José Flores

Muscle lipolysis phenomena in the processing of dry-cured ham

Abstract Muscle lipases and esterases were assayed for activity at different stages (0–15 months) in the processing of dry-cured hams. The evolution of volatile and nonvolatile free fatty acids, during processing, was also determined. All the assayed enzymes were found to be quite stable and active even after 15 months of processing. Most lipolysis seemed to occur during the first 5 months when maximal generation of free fatty acids was detected. Neutral and basic lipases are more active at the beginning of the process, while lysosomal acid lipases are active through the entire process. These enzymes seem to be the main ones responsible for the observed lipolysis. Muscle esterases showed excellent stability, but the amounts of volatile free fatty acids were very low, suggesting only a minor role for these enzymes. The study indicates that lipolysis plays a role in the ripening of Spanish dry-cured ham.

Activities of pork muscle proteases in model cured meat systems.

The effect of curing agents (salt, nitrate, ascorbic acid and glucose) and processing parameters (pH, water activity and drying and cooking temperatures) on pork muscle cathepsins B, D, H and L as well as leucyl, arginyl and tyrosyl hydrolysing activities is reported. Salt (60 g/l) showed a powerful inhibitory effect, especially on cathepsin D and aminopeptidase activities where less than 13% of the original activity was recovered. Cathepsin H was also affected (38% of the original activity) while cathepsins B and B+L recovered 72.5 and 63.0%, respectively. Nitrate (0.2-0.25 g/l) and ascorbic acid (0.2-0.4 g/l) did not significantly affect the enzyme activities. On the other hand, 0.5-2 g/l of glucose activated both cathepsins B and D with an increase of 39.5 and 28.5% and also leucyl and arginyl hydrolysing activities which were 75.0 and 24.0%, respectively. No aminopeptidase activity was detected when assayed in 100 mM sodium citrate buffer, pH 5.1. Cathepsin H was also very affected at that pH and only 12.0% of activity was recovered. A decrease in water activity, especially below 0.84, also affected the enzyme activities which were found below 50%. Temperatures in the usual range of the drying process (22 and 30 degrees C) gave substantial enzyme activities (around 40-50 and 80%, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Characterization of green hams from Iberian pigs by fast analysis of subcutaneous fat.

Melting point, slip point, iodine value (fast analyses) and percentage contents of fatty acids were determined in subcutaneous fat of hams from Iberian pigs in order to study the possibilities of characterizing the type of pig feeding and the relationships between the results of fast analysis and fatty acid contents. Both types of analyses showed important differences between samples from pigs fed on acorn and samples from pigs fed on mixed feeds. When a combination of feeding materials (acorn and mixed feeds) was used, the analyses gave intermediate results, closer to those obtained with mixed feeds only. On the other hand, generally high simple and multiple correlation coefficients (greater than 0·85) were obtained between fast analyses and fatty acid contents, which allows accurate predictions using regression and canonical correlation analyses.

Effect of nitrate and nitrite curing salts on microbial changes and sensory quality of non-fermented sausages

The effects of nitrate and nitrite curing salts on microbial changes and sensory quality of non-fermented sausages of small diameter were investigated. During pre-ripening (day 5), levels of lactic acid bacteria and yeasts were slightly higher in nitrite-made sausages than in those made with nitrate. In contrast, nitrite discouraged the growth of psychrotrophs as occurs in fermented sausages. By the end of ripening (day 26), levels of microorganisms were similar in both batches of sausages except for psychrotrophs being higher in those made with nitrite. Nitrate-made sausages showed higher aroma and taste intensity.

Mediterranean vs northern European meat products. Processing technologies and main differences

Abstract The European Union (EU) meat industry mainly focuses its activity around the curing of pig meat. In Mediterranean countries the term ‘cured’ is usually applied to products which have undergone a long process of ripening, while in northern Europe products treated with nitrites are considered cured, although there are subtle differences which depend on the process of ripening. In this work the technological processes of curing normally used in the EU are described as a base for discussing the differences that exist between the techniques followed in the north of Europe and the Mediteranean region, and which perceptibly affect the sensorial characteristics of the products. The main differences are centered around dry-cured products, principally because of the diverse methods of curing and smoking in which concepts of preserving and the development of flavour are intimately connected. In the north of Europe, nitrite is used and smoking is considered an integral part of the curing process; in the Mediterranean regions nitrate and long ripening processes are used instead, and these differences are manifest in the sensorial characteristics of the products. Up to now, research has mainly focused around the effects of salt and nitrite as responsible agents in the development of cured meat flavour. Little attention has been paid to the effects of other components, like nitrate, and the microbial and muscular enzymatic systems, which constitute the flavour of dry-cured products. Therefore, further studies are required to evaluate the many factors that may contribute to the formation and differentiation of cured and dry-cured meat flavours.

Protein extractability in dry-cured ham

Abstract Different procedures for the extraction of myofibrillar and total proteins of both raw and dry-cured ham have been assayed. Three solvents—(1) 0.1 m phosphate buffer + 1.1 m KI, pH = 7.4 , (2) 0.1 m tris/HCl + 1 % ( w/v ) sodium dodecyl sulphate, pH = 7.0 and (3) 8 m urea + 1 % ( v/v ) β-mercaptoethanol-were used for myofibrillar proteins extraction and the homogenates compared quantitatively and by electrophoresis. Solvent (3) gave a higher protein recovery from dry-cured ham than solvent (2) although the electrophoretic patterns showed similar profiles. One relevant fact was the appearance of a 150 KDa fragment and numerous fragments in the 50–100 KDa region. No myosin band was observed.

Effect of dry-curing process parameters on pork muscle cathepsin B, H and L activity

ZusammenfassungEs wird die Wirkung von Salz, Nitrat, Ascorbinsäure und Glucose sowie die Wasseraktivität, pH und Temperatur auf die Wirksamkeit der Kathepsine B, H und L des Schweinefleisches untersucht. Das Salz hemmt das Kathepsin H sehr stark, denn nur 40–50% der ursprünglichen Aktivität wurde in Anwesenheit von 4–5% Salz erreicht, was typisch für ein Pökelmilieu ist, während die Kathepsine B und L weniger beeinflußt werden und ca. 65–75% der ursprünglichen Wirksamkeit wieder erlangen. Die Ascorbinsäure (1 g/L Lösung) hindert sehr stark das Kathepsin H, während die Glucose (über 2 g/L Lösung) zu ca. 30% das Kathepsin B fördert. Die Enzymtätigkeit wird vom Nitrat nicht beeinflußt. Bei abnehmen der Wasseraktivität werden die Aktivitäten der Kathepsine B und H reduziert, wobei letztere jegliche Aktivität bei einem pH-Wert unter 5,5 verliert, ein beim Reifen der Wurstwaren üblicher Wert. Die drei Enzyme waren sehr aktiv bei Temperaturen zwischen 20 °C–30 °C. Eine Untersuchung „in vitro“ mit den drei Phasen des Reifens offenbart, daß die Kathepsine B und L insgesamt eine wichtige Rolle spielen, wohingegen das Kathepsin H nur ab Mitte des Pökelvorganges wirksam ist.SummaryThe effect of chemical agents (salt, nitrate, ascorbic acid and glucose), and process parameters (water activity, pH and temperature) on porcine muscle cathepsins B, H and L was studied. Salt strongly inhibited cathepsin H activity. Only 40–50% of the original activity was recovered in the presence of 4–5% salt, typical of dry-cured meat products, while cathepsins B and L were less affected, recovering around 65–75% of their original activity. Ascorbic acid (above 1 g/L) strongly inhibited cathepsin H whereas glucose (up to 2 g/L) activated (around 30%) cathepsin B. Nitrate did not affect cathepsin activity. A decrease in water activity affected cathepsin B and H activity and cathepsin H activity was almost negligible below pH 5.5, which is usual in dry-cured sausage processes. All three enzymes were very active in the temperature range, 20–30° C, typical of dry-curing processes. A study in vitro, representing three stages of the dry-curing process of hams, revealed that cathepsins B and L might play an important role throughout the complete process whereas cathepsin H only participated in the middle and at the end of the dry-curing.

Sensory improvement of dry-fermented sausages by the addition of cell-free extracts from Debaryomyces hansenii and Lactobacillus sakei

The effects of the addition of a combined cell-free extract from Lactobacillus sakei and Debaryomyces hansenii (D+L) or just a D. hansenii cell-free extract (D) to the initial formulation of a dry-fermented sausage were evaluated. The differences found among batches in the main microbial populations, pH, moisture content and global proteolytic and lipolytic indexes (total free amino acids, non protein nitrogen, acidity and tiobarbituric acid index) were not significant. Only, the acidity value of batch D was significantly higher (p<0.05) than that of batch D+L. Thus, cell-free extract from D. hansenii accelerated the lipolysis. Moreover, there were some significant differences (p<0.05) in the amino acid profile and, especially, in the aroma profile. The combination D+L and D promoted the generation of volatile compounds derived from lipid oxidation and carbohydrate fermentation. In batch D, the production of volatile compounds derived from amino acid catabolism and microbial fermentation was also enhanced. The overall quality was improved by both treatments (D+L, D) and also the aroma by addition of the combination of extracts (D+L). It is concluded that the addition of cell-free extracts from D. hansenii and, particularly, D. hansenii plus L. sakei could be useful to improve the final quality of fermented sausages.

Activity of cathepsin D as affected by chemical and physical dry-curing parameters

ZusammenfassungDie Wirkung von Pökelhilfsstoffen (Nitrat, Glucose, Ascorbinsäure und Chlorid) und physikalischen Parametern (Temperatur, Wasseraktivität und Druck) auf Kathepsin D aus Schweinemuskeln wurde untersucht. Chlorid zeigte einen starken Hemmeffekt. Nitrat und hohe Konzentrationen von Ascorbinsäure (von 4 bis 8 g/L) hemmen Kathepsin D in geringem Maße. Die Zugabe von Glucose (bis 4 g/L) erhöhte hingegen dessen Aktivität. Die Kathepsin-d-Aktivität war am höchsten bei Incubationstemperaturen von 33 bis 53 °C; sie wurde beeinflußt durch eine Abnahme der Wasseraktivität und war unbeeinflußt durch Druck.SummaryThe effect of curing agents (nitrate, glucose, ascorbic acid and chloride) and physical parameters (temperature, water activity and pressure) on porcine muscle cathepsin D has been studied. Chloride (in the assayed range 0 to 75 g Cl-/L) showed a strong inhibitory effect. Nitrate (in the assayed range 0 to 800 mg/L) and high concentrations of ascorbic acid (4 to 8 g/L) slightly inhibited cathepsin D. However, its activity increased when glucose was added up to 4 g/L. Cathepsin D activity was maximal when incubated at 33 to 53° C, was affected by a decrease in water activity and unaffected by pressure.

Effect of a new emulsifier containing sodium stearoyl-2-lactylate and carrageenan on the functionality of meat emulsion systems

The emulsion capacity and stability of a new emulsifier containing sodium stearoyl lactylate plus iota carrageenan (SSL/iC) in comparison to caseinate and soy isolate was analysed. The emulsion capacity and stability of SSL/iC in oil/water (O/W) model system emulsions was higher than shown by caseinate and soy isolate. However, the O/W emulsion stability was negatively affected by sodium chloride addition, but positively affected by an increase in temperature. Meat batters were made with caseinate, soy isolate, and SSL/iC at the minimum concentration that showed a good performance (>75% stability) in the O/W emulsions. The emulsifier SSL/iC produced high cook yields and good stability when used in meat batters. However, the cooked meat batters containing SSL/iC showed texture characteristics highly detrimental to the sensory analysis. On the other hand, the addition of 2% potato starch reduced the differences in texture parameters among the samples made with the different emulsifiers.