The aim of the study was to evaluate the post mortem proteolysis of centrifugal drip protein derived from pork. The varied course of the process of meat tenderization in muscles using the isoelectric focusing (IEF) technique was observed. The experimental material was the longissimus lumborum et thoracis muscle excised from 24 pigs of known origin, breeding and rearing conditions. Meat of normal quality (RFN) was examined in this study. On the basis of shear force values, the experimental muscles were divided into 4 groups of different courses of tenderization: A – meat remaining tough during the entire 6-day period of post-slaughter changes; B – meat characterized by a typical tenderization process, i.e. tough 48 h after slaughter and tender after 6 days of storage; C – tender or relatively tender meat on both dates of examination; D – meat which was the toughest 48 hours after slaughter and the most tender 144 hours after slaughter. Proteins for electrophoretic analysis on the agarose gel of the centrifugal drip fraction were submitted after 48 h and 144 h post mortem. The separation of the proteins was performed in a horizontal layout, using an FBE-3000 apparatus and an ECPS power pack (Pharmacia). On every path of the proteins separation, four ranges of pH value were evaluated, namely: 4.0 ÷ 6.0 pI, 6.1 ÷ 7.2 pI, 7.3 ÷ 7.7 pI and > 7.7 pI. Meat tenderness on the second day after slaughter was influenced by proteins, in which their pI was in the range of 6.1 ÷ 7.2 and 4.0 ÷ 6.0. From the evaluation which was carried out in the immunoblotting analysis of proteins using troponin T (9D) antibodies it was demonstrated that 48 h after slaughtering the most intense reactions were observed in the range of pI of 5.5 ÷ 5.9, which is the pH range corresponding to the isoelectric point of troponin T. However, after 144 h post mortem the most intense reaction was demonstrated in the range of pI of 6.1÷ 7.7. This indicates the breakdown of troponin T and an increase of the number of degradation products of this protein occurring while the meat tenderization process progresses. The degradation products of troponin T identified by IEF can be an indicator of meat tenderization.
Celem pracy było określenie wpływu dodatku mikrokapsułkowanego chlorku sodu, azotanu(III) sodu i kwasu mlekowego na stan mikrobiologiczny mięsa schabu i karkówki. Mięso przechowywano w warunkach chłodniczych (2 i 14 dób) i zamrażalniczych (3 i 9 miesięcy), po uprzednim umieszczeniu go w woreczkach z folii laminowanej PAPE, zamkniętych próżniowo. Z reguły stwierdzano istotnie wyższe zanieczyszczenie bakteriami tlenowymi mięsa karkówki w porównaniu ze schabem zarówno po 2, jak i po 14 dobach przechowywania w chłodni. Dodanie, oprócz soli, azotanu(III) sodu i kwasu mlekowego miało korzystny wpływ na trwałość mikrobiologiczną mięsa przechowywanego w chłodni przez okres 2 tygodni. Wydłużenie czasu zamrażalniczego przechowywania mięsa z 3 do 9 miesięcy powodowało redukcję liczby bakterii tlenowych w materiale zawierającym tylko sól, a wzrost bakterii zakwaszających, niezależnie od rodzaju stosowanej substancji dodatkowej. Przyczyniło się także do znacznej redukcji bakterii z grupy coli w mięsie schabu, czego nie zaobserwowano w przypadku karkówki. Użycie mikrokapsułkowanej soli nie stanowiło zagrożenia mikrobiologicznego mięsa nawet po 14 dniowym przechowywaniu.
Celem pracy było określenie zmian udziału białek w wycieku wirówkowym pozyskanym z mięsa buhajków czterech ras: polskiej holsztyńsko-fryzyjskiej (PHF) odmiany czarno-białej, polskiej czerwonej (PC), Limousine (L) i Hereford (H) ubijanych w wieku 6, 9 i 12 miesięcy, w ciągu 10-dniowego chłodniczego dojrzewania mięsa. Elektroforetyczną analizę białek wycieku wirówkowego pozyskanego z tkanki mięśniowej 45 min, 48, 96 i 240 h post mortem wykonywano techniką SDS-PAGE. Obecność titiny, desminy i troponiny T w wycieku wirówkowym potwierdzono metodą Western blotting z zastosowaniem monoklonalnych przeciwciał specyficznie rozpoznających określone białka. Stwierdzono, że czas dojrzewania był najważniejszym czynnikiem wpływającym na proteolizę białek mięsa. Największe zmiany w udziale białek o dużej masie cząsteczkowej (2400 ÷ 3700 kDa i >160 kDa) zaobserwowano po 10 dniach dojrzewania mięsa. W przypadku białek o mniejszej masie cząsteczkowej (160 kDa i 90 ÷ 95 kDa) zmiany te wystąpiły już w pierwszych dwóch dniach post mortem. Wszystkie analizowane czynniki zmienności, tj. rasa bydła, wiek buhajków i czas dojrzewania mięsa wpłynęły istotnie (p ≤ 0,05) tylko na udział białek o masie cząsteczkowej 90 ÷ 95 kDa. Najbardziej zaawansowany proces proteolizy białek wielkocząsteczkowych obserwowano w wycieku wirówkowym z mięsa buhajków rasy PHF.
There are different ways to define meat quality and various compounds may be employed as indicators of its quality. Progress observed in biological sciences, especially in proteomics, indicates that proteins building meat structures as well as those taking part in metabolic processes, by being a constituent part of enzymes, can provide indicators of meat quality. Meat quality, from the practical point of view, plays a particularly important role in the case of meat intended for culinary purposes. This study pays special attention to protein transformations associated with the most important meat properties, i.e. colour, water holding capacity/ juiciness and tenderness. It was indicated how, using tools of genomics and proteomics, it is possible to observe differences associated with quality. Special attention was paid to interconnections between oxidation processes and changes in meat colour and lipids but also protein transformations, including drip development.
Pigs, as husbandry animals, are very susceptible to stress, which in turn can influence their meat quality. Environmental factors present during breeding, transport and processing, influencing meat quality, are presented in this study along with results obtained by other authors. Most important factors are: environmental building conditions, level and system of feeding, transport conditions (type, distance, temperature), stunning, debleeding and handling of carcass after slaughter. In order to provide meat of highest quality to final consumers, in accordance with the latest normalization changes, it is essential to pay special attention to the whole set of environmental factors, embracing the entire production process (from breeding, transport, processing, distribution and sales).
The objective of this research was to evaluate the impact of different protective atmospheres, with or without the addition of lysozyme, which were used to pack swine longissimus muscles kept in cold store conditions for the period of up to 3 weeks. The employed atmospheres comprised: vacuum, modified atmosphere with carbon oxide (70% CO2, 29.5% N2, 0.5% CO) MAP-CO and with oxygen (79% N2, 20% CO2, 1% O2) MAP–O2. The evaluation of the shelf life of packed meat was performed on the basis of microbiological examination determining the total number of aerobic bacteria, Enterobacteriaceae family bacteria, enterococci as well as lactic acid bacteria (LAB). Measurements of hydrophobicity of muscle centrifugal drip protein were employed as a method allowing to compare the microbiological status of the meat during its storage in the chilled room. The atmospheres applied were found not to differ with regard to the degree of aerobic microorganisms development in the stored meat. The application of vacuum or MAP–O2 was found as a best way to inhibit the development of LAB. Samples with the addition of lysozyme were characterised by a slower development of microorganisms than these without its addition only in the case of samples packed in MAP–O2 and stored for 21 days. Storage time exerted a significant influence on the hydrophobicity of meat, which was lower in vacuum conditions than when protective gases were applied. The inclusion of lysozyme resulted in an increase of hydrophobicity.