Danuta Jaworska

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.

The Effect of LAB as Probiotic Starter Culture and Green Tea Extract Addition on Dry Fermented Pork Loins Quality

The objective of this study was to evaluate the microbiological, physicochemical, and sensory quality of dry fermented pork loin produced with the addition of Lb. rhamnosus LOCK900 probiotic strain, 0.2% glucose, and 1.5% green tea extract. Three loins were prepared: control sample (P0: no additives), sample supplemented with glucose and probiotic strain (P1), and sample with glucose, green tea extract, and probiotic (P2). The samples were analyzed after 21 days of ripening and 180 days of storage. The results indicated that the highest count of LAB was observed both in the samples: with probiotic and with probiotic and green tea extract (7.00 log cfu/g after ripening; 6.00 log cfu/g after storage). The oxidation-reduction potential values were lower in the probiotic loin samples. Probiotic and green tea extract have not caused color changes of study loins during storage. The study demonstrated that an addition of probiotic and green tea extract to dry fermented loins is possible and had no impact on sensory quality after product storage.

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.

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).

Texture Assessment of Industrially Produced Spreadable Fat Fortified with Fish Oil

Each year the assortment of fish oil fortified foods increases. Fish oil is a rich source of long chain omega-3 polyunsaturated fatty acids (PUFA) which low intake results in less protection against many common diseases. According to recommendations the level of omega-3s in average diet should be increased. Consumption of foods fortified with fish oil may elevate omega-3 intake. Such fortification, among others, may influence the texture of food product because of liquid form of added fish oil. The aim of this study was to evaluate the influence of fortification with 30 g kg-1 of fish oil on selected texture properties of reduced-fat spread by sensory and instrumental assessment during 3 months of storage. Samples were prepared on industrial pilot plant. Hardness, spreadability, consistency and adhesiveness were measured by sensory and instrumental methods (Texture Analyser TX.TA2i). During storage time results of measurements of all evaluated attributes were comparable to controls. Slight increase in hardness and consistency was observed. It is concluded that fortification with 30 g kg-1 of fish oil used in the study has no significant effect on texture properties of evaluated spread. Combined instrumental and sensory methods may assure precise assessment of texture parameters in the quality control of spreadable fat production.

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.

Possibilities of Calcium Fortification of Spreadable Fat

The aim of the study was to evaluate selected quality attributes of low-fat spread fortified with calcium complex isolated form cow milk. Calcium preparations added into foods may influence texture properties of product. In the study texture parameters of milk derived calcium complex enriched spreadable fat were measured using instrumental and sensory methods. Additionally overall sensory quality and chemical indicators i.e. peroxide value and acid value were estimated. All measurements were carried out during 3 months of storage. There was not significant influence of fortification on samples quality. Results of peroxide value measurements may suggest protective influence of added milk calcium complex against oxidation. The average daily portion of enriched spread (30 g) might provide at least 160 mg of best available calcium of milk origin, i.e. 15% of its recommended daily intake, which can significantly improve dietary calcium level.