Effect of different cooking methods on lipid oxidation and formation of volatile compounds in foal meat

The influence of four different cooking methods (roasting, grilling, microwaving and frying) on cooking loss, lipid oxidation and volatile profile of foal meat was studied. Cooking loss were significantly (P < 0.001) affected by thermal treatment, being higher (32.5%) after microwaving and lower after grilling (22.5%) and frying (23.8%). As expected, all the cooking methods increased TBARs content, since high temperature during cooking causes increased oxidation in foal steaks, this increase was significantly (P < 0.001) higher when foal steaks were microwaved or roasted.     

Extension of the shelf-life of foal meat with two antioxidant active packaging systems

The objective of this study was to investigate the effect of antioxidant active system on physico-chemical properties, the microbial counts, lipid and protein stability and the sensory properties' changes of foal steaks during storage time. The experimental packaging systems were: (i) control group was packaged without active film, (ii) ATOX group was packed with active film containing a 2% of an oregano essential oil and (iii) ATGT group was packed with active film containing 1% of a green tea extract. Samples were filled with 80% O₂/20%CO₂ atmosphere and displayed under illumination at 2 °C for 14 days. Microbial populations were reduced up to 3.60 log CFU/g on day 14 of storage with the most pronounced effect being achieved by green tea film. Active films with oregano led to a significant (P < 0.001) inhibition of metmyoglobin formation. The use of oregano active film resulted in a decreased lipid and protein oxidation of foal steaks. Active films with oregano were significantly (P < 0.05) more efficient than those with green tea extended fresh odour and colour from 7 to 14 days compared to the control.     

Effect of different cooking methods on lipid oxidation and formation of free cholesterol oxidation products (COPs) in Latissimus dorsi muscle of Iberian pigs

The aim of this work was to study the influence of different cooking methods (grilled (GR), fried (FP), microwave (MW) and roasted (RO)) on lipid oxidation and formation of free cholesterol oxidation products (COPs) of meat from Iberian pigs that have been fed on an intensive system. Moisture and total lipid content, TBARs, hexanal and COPs were measured in Latissimus dorsi muscle samples. Cooking did not produce changes in total lipid content in meat but induced significantly higher lipid oxidation (TBARs and hexanal values) (p < 0.001) and cholesterol oxidation (COPs) (p < 0.01). When the different cooking methods were studied, the grilled method was the least affected by lipid oxidation (TBARs and hexanal) compared to the others. There were no significant differences among different cooking methods on COPs values. The most abundant cholesterol oxides were both 7α-hydroxycholesterol and 7β-hydroxycholesterol in all groups studied.     

Effects of different cooking methods on the mineral contents of wild and farmed sea bream (Sparus aurata)

The effects of different cooking methods (steaming, boiling, oven cooking, grilling, frying in olive oil, frying in soybean oil, frying in corn oil and frying in sunflower oil) on mineral contents (Ca, Mg, K, Na, Fe, Zn, Cu and Mn) of wild and farmed sea bream (Sparus aurata) were determined. The moisture rate decreased significantly (P < 0.05) after boiling, grilling, oven cooking and frying but remains stable after steaming. The fat content increased with different frying treatments. The Ca, Mg, Na, K and Zn contents of wild and farmed sea bream cooked by almost all methods significantly decreased (P < 0.05). The Cu content in grilled wild and farmed sea bream increased significantly (P < 0.05). Losses of mineral content in fried sea bream were higher than those of fish cooked by other methods. On comparing the raw and cooked fish, the results indicated that cooking had considerable effect on the mineral contents.     

Proximate and fatty acid compositions and sensory acceptability of Hispanic consumers towards rib‐eye steaks from forage‐finished steers

Proximate and fatty acid compositions and sensory acceptability of rib‐eye steaks (fresh and 6 months frozen‐stored) from three forage‐finished steers [S1 (bermudagrass + ryegrass, etc.); S2 (bermudagrass + ryegrass + berseem, etc.); S3 (bermudagrass+berseem+soybean+brown midrib sorghum, etc.)] and one commercial steak (C), cooked by one‐sided and/or two‐sided grilling, were evaluated. All forage‐finished steaks had lower [omega‐6/omega‐3] ratios than C. Sensory liking was assessed by Hispanic consumers. Raw C steak had higher fat and lower protein contents than others (S1, S2 and S3). Concerning raw steaks, S3 had higher liking scores for overall appearance and fat appearance than others. Two cooking methods did not cause significant differences in sensory liking. Juiciness and overall liking of cooked C and S3 (one‐sided grilling) steaks were not significantly different. Purchase intent (after knowing health benefits of forage‐finished steaks) increased from 62.0–73.8% to 69.8–85.7%. Forage‐finished steaks showed a potentially healthier lipid profile than grain‐finished steaks and had market potential towards Hispanic population.     

Lipid oxidative changes throughout the ripening of dry-cured Iberian hams with different salt contents and processing conditions

Hexanal content and TBARs were monitored in Semimembranosus and Biceps femoris muscles throughout the ripening of 46 dry-cured Iberian hams processed with different amounts of salt (6% vs. 3% w/w) and different processing systems (traditional vs. modified). Rancid odour and rancid flavour were sensorially analysed in the final product. Hams processed at higher temperatures during the drying stage, following a traditional system, showed lower values in this phase for hexanal content in both muscles (P<0.001), but TBARs showed the opposite behaviour (P<0.001 and P<0.05 for Semimembranosus and Biceps femoris, respectively). Salt content affected hexanal content of each muscle in a different way. Semimembranosus muscles from traditionally processed hams showed lower rancid flavour scores (P<0.001) while salt did not significantly affect rancid odour or aroma scores (P>0.05). Evidently the effects of salt content and processing temperature, within studied ranges, on lipid oxidation are limited. In fact, increased processing temperature, during the drying stage, does not lead to greater oxidation in dry-cured ham, in spite of the well known pro-oxidant effect of temperature.     

Lipid characteristics in cooked, chill-reheated fillets of Indo-Pacific king mackerel (Scomberomorous guttatus)

Slices of Scomberomorous guttatus cooked by four different methods (microwave cooking, grilling, steaming and shallow fat frying) were kept chilled at 5 °C for 2 days, reheated by microwave and then evaluated for the changes in the lipid characteristics. The total lipid content for raw sample was 6.0 g/100 g which consist of 49.4 g/100 g saturated (SFA), 6.9 g/100 g monounsaturated (MUFA) and 43.8 g/100 g polyunsaturated fatty acids (PUFA). Upon cooking, the total lipids changed to about 7 (microwave), 11 (grilling), 5 (steaming) and 10 g/100 g (shallow fat frying). These changes are significant, with the exception of steam cooking. Cooking did not significantly affect the percentage of NPL, PL, SFA, MUFA and PUFA in the samples. Frying resulted in the change of the SFA/PUFA ratio more than other cooking methods. A significant (P < 0.05) decrease in the content of EPA was only found in the fried samples. A significant (P < 0.05) decrease in the content of DHA in all cooked samples were also obtained. The n-6/n-3 ratio did not change significantly in all cooked and reheated samples, except for shallow fat fried. Reheating did not significantly affect the NPL and PL contents of the fillets, except for microwave cooked samples. Cooking increases the FFA, PV and TBA of samples; reheating enhances the increase.     

A simplified method for numerical simulation of gas grilling of non-intact beef steaks to eliminate Escherichia coli O157:H7

The objective of this work was to develop a numerical simulation method to study the heat transfer process and inactivation of Escherichia coli O157:H7 during gas grilling of non-intact beef steaks (NIBS). A finite difference and optimization algorithm was developed to determine the effective heat transfer parameters during grilling. After validation, these parameters were used in a finite element method to simulate the temperature profiles at various locations of NIBS (2.54 cm in thickness). The computer simulation results showed that E. coli O157:H7 may survive the heating processes if normal grilling conditions for intact beef steaks were used. Computer simulation results also suggested that E. coli O157:H7 might be effectively inactivated if NIBS (2.54 cm) were evenly flipped (every 4 min) and cooked for 16 min during cooking. The result of this study may help the food service industry to develop more adequate grilling methods and conditions to cook NIBS.     

Induced changes in bioactive compounds of kailan-hybrid broccoli after innovative processing and storage

The glucosinolates, sulforaphane, vitamin C and lutein content after several industrial cooking methods on the new kailan-hybrid broccoli and their changes during storage for 45 days at 4 °C were studied. Boiling and sous vide induced the highest glucosinolate loss (80%), while low pressure (LP) steaming, microwaving (MW) and sous vide-MW showed the lowest (40%) loss. Glucoraphanin was the most thermostable glucosinolate. Throughout their commercial life, microwaved and grilled samples showed a decrease in total glucosinolates. Generally, myrosinase activity was completely inhibited after cooking with undetected sulforaphane contents. The initial total vitamin C dropped by up to 58% after cooking and progressively decreased during storage, with sous vide-MW (92%) and microwaving (21%) showing the highest and lowest decrements, respectively. LP steaming and microwaving were the best industrial cooking methods for maintaining the glucosinolate and vitamin C contents, and enhancing up to 7.5-fold the initial lutein content.     

Breadfruit consumption,cooking methods and cultivar preference among consumers in Trinidad,West Indies

This study investigated consumer attitudes, consumption characteristics, the most common cooking methods and cultivar preference for breadfruit (Artocarpus altilis (Park.) Fosberg) in Trinidad, West Indies. Between August and September, 2002, surveys were conducted among 196 breadfruit purchasers, 94 vendors and 32 food service operators. Most purchasers (93.4%) ate breadfruit and liked it 87.4%. The quantity consumed/meal increased significantly (P<0.01) with the frequency of consumption. Most consumers ate breadfruit at lunch (P<0.001) and with fish (P<0.001) as a complement. The main cooking methods were “oil down”, steaming and boiling. Of the two local cultivars, `Yellow' and `White', consumers (83.1%) preferred the taste of `Yellow'. `Yellow' was preferred (P<0.001) for the most common cooking methods and `White' was preferred (P<0.05) for frying. Consumers (83.2%) preferred to eat breadfruit at the mature stage. The vendors and food service operators were aware of these preferences for cultivar, cooking methods and stage of fruit maturity.     

Ability of α-tocopherol,taurine and rosemary,in combination with vitamin C,to increase the oxidative stability of beef steaks packaged in modified atmosphere

Fresh beef steaks were sprayed on the surface with vitamin C (500 ppm), taurine (50 mM), rosemary (1000 ppm) and vitamin E (100 ppm), the three latter in combination with 500 ppm of Vitamin C, packaged in modified atmosphere (70% O₂+20% CO₂+10% N₂) and stored at 1±1 °C for 29 days. Metmyoglobin formation, lipid oxidation (TBARS), instrumental colour (CIE a¹), psychrotrophic bacterial counts (PCA) and sensory discolouration and odour were determined. Results demonstrated that surface application of antioxidant combinations resulted in an effective delay of oxidative deterioration of fresh beef steaks. Shelf life was extended beyond that of control, according to evaluation of sensory attributes. Both combinations of vitamin C with either rosemary or taurine significantly (P<0.01) extended the shelf life of fresh beef steaks by about 10 days. Rosemary was the most effective in delaying oxidation processes. The combination of vitamins E and C was significantly (P<0.01) less effective than those combinations in delaying meat oxidation.     

Innovative Cooking Techniques for Improving the Overall Quality of a Kailan-Hybrid Broccoli

The microbial, physical, sensory and nutritional quality of boiled (vacuum and conventional), steamed, pressure cooked, sous vide, microwaved (sous vide and conventional), deep-fried (vacuum and conventional) and grilled kailan-hybrid broccoli (Bimi®) after cooking was studied. Sous vide microwaving greatly decreased microbial counts, achieving very low psychrophilic and enterobacteria counts (1.1 and 0.2 log CFU g^?1, respectively). Vacuum boiling and sous vide reduced the stem broccoli firmness by approximately 54–58 %, reaching a pleasant and moderate softening. Sous vide, grilling and steaming induced the lowest stem colour changes. Generally, all cooking treatments showed a good overall sensory quality. The total phenolic content (1,148 mg CAE kg^?1 fw) usually increased after cooking, with microwave and grilled treatments registering the highest increases up to 2-fold. Commonly, the total antioxidant capacity (296.6 mg AAE kg^?1 fw) increased after cooking by sous vide, microwaving and frying treatments registering the highest increments, by approximately 3.6-fold. Generally, the cooking process reduced the initial vitamin C content, with vacuum and conventional boiling showing the lowest and highest losses with 27 and 62 %, respectively, while vacuum deep frying preserved the initial value (1,737 mg kg^?1 fw). As a main conclusion, the studied grilling and vacuum-based cooking treatments resulted in better microbial quality, colour, stem firmness and sensory quality than the remaining ones. This maintained or even improved the total antioxidant content of the new kailan-hybrid broccoli studied.     

Beef quality attributes as affected by increasing the intramuscular levels of vitamin E and omega-3 fatty acids

In order to investigate the effects of increasing beef n-3 fatty acid content and the protective effects of vitamin E antioxidant activity on meat quality characteristics, 80 feedlot steers were fed 4 different diets (control, high vitamin E, 10% ground flaxseed or high vitamin E-10% ground flaxseed). While dietary treatments had no effect (P > 0.05) on meat composition or tenderness values, the increase in oxidation products was lower (P = 0.046) in meat from vitamin E supplemented steers and higher (P = 0.006) in meat from flaxseed fed animals. The increase in α-tocopherol tissue levels (P < 0.001) in meat from animals fed flaxseed and increased dietary vitamin E resulted in the lowest drip loss values (P = 0.013). As expected, display time had a large effect on retail traits in both steaks and patties (P < 0.001). While retail traits of steaks were not affected by the dietary treatments (P > 0.05), feeding flaxseed decreased (P < 0.05) ground beef retail scores, which were not corrected by higher levels of dietary vitamin E. Finally, although no effect (P > 0.05) was observed among treatments for sensory attributes in steaks, the correlations of a combined n-3:α-tocopherol ratio against retail and sensory attributes (P < 0.05) suggest that increased n-3 fatty acids levels require increased dietary antioxidants, such as vitamin E to avoid negative effects on meat quality from a loss in oxidative stability.     

Effect of cooking methods on fatty acids,conjugated isomers of linoleic acid and nutritional quality of beef intramuscular fat

The effect of boiling, microwaving and grilling on the composition and nutritional quality of beef intramuscular fat from cattle fed with two diets was investigated. Longissimus lumborum muscle from 15 Alentejano young bulls fed on concentrate or pasture was analyzed. Cooking losses and, consequently, total lipids, increased directly with the cooking time and internal temperature reached by meat (microwaving > boiling > grilling). The major changes in fatty acid composition, which implicated 16 out of 34 fatty acids, resulted in higher percentages in cooked beef of SFA and MUFA and lower proportions of PUFA, relative to raw meat, while conjugated linoleic acid (CLA) isomers revealed a great stability to thermal processes. Heating decreased the PUFA/SFA ratio of meat but did not change its n−6/n−3 index. Thermal procedures induced only slight oxidative changes in meat immediately after treatment but hardly affected the true retention values of its individual fatty acids (72–168%), including CLA isomers (81–128%).     

Shelf life of fresh foal meat under MAP, overwrap and vacuum packaging conditions

The objective of this study was to investigate the physico-chemical properties, the microbial counts and the sensory properties' changes of foal steaks packed under various conditions. The experimental packaging systems were: (i) vacuum packaging (VP), (ii) overwrap packaging and (iii) two modified atmosphere packaging methods (MAP): high O(2) MAP (80% O(2)+20% CO(2)) and low O(2) MAP (30% O(2)+70% CO(2)). The meat was stored at 2°C during 14days and tested for pH, colour, lipid and protein oxidation, microbial counts and sensory assessment of odour, colour and appearance. Of the two MAP, overwrap and VP, both MAP were the most effective treatments for the inhibition of the total viable counts (TVC), Pseudomonas spp., psychrotrophic aerobic bacteria, lactic acid bacteria, Enterobacteriaceae as well as moulds and yeast. According to the sensory evaluation, foal steaks packed under overwrap and MAP treatments resulted unacceptable after 7days of storage, whereas the vacuum-packed meat was still acceptable. Moreover, the redness value decreased significantly (P<0.001) with all treatments during the storage time, except for the vacuum packs, which increased significantly (P<0.001). Finally, foal steaks from overwrap packaging and MAP conditions had a greater increase of TBAR'S values and carbonyl content during the storage time. High O(2) levels affected foal meat quality negatively, while anaerobic conditions extended the meat's shelf life up to 14days.     

Penetration of hydrolysed soy protein-added brine and its effect on yield and pH of beef steaks from the biceps femoris muscle

This study was aimed to evaluate the penetration behaviour of different brines with tumbled beef steaks from the biceps femoris muscle, specifically their interactions with pH and effects on yield. Six muscles from different animals, divided into origin (OP) and insertion (IP) portions, were cut into 60 steaks of 2.5 cm thickness and tumbled for 30 or 60 min. The steaks were tumbled with two brines, with (WTB/HSP) or without (WTB) hydrolysed soy protein (HSP), and steaks that were not tumbled with brine or water were used as controls. Brine penetration was verified by measuring the amount of dye-containing brine (absorbance at 627 nm) recovered from homogenates of four thin (2 mm) slices from the surface of the beef steaks after tumbling. The WTB/HSP steaks exhibited greater (P < 0.05) brine penetration when tumbled for 60 min than for 30 min. The OP steaks showed greater yield and lower pH (P < 0.05) than IP steaks. HSP-added brine increased the water absorption and retention in the first slices of the steaks, and its efficiency was increased with a longer tumbling time. The portion of the biceps femoris muscle used influenced brine absorption and retention, impacting meat yield.     

Effects of four cooking methods on the heavy metal concentrations of sea bass fillets (Dicentrarchus labrax Linne, 1785)

Heavy metals (Pb, Cd, Cr, Co, As, Ni) were analysed in cooked sea bass (Dicentrachus labrax). Different cooking treatments were used (baking, grilling, microwaving and frying). The results obtained were statistically compared with those of raw fish. The Co concentrations were below limits of detection in all samples (<0.05). Furthermore, Cr in fried samples and Ni in raw fish were not detected. Cd was only detected in microwaved samples. The Pb concentrations of microwaved and baked fish were significantly decreased. The As concentrations of fried and microwaved samples were significantly increased. The Cd and As concentrations of the fillets subjected to microwave cooking were 0.741 and 1.41 mg/kg, respectively. However, the As concentration was also significantly increased in fried samples. This value was 2.66 mg/kg. Microwaving and frying are not suitable for sea bass.     

Evaluation of the effects of selected plant-derived nutraceuticals on the quality and shelf-life stability of raw and cooked pork sausages

The effect of lutein (200 μg/g meat), sesamol (250 μg/g meat), ellagic acid (300 μg/g meat) and olive leaf extract (200 μg/g meat) on total viable counts (TVC), pH, water holding capacity (WHC), cooking loss, lipid oxidation (thiobarbituric acid-reactive substances, TBARs), colour stability, texture and sensory evaluation of fresh and cooked pork sausages stored in aerobic or modified atmosphere packs (MAP) was investigated. Addition of sesamol, ellagic acid and olive leaf extract reduced (P < 0.001) lipid oxidation in all packaged raw and cooked pork sausages. Antioxidant potency followed the order: sesamol 250 > ellagic acid 300 > olive leaf extract 200 > lutein 200 for both raw and cooked pork sausages. Addition of sesamol increased (P < 0.001) WHC on days 2 and 12 of MAP storage. Meat addition of lutein, sesamol, ellagic acid and olive leaf extract had no detrimental effect on pH, cooking losses, TVCs, tenderness, juiciness, texture or product flavour. Lutein, sesamol, ellagic acid and olive leaf extract were effective as natural functional ingredients in suppressing lipid oxidation and have the potential to be incorporated into functional raw and cooked pork sausages.     

Effect of different cooking methods on the oxidation,proximate and fatty acid composition of silver catfish (Rhamdia quelen) fillets

The influence of seven cooking methods (boiling, conventional baking, microwave baking, grilling, deep-frying in soybean oil, canola oil, or partially hydrogenated vegetable oil) on the oxidation, proximate and fatty acid composition of silver catfish (Rhamdia quelen) fillets was evaluated. All the treatments reduced moisture and increased the protein content. The free fatty acid content of the fillets was significantly reduced by the different cooking methods, while conjugated diene levels and peroxide values decreased for all fried samples, but remained constant in the samples subjected to the other cooking methods. Boiling and baking increased thiobarbituric acid reactive substances (TBARS), while grilling and frying did not change TBARS. Boiling, baking, and grilling did not affect the silver catfish fillets fatty acid composition. Frying in canola oil increased n−3/n−6 ratio, while frying in soybean oil increased the general polyunsaturated fatty acid content, and frying in hydrogenated vegetable oil incorporated trans fatty acids in the fillets.