Application of PLSR in correlating physical and chemical properties of pork ham with different cooling methods

Partial least squares regression (PLSR) was applied to understand the relationship between physical and chemical properties of pork leg ham with different cooling treatments, i.e., cold room, air blast and vacuum cooling. The results indicated that overall 69.8% variation of physical matrix was explained by chemical matrix. For the univariate analysis of physical attributes, the results showed that gumminess (88.1%) and hardness (86.5%) were best explained by chemical matrix, followed by springiness (78.7%), Warner–Bratzler Shear force (61.3%), and a* (60.0%). Graphical display of the regression coefficients indicated that different cooling treatments had different effects on the physical property of pork ham. Therefore, to predict the physical quality with chemical attributes, separate regression formulations should be adopted for different cooling methods. These findings have practical importance in attempts to predict physical properties from chemical components. In addition, they can also be used to control the physical properties by adjusting the components in the meat system.     

Chemical, instrumental and sensory characteristics of cooked pork ham

Instrumental, chemical and sensory parameters of cooked pork ham were evaluated. Principal component analysis was carried out on the basis of the instrumental variables related to colour and texture. The four PCs account for almost 94% of the total variance in the data set. The PCA only separated 3 hams with a^* > 10. Hardness was correlated with non-collagen muscle protein (P  0.01), gumminess (P  0.01) and ash (P  0.05). Sensory evaluated tenderness showed positive significant correlation with L^* (P  0.01). The most important colour parameter seems to be a^*, which was negatively correlated with sensory evaluated parameter colour (P  0.01). The PCA performed on all parameters (sensory, chemical and textural) discriminated two groups of hams differing in non-collagen muscle protein content and hardness.     

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.     

西式火腿煮制过程中品质变化动力学研究

结合动力学方法对西式火腿煮制过程中成熟品质因子(颜色、剪切力)和过热品质因子(水分含量)变化进行反应动力学测定和分析。结果表明:煮制过程中,西式火腿颜色、水分含量和剪切力的变化均遵循一级反应动力学。亮度值和红度值的z值分别为49.69,41.85℃,值分别为46.73,55.27 kJ/mol;剪切力的z值为34.81℃,Ea值为66.69 kJ/mol;水分含量的Ea值为52.22 kJ/mol,z值为44.45℃,大于剪切力和红度值的z值。成熟品质因子的z值小于过热品质因子z值,符合烹饪操作优化的要求,证明西式火腿煮制过程存在优化空间。     

Meat quality and cooking attributes of thawed pork with different low field NMR T(21)

A relationship of low field NMR T(2) components to meat quality and cooking attributes of pork was investigated. Longissimus muscle was removed from 23 pig carcasses at 24h postmortem for meat quality measurements and cooking test. Frozen samples were classified into three groups by LF-NMR T(21) of thawed samples: A (<40ms), B (40-44ms) and C (>44ms). There were significant differences (P<0.05) in pH, lightness (L* value) and pressing loss among the three groups. Cooking time to attain 70°C was slightly lower in group C than the other groups. Shear force value of cooked samples was not affected by T(21). The component T(21) correlated (P<0.05) with L* value, muscle pH and pressing loss, while L* value correlated (P<0.05) with thawing loss and muscle pH. Therefore, combined LF-NMR and color measurements could be a good way to differentiate water holding capacity of pork.     

Effect of low-temperature preservation on the quality of vacuum-packaged dry-cured ham: Refrigerated boneless ham and frozen ham cuts

The effect of storage on dry-cured ham quality was studied. Sixteen vacuum-packaged boneless dry-cured hams and sixteen vacuum-packaged dry-cured ham cuts were stored in darkness under refrigeration (4±2°C; 8 months) or freezing (-18±1°C; 24 months), respectively. Instrumental colour and texture, physico-chemical and biochemical parameters, sensory profile and consumer acceptability and purchase satisfaction were measured throughout storage. The overall quality of refrigerated boneless dry-cured hams and frozen dry-cured ham cuts showed only limited changes throughout long-term storage. Significant changes involved loss of odour and flavour, increased adhesiveness and modification of hardness, the Semimembranosus muscle became tender while Biceps femoris became harder, leading to a higher textural homogeneity. In agreement with those changes, the overall acceptability assessed by a trained panel decreased throughout storage, though this was significant regarding only frozen hams. However, consumer evaluation of acceptability, as well as satisfaction with hypothetical purchasing, did not vary significantly throughout storage.     

Physico-chemical, textural and structural characteristics of sous-vide cooked pork cheeks as affected by vacuum, cooking temperature, and cooking time

This paper describes the influence of different factors on sous-vide cooked pork. Pork cheeks were cooked at different combinations of temperature (60 °C or 80 °C), time (5 or 12 h) and vacuum (vacuum or air packaged). Weight losses were lower and moisture content higher in samples cooked for a shorter time (P = 0.054) and at a lower temperature (P < 0.001). Samples cooked at 60 °C showed more lightness (L*) and redness (a*) (P < 0.001). Lipid oxidation showed an interaction between cooking time and temperature (P = 0.007), with higher TBARs values for samples cooked for 12 h at 60 °C and lower for those cooked for 12 h at 80 °C. Samples cooked at 80 °C for 12 h showed lower (P < 0.05) values for most textural parameters than all the other types of samples. Vacuum packaging showed no influence on any of the studied variables. For the treatments evaluated, cooking temperature × time combination seems to be more important than vacuum packaging in the textural and colour parameters of pork cheeks.     

Effects of processing parameters on immersion vacuum cooling time and physico-chemical properties of pork hams

The effects of agitation (1002 rpm), different pressure reduction rates (60 and 100 mbar/min), as well as employing cold water with different initial temperatures (IWT: 7 and 20 °C) on immersion vacuum cooling (IVC) of cooked pork hams were experimentally investigated. Final pork ham core temperature, cooling time, cooling loss, texture properties, colour and chemical composition were evaluated. The application for the first time of agitation during IVC substantially reduced the cooling time (47.39%) to 4.6 °C, compared to IVC without agitation. For the different pressure drop rates, there was a trend that shorter IVC cooling times were achieved with lower cooling rate, although results were not statistically significant (P > 0.05). For both IWTs tested, the same trend was observed: shorter cooling time and lower cooling loss were obtained under lower linear pressure drop rate of 60 mbar/min (not statistically significant, P > 0.05). Compared to the reference cooling method (air blast cooling), IVC achieved higher cooling rates and better meat quality.     

Automatic measurement of pores and porosity in pork ham and their correlations with processing time, water content and texture

Pores formed in pork ham have a significant effect on its quality. However, they are mostly characterised using manual methods with special devices. In this paper, an automatic method for pore characterisation of pork ham was developed using computer vision. To segment pores from images of pork ham, three stages of image processing algorithm were developed, i.e., ham extraction, image enhancement, and pore segmentation. From the segmented pores, the porosity, number of pores, pore size, and size distribution were measured. The statistical analysis showed that 79.81% of pores have area sizes between 6.73×10(-3) and 2.02×10(-1)mm(2). Furthermore, it was found that the total number of pore (TNP) and porosity highly negatively related to the water content of pork ham (P<0.05), and had negative correlations with the cooking and cooling time. However, for texture analysis, positive correlations were found between the pore characterisations and WBS, hardness, cohesion, and chewiness, respectively, while springiness and gumminess were negatively related to TNP and porosity.     

Effect of tiger nut fibre on quality characteristics of pork burger

Horchata is a refreshing beverage obtained from tiger nut tubers that yields high amount of by-products. These by-products have a high content of fibre that allows its application in the development of dietary fibre rich foods. The utilization of increasing levels (0%-control, 5%, 10% and 15%) of tiger nut fibre (TNF), in the formulation of pork burgers was evaluated. This evaluation was based on: chemical composition, physicochemical, cooking characteristics and sensory properties of burgers. Pork burgers elaborated with TNF had higher nutritional value (higher fibre content) and better cooking characteristics (higher cooking yield, fat retention and moisture retention) than control burgers. Some of the negative changes in colour (a* decrease and b* increase) and texture (chewiness and springiness increase) parameters due to TNF addition observed in raw burgers were masked by the stronger modifications due to the cooking process. Burgers with TNF were perceived as less greasy, less juicy, more grainy and with less meaty flavour than controls; although this perception did not reduce the overall acceptability of burgers. Overall acceptability scores were slightly lower in burgers with 15% TNF, although no significant differences were detected with the scores of control, 5% and 10% TNF burgers. TNF addition to burgers is a promising and convenient application as dietary fibre of burgers was significantly increased without changes in sensory acceptance.     

烹饪方式对猪肉品质及营养成分的影响

以猪背最长肌肉为研究对象,比较分析烹饪方式(蒸、煮、炸和烤)对其肉品质、常规营养成分、氨基酸和脂肪酸含量的影响。结果显示:与新鲜对照相比,烹饪加工后pH值、水分含量显著降低(P0.05);硬度、弹性、黏着性、灰分和粗蛋白、PUFA含量显著提高(P0.05);炸和微波的烹饪损失率显著高于蒸、煮和烘烤的(P0.05);煮的灰分含量无显著变化(P0.05),其它烹饪方式均显著升高(P0.05);炸的粗脂肪含量显著降低(P0.05),其它烹饪处理均显著升高(P0.05);烘烤显著降低了TAA含量(P0.05),其它烹饪方式均显著提高(P0.05);烘烤的DAA和EAA含量无显著变化(P0.05),其它烹饪方式均显著提高(P0.05);所有处理的EAA/TAA达到40.00%,EAA/NEAA67.00%;烹饪处理后必需氨基酸评分基本大于FAO/WHO计分模式,第一限制性氨基酸均为Val。说明烹饪处理对猪肉物理性质有不利影响,但可不同程度提高其营养价值。因此,日常生活中要根据实际需求选择适宜的烹饪方式,达到合理膳食的目的。     

The effect of cooking conditions on the formation of volatile heterocyclic compounds in pork

Headspace volatiles from grilled, roast and boiled pork were entrained on Tenax GC and analysed by combined gas chromatography-mass spectrometry. Well-done grilled pork contained 66 heterocyclic compounds including pyrazines. thiazoles, thiophenes, furans and pyrroles, many of which had not previously been found in cooked pork. The pyrazines accounted for almost 80% of the total headspace volatiles, although most of the other heterocyclic compounds were present only in small amounts. Pork cooked by less severe grilling or by roasting or boiling contained considerably fewer heterocyclic compounds, and headspace volatiles were dominated by aldehydes and alcohols originating from thermal oxidation of lipid.     

Effect of protein level in commercial diets on pork meat quality

This study assessed the effect of protein level on meat quality, intramuscular and subcutaneous fat, instrumental texture and sensory attributes on Longissimus dorsi in pork. Animals were fed two experimental diets that produced two animal groups with different percentages of intramuscular fat (IMF) (1.76 vs. 2.63). There were no significant differences in meat quality or texture profile analysis parameters between IMF groups. The percentage of saturated fatty acids was also similar, but the percentage of monounsaturated was significantly higher in the group with higher IMF and the percentage of polyunsaturated fatty acids was higher in the group with lower IMF. IMF groups had little effect on the fatty acid composition of subcutaneous fat. Warner-Bratzler shear force (WBSF) values were significantly higher in the group with lower IMF, whereas tenderness was higher in the group with higher IMF. Finally, WBSF appeared to be a good predictor of the tenderness for grill-cooked pork.     

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.     

Effect of vacuum and modified atmosphere packaging on the quality of pork loin

The effect of packaging in protective atmospheres on the process of lipid oxidation, colour and water retention capacity of pork loin chops during refrigerated storage was investigated. The use of modified atmospheres with a high oxygen concentration (70%) acted as a pro-oxidation factor both for fatty acids and for cholesterol (an increase of 86.4% on the initial COPS content). No significant advantages were found in the use of these atmospheres concerning the colour of the meat. Vacuum packaging was seen to be an interesting alternative in the packaging of pork, due to the fact that it increases oxidative stability, which brings about greater colour stability and therefore increases the shelf life. The only disadvantage of this type of packaging is that it increases initial weight loss (5.1% on day 2 of storage).     

Effect of cooking method on water absorption and ease of dehulling in preparation of African locust beans for Iru

Gas boiling or pressure cooking increased the level of water uptake by locust beans over that with firewood cooking, mainly because of sustained heat input. Presoaking in cold water produced no advantage. The boiling times necessary for satisfactory dehulling were 10h using firewood, 6h by gas boiling, and 30 and 50min respectively by pressure cooking at 121 and 115°C.     

Effect of semolina replacement with a raw:popped amaranth flour blend on cooking quality and texture of pasta

The replacement of semolina (SEM) with raw:popped (90:10) amaranth flour blend (AFB) in pasta making at 25, 50, 75, and 100 g/100 g levels (flour basis, 14 g of water/100 g) was carried out to evaluate the effects on cooking quality and texture of the supplemented pasta samples. Significant differences on cooking quality characteristics and texture of the pasta samples were observed. The pasta solid loss increased, weight gain and firmness decreased as the AFB level increased. The semolina pasta showed the lowest solid loss (7 g/100 g) and the highest weight gain (188.3 g/100 g) and firmness (1.49 N), whereas the amaranth blend pasta was the softer (around half of the firmness of semolina pasta) and lost the higher amount of solids (11.5 g/100 g). The raw and popped AFB was suitable for increasing the nutritional quality through dietary fiber and high quality protein and even to obtain gluten-free pasta with acceptable cooking quality (solid loss of 3.5 g/100 g higher than that considered as acceptable for semolina pasta). The amaranth blend used in this study enables the partial or total replacement of wheat semolina in pastas with acceptable cooking quality and texture.