External Fat Cover Influence on Raw and Cooked Beef 2. Cooking Time, Losses, Press Fluid and Shear Force Values

SUMMARY: The semitendinosus muscle was used in a study of the influence of the external fat cover and the oven temperature on the characteristics of cooked beef. Roasts were cooked either with or without the external fat cover to an internal temperature of 58°C (rare). Two oven temperatures, 163° or 218°C, were used. The roasts cooked at 218°C required a shorter time in the oven than did the roasts cooked at 163°C but the presence or absence of the external fat cover had very little effect on the min per lb. Roasting at an oven temperature of 218°C caused significantly greater total cooking losses than roasting at 163°C. The cooking losses were increased significantly by cooking the roasts with the fat cover on, as compared with removing the external fat The increase was mainly due to an increase in the drip losses. The presence or absence of the external fat cover had a significant influence on the quantity of press fluid obtained from the samples. A greater amount of fluid was pressed from the roasts without the fat cover. The posterior ends of the muscle were more tender (as indicated by Warner Bratzler shear force values) than the anteriomr ends. The lower oven temperature also caused significantly more tender roasts.     

Moisture, Fat and Cholesterol Content of Some Raw; Barbecued and Cooked Organ Meats of Beef and Mutton

The effect of barbecueing and conventional cooking methods on moisture, fat and cholesterol content in brain, heart, kidney, liver, and tongue of local Iraqi; beef and mutton were studied. Moisture, fat and cholesterol content differed significantly (P ≤ 0.05) between raw and barbecued samples and between raw and cooked samples of both beef and mutton organ meats, except for those mentioned. The lower moisture in barbecued and cooked samples probably caused a relative increase in fat and cholesterol content. Minor differences were observed in raw, barbecued and cooked organ meats between beef and mutton in terms of moisture, fat and cholesterol content at similar animal ages.     

Effect of Changes in Intermuscular and Subcutaneous Fat Levels on Cholesterol Content of Raw and Cooked Beef Steaks

Muscle, intermuscular (seam) fat and subcutaneous fat dissected from boneless rib steaks (U.S. Choice quality grade; USDA yield grade 1 to 5) were analyzed for cholesterol content. For raw steaks, the cholesterol content (wet basis) in the fat fractions was greater than 150% of that in the muscle fraction; the difference diminished greatly when steaks were cooked to an internal temperature of 70°C. On an average of all yield grades, cooked intermuscular fat and subcutaneous fat contained about 108 and 122%, respectively, of the cholesterol content in cooked muscle. The percentage of total cholesterol in raw and cooked steaks that was contributed by the combined fat fractions increased significantly with numerical increases in the USDA yield grade. However, the amount of cholesterol per gram of the whole steak was not significantly different among the five yield grades.     

Sensory and Cooking Properties of Beef Steaks and Roasts Cooked with and without External Fat

The effects of removal of external fat prior to cooking on fat and moisture content and sensory properties of cooked beef lean were investigated. Twelve pairs of beef strip loin steaks, eye of round roasts, top round roasts, briskets and arm pot roasts fabricated from USDA Choice carcasses were used. True fat retention was also determined for 36 strip loin steaks trimmed to either 0, 0.6 or 1.3 cm external fat. Cooking yield and sensory traits were adversely affected, by the fat removal, only in those cuts (briskets and arm pot roasts) which were cooked by braising. Fat content of the cooked lean was numerically higher in all cuts cooked with an external fat layer. Retention of intramuscular fat was also higher in strip steaks cooked with an external fat layer.     

Cholesterol Content of Raw and Cooked Beef Longissimus Muscles with Different Degrees of Marbling

The relationships of marbling level (eight levels from “Moderately Abundant” to “Practically Devoid”) and cooking to cholesterol content of beef longissimus muscle steaks were studied. Only raw steaks with “Practically Devoid” marbling contained significantly less cholesterol (wet basis) than did raw steaks with any of the other seven marbling scores. However, steaks cooked to an internal temperature of 60° or 75°C showed no significant differences in cholesterol content among any of the eight marbling groups. The cholesterol content of cooked steaks was 22–48% higher than that of raw steaks when cooked to 60°C and 38–65% higher when cooked to 75°C; cooking reduced the weight of each steak, thereby increasing the cholesterol content of the steak expressed as a percentage of the cooked weight.     

Free Amino Acids of Raw and Cooked Ground Beef and Pork

Ground beef and ground pork were cooked for 15 min on an electric griddle heated to a surface temperature of 121°C. Cooking reduced the total free amino acid (FAA) content from 25.23 to 17.60 mg/25g fresh weight in pork and from 32.77 to 30.09 mg/25g fresh weight in beef. Sixteen FAA were detected in both beef and pork; most individual FAA decreased during heating. Residues remaining after extraction of FAA from raw pork, when rehydrated (70% moisture) and heated (121°C, 15 min), contained only trace amounts of FAA. Free amino acids apparently were not produced under the cooking conditions employed in this study.     

TBA Values and 7-Ketocholesterol in Refrigerated Raw and Cooked Ground Beef

Thiobarbituric acid (TBA) values and 7-ketocholesterol were determined on raw and cooked ground beef patties after 0, 2, and 4 days of storage at 4°C. The mean 7-ketocholesterol at days 0, 2, and 4 was 9.65, 23.8, and 42.3 μg for 100g raw patties and 6.33, 277.9, and 484.7 kg for 100g cooked patties. The TBA values increased after 2 and 4 days for the raw and cooked patties. TBA values and 7-ketocholesterol were correlated with each other for raw (r²= 0.82) and cooked (r²= 0.98) patties. The peak suspected to be 7-ketocholesterol was confirmed by mass spectral analysis. The 7-ketocholesterol in the cooked patties stored two days represented a 0.3% oxidation of the free cholesterol.     

Determination of Moisture, Protein, Fat, and Calories in Raw Pork and Beef By Near Infrared Spectroscopy

The near infrared (NIR) (1100–2500 nanometers) of raw pork and raw beef samples was determined on a Neotec Model 6350 Scanning Spectrocomputer. Spectral curves were correlated with moisture, protein, fat, and calorie data determined by standard methods. A stepwise multiple regression technique was used to determine the optimum wavelengths for predicting each constituent. Correlation coefficients were ? 0.987 for moisture, fat, and calories and 0.885 for protein. The coefficients of variation for each of the nutrients were ? 3.46%.     

Relationships of Ether-Extractable Fat vs Folch Fat and Fat Content vs Cholesterol Content for Beef Longissimus Muscles

The relation between ether-extractable fat and chloroform-methanol (2:1)-extractable fat (or Folch fat) and that between fat and cholesterol were evaluated for raw and cooked beef longissimus muscles. Folch fat values were, on average, 6.2% higher than ether-extractable fat values for raw samples and 13.4% higher for cooked samples. Cholesterol was correlated (P<0.05) with fat for both raw and cooked samples, but correlation coefficients were very low (0.37 or lower). The relation between moisture and fat values also was determined.     

不同熟度牛肉与高水分组织蛋白品质特性的比较研究

使用低场核磁共振、TPA(Texture Profile Analysis)等分析方法对不同熟度牛肉与高水分组织蛋白(High Moisture Texturized Vegetable Protein,HMTVP)的弛豫时间、质构特性进行比较,并结合感官评价实验,寻找HMTVP的目标参照指标,选择最佳HMTVP配方,...     

Percentage Ether Extractable Fat and Moisture Content of Beef Longissimus Muscle as Related to USDA Marbling Score

Percentage fat and moisture values for beef longissimus steaks (trimmed completely of all subcutaneous fat, epimysium, and peripheral muscles) from 518 steer and heifer carcasses of A and B maturity over a wide range in marbling were as follows: Moderately Abundant = 10.42 and 68.14, Slightly Abundant = 8.56 and 69.56, Moderate = 7.34 and 70.35, Modest = 5.97 and 71.35, Small = 4.99 and 72.36, Slight = 3.43 and 73.61, Traces = 2.48 and 74.29, and Practically Devoid = 1.77 and 75.37.     

Cooked Color in High pH Beef Patties as Related to Fat Content and Cooking from the Frozen or Thawed State

Beef patties were processed from high pH (>6.0) beef to contain 5, 10, 15, 20 or 25% fat. Patties were cooked to 71°C from the frozen or thawed state before evaluating color. Neither fat content nor state of patties when cooked exerted any major influence on color, but linear effects (p<0.01) in association with increased fat content included higher L* values and hue angles and lower a* values (15.2% reduction). Higher values for L*, b* (but not for 5% fat patties), and hue angles were observed for patties cooked thawed rather than frozen. The use of high pH beef lessened the effects of increased fat and cooking from the thawed state on increased brown color in cooked patties.     

Algin/Calcium Gel as a Raw and Cooked Binder in Structured Beef Steaks

Structured meat products which could bind raw as well as cooked would be superior to existing structured products. Therefore, the algin/calcium gel system was, studied. Structured beef steaks were made using three levels of sodium alginate and three levels of CaCO₃. Three additional treatments were included as controls. Treatments were subjectively evaluated for six raw parameters: discoloration, color intensity, alginate pocket area, alginate pocket size, percentage fat and raw bind. Treatments were also subjectively evaluated for four cooked parameters: aroma, flavor, mouthfeel and cooked bind. The algin/calcium gel mechanism can be used to produce structured beef steaks which bind in both the raw and cooked state. Optimum ingredient levels were 0.8–1.2% sodium alginate, 0.144–0.216% CaCO₃ with 500 ppm sodium erythorbate.     

Selenium Content of Raw and Cooked Marine Species Consumed in Portugal

The present study evaluates the effects of different cooking methods (grilling, frying and boiling) on selenium contents of six marine species commonly consumed in Portugal. Forty-two composite samples of sardine, horse mackerel, gilthead seabream, silver scabbardfish, hake and octopus were digested in a microwave system and analysed by electrothermal atomic absorption spectrometry. The described method is adequate for the analysis of selenium in marine species and meets the requirements of validation and quality control. Mean selenium contents in raw species ranged from 0.35 mg kg⁻¹ to 1.24 mg kg⁻¹. Cooked samples presented mean selenium contents from 0.38 mg kg⁻¹ to 1.85 mg kg⁻¹ in grilled fish, from 1.22 mg kg⁻¹ to 1.28 mg kg⁻¹ in fried fish and from 0.84 mg kg⁻¹ to 0.87 mg kg⁻¹ in boiled fish. No statistically significant differences were determined for selenium levels in raw and cooked samples and in different marine species. Estimated selenium intake agrees well with recommendations and is far below the Upper Tolerable Nutrient Level. This is the first study concerning the evaluation of the effects of cooking methods on selenium contents of marine species consumed in Portugal.     

Cellulose, Hemicellulose and Lignin Content of Raw and Cooked Processed Vegetables

The NDF, ADF, cellulose, hemicellulose and lignin contents of five frozen vegetables (raw and boiled) and five canned vegetables (two of them fried) have been studied. In general, it was observed that boiling resulted in an increase in the NDF, ADF and cellulose content. There was also a slight increase in hemicellulose values. The lignin contents of most vegetables did not change upon boiling. When the cooking process was frying, a drastic decrease of NDF, ADF, cellulose, and lignin contents occurred, while the amount of hemicellulose changed slightly in the vegetables analyzed.     

Cellulose, Hemicellulose and Lignin Content of Raw and Cooked Spanish Vegetables

The content in NDF, ADF, cellulose, hemicellulose, and lignin of 22 raw and 19 cooked vegetables (14 boiled, and 5 fried) widely consumed among the Spanish population was determined according to the method of Van Soest. Cooking generally increases the NDF, ADF and cellulose content on a dry weight basis. Normal size servings of the vegetables were prepared and their NDF, cellulose, hemicellulose and lignin contents calculated. We observed that, with vegetables of common use, a total amount of 15–20 g/day of these fiber components can be obtained; according to current knowledge this implies beneficial physiological effects for a broad human pathology.     

不同烹调方法对鱼营养价值及感官评价的影响

通过分析鲟鱼和罗非鱼经清蒸、微波、微波烤、烤箱烤、油煎、高压6种不同烹调处理后水分、脂肪含量的变化,探讨烹调后水分、脂肪含量与质构特性和感官特性的相关性,找到适合水产品烹调方式,使水产品的营养价值得到最大的保存率,以此指导人们合理膳食。结果表明：清蒸烹调后水分含量最大,整体可接受性最高。相关性分析表明：烹调后样品的水分含量与多汁性及弹性有显著正相关性,而脂肪含量与硬度有极显著负相关性,与内聚性具有负相关趋势。以质构指标预测感官特性的预测方程构成因鱼种而有所差异。     

Composition of Raw and Cooked Potato Peel and Flesh: Amino Acid Content

The nitrogen and total amino acid contents of Katahdin and Pontiac varieties of potatoes are reported for the peel and flesh, before and after cooking. With the exception of glutamic acid and 7-amino-butyric acid, all of the contents were higher in the peel. Losses of nitrogen and amino acids were minor in boiling whole potatoes but greater in oven baking in the peel or in boiling the peeled potato. Microwave cooking losses were less than in oven baking.