Injection of water and polyphosphate into pork to improve juiciness and tenderness after cooking

Two injection levels (5 and 10%) and three concentrations of polyphosphate (0, 3 and 5%) were used in 64 pork loin portions to assess the influence of polyphosphate injection on eating quality of pork steaks cooked by grilling to a centre temperature of 72.5 or 80°C and assessed by a trained ten member sensory panel. Polyphosphate improved water holding, and generally produced more tender and more juicy meat than control steaks, although pork flavour intensity was reduced and abnormal flavour intensity increased. Raising the centre temperature from 72.5 to 80°C increased the cooking loss from 35 to 42%, reduced tenderness, juiciness and abnormal flavours and increased pork flavour intensity. Steaks containing 5% polyphosphate and cooked to 80°C were more tender and as juicy as steaks without polyphosphate cooked to the lower centre temperature. These effects were generally larger than those that can be achieved ‘naturally' by, for example, changing diets and breeds but whether the technology will be utilised in an increasingly ‘additive free' climate is debatable.     

Influence of cooking conditions on cooking loss and tenderness of raw and marinated chicken breast meat

The influence of different cooking treatments on tenderness and cooking loss, as main quality characteristics of chicken breast meat, was investigated. Industrial skinless chicken breast meat samples were designated as raw and marinated and cooked in the oven by hot air and hot air-steam mixture at 130, 150 and 170 °C, for 4, 8 and 12 min. Cooking losses were evaluated by weight changes before and after cooking, and tenderness changes were determined on cooked samples by measuring shear force using instrumental texture analysis. Results showed that marination, followed by air-steam cooking is the best combination to obtain the most tender chicken breast slices. The time and temperature of cooking showed similar effects on cooking loss and tenderness: short cooking time (4 min) and temperatures of 130–150 °C resulted in lower cooking losses and best meat tenderness, in both not marinated and marinated meat. Statistically significant correlations between tenderness and cooking loss indicated that the cooking loss correlated better with cooking time than with cooking temperature. An opposite phenomenon was observed for meat tenderness.     

Prediction of technological quality (cooking loss and Napole Yield) of pork based on fresh meat characteristics

In order to investigate if cooking loss and Napole Yield can be predicted from various fresh meat characteristics, pH (1, 15, 30, 60, 120 min and 24 h post mortem), temperature (1, 15, 30, 60, 120 min and 24 h post mortem), water-holding capacity (Honikel's drip loss method and centrifugation loss), and NMR T2 relaxation 24 h post mortem were measured in fresh porcine M. longissimus dorsi from 102 Hampshire crossbreeds of known RN(-) genotype. Subsequently, cooking loss and Napole Yield were determined on cooked and cured, cooked samples, respectively, and partial least squares regression (PLS) was carried out to investigate possible intercorrelations between the physico-chemical measurements performed on the fresh meat and cooking loss/Napole Yield. Significant correlations were found between NMR T2 relaxation measured in fresh pork 24 h post mortem and the cooking loss (R=0.64) and Napole Yield (R=0.58), whereas no correlations were found between traditionally applied methods such as pH measurements, Honikel's method and centrifugation, and the cooking loss/Napole Yield. Consequently, it is concluded that NMR T2 relaxation characteristics of fresh pork in contrast to traditional fresh meat characteristics contain information about factors of importance for cooking loss/Napole Yield from cooked uncured/cured pork. The result implies that low-field (LF) NMR data from fresh meat reflects information about water compartmentalisation and mobility that is partly decisive for subsequent heat-induced changes of importance for the distribution of water within the cooked meat. In addition, the obtained results show that LF NMR data measured on fresh meat also seems to contain information about the inherent water of importance for the technological characteristics of the meat even when the meat is cured before cooking.     

Flavour formation in pork semimembranosus: Combination of pan-temperature and raw meat quality

Flavour development and overall eating quality of pork semimembranosus were investigated with regard to different raw meat qualities (feeding/fasting strategy; control/low glycogen level, gender; castrate/female, slaughter live-weight; 84 kg/110 kg) combined with frying temperature (150 °C/240 °C). It was further investigated whether the precursor levels of glycogen, IMP, inosine, and hypoxanthine in the raw meat were correlated to the raw meat quality and fried/grilled attributes. Pork schnitzels were fried on a pan (155 °C) or grill–pan (240–250 °C) to a core temperature of 70 °C. Frying temperature was the one factor with greatest influence on the sensory attributes, and pan-grilled schnitzels had significantly higher scores in fried/grilled attributes regardless of meat quality compared to pan-fried schnitzels. Texture was not appreciably influenced by any treatment. There was no correlation between precursor levels and raw meat qualities or fried sensory attributes. Gender and slaughter live-weight had no pronounced influence on flavour and overall eating quality.     

Sensory and meat quality traits of pork in relation to post-slaughter treatment and RN genotype

The effects on eating quality and meat quality of two different forms of post-slaughter treatment, performed in an abattoir, were studied in carriers and non-carriers of the RN(-) allele. Carcasses were subjected to rapid and slow chilling, and pelvic and Achilles suspension in a factorial experimental design. A temperature of 10?°C was achieved in the centre of M. longissimus dorsi (LD) within 3.5 h in rapidly chilled carcasses and within 8 h in slowly chilled carcasses. In deep M. semimembranosus (SM) a temperature of 10?°C was achieved within 11.5 h in rapidly chilled carcasses and within 14 h in slowly chilled carcasses. LD from slowly chilled RN(-) carriers suspended by the pelvis exhibited the greatest tenderness, while LD from rapidly chilled non-carriers suspended from the Achilles tendon exhibited the lowest tenderness. Pelvic suspension or slow chilling of non-carriers produced the same improvement in tenderness, and when combined the tenderness increased further. However, the tenderness of the RN(-) carriers was already high, and no significant improvement was seen following any of the studied post-slaughter treatments. Pelvic suspension prevented shortening of muscle fibres, as seen by longer sarcomeres in LD from pelvic-suspended sides. However, longer sarcomeres were associated with greater tenderness only in LD from non-carriers of the RN(-) allele. The presence of the RN(-) allele and a slow chilling regime increased the rate of pH decline in LD. Achilles suspension also increased the rate of pH fall in SM, in addition to the RN(-) allele and slow chilling. The overall tenderness of LD was mainly related to the course of pH decline during rigor; lower pH values between 3 and 7 h post-mortem contributing to greater tenderness. The myofibrillar length was predominantly related to RN genotype and was shorter in RN(-) carriers than in non-carriers. The RN(-) allele and slow chilling contributed to higher evaporation losses and RN(-) carriers exhibited increased frequency of PSE meat in the ham muscles. The use of pelvic suspension appears advantageous over slower chilling, since it improved tenderness without any negative influence on drip loss, evaporation or cooking loss.     

Technological and sensory pork quality in relation to muscle and drip loss protein profiles

Fifteen meat samples collected from pigs (Neckar hybrid line) were selected from 75 animals on the basis of their technological quality traits, and the samples were classified as normal, PSE, and acid meat. Sensory analysis was performed on the three meat categories. Total meat protein and drip loss protein were analyzed by electrophoresis (SDS-PAGE), mass spectrometry, and image analysis. From a sensory point of view, PSE meat was characterized by lower color intensity, and acid meat was characterized by the lowest score of juiciness. Certain soluble proteins derived from the drip loss were associated with meat quality, especially phosphoglucomutase and the B chain of hemoglobin in the case of PSE and acid meat. Low quantities of myofibrillar proteins (myosin LC1, troponin T (TnT) and troponin C (TnC)) in meat with high glycogen levels and low pH levels resulted in a higher rate of proteolysis of myofibrillar proteins due to higher enzymatic proteolysis activity in the meat. The results of this study showed that the TnC/TnI ratio may be a pertinent marker of postmortem muscle metabolism and that this ratio is related to textural properties.     

Salmonella in raw meat and by-products from pork and beef

After campylobacteriosis, salmonellosis is the second main cause of human bacterial enteritis in Germany. Salmonella is known to colonize the gastrointestinal tract of animals without producing any clinical signs. Therefore, carcasses can become contaminated with Salmonella at the time of slaughter. During an 11-month period, a total of 4,170 raw meat samples and by-products from beef and pork, obtained from seven different slaughterhouses in Southern Germany, were screened by the VIDAS system for Salmonella in this study. Positive results were confirmed by isolation of the pathogen on selective agars. The overall percentage of Salmonella-positive samples was 1.4% by the VIDAS system and 0.7% by culture confirmation. Salmonella was detected in 1.8% of pork samples by the VIDAS system and in 1.1% of samples by culture. In beef samples the presence of Salmonella was verified in 0.6% of samples by the VIDAS system and in 0.1% by culture on selective agars. The highest contamination rates were found in porcine and bovine tongue samples. Salmonella was detected in porcine samples throughout the year, except in samples collected in July, and a slight increase was observed in the colder months. The VIDAS system was shown to be an efficient screening method for the detection of Salmonella, with the advantage of a reduced analysis time.     

Consumers' expected quality and intention to purchase high quality pork meat

Expected quality is believed to be one of the most important factors that influence consumers' intention to purchase food. The present study seeks to explore the concept of pork meat expected quality and compare it with self-stated consumer intention to purchase pork meat. The aim is attempted by means of a field research conducted in Greece, following a conjoint analytic procedure. Results show that quality expectations comply with intention to buy pork, in many aspects. However, several differences have been identified. More specifically, country of origin and marbling appear to be more important for respondents' purchase decisions than they are for their quality evaluations, while the opposite appears to be true for price. Finally, socio-demographic factors such as gender, level of education, place of purchase and consumption habits seem to influence perceptions.     

Low-frequency dielectric spectrum to determine pork meat quality

The use of dielectric spectra to determine meat quality classes (PSE, DFD, RFN) in porcine muscle during postmortem period was evaluated. The changes in dielectric properties during meat ageing were also analyzed for each meat quality class. For these purposes, dielectric spectra were measured from 100 Hz to 0.4 MHz in parallel and in perpendicular to muscle fiber directions. Significant differences (p < 0.05) in dielectric constant and loss factor among classes were observed at 24 and 48 h post-mortem. Thus, the use of dielectric properties to detect low meat qualities is more reliable at 24 h after slaughtering. Moreover, two indexes for evaluating meat ageing were developed from dielectric properties with good results. This research is the first step for developing a sensor based on electromagnetic waves at radio frequencies for controlling pork meat quality. The results are promising and some definite frequencies are demonstrated to be useful for these purposes.Industrial RelevanceThe results of this research article are demonstrated to be useful for discriminating low meat qualities (PSE and DFD meats). Thus, the industrial relevance is clear in this case because the detection of low meat qualities is identified as one of the most important challenges of meat industry nowadays. On the other hand, basing on the results of the present paper it is possible to develop a prototype for industrial applications. Moreover, two possible Indexes are developed in the present paper for determining meat freshness which also can be considered important from an industrial point of view. All this determinations were made by using dielectric spectroscopy which can be considered an emerging technology. For all these reasons we are sending to this journal “Innovative Food Science and Emerging Technologies” our results.     

Effect of age and cut on cooking loss, juiciness and flavour of South African beef

The juiciness and flavour characteristics of 15 aged primal beef cuts of electrically stimulated carcasses, from three different age groups, were assessed (n=61). Cooking losses were determined and proximate analyses (moisture, fat, nitrogen and ash) were performed. Tender cuts were cooked by a dry heat method, and less tender cuts were cooked by moist heat methods. A trained panel (n=10) evaluated sensory quality characteristics including initial and sustained juiciness, aroma and flavour. Flavour intensity was the biggest discriminant between the three age groups and declined with an increase in age. Initial impression of juiciness decreased with increased age of the animal and cooking losses increased nonlinearly with age, irrespective of the muscle. In contrast sustained juiciness increased with increased age. Cuts cooked according to a dry heat cooking method were reported juicier (both initial and sustained) than those cooked by moist heat methods.     

The influence of breed,gender, and PSS (Halothane) genotype on meat quality,cooking loss,and palatability of pork

A total 851 swine of four breeds (Duroc, Hampshire, Landrace, and Yorkshire), three genders (barrows, gilts, and boars) and two PSS (halothane) genotypes (carriers and non-carriers of the halothane gene) were evaluated for meat quality, cooking, and palatability traits. Breed exerted a major influence on meat quality, cooking, and palatability traits. The most palatable meat was produced by Hampshires and the least desirable meat was produced by Yorkshires. Although juiciness was negatively correlated with cooking loss (r=−0.60), meat from Hampshires received the highest ratings for juiciness, despite sustaining the greatest cooking losses. Gender exerted minor influences on meat quality and palatability attributes, and no indication was obtained genders differed sufficiently in palatability to warrant discrimination based upon gender. Therefore, entire males can be utilized to capitalize on reported production advantages without influencing palatability, particularly if adequate means for screening boar taint are available for carcasses from heavier or more mature animals. Halothane genotype exerted substantial influence on meat quality traits and statistically significant but relatively minor influence on palatability traits. Carriers of the halothane gene produced meat which was of clearly inferior quality to the meat produced by non-carriers. Carriers of the halothane gene consistently produced a higher proportion of unacceptable chops than non-carriers, although differences were not statistically significant.     

Relationship between meat quality and cooking losses

Summary. On the basis of visual assessment of exudative appearance, hams and shoulders were divided into two categories before curing: the 'normal' and the exudative ones. The 'normal' category included the DFD (dark, firm, dry) and the intermediate types having significantly lower average cooking loss. Since the two conditions are easily recognized, a preliminary selection is quite efficient. The efficiency of selection depends on the incidence of exudative meat to be processed. In the case of high incidence, selection may improve uniformity of pork products by decreasing cooking losses.     

欧姆加热过程对猪肉氧化和体外消化率动态变化的研究

本文研究了欧姆加热与水浴加热肉块到一定的终点温度（20¹00℃）时,脂肪和蛋白质氧化、蛋白质表面疏水活性和聚合度、胃蛋白酶、胰蛋白酶和α-凝乳蛋白酶体外消化率的动态变化。结果显示:随着肉块终点温度的升高,蛋白质羰基呈现先下降后上升的趋势,而胰、α-凝乳蛋白酶体外消化率呈现一定的下降趋势。当肉块温度为40℃时,欧姆加热组的蛋白质表面疏水活性显著低于（p<0.05）水浴加热处理组。当肉块温度为20℃时,欧姆加热组的胰、α-凝乳蛋白酶消化率显著高于水溶加热处理组（p<0.05）。当肉块温度为60℃时,欧姆加热组的羰基值和胃蛋白酶体外消化率显著低于（p<0.05）水浴加热处理组,而胰、α-凝乳蛋白酶体外消化率显著高于（p<0.05）水浴加热处理组。当肉块温度为80℃时,欧姆加热组的硫代巴比妥酸值显著低于（p<0.05）水浴加热处理组。其余各指标各处理组无显著差异（p>0.05）。蛋白质聚合度、蛋白质疏水活度与胃蛋白酶体外消化率呈现显著负相关关系（p<0.05）,因此欧姆加热肉品节约了总加热时间的1/2⁵/6,氧化、体外消化率各指标与水浴加热处理组整体上无明显区别。      

Chemical and sensory characterisation of pan-fried pork flavour: Interactions between raw meat quality, ageing and frying temperature

The effect of raw meat quality and cooking temperature on flavour generation in pork was investigated. The semimembranosus muscle was varied through genetics (carrier (HLY) and non-carrier (DLY) of the RN(-) allele) and ageing at 2°C (2, 15, and 22 days), whereas the pan-frying temperatures were 150°C and 250°C. HLY gave more pronounced 'fried' and 'burnt' notes than DLY after frying. This could partly be explained by a significantly higher concentration of glucose and glucose 6-phosphate in HLY after 22 days of ageing. HLY was generally perceived as more sour, which correlated well with the measured pH of HLY, but not to the l-lactate concentration. HLY was furthermore perceived as more tender and juicier than DLY, both attributes increased during ageing. Lipid-derived aroma volatiles dominated the samples fried at 150°C, while those from Maillard reactions mostly prevailed in the aroma profile at 250°C.     

Desorption isotherms and isosteric heat of desorption of previously frozen raw pork meat

Some meat products involve drying previously frozen pork meat, which makes the knowledge of sorption characteristics very important for the design and management of meat dehydration processes. The sorption isotherms of raw pork meat from the Biceps femoris and Semimembranosus muscles were determined at four temperatures: 25, 30, 35 and 40 °C. The experimental results were modelled using the GAB (Guggenheim, Anderson and De Boer) model. The effect of temperature was also taken into account to model the experimental sorption isotherms using four models (GAB, Oswin, Halsey and Henderson). The best results were provided by the GAB model. From the experimental sorption isotherms the isosteric heats of sorption were determined. For a moisture content higher than 0.15 kg water/kg dm, the isosteric heat of meat was similar to the latent heat of vaporization for pure water. For a lower moisture content, an increase in the isosteric heat was observed when the moisture content decreased.     

Effect of cooking bag and netting packaging on the quality of pork ham during water cooking

As a preliminary test for combining water cooking with vacuum cooling in soup of pork ham, three package treatments were designed to study the effect of cooking bag and netting on the quality of water cooked ham, i.e. ham cooked with a cooking bag and without a cooking bag (single netting and double netting). For treatments without a cooking bag, the results indicated that there was no significant superiority of ham cooked with double netting compared with ham cooked with single netting on the processing efficiency and quality characteristics. Although the hams cooked with a bag performed better in some chemical retentions and pigment, the water contents were significantly lower than those hams cooked in single netting (P<0.05), and there was a higher shrinkage tendency compared with the hams cooked without a bag. For the processing characteristics and texture properties of pork ham, there were no significant differences observed among the treatments with and without a cooking bag in terms of the combined effect of cooking and cooling (P>0.05). By considering the safety, convenience, cost, and the recovery effect on the quality changes of ham during vacuum cooling in soup, cooking with single netting is a better choice for future research.     

宰后电压刺激对猪肉质的影响

本实验运用三种电压460V,220V,和85V,频率60HZ,对纯种无应激杜洛克猪眼肌肉样进行90秒的电刺激,后测定了pH、嫩度、滴水损失、L*值、a*值、b*值、水浴损失.结果发现,电击能改善肉的嫩度,导致肉的a*值降低,L*值、b*值升高,系水力下降,且在不产生PSE肉的前提下,肉的嫩度值、L*值、b*值随刺激电压的升高而升高,a*值、系水力随刺激电压的升高而降低.但电压对肉的水浴损失无明显影响.     

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 eating quality of pork

Two experiments were conducted to examine the effects of cooking parameters, including final internal temperature (65, 72·5 or 80°C), on the eating quality of pork. Assessments were made by a 10-member trained taste panel. In Experiment 1 on loin steaks (m. longissimus) from 28 carcasses weighing 66 ± 1·9 (SD) kg, increasing the final internal temperature from 65 to 80°C had the following effects on mean scores (1-8): tenderness -1·0; juiciness -1·5, pork flavour +0·6 and abnormal flavour -0·5. The medium temperature of 72·5°C was suggested as ideal. In Experiment 2 on leg roasts (m. gluteobiceps) from 96 carcasses weighing 65 + 2·7 (SD) kg, increasing the final internal temperature from 65 to 80°C had the following effects on mean scores (1-8): tenderness -0·2 (not significant), juiciness -0·6, pork flavour +0·3 and abnormal flavour -0·5. The effects of final internal temperature were therefore smaller in roasts and temperatures towards the upper end of the range would be recommended for ideal eating quality, balancing small losses in tenderness and juiciness against gains in flavour scores. Although the experiments were not designed to examine source and sex effects there was evidence that tenderness can be improved through the use of Duroc genes and pelvic suspension of carcasses and no evidence of differences in eating quality between entire males and females.     

Muscle protein changes post mortem in relation to pork quality traits

The relationship between post-mortem traits of muscle proteins and water loss traits was investigated using 84 pork loins representing the four quality traits of PSE, RSE (reddishpink, soft, exudative), RFN (reddish-pink, firm, non-exudative) and DFD. Protein solubility measurements (sarcoplasmic, myofibrillar and total) were lower and myosin denaturation (quantified by myofibrillar ATPase activity) was higher for PSE samples compared with samples from the other quality classes. RSE samples were similar to RFN samples in protein solubility and myosin denaturation, although RSE had lower values then DFD samples for protein solubility measurements. RFN samples had lower drip, thaw, cook and total water loss than RSE samples and all water loss traits were lowest for DFD samples and highest for PSE samples. Insoluble phosphorylase was the only characteristic that differentiated among PSE, RSE and RFN samples. SDS-PAGE and Western blots indicated that in PSE and RSE samples, the myofibrillar protein titin was less degraded and nebulin was more degraded compared with RFN and DFD samples. SDS-PAGE of extracted and unextracted myofibrils showed that the reduced myofibrillar solubility of PSE samples was caused by decreased extractability of the myosin heavy chain in these samples. In conclusion, although RSE samples have unacceptably high water loss, muscle protein denaturation was minimal and did not explain the low water-holding capacity.