Researches Concerning the Dynamics of some Biochemical Modifications in Pork during the Salting and Tendering Process

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1 Bulletin UASVM Agriculture, 66 (2)/2009 Print ISS ; Electronic ISS Researches Concerning the Dynamics of some Biochemical Modifications in Pork during the Salting and Tendering Process Claudiu-Dan SĂLĂGEA, Cornel LASLO, Dorin ŢIBULCĂ, Crina MUREŞA 1) University of Agricultural Sciences and Veterinary Medicine, Faculty of Agriculture, 3-5 Mănăştur Street, Cluj-apoca, Romania, Abstract. There have been organoleptically and physically-chemically examined twenty-five samples of pork semi-manufactured products (minced and salted pork, in different stages of tendering process) used in the manufacturing process of some meat products in casings. During the salting and tendering process we noticed a ph increase, and protein nitrogen decreases proportionally with the proteolytic degree, respectively, the degree of of meat. The quantity of water and nitrites decreases while salt content increases proportionally with the water content decrease. These values limit the period of the tendering process at maximum 72 hours, the optimum period being considered as 48 hours, the storage conditions being at Celsius degrees. Keywords: minced and salted pork, semi-manufactured products, physical-chemical quality indicators. ITRODUCTIO During the technological process for obtaining meat products, pork undergoes a series of physicochemical changes influenced by both the processing technology and the nature of meat used as raw material. Dynamics of biochemical changes of pork during the manufacturing process of various meat products has been one of the main concerns of researchers in this field. Thus, some authors (Banu, 1965, Briskey, 1961, Hamm, 1957) have studied the ph changes, the ability to retain water and potentially oxido-reduction in pork after the onset of muscle rigidity. Other researches (Stănescu, Laslo, 1971), regarding the biochemical changes during of meat, indicate an increase of free amino acids and non-protein nitrogen levels, in general. It has also been found an increase in hydro soluble nitrogen compounds and changes in taste and flavor. MATERIALS AD METHODS In assessing the quality of the pork semi-manufactured products used in the manufacturing process of certain assortments of meat products in casings, 25 samples of semi-manufactured products (minced and salted pork, sampled immediately after mincingsalting and after 24, 48, 72 and 96 tendering at Celsius degrees) were examined under the physical-chemical point of view (Tab. 1). 443

2 Meat semi-manufactured products and the number of examined samples Tab. 1 o. Product analysis umber of samples examined 1. Minced and salted pork 5 2. Minced pork, salted and aged for 24 hours 5 3. Minced pork, salted and aged for 48 hours 5 4. Minced pork, salted and aged for 72 hours 5 5. Minced pork, salted and aged for 96 hours 5 The physical-chemical examination aimed to determine the indicators presented in Tab. 2. Tab. 2 The physical-chemical quality indicators of semi-manufactured products samples o. Physical-chemical indicator Method of examination 1. Chemical reaction (ph) Potenţiometric (WTW ph-meter) (STAS , 1974) 2. Water, g% Drying-over at 105 Celsius degrees (Drying oven with thermoregulation) (STAS , 1973) 3. Total nitrogen, g% Kjeldahl method (Device for protein determination) 4. Protein substances, g% Kjeldahl method ( X 6.25) (STAS , 1981) 5. Amino nitrogen, mg% Sörensen-Gavrilov method (STAS 6513, 1978) 6. Ammonia nitrogen, mg% Distilling by oxide magnesium (STAS , 1974) 7. Total content in free aminoacids, mg/g proteins 8. Protein scission indices Quantitatively and qualitatively by gas chromatography (gas chromatography with mass spectrometer) H 100 H Fatty substances, g% Soxhlet extraction (Soxhlet device) (STAS , 1973) 10. Sodium chloride, % Mohr method (titration of Cl - and a + ions in the aqueous extract with a solution of AgO n in the presence of chromatic potassium used as an indicator) (STAS , 1973) 11. itrites, mg% Griess method (by UV-VIS spectrophotometer) (STAS , 1974) RESULTS AD DISCUSSIOS The results of organoleptic and physical-chemical exam of the semi-manufactured products (minced and salted pork, sampled immediately after mincing-salting respectively after 24, 48, 72 and 96 tendering at Celsius degrees) are presented in Tab. 3 and Tab. 4. Tab. 3 The dynamics of biochemical alterations during the pork salting and tendering process (medium values) (Sălăgean, 2006) o. Parameters investigated After mincingsalting ; After 24 3 After 48 After 72 After 96 x x x x x 1. ph Water, g% Total nitrogen, g% Protein substances, g% Amino nitrogen, mg% Ammonia nitrogen, mg%

3 7. 8. Total content in free aminoacids, mg/g proteins Protein scission indices: -H H Fatty substances, g% water proteins proteins lipids Sodium chloride, g% itrites, mg% The physical-chemical modifications of pork semi-manufactured products highlight, after pork mincing and salting (Tab. 3), an increase in ph from initial values of 5.80 to 6.30 after 96. Total nitrogen decreases during process of the coarse minced meat from 2.90 g% to 2.60 g%, at the end of the process. Parallel with the decrease of the nitrogen a decrease in the amount of protein substances, from the initial value of to g% (after 96 ), has been registered. Furthermore, as a result of proteolytic alterations occurring in meat during the process, an increase in amine nitrogen from 198 mg% to 280 mg% along with an increase of ammonia nitrogen from mg% to mg% and amino acid content from to mg/g protein) have also been registered. Indices of protein scission reveal an intense proteolytic activity during the of the coarse minced meat, registering increases from the value of 6.82 to in the case of amino nitrogen/ nitrogen index and the amount of 0.59 to 1.25 for ammonia nitrogen/ nitrogen index. The fat content, the water/proteins and protein/lipids ratios have been correlated with the meat quality and the other physical-chemical indicators. Thus, the fat content (g%) decreases from the average value of g% (after mincing-salting process) to the average value of g% (after 96 ), the water/proteins ratio increases from the average value of 3.52 (after mincing-salting) to the average value of 3.76 (after 96 ) and the proteins /lipids ratio decreases from the average value of 1.23 (after mincingsalting) to the average value of 1.11 (after 96 ). The sodium chloride content increases during the of the minced meat from the average value of 2.80 g% (after mincing-salting process) to an average of 4.00 g% (after 96 ), as a result of meat dehydration. The nitrites content registers a slight decrease from the average value of 4.50 g% (after mincing-salting process) to 3.50 g% (after 96 ), as a result of reducing processes under acidity, reducing substances and bacteria in meat. During the storage for, the free amino-acids content has registered a significant increase from the average mg/g proteins (after meat mincing and salting) to mg/g proteins (after 96 meat ) (Tab. 3). 445

4 The chromatographic analysis of the free amino-acids in the semi-manufactured products has set into evidence the same spectrum of amino-acids as that of the raw material meat, namely high quantities of glycine and aspartic acid, cystine, glutamic acid and serine, arginine, lysine, treonine and lower quantities of leucine+izoleucine, valine and phenylalanine; the rests of the amino-acids have been segregated in lower quantities, as can be seen in Tab. 4. Tab. 4 The free amino-acids content of the minced pork, salted and aged for 48 hours (mg /g proteins) (Sălăgean, 2006) r. crt. Aminoacidul x 1. Leucine + isoleucine Phenylalanine Valine Tyrosine Proline + alanine Treonine Glutamic acid + serine Glycine + aspartic acid Hystidine Arginine Lysine Cystine Total By correlating of the organoleptic characteristics of meat with the dynamics of some physical and chemical alterations during salting and tendering, one can observe, after 72 hours, an intense proteolytic activity reflected by the high values of some indicators such as: ph, amine nitrogen, ammonia nitrogen, the content of amino-acids, protein scission indices. COCLUSIOS The following conclusions ensue after the physical-chemical examinations regarding the quality of the pork semi-manufactured products (examined in different stages of salting and tendering process) used in the processing technology of the meat products: In the process of salting, meat undergoes changes in water content, ph, nitrogen, amino and ammonia nitrogen, amino-acids content, etc influenced, on one hand, by the nature of meat subjected to the salting process and on the other hand, by the salting process itself The semi-manufactured meat products during the curing and tendering process highlighted after 72 hours an intense proteolytic activity, reverberated in the high values of ph, amino nitrogen, ammoniac nitrogen, the content of amino-acids and of the protein scission indices. These values limit the period of the tendering process at maximum 72 hours, the optimum period being considered as 48 hours, the storage conditions being at Celsius degrees During the storage for of the meat, the free amino-acids content subscribe a significant increase, contributing to improving the flavor, taste, color and texture of semimanufactured products 446

5 The physical-chemical composition of the semi-manufactured products used in the processing technology of the meat products in casings has, besides the sensorial and hygienic characteristics and the technological factors, also a special importance in determining the quality of the finished products. REFERECES 1. Banu, C. and C. Cârâţă (1965). Food industry (in Romanian). 9: Briskey, E. H., J. Wismer-Pedersen. (1961). Journal of Food Science, 26(1): Hamm, R. (1957). Die Fleischwirt, 8: Sălăgean, C. D. (2006). Researches concerning the optimization of using protein derivates in the processing of meat products in casings and the quality of the obtained products, PhD Thesis, USAMV Cluj- apoca Stănescu, V. and C. Laslo (1971). Biochemical changes in beef and pork on the technological flow for the processing of meat, Scientific papers of I.A. Cluj, Veterinary Medicine Series, 27: *** STAS (1973) for determining moisture in meat and meat products 7. *** STAS (1973) for determining the fatty substances in meat and meat products 8. *** STAS (1973) for determination of sodium chloride in meat and meat products 9. *** STAS (1974) to determine the ph (chemical reaction) of meat and meat products 10.*** STAS (1974) to determine the ammonia nitrogen in meat and meat products 11. *** STAS (1974) for the determination of the nitrites in meat and meat products 12. *** STAS 6513 (1978) for the amine nitrogen in meat and meat products 13. *** STAS (1981) for determining protein substances 447