Wiesław Przybylski

Higher drip loss is associated with protein oxidation

The study aimed to investigate the mechanisms underlying drip loss in meat other than those related to post mortem energy metabolism. The study was carried out on M. longissimus thoracis assessing carcass and meat quality traits plus metabolic parameters and drip loss. Based on the data obtained, three drip loss groups were established: low, medium and high. Heat treatments were performed at 100°C for 30 min. Physicochemical protein modifications were assessed before and after cooking. IMF and L* were higher in the high drip loss group, whereas b* was higher in the medium drip loss group. Residual glycogen, glucose and glycolytic potential were higher in LT muscle from the high drip loss group. Before cooking, protein surface hydrophobicity and carbonyl levels were similar in the three groups. However, after cooking, carbonyl, oxidized actin and oxidized aggregates were higher in the high drip loss group, suggesting that protein oxidation may affect the water holding capacity of meat.

Effect of heat treatment on protein oxidation in pig meat

We investigated the oxidative mechanisms and identified the target protein induced by heat treatment. The study was carried out on M. longissimus thoracis from Galia and Redone pigs. Post mortem metabolic parameters and drip loss were determined. Heat treatment was performed at 100 °C for 10 and 30 min. Physicochemical state of the protein, TBA-RS and Schiff bases were assessed. Protein aggregates were evaluated and the protein target of oxidation studied. Muscles from Galia had higher residual glycogen and drip loss. Heat treatment increased surface hydrophobicity, carbonyl, protein aggregate and Schiff bases and TBA-RS whatever the treatment time. Immunoblotting revealed oxidized myosin, oxidized actin and high molecular weight proteins after 30 min cooking. Oxidation products were significantly correlated with drip loss, suggesting a possible reduced ability of oxidized proteins to retain water. Moreover, residual glycogen was positively correlated with oxidized myosin, suggesting a possible role of glycogen as a glucose donor.

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.

Sensory quality and chemical composition of meat from lambs fed diets enriched with fish and rapeseed oils, carnosic acid and seleno-compounds.

The aim of the study was to evaluate longissimus muscle quality in lambs fed diets including fish oil (FO), rapeseed oil (RO), carnosic acid (CA) and seleno-compounds. Lambs were fed one of diets: Group I - the basal diet (BD) with 3% RO; Group II - BD with 2% RO and 1% FO; Group III - BD with 2% RO, 1% FO and 0.1% CA; Group IV - BD with 2% RO, 1% FO, 0.1% CA and 0.35ppm Se as selenized-yeast; Group V - BD with 2% RO, 1% FO, 0.1% CA and 0.35ppm Se as selenate. The addition of FO and FO, CA and selenium in the inorganic form was characterized by lowest tenderness and juiciness (P<0.05). The lowest concentration of fatty acids (ΣFAs), atherogenic-FAs (A(SFA)) and thrombogenic-FAs (T(SFA)) in the muscle was found for Group V (P<0.05). Experimental diets decreased indexes of A(SFA) and T(SFA) in muscle. The lowest ratio (P<0.05) of n-6polyunsaturated-FAs to n-3polyunsaturated-FAs was obtained for Group III.

3. The Impact of Ante- and Post-Mortem Factors on the Incidence of Pork Defective Meat – A Review

Abstract The occurrence of defective meat depends on factors affecting meat quality at the various stages of meat production. Defective meat has a broad definition and includes any property of meat that will dissatisfy end-users. For consumers the main meat quality features are colour, taste and texture (tenderness and juiciness). For processors and butchers very important are technological quality features: water holding capacity, pH, content of connective tissue, fat and protein. The functionality of defective meat is limited. The risk of incidence of defective meat is a result of the combination of ante-mortem and post-mortem factors. The ante-mortem factors are linked with the procedure at the lairage, the slaughtering factors, such as the method of stunning, and the post-mortem factors, including processing of meat carcasses. The ante-mortem factors such as genotype, gender, breeding conditions, nutrition, transport conditions, stress, weather conditions and the methods of slaughter are considered of primary importance for the quality of pork. It is estimated that 40% of meat defects are due to the procedure at the lairage. The impact of stressors causes a loss of weight of the pigs, contributes, in extreme cases, to the death of porkers, increases the risk of incidence of defective meat. Mixing animals from different herds is the cause of stress which leads to aggression and fights between animals. Limiting the stress factors is essential for improving the quality of pork. The applied stunning method affects the quality of meat. Physical stress during electrical stunning is associated with risk of an accelerated post-mortem glycolysis, contributing to the rapid decrease in pH. In comparison with the electrical method, stunning with carbon dioxide causes less stress in swine. In order to reduce the occurrence of defective meat, bleeding should be carried out as soon as possible directly after stunning. Deterioration of the quality of meat in the production chain can occur at any stage and is most often associated with the lack of compliance with the standards. The studies on the improvement of livestock breeding, transport and marketing carried out over a number of years contributed to the introduction of international standards and, consequently, to the reduction of quality and quantity losses in pork.

The application of biosensors for drip loss analysis and glycolytic potential evaluation.

The aim of this study was to evaluate the relationship between glucose and lactate measured by biosensors in drip loss (strip method) with muscle glycolytic potential and their compounds. On the samples taken from Longissimus dorsi of 24 pigs (pure Neckar hybrid line) the following meat quality traits were determined: pH at 24h, meat color according to CIE L(⁎)a(⁎)b(⁎) system and drip loss. The highest correlations were found between glucose in drip loss and glycogen (r=0.84) or glycolytic potential (r=0.81) in muscle. A significant positive relationship between lactate measured in muscle by enzymatic method and by biosensor in drip loss was established (r=0.76). Glycogen, glucose, lactate and glycolytic potential with meat quality traits as ultimate pH, lightness, b(⁎) value and drip loss were significantly related. Results of multiple regression between glucose as well as lactate measured in muscle drip loss with muscle glycolytic potential showed the possibility of its prediction (r=0.87 with Pα≤0.001).

Sarcoplasmic Protein Profile from Drip Loss in Relation to Pork Quality

The aim of this research was to correlate the sarcoplasmic protein profile of the natural drip loss of muscle with the technological and sensory quality of pork meat. Material for analysis was taken from 14 PenArLan pigs. Simple analysis of relationships between the test protein and meat quality traits showed that they adopt a range of from -0.58 to 0.72. It has been shown that the significance of glycolysis expressed as level of glycogen and lactic acid may be 86% (coefficient of correlations, CR = 0.93), explained by the amount of certain enzymes. The higher relation has been obtained between studied enzymes and value of pH24 , L* and b* parameters of raw meat (98%; CR = 0.99). By contrast, L* and a* parameters, sour flavor, and tenderness of grilled meat in 79% can be explained based on the content of the enolase, glyceraldehyde-3-phosphate dehydrogenase, and phosphoglycerate mutase (CR = 0.89). The results of the multiple regression showed that amount of lactic acid was related to the quantity of the 3 enzymes: phosphofructokinase, AMP deaminase, phosphorylase b/phosphorylase b kinase (r = 0.88).

Relationship between sensory attributes and volatile compounds of polish dry-cured loin

Objective The aim of this work was to determine the relationship between objective sensory descriptors and volatile flavour compound composition of Polish traditional dry-cured loin. Methods The volatile compounds were investigated by using solid phase microextraction (SPME) and gas chromatography–mass spectrometry (GC–MS). For sensory assessment, the quantitative descriptive analysis (QDA) method was used. Results A total of 50 volatile compounds were found and assigned to 17 chemical families. Most of the detected volatile compounds derived from smoking, lipid oxidative reactions and seasoning (46.8%, 21.7%, and 18.9%, respectively). The dominant compounds were: aromatic hydrocarbon (toluene); alkanes (hexane, heptane, and 2,2,4-trimethylpentane); aldehyde (hexanal); alcohol (2-furanmethanol); ketone (3-hydroxy-2-butanone); phenol (guaiacol); and terpenes (eucalyptol, cymene, γ-terpinen, and limonene). Correlation analysis showed that some compounds derived from smoking were positively correlated with the intensity of cured meat odour and flavour and negatively with the intensity of dried meat odour and flavour, while terpenes were strongly correlated with odour and flavour of added spices. Conclusion The analysed dry-cured loins were characterized by specific and unique sensory profile. Odour and flavour of studied loins was mainly determined by volatile compounds originating from smoking, seasoning and lipid oxidation. Obtained results suggest that smoking process is a crucial stage during Polish traditional dry-cured loins production.

Formation of heterocyclic aromatic amines in relation to pork quality and heat treatment parameters

The aim of the research was to analyze the influence of chemical composition, technological and sensory pork quality on the formation of heterocyclic aromatic amines (HAAs) after heat treatment. Material for analysis was taken from 36 samples of pork with different ultimate pH. The results showed that the studied meat was characterized by variation in chemical composition, especially in precursors of HAAs. The formation of HAAs in meat was significantly related to ultimate pH (r = -0.80), glucose concentration (r = 0.60) and color parameters (r = 0.61-0.80). These studies also demonstrated the increased amount of HAAs in meat with higher temperature of grilling. Raising the grill temperature from 180 °C to 220 °C resulted in a two-fold increase in the 4,8-DiMeIQx content and nine-fold 7,8-DiMeIQx. In the case of grilling at 220 °C, the increase in 7,8-DiMeIQx content was accompanied by a decrease in tenderness and juiciness (r = -0.60) and deterioration of overall quality (r = 0.70).

Determinants of the Sensory Quality of Półgęsek in Relation to Volatile Compounds and Chemical Composition

Abstract The objective of this study was to determine the sensory quality of a specific Polish traditional product made from cured and then smoked goose meat (półgęsek) in relation to its volatile compounds and chemical composition. In general, the examined samples contained 66.2% water, 12.2% fat, 17.9% protein, 1.8% connective tissue, and 2.3% NaCl. Moreover, 47 volatile compounds were identified and quantified. The typical decomposition products derived from lipid oxidation, amino acid degradation, carbohydrate fermentation and microbial esterification were the main volatiles detected in all the samples. The volatiles generated by the smoking process and the ones originating from spices were also observed. The results of the sensory evaluation indicated that all the samples of the analyzed products were characterized by a high overall quality. Results of the Principal Component Analysis (PCA) showed, however, that specific groups of products have their own unique sensory profile. Additionally, the sensory analysis confirmed the significant role of the chemical composition and volatile compounds in the development of the overall quality of półgęsek.