Effect of brine thawing/salting on endogenous enzyme activity and sensory quality of Iberian dry-cured ham

Simultaneous brine thawing/salting process was applied as an alternative to traditional pile salting process using 51 frozen Iberian hams. The effect of this type of salting process on endogenous enzyme activity and sensory quality of Iberian dry-cured hams was analysed. The frozen hams were simultaneously thawed and salted with saturated brine, with and without vacuum pulses, and were compared to hams thawed under refrigeration and traditionally salted. The peptidase and lipase activities were measured at the end of salting and post-salting stages. The activity of cathepsin B+L was reduced in the two brine salted batches while few differences among batches were observed for the other peptidases. Several lipase activities were significantly reduced in the two brine salted batches. The brine thawed processing affected the free fatty acid content at the different stages although the differences were more appreciated at the beginning of the process and no differences were observed at the end. The long ripening time makes these differences negligible and the consumer did not appreciate any differences between the sensory quality of Iberian brine/thawed hams and traditional Iberian thawed pile salted hams.     

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.     

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.     

Effect of prefreezing hams on endogenous enzyme activity during the processing of Iberian dry-cured hams

The use of frozen/thawed raw material in the processing of Iberian dry-cured ham has been studied to determine its effect on the sensory quality of the final product. The proteolysis and lipolysis processes were measured by the proteolytic and lipolytic enzyme activities and free amino acids and free fatty acids. The thawed Iberian hams had lower salt contents throughout the process. The use of thawing raw material did not affect the proteolytic enzymes, cathepsins, aminopeptidases and dipeptidylpeptidases, only the activity of dipeptidylpeptidase III was reduced due to thawing. Moreover, there were no differences in the content of free amino acids between fresh and thawed hams during the whole process. However, the use of thawing hams affected the lipolytic activity. The activity of phospholipase and neutral lipase were significantly higher in the thawed hams and also the content of free fatty acids, at all the stages analyzed. Consumer sensory analysis showed thawed Iberian hams had the lowest hardness, probably due to an intense proteolysis. The acceptability of the Iberian hams was similar between fresh and thawed hams.     

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.     

Frozen herring as raw material for spice‐salting

One batch of herring (Clupea harengus) was spice‐salted fresh and as thawed after 32 days of frozen storage at −24 °C. After salting, samples of both groups were sent to participating laboratories in Iceland, Denmark, Norway, Germany and England. The herring was kept at 5 ± 1 °C and sampled three times during a 26 week storage period. The development of taste and texture characteristics (determined by sensory evaluation and instrumental texture measurements), formation of low‐molecular‐weight nitrogen compounds and changes in proteolytic activity were followed in both groups. The sensory evaluation results showed that thawed salted herring ripened in a similar manner to herring salted fresh, but at a faster rate. Instrumental texture analysis showed a faster rate of tenderising in thawed salted herring. Proteolytic activity measured as general activity and with specific synthetic substrates was higher in the thawed salted herring. The formation of trichloroacetic acid‐soluble nitrogen and free amino acids was faster in the previously frozen herring. The results show an accelerated but similar rate of ripening in thawed spice‐salted herring in comparison with fresh salted herring. © 2000 Society of Chemical Industry     

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.     

Lipolytic and proteolytic properties of dry-cured boneless hams ripened in modified atmospheres

We studied proteolytic and lipolytic properties of dry-cured boneless ham (porcine quadriceps femoris) made with chilled (10°C, 48 h) or frozen/thawed meat (frozen at -20°C frozen for 90 days and followed by thawing at 10°C for 48 h) were determined. Dry-cured meats were stored in modified atmosphere packages (100% N(2) and a mixture of 75% N(2)+25% CO(2)) at 15°C with the intention of reducing ripening space. Results showed that dry-cured hams made with frozen/thawed raw meat had more salt, volatile fatty acids and free fatty acid content after salting and smoking. Whereas, samples prepared with chilled meats contained more nitrogenous compounds (water-soluble nitrogen, non-protein nitrogen, and free amino acids). Volatile and free fatty acid contents in all samples significantly increased with storage. Acetic acid was the predominant volatile fatty acid. To confirm lipolytic activity in dry-cured ham stored in modified atmospheres, we calculated the lipolytic coefficient. The lipolytic coefficients of all samples were positive values and significantly (P<0.05) increased with storage indicating lipolysis in samples were still active. Furthermore, nitrogenous compounds in dry-cured ham significantly (P<0.05) increased with storage indicating proteolysis in samples were not affected by modified atmosphere storage. Aerobic, anaerobic and lactic acid bacteria counts in dry-cured meats were stable to modified atmospheres storage for 20 weeks at 15°C. Flavor, texture and color score in sensory evaluation for dry-cured ham made with chilled meat were significantly higher than that made with frozen/thawed meat. All samples had high overall acceptance scores in sensory evaluation. Results in this study suggested that dry-cured boneless ham stored in modified atmospheres for 20 weeks at 15°C was another feasibility to ripen the meat without affecting lipolysis, proteolysis, microbiology and sensory quality.     

Accelerated processing of dry-cured ham. Part 2. Influence of brine thawing/salting operation on proteolysis and sensory acceptability

In a previous study, the brine thawing/salting operation using frozen hams as raw material was studied as a valid alternative for the accelerated processing of dry-cured hams. But no information was available on how this treatment could affect some important biochemical mechanisms and the sensory quality of hams. The aim of this work was to study the influence of the simultaneous brine thawing/salting operation on proteolysis and sensory acceptability of the produced dry-cured hams. The results confirm that dry-cured hams can be produced by using brine thawing/salting with a substantial reduction in the thawing and salting time needed. This accelerated process resulted in similar or even better sensory preferences than hams produced through the traditional method. However, the preference of consumers based on the appearance was lower for most of the hams than when using the traditional method, probably due to a wider slice section of the brined hams that can be corrected by adequate pressure during the salting. Thus, this treatment can be used without affecting the quality of dry-cured hams.     

Lipolysis and proteolysis in Ragusano cheese during brine salting at different temperatures

The influence of temperature (12, 15, 18, 21, and 24 degrees C) of saturated brine on lipolysis and proteolysis in 3.8-kg blocks of Ragusano cheese during 24 d of brining was determined. Twenty-six 3.8-kg blocks were made on each day. The cheese making was replicated on 3 different days. All blocks were labeled and weighed prior to brining. One block was sampled and analyzed prior to brine salting. Five blocks were placed into each of 5 different brine tanks at different temperatures. One block was removed from each brine tank after 1, 4, 8, 16, and 24 d of brining, weighed, sampled, and analyzed. Both proteolysis and lipolysis in Ragusano cheese increased with increasing brine temperature (from 12 to 24 degrees C), with the impact of brine temperature on proteolysis and lipolysis becoming progressively larger. Proteolysis was highest in the interior of the blocks where salt in moisture content was lowest and temperature had more impact on proteolysis in the interior position of the block than the exterior position. However, the opposite was true for lipolysis. The total free fatty acid content was higher and temperature had more impact on lipolysis at the exterior position of the block where salt in moisture was the highest. This effect of increased salt concentration on lipolysis was confirmed with direct salted cheeses in a small follow-up experiment. Lipolysis increased with increasing salt in the moisture content of the direct salted cheeses. It is likely that migration of water-soluble FFA from the brine into the cheese and from the interior portion of the cheese to the exterior portion of the cheese also contributed to a higher level of FFA at the exterior portion of the blocks. As brine temperature increased the profile of individual free fatty acids released from triglycerides changed, with the proportion of short-chain free fatty acids increasing with increasing brine temperature. This effect was largest at high salt in moisture content.     

Influence of pre-cure freezing of Iberian hams on lipolytic changes and lipid oxidation

The purpose of this work was to study the influence of pre-cure freezing of Iberian hams on lipolysis and lipid oxidation during the ripening of the product. At the green stage, the levels of fatty acids (FA) in the free fatty acids fraction were higher in pre-cure frozen (F) than in refrigerated (R) hams, whereas in the polar lipid fraction, FA and dimethyl acetals (DMA) values were higher in R than in F Iberian hams. These results point out the existence of lipolysis phenomena during the freezing storage. At the end of post-salting and at the final stage, both R and F hams showed similar FA and DMA profiles. The effect of pre-cure freezing of hams influenced lipolysis evolution throughout the processing. The development of lipid oxidation was similar in R and F hams, but Thiobarbituric acid-reactive substances (TBAR) values were significantly higher in F hams at the initial stage and at the end of post-salting and drying steps. Despite all these differences, at final stage the FA and DMA composition as well as TBAR levels were quite similar in R and F hams.     

Free fatty acid content of Manchego-type cheese salted by brine vacuum impregnation

A new salting method based on the brine vacuum impregnation of porous products was tested in Manchego-type cheese in order to assess its effect on cheese lipolysis during ripening. This new salting method would allow a faster salt diffusion and a more homogeneous initial salt distribution, and would reduce the disposal of brine. Salt-in-moisture content was evaluated in three different cheese zones during a 90-day ripening period in order to monitor salt penetration in the cheese. Lipolysis was evaluated by means of gas chromatography of individual free fatty acids in the medium and internal zones of both cheeses salted by the conventional and the new salting procedures. Free fatty acid concentration regularly increased during ripening. Short-chain free fatty acid content was higher in the internal zone of conventionally salted cheeses than in the internal and medium zones of vacuum impregnated cheeses from the first month after manufacturing, probably due to the low initial salt concentration achieved in the inner zone of conventionally salted cheeses, which can enhance both bacterial and indigenous lipase activity. Panelists considered that conventionally salted cheeses presented a more intense aroma than vacuum impregnated cheeses, though no differences in global flavor intensity were observed.     

Influence of salting procedure on the composition of Muenster-type cheese

Muenster-type cheeses were salted with a traditional saturated brine solution or by direct addition of salt to the curd. Cheeses were evaluated at 0, 30, 60, 90, 120, and 180 d of age for numbers and type of microflora, casein hydrolysis, and amounts of free fatty acids. No significant differences were found in the populations of starter, lactobacilli, or yeast for the brine- and direct-salted cheeses. The amounts of free fatty acids liberated were similar for both cheeses. The hydrolysis of alpha s1-casein was complete at 90 d of age, whereas only 40% of the beta-casein was hydrolyzed at 180 d of age. The inner layer of the brine-salted cheeses had the highest number of starter microorganisms, followed by the middle and outer layers, respectively. The salt concentrations were similar in the three layers after 4 mo of age. Results of this study showed that comparable Muenster-type cheese could be produced with either of the salting procedures. With direct salt addition to curd, a 59% reduction was observed in salt emissions from the Muenster manufacturing process.     

Reducing salt content of dry-cured ham: effect on lipid composition and sensory attributes

The salt content of dry-cured ham must be reduced to adapt the product to the taste of the consumer and to human health recommendations. This study dealt with the effect of lowering salt content on the lipid composition and sensory attributes of 18-month-old Corsican dry-cured hams. Six were salted according to a long time salting method and six according to a short time method (STS). The latter was lower in both total and free chlorides (4.7% v 7.3% and 1.5% v 2.0%, respectively) and in dry matter (23.8% v 25.2%). The composition of the intramuscular lipids was similar for both salting methods except that the proportion of polyunsaturated fatty acids of the phospholipids was higher in STS hams (42.3% v 34.0%). The salting method had no significant effect on the appearance of the hams (marbling, colour). However, the STS hams were less salty and their aroma notes related to fat such as rancid, fatty and buttery were more pronounced.     

Influence of process temperature and salting methods on starter and NSLAB growth and enzymatic activity during the ripening of cheeses produced with Streptococcus thermophilus and Lactobacillus helveticus

The effect of varying cook temperature (40 or 50 °C) and salting method (dry or brine salting) on bacterial viability, enzymatic activity and chemical composition in cheeses made using Streptococcus thermophilus and Lactobacillus helveticus were investigated. Dry salting resulted in decreased cell viability of L. helveticus, increased lactate dehydrogenase activity and increased free amino acid levels, compared with brine salted cheeses, irrespective of cook temperature. A cook temperature of 50 °C resulted in reduced primary proteolysis and increased pH in comparison with that in cheeses cooked to 40 °C. Salting method influenced moisture content with higher levels in brine salted cheeses; cook temperature was also influential with higher cook temperature resulting in lower moisture within each salting method. Variations in manufacture procedure can allow for the development of cheese varieties with novel flavour and texture profiles using existing Cheddar or Swiss-style manufacturing facilities.     

Effect of pH at time of salting on the functional properties of pre-rigor beef

The functional properties of thawed pre-rigor beef that had been minced and salted or not salted when its pH value reached 6.8, 6.6, 6.4, 6.2 and 6.0, then immediately frozen, were determined. The mince samples were used to manufacture a finely comminuted sausage batter. Presalting before frozen storage resulted in higher (p < 0.05) thawed mince pH, and batter cook yield and shear strain, and lower (p < 0.05) mince salt soluble proteins, thaw drip and Hunter L^* and b^* values and batter shear stress than unsalted controls. The pre-rigor pH at time of salting/mincing affected (p < 0.05) thaw drip (unsalted mince only), Hunter L^* and b^* values and shear stress. Shear stress tended to increase (p < 0.01) and Hunter L^* (p < 0.05) and b^* (p < 0.01) values tended to decrease with fall in pre-rigor salting pH. No interaction (p > 0.05) between salting and pre-rigor pH at time of salting was observed.     

腌制对鸭蛋中油脂品质的影响

以新鲜鸭蛋为原料,采用裹蛋腌制法制备咸鸭蛋。研究了腌制过程中不同腌制时间对咸鸭蛋的蛋黄指数、水分含量,以及对蛋黄油皂化值、酸值、胆固醇含量、脂肪酸构成等指标的影响。研究结果表明,随着腌制时间的延长,鸭蛋中的水分含量逐渐降低,而蛋黄指数、蛋黄油皂化值、酸值、胆固醇含量逐渐增加。腌制后的鸭蛋中不饱和脂肪酸含量略有降低,而饱和脂肪酸和反式脂肪酸含量略有增加。总体而言,腌制并没有鸭蛋中蛋黄油的食用品质产生严重的影响。     

Evolution of volatile aldehydes in Iberian ham matured under different processing conditions

To evaluate the influence of the Iberian ham processing conditions in the evolution of volatile aldehydes, 35 hams were processed in two plants following different conditions of relative humidity and temperature. For this, free fatty acids, peroxide values and volatile aldehydes were quantified in the hams. The highest increases in free fatty acids were noted during the drying stage in both processing plants. The drying period also revealed the greatest increase in peroxide values, where the highest values were in those hams processed at higher temperatures. The temperature during post-salting and drying had a marked influence on the formation of volatile aldehydes, being responsible for the differences in volatile compounds of matured hams.     

Quantification and kinetics of the residual brine generation during ham and shoulder pile salting

Salting is one of the most important stages of the traditional process of cured ham manufacturing. During pile salting a saturated brine is formed and drips through the orifices located at the bottom of the salting containers.

The objective of the present work was to quantify the released brine in the ham manufacturing industry in Spain and to relate the brine generation with the salt gained by hams in the process.

The total released brine during ham and shoulder salting in Spain was determined theoretically and from the experimental values obtained from the industry (around 38,000 metric tons in 2002). In addition to that, an easy method for the estimation of the NaCl gained by hams and shoulders was developed by using the measurements of the released brine (the estimated NaCl gained differed 3.5% from the experimental data).     

腌制过程咸蛋黄的脂质特性研究

经过食盐的腌制作用,鸭蛋黄出现了明显的出油和固化现象,蛋黄脂质发生了微弱的氧化。共轭二烯酸(CDA)含量在第7周达到最大值0.21%,随后下降,而游离脂肪酸(FFA)含量在第11周出现最大值3.4%。经脂肪酸的气相色谱-质谱(GC-MS)分析发现,腌制后咸蛋黄与新鲜蛋黄脂肪酸的组成含量差异不明显。新鲜蛋黄和咸蛋黄中同时发现一定含量的对人体有益的脂肪酸,如共轭亚油酸和花生四烯酸。新鲜蛋黄和咸蛋黄均含有大量不饱和脂肪酸,含量约为67.8%。