Temperature evolution and mass losses during immersion vacuum cooling of cooked beef joints - A finite difference model

A finite difference model was developed to describe and predict the temperature and mass loss evolution in reconstructed beef joints during immersion vacuum cooling. Fast cooling is obtained within beef pores and at beef surface when evaporation in the surrounding liquid is high. The cooling rate diminishes as the vacuum chamber pressure stabilizes and the liquid temperature reaches its lower value. The maximum deviation between measured and calculated temperatures was within 5°C for the beef (core and surface) and within 7°C for the surrounding liquid (measured at the bottom of the container). Absolute differences between predicted and experimental mass losses for the liquid and beef sample were around 2% and 1%, respectively. Mass losses are higher during the first period when evaporation is the main mode of heat transfer. Mechanical agitation in the surrounding liquid is suggested as a way to further reduce cooling times and to prevent uneven cooling.     

Simulation and experimental validation of simultaneous heat and mass transfer for cooking process of Mortadella Bologna PGI

In this study, Protected Geographical Indication (PGI) Mortadella Bologna cooking process was investigated for heat and mass transfer. Apparent mass and heat transfer coefficient functions as well as apparent thermal diffusivity and mass diffusion coefficients were experimentally estimated. These thermo‐physical properties were used to develop a mathematical model for the simulation of simultaneous heat and mass transfer during Mortadella Bologna PGI cooking. The developed method was successfully validated for both heat and mass transfer by means of experimental cooking tests: maximum errors of about 3.5% and 4% were found for final product temperature and cooking time experimentally obtained respectively. Simulated weight loss values were also found not to differ significantly from those experimentally obtained. In addition, the developed model was successfully validated during a Mortadella cooking process carried out in an industrial plant proposing itself as a predictive tool to forecast and optimise cooking time and weight loss of this type of meat product. The proposed approach may be also used to design air cooking processes of other food products.     

Prediction of cooking times and weight losses during meat roasting

In this work, a meat oven cooking model is developed, and its ability to predict three main process variables – evaporative loss, dripping loss and cooking time – is evaluated. Heat transfer is modelled by Fourier’s law, while the internal moisture content variation is modelled as a function of water demand, which depends on the water holding capacity of beef. Experimental cooking of semitendinosus muscle samples was carried out in a convective oven to obtain general information about the process and to assess the model accuracy. Simulations were done by means of the finite element method, using three-dimensional irregular geometries as simulation domains. The model predictions were in good agreement with the experimental ones; the average absolute relative error was 3.91% for cooking time prediction, and 7.96% for total weight loss prediction.     

Effect of cooking and cooling method on the processing times, mass losses and bacterial condition of large meat Joints

This study compares the heating and cooling times of and mass losses from meat joints in three systems: convective air, water immersion and pressure/vacuum. Cooling times were compared with the UK Department of Health (DoH, 1989) guidelines which state that joints should be cooled to 10°C or below in less than 150 min.
Five types of joint were used: 50-mm thick (0.94kg) slabs of beef m. semitendinosus, 2.7kg rolled beef forequarter and silverside, 6.4kg rolled turkey and 7.1kg boned-out ham joints. Six replicates of all joints were cooked from 5 to 75°C (beef), 80°C (ham) or 85°C (turkey) and then cooled to a maximum internal temperature of 10°C.
Average cooking times for convection, immersion and pressure were 263, 278 and 135 min, respectively. Average cooling times for convection, immersion and vacuum were 433, 298 and 50 min, respectively. Vacuum cooling times did not depend on joint size but may have been affected by porosity of the meat. The DoH guidelines could be achieved by immersion or vacuum methods when cooling the small beef slabs but only vacuum cooling was sufficiently rapid when cooling the larger joints.
Mass losses due to pressure cooking (mean 37.4%) were greater than those during convection heating (28.9%). Vacuum cooling resulted in an average mass loss of 8.2% but losses were smaller after convection cooling (2.5%). Average total viable counts (log10 no. of bacteria cm⁻²) after processing and 12h storage were 1.0 at both the surface and interior.     

Microstructure and protein digestibility of beef: The effect of cooking conditions as used in stews and curries

Beef meat was cooked at 373 K for 10 and 30 min to investigate the effect of the cooking conditions generally used during beef stew and curry preparation on protein digestibility. The cooked meats, along with a raw control, were digested using an in vitro digestion model to simulate gastric and small-intestinal conditions. Samples taken at different digestion times were analyzed using SDS-PAGE, RP-HPLC, ninhydrin assays for amino N and transmission electron microscopy. Simulated gastric conditions quickly led to the loss of basic sarcomere structure in raw meat myofibrils whereas the sarcomere structure of the compact cooked meat myofibrils remained intact after 30 min of gastric digestion. Prolonged cooking of meat (30 min) resulted in incomplete digestion of small MW (<10 kDa) peptides, as observed from SDS-PAGE. This agreed with the amount of ninhydrin-reactive amino N released during digestion, which decreased with an increase in cooking time. The RP-HPLC peak areas of the major identified amino acids (tryptophan, tyrosine and phenylalanine) also decreased with an increase in cooking time. This suggested the formation of “limit peptides” during prolonged cooking of beef, which were not further broken down into free amino acids by digestive enzymes and therefore might not be bioavailable.     

MODELING MICROWAVE COOKING of COCKTAIL SHRIMP

A mathematical model for microwave cooking of cocktail shrimp was developed. the model included heat and mass transfer and microbial inactivation kinetics. A simple 2 dimensional cylindrical slab geometry was used and model equations were solved using the finite difference method. the model predictions on temperature and mass loss were in good agreement with the observed data. Temperature predictions were within ± 6C and mass predictions were within ± 2 g of the observed data.     

黑切牛肉贮藏过程中活性氧相对含量变化及其与肉品质指标相关性分析

活性氧在宰后肉品质形成过程中起重要作用,研究活性氧在黑切(dark, firm and dry,DFD)牛肉中对肉品质变化的影响。以黑切牛肉(pH_{24 h}>6.2)为研究对象,取宰后4℃排酸24 h牛肉,4℃贮藏,在贮藏1、24、72、120 h分别测定活性氧相对含量、色差值、pH值、蒸煮损失率、滴水损失率、羰基含量及巯基含量,并进行相关性分析。结果表明：贮藏期间黑切牛肉的pH值大于6.5,显著高于正常牛肉;活性氧相对含量在贮藏期间呈升高趋势,一直高于60 L/(min·mg),贮藏72、120 h高于正常牛肉;红度值在贮藏期间均在4.47以下,低于正常牛肉;滴水损失率低于8.90%,蒸煮损失率低于28.10%,均低于正常牛肉;羰基含量高于2.80 nmol/mg、巯基含量高于37.16 nmol/mg,羰基含量在贮藏72、120 h高于正常牛肉,巯基含量贮藏期间低于正常牛肉;相关性分析表明,黑切牛肉中活性氧与肌肉蛋白质氧化指标羰基含量、巯基含量显著相关。活性氧与黑切牛肉成熟过程中肉品质形成密切相关,其可能是调控黑切牛肉品质变化的重要因子。     

Effects of Electrical Stimulation, Boning Temperature, Formulation and Rate of Freezing on Sensory, Cooking, Chemical and Physical Properties of Ground Beef Patties

The effects of electrical stimulation vs nonstimulation, temperature of boning (hot vs cold), formulation (USDA Choice chucks with USDA Choice plates vs imported cow lean with USDA Choice plates) and rate of freezing (fast = -50°C vs slow = -20°C) were determined on sensory, cooking, chemical, and physical properties of ground beef patties. Sensory panel ratings for tenderness were highest in patties from formulations processed with either nonstimulated beef, hot-boned beef or Choice chucks. The substitution of imported cow lean for Choice chucks generally reduced cooking losses and changes in patty height during cooking. Fat losses during cooking were higher in patties made from electrically stimulated than nonstimulated beef, while moisture losses during cooking were greater for patties from nonstimulated than stimulated beef. Of the factors involved in this study, hot boning produced the most beneficial results in beef patties. Boneless chucks and plates from electrically stimualted Choice carcasses appear to be suitable raw materials for production of ground beef patties.     

电子鼻快速检测不同煮制时间的酱牛肉风味

利用电子鼻研究煮制过程中的酱牛肉挥发性风味变化,分析其动态变化规律。利用主成分分析法、传感器的载荷分析法和线性判别式分析法对不同煮制时间的酱牛肉进行归类分析。结果表明:不同煮制时间对酱牛肉的风味有较大影响,煮制4 h获得最具特色的酱牛肉风味。     

Characteristics of restructured beef steak with different proportions of walnut during frozen storage

Physicochemical (thawing loss, cooking loss, surface shrinkage, texture, colour and lipid oxidation) and sensory properties of restructured beef steak with different levels of added walnut (0%, 10% and 20%) were determined at various times during frozen storage up to 128 days. Cooking loss (CL), Kramer shear force (KSF) and binding strength (BS) of restructured beef decreased (P<0.05) as the proportion of walnut increased. Walnut enhanced (P<0.05) lightness and yellowness and reduced (P<0.05) redness. Frozen storage did not affect (P>0.05) CL, KSF and BS of restructured beef steak. Redness decreased (P<0.05) over storage for all samples. Lipid oxidation of restructured beef steak containing walnut was not a limiting factor for frozen stability of meat products. Frozen storage had no effect (P>0.05) on the sensory quality of restructured beef steak.     

EFFECT of DIFFERENT TEMPERATURE CONTROL METHODS ON HEATING TIME and CERTAIN QUALITY PARAMETERS of OVEN-ROASTED BEEF

Four different methods of oven roasting beef were studied. Twelve semi-tendinosus muscles were transversely divided, and the 24 subsamples were allocated to 4 cooking methods: High temperature roasting (HTR) with a constant oven temperature of 170C; low temperature roasting (LTR) with a constant oven temperature of 120C; maximum temperature roasting (MTR) with maximally 70C 1 cm below the roast surface and temperature difference roasting (TDR) with constantly 50C between the oven and 1 cm below the roast surface. Quality parameters measured were cooking loss, Warner-Bratzler shear parameters and taste panel ratings. Mean heating times of HTR, LTR, MTR and TDR were 69, 100, 79 and 157 min, respectively. Most of the quality parameters by HTR were significantly poorer as compared with the other methods, while differences between LTR, MTR and TDR were small. Surface heat transfer coefficient was estimated as 14.1 W/m²C. Heating times were predicted with a maximum deviation of 10%.     

Kinetic analysis of cooking losses from beef and other animal muscles heated in a water bath--effect of sample dimensions and prior freezing and ageing

Cooking loss kinetics were measured on cubes and parallelepipeds of beef Semimembranosus muscle ranging from 1 cm × 1 cm × 1 cm to 7 cm × 7 cm × 28 cm in size. The samples were water bath-heated at three different temperatures, i.e. 50°C, 70°C and 90°C, and for five different times. Temperatures were simulated to help interpret the results. Pre-freezing the sample, difference in ageing time, and in muscle fiber orientation had little influence on cooking losses. At longer treatment times, the effects of sample size disappeared and cooking losses depended only on the temperature. A selection of the tests was repeated on four other beef muscles and on veal, horse and lamb Semimembranosus muscle. Kinetics followed similar curves in all cases but resulted in different final water contents. The shape of the kinetics curves suggests first-order kinetics.     

Modeling cooking of chicken meat in industrial tunnel ovens with the Flory–Rehner theory

In this paper we present a numerical model describing the heat and mass transport during the cooking of chicken meat in industrial tunnels. The mass transport is driven by gradients in the swelling pressure, which is described by the Flory–Rehner theory, which relates to the water holding capacity (WHC). For cooking temperatures up to boiling point and practical relevant cooking times, the model renders good prediction of heat and mass transport and the total loss of moisture. We have shown that for cooking temperatures above boiling point, the model has to be extended with the dynamic growth of capillary water (drip) channels. Furthermore, we discuss that the Flory–Rehner theory provides the proper physical basis for describing the change of the WHC by a wide variety of factors like salt and pH.     

不同烹饪方式对骨膳食营养成分保留度的比较分析

为了分析不同烹饪方式对骨膳食营养成分保留度的影响,研究选取从某大型生鲜超市采购回来的带肉牛骨作为研究对象,分别选取油煎、低温烹饪和水煮三种不同的烹饪方式烹调牛肉,对比了不同烹饪方法烹调后牛肉质量损失率、蛋白质损失率、脂肪损失率、卵磷脂损失率、钙损失率情况以及感官品质评分,对比分析结果显示,低温烹煮后牛肉质量损失率最低,仅为32.74%;牛肉中的蛋白质损失率仅为9.78%;牛肉中的脂肪损失率相对较低,为47.82%左右;同时牛肉中卵磷脂成分保留度较高,钙损失率最低;同时,采用低温烹饪的方法加热牛肉无论在色泽,还是在味道和气味等感官品质评分均高于油煎和水煮,说明低温烹饪不仅能够有效提高骨膳食营养成分保留度,而且具有较高的感官品质评分。     

减盐火锅底料对牛肉食用品质及钠、钾含量的影响

以牛肉（牛里脊肉）为原料,在不同比例NaCl和KCl组成减盐配方的火锅底料中涮制不同时间,比较KCl替代比例及涮制时间对牛肉感官评价、剪切力、蒸煮损失率的影响,并探究牛肉在减盐火锅底料中涮制前后盐含量、钠含量与钾含量的变化规律。结果表明：牛肉在NaCl、KCl质量比7∶3的减盐火锅底料中涮制各时间点感官评分均最高,在不同比例NaCl和KCl组成的减盐火锅底料中涮制,剪切力均随涮制时间的延长而增加,在涮制160 s后增加最显著;牛肉盐含量与钠、钾含量均随涮制时间的延长而显著增加,相同涮制时间下牛肉钠含量随减盐配方中KCl替代比例的升高而降低,且钠含量降低比例与KCl替代比例接近。减盐火锅底料能在不影响牛肉风味与食用品质的前提下,降低火锅钠摄入量30%左右,推荐减盐火锅底料KCl替代比例为30%,推荐牛肉涮制时间为120 s。     

MATHEMATICAL MODEL TO PREDICT YIELD LOSS OF MEDIUM AND LARGE TIGER SHRIMP (PENAEUS MONODON) DURING COOKING

Cooking causes moisture loss and reduces the yield of shrimp. This can be affected by its size, cooking temperature and time. A finite difference mathematical model to predict temperature distribution during heating/cooling of shrimp was modified to enable prediction of yield loss. The relationship between cooking temperature, time and yield loss was determined by isothermal experiments. For medium and large Tiger shrimp (Penaeus monodon), data were fitted into the following form: % Yield Loss = a + b*T + c *T²+ d*t²+ e*t + f*T*t where T is temperature and t is time. These equations were used in the model. Each volume element in the model was allowed to have its own yield loss; and overall yield loss was found by calculating mass average values. Experiments were conducted to cook Tiger shrimp under regular conditions and determine its yield loss, and the predictions of the model were compared with experimental data. Close agreement was obtained. This model can be used to predict yield losses during cooking of shrimp.     

Cooking loss in Beef. The effect of cold shortening,searing and rate of heating; time course and histology of changes during cooking

Techniques developed earlier to measure cooking loss in beef sternomandibularis and rectus abdominis muscles under defined conditions, have here been extended to other factors affecting cooking loss. Cold shortening of the muscle has no effect. Searing of the ends before cooking causes a slight increase in loss. In samples cooked for varying times at 80 ºC, cooking loss rises gradually up to 2h, while cooking shortening and shear force reach a maximum much more quickly. Colour changes are described in meat cooked for various times, then cut and exposed to air. Slow cooking gives higher cooking losses than fast, but a lower shear force. Histological studies have shown that in frozen sections maintained in aqueous media the annular shrinkage space is small and does not vary significantly between cooking treatments. The dehydration involved in paraffin sections exaggerate the shrinkage, although these sections show best the fused and apparently intact sarcolemmas. The electron microscope, however, reveals that there are many punctures in the membranes.     

夏南牛不同部位加工特性及牛肉干加工适宜性评价

夏南牛是我国自主培育的第一个专用肉牛新品种，为促进夏南牛肉及其深加工产品的工业化和科学化发展，本实验研究不同部位牛肉的理化指标和加工品质指标的差异，并评价其牛肉干加工适宜性。选取并测定20 个原料肉理化指标和9 个牛肉干产品加工品质指标，利用相关性分析和主成分分析筛选关键指标，并建立评估方程。结果表明：不同部位牛肉理化特性存在明显差异。臀肉的水分质量分数（75.47%）和蛋白质量分数（21.51%）最高，脂肪质量分数（2.39%）最低（P＜0.05），凝胶和乳化性能较好。肩肉的脂肪质量分数最高（8.69%），质构特性较好，剪切力较小。牛腱的解冻损失率（1.81%）和蒸煮损失率（24.08%）最低，剪切力最小（4.99 kg）。霖肉的解冻损失率（6.36%）和蒸煮损失率（34.22%）最大。2）牛肉干加工适宜性综合评价模型为Y＝0.197 9A＋0.026 0B＋0.312 8C＋0.218 8D＋0.245 5E（A、B、C、D和E分别代表a*、硬度、羟脯氨酸含量、蒸煮损失率和乳化稳定性）。3）肩肉和黄瓜条适合加工牛肉干，而霖肉和牛腱不适合；4）以感官评价结果为因变量，以综合品质评价结果为自变量，建立回归方程为y＝3.646 5x＋4.556 2（R2＝0.824 2）。综合评价模型可以较好地预测肉干加工适宜性。本研究为夏南牛加工特性补充和更新了必要的参数，此外，还找到了更适合牛肉干加工的部位。     

基于传质动力学的湘味卤牛肉卤制方法比较

为提升湘味卤牛肉卤制效率、品质及原辅料利用率,以牛腿肉为原料,传统卤制（常压,95 ℃）为对照,通过对比不同真空卤制、微压卤制、脉冲卤制条件下的NaCl传质速率、感官品质、质构特性以及牛肉微观结构,优化出最佳卤制工艺。结果表明,最佳卤制工艺为脉冲卤制工艺,条件为:?50 kPa,80 ℃结合+50 kPa,95 ℃,脉冲频次4次,卤制时长2.7 h,此条件下卤牛肉感官评分（89.6分）、传质系数（2.71×10?6 m2/s）,均优于真空卤制最佳条件（?50 kPa,80 ℃）、微压卤制最佳条件（+50 kPa,95 ℃）、传统卤制的感官评分（85.2、86.1、83.6分）、传质系数（1.91×10?6、1.92×10?6、1.64×10?6 m2/s）;脉冲卤制的卤牛肉质构特性有显著提升（P<0.05）,质量变化率显著低于微压卤制与传统卤制（P<0.05）;电镜扫描显示,脉冲卤制对牛肉微观结构影响最小,有利于降低营养流失,提升NaCl传质。脉冲卤制能有效提升湘味卤牛肉卤制效率,缩短卤制时间,减少原辅料损失,提高出品率。     

Effects of different objective functions on optimal decision variables: a study using modified complex method to optimize hamburger cooking

Hamburger patties are prepared from ground beef and cooked to obtain a safe product before consumption. Cooking process eliminates microbial hazards and results in certain quality changes (e.g., cooking loss, textural changes). All these changes can be used as an objective function to achieve an optimum cooking process, but their effects on decision variable (e.g. process temperature profiles) of the optimization should be known. The use of different objective functions (minimization of cooking losses, hardness, chewiness, and shear to work) was compared to see their effects on plate temperature profiles for double-sided contact cooking. Modified Complex Method was applied as the optimization procedure. Lower and higher limits of grill temperatures (177–220°C) were explicit constraints while lethality and temperature at the patties center (F₀⩾15 s; T_c⩾71°C) were implicit constraints. The objective functions and implicit constraints were determined using a previously developed numerical heat transfer simulation model. Constant temperature profiles (decision variables) for different objective functions at different processing times (121 and 130 s) were determined. Same decision variables were found regarding the different objective functions (198.3°C and 184.1°C) for the given processing times.