\;m^2$</TEX>)에서 27개월령까지 사육한 후 도축하여 등심(M. longissimus) 부위를 <TEX>$4{\pm}0.2$</TEX>에서 9일 동안 저장하였다. 도체성적, pH, 보수력, 드립감량, 가열감량, 전단력, 전자코에 의한 향기패턴 및 관능적 기호도는 톱밥두께에 따른 유의적인 차이가 없었다. 일반성분 함량 및 지방산 조성은 20cm가 가장 높은 조지방 함량과 가장 낮은 n6/n3을 보였다(p<0.05). 저장중 총환원력은 9일째에 10cm가 가장 높았던 반면(p<0.05), TBARS는 가장 낮았다(p<0.05). 표면육색소 함량은 저장기간 동안 10 및 20 cm의 MetMb이 15cm보다 낮았던 반면(p<0.05), OxyMb은 높았다(p<0.05). 표면육색은 저장기간 동안 10 및 20 cm가 15 cm보다 붉은 육색을 나타내었다(p<0.05). This study was carried out to investigate the effect of sawdust-bedded thickness in floors (SBTF) of Hanwoo on meat quality of M. longissimus after slaughter. The 7 mon-aged bulls (22 heads) were housed in single sheds (<TEX>$3{\times}8\;m^2$</TEX>/animal) bedded with sawdust of 10, 15, and 20 cm thickness for 20 mon prior to slaughter. The M. longissimus from carcasses were then stored at <TEX>$4{\pm}0.2^{\circ}C$</TEX> for 9 d. SBTF had no significant effect on carcass traits and pH, water-holding capacity, drip loss, cooking loss, Warner-Bratzler shear force, aroma pattern with electronic nose, and sensory attributes of beef. The 20 cm group had the highest crude fat and the lowest n6/n3 (p<0.05). At 9 d, the 10cm group showed the highest total reducing ability and the lowest TBARS content (p<0.05). During storage, the 10 and 20 cm groups had lower MetMb content, higher OxyMb content, and redder meat color than the 15 cm group (p<0.05).

Quantitative measurement of metmyoglobin in tuna flesh via electron paramagnetic resonance

The potential of electron paramagnetic resonance (EPR) spectroscopy in the quantitative determination of metmyoglobin (metMb) in tuna flesh was examined and compared with conventional visible spectrophotometry (VIS). Both fresh and stored tuna samples were directly subjected to EPR measurement at −150 °C without pigment extraction, and their metMb concentrations ([metMb TUNA] EPR) were determined from a calibration curve. A linear calibration curve with good correlation ( R 2 = 0.987) was obtained by a plot between EPR intensities and the known [metMb CALI] VIS concentrations, where [metMb CALI] VIS is the concentration of metMb obtained from visible spectrophotometry for the stock metMb solution. The results show that differences between [metMb TUNA] EPR and [metMb TUNA] VIS for tuna meats are negligible at low concentrations of metMb. However, [metMb TUNA] EPR tends to be higher than [metMb TUNA] VIS at a higher concentration of metMb. This is probably due to incomplete pigment extraction from tuna samples that have been stored for a long period of time. This results in experimental inaccuracy of [metMb TUNA] VIS at higher concentrations of metMb. The overall results suggest that the EPR method is a suitable technique for quantitative measurement of metMb in tuna meat without pigment extraction. Since the EPR method operates at −150 °C, this technique could also be very useful in determining the metMb content in frozen tuna meat during low-temperature storage without thawing.

냉동변성 방지제가 pH 조절법으로 제조한 닭가슴살 수리미의 냉동저장 중 이화학적 특성에 미치는 영향

냉동변성 방지제가 pH 조절법으로 제조한 닭 가슴살 수리미의 이화학적 특성에 미치는 영향을 파악하기 위하여 C(명태수리미: 수세 2회, 4% 설탕+5% 솔비톨+0.3% 인산염 첨가), 나머지 처리구들은 폐계 가슴살 활용하여 T1(닭 가슴살 수리미: pH 11.0, 0.3% 인산염 첨가), T2(닭 가슴살 수리미: pH 11.0, 5% 솔비톨+0.3% 인산염 첨가) 및 T3(닭 가슴살 수리미 : pH 11.0, 4% 설탕+5% 솔비톨+0.3% 인산염 첨가) 처리구로 하여 시험한 결과를 요약하면 다음과 같다. 일반성분에서 대조구의 조단백질 함량이 처리구에 비해 높았지만, 수분, 조지방 및 조회분 함량은 T3 처리구가 높았다. pH, 보수성 및 콜라겐 함량은 대조구가 모든 처리구에 비해 높았고, 대조구와 모든 처리구는 저장기간이 경과함에 따라 현저하게 감소하였다(p<0.05). 콜레스테롤 함량은 대조구가 처리구에 비해 낮았지만, 근원섬유단백질 함량은 모든 처리구가 대조구에 비해 현저하게 높았다(p<0.05). 가열감량은 T2 처리구가 대조구와 다른 처리구에 비해 낮았다 <TEX>$L^*$</TEX>값, <TEX>$a^*$</TEX>값 및 <TEX>$b^*$</TEX>값은 전 저장기간 동안 모든 처리구가 대조구에 비해 높았고, 처리구간에는 T1 처리구가 T2 및 T3 처리구에 비해 현저하게 높았다(p<0.05). 저장기간이 경과함에 따라 T1과 T3 처리구는 <TEX>$L^*$</TEX>값이 감소하여 냉동저장 직후에 비해 저장 1.5개월에 현저하게 감소하였지만, <TEX>$a^*$</TEX>값은 증가하였다(p<0.05). W값은 냉동저장 직후에는 대조구와 모든 처리구 간에 차이가 없었고, 저장 1.5와 3개월에는 T3 처리구가 대조구와 T1 처리구에 비해 현저하게 높았다(p<0.05). Myoglobin 함량과 met-Mb 비율은 대조구와 모든 처리구 간에 유사하였으며, met-Mb 비율은 저장기간이 경과함에 따라 증가하였다(p<0.05). 경도는 냉동저장 직후에 대조구가 모든 처리구에 비해 높았지만, 저장 1.5와 3개월에는 현저하게 낮았다(p<0.05). 경도는 저장기간이 경과함에 따라 대조구는 냉동저장 직후에 비해 1.5개월에 감소하였지만, 모든 처리구는 냉동저장 직후에 비해 저장 1.5개월에 현저하게 증가하였다.(p<0.05). 응집성과 검성은 냉동저장 직후에 대조구가 모든 처리구에 비해 높았지만, 냉동저장 1.5와 3개월에는 T3 처리구가 대조구와 다른 처리구에 비해 현저하게 높았다(p<0.05). 이상의 결과에서 대조구가 모든 처리구에 비해 pH와 보수성이 높았고, 콜레스테롤 함량이 낮았다. 그러나 냉동변성 방지제 첨가와 pH 조절한 수리미는 저장기간 동안 염용성단백질 함량이 높고 안정된 조직감을 나타내었다. This study was conducted to determine the effect of cryoprotectants (sugar, sorbitol, polyphosphate) on the physico-chemical characteristics of chicken breast surimi manufactured by pH adjustment (pH 11.0) during freezing storage. The final surimi was divided into experimental units to which the following treatments were randomly assigned: C (Alaska pollack surimi: two washings, 4% sugar +5% sorbitol <TEX>${\pounds}'$</TEX> 0.3% polyphosphate additive): T1 (chicken breast surimi: pH 11.0 adjusted, 0.3% polyphosphate additive): T2 (chicken breast surimi pH 11.0 adjusted, 5% sorbitol +0.3% polyphosphate additive); T3 (chicken breast surimi: pH 11.0 adjusted, 4% sugar +5% sorbitol +0.3% polyphosphate additive). The crude protein content of the control was higher than all treated samples, however the moisture, crude fat and crude ash of T3 were higher than the control (p<0.05). The pH, WHC and collagen content of the control were higher than all of the treated samples, and these values decreased with storage time for all treatments and the control (p<0.05). The cholesterol content of the control was lower than all treated samples, but the myofibrillar protein contents of all treated samples were higher than the control (p<0.05). The cooking loss of T2 was lower than the control and the other two treatments (p<0.05). The <TEX>$L^*,\;a^*\;and\;b^*$</TEX> values of all treated samples were higher than those of the control during freezing storage (p<0.05). The W value of T3 at 1.5 and 3 months of freezing storage was higher than the control and T1 (p<0.05). The myoglobin and met-Mb contents of the control were similar to all treated samples, and the met-Mb content of the control and all treated samples increased with storage time (p<0.05). Immediately after freezing, the hardness of the control was higher than all treated samples, however it was lower after 1.5 and 3 months of frozen storage (p<0.05). The cohesiveness and gumminess of the control were higher than all treated samples immediately after freezing, however the values for T3 were higher than those of the control and the other two treatments during frozen storage for 1.5 and 3 months (p<0.05).

The Effect of Freezing and Aldehydes on the Interaction between Fish Myoglobin and Myofibrillar Proteins

The interaction between fish myoglobin (Mb) and natural actomyosin (NAM) extracted from fresh and frozen fish was studied. The quantity of soluble Mb in Mb-NAM extracted was less in frozen than in fresh fish (P < 0.05). However, no differences were observed in Mb that remained in solution following preparation of Mb-NAM from frozen whole fish vs frozen fillets (P > 0.05). MetMb formation in Mb-NAM was generally greater than that observed in control Mb (P < 0.05); the greatest MetMb content occurred in Mb-NAM extracted from frozen whole fish (P < 0.05). The effect of different aldehyde oxidation products on the interaction between fish Mb and NAM was also studied in vitro. The loss of soluble Mb from NAM:Mb preparations was greater in the presence of hexenal and hexanal (P < 0.05) relative to controls, and the degree of solubility loss varied with aldehyde type. Hexenal caused greater OxyMb oxidation than hexanal (P < 0.05). Whiteness of washed NAM and NAM-Mb mixtures decreased following aldehyde addition (P < 0.05). In the absence of Mb, the Ca2+ -ATPase activity of NAM was lower with added hexenal than with hexanal (P < 0.05). However, no differences in Ca2+ -ATPase activity between hexanal and hexenal-treated samples were observed when Mb was present (P > 0.05). Reducing and nonreducing sodium dodecyl sulfate-polyacrylamide gel electrophoresis analyses suggested that both disulfide and nondisulfide covalent linkages contributed to aldehyde-induced cross-linking between Mb and myofibrillar proteins.

Characterization and kinetics studies of water buffalo (Bubalus bubalis) myoglobin

It is generally accepted that dry-aged buffalo (B. bubalis) meat becomes dark faster than bovine (B. taurus) meat, discouraging consumer purchase. We have investigated whether this faster darkening process might depend on structural and/or kinetic differences between buffalo and bovine myoglobins (Mbs). To this end, we have purified to homogeneity buffalo Mb from Longissimus dorsi muscle and obtained both its Mr (17,034.5) and the complete amino acid sequence, which, compared with the bovine one, showed three amino acid substitutions: Dbo141Ebu, Abo19Tbu and Abo117Dbu. As revealed by the 3D structure, they were located on the surface of the protein, far from the heme binding pocket, and did not cause appreciable structural changes. Autoxidation rates of purified buffalo and bovine myoglobins at 37 °C, pH 7.2, were almost identical (0.052±0.001 h−1 and 0.054±0.002 h−1, respectively), as were their oxygen-binding Kd values (3.7±0.1 μM and 3.5± 0.1 μM, respectively). These data indicate that the structure of the heme pockets in the two proteins is similar, with similar functional properties. Moreover, the percent of MetMb values in the purified buffalo and bovine samples, after the same time from slaughtering, were almost identical (57% and 47%, respectively). The results presented here suggest that the faster darkening of buffalo meat depends on factors other than the oxidation rate of its Mb, as, for example, the Mb content (0.393±0.005 g/100 g) and consequently its MetMb content, which is almost twice as high as bovine meat (0.209±0.003 g/100 g), and likely other factors.

Effect of fasting on physical/chemical properties of ordinary muscles in full-cycle cultured Pacific bluefin tuna Thunnus orientalis during chilled storage

Using the full-cycle cultured (FC) Pacific bluefin tuna [body weight 16.3±1.9 kg (pre-fasting group, pre-FG), 14.2±0.9 kg (post-fasting group, post-FG)], changes in the physical/chemical properties of the cephalal parts of dorsal (D) and ventral (V) ordinary muscles (OM) by fasting (6 days) during chilled storage (4°C) were investigated. Condition factors were 26.7 (pre-FG) and 20.3 (post-FG, P < 0.05). Fasting changed the liver color to green. Fasting also decreased the amount of protein and lipid contents of the DOM and VOM of FC tuna. The breaking strength and pH of the DOM and VOM of post-FG tuna were higher (P <0.05) than for pre-FG tuna during storage. In contrast, the glycogen contents of DOM and VOM of post-FG tuna were lower than for pre-FG tuna. The color values (L*, a* and b*) of DOM of post-FG tuna were lower than for pre-FG tuna throughout the storage period. In addition, the metmyoglobin (metMb) content of DOM of post-FG tuna was lower (P <0.05) than that of pre-FG tuna, and the metMb content of VOM of post-FG tuna remained low after fasting. These results indicate that fasting suppresses deterioration (especially meat color) of FC tuna muscles during chilled storage.

Decoloration and Gel‐forming Ability of Horse Mackerel Mince by Air‐flotation Washing

ABSTRACT: The decoloration effects and gel‐forming ability of horse mackerel mince by air‐flotation washing (AFW) was investigated. The lowest residual myoglobin content (RMb) and relative fluorescence intensity (RFI), the highest metmyoglobin (metMb) content and best decoloration effects were recorded for the mince washed with AFW. AFW also effectively improved gel strength in heated surimi. No significant difference in RMb was found when mince was treated with flotation washing using nitrogen, air and ozone. Although the highest metMb content and the lowest RFI were found for the mince washed with ozone, significant differences in whiteness were observed only when the mince was treated with a different gas at 10 or 20 L/min for 5 to 10 min. The physical removal of myoglobin was suggested to be the main factor contributing to accelerated decoloration with AFW.

Effect of met-myoglobin reductase on the color stability of blue fin tuna during refrigerated storage

: To investigate the reducing ability of met-myoglobin (metMb) reductase, browned tuna meat was immersed with/without metMb reductase (0.103 unit/mL) for 120 min at 4°C. The metMb reductase activity of browned tuna meat significantly increased, whereas no significant change was observed in the control sample for the first 10 min of immersion (P > 0.05). After comparing the changes in metMb reductase activity, metMb content, Hunter’s ‘a’ and color, it was observed that the reductase did recover the bright red color. To further confirm the role of metMb reductase in color stability, fresh tuna meat was first immersed in metMb reductase (0.503 unit/mL) or a mixture of reductase and nicotinamide adenine dinucleotide (NADH) (1 mM) solutions at 5°C for 10 min, and then stored at 4°C and relative humidity 100%. No significant changes in metMb accumulation and in metMb reductase activity were observed between samples treated with enzyme alone and enzyme + NADPH (P > 0.05). Changes in metMb reductase activity, metMb, Hunter’s ‘a’ value and color for both the control and treated samples suggested that immersion in metMb reductase could extend the color stability of tuna meat, and that the enzymatic reduction of metMb by its reductase occurred during refrigerated storage.