Creatine and creatinine evolution during the processing of dry-cured ham

Dry-curing of ham involves many biochemical reactions that depend on the processing conditions. The aim of this study was to evaluate the effect of the dry-cured processing on the concentration of creatine, creatinine and the creatinine/creatine ratio. Dry-cured hams under study were salted using three different salt mixtures (100% NaCl; NaCl and KCl at 50% each; and 55% NaCl, 25% KCl, 15% CaCl₂ and 5% MgCl₂) in order to observe its influence on creatinine formation but no significant differences were found between them at any time of processing. However, significant differences between different post-salting times (20, 50 and 80 days) and the ripened hams (7, 9 and 11 months of ripening) were observed. Results showed that creatine and creatinine remain stable once the ripening period is reached. These results were confirmed when analysing dry-cured ham samples submitted to extreme conditions of temperature and time (20, 30, 40 and 70 °C during 0, 20, 40 and 60 min) as well as commercial dry-cured hams with more than 12 months of processing.     

Use of simultaneous brine thawing/salting in dry-cured Iberian ham production

The study of simultaneous brine thawing/salting as an alternative to the traditional stages in Iberian dry-cured ham processing was carried out employing 75 pre-cured frozen hams from Iberian pigs. The frozen hams were simultaneously thawed and salted with saturated brine for periods of 3, 5, and 7 days with and without the application of a vacuum pulse in order to reach the same salt concentration as the traditional procedure. The post-salting behaviour of the brine/thawed hams was also studied. The results obtained indicated that simultaneous thawing and salting would considerably reduce the time needed to reach the same salt concentration as with the traditional procedure (77% and 63% reduction with and without vacuum pulse, respectively). This also implied lower dehydration, so an increase in the post-salting time or in the weight lost during this stage is required.     

Biochemical and sensory changes in dry-cured ham salted with partial replacements of NaCl by other chloride salts

The reduction of the content of sodium chloride in dry-cured ham was studied in to prevent the problems related to high sodium intake (i.e. the hypertension). One of the possibilities to reduce the sodium content is the partial replacement of sodium chloride by mixtures of potassium, magnesium and calcium chloride salts. The effect of two salting formulations (formulation II: 50% NaCl-50% KCl and formulation III: 55% NaCl, 25% KCl, 15 CaCl₂ and 5 MgCl₂) on the protease activity through the dry-curing process and on the sensory characteristics of the final product was evaluated and compared to those of control hams (formulation I, 100% NaCl). Sensory attributes were all affected in the hams containing CaCl₂ and MgCl₂ while hams containing 50% KCl and NaCl (formulation II) were better valued, except for the attribute taste probably due to the potassium contribution to bitter taste.     

Accelerated processing of dry-cured ham. Part I. Viability of the use of brine thawing/salting operation

In a previous study, the brine thawing/salting operation using frozen hams as raw material was proposed in order to obtain accelerated processing of dry-cured hams. The time needed to reach the same NaCl concentration on a dry weight basis and the same NaCl concentration in the ham liquid phase for the deeper areas at the end of the post-salting stage were determined.

The aim of this work was to study the influence of the brine thawing/salting operation on the whole dry-cured ham manufacturing process, using the traditional thawing and salting methods as control.

The obtained results indicate that although a strong reduction in the thawing, salting and post-salting stages is obtained by using brine thawing/salting, the time needed in the dry-curing and maturing phases increases compared to those traditionally processed, probably due to the absence of pile salting and thus the reduction in the thickness of the ham piece as a consequence of the ham pressing. From the composition and microbiological point of view, no significant differences were observed among the hams processed by the different treatments.     

Nucleotides and their degradation products during processing of dry-cured ham, measured by HPLC and an enzyme sensor

The aim of this work was to study how nucleotide degradation during the processing of dry-cured ham is affected when using three types of salting (100% NaCl; 50% NaCl and 50% KCl; 55% NaCl, 25% KCl, 15% CaCl₂ and 5% MgCl₂). Divalent salts in the salting mixture depressed the breakdown rate from the beginning of the process (salting and post-salting) up to the ripening stage (7 months) when the inosine (Ino), hypoxanthine (Hx) and xanthine (X) concentrations matched for the three treatments. The evolution of Hx and Hx + X were analysed by HPLC and an enzyme sensor, respectively, during processing. Time and temperature conditions during the curing time did not affect Hx stability. The usefulness of the enzyme sensor was confirmed and it is a practical tool to determine Hx + X in dry-cured ham, as an index of minimum curing time. A good correlation between enzyme sensor and HPLC data was observed.     

Post-salting studies in Spanish cured ham manufacturing. Time reduction by using brine thawing-salting

The use of the simultaneous brine thawing/salting on frozen raw material was compared in a previous work with the traditional pile salting method. The aim of this study was to characterise and compare the post-salting stage in Spanish cured ham production by processing fresh and thawed raw material with the traditional pile salting method (which can be considered as the reference method), with the results obtained using the brine thawing/salting method, with and without applying vacuum impregnation. The obtained results show that the thawed salted hams exhibited a higher NaCl diffusion than the fresh ones, implying a shorter post-salting period. Post-salting stage could be reduced from the 50 days employed in the traditional fresh raw material salting, to 25 days when using frozen hams brine thawed/salted. No influence of the use of vacuum impregnation during the salting stage was observed on the post-salting period.     

The effect of NaCl-free processing and high pressure on the fate of Listeria monocytogenes and Salmonella on sliced smoked dry-cured ham

NaCl is an important multifunctional ingredient applied in dry-cured ham elaboration. However, its excessive intake has been linked to serious cardiovascular diseases causing a recent increase in the development of reduced salt products. In the present study Listeria monocytogenes and Salmonella, food-borne pathogens which can cross-contaminate post processed products, were spiked with < 100 CFU/g on slices of both standard (S) and NaCl-free processed (F) (elaborated with KCl + potassium lactate instead of NaCl) smoked dry-cured ham. Although L. monocytogenes and Salmonella counts decreased faster in S ham, pathogens were present in both types of non-pressure treated ham during the entire refrigerated storage period (112 days). Pressurisation at 600 MPa for 5 min caused the elimination of both pathogens in S ham after 14 days. In contrast, Salmonella and L. monocytogenes were present in F ham until days 28 and 56, respectively, indicating that the NaCl-free processed dry-cured ham had lower stability than standard smoked dry-cured ham.     

Effect of brine thawing/salting for time reduction in Spanish dry-cured ham manufacturing on proteolysis and lipolysis during salting and post-salting periods

The simultaneous brine thawing/salting operation has been proposed as an effective alternative for the accelerated processing of frozen cured hams. The aim of the present study was to study the effect of this new technology on the lipolytic and proteolytic enzymes responsible for the generation of flavour precursors during the salting and post-salting stages of the manufacturing of Spanish dry-cured ham. The effect of the frozen and thawed process produced a higher proteolytic and lipolytic activity than in the fresh traditional salted hams (FPS) that was detected by a higher concentration in free amino acids and free fatty acids. On the other hand, the brine thawed/salted treatments, at atmospheric pressure (BTS) and with vacuum impregnation (BTS-TP), produced an acceleration of the myofibrillar degradation that occurred in the BTS and BTS-TP hams in comparison to FPS. However, the lipolysis was affected by the frozen treatment but not by the brine thawed treatments, as few differences in free fatty acids and lipase activity were detected among the frozen and brine thawed hams at the end of post-salting stage.     

Evolution of nitrate and nitrite during the processing of dry-cured ham with partial replacement of NaCl by other chloride salts

Nitrate and nitrite are commonly added to dry-cured ham to provide protection against pathogen microorganisms, especially Clostridium botulinum. Both nitrate and nitrite were monitored with ion chromatography in dry-cured hams salted with different NaCl formulations (NaCl partially replaced by KCl and/or CaCl(2), and MgCl(2)). Nitrate, that is more stable than nitrite, diffuses into the ham and acts as a reservoir for nitrite generation. A correct nitrate and nitrite penetration was detected from the surface to the inner zones of the hams throughout its processing, independently of the salt formulation. Nitrate and nitrite achieved similar concentrations, around 37 and 2.2 ppm, respectively in the inner zones of the ham for the three assayed salt formulations at the end of the process, which are in compliance with European regulations.     

Proteolysis and sensory properties of dry-cured bacon as affected by the partial substitution of sodium chloride with potassium chloride

Quadriceps femoris muscle samples (48) from 24 pigs were processed into dry-cured bacon. This study investigated the influence of partial substitution of sodium chloride (NaCl) with potassium chloride (KCl) on proteolysis and sensory properties of dry-cured bacon. Three salt treatments were considered, namely, I (100% NaCl), II (60% NaCl, 40% KCl), and III (30% NaCl, 70% KCl). No significant differences were observed among treatments in the proteolysis, which was reflected by SDS–PAGE, proteolysis index, amino acid nitrogen, and peptide nitrogen contents. Furthermore, there were no significant differences in the moisture content between control and treatment II, whereas the moisture content in treatment III was significantly higher (p < 0.05) in comparison with control (treatment I). The sensory analysis indicated that it was possible to reduce NaCl by 40% without adverse effects on sensory properties, but 70% replacement of NaCl with KCl resulted in bacon with less hardness and saltiness and higher (p < 0.05) juiciness and bitterness.     

Study of salting and post-salting stages of fresh and thawed Iberian hams

Fresh raw material has been traditionally used to obtain dry-cured Iberian ham, although the use of thawed raw material is increasing. This type of raw material has been previously studied for dry-cured production employing White pigs, where the salting time has been reduced to reach similar NaCl concentrations. The aim of this work was the analysis of salting and post-salting stages of Iberian hams, employing fresh or thawed raw materials. The results showed that fresh Iberian hams had higher salt concentrations than thawed Iberian hams for the salting time ratio used, a ratio established to reduce the freezing/thawing effect that was previously observed working with White ham. This fact shows that the Iberian raw material in dry-cured ham manufacturing is less affected, by the freezing/thawing process than the White raw material.     

Characterisation of pile salting with sodium replaced mixtures of salts in dry-cured loin manufacture

Salting, one of the fundamental operations in Spanish cured loin manufacturing, is essential to preserve the product throughout its processing and storage. However, elevated blood pressure has been identified to be the major adverse effect associated with increased sodium intake. The partial replacement of NaCl with other chloride salts such as KCl, CaCl₂ and MgCl₂ has been proposed as a possible strategy to reduce the sodium content of these products. The aim of this study was to determine the salting time needed to reach the same chloride content as commercial dry-cured loins and, to characterise the first step in dry-cured loin production (salting), in loins salted with sodium partial replaced salts. The results indicated a reduction in the salting time when using KCl as NaCl substitute and an increase in the salting time when adding CaCl₂ and MgCl₂ to the mixture. Further studies need to be done in order to fully understand the influence of these low sodium mixtures of salts on the following manufacturing steps and the final quality characteristics of the product.     

Effects of potassium lactate and high pressure on transglutaminase restructured dry-cured hams with reduced salt content

Ten raw hams (from 5 carcasses) were boned and salted either with salt reduction (15 g/kg NaCl) or salt reduction with addition of potassium lactate (15 g/kg NaCl and 39.74 g/kg of a 60% K-lactate solution). Subsequently, the ham pieces were assembled together with transglutaminase, vacuum packed into water-permeable plastic bags and kept at 3 °C and 85% RH until reaching above 30% weight losses. The effects of K-lactate addition and the high-pressure (HP) treatment at 600 MPa on the physicochemical, instrumental colour and texture (Tensile test) and sensory characteristics of the biceps femoris (BF) muscle were evaluated. The addition of K-lactate did not have a negative effect on colour, flavour or texture of restructured dry-cured hams. The HP treatment increased significantly the pH, L^∗, a^∗ and b^∗ values and the breaking stress, and decreased the water-holding capacity and elasticity (apparent Young’s modulus) of BF muscle. The HP treatment also affected significantly the flavour (increasing saltiness, umami and sweetness) and the sensory texture attributes (increasing muscle binding, hardness, gumminess and fibrousness and decreasing adhesiveness and pastiness), as well as slice appearance (increasing brightness and iridescence and decreasing colour homogeneity).     

Processing of dry-cured ham in a reduced-oxygen atmosphere: Effects on physicochemical and microbiological parameters and mite growth

The effects of a reduced-oxygen atmosphere (ROA) ([O₂] < 4.5%) during part or the whole of dry-cured ham processing on microbiological and physico-chemical parameters and mite growth were investigated in two independent experiments. In Experiment 1, six hams were processed in ROA and six in air for 275 days; in Experiment 2, where lower RH was used, six hams were processed in ROA for 289 days, six for 214 days in air + 75 days in ROA, and six in air for 289 days. Microbiological analyses during the process and physicochemical analyses in final products were carried out. The use of ROA during the whole process increased the L∗ colour parameter in the subcutaneous fat and proteolysis index and decreased b∗ in the external part of the subcutaneous fat and cholesterol oxide concentration. The use of ROA combined with low RH retarded microbial growth and prevented mite growth.     

Carcass and ham quality characteristics of heavy pigs from different genetic groups intended for the production of dry-cured hams

Carcass and ham quality characteristics of pig populations divided by harvest weights — HW (130 and 160 kg) were evaluated to determine the effects of gender (barrows and gilts) and distinct genetic groups — purebred (DUDU) and crossbred Duroc (DULA, DUWI and DULL) as well as purebred Large White (WIWI) on the suitability for use in dry-cured ham production. At 130 kg, DUDU pigs yielded the highest fat thickness of the ham (P < 0.01) and an intramuscular fat content (IMF) of 3.15% in Semimembranosus muscle (SM). DUDU pigs also had a SM pH_u of 5.7. This genetic group met the specifications for dry-cured ham production. No differences could be found in meat quality characteristics between genetic groups harvested at 160 kg. However at this HW, gilts produced significantly (P < 0.05) heavier and leaner hams compared to barrows.     

Vitamin (B1, B2, B3 and B6) content and oxidative stability of Gastrocnemius muscle from dry-cured hams elaborated with different nitrifying salt contents and by two ageing times

The effect of the amount of added nitrate and nitrate plus nitrite to dry-cured hams on the vitamin (B1, B2, B3, B6) content, the antioxidant enzyme superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSHPx) activities and the thiobarbituric acid reactive substances (TBARS) was assessed in Gastrocnemius muscle at the end of two ripening processes. Five different curing mixtures (Hi–N: 600 KNO₃; Lo–N: 150 KNO₃; Hi–Mix: 600 KNO₃ + 600 NaNO₂; Lo–Mix: 150 KNO₃ + 150 NaNO₂; Hi–Mix/Asc: 600 KNO₃ + 600 NaNO₂ + 500 sodium ascorbate, expressed as mg of salts added on surface per kg of fresh ham) were evaluated in dry-cured hams aged for 11.5 months (standard process, SP) and 22 months (long process, LP).     

KCI in Dry Cured Hams: Effect on Trichinae Devitalization and Chemical and Physical Properties

Thirty trichina-infected hams were dry-cured under laboratory conditions for 62 and 69 days using three curing formulations which included the partial (0%, 25% and SO%) substitution of NaCl by KCI. Each treatment rendered the product free of viable trichinae. Sixty commercial hams were processed at a dry-cured ham plant. A high incidence of spoilage (62%) was observed among hams commercially processed. The degree of spoilage appears to be associated with the final sodium plus potassium content of the product. This study suggests that potassium cnhanccs the absorption of curing ingredients thus providing better protection against spoilage microflora. Under minimal processing conditions. both NaCl and KCI have essentially the same ability to devitalize trichinae in drp-cured hams.     

Use of computed tomography to study raw ham properties and predict salt content and distribution during dry-cured ham production

Varying salt content in hams of equal brand is a major challenge for Norwegian dry-cured ham producers. This study was thus undertaken to test existing computed tomography (CT) calibration models for salt on entire hams, regarding predictability of salt content at different processing times including final ham and to study salt distribution during processing of dry-cured ham. Twenty-six hams were scanned by computed tomography (CT) 11 times during dry-curing for this purpose. However, previously established calibration models had to be adjusted as they overestimated salt in dry samples. Prediction of ultimate salt content was more accurate approaching the end of the dry-curing process (RMSEP = 0.351-0.595% salt). Inclusion of remaining weight loss improved the prediction accuracy in un-dried samples by approximately 0.1% NaCl. The prediction errors were sufficiently low to be of practical interest.     

A note on the relationships between cured-cooked and dry-cured ham processing yields

Right and left hams from 353 pigs slaughtered at around 100 kg body weight were processed into cured-cooked hams and dry-cured hams, respectively. Weights and yields at various stages of each process, carcass lean content and fresh meat quality traits were registered. Technological yield of cured-cooked processing (saleable cooked ham weight/defatted–deboned fresh ham weight) was more closely correlated to ultimate pH (r = 0.51, p < 0.001) than to carcass leanness (r = −0.13, p < 0.05) whereas the reverse situation – r = 0.15 (p < 0.01) and r = −0.62 (p < 0.001), respectively – was found for technological yield of dry-cured processing (saleable dry ham weight/trimmed fresh ham weight). The correlation between the two technological yields was significantly positive but of fairly moderate magnitude (r = 0.36). The correlation between the overall yields (saleable processed ham weight/entire fresh ham weight) of the two processes revealed to be very close to zero (r = −0.01).     

Changes of free amino acids and biogenic amines during extended ageing of Italian dry-cured ham

Sixty-two fresh hams were sub-grouped to undergo different processing times (15, 19 and 23 months), and corresponding dry-cured hams were analysed for changes in moisture, protein, NaCl, pH, proteolysis, free amino acids (FAAs) and biogenic amines (BAs) as related to the extended ageing. Dry-cured hams were influenced by ageing time, showing a decrease in moisture and water activity and an increase in pH, nonprotein nitrogen (NPN) and FAAs in more aged samples. The increase in FAAs and BAs progressively observed until the last sampling time might be enhanced by the moderate salt content (≈5 g NaCl/100 g muscle) and relatively high a_w (>0.90) of dried hams even at 23 months of processing. Among FAAs, arginine did not increase with ageing, which might be due to arginine hydrolysis to ammonia and ornithine, followed by decarboxylation to putrescine, i.e. molecules largely present in the more aged hams. Tyramine, the most abundant among BAs, putrescine and cadaverine showed a dependence on time and proteolysis indices (NPN and FAAs). In this respect, the practice of extending the standard ageing time of typical italian dry-cured ham (13-15 months), regarded as a tool for improving sensory property of this product, should be supported by further studies, mainly at the manufacturing level, to minimize FAA and BA generation.