Effect of water,fat, and salt contents on heating uniformity and color of ground beef subjected to radio frequency thawing process

The comminuted meat products are popular and important in the global market. Radio frequency (RF) heating has been proposed as a new alternative method for thawing bulk frozen comminuted meat products with the main advantages of rapid and volumetric heating. However, the temperature non-uniformity is the main obstacle for its industrial applications. In the present study, effects of the level of added water (15–25%), fat (15–25%) and salt (0.1–1.0%) on the heating uniformity and color of ground beef were investigated using a 6 kW 27.12 MHz RF system during thawing process. The results showed that added water had a negative impact on the RF heating uniformity, and a positive impact on beef color. Fat had a major negative effect on the RF heating uniformity and a positive impact on the lightness of the beef sample. The high salt content had a positive influence on the RF heating uniformity, and a significant negative effect on L* value of beef samples. The results may provide some potential methods to improve the RF heating uniformity and quality of food during RF thawing processing.     

二次杀菌时间对猪肉糜持水性的影响

测定猪肉糜二次杀菌前后的蒸煮损失、质构特性以及自旋-自旋弛豫时间,研究85℃条件下二次杀菌时间(0、5、10、15、20、25 min)对猪肉糜持水性的影响。结果表明:二次杀菌导致蒸煮损失率显著增加(P0.05),当杀菌时间超过15 min时,质构特性参数值显著降低(P0.05),不易流动水相对含量显著(P0.05)降低,而自由水相对含量则显著(P0.05)升高。说明二次杀菌时间会影响肉糜中蛋白质的保油保水性,进而影响肉糜制品的质构特性。     

不同热处理方式对牛肉嫩度和挥发性风味物质的影响

为明确不同热处理方式对牛肉品质特性的影响,分别采用常规卤煮、微波和超声辅助卤煮等方式加工牛肉,对加热过程中（5、15、25、35 min）牛肉样品的水分含量、持水力、剪切力、质构特性、微观结构、挥发性风味及感官品质进行测定与分析。结果表明,经水浴加热5 min（W₅）的牛肉样品中的水分含量最高（62.9%）,而微波加热15 min（M₁₅）样品的持水力高达91.8%,其剪切力、硬度和咀嚼性较低,而弹性值最高（3.94 mJ）。微观结构显示,经微波加热15 min（M₁₅）和超声波辅助加热25 min（U₂₅）的牛肉肌纤维结构较为松散,与质构特性结果对应。经不同热处理方式加工后的牛肉中共检测出98种挥发性风味物质,其中壬醛、桉叶油醇、芳樟醇、丁香酚和茴香脑等阈值较低,为主要呈味物质。主成分分析（PCA）显示,不同热处理方式可显著改变牛肉的特征风味,其中W₅、W₁₅（水浴加热15 min）、M₅（微波加热5 min）、U₅（超声波辅助加热5 min）的主要挥发性风味物质相似,M₁₅、U₁₅（超声波辅助加热15 min）和W₂₅（水浴加热25 min）样品的主要挥发性风味物质相似。进一步结合感官评分,可知微波卤煮15 min后的牛肉品质最佳。     

Effect of radio frequency (RF) heating on the texture,colour and sensory properties of a comminuted pork meat product

Radio frequency (RF) cooking is a form of dielectric heating in which products are heated by subjecting them to an alternating electromagnetic field between two parallel electrodes. Although similar in some respects to Microwave heating, RF has been proposed to be more suitable for industrial heating of meats because of the greater penetration depths possible with this technology. In this study an RF cooking protocol was developed and its effect on selected quality attributes of pork based white pudding was examined. Whilst cooking of the product in air proved unfeasible due to arcing, use of a polyethylene cell with circulating hot water (80 °C) facilitated successful heating of the product. Application of RF using an optimised cooking protocol (RF power = 450 W, cell volume = 500 ml and continuous circulation) resulted in a mean end-point temperature of 73 °C after 7 min 40 s. Similar mean end-point temperatures in water bath and steam oven heated products were achieved after 29 and 33 min, respectively. A factorial experiment was conducted to assess selected quality attributes of the cooked puddings. Results show that RF heated puddings were not significantly different (P > 0.05) from water bath and steam oven heated products with regard to instrumental colour, instrumental texture (Kramer shear and texture profile analysis) and expressible fluid. Furthermore, results of a sensory similarity test involving 60 panellists indicated that panellists were not able to detect differences between puddings cooked by RF and conventional methods. Overall this suggests that RF heating technology could have potential in pasteurisation of meat products though further work is needed to verify this.     

Factors affecting the water holding capacity of red meat products: a review of recent research advances

The water holding capacity of meat products is a very important quality attribute which has an influence on product yield, which in turn has economic implications, but is also important in terms of eating quality. A number of pre-and post-mortem factors influence the water holding capacity (WHC) of meat. During the growth and development of meat animals, genotype and animal diet are important due to their direct influence on muscle characteristics. In the immediate pre-slaughter period, stresses on the animal such as fasting, and different stunning methods are likely to influence meat WHC. In the post-slaughter period chilling, ageing, injecting non-meat ingredients, as well as tumbling have important influences on WHC. Furthermore, cooking and cooling procedures for the final meat products can also affect the WHC of the product, in particular the cooking and the cooling methods, the heating and the cooling rate, the cooking temperature, and the endpoint temperature. This paper provides an overview of recent research on important intrinsic and extrinsic factors that affect the WHC of beef, pork, and lamb products, and reveals explanations and solutions to some of the critical problems related to WHC and product quality.     

Meat cooking shrinkage: Measurement of a new meat quality parameter

Chemical, physical and sensory aspects of quality were compared on encased rolls (1kg) prepared from single muscle beef (biceps femoris) cooked in a steam oven (80°C) or by radio frequency (RF) heating (500W, 27.12MHz) under recirculating water at 80°C. The RF protocol reduced cooking times to 23 and 31% of steam cooking times, respectively, in non-injected meat (PG1) and in rolls prepared with curing brines possessing similar dielectric properties (PG2-4). Compared to steam heating, cooking yields were significantly higher (P<0.05) and instrumental texture measurements related to toughness significantly lower (P<0.05) for RF cooked PG1 rolls and for meat injected with brines containing water binding dielectrically inactive additives (PG4) but not for brined rolls lacking the latter ingredients (PG2 and PG3). Participants in a 50 member untrained sensory panel were unable to detect texture differences which had been indicated by instrumental analysis for PG1 and PG4.     

An examination of factors affecting radio frequency heating of an encased meat emulsion

The potential of radiofrequency (RF) heating for rapid cooking of a cased comminuted meat emulsion (white pudding) to a pasteurisation temperature of 73°C was examined. Immersion of the product in water was essential in order to prevent thermal damage to the casings by electrical arcing effects during heating. Using a polyethylene heating cell with non-circulating water the applied RF power, primary electrode distance as well as the mineral content, temperature and volume of the surrounding water all influenced the efficiency of the RF heating. Under optimised conditions maximum/minimum temperature gradients (ΔT) across the products in excess of 15°C were observed. These could be reduced to around 6°C by heating the white puddings in a cell operating with recirculating hot water (80°C). Using an oven power output of 450W a 4.3-fold reduction in cooking time compared to conventional steam oven cooking could be achieved.     

增稠剂提高牛肉持水性的配方研究

肉的持水性指肉在冻结、冷藏、解冻、腌制、绞碎、斩拌、加热等加工处理过程中肉中的水分以及添加到肉中的水分的保持能力。肉的持水性直接关系到肉制品的质地、嫩度、切片性、弹性感,出品率等项质量指标和经济指标。为研究提高肉及肉制品的持水性,本文通过添加不同增稠剂(黄原胶、海藻酸钠、卡拉胶)对离心法测定牛肉持水性的影响,以单因素试验确定最佳添加量,并进行正交试验。确定显著提高牛肉持水性的最佳组合添加量为黄原胶0.2%,海藻酸钠0.2%,卡拉胶0.3%。     

STRESS RELAXATION TEST CONDITIONS FOR MEAT PRODUCTS TO MEASURE VISCOELASTICITY

The effects of various test parameters on stress relaxation analysis measuring viscoelastic properties of beef products, and the suitability of different models to describe that test data were investigated. Three types of processed meat products were evaluated: finely comminuted (frankfurter), ground beef (salami), and whole muscle (corned beef). Cylindrical specimens of meat products, 10, 15 or 20 mm in diameter and 10 mm in length were compressed to 10%, 20% or 30% of their original height for 9 min. The data were fitted using the Maxwell model with two elements and other available models in the literature. Stress was calculated by dividing the force by initial cross sectional area of the sample, and modulus by dividing stress by strain. Both sample size and compression ratio affected model parameters. A diameter to length ratio (D/L) of 1.5 and any compression ration were suitable for the whole muscle product; D/L of 1.5 and 10% or lower compression for ground beef; and D/L of 2 and 10% or lower compression ratio for finely comminuted products were the suitable test conditions.     

Efficacy of radio frequency cooking in the reduction of Escherichia coli and shelf stability of ground beef

The effectiveness of radio frequency (RF) cooking on the inactivation of Escherichia coli in ground beef and its effect on the shelf stability of ground beef were investigated with a comparison to hot water-bath cooking. E. coli K12 was used as a target bacterium instead of E. coli O157:H7. The ground beef samples inoculated with E. coli K12 (ampr) were heated until the centre temperature of each sample reached 72 degrees C. These samples were then stored at 4 degrees C for up to 30 days. The enumeration of E. coli K12, background E. coli and coliform counts in ground beef samples was carried out for shelf-life study. Although both methods significantly reduced E. coli K12 (ampr), E. coli and coliform counts and extended the shelf-life, RF cooking had a shorter cooking time, and more uniform heating. Thus, RF cooking of meat has a high potential as a substitute for the hot water-bath cooking.     

Visual color and doneness indicators and the incidence of premature brown color in beef patties cooked to four end point temperatures

An interlaboratory study was undertaken to assess the frequency that cooked color of ground beef patties appeared brown at internal temperatures of 52.7 degrees C (135 degrees F), 65.6 degrees C (150 degrees F), 71.1 degrees C (160 degrees F), and 79.4 degrees C (175 degrees F). In general, as internal cooked temperature of the patties increased, the following results were observed in the patties: (i) more brown meat color, (ii) less pink or red juice color, and (iii) more cooked texture. However, brown meat color occurred prematurely at the two lower internal temperatures (57.2 degrees C/135 degrees F and 65.6 degrees C/150 degrees F) that are insufficient to eliminate foodborne pathogens without holding times. The common consumer practice of freezing bulk ground beef, followed by overnight thawing in a refrigerator, led to substantial premature brown color in patties cooked from this product. In addition, at 71.1 degrees C (160 degrees F), recognized to be the lowest temperature for cooking ground beef safely in the home, meat color, juice color, and texture appearance were not fully apparent as doneness indicators. In fact, at no temperature studied did 100% of the patties appear done when evaluated by the criteria of no red or pink in the meat, no red or pink in the juices, or by texture appearance. Patties in this study were evaluated under a set protocol for forming the products, cooking, and viewing under the same lighting conditions. Other preparation conditions are possible and may produce different results. Thus, temperature to which patties have been cooked cannot be judged by color and appearance. This study provided the evidence to support the message to consumers regarding cooking of beef patties of "use an accurate food thermometer and cook beef patties to 160 degrees F (71.1 degrees C)" in place of messages based on consumer judgment of cooked color.     

Presalting effects on water retention of pork and beef batters

Presalting effects were studied by measuring cooking loss as a function of chopping time for pork and beef batters. Presalting (ground meat/salt/water = 100/3/20, by weight, 24h) as compared with direct salting in the chopper, substantially reduced the cooking loss of pork batters, but only when the batters were relatively coarsely chopped. With more extensive chopping (exceeding 10–15 min at low chopper speed) no presalting effects were found, indicating that salt diffusion, protein dissolution and myofibril swelling were completed also in control batters salted in the chopper. Presalting of beef had a much weaker, although similar, effect on water retention properties.The practical implications are that presalting may help in reducing cooking loss of coarsely comminuted sausages, particularly pork products. Presalting, however, has no beneficial effect on finely comminuted, bowlchopper-produced sausages.     

圆苞车前子壳粉的添加对肉饼品质的影响

为探究不同破碎工艺对低脂肉糜蛋白质性质和食用品质的影响,在打浆机和斩拌机上,采用不同刀具（钝刀和利刀）制备肉糜,测定肉糜的pH、盐溶性蛋白质含量、蛋白质二级结构、粒径分布、色泽、流变特性和肉糜凝胶的蒸煮损失、持水力、质构特性、微观结构。结果表明：4种破碎工艺对肌肉纤维的破碎程度不同,使低脂肉糜及所形成的凝胶呈现不同性质。与打浆机相比,斩拌机处理的低脂肉糜在温度扫描中拥有更高的G'值。钝刀打浆处理的低脂肉糜在频率扫描中拥有最低的粘度,呈现较差的稳定性。斩拌机高强度的切割作用使得破碎的肉糜的终点温度更低、颗粒粒径更小,煮制形成低脂肉糜凝胶的持水力更高。与其他3种工艺相比,钝刀斩拌低脂肉糜有最高的红度值、pH、盐溶性蛋白质含量和β折叠的相对含量,分别为15.95、6.66、77.05 mg/mL、43.71%,所形成低脂肉糜凝胶的蒸煮损失最低和硬度、胶黏性、咀嚼性、感官评分最高,分别为17.48%、4147.72 g、2883.35、2496.02 g,这可能归因于该处理对肌肉的适度破碎所形成的低脂肉糜凝胶具有更加紧密的微观结构。因此,钝刀斩拌工艺适用于低脂肉糜的破碎生产,可提高其盐溶性蛋白质含量、β折叠相对含量、红度、持水力和质构特性。     

鸡蛋腌制对3种烤肉饼食用品质的影响

为系统分析传统中式菜肴烹调过程中鸡蛋腌制处理对不同肉类食用品质的影响,分别选用全蛋腌制或蛋清腌制、不同蛋清添加量腌制处理,分析其对猪肉饼、牛肉饼和羊肉饼食用品质的影响。结果表明,在添加量为10%、腌制时间为30 min时,蛋清腌制显著增加猪肉饼和羊肉饼的水分含量（P<0.05）,显著降低两种肉饼的烤制损失率、剪切力值和硬度等（P<0.05）,有效改善猪肉饼和羊肉饼的食用品质,而牛肉饼则适合选用全蛋腌制处理,能在一定程度上改善其食用品质;不同蛋清添加量对3种肉饼的食用品质有不同影响,腌制时间为30 min时,猪肉饼和羊肉饼宜选择10%蛋清添加量,牛肉饼宜选择5%蛋清添加量,此时肉饼的保水性较好,嫩度、色泽和质构特性较优,适合作为日常烹饪过程中蛋清腌制的最佳添加量推广使用,本研究为传统中式菜肴中畜肉烹饪前鸡蛋腌制的条件提供了理论支持。     

Fat reduction in comminuted meat products-effects of beef fat, regular and pre-emulsified canola oil

The effects of fat reduction (25.0%, 17.5%, and 10.0%) and substituting beef fat with canola oil or pre-emulsified canola oil (using soy protein isolate, sodium caseinate or whey protein isolate) on cooking loss, texture and color of comminuted meat products were investigated. Reducing fat from 25 to 10% increased cooking loss and decreased hardness. Canola oil or pre-emulsified treatments showed a positive effect on improving yield and restoring textural parameters. Using sodium caseinate to pre-emulsify the oil resulted in the highest hardness value. Cohesiveness was affected by fat type and level. The color of reduced fat meat batters was darker for all, except the beef fat treatments. Using canola oil or pre-emulsified oil resulted in a significant reduction in redness. The results show that pre-emulsification can offset some of the changes in reduced fat meat products when more water is used to substitute for the fat and that pre-emulsification can also help to produce a more stable meat matrix.     

Effect of radio frequency cooking on the texture, colour and sensory properties of a large diameter comminuted meat product

Radio frequency (RF) cooking is a form of dielectric heating similar to microwave heating. In this study an optimised cooking protocol was developed for pasteurising 1 kg cased meat emulsion samples, which were immersed in 80 °C circulating water during cooking. Subsequently, selected quality attributes of RF pasteurised samples were compared to steam pasteurised samples, by instrumental and sensory methods. Instrumental assessments show that RF heated meat batters had a greater ability to hold water, were significantly harder, chewier and gummier (P<0.001), while having less cook colour development than their steam cooked counterparts. Differences were also detected by sensory methods. In conclusion, while differences were detected, it is possible that these could be eliminated by adjusting the cooking protocol to produce similar cook values in RF samples to those in products cooked by steam.     

Effects of transport time and rest period on the quality of electrically stimulated male cattle carcasses

Ground, pre-salted, pre-rigor semimembranosus muscles of beef were subjected to three treatments A=rapid carbon dioxide (CO(2)) chilling, B=slow CO(2) chilling and C=air chilling, and compared to a control D=slow air chilling of muscles, which were subsequently ground and salted post-rigor. Meat of the pre-rigor treatments A, B and C had higher pH values during processing, lower cooking loss, firmer texture and a lighter yellowish external colour of cooked patties than the post-rigor control D (p<0.05). The two CO(2) chilling regimes A and B had no detrimental effects on the functional properties of the pre-rigor meat. Sarcomere lengths did not differ in meat of the four treatments (p>0.05), indicating that early pre-salting protected the meat from cold shortening during rapid temperature decline. A process combination of grinding, followed by immediate pre-salting and CO(2) chilling within 312h post-mortem of non-stimulated beef muscles is likely to yield superior binding properties of cooked patties and similar ground beef products.     

Effects of cooking method, reheating, holding time, and holding temperature on beef longissimus lumborum and biceps femoris tenderness

Effects of cooking method, holding temperature, holding time, and reheating on Warner-Bratzler peak shear force (WBPSF); Warner-Bratzler myofibrillar force (WBM-F), Warner-Bratzler connective tissue force (WBC-F) and cooking loss were investigated. Two muscles (longissimus lumborum and biceps femoris) from USDA Choice beef carcasses were used. Water-bath cooking resulted in higher WBPSF, WBM-F, and WBC-F than belt-grill cooking for longissimus lumborum. The biceps femoris muscle tenderness improved more with holding time after cooking on a belt than the longissimus lumborum due to its higher collagen content. Cooking biceps femoris steaks to 54?°C by a belt grill and holding them at 57?°C in a water bath for 15 min and subsequent reheating to 70?°C (best treatment combination) produced a 25% reduction in WBPSF, a 37% reduction in WBC-F, and a 12% reduction in WBM-F as compared to the control (cooking steaks directly to 70?°C without holding). Water-bath cooking resulted in lower WBPSF than belt-grill cooking for biceps femoris without any holding time, but further tenderization did not occur with holding. Water-bath cooking resulted in higher cooking losses than belt-grill cooking for both muscles.     

IDENTIFICATION OF NONMEAT INGREDIENTS FOR INCREASING FAT HOLDING CAPACITY DURING HEATING OF GROUND BEEF

Eleven starch‐, fiber‐, and protein‐based ingredients were evaluated for their fat holding capacity (FHC) in ground beef during heating. A test for FHC was developed where 20 g samples of 20% fat ground beef containing a 10% (wt/wt) addition of the selected ingredient were heated using low power microwave energy until internal temperatures were ～90C. Volumes of cooked‐out water and fat were measured. FHC was determined based on the amount of fat released during cooking. High fiber ingredients retained more water and also had the highest FHC. Ground beef mixed with inner pea fiber retained the most fat, while the all‐beef controls retained the least fat. Inner pea fiber appears to be a useful ingredient in the development of food products required to retain maximum amounts of fat during heating.     

Fat content has a significant impact on protein oxidation occurred during frozen storage of beef patties

This study examined the relationship between protein and lipid oxidation and the impairment of water holding capacity (WHC), colour and texture after frozen storage (20 weeks/−18 °C) and subsequent processing (cooking, chilled storage) of beef patties with increasing fat content (3, 20 and 35%). Various manifestations of protein oxidation were found to occur during frozen storage and processing of patties including, loss of tryptophan fluorescence, carbonylation and formation of Schiff bases structures (SB). Patties with higher fat content underwent the more intense protein oxidation as assessed by formation of protein carbonyls and SB, highlighting the timely interaction between proteins and oxidizing lipids. Protein oxidation occurred concomitantly with loss of WHC and discolouration of beef patties. Mechanisms and consequences of the chemical modifications induced by oxidative stress in meat proteins are thoroughly discussed.