Tenderization and fragmentation of myofibrillar proteins in bovine longissimus dorsi muscle using proteolytic extract from Sarcodon aspratus

The objective of this study was to examine the Sarcodon aspratus extract including protease how to affect tenderness of the bovine longissimus dorsi muscle. In addition, we investigated myofibrillar protein fragmentation, particularly in myosin, and its influence on meat tenderness. Beef loin chunks were marinated with 0.5 g/100 g, 1 g/100 g, and 2 g/100 g powdered S. aspratus extract, 0.2 g/100 mL papain, and distilled water (control), respectively. Although tenderness of meat is increased by adding S. aspratus extract, differences in meat quality traits, such as muscle pH and meat color, were small and not considered to have practical importance between the control and enzyme-treated samples. Furthermore, the S. aspratus extract influenced the myofibril fragmentation index (MFI) as well as protein solubility. The changes in MFI and protein solubility were due to the myofibrillar protein degradation. Through Western blotting, we found that the S. aspratus extract, as well as papain, caused fragmentation of the myosin heavy chain, but the mushroom extract induced more fragmentations of myofibrillar proteins, and caused more tender meat.     

Pre-rigor infusion with kiwifruit juice improves lamb tenderness

The ability of pre-rigor infusion of kiwifruit juice to improve the tenderness of lamb was investigated. Lamb carcasses were infused (10% body weight) with fresh kiwifruit juice (Ac), water (W) and a non-infusion control (C) treatment. Infusion treatment had no effect on lamb hot carcass weight, cold carcass weight and chilling evaporative losses. The infused treatment carcasses of Ac and W had lower (P < 0.05) pH values than C carcasses during the initial 12 h post-mortem. The LD muscles from Ac carcasses were more tender with significantly lower shear force (P < 0.001) compared with C and W carcasses during the six days following infusion with the kiwifruit juice. The enhanced proteolytic activity (P = 0.002) resulting from the infused kiwifruit juice in Ac carcasses was associated with significant degradation of the myofibrillar proteins, appearance of new peptides and activation of m-calpain during post-mortem ageing. Thus, kiwifruit juice is powerful and easily prepared meat tenderizer, which could contribute efficiently and effectively to the meat tenderization process.     

Effect of water activity and temperature on degradation of 5′-inosine monophosphate in a meat model system

The influence of water activity (a_w) (0.7,0.8 and 0.9) and temperature (80° and 120 °C) on the degradation of meat flavor precursor inosine monophosphate (IMP) was studied in a meat fiber model system. Breast and leg muscle from Indian domesticated layer chicken (Gallus gallus) were washed repeatedly with 0.1 mol/l phosphate buffer of pH 6 to obtain pigment free and with minimum content of natural IMP in muscle fiber. The freeze-dried breast and leg meat fiber had a protein content of 86.5±0.48% and 85.6±0.50%, respectively. The IMP contents (mg/100 g) of leg muscle fiber (7.3±0.60) was higher (P?0.05) than in the breast meat fiber (5.1±1.20). The degradation of IMP was temperature-dependent (P?0.05) in both types of meat fiber systems. In the samples of a_w 0.8, the IMP degradation in breast meat fiber system was lower (P?0.05) than in a_w at 0.7 and 0.9 samples, when treated at 80 °C, whereas, there was no significance difference (P>0.05) in the degradation of IMP at a_w 0.7 and 0.9 when heated at 120 °C. The degradation of IMP in leg meat fiber model system at higher a_w (0.9) was more (P?0.05) as compared to lower a_w (0.7 and 0.8) at 80 °C, while the samples treated at 120 °C, the degradation of IMP at a_w 0.8 and 0.9 was more (P?0.05) than at a_w 0.7.     

Eating quality of “Vitela Tradicional do Montado”-PGI veal and Mertolenga-PDO veal and beef

Physicochemical and sensory characteristics were measured in veal and beef from the Portuguese Mertolenga breed having 3 quality labels as follows: Mertolenga-PDO beef and veal which apply to purebred animals and “Vitela Tradicional do Montado”-PGI veal which applies to crossbred animals. Measurements were made in longissimus lumborum muscle aged for 6 days. The temperature 3 h post-mortem (T₃), cooking losses and Warner–Bratzler shear force (WBSF) reflected carcass weight (CW) differences between groups. The pigment content was influenced by age, with beef having higher values than veal. WBSF correlated negatively with intramuscular fat in Mertolenga-PDO beef, but not on veal. WBSF correlated positively with cooking losses and negatively with myofibrillar fragmentation index, tenderness, juiciness and overall acceptability. Cooking losses and juiciness were the main contributors for the tenderness differences. Vitela Tradicional do Montado-PGI and Mertolenga-PDO veal had lighter colour and were considered tender. The three meat types were well discriminated based on pH_u, a* and C* parameters by canonical discriminant analysis.     

Oxidation in HiOx-packaged pork Longissimus muscle predisposes myofibrillar and sarcoplasmic proteins to N-nitrosamine formation in nitrite-curing solution

The effect of meat protein in situ oxidation on the formation of N-nitrosodiethylamine (NDEA) was investigated. Fresh minced pork was untreated (Con) or treated with 700 mg/kg α-tocopherol (Toc) or 300 mg/kg tea polyphenols (PPE), packaged in a HiOx atmosphere (78.8% O₂, 18.8% CO₂, 2.4% N₂), then stored at 2 ± 1 °C for up to 10 days. Crude myofibrillar (MP) or sarcoplasmic (SP) protein (20 mg/mL) extracted from stored meat was reacted with 43 μM sodium nitrite at 80 °C for 1 h. Lipid oxidation was totally inhibited in PPE pork but increased in Con and Toc samples after 10 days. There was significant protein oxidation (losses of sulfhydryls, formation of protein carbonyls) in both MP and SP in all samples during storage. However, the Con group suffered more extensive protein oxidation than Toc and PPE and produced more NDEA (P < 0.05), indicating that protein oxidation promoted nitrosation.     

Thermal effects on chicken and salmon muscles: Tenderness, cook loss, area shrinkage, collagen solubility and microstructure

The objective of this study was to gain insight into the mechanisms underlying heating-induced tenderness in muscle food products by comparing tenderness changes in chicken breast (Pectoralis major) and salmon (Oncorhynchus gorbuscha) during high-temperature treatment. Relationships among changes in chicken breast and pink salmon muscle were investigated for tenderness, cook loss, area shrinkage, collagen solubility and microstructure. Small white muscle samples (D 30 mm×H 6 mm) cut from pink salmon fillets and chicken breast were sealed in small aluminum containers (internal dimension: D 35 mm×H 6 mm) and heated in an oil bath at 121.1 °C for different time intervals up to 2 h to simulate various thermal process durations. The changes in salmon tenderness had 4 phases (rapid toughening, rapid tenderizing, slow toughening and slow tenderizing), while that of the chicken breast only had 2 phases (rapid tenderizing and slow tenderizing). Twenty minutes was found to be a critical heating time in which >85% collagen was solubilized and shear force reached a minimum. Cook loss and area shrinkage were significantly (P<0.05) correlated with shear force change for both the salmon and chicken, while collagen solubility was only significant for the chicken.     

Carcass and meat quality characteristics of Brahman cross bulls and steers finished on tropical pastures in Costa Rica

Forty-eight male calves (3/4 Brahman × 1/4 Charolais) were used to determine carcass cutability and meat tenderness of Longissimus lumborum (LL), Gluteus medius (GM), Semitendinosus (ST) and Psoas major (PM) steaks from lighter weight carcasses of bulls and steers castrated at 3, 7, or 12 mo of age grown under tropical pasture conditions. Steaks from steers had lower (more tender) LL Warner–Bratzler shear force (WBSF) values than those from bulls. Steaks from steers castrated at 3 mo had lower GM WBSF than those from bulls. For PM steaks, those aged 28 d had lower WBSF than those aged 2 d. Steaks aged 28 d had the lowest LL and GM WBSF and steaks aged 2 d had the highest LL, GM, and ST WBSF. Castration at younger ages is recommended because it provides improvement in LL and GM tenderness over bulls with no differences in carcass traits or subprimal yields.     

Carcass measurements and meat quality of Turkish Merino,Ramlic, Kivircik,Chios and Imroz lambs raised under an intensive production system

Effect of breed on carcass measurements and meat quality characteristics were investigated by using 46 lambs from Turkish Merino, Ramlic, Kivircik, Chios and Imroz breeds. Chios and Imroz carcasses had smaller values for carcass quality characteristics. Breed had no significant effect on pH at 45 min and 24 h post-mortem, water holding capacity and cooking loss. Kivircik and Imroz lambs had lower Warner Bratzler shear force values than those of Ramlic and Turkish Merino lambs (P < 0.01). Meat samples from Kivircik lambs had the highest redness value. Differences among breeds for sensory characteristics, except tenderness were not significant. Tenderness scores given to meat samples of Kivircik lambs were significantly higher (P < 0.01) than those of Turkish Merino, Ramlic and Imroz lambs. Indigenous Kivircik breed, which had high carcass quality as those of improved breeds, might be considered for production of better quality meat in Marmara Region of Turkey.     

Consumer evaluation of venison sensory quality: Effects of sex,body condition score and carcase suspension method

Intact fallow bucks (n = 20) and non-pregnant fallow does (n = 24) (Dama dama), in the body condition score (BCS) of 2, 3 and 4 (lean, prime and fat) and rising 2 year old red deer stags (n = 26) (Cervus elaphus) of the same BCS range (2–4) were used in this study to determine the impact of sex, BCS and method of carcase suspension on consumer perception of venison quality. Consumers were asked to evaluate cooked meat samples (M. gluteus medius) on an unstructured line scale for colour, flavour, tenderness, juiciness and overall liking. Meat from both fallow deer and red deer was preferred by consumers when carcases had hung by the pelvic suspension (PS) method compared with the Achilles tendon (AT) method of hanging (p < 0.001). Consumers also noted a difference in colour between sexes in fallow deer venison, with venison from 36 month-old does being darker (p = 0.015), and preferred venison from does over 18–24 month-old bucks. There was a significant difference in the consumer scores for tenderness in red deer stags of BCSs 2 and 4 (p = 0.05) with panellists determining BCS 4 animals to be more tender; however no tenderness differences were observed for fallow deer does compared with bucks.     

Changes in Muscovy duck breast muscle marinated with ginger extract

The effects of ginger extract (GE) marination on the changes in Muscovy duck breast muscle were evaluated. Pectoralis muscles were excised from the carcasses of male Muscovy ducks and marinated for 14 days in GE at 5 °C. Samples were taken at the end of 0, 1, 3, 7 and 14 days of the marination. The results showed that the pH was higher (p < 0.05) in the GE-marinated samples than in control samples and that TBARS values were lower (p < 0.05) in the GE-marinated samples. The SDS–PAGE and western blot results indicated that titin, myosin heavy chain, desmin and α-actinin degraded more rapidly in the GE-marinated samples than in the control samples and that 32- and 30-kDa troponin-T degradation components were also generated in the GE-marinated samples. Our results suggest that GE marination could not only retard lipid oxidation, but also enhance the proteolysis of Muscovy duck breast muscle.     

Comparison of wheat- versus corn-based dried distillers’ grains with solubles on meat quality of feedlot cattle

A considerable amount of information has been generated on the feeding value and impact of corn dried distillers’ grains with solubles (DDGS) on meat quality, whereas little is known about the effects of wheat DDGS on meat quality, and no direct comparison of these two sources of DDGS has been completed. The current study was conducted to examine the objective and subjective carcass and meat quality traits of cattle fed diets containing corn or wheat (20% or 40%) DDGS (DM basis) as compared to a standard barley-based finishing diet (control). In general, meat obtained from animals fed the barley-based control diet was slightly darker in colour (lower chroma and hue at 24 h, P < 0.01) and less tender (highest proportion of tough shears at 2 d and lowest proportion of tender shears at 20 d). Meat from corn DDGS was rated as more tender and palatable than control samples (P < 0.05), and 20% corn samples were rated better for beef flavour intensity (P < 0.01) and desirability (P < 0.05) than 40% corn DDGS samples. In contrast, meat from steers fed wheat DDGS showed intermediate characteristics between steers fed control and corn DDGS diets. Hence, feeding wheat DDGS had no negative effects, and feeding corn DDGS had some positive effects on meat quality characteristics of beef.     

Effect of low voltage electrical stimulation on protein and quality changes in bovine muscles during postmortem aging

This experiment was conducted to determine the influence of low voltage electrical stimulation (ES) on the tenderness development of beef round muscles. Eight steers were slaughtered, and ES applied to one side of each carcass within 90 min of exsanguination. Steaks from M. longissimus dorsi, semimembranosus, adductor, and gracilis were vacuum packaged and aged at 4 °C for 9 d. Star probe, sensory evaluation, Western blot assays of troponin-T and μ-calpain autolysis and 2D-DIGE were conducted. ES resulted in accelerated (P < 0.05) pH decline of the longissimus in the first 24 h postmortem. ES did not influence (P > 0.05) proteolysis and tenderness, but did alter the predominance of metabolic proteins in the soluble fraction of muscle. Aging for 9 d improved tenderness (P < 0.05). The data confirmed that low voltage ES at 90 min of exsanguination had no effect on proteolysis and tenderness development in the longissimus dorsi, semimembranosus, adductor or gracilis in beef.     

Optimisation of the extraction and processing conditions of chamomile (Matricaria chamomilla L.) for incorporation into a beverage

The total phenols, apigenin 7-glucoside, turbidity and colour of extracts from dried chamomile flowers were studied with a view to develop chamomile extracts with potential anti-inflammatory properties for incorporation into beverages. The extraction of all constituents followed pseudo first-order kinetics. In general, the rate constant (k) increased as the temperature increased from 57 to 100 °C. The turbidity only increased significantly between 90 and 100 °C. Therefore, aqueous chamomile extracts had maximum total phenol concentration and minimum turbidity when extracted at 90 °C for 20 min. The effect of drying conditions on chamomile extracted using these conditions was determined. A significant reduction in phenol concentration, from 19.7 ± 0.5 mg/g GAE in fresh chamomile to 13 ± 1 mg/g GAE, was found only in the plant material oven-dried at 80 °C (p ? 0.05). The biggest colour change was between fresh chamomile and that oven-dried at 80 °C, followed by samples air-dried. There was no significant difference in colour of material freeze-dried and oven-dried at 40 °C.     

Physicochemical changes in fresh-cut wax apple (Syzygium samarangenese [Blume] Merrill & L.M. Perry) during storage

Physicochemical changes, such as peel and flesh colours, total anthocyanin content, browning index, firmness, total soluble solid (TSS), titratable acidity (TA), sugar acid ratio (TSS/TA), antioxidant capacity, total phenolic content and ascorbic acid content, in fresh-cut Taaptimjan wax apple fruit stored at 4 ± 2 °C and 12 ± 2 °C for 7 days were investigated. The skin of fresh-cut fruit stored at 4 ± 2 °C showed higher a^∗ value, chroma and total anthocyanin content and lower hue angle than those stored at 12 ± 2 °C. Lightness (L^∗ value) and whiteness index of the fresh-cut fruit flesh stored at 12 ± 2 °C showed significantly lower than those stored at 4 ± 2 °C which related to an significant increase in browning index. Firmness, total soluble solid, titratable acidity and sugar acid ratio did not significant changes during storage. Antioxidant capacity and total phenolic content increased throughout storage. Ascorbic acid content of the fresh-cut fruit stored at 4 ± 2 °C remained constant throughout storage whilst ascorbic content at 12 ± 2 °C decreased and was lower than that at 4 ± 2 °C. At 4 ± 2 °C antioxidant capacity and ascorbic acid content were higher than that stored at 12 ± 2 °C whilst there was no significant difference in total phenolic content. In conclusion, the reduction of whiteness index and the increase in browning index of fresh-cut wax apple flesh were the key factors affecting its quality and storage at 4 ± 2 °C could reduce the change in the flesh colour and maintained the peel colour and nutritional values of fresh-cut wax apple fruit during storage.     

Pre rigor processing,ageing and freezing on tenderness and colour stability of lamb loins

Forty eight lamb carcasses with temperature and pH monitored were obtained from two commercial plants. At 24 h post mortem both loins (M. longissimus) from each carcass were randomly allocated to a) unaged frozen at − 18 °C, (b) aged at − 1.5 °C for 2 weeks before freezing, (c) aged for 3 weeks before freezing and (d) aged for 9 weeks without freezing. Shear force, colour stability and proteolysis were analyzed. Carcasses with a slower temperature and more rapid pH decline had more calpain autolysis, slightly higher shear force and less colour stable compared to that counterpart in general (P < 0.05). However, the shear force values of the loins were all acceptable (< 6 kgF) regardless of different pre rigor processing and ageing/freezing treatments. Furthermore, the loins aged for 2 weeks-then-frozen/thawed had a similar shear force to the loins aged only for 9 weeks suggesting that ageing-then-freezing would result in equivalent tenderness compared to aged only loins for the long-term storage.     

Tenderisation of pork as affected by degree of cold-induced shortening

Porcine M. longissimus dorsi from 12 carcasses were used to study the effect of ante mortem exercise treatment, time of boning and different ageing periods on tenderness and tenderisation in pork. The pigs were randomly allocated into three groups, of which the pigs (in two of them) were exposed to work on a treadmill: (1) 30 min rest after work, then slaughtered; (2) slaughtered without rest after work; and (3) controls, which were not exposed to work before slaughter. At 1 and 6 h post-stunning, samples from right side of each carcass were excised and immediately chilled in icewater until 24 h post-stunning. The left side loins were used as controls and were chilled on the carcasses at 12-14°C for 90 min and then at 2°C before boning at 24 h post-stunning. The effect of ageing, 0 or 7 days at 2°C, was studied. No parameter in this study was significantly affected by ante mortem treatment. WB shear force decreased significantly with increasing boning time and was correlated to the degree of muscle shortening in unaged excised samples. Muscle shortening for the 1 h excised cuts showed an average value of 27·4%, while an average value of only 6·1% was obtained for 6 h excised cuts. Ageing for 7 days resulted in only minor (7·3%) tenderness improvement for the 1 h excised cuts as compared to the 24·5% decrease in WB shear force obtained from the 6 h excised, less cold-shortened cuts. These differences in ageing rate, however, did not result in detectable changes in the degradation profile of myofibrillar proteins as analysed by SDS-PAGE.     

Persistence and activity towards Sitophilus zeamais (Coleoptera: Curculionidae) of pirimiphos-methyl sprayed at different temperatures on maize

The air temperature in storage units in tropical areas frequently exceeds 50°C during the warmest periods of the day. Since protectant insecticides are sprayed on grains under these conditions, such high temperatures may interfere with the insecticidal activity. To assess this possibility we sprayed maize grains with pirimiphos-methyl 500 EC (0.8 ml c.p./l and 1.5 l/t) at different temperatures (25°C, 30°C, 35°C, 40°C, 45°C, and 50°C) and 55% r.h. The grains were then maintained at 27±1°C and 55±5% r.h. throughout the experiment which lasted 90 days. Residues of pirimiphos-methyl on the sprayed grains were analyzed every 30 days. Grain samples were assessed every 15 days after the insecticide spraying for their effect on the maize weevil, Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae). Insect mortality was evaluated after 24 and 48 h of exposure to the treated grain. The level of pirimiphos-methyl residue on maize grains decreased with an increase in storage period and air temperature during the insecticide spraying (varying from 11.0±0.1 to 1.1±0.1 ppm, corresponding to the residue levels at 25°C on the day of the spraying and after spraying at 50°C and 90 days of storage). The same trend was observed for mortality of the maize weevil, which dropped from 95.4±13.3% to 2.5±2.5% after 90 days storage after insecticide spraying at 50°C. These results indicate that temperature at spraying can affect insecticide persistence and activity during storage.     

Effects of elastase from a Bacillus strain on the tenderization of beef meat

The tenderization effect of a new elastase from Bacillus sp. EL31410 was investigated on beef meat. Meat tenderization was done by dipping the meat cut in a solution containing proteolytic enzymes after freeze-dehydration. It was found that a marination time of 4 h was enough for enzyme adsorption. The samples were treated for 4 h in different enzyme solutions and then was stored at 4 °C for 24, 48, 72 h, and subjected to texture measurement, sensory evaluations, biochemical analysis and histological observations. A marked decrease in hardness, by texture measurements, was observed in the meats with papain and elastase and higher sensory scores for tenderness were observed in the meats treated with enzymes than in the control. The papain-treated beef meat received the highest score for tenderness, but the scores given for juiciness and taste were lower than that of the control. Rapid increases of fragmentation of myofibrils from the enzyme-treated meat were observed in the first 24 h of storage, especially for papain-treated meat. Meantime, elastin of myofibrilar structure was selectively degraded by elastase compared with the control when stored at 4 °C for 48 h as shown by electron microscopy. These findings suggest that Bacillus elastase (EL31410) is a promising substitute for papain as a favourable meat tenderizer.     

Mechanisms of superficial micropunctate corneal staining with sodium fluorescein: The contribution of pooling

Purpose

To establish if sodium fluorescein (SFL) dye accumulation within intercellular spaces on the ocular surface contributes to the appearance of superficial punctate corneal staining.

Methods

Thirteen subjects bilaterally wore PureVision™ lenses that had been pre-soaked in ReNu MultiPlus^® multipurpose solution. After 1 h of lens wear, corneal staining with SFL was assessed using a standard slit-lamp technique. Participants who presented with bilateral, corneal staining were selected for further evaluation. A randomly selected eye was rinsed with saline three times. Fellow eyes (control) received no rinsing. After each rinse, the appearance of SFL staining was recorded without any further instillation of the dye. To eliminate any confounding effects of staining due to residual fluorescein in the tear menisci, corneal staining was induced in freshly excised, isolated, rabbit eyes by topical administration of 0.001% PHMB and staining, rinsing and grading were performed as above.

Results

Nine out of 13 subjects presented with bilateral diffuse corneal staining (mean grade ± SD: 2.4 ± 0.7). The mean staining grades in test and control eyes respectively after each of the three rinses were (1) 2.41 ± 0.41, 2.25 ± 0.69 (p = 0.9); (2) 2.34 ± 0.79, 2.1 ± 0.83 (p = 0.8); and (3) 1.71 ± 0.65, 1.60 ± 0.79 (p = 0.6) there was no significant reduction in staining with rinsing (p > 0.05) and no difference was observed between test and control eyes at any sampling-point. Similar observations made in ex vivo rabbit eyes replicated these results.

Conclusions

Pooling or accumulation of SFL solution within intercellular spaces does not appear to contribute to the appearance of superficial micropunctate corneal staining.     

Shelf-life prediction of olive oils using empirical models developed at low and high temperatures

Induction period of the formation of hydroperoxides and conjugated dienes at 50 °C and oxidative stability index at 100–130 °C as the oxidative stability measures of different types of olive oils with a wide range of chemical compositions were determined. Regression models (R² ? 0.95) developed at low and high temperatures showed different contributions of compositional variables (the ratio between monounsaturated and polyunsaturated fatty acids, the content of total tocopherols and phenolics, peroxide value, acid value, and total polar compounds content) to the oxidative stability measures. To estimate the shelf-life of olive oils at low temperature, three empirical models with errors of ±1.5%, <±10%, and ±21.2% were developed.