Inactivation of Serratia liquefaciens on dry-cured ham by high pressure processing

To quantify the inactivation of Serratia liquefaciens exerted by high pressure processing (HPP), slices of dry-cured ham were inoculated and processed combining different levels of technological parameters: pressure (347–852 MPa), time (2.3–15.8 min) and temperature (7.6–24.4 °C) according to a central composite design. Bacterial inactivation, as logarithmic reduction, indicated that S. liquefaciens was relatively sensitive to HPP. Six log reductions were achieved in a total of 10 trials combining pressures of 600 MPa or above with different holding times and temperatures. The inactivation of S. liquefaciens was analysed through the multiple regression analysis to generate a second order polynomial equation. Pressure and time were the two factors which significantly determined the inactivation of S. liquefaciens on dry-cured ham. Temperature did not significantly affect the lethality of the process. The response surface methodology was used to determine optimum process conditions to maximize the inactivation of S. liquefaciens in the experimental range tested. The maximum inactivation of S. liquefaciens in dry-cured ham was achieved by combining a pressure of 650 MPa with a holding time of 8 min. Combinations above these values (i.e. 750 MPa for 13 min) would not significantly improve the lethality of the process.     

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.     

Dynamics and characterization of yeasts during ripening of typical Italian dry-cured ham

The evolution of the yeast population during manufacturing and ripening of dry-cured Parma ham was investigated. Contamination levels ranged from 10(5) to 10(7) cfu/g on muscle surface, 10(4) to 10(6) cfu/g on covering fat and exceeded 10(7) cfu/g on spreadable fat mince ("sugna"). Two hundred and sixty one yeast isolates underwent identification test, showing that the predominant species of yeast population during the whole maturing process were Debaryomyces hansenii, Candida zeylanoides, Debaryomyces maramus, and to a lesser extent, Candida famata and Hyphopichia burtonii. The species Candida catenulata, Candida guilliermondii, Candida edax and other genera like Cryptococcus and Wingea were occasionally found. The yeast counts and species distribution changed according to the stage of processing and to the ham sampling location. At the end of the cold phase, the washing procedure was effective in lowering the yeast count in muscle and fat surface layers, but during the next ageing stages, yeast colonization of unskinned ham muscle increased again, though species distribution changed if compared to previous manufacturing phases. The ripening steps taken into account from the end of the cold phase to the final outcome, were always characterized by more than one yeast species, suggesting that yeasts other than Debaryomyces spp. could play a remarkable role on the sensory and safety properties of typical Italian dry-cured ham.     

PRKAG3 and CAST genetic polymorphisms and quality traits of dry-cured hams - I. Associations in Spanish dry-cured ham Jamón Serrano

The functional single polymorphisms identified in the calpastatin (CAST) gene have been related to the rate of meat tenderization and the protein turnover after slaughter, and the Ile199Val polymorphism identified in the coding region of the protein kinase AMP-activated (PRKAG3) gene has been proven to affect ultimate pH in muscle. The aim of the present study was to show the effects of these genetic polymorphisms on the quality traits of Spanish dry-cured ham Jamón Serrano. A tissue sample from 665 crossbreed pigs were genotyped for PRKAG3 Ile199Val, CAST Arg249Lys and CAST Ser638Arg polymorphisms, and a subsample of 120 dry cured hams was selected to perform physico-chemical, rheological, instrumental colour and sensory analyses. Associations between the polymorphisms and several quality traits of dry-cured ham, mainly related to flavour and texture, were found. The genotypes PRKAG3 Ile/Ile, CAST249 Arg/Arg and CAST638 Arg/Arg, and the haplotype CAST 249Arg-638Arg were the most favourable for Jamón Serrano production.     

生姜蛋白酶和猕猴桃蛋白酶对干腌羊火腿蛋白质降解的影响

为了促进干腌羊火腿肌肉蛋白质降解,加快其风干成熟进程,缩短加工周期,提高羊火腿的品质,在干腌羊火腿中添加生姜蛋白酶和猕猴桃蛋白酶。以带骨鲜羊后腿肉为试验材料,分别设计一个对照组和两个试验组;对照组不采取处理,而试验组分别添加0.05%的生姜蛋白酶和猕猴桃蛋白酶,并在相应条件下进行风干成熟,检测干腌羊火腿的总氮(Total nitrogen,TN)含量、非蛋白氮(Non-protein nitrogen,NPN)含量和蛋白质降解指数(Proteolysis index,PI)等蛋白质降解指标,并通过SDS-PAGE(聚丙烯酰氨凝胶电泳)分析了干腌羊火腿肌肉蛋白质的降解情况。结果表明,与对照组相比,猕猴桃蛋白酶处理组和生姜蛋白酶处理组的TN含量风干成熟后分别增加了1.2倍和1.3倍、NPN含量分别增加1.5倍和1.7倍、PI分别上升1.2倍和1.3倍;SDS-PAGE分析结果表明,生姜蛋白酶降解肌肉蛋白的效率较猕猴桃蛋白酶强。通过蛋白质将指数和SDS-PAGE电泳结果可知,生姜蛋白酶对肌肉蛋白的降解程度比猕猴桃蛋白酶大。     

A comprehensive review on molecular mechanism of defective dry-cured ham with excessive pastiness,adhesiveness, and bitterness by proteomics insights

Excessive bitterness, pastiness, and adhesiveness are the main organoleptic and textural defects of dry-cured ham, which often cause a lot of financial losses to manufacturers and seriously damage the quality of the product. These sensory and textural defects are related to the protein degradation of dry-cured ham. Proteomics shows great potential to improve our understanding of the molecular mechanism of sensory and textural defects and identify biomarkers for monitoring their quality traits. This review presents some of the major achievements and considerations in organoleptic and textural defects of dry-cured ham by proteomics analysis in the recent decades and gives an overview about how to correct sensory and textural defects of dry-cured ham. Proteomics reveals that muscle proteins derived from myofibril and cytoskeleton and involved in metabolic enzymes and oxygen transport have been identified as potential biomarkers in defective dry-cured ham. Relatively high residual activities of cathepsin B and L are responsible for the excessive degradation of these protein biomarkers in defective dry-cured ham. Ultrasound-assisted mild thermal or high-pressure treatment shows a good correction for the organoleptic and textural defects of dry-cured ham by changing microstructure and conformation of muscle proteins by accelerating degradation of proteins and polypeptides into free amino acids.     

High pressure treatments on the inactivation of Salmonella Enteritidis and the physicochemical, rheological and color characteristics of sliced vacuum-packaged dry-cured ham

The effect of high pressure (HP) on Salmonella Enteritidis in sliced dry-cured ham stored under temperature abuse (8°C) during 60d was investigated. After treatment, reductions of S. Enteritidis were 1.06, 2.54 and 4.32 log units in ham treated at 400, 500 and 600MPa for 5min at 12°C, compared to non-pressurized samples. After 60d, counts of S. Enteritidis in ham treated at 400 and 500MPa were 2.56 and 2.66 log units lower than in non-treated ham, whereas the pathogen was only detected after enrichment in ham treated at 600MPa. Lipid oxidation increased with storage and pressurization, whereas total free amino acid contents were similar in HP and control samples after 60d. Dry-cured ham treated at the highest pressures exhibited lower shear resistance, whereas the maximum force to compress the sample was slightly changed. Color (L*, a* and b*) varied with pressurization and storage. Changes induced by HP in dry-cured ham were attenuated during storage.     

Non-destructive analysis of aw, salt and water in dry-cured hams during drying process by means of computed tomography

Computed tomography (CT) has been previously used as a non-destructive technology to accurately determine salt and water content in dry-cured ham at the initial stages of the elaboration process. However, since the accuracy of predictive models has been affected by the dry level of the sample, in this study, prediction models for salt and water contents and also for a_w to be applied during drying process were developed. Results showed that the number of independent variables needed to obtain regression models with a similar accuracy to the models previously developed is higher in drier samples. Furthermore, an important effect of fat content is also observed since prediction of a_w, salt content and water content were significantly improved when the fattiest samples were removed from the calibration or when fat content was included in the predictive models. Because of the different physicochemical characteristics of muscles, models developed specifically for Semimembranosus (SM), Biceps femoris (BF) or Semitendinosus (ST) muscles were more accurate. It can be concluded that models for prediction during the drying process were accurate enough to consider CT as a useful tool applicable for controlling and optimizing the dry-cured ham elaboration processes.     

Identification of 2-dodecylcyclobutanone and linear-alkanes as irradiation markers in sliced dry-cured ham

The usefulness of 2-dodecylcyclobutanone (2-DCB) and alkane hydrocarbons as irradiation markers in sliced dry-cured ham was evaluated by solid phase microextraction (SPME)-gas chromatography-mass spectrometry (GC–MS). To that aim, sliced dry-cured ham was irradiated with different irradiation doses and subsequently examined together with non-irradiated dry-cured ham used as a control sample. The SPME conditions utilized were selected as a consequence of performing an optimization process. The results found in this work reflected that the presence of 2-DCB may be used as an irradiation indicator in sliced dry-cured ham since it does not occur in non-irradiated samples. This confirms data reported in the literature on irradiated foods, other than ham. Likewise, the concentrations of alkanes C₁₄–C₁₇ increased considerably in samples irradiated with low doses, although a decrease was observed when high irradiation doses were used. As a consequence, the concentration of these compounds can also be used as an irradiation indicator when doses lower than 1.0 kGy are applied. These results are discussed.     

PRKAG3 and CAST genetic polymorphisms and quality traits of dry-cured hams-II. Associations in French dry-cured ham Jambon de Bayonne and their dependence on salt reduction

This study aimed to evaluate the effects of PRKAG3 Ile199Val and CAST Arg249Lys and CAST Ser638Arg polymorphisms on the quality traits of the French dry-cured ham Jambon de Bayonne and their interaction with salt reduction. Significant (p<0.05) and suggestive associations (p<0.10) between the polymorphisms and several quality traits of dry-cured ham, mainly related to processing and textural properties, were found. PRKAG3 Ile/Val and CAST 249Lys/638Arg presented the highest scores for sensory and processing properties, whatever the salt content.     

The Role of Muscle Proteases and Lipases in Flavor Development During the Processing of Dry-Cured Ham

The processing of dry-cured ham is very complex and involves numerous biochemical reactions that are reviewed in this article. Muscle proteins undergo an intense proteolysis, resulting in a great number of small peptides and high amounts of free amino acids. The enzymes responsible of these changes are proteinases (cathepsins B, D, H, and L and, to a less extent, calpains) and exopeptidases (peptidases and aminopeptidases). Muscle and adipose tissue lipids are also subject to intense lipolysis, generating free fatty acids by the action of lipases that, in a second stage, are transformed to volatiles as a result of oxidation. Sensory profiles of dry-cured ham are strongly affected by these enzymatic reactions. In addition, the activity levels of the muscle enzymes significantly depend on the properties of raw ham, such as age and crossbreeding as well as the process conditions such as temperature, time, water activity, redox potential, and salt content. Thus, the control of the muscle enzyme systems, mainly proteases and lipases, is essential for the standardization of the processing and/or enhancement of flavor quality of dry-cured ham.     

Proteomic profile of dry-cured ham relative to PRKAG3 or CAST genotype, level of salt and pastiness

Two-dimensional electrophoresis was used to compare dry-cured biceps femoris insoluble protein fraction according to genotype (PRKAG3Ile199Val and CASTLys249Arg/Ser638Arg) as well as salt and pastiness level. The PRKAG3 affected mainly muscle metabolic enzymes, indicating its possible influence on muscle metabolism with heterozygotes Ile/Val appearing different from both homozygous genotypes. The effect of CAST was smaller, affecting the quantity of one actin fragment. Dry-cured ham salt and pastiness level affected a wide variety of protein spots including metabolic enzymes, plasma proteins, chaperones and myofibrillar proteins, including protein fragments, indicating the connection with proteolysis. Pastiness was associated with salt content, reflected also by the fact that many spots were affected by both factors. Despite the absence of extreme pastiness (or low salt samples), some protein spots (actin, MHC fragment, desmin fragment) exhibited important differences in intensity according to pastiness (and salt level) suggesting they could be used as potential quality markers.     

Effect of low-temperature preservation on the quality of vacuum-packaged dry-cured ham: Refrigerated boneless ham and frozen ham cuts

The effect of storage on dry-cured ham quality was studied. Sixteen vacuum-packaged boneless dry-cured hams and sixteen vacuum-packaged dry-cured ham cuts were stored in darkness under refrigeration (4±2°C; 8 months) or freezing (-18±1°C; 24 months), respectively. Instrumental colour and texture, physico-chemical and biochemical parameters, sensory profile and consumer acceptability and purchase satisfaction were measured throughout storage. The overall quality of refrigerated boneless dry-cured hams and frozen dry-cured ham cuts showed only limited changes throughout long-term storage. Significant changes involved loss of odour and flavour, increased adhesiveness and modification of hardness, the Semimembranosus muscle became tender while Biceps femoris became harder, leading to a higher textural homogeneity. In agreement with those changes, the overall acceptability assessed by a trained panel decreased throughout storage, though this was significant regarding only frozen hams. However, consumer evaluation of acceptability, as well as satisfaction with hypothetical purchasing, did not vary significantly throughout storage.     

云南干腌火腿加工工艺及其品质影响因素研究进展

云南干腌火腿是一种重要的传统发酵肉制品,以猪后腿为原料,经腌制、风干、发酵等加工而成。云南干腌火腿主要有宣威火腿、撒坝火腿、三川火腿、老窝火腿、诺邓火腿及鹤庆火腿等,本文对云南干腌火腿加工工艺及干腌火腿品质影响因素进行综述,从原料肉、腌制条件、色泽及风味等几方面做了详细讨论,旨在为干腌火腿品质改进提供一定的理论参考。     

Texture changes in dry-cured ham pieces by mild thermal treatments at the end of the drying process

The present study evaluated the effects of mild thermal treatments at the end of the drying process on physicochemical characteristics and instrumental and sensory texture in dry-cured ham. Experiment 1: effect of thermal treatments (4–46 °C) for 4 h and 24 h. Experiment 2: time effect (4–168 h) of thermal treatments at 30 °C and 36 °C. Both experiments were done on small dry-cured ham dices. Experiment 3: time effect (4–168 h) of thermal treatment at 30 °C on both instrumental and sensory texture of 4-cm-thick sections of dry-cured ham. The thermal treatment at 30 °C for 168 h on both dry-cured ham muscle dices (20 mm × 20 mm × 15 mm) and dry-cured ham sections (4 cm thick) decreased softness, adhesiveness and pastiness in BF muscle, without increasing hardness in SM muscle or affecting moisture, a_w and proteolysis index.     

无硝干腌火腿中红色素形成机制研究进展

干腌火腿经过长时间腌制发酵成熟,富含生物活性物质,具有良好的感官特性。在传统干腌火腿加工过程中常添加硝盐（硝酸盐或亚硝酸盐）以获得稳定的色泽,然而,由亚硝酸盐与仲胺反应生成的亚硝胺具有致癌风险,已引起人们的广泛关注。研究发现,国外的著名干腌火腿如帕尔玛火腿,在腌制过程中不添加硝盐,其红色的主要贡献者被证实为Zn-原卟啉IX。本文综述了添加硝盐与未添加硝盐干腌火腿中红色素的研究进展,重点探讨Zn-原卟啉IX在无硝干腌火腿加工过程中的形成机制,以期为干腌火腿加工过程的色泽调控提供科学理论依据。     

中西方干腌火腿风味成分比较及形成机理分析

风味对干腌火腿的质量十分重要 ,它与生产所用原料、生产工艺和参数密切相关。文中比较了金华火腿与欧洲几种著名火腿的风味成分 ,结果显示 ,中西方火腿的风味组成相似 ,醇、醛、酮、酯、含硫化合物、含氮化合物、烷、烯烃类物质是干腌火腿的共有成分 ,但各成分的含量在中西方火腿中存在明显差异 ,金华火腿中烷、烯烃含量最高 ,欧洲的几种火腿中醛类物质含量最高。文中同时分析了干腌火腿中各风味成分的特征和可能的形成机理。     

Non-destructive estimation of moisture,water activity and NaCl at ham surface during resting and drying using NIR spectroscopy

This paper describes the ability of near infra-red reflectance (NIR) spectroscopy to predict moisture, water activity (a_w) and NaCl content at the surface of dry-cured ham during the process. A Fourier Transform (FT) NIR spectrometer and two probes (on-contact and remote) were tested directly on the surface (gracilis muscle) of 98 hams during the process. The highest precision was achieved when two spectra per sample were used in the predictive model development. The models based on the remote measurement probe yielded acceptable results with determination coefficients (r²) of 0.93, 0.62 and 0.91 and residual predictive deviation (RPD) of 3.74, 1.63 and 3.33 for moisture, a_w and NaCl content, respectively. These results show that NIR measurements could be included in the control system of the resting and drying processes to prevent crusting in dry-cured ham.     

Micronutrients in Italian ham: A survey of traditional products

The study provides original analytical data on the micronutrient profile of some traditional Italian hams, representative of the major ham categories produced in Italy: 4 dry-cured hams (Modena, Nazionale, Parma, San Daniele), 3 cooked hams (Cotto, Scelto, Alta Qualità), 1 smoked ham (Speck). Data on macronutrients (protein, lipid, moisture), energy, trace elements (Fe, Zn, Cu, Mn, Se), B vitamins (B1, B2, PP, B6, B12) and vitamin E level in the 80 Italian hams sampled are reported. Smoked and dry-cured ham were the richest sources of Fe, Zn and Se and, among vitamins, dry-cured ham had the highest level of B2, PP, B6 and B12; cooked ham provided the lowest energy intake. The contribution of ham to micronutrients recommended dietary allowances was estimated: a ham portion (50 g) was a good source especially of Zn and Se providing over 12% of RDA of both; among B vitamins, dry-cured ham greatly contributed to B1 and B6 vitamins RDA (both over 30%).