Stability during cooking of anthelmintic veterinary drug residues in beef

Anthelmintic drugs are widely used for treatment of parasitic worms in livestock, but little is known about the stability of their residues in food under conventional cooking conditions. As part of the European Commission-funded research project ProSafeBeef, cattle were medicated with commercially available anthelmintic preparations, comprising 11 active ingredients (corresponding to 21 marker residues). Incurred meat and liver were cooked by roasting (40 min at 190°C) or shallow frying (muscle 8-12 min, liver 14-19 min) in a domestic kitchen. Raw and cooked tissues and expressed juices were analysed using a novel multi-residue dispersive solid-phase extraction method (QuEChERS) coupled with ultra-performance liquid chromatography-tandem mass spectrometry. After correction for sample weight changes during cooking, no major losses were observed for residues of oxyclozanide, clorsulon, closantel, ivermectin, albendazole, mebendazole or fenbendazole. However, significant losses were observed for nitroxynil (78% in fried muscle, 96% in roast muscle), levamisole (11% in fried muscle, 42% in fried liver), rafoxanide (17% in fried muscle, 18% in roast muscle) and triclabendazole (23% in fried liver, 47% in roast muscle). Migration of residues from muscle into expressed cooking juices varied between drugs, constituting 0% to 17% (levamisole) of total residues remaining after cooking. With the exception of nitroxynil, residues of anthelmintic drugs were generally resistant to degradation during roasting and shallow frying. Conventional cooking cannot, therefore, be considered a safeguard against ingestion of residues of anthelmintic veterinary drugs in beef.     

Effect of method of cooking on identification of heat processed beef using polymerase chain reaction (PCR) technique

Effects of various cooking methods including boiling, roasting, pressure cooking, and pan frying on species determination of beef by PCR was studied. The meat was cooked by boiling at 97.5°C for 140, 200 or 230min, by roasting at 200°C for 80, 120, or 150min or by autoclaving at 120°C for 30, 60, or 90min. The beef sample was pan fried until the meat was acceptable for sensory attributes (45min, meat temperature 115°C, fat temp 173°C) and further cooked until unacceptable. DNA was extracted from samples taken after cooking and a 271bp fragment of the mitochondrial DNA was amplified by PCR. The results indicated that with the exception of pan frying for 80min, beef was determined in all meat samples including the broth and sauce of the roasted meat.     

Cooking effects on sulfonamide residues in chicken thigh muscle

This paper presents the net change by cooking on residues of sulfadiazine (SDZ), sulfamethoxazole (SMX), sulfamonomethoxine (SMM) and sulfaquinoxaline (SQ) in chicken muscles. These sulfonamides (SAs) were fed to chickens at a dietary concentration of 100 mg/kg (each drug) for 7 successive days. On the 7th day of feeding, they were killed and thigh muscles were collected. Muscle was ground, mixed and formed into 10-g “meatballs”. SA residues were determined by high-performance liquid chromatography. By using the usual cooking methods, boiling, roasting and microwaving, the muscles containing SAs were treated for the specified times. Net residues in the muscles cooked by boiling were reduced 45–61% in 12 min. In roast cooking, the SMX, SMM and SQ residues, except for SDZ, were reduced 38–40% in 12 min. No significant reduction of SDZ was found. By the microwave cooking, the four SAs residues were reduced 35–41% in 1 min. Reducing half-lives of SAs in chicken muscles cooked were estimated as follows: 9.3 min for SDZ and 13.2 min for SMX, SMM and SQ in boiling; 18.3 min for SMX, SMM and SQ in roasting; 1.6 min for all the SAs in microwaving.     

INSTITUTIONAL COOKERY OF RESTRUCTURED BEEF STEAKS

Restructured beef steaks were cooked under four institutional cooking methodologies: oven roasting, grill frying, deep fat frying and broiling. The samples were evaluated for fat and moisture contents, cooking loss and texture. Sensory panels evaluated the steaks for texture desirability, flavor desirability, appearance and overall palat-ability. Evaluations were repeated using breaded, restructured beef steaks cooked by the four institutional methods, with grilled unbreaded steaks included for comparison. Deep fat fried, breaded and unbreaded steaks were significantly lower in moisture and higher in fat than those cooked by any other methodology. No significant differences in juiciness, flavor desirability or overall palatability were found between the unbreaded broiled, oven roasted or grilled samples. Broiled and grilled steaks were preferred for texture in the unbreaded and breaded samples. The unbreaded, deep fat fried samples received the lowest scores for all sensory attributes. Breading significantly improved the juiciness, texture and overall palatability of the deep fat fried steaks. For both breaded and unbreaded samples, grill frying was the preferred method of preparation.     

烹制方法对猪肉脂质氧化和挥发性风味物质的作用研究

研究对比了4种烹制方法(煮制、烤制、微波及油炸制(大豆油、花生油和葵花油))对猪肉脂质氧化及挥发性风味成分的影响。结果表明:烹制能够促进猪肉的脂质氧化,经不同方式烹制后,熟制猪肉的过氧化值(POV)和硫代巴比妥酸值(TBA)显著增加(P0.05)。不同熟制猪肉之间脂质氧化程度存在显著性差异(P0.05),其中烤制猪肉的脂质氧化程度最高,其次为微波和水煮,而炸制猪肉的氧化程度最低。气相色谱-质谱(GC-MS)联用技术从熟制猪肉中共分离鉴定出68种挥发性风味成分,主要包括醛类、脂肪烃类、醇类、酮类、酯类等,总挥发性风味化合物含量在221.09(大豆油炸制猪肉)-1084.61 AU×106/g(煮制猪肉)之间。醛类是主要的化合物,占总挥发性风味成分的73.78(葵花油炸制猪肉)-78.79%(烤制猪肉),而己醛是最主要的醛类物质。TBA值与醛类、醇类及总挥发性风味物质呈显著正相关(p0.05),而POV值与挥发性风味物质的相关性不显著(p0.05)。主成分分析法(PCA)能够很好地区分经不同烹制方法得到的熟猪肉。     

Effects of traditional chinese cooking methods on formation of heterocyclic aromatic amines in lamb patties

Different amounts of the potent mutagenic and/or carcinogenic heterocyclic aromatic amines (HAAs) are formed in muscle-based foods under different cooking methods. HAAs (9 varieties) in lamb patties cooked using traditional Chinese cooking methods (roasting, frying, panfrying, and stewing in seasonings) were investigated. The total HAAs contents in roasted, fried, pan-fried, and stewed patties were 4.39-123.15 ng/g, 3.59-43.24 ng/g, 0.71-10.05 ng/g, and 51.07-120.32 ng/g, respectively. Amounts of HAAs increased as cooking time increased. 2-amino-1-methyl-6-phenylimidazo [4,5-b] pyridine (PhIP) was the dominant HAAs in deep roasted and fried samples, while 1-methyl- 9H-pyrido [3,4-b] indole (Harman) and 9H-pyrido [3,4-b] indole (Norharman) were the main HAAs in pan-fried and stewed samples. Types and contents of HAAs formed at different cooking times using different methods are unique. Stewing in seasoning generated a higher HAAs content than the high-temperature cooking methods roasting, frying, and pan-frying.     

Stability studies of the metabolites of nitrofuran antibiotics during storage and cooking

Nitrofuran antibiotics cannot be used in food production within the European Union because of their potential health risks to consumers. The recent discovery of their widespread use in global food industries and the finding of semicarbazide in baby food as a result of packaging contamination have focused attention on the toxicity and stability of these drugs and their metabolites. The stability of the nitrofuran marker residues 3-amino-2-oxazolidinone (AOZ), 3-amino-5-morpholinomethyl-2-oxazolidone (AMOZ), 1-aminohydantoin (AHD) and semicarbazide (SEM) were tested. Muscle and liver of nitrofuran treated pigs were cooked by frying, grilling, roasting and microwaving. Between 67 and 100% of the residues remained after cooking, demonstrating that these metabolites are largely resistant to conventional cooking techniques and will continue to pose a health risk. The concentration of metabolites in pig muscle and liver did not drop significantly during 8 months of storage at -20°C. Metabolite stock and working standard solutions in methanol were also stable for 10 months at 4°C. Only a 10 ng ml^-1 solution of SEM showed a small drop in concentration over this extended storage period.     

不同热加工方式熟化对克氏原螯虾理化性质和风味的影响

通过电子鼻和电子舌及气相色谱-质谱等技术分析油炸（90、120、150、180 s）、空气炸（5、10、15、20 min）和沸水煮（150 s）熟化后克氏原螯虾虾肉中的风味差异。结合不同热加工方式熟化虾肉后理化指标（基础成分、质构、色度、硫代巴比妥酸反应物值）的测定结果,综合评价虾肉品质的变化。结果表明：电子鼻、电子舌能够很好地区分不同热加工方式熟化的虾肉,且随着热加工时间的延长,在主成分分析图中区域划分越明显;在新鲜虾肉和沸水煮虾肉内分别检测出8、16种风味物质,在油炸虾肉内检测出18、18、16、19种风味物质,而在空气炸虾肉内检测出19、20、20、16种风味物质,空气炸虾肉中吡嗪类化合物含量显著高于其他2种热加工方式;随着热加工时间的延长,虾肉内水分含量均逐渐降低,油炸和空气炸虾肉内脂肪含量和硬度逐渐上升,而弹性呈先上升后降低的趋势;不同热加工方式熟化虾肉的品质不一,结合感官鉴定结果,综合分析空气炸15 min的虾肉品质最佳。     

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.     

Purine Content of Raw and Roasted Chicken Broiler Meat

Adenine, guanine and hypoxanthine were determined in raw and roasted broiler parts. The levels of adenine and guanine increased slightly when the meat was cooked. These increases were attributed to moisture and fat losses by the tissues during roasting. The level of hypoxanthine remained constant or decreased in the tissues because some of the purine was removed with the cooking juices. The cooking juices were found to contain high levels of hypoxanthine and only trace amounts of adenine and guanine.     

Mechanisms of Docosahexaenoic and Eicosapentaenoic Acid Loss from Pacific Saury and Comparison of Their Retention Rates after Various Cooking Methods

The docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) contents of Pacific saury (Cololabis saira), a fatty fish and staple of the Japanese diet, have been reported to decrease after cooking. This study compared the DHA and EPA contents remaining in saury after grilling, pan‐frying or deep‐frying to center temperatures of 75, 85, or 95 °C, and examined physical loss, lipid oxidation, and thermal degradation as mechanisms of DHA and EPA loss. Temperature changes inside the saury were monitored using thermocouples, while DHA and EPA contents, oxygen radical absorbance capacity, and measurements of lipid oxidation (that is, carbonyl value and thiobarbituric acid value) were determined chemically. Visualization of temperature distribution inside fish samples during cooking revealed large differences in heat transfer among cooking methods. True retention rates in grilled (DHA: 84 ± 15%; EPA: 87 ± 14%) and pan‐fried samples (DHA: 85 ± 16%; EPA: 77 ± 17%) were significantly higher than deep‐fried samples (DHA: 58 ± 17%; EPA: 51 ± 18%), but were not affected by final center temperatures despite differences in cooking times. Physical loss via cooking losses (grilling and pan‐frying) or migration into frying oil (deep‐frying) accounted for large quantities of DHA and EPA loss, while lipid oxidation and thermal degradation did not appear to be major mechanisms of loss. The antioxidant capacity of saury was not significantly affected by cooking treatments. The results of this study suggest that minimization of physical losses during cooking may increase DHA and EPA contents retained in cooked Pacific saury.     

Heating method and final temperature affect processing characteristics of beef semimembranosus muscle

The effect of thawing and cooking regimes on the processing characteristics and colour of cooked roast beef made from frozen beef cap-on inside round (semimembranosus, adductor and gracilus muscle) was investigated. After thawing in air or water, the cap was removed and the insides were pumped (110%), tumbled (30 min continuously) and then cooked in either constant-temperature water baths or baths where a 10?°C difference was maintained between the roast and the water to an internal temperature of 63 or 80?°C. Purge was higher for insides thawed in air. Insides that were cooked at a constant temperature had higher cook yields the same was seen for lower end-point temperatures. Colour of raw insides thawed in water was slightly redder than insides thawed in air. Thawing and cooking regime did not affect the colour of cooked slices but the higher the end temperature, the higher the Hunter L and the lower the Hunter a and b values. Data from this research suggests that roast beef manufacturers should evaluate thawing and cooking procedures to ensure they optimize their process.     

EFFECTS of FAT-SUBSTITUTES, FAT LEVELS and COOKING METHODS ON the QUALITY of BEEF PATTIES

Ground beef patties containing 2fat levels (5%, 10%), and 3 fat-substitutes (Lean-Bind (LB), Rice-Complete 3 (RC), Sta-Slim 171 (ST)) were processed using 3 cooking methods (microwave, roasting and pan-frying). Patties containing 20% fat, without fat-substitutes, were processed as a control. Textural properties of cooked patties were evaluated using Kramer shear, puncture, and Texture Profile Analyses. Press-juice, cooking losses and color parameters were also measured. Patties containing ST or LB and 10% fat, cooked by pan-flying, were more tender and juicier than other treatments including control, and had higher product yield than the control. ST provided the lowest cooking losses and the highest press-juice due to strong gelation ability and water holding capacity of ST Fat level did not affect color lightness (L*) or redness (a*) of the patties. However, both fat-substitute and cooking method affected L*, a* and b* (yellowness). Pan frying improved press-juice and reduced cooking losses, thus increased product yield, and provided tender patties compared to microwaved and roasted patties.     

KINETICS of QUALITY CHANGE DURING COOKING and FRYING of POTATOES: PART II. COLOR

Color, as a quality attribute of cooked and fried potatoes, is affected by the extent and nature of heat during thermal processing. Improvement of color parameters has been made possible by the increase in knowledge of kinetics of color change. Analysis of kinetic data allows processors to minimize undesirable changes and optimize color retention. the objective of this study was to evaluate kinetics of color change during cooking and frying of potatoes. Potatoes were cut into cylinders (diameter × height: 20 mm × 20 mm for cooking and 10 mm × 20 mm for frying) and cooked in a temperature controlled water bath at 80–100C or fried in a commercial fryer at 160–190C for selected times. Color changes associated with cooked and fried potatoes were evaluated using a tristiumulus colorimeter in the L, a, b mode. For cooked potatoes, L and b values decreased while ΔE and a values increased with time at each cooking temperature. For fried potatoes, L value decreased while a, b and ΔE values increased as frying time increased. A modified first order model was used to characterize color change kinetics of both cooked and fried potatoes based on changes occurring between the initial and a maximum or minimum value. Temperature sensitivity of rate constants was adequately described by the Arrhenius and z‐value models.     

KINETICS of QUALITY CHANGE DURING COOKING and FRYING of POTATOES: PART I. TEXTURE

Kinetics of texture change during cooking and frying of potatoes were evaluated in this study. Potatoes were cut into cylinders (diameter × height: 20 mm × 20 mm for cooking, and 10 mm × 20 mm for frying) and cooked in a temperature controlled water bath at 80–100C or fried in a commercial fryer at 160–190C for selected times. the cooked samples were water cooled while the fried samples were air cooled immediately after the treatment. Test samples were then subjected to a single cycle compression test in a computer interfaced Universal Testing Machine and three textural properties (hardness, stiffness and firmness) were derived from the resulting force‐deformation curves. Texture parameters of cooked potatoes decreased with progress of cooking time and the rate of texture changes associated with each temperature was found to be consistent with two pseudo first‐order kinetic mechanisms, one more rapid than the other. Textural values of fried potatoes were found to increase with frying time and also followed a first order kinetic model. Temperature sensitivity of rate constants was adequately described by Arrhenius and z‐value models.     

Inhibitory effects of pomegranate seed extract on the formation of heterocyclic aromatic amines in beef and chicken meatballs after cooking by four different methods

Beef and chicken meatballs with a 0.5% (w/w) pomegranate seed extract were cooked using four different cooking methods (oven roasting, pan cooking, charcoal-barbecue, and deep-fat frying) and six heterocyclic aromatic amines; IQ, MeIQx, 4,8-DiMeIQx, PhIP, norharman, and harman were observed. In the beef meatballs, the highest inhibitory effects of pomegranate seed extract on heterocyclic aromatic amines formation were 68% for PhIP, 24% for norharman, 18% for harman, 45% for IQ, and 57% for MeIQx. Total heterocyclic aromatic amine formation was reduced by 39% and 46% in beef meatballs cooked by charcoal-barbecue and deep-fat frying, respectively. In the chicken meatballs, the highest inhibitory effects were 75% for PhIP, 57% for norharman, 28% for harman, 46% for IQ, and 49% for MeIQx. When the pomegranate seed extract was added to the chicken meatballs cooked by deep-fat frying, the total heterocyclic aromatic amine formation was inhibited by 49%, in contrast the total heterocyclic aromatic amine contents after oven roasting increased by 70%.     

Composition of Broiler Meat as Influenced by Cooking Methods and Coating

Broiler meat was cooked, by five different cooking methods and analyzed. Cooking methods affected cooking losses as follows: baked < broiled < microwave heated < panfried < pressurized deepfat fried. A coating greatly reduced moisture loss. Protein was highest in breasts, in coated rather than uncoated meat, and in parts microwave heated, deepfat fried and panfried. Crude fat was higher in uncoated thigh meat, cooked by deepfat frying, but the differences in cooking methods were not significant. Higher concentrations of minerals, where significant differences were found, were in poultry after being microwave heated and in uncoated rather than coated meat. Those minerals that were affected by cooking methods on an‘as is’basis included Fe, Mg, Na, and Zn and Fe on a dry weight basis. Those not affected included Ca, P, K, S, Cu, and Mn.     

Aroma profile and consumer liking of salted and dried chicken meat: Effects of desalting and cooking methods

Twenty-four dried and salted broiler breasts, a chicken charqui–like muscle food, were submitted to desalting in cold water and different cooking methods (grilling, roasting, frying with olive oil, and sous-vide cooking). Samples were assessed by levels of thiobarbituric acid reactive substances, volatile compounds, and odor-liking analysis. Desalted and sous-vide cooked samples presented the highest levels of thiobarbituric acid reactive substances and volatile compounds derived from lipid oxidation. Grilling, roasting, and frying promoted an increase of Maillard-derived volatiles in dried salted broiler meat. This difference in aromatic profile led to a high odor acceptability of samples submitted to more intense thermal treatments such as grilling, roasting, and frying. In contrast, prolonged cooking (sous-vide technique) and desalting in cold water led to a marked decline in consumers’ liking due the rise in volatile compounds derived from lipid oxidation. In conclusion, based on the results, it seemed to be reasonable to hypothesize that dried and salted broiler meat submitted to high temperatures during cooking (≈180–200°C) tended to generate high Maillard-derived volatiles, while long cooking times led to a great thermal degradation/oxidation of lipids, which generates high content of lipid-derived volatile components.     

不同工艺即食烤鱼多环芳烃检测方法及变化研究

目的:建立即食烤鱼16种多环芳烃（Polycyclic aromatic hydrocarbons, PAHs）检测方法,分析不同工艺对烤鱼PAHs种类及含量的影响。方法:样品经正己烷提取,采用固相萃取柱净化,二氯甲烷洗脱,高效液相色谱法测定。结果:16种PAH_S相关系数为0.9993~0.9998,检出限为0.20~2.50 μg/kg;加标回收率为64.25%~122.8%,相对标准偏差为1.38%~7.13%。在碳烤、油炸、电烤三种不同熟化方式下,烤鱼中调味料的添加可减少PAHs的生成量;烤鱼中PAHs的种类和含量为碳烤>油炸>电烤,样品中萘、苊烯、菲和芘检出含量较高,碳烤样品PAHs总量高达58.74 μg/kg,明显高于油炸和电烤样品组;熟化时间和温度对烤鱼PAHs种类及含量均有影响,随油炸时间延长、油炸温度增高,样品PAHs检出种类和含量增加明显,其中,萘、苊烯、菲、荧蒽和芘含量增高达3~5倍;随电烤时间和温度的增加,样品中PAHs种类增多,PAHs总量亦提高;通过风险评估,烤鱼加热时间控制在6 min,温度200 ℃以内,摄入频率小于每月2次,食用风险低。结论:建立了烤鱼中16种PAHs的检测方法;进行了不同工艺烤鱼样品中PAHs的种类、含量变化分析及风险评估,为即食烤鱼熟化工艺选择提供依据。