Thermal and photochemical degradation of myoglobin pigments in relation to colour stability of sliced dry-cured Parma ham and sliced dry-cured ham produced with nitrite salt

Lipophilic and hydrophilic extracts of the red pigments from Parma ham and nitrosylated pigment of dry-cured ham produced with nitrite salt were prepared with acetone/water (75/25 v/v %) solution and aqueous phosphate buffer, respectively. The spectral characteristics differed for both the lipophilic and the hydrophilic Parma ham pigment compared with the dry-cured ham produced with nitrite salt. The red lipophilic pigment(s) extractable from Parma ham was(were) found to be very stable towards thermal degradation in acetone/water (75/25 v/v %) solution for temperatures up to 70 °C in contrast to the lipophilic pigment(s) extractable from dry-cured ham produced with nitrite salt, which was(were) found to have an energy of activation of 99 kJ/mol for thermal degradation. In contrast, quantum yields for photodegradation of the lipophilic ham pigments exposed to 366 nm (420 nm) monochromatic light were larger for Parma ham than for nitrite-cured ham [1.6×10^–5 (6.9×10^–6) versus 1.6×10^–6 (2×10^–6) mol einstein^–1] as determined for acetone/water (75/25 v/v %) solution. In agreement with these findings for the extracted lipophilic pigments, sliced Parma ham showed better colour stability than sliced dry-cured ham produced with nitrite salt, when stored in the dark at low oxygen concentration, in contrast to a faster initial discolouration for Parma ham when exposed to light, as shown for chilled storage for 35 days under retail conditions for the two products each packed at two oxygen levels (0.4 and 21%).     

Lipolysis in dry-cured ham maturation

Thirty light Parma hams were tested for muscle lipolytic activity (acid and neutral lipase activity) and free fatty acid (FFA) amounts in M. semimembranosus and biceps femoris, during progressive phases (0, 3, 6, 10 months) of dry-cured ham manufacturing. No correlation was found between the activities of acid and neutral lipases in fresh M. semimembranosus, while during processing the activities were positively related (p<0.1), probably due to effects of muscle composition changes on lipolytic activities. In each processing step tested, acid lipase activities were higher in the M. semimembranosus than in the M. biceps femoris, and FFA amounts varied accordingly, the only exception being for the very dehydrated 10-month old M. semimembranosus, which yielded lower FFA than in the corresponding M. biceps femoris. FFAs in the end product correlated positively with acid and neutral lipase activities of green ham, suggesting that FFA production could be influenced by both raw meat properties and muscle composition during processing.     

干腌火腿研究

新鲜腿肉经切块、干腌、干燥和发酵制成块状干腌火腿。肉块盐分含量小于9%,发酵时腐败变质;肉块盐分含量大于15.5%,发酵后不会腐败变质,但也不会产生火腿香气;肉块盐分含量10%～13%,水分含量42%～48%,发酵后不发生腐败变质并可产生火腿香气。发酵时腐败变质的肉块具有较高的pH和很高的挥发性盐基氮含量;不腐败又不产生香气的肉块具有较低的pH和很低的挥发性盐基氮含量;不腐败并产生火腿香气的肉块具有适中的pH和适中的挥发性盐基氮含量。     

低盐干腌火腿的加工

干腌火腿风味独特，深受消费者青睐，但传统干腌火腿含盐量高，对其消费量和食用者健康均有不利影响。从火腿的成熟机理出发，综述了低盐干腌火腿的研究近况，指出低盐干腌火腿加工应注意的问题。     

Penicillium populations in dry-cured ham manufacturing plants

Seven ham manufacturing plants were sampled for 1 year to assess the mycoflora present in the air and on hams, with special attention given to potential mycotoxin producers. Temperature and relative humidity were recorded in the ripening rooms. Maturing rooms held hams from 2 to 3 through 6 to 7 ripening months, and aging rooms held hams for the following 6 to 7 months, until the 14-month ripening point, when they were ready for the market. Mean temperatures and relative humidities registered during the study were 14.9 degrees C and 62.4%, respectively, in maturing rooms and 16.3 degrees C and 57.6% in aging rooms. Aspergilli and penicillia, potential mycotoxin producers, were isolated in all the plants from the air and the ham. Aspergilli represented 5% of the isolates, while penicillia were largely dominant, with Penicillium nalgiovense being the most represented species (around 60% of the penicillia), followed by Penicillium nordicum, with 10 and 26% of the penicillia isolated, respectively, from the air or the ham. Ochratoxin A production ability, checked in vitro at 250C, was observed in 50% of the P. nordicum isolates obtained both from the air and the ham. Air and ham surface contamination by penicillia was greater in the ripening rooms, where higher temperatures were registered. A certain correlation was also observed between air and ham surface contamination. On the basis of this study, P. nordicum, the ochratoxin A producer that is notable on proteinaceous substrates, is normally present in ham manufacturing plants in Italy, even though not a dominant species. Further studies are necessary to clarify and ensure if dry-curing conditions minimize the potential risk of ochratoxin A formation in the product.     

Factors affecting dry-cured ham consumer acceptability

The objectives of the present study were (1) to compare the relative importance of price, processing time, texture and intramuscular fat in purchase intention of dry-cured ham through conjoint analysis, (2) to evaluate the effect of dry-cured ham appearance on consumer expectations, and (3) to describe the consumer sensory preferences of dry-cured ham using external preference mapping. Texture and processing time influenced the consumer preferences in conjoint analysis. Red colour intensity, colour uniformity, external fat and white film presence/absence influenced consumer expectations. The consumer disliked hams with bitter and metallic flavour and with excessive saltiness and piquantness. Differences between expected and experienced acceptability were found, which indicates that the visual preference of consumers does not allow them to select a dry-cured ham that satisfies their sensory preferences of flavour and texture.     

Salt distribution in dry-cured ham measured by computed tomography and image analysis

Forty-seven hams were scanned four times by computed tomography (CT) while being manufactured into dry-cured hams. An image-processing algorithm measured CT values in the lean part of the hams and provided line profiles reflecting the magnitude and spatial location of salt gradients. At the end of manufacturing, seven entire hams were dissected and the salt content of the lean part determined. Likewise, in the remaining 40 hams, the lean meat of the slices corresponding to the CT images was dissected, analyzed chemically for NaCl and compared to the CT value. The salt content of entire dry-cured hams correlated well (r(2)=0.94) to the CT value of a 10 mm section located at the center of femur bone, perpendicular to the length axis of the hams. In the same position, significant correlations between the CT values before (r(2)=0.71) and after (r(2)=0.80) the ageing period and actual chemical analysis of the same section were demonstrated. Line profiles illustrating the combined salt distribution and dehydration within a ham related to the physical characteristics of the ham as well as to the manufacturing process. These findings reveal that the effects of altered manufacturing practices can be followed non-invasively, while hams are still in production. Computed tomography combined with appropriate image analysis offers advantages as a non-invasive tool in both research and product development.     

Lipid and cholesterol oxidation products in dry-cured ham

An investigation was carried out on oxidative processes in dry-cured hams. Sixteen hams of various ageing times were divided into lean and fat parts, simulating typical consumer habits. All samples underwent analysis of peroxide value (PV), rancidity index (TBARs), 5 cholesterol oxidation products (COPs) and, in the lean samples, proximate composition. While the lean part was rather unaffected by oxidation, the external fat contained some of COPs, TBARs and PV. Comparison of hams at different ageing times revealed that lipid oxidation was substantially unaffected by the time of processing. It is concluded that good manufacturing practice will generally prevent oxidative damage in the edible part of dried hams, even if very long ageing times are used.     

Microstructural changes in Teruel dry-cured ham during processing

Dry-cured ham, "Protected Designation of Origin (PDO)" Teruel, is a high quality meat product processed using a traditional dry-curing procedure. The objective of this paper was to study the microstructure of the Biceps femoris and Semimembranosus muscles during "PDO Teruel" dry-cured ham processing using electron microscopy techniques (Cryo-SEM, SEM and TEM). The Semimembranosus and Biceps femoris muscles from raw ham show the typical structure of muscle tissue in meat. The muscle fibres appear firmly attached to one another by the endomysial connective tissue; the myofibrils inside the cells are strongly attached to each other and to the sarcolemma. In raw ham, the typical structural elements that constitute the sarcomere can be observed by TEM. Important microstructural changes are observed following salting; reflected in the fact that the Z-disks inside the myofibrils are no longer in line and there is important degradation of the cell membranes in this stage. At the end of the process, an accumulation of solutes, which could be products from proteolysis occurring mainly in the last stage of ripening, could be observed in both muscles. Thus the proteolysis and dehydratation phenomena that take place during "PDO Teruel" dry-cured ham processing occur at an ultrastructural level, and this is the basis to produce a product with the sensory features appreciated by consumers.     

五种云南火腿游离脂肪酸含量比较分析

采用气相色谱-质谱联用仪(GC-MS)对宣威火腿、诺邓火腿、鹤庆圆腿、撒坝火腿及三川火腿共5种云南干腌火腿肌内及皮下部位进行游离脂肪酸种类及含量比较分析。结果表明,5种火腿中的游离脂肪酸种类最多检测出16种,棕榈酸(C16∶0)、硬脂酸(C18∶0)、油酸(C18∶1 n-3)、和亚油酸(C18∶2)是5种云南火腿的主要脂肪酸,且不同火腿及不同部位间的脂肪酸组成及含量存在差异(P 0. 05);以诺邓火腿和三川火腿的含量最高,诺邓火腿肌内及皮下脂肪部分的游离脂肪酸总量分别为40. 378 mg/g、79. 959 mg/g,三川火腿的为42. 336 mg/g与77. 548 mg/g,其次分别为撒坝火腿(30. 147 mg/g、62. 049 mg/g),宣威火腿(28. 446 mg/g、62. 078 mg/g)与鹤庆圆腿(27. 361 mg/g、55. 953 mg/g);肌内及皮下的不饱和脂肪酸总含量与必需脂肪酸含量,诺邓火腿与三川火腿均高于其余火腿,因此诺邓火腿与三川火腿的脂肪组成较其他3种火腿更为合理。     

High pressure treatment of dry-cured Iberian ham. Effect on radical formation,lipid oxidation and colour

The effect of high-pressure treatment (200, 400, 600 and 800 MPa) on radical formation in solid samples of dry-cured Iberian ham and in ham slurries was evaluated using the spin-trapping technique and electron spin resonance (ESR) spectroscopy. In addition, hexanal was, as a secondary lipid oxidation product, assessed by gas chromatography. The effect of pressure treatments on ESR signals determined in the spin-trapping assay following pressure treatment in solid samples of dry-cured Iberian ham was not statistically significant. However, the lowest level of pressure applied initiated radical formation and promoted lipid peroxidation, whereas intermediate to high levels of pressure seemed to promote further reaction and disappearance of free radicals. Pressure significantly affected hexanal content in the same way as seen for formation of free radicals. Regarding the slurries prepared from dry-cured ham, pressure significantly increased the tendency of radical formation as seen from the ESR signals and significantly increased the hexanal content. The different pattern between solid ham and ham slurries points toward an initiation mechanism associated with the membrane phospholipids for oxidation. In addition, surface colour (L*, a* and b* values and percent reflectance values) of non-pressurized and pressurized (200–800 MPa) dry-cured Iberian ham samples was assessed. Non-pressurized samples showed a higher lightness than pressurized samples, and redness significantly decreased with pressure treatment.     

干腌火腿中霉菌毒素研究的进展

从干腌火腿中分离到一些霉菌菌株在培养基中生长时可以产生黄曲霉毒素、环匹阿尼酸、青霉酸、梗曲霉素、展青霉素、灰黄霉素、霉酚酸、赭曲霉毒素、橘青霉素和疣孢苷啶等多种霉菌毒素。生成霉菌毒素的霉菌都属于青酶和曲霉。鲜绿青霉可以在干腌火腿中生成环匹阿尼酸,且这种霉菌毒素在干腌火腿中具有较高的稳定性,从而对干腌火腿的安全性构成很大的威胁。将无毒性的霉菌菌株进行培养并接种到干腌火腿上,可防止干腌火腿中形成霉菌毒素。     

Changes in proteins during Teruel dry-cured ham processing

The aim of this work was to investigate the degradation of the water-soluble and myofibrillar proteins during the production of "PDO Teruel" cured ham using SDS-PAGE, and measurement of proteolytic activities (cathepsins B+L, cathepsin L, cathepsin D), as factors that influence the sensory characteristics of this product. This paper contributes to the specific characterisation of a product included in the European Union list of special quality products. The results showed that water-soluble proteins decrease considerably due to salting out and drainage after salting. The degradation of myofibrillar proteins is more pronounced during the ripening process, particularly in the last four months when the main proteins responsible for the structure of muscular tissue are affected. There is an important residual enzymatic activity for cathepsin B, L and D, which must be a decisive factor in the proteolysis observed during "PDO Teruel" ham processing.     

Proteomic analysis of semimembranosus and biceps femoris muscles from Bayonne dry-cured ham

The aim of the study was to delineate and compare the proteomic maps of two muscles of dry-cured ham: the biceps femoris and the semimembranosus. For this purpose, we used two-dimensional electrophoresis on a subcellular muscle fraction: insoluble protein in low ionic strength buffer. After protein identification by MALDI-TOF mass spectrometry and bioinformatic analyses, we found differences in expression levels in the two muscles. Seventy-three proteins or fragments were differentially expressed: 43 were over-represented in semimembranosus and 30 in biceps femoris. Although the study was performed on the insoluble protein fraction in low strength ionic buffer, protein and fragment identifications by mass spectrometry showed that most of the proteins were involved in energy metabolism. The differences observed between the two muscles can be explained by the differences in salt and moisture content in the course of dry-cured ham processing.     

Characterisation of microbial deep spoilage in Iberian dry-cured ham

The purpose of this work was to investigate the micro-organisms involved in overlooked “bone taint” spoilage of dry-cured Iberian hams. The physico-chemical characteristics of spoiled hams with 12 and 24 months of ripening, showing initial signs of alteration, were analyzed and their correlations with microbial counts studied. The spoilage potential of different microbial groups was assessed by the relationship between the microbial counts and the proteolysis level of spoilage as observed in the degradation of myofribrillar and sarcoplasmic protein fractions and in the changes in free amino acids. Non-enteric gram-negative bacteria (NEGN) were the dominant microbial group, showing a positive correlation with the moisture of spoiled hams. The Catalase-positive cocci (GPCP) growth was favoured by high NaCl concentrations in the spoiled hams, whereas the counts of Enterobacteriaceae were negatively affected by high NaCl concentration. The highest proteolytic microorganisms were the Gram-negative microbial groups playing Enterobacteriaceae a major role in the undesirable changes of the texture properties of the spoiled hams. With respect to the sensorial analysis, a synergy between NEGN and GPCP was observed in most of the strongly spoiled samples.     

Time-related changes in intramuscular lipids of French dry-cured ham

The aim of this study was to investigate the changes in intramuscular lipids during the processing of French dry-cured hams. In the fresh biceps femoris muscle, the lipid content was on average, 105 mg/g DM with a large individual variation. Glycerides accounted for about 75% of total lipids. During processing for 273 days, phospholipid content decreased markedly whereas free fatty acid content rose from 1·9 mg/g DM to 9·4 mg/g DM. Little change affected the fatty acid composition of both glycerides and phospholipids during processing. After a decrease in the proportion of polyunsaturated fatty acids during the first 2 months, free fatty acid composition remained stable. The results suggest that lipid alteration during dry-curing of hams is due to lipolysis and that lipid oxidation is limited.     

Consumer satisfaction with dry-cured ham in five European countries

The objective is to investigate consumer satisfaction with dry-cured ham in five European countries. A logistic regression model has been fitted using data collected through a cross-sectional web-based survey carried out in Belgium, Germany, Denmark, Poland and Greece during January 2008 (n=2437 of which 2156 were dry-cured ham consumers). Satisfaction was evaluated as overall satisfaction, as well as specific satisfaction with healthfulness, price, convenience and taste. The findings show that the main determinant of overall satisfaction is taste satisfaction, hence, producers are recommended to focus on matching sensory acceptability of dry-cured ham. No significant between-country differences were found, reflecting the wide availability of this product in all countries. Consumer characteristics influenced their level of satisfaction. Men, older (age > 52 years) and frequent consumers of dry-cured ham consumption were more likely to be satisfied with dry-cured ham. Consumers trust the butcher's advice and they preferred purchasing dry-cured ham at a butcher shop rather than in a supermarket.     

干腌火腿抗氧化肽的研究进展

自由基过量累积会导致人体许多慢性疾病的产生,如衰老、慢性炎症、心血管疾病等,目前常规的解决方法是使用抗氧化剂。然而人工合成的抗氧化剂对人体有潜在危害,因此无毒副作用的抗氧化肽成为了当今研究的热点。作为发酵肉制品之一的干腌火腿,因其蛋白质含量丰富,且在发酵过程中受到内源酶和微生物的影响,会对蛋白质进行分解,从而产生具有抗氧化活性的小肽。大量的研究表明,来源于干腌火腿的肽具有极强的抗氧化活性。因此,干腌火腿作为天然抗氧化肽的潜在来源,备受研究人员的关注。本文综述了干腌火腿中抗氧化肽研究的最新进展,主要包括抗氧化肽的形成、制备、纯化鉴定及抗氧化机制4个方面,其中特别指出外源微生物对抗氧化肽形成的影响,以期为干腌火腿抗氧化肽的进一步研究提供理论基础。     

Mycoflora and toxigenic Aspergillus flavus in Spanish dry-cured ham

Sixty-five dry-salted hams were analysed. Aspergillus and Penicillium were the dominant genera. In general, the mould flora was dominated by Aspergillus spp. and primarily A. glaucus, A. fumigatus, A. niger and A. flavus. A flavus was found in 16 hams and 9 out of 16 strains examined produced aflatoxins 'in vitro'. Surface samples of dry-salted hams showed growth of inoculated A. parasiticus NRRL-2999 strains and production of aflatoxins in low levels at 25 and 30 degrees C. It is concluded that the presence of toxigenic strains in Spanish dry-salted ham does not constitute a health risk.