Effect of rapid and conventional cooling methods on the quality of cooked ham joints

Three cooling regimes, vacuum (VC), blast (BC) and slow cooling (SC), were compared for their effect on cooling rate, weight loss and quality of large cooked ham joints. Vacuum cooling reduced the cooling rate (70-4°C) significantly (P<0.05) in comparison to the other methods; mean cooling times for cooked hams (5-6 kg) were 1.9 h for VC, 11.7 for BC and 14.3 for SC. However, VC gave an increased chill loss (P<0.05) of ca. 11% compared to ca. 4% for the other methods due to evaporative moisture loss. Sensory panels found that VC hams were tougher and less juicy (P<0.05). Shear force measurements and texture profile analysis also showed the vacuum cooling to have a toughening effect on the cooked ham. While vacuum cooling had an adverse effect on quality and yield, it was the only one that conformed to recent safety guidelines for cooked meat joints of a reduction in temperature to 5°C inside 10 h. The cooling conditions used do not reproduce full-scale industrial practice, however, the effects found serve as an indicator of the potential benefits and drawbacks of vacuum cooling for cooked meat joints.     

Effect of tumbling time and cooking temperature on quality attributes of cooked ham

This study evaluates effect of tumbling time and cooking temperature on cooking rate, cooking loss (CL), colour, water activity and water‐holding capacity of cooked restructured ham rolls. In experiment were investigated three tumbling times (2, 4 and 6 h) at constant temperature (+4 °C) and three cooking temperatures (76, 86 and 96 °C). It was observed that CL decreased (P < 0.01) from 5.41% to 3.22% with tumbling time (2 h vs. 6 h) but increased (P < 0.01) from 2.35% to 7.25% along with cooking temperature (76 °C vs. 96 °C). In contrast, pH value increased (P < 0.01) from 6.18 to 6.24 with tumbling time (2 h vs. 6 h) but decreased (P < 0.01) from 6.22 to 6.17 along with cooking temperature (76 °C vs. 96 °C). In addition, high temperature had higher efficiency for thermal lethality than low temperature (F₀ values were 19 and 92 min at 96 and 76 °C, respectively). Intermediate tumbling (4 h) and cooking (86 °C) could be preferential.     

不同冷却方式对熟制馄饨品质的影响

通过真空冷却、鼓风冷却以及自然冷却3种方式对熟制馄饨进行冷却处理,并在4℃的条件下对产品密封储藏,研究随储存时间的延长,3种不同冷却方式处理的馄饨产品品质的变化情况。结果表明:与常规冷却方式相比较,真空冷却的冷却速率高(P<0.05),冷却失重率大(P<0.05);真空冷却的产品L*值偏小,a*值偏大(P<0.05);硬度和咀嚼性较大、弹性较低(P<0.05),但粘结性、黏性、回复性方面3种冷却方式没有显著差异。随着储藏时间的延长,真空冷却能显著降低馄饨产品的菌落总数、TBA值和pH值(P<0.05),减缓产品品质的劣变。     

乳酸钙部分替代氯化钠对西式盐水火腿感官品质的影响

在西式盐水火腿加工中应用乳酸钙部分替代氯化钠,在氯化钠使用总量2%的前提下,按照氯化钠质量的5%、10%、15%、20%设计乳酸钙的替代比,单因素实验观察不同替代比对切片西式盐水火腿色差、质构、水分含量和感官指标的影响。结果发现,适量使用乳酸钙可以显著提高西式盐水火腿的亮度L*值、红度a*值、黄度b*值和硬度;但是当替代比过大时对产品的弹性、内聚性、胶着性、咀嚼性有一定负面影响;适当的使用乳酸钙替代氯化钠对产品感官品质有积极影响,适宜的替代比为10%左右。      

蓝莓对蒸煮火腿中亚硝酸盐和亚硝胺的抑制作用研究

目的研究15种不同品种蓝莓果对肉制品加工过程中亚硝酸盐残留量和亚硝胺生成量的抑制作用。方法 以蒸煮火腿加工工艺为基础,对15种不同品种蓝莓果进行实验,依据GB 5009.33-2010测定肉制品中亚硝酸盐的含量,采气相色谱质谱联用技术(GC-MS)测定肉制品中的8种亚硝胺[N-亚硝基二甲基胺(NDMA)、N-亚硝基甲乙胺(NMEA)、N-亚硝基二乙基胺(NDEA)、N-亚硝基吡咯烷(NPYR)、N-亚硝基二丙基胺(NDPA)、N-亚硝基哌啶(NPIP)、N-亚硝基二丁基胺(NDBA)、N-亚硝基二苯基胺(NDphe A)]。结果 15种蓝莓果对亚硝酸盐的抑制率在6.27%~38.11%之间,平均值为25.17%,对亚硝胺的抑制率在53.64%~71.54%之间,平均值为63.01%。结论 蓝莓果对肉制品加工过程中亚硝酸盐和亚硝胺的含量具有显著抑制作用。     

不同冷却方式对熟制包子品质的影响

包子熟制之后需要冷却然后才能进行包装贮藏,为找到最适合熟制包子的冷却方式,文中通过对产品进行自然冷却、鼓风冷却、真空冷却和混合冷却4种不同的处理,比较其在同一温度下贮藏不同时间的品质变化。结果表明:不同冷却方式对产品保质期有不同影响(P<0.05),混合冷却方式具有取代常规冷却和真空冷却方式的可行性。混合冷却的质量损失明显低于真空冷却而冷却速率显著快于常规冷却方式;在色泽方面混合冷却可以改善真空冷却的颜色较暗这一缺点;在硬度与电子鼻分析方面混合冷却与常规冷却相比有较明显差异(P<0.05),但相对于真空冷却已有提高,在黏聚性、黏性、咀嚼性等方面混合冷却与常规冷却没有显著差异(P>0.05);感官评分的可接受性明显优于真空冷却。在化学指标测定方面:混合冷却与真空冷却对pH值变化的影响较小(P>0.05)并且可以降低包子皮的老化程度;混合冷却与真空冷却均可以显著延缓微生物污染和脂肪氧化程度,从而达到延长食品货架期的目的。     

Influence of NaCl content and cooling rate on outgrowth of Clostridium perfringens spores in cooked ham and beef

The effect of NaCl concentration and cooling rate on the ability of Clostridium perfringens to grow from spore inocula was studied with the use of a process that simulates the industrial cooking and cooling of smoked boneless ham and beef roasts. NaCl was added to ground cooked hams A and B (which were commercially obtained) to obtain levels of 2.4, 3.1, 3.6, and 4.1% (wt/wt) and 2.8, 3.3, 3.8, and 4.3% (wt/wt), respectively, and to raw ground beef to obtain levels of 0, 1, 2, 3, and 4% (wt/wt). Ham C, a specially formulated, commercially prepared product, was supplemented with NaCl to obtain levels of 2.0, 2.5, 3.0, and 3.5%. The samples were inoculated with a three-strain mixture of C. perfringens spores to obtain concentrations of ca. 3 log10 CFU/g. Portions of meat (5 g each) were spread into thin layers (1 to 2 mm) in plastic bags, vacuum packaged, and stored at -40 degrees C. Thawed samples were heated at 75 degrees C for 20 min and subsequently cooled in a programmed water bath from 54.4 to < or = 8.5 degrees C in 15, 18, or 21 h. For the enumeration of C. perfringens, samples were plated on tryptose-sulfite-cycloserine agar and incubated in an anaerobic chamber at 37 degrees C for 48 h. Population densities for cooked ham and beef increased as cooling time increased, and NaCl exerted a strong inhibitory effect on the germination and outgrowth of C. perfringens. For beef, while 3% NaCl completely arrested growth, pathogen numbers increased by > or = 3, 5, and 5 log10 CFU/g in 15, 18, and 21 h, respectively, when the NaCl level was <2%. C. perfringens did not grow during cooling for 15, 18, or 21 h in ham samples containing > or = 3.1% NaCl. Results obtained in this study suggest that a 15-h cooling time for cooked ham, which is normally formulated to contain >2% NaCl, would yield an acceptable product (with an increase of <1 log10 CFU/g in the C. perfringens count); however, for beef containing <2% NaCl, C. perfringens populations may reach levels high enough to cause illness.     

干腌火腿的质量分析及改善方法

干腌火腿是用猪的前、后腿经腌制和发酵等加工步骤制作而成的一种干腌肉制品.随着人们经济水平的提高,生产高质量的干腌火腿已成为市场必需.本文从风味、质地、色泽三个方面分析了干腌火腿的质量及其常见的问题,重点提出了对其质量加以改善的方法.     

不同冷却方式对熟制春卷品质的影响

探索自然冷却、冷风冷却、真空冷却与混合冷却4种冷却方式对熟制春卷品质的影响。将熟制春卷中心温度从80℃冷却至室温20℃,然后于4℃下贮藏18 d。对春卷冷却后的失重率、色泽、气味、质构、感官评价以及贮藏期间的pH值、菌落总数进行测定及对比。结果表明:真空冷却的冷却速率显著高于常规冷却,但产品的质量损失也显著高于常规冷却;真空冷却产品硬度和脆性较高,但色泽、形态、气味感官评价较低,混合冷却可改善真空冷却的缺点;随着贮藏时间的延长,真空冷却和混合冷却对样品pH值的影响较小,且能显著减少微生物污染,从而达到延长货架期的目的。     

Cooked ham classification on the basis of brine injection level and pork breeding country

The aim of this study was to classify whole-leg cooked hams, made without polyphosphates, by linear discriminant analysis. Principal component analysis (PCA) was used for the selection of significant variables. Thirty-two variables were evaluated on 26 cooked hams prepared using different levels of brine injection and legs from pork bred in different countries (France or Denmark). Previously published data related to 20 hams were also used for classification. A chemometric model, based on ten variables, was obtained by using PCA. The variables were pH, moisture, protein, fat, NaCl, superficial wateriness, L* and a*/b* of biceps femoris muscle, modulus and elasticity index of semitendinosus muscle. Discriminant functions calculated using PCA-selected variables enable correct classification of the cooked hams according to the origin of the meat used and, when this is the same, according to the percentage of brine injected.     

蒸制对冷冻荞麦熟面品质的影响研究

为了改善冷冻荞麦熟面的品质特性,采用汽蒸的方式对其进行预处理,研究蒸面预处理对冷冻荞麦熟面品质(面条吸水率、蒸煮损失及质构特性)的影响。同时采用快速黏度分析仪(RVA)和十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(SDS-PAGE)分析蒸面预处理对面条的糊化特性及蛋白质亚基结构的影响。结果表明,汽蒸处理能显著降低面条的蒸煮损失,提高其复热后的硬度、弹性和咀嚼性,并且蒸制3 min时,其总蒸煮损失达到最小值。RVA分析表明,随着汽蒸时间的增加,淀粉的崩解值和峰值黏度降低,而糊化温度增加。SDS-PAGE图谱显示,随着蒸面时间的延长,低分子质量亚基条带的颜色变浅,说明汽蒸可能诱导其发生了交联聚合行为。因此,蒸面预处理可以提高面条的蒸煮特性和质构特性,改善冷冻荞麦熟面的品质特性。     

Feasibility assessment of vacuum cooling of cooked pork ham with water compared to that without water and with air blast cooling

To optimise vacuum cooling for application in the meat industry, an improved cooling method, i.e. vacuum cooling with water (or immersion vacuum cooling), was designed to cool cooked pork ham (2.2 ± 0.2 kg). It was found that the cooling time of vacuum cooling with water was significantly shorter than that of traditional air blast cooling (P < 0.05). For the cooling loss, vacuum cooling with water was significantly lower (6.99%) than that of vacuum cooling without water (13.71%) (P < 0.05). Significant differences in physical and chemical attributes were also observed for ham processed by vacuum cooling with and without water (P < 0.05). Therefore, for a certain size of pork ham, vacuum cooling with water could be an effective method to meet safety guidelines and obtain compatible quality attributes with air blast cooling.     

The effect of scalding on subcutaneous and ham temperatures and ultimate pork quality

Scalding of pig carcasses (n = 34) at 60°C for a period of at least 5·5 to 7·5 min gave satisfactory dehairing results, with the exception of autumn hair for which a longer period (9 mins) was required. Temperature curves were recorded for a subcutaneous position in the ham (n = 26) between the rind and the underlying fat layer. These showed a curve starting at about 30·8°C and increasing to an asymptotic value of 53°C during scalding. Results of calculations with a finite element model of a flat layer of muscle covered with a layer of 1·0 cm fat broadly showed the same temperature increase at about 0·5 cm below the surface as the actual values measured. Immediately after dehairing, about 1·5 mins after finishing scalding, the subcutaneous temperature had already dropped to 46·1 ± 3·0°C, which was considerably higher than the muscle temperature at the same position at a depth of 5 cm under the skin (40·6°C). The heat removal and temperatures during the cooling period after scalding were also calculated. It can be concluded that the increase in temperature due to scalding has only a minor influence on muscle temperature and that meat quality (pH, FOP) is not affected.     

Influence of PSE pork on the quality and economics of cooked, cured ham and fermented dry sausage manufacture

PSE pork (pH(1) ≤ 5·8) and non-PSE pork (5·8 < pH(1) ≤ 6·4) were used for cooked, cured ham production and, with beef, in a 48 52 mixture for fermented dry sausage manufacture. Technological yields of PSE and non-PSE hams were, respectively, 94·0 and 105·9% which corresponded to 5·0 FMK/kg loss for the PSE ham compared to the non-PSE ham. In addition, cooked PSE ham had a poorer organoleptic quality compared to non-PSE ham. However, PSE meat could be mixed with normal meat for the production of fermented dry sausage without quality defects.     

A method for identification of frozen meat used for production of cooked ham

A simple method to distinguish if the meat used for production of cooked hams was frozen or unfrozen was developed. Several analytical parameters of quality in meat products (general and colour parameters and protein fraction) were determined in two types of cooked hams: one elaborated with refrigerated (R) and another with frozen and thawed (F/T) raw hams. Student's t-test was applied to compare both groups, but it could not be concluded if R and F/T cooked hams had the same quality or not. For this reason two multivariate statistical analyses, Factor (FA) and Discriminant Analysis (DA), were applied. The application of FA resulted in the separation of the two groups of cooked hams and allowed the selection of the parameters which were used in Discriminant Analysis (DA). A discriminant function, that is both easy to use and to interpret, was obtained.     

Lactobacillus sakei对真空包装切片火腿的特定腐败研究

研究从真空包装切片火腿中分离得到的腐败菌清酒乳杆菌清酒亚种对该产品品质变化的影响,确定其在低温肉制品中的特定腐败特征。均匀接种104cfu/mL菌悬液于二次杀菌的切片火腿上,真空包装,4℃贮藏,于0、3、7、15、25、35天取样分析:乳酸菌数、pH值、TVB-N值、生物胺变化。结果表明:清酒乳杆菌清酒亚种具有很强的生长竞争力,发酵肉品中的糖类造成pH值下降,形成黏液,并生成酪胺、腐胺等典型腐败生物胺,产生腐败味。L.sakei subsp.sakei是造成真空包装切片火腿发酸变味、发黏起丝、腐败臭味等腐败现象的特定腐败菌。     

Antilisterial activity of lactic acid bacteria inoculated on cooked ham

This study was conducted to evaluate the ability of Lactobacillus sakei 1, a bacteriocin-producing (bac⁺) lactic acid bacterium (LAB), isolated from Brazilian fresh pork sausage to inhibit two Listeria monocytogenes strains (serotypes 4b and 1/2a) on cooked, sliced vacuum-packaged ham. L. sakei ATCC 15521 was used as a non-bacteriocin producer (bac⁻). L. monocytogenes (ca. 2 log CFU/mL) and LAB (ca. 6 log CFU/ml) were inoculated on the sterilized ham, vacuum-sealed and incubated at 8 °C for 10 days. A treatment with the bacteriocin Chrisin (UI/ml) was included. Both L. monocytogenes strains were significantly inhibited in the presence of either bac⁺ and bac⁻ LAB in comparison to the control (L. monocytogenes alone). Using a bacteriocinogenic strain of LAB did not offer an additional barrier to listerial growth in the studied meat system. The application of Chrisin did not affect at all the growth of L. monocytogenes.     

Development of an integrated model for heat transfer and dynamic growth of Clostridium perfringens during the cooling of cooked boneless ham

Numerous small meat processors in the United States have difficulties complying with the stabilization performance standards for preventing growth of Clostridium perfringens by 1 log10 cycle during cooling of ready-to-eat (RTE) products. These standards were established by the Food Safety and Inspection Service (FSIS) of the US Department of Agriculture in 1999. In recent years, several attempts have been made to develop predictive models for growth of C. perfringens within the range of cooling temperatures included in the FSIS standards. Those studies mainly focused on microbiological aspects, using hypothesized cooling rates. Conversely, studies dealing with heat transfer models to predict cooling rates in meat products do not address microbial growth. Integration of heat transfer relationships with C. perfringens growth relationships during cooling of meat products has been very limited. Therefore, a computer simulation scheme was developed to analyze heat transfer phenomena and temperature-dependent C. perfringens growth during cooling of cooked boneless cured ham. The temperature history of ham was predicted using a finite element heat diffusion model. Validation of heat transfer predictions used experimental data collected in commercial meat-processing facilities. For C. perfringens growth, a dynamic model was developed using Baranyi's nonautonomous differential equation. The bacterium's growth model was integrated into the computer program using predicted temperature histories as input values. For cooling cooked hams from 66.6 degrees C to 4.4 degrees C using forced air, the maximum deviation between predicted and experimental core temperature data was 2.54 degrees C. Predicted C. perfringens growth curves obtained from dynamic modeling showed good agreement with validated results for three different cooling scenarios. Mean absolute values of relative errors were below 6%, and deviations between predicted and experimental cell counts were within 0.37 log10 CFU/g. For a cooling process which was in exact compliance with the FSIS stabilization performance standards, a mean net growth of 1.37 log10 CFU/g was predicted. This study introduced the combination of engineering modeling and microbiological modeling as a useful quantitative tool for general food safety applications, such as risk assessment and hazard analysis and critical control points (HACCP) plans.