Fabricated Beef Product: Effect of Handling Conditions on Microbiological, Chemical, and Sensory Properties

Total microbial count was not adversely affected by lowering the holding temperature of fabricated beef roast from 60°C to 54°C or by 12 hr holding time. If a reduction in holding temperature is anticipated, then initial roast contamination and sanitation of the food facility are of critical importance. A stabilizing period of 20 min at room temperature (～23°C) did not decrease yield, but caused a slight lowering of sensory scores. Tenderness was more acceptable in product held at 54°C compared to 60°C. In general, all sensory evaluation ratings were slightly lower with increased holding time.     

Functional, Sensory, and Microbiological Properties of Restructured Beef and Emu Steaks

Beef and emu steaks were restructured with 5% fibrinogen/0.25% thrombin (F), 0.5% algin/0.5% calcium lactate (A), or 0.5% phosphate/1.5% salt (P). P and A treatments had higher cooked binding strengths and cook yields than the F treatments (P < 0.05). The pH and cook yields of restructured emu were higher than beef (P < 0.05). Binding strength of emu was lower than beef in all binding systems (P < 0.05). F solution had an aerobic plate count (APC) of 39,000/g and increased the microbial count in restructured emu steaks from 940 to 7500/g (P < 0.05). Cooking to 60°C reduced APC to < 250/g (P < 0.05) with progressively greater bacterial kill after cooking to 66°C or 75°C.     

烤牛肉中碳点与消化蛋白酶相互作用机制

近年来,食品热加工过程中所产生食源性碳点（carbon dots,CDs）对人体健康的潜在影响已引起了人们的关注。本实验以牛肉为原料,在280 ℃下烤制30 min并分离纯化出CDs,通过体外模拟消化、荧光光谱、同步荧光光谱、傅里叶变换红外光谱、热力学分析等考察CDs在消化过程中与消化蛋白酶（胃蛋白酶和胰蛋白酶）的相互作用机制。体外模拟消化结果显示CDs与消化蛋白酶可以发生相互作用。荧光光谱分析结果表明CDs以静态猝灭的方式猝灭消化蛋白酶的固有荧光,同步荧光光谱分析结果表明酪氨酸参与了相互作用。热力学分析结果表明CDs与消化蛋白酶的结合方式为静电或疏水相互作用,并且结合后会直接影响胃蛋白酶和胰蛋白酶的二级结构,当CDs浓度为1.0×10－5 mol/L时,胃蛋白酶和胰蛋白酶的相对活力分别下降至（61.11±7.36）%和（51.28±3.62）%,本研究结果可为评估内源性纳米粒子的安全性提供参考。     

Microbiological, Sensory and Chemical Characteristics of Vacuum-Packaged Ground Beef Patties Treated with Salts of Organic Acids

Vacuum-packaged ground beef patties containing sodium lactate (NaL), sodium propionate (NaP), sodium acetate (NaA) and sodium citrate (NaC) at various levels and combinations were stored up to 28 days at 4°C. Addition of sodium lactate alone or in combination with sodium propionate increased shelf life of the patties by decreasing microbiological growth and decreasing negative flavor notes associated with lipid oxidation. Lean color also was improved by addition of sodium lactate alone or in combination with sodium propionate. Lipid oxidation by TBA was only slightly affected by treatment addition or storage.     

Microbiological, Sensory and Chemical Characteristics of Vacuum-Packaged Cooked Beef Top Rounds Treated with Sodium Lactate and Sodium Propionate

Cooked, vacuum-packaged beef top rounds containing 3% sodium lactate (NaL) or 3 or 4% NaL in combination with 0.1 or 0.2% sodium propionate (NaP) were stored for up to 84 days at 4°C. Addition of any of the treatments greatly reduced total Aerobic Plate Counts (APC). Positive flavor notes associated with fresh beef were enhanced by ingredient addition and tended to be highest in roasts with 3% NaL + 0.2% NaP. Cooked roast beef color was enhanced by addition of NaL alone or in combination with 0.1% NaP. Lipid oxidation and water activity were decreased by addition of NaL with NaP and pH and cooked yield were increased with any level or combination of ingredients.     

Triose Phosphate Isomerase as an Endogenous Time-temperature Integrator to Verify Adequacy of Roast Beef Processing

Bovine muscle type had a large influence on the initial activity and heat stability of triose phosphate isomerase (TPI). TPI activity in the round muscles was more heat labile than in the chuck muscles. Residual TPI activity in bovine semimembranosus muscle was determined after cooking using adequate and corresponding inadequate U.S. Department of Agriculture processing schedules. In both water bath and pilot oven studies, TPI activity was similar in adequately processed beef (about 2 U/g) and increased when inadequately processed by reducing the holding time by 0.5 and 1.0 log at each temperature. Taken together, these results suggested that TPI could be used as an endogenous time-temperature indicator to verify processing adequacy of roast beef if the muscle used in the product was known.     

Low Fat Level Effects on Sensory, Shear, Cooking, and Chemical Properties of Ground Beef Patties

Two experiments were conducted to determine the effects of targeted fat level (0, 4, 8, 12, 16, 20%) on sensory, shear, cooking and chemical properties of ground beef patties. Frozen patties from all fat levels were cooked to achieve similar cooking yields. As fat levels decreased, tenderness, juiciness and flavor ratings decreased and shear force increased, with more pronounced differences at lower fat levels. Patties processed with 0% fat were rated lower in juiciness and flavor compared to all other fat levels. These studies suggested that alterations in processing and cooking would probably be necessary to achieve acceptance of extremely low-fat beef patties.     

Survival and Metabolic Activity of Listeria monocytogenes on Ready‐to‐Eat Roast Beef Stored at 4 °C

Three brands of commercial roast beef were purchased and artificially inoculated with a 5‐strain Listeria monocytogenes cocktail at 2 inoculation levels (approximately 3 and 6 Log CFU/g). Although all 3 brands contained sodium diacetate and sodium lactate, inoculated Listeria cocktail survived for 16 d in all 3 brands; significant increases in L. monocytogenes numbers were seen on inoculated Brand B roast beef on days 12 and 16. Numbers of L. monocytogenes increased to 4.14 Log CFU/g for the 3 Log CFU/g inoculation level and increased to 7.99 Log CFU/g for the 6 Log CFU/g inoculation level by day 16, with the pH values being 5.4 and 5.8 respectively. To measure the cell viability in potential biofilms formed, an Alamar blue assay was conducted. Brand B meat homogenate had the highest metabolic activities (P < 0.05). By comparing its metabolic activities to Brands A and C and the inoculated autoclaved meat homogenates, results indicated that the microflora present in Brand B may be the reason for high metabolic activities. Based on the denaturing gradient gel electrophoresis and the Shannon–Wiener diversity index analysis, the “Brand” factor significantly impacted the diversity index (P = 0.012) and Brand B had the highest microflora diversity (Shannon index 1.636 ± 0.011). Based on this study, results showed that antimicrobials cannot completely inhibit the growth of L. monocytogenes in ready‐to‐eat roast beef. Native microflora (both diversity and abundance), together with product formula, pH, antimicrobial concentrations, and storage conditions may all impact the survival and growth of L. monocytogenes.     

Fat Level, High Temperature Cooking and Degree of Doneness Affect Sensory, Chemical and Physical Properties of Beef Patties

Ground beef patties containing either 4 or 20% fat were cooked by electric grill (G) alone or in combination with overhead broiler unit (BG) to be (visually) either medium or well-done. Patties with 20% fat had higher beef flavor intensity, juiciness and tenderness scores, lower Instron shear and compression values, and lower cooking yields than 4% fat patties. However, 4% fat patties cooked to medium, had similar sensory ratings to 20% fat patties cooked well-done. About 20% of patties cooked to medium did not reach recommended internal temperatures and holding times for food safety.     

Sensory, Shear, and Cooking Properties of Lower-Fat Beef Patties Made with Inner Pea Fiber

Lower fat (10% and 14%) ground beef patties containing inner pea fiber as dry powder or as part of a high fat mixture were compared to all‐beef patties (10%, 14%, and 18% fat). Patties processed with pea fiber had improved tenderness and cooking yields and showed less change in thickness during cooking, but required longer cooking times to reach 71 °C compared to all‐beef controls. Beef flavor intensity of pea fiber patties did not differ from 10% and 14% fat all‐beef patties. Different forms of pea fiber usage produced similar patty properties. Use of inner pea fiber in lower fat beef patties improved tenderness and cooking yield, without negative effects on juiciness and flavor.     

Chemical, Microbiological and Sensory Properties of Plain Nonfat Yogurt

Chemical and microbiological properties of plain nonfat yogurt were determined after 2, 6 and 12 days refrigerated storage. Sensory properties were determined after 6 days storage. Viable culture bacteria concentrations ranged from 140 to 8,000 × 10⁶/g and ratios of lactobacillus to streptococcus ranged from 0.18 to 15.4. Chemical criteria used to characterize products included: pH, titratable acidity, lactic and four other organic acids and lactose by HPLC, and 23 major volatile organic compounds by dynamic headspace analysis. Lactic acid concentrations ranged from 7.5 to 9.9 mg/g. Major flavor volatiles in all yogurts included: acetaldehyde, heptane, acetone, diacetyl, and benzothiazole. Untrained sensory panels showed differences for flavor, aroma and acceptability.     

花椒叶提取物对烤牛肉饼杂环胺形成的影响

以牛肉和花椒叶为研究对象,研究花椒叶提取物（Zanthoxylum bungeanum Maxim. leaf extract,ZME）添加量（0.015%、0.030%、0.045%）对烤牛肉饼中杂环胺（heterocyclic amines,HAs）形成的影响。结果表明,与对照组相比,ZME能够显著抑制烤牛肉饼中总HAs的形成（P＜0.05）,对其最大抑制率为39.87%,但对不同种类HAs形成的影响不同。其中,添加0.045% ZME对2-氨基-1-甲基-6-苯基咪唑并[4,5-b]吡啶、2-氨基-3-甲基咪唑并[4,5-f]喹啉、2-氨基-3,4-二甲基咪唑并[4,5-f]喹啉、1-甲基-9H-吡啶并[3,4-b]吲哚和2-氨基-9H-吡啶并[2,3-b]吲哚的抑制率分别达到71.76%、78.02%、49.07%、35.82%和100%;而0.045% ZME却促进2-氨基-3,8-二甲基咪唑并[4,5-f]喹喔啉和9H-吡啶并[3,4-b]吲哚的形成。进一步分析ZME对烤牛肉饼中HAs前体物的影响,结果显示前体物的消耗随着ZME添加量的增加呈降低趋势,相关性分析表明HAs的形成与多种游离氨基酸的消耗显著相关。上述结果表明ZME能显著抑制烤牛肉饼中HAs的形成,为其提高加工食品安全性及更广泛的应用提供理论依据。     

Physical and Sensory Characteristics and Microbiological Quality of Beef from a Partial Hot Fabrication Procedure

Vacuum storage, retail display, microbial content, and palatability were evaluated for beef which had excess fat and muscles from the thin cuts and chuck removed after longissimus pH reached 5.8. Some hot processed cuts were darker in lean color. Deep pectorals and ribeye rolls had minor shape distortions but the physical appearance of these and other cuts was little affected. The partial hot fabrication procedure did not adversely affect sensory attributes including tenderness of the final product.     

Effects of Trimming and Added Connective Tissue on Compositional, Physical and Sensory Properties of Restructured, Pre-cooked Beef Roasts

Restructured beef roasts were prepared using trimmed (intermediate or extensive) and chunked (kidney plate or hand knife) beef shoulder clods with varying levels (0, 10, 20 or 30%) of added connective tissue (flaked with Comitrol^R). Intact beef top rounds (control) and all restructured roasts were water cooked to 62.8°C internal temperature. Increasing connective tissue increased (P<0.05) tenderness and fat of restructured products with no deleterious effect (P>0.05) on product bind. Addition of 30% connective tissue decreased (P<0.05) juiciness and overall acceptability of the products; however, products with addition of 10% or 20% connective tissue were acceptable. Sensory data indicated restructured roasts were as acceptable as intact top rounds.     

苹果与葡萄对烤牛肉饼体外消化过程杂环胺释放的影响

研究外源添加物在消化过程中对蛋白结合态杂环胺（heterocyclic aromatic amines,HAAs）释放的影响。在烤牛肉饼的体外消化实验中以加入新鲜苹果和葡萄泥作为实验组,以未添加新鲜苹果和葡萄泥为对照组,消化液中的游离HAAs和蛋白结合态HAAs分别通过乙酸乙酯和盐酸水解提取,经固相萃取后使用超高效液相色谱-质谱联用仪测定。结果表明：苹果与葡萄的添加并未引起总HAAs含量的显著变化,但都不同程度促进了蛋白结合态HAAs向游离态HAAs的转化,且转化效果随新鲜苹果和葡萄泥添加量增加呈增强趋势。     

不同处理牛肉预煮汁中肌肽含量与抗氧化研究

牛肉预煮汁是目前熟肉制品加工环节的主要副产物,本研究对牛肉预煮汁进行超滤和去离子两种方法处理,采用DPPH法和微生物法测定处理后牛肉预煮汁的抗氧化效果。结果显示:10～100mmol/L的肌肽标准溶液对DPPH自由基有显著的清除能力(P<0.05),肌肽标准溶液浓度与清除率呈高度正相关性r=0.9958;牛肉预煮汁对DPPH自由基具有很强的清除效果,其中,预煮牛肉汁超滤液浓度与清除率呈高度正相关性r=0.9995,而预煮牛肉汁去离子液浓度与清除率呈高度正相关性r=0.9641;从抑菌效应考察牛肉预煮汁的表观抗氧化率得出:牛肉预煮汁的表观抗氧化率随着汁液中肌肽含量的递增呈现极强的正相关性,预煮牛肉汁超滤液与表观抗氧化率相关系数达到0.9977,且预煮牛肉汁超滤液的表观抗氧化率弱于肌肽标准溶液,肌肽标准溶液的抗氧化率又弱于VC,而VC的抗氧化率弱于茶多酚。结论:牛肉预煮汁含有除肌肽以外的更丰富的抗氧化性成分,具有比纯肌肽标准溶液更好的抗氧化效果。     

Chemical and Sensory Properties of Thirteen Major Beef Muscles

Chemical and sensory properties of the following thirteen muscles from ten Angus steers were evaluated: semimembranosus, semitendinosus, adductor, biceps femoris, rectus femoris, gluteus medius, psoas major, longissimus - loin portion (LD-L), longissimus - rib portion (LD-R), triceps, infraspinatus, pectoral, and supraspinatus. Steaks (3.8 cm) were cooked to 70°C internally on open hearth grills for sensory evaluation. Muscles from the round and chuck, excluding the infraspinatus, were generally scored lower by the sensory panel than muscles from the loin and rib. The psoas major, LD-L, LD-R, and infraspinatus were more tender (P < 0.05) than seven other muscles; WBS values followed the same trend. Large ranges were observed among muscles for percent fat, sarcomere length, and total collagen.     

Thawing Prior to Cooking Affects Sensory, Shear Force, and Cooking Properties of Beef Patties

Patties from 6 commercial formulations were cooked to 71°C from either the frozen state or after thawing for 24 to 27 h at 4 °C to eliminate the pink/red color exhibited when cooked to 71 °C from the frozen state. Thawed patties had shorter cooking times, higher cooking yields, and lower shear force peak load and peak energy values. Patties cooked from the thawed state increased in thickness during cooking, while patties cooked from the frozen state decreased in thickness during cooking. Thawing prior to cooking increased sensory evaluation scores except for patties made with carrageenan. Thawing not only eliminated the problem of pink/red color after cooking but also improved sensory, shear force, and cooking properties of beef patties.     

Correlation of Sensory, Instrumental and Chemical Attributes of Beef as Influenced by Meat Structure and Oxygen Exclusion

Correlation of elements contributing to meat flavor quality (MFQ) were examined. Muscle structure influences generation of micro temperature environments that lead to formation of flavor-zones. Generation of such zones was also attributed to a structurally-dependent barrier to oxygen. MFQ was examined in the presence and absence of oxygen. Vacuum storage completely retarded flavor deterioration as marked by chemical markers such as thiobarbituric acid reactive substances and lipid volatiles. Vacuum storage incompletely affected changes in sensory attributes; it partially retarded development of painty, cardboard, bitter and sour flavors and limited loss of desirable flavors such as cooked beef/brothy and browned/caramel. Bivariate plots of factor solutions resulting from multivariate principal components analysis proved a suitable method to graphically present statistical correlations between experimental treatments and sensory, chemical, and instrumental attributes.     

Fat Level and Freezing Temperature Affect Sensory, Shear, Cooking and Compositional Properties of Ground Beef Patties

Experiments were conducted to determine effects of two targeted fat levels (6, 20%) and two freezing temperatures (?43, ?20°C) on sensory, shear, cooking and compositional properties of beef patties. Select grade beef rounds (IMPS 161) were used as the lean source for patties with U.S. Choice plates as the fat source. The 20% fat formulation had increased beef flavor and initial tenderness (?20°C frozen patties only) scores, but had higher instrumental shear values compared to the 6% fat patties. Freezing patties (especially those of 6% fat) at ?43°C greatly improved sensory and instrumental tenderness. Faster freezing reduced fat retention of 20% fat patties during cooking. Use of Select grade beef rounds coupled with rapid freezing is suggested for producing acceptable low-fat ground beef patties.