Dry-cured Ham Research Articles

Impact of gilt immunocastration on weight losses and instrumental and chemical characteristics of Teruel dry-cured ham

A total of 32 fresh hams intended for the Spanish Protected Designation of Origin “Teruel ham” were used to evaluate the impact of gilt immunocastration (vs. entire gilts) on weight losses during the dry-curing process. After processing, 20 dry-cured hams (10 of each group) were chosen at random to assess instrumental and chemical characteristics. Hams from immunocastrated gilts tended (P = 0.057) to present lower weight losses, they were fattier (P < 0.05) at both subcutaneous and intramuscular levels and had lower (P < 0.05) water activity and volatile compounds that provide unpleasant odors than those from entire gilts. However, immunocastration increased (P < 0.05) slightly sodium chloride and sodium nitrite contents, being normal levels. Fatty acid profile was not significantly affected (P > 0.05). It can be concluded that, in general, immunocastration could be a good strategy in gilts to improve the quality of Teruel dry-cured ham.

Bioactive and Sensory Di- and Tripeptides Generated during Dry-Curing of Pork Meat.

Dry-cured pork products, such as dry-cured ham, undergo an extensive proteolysis during manufacturing process which determines the organoleptic properties of the final product. As a result of endogenous pork muscle endo- and exopeptidases, many medium- and short-chain peptides are released from muscle proteins. Many of them have been isolated, identified, and characterized, and some peptides have been reported to exert relevant bioactivity with potential benefit for human health. However, little attention has been given to di- and tripeptides, which are far less known, although they have received increasing attention in recent years due to their high potential relevance in terms of bioactivity and role in taste development. This review gathers the current knowledge about di- and tripeptides, regarding their bioactivity and sensory properties and focusing on their generation during long-term processing such as dry-cured pork meats.

Guidelines to build PLS-DA chemometric classification models using a GC-IMS method: Dry-cured ham as a case of study

The number of representative samples to build a calibration model plays a major role in the success of chemometric models for class discrimination; therefore, knowing which samples should be used for the calibration of prediction models is essential. The aim of this work is to design a basic guideline for the training of partial least squares discriminant analysis (PLS-DA) models to classify complex samples analysed by Gas Chromatography (GC) coupled to Ion Mobility Spectrometry (IMS) using dry-cured Iberian ham as an example. The effect of the number, proportion and class of samples for training and validation and the use of two data types (spectral fingerprint or pre-selected markers) has been assessed by analysing with GC-IMS nearly 1000 dry-cured Iberian ham samples obtained from 7 different curing plants. Subsequently, these were classified with PLS-DA according to the pig's feeding regime (acorn-fed vs. feed-fed) and it has been demonstrated that 450 out of 997 samples are enough for model training to achieve a maximum average prediction accuracy rate. Furthermore, the use of pre-selected GC-IMS markers provides slightly better prediction results than the use of the complete spectral fingerprint. In summary, these results represent a tentative guide for the classification of samples in an industrial setting using GC-IMS and PLS-DA. This methodology would allow authorities and producers to ensure the quality of the agri-food products put on the market as is proven in this study.

Effectiveness of nets treated with food-grade coatings following various drying methods for controlling mite growth on dry-cured hams

Tyrophagus putrescentiae (Schrank), commonly referred to as the ham mite, may infest dry-cured pork during aging. Food-grade propylene glycol (PG) coated ham nets inhibit mite growth and reproduction, but there are application challenges, including shipping costs and handling. Therefore, the objective of this research aimed was to determine if the food-grade coating treated ham nets were still effective at controlling mite growth after drying. Using previously developed methods, polyester nets were coated with a food-grade solution of 40% PG, 1% propylene glycol alginate, and 1% carrageenan. Six treatments were evaluated: no net (NC), coated and wet net (WC), uncoated net (UC), oven-dried for 7 min at 93.3 °C (OD7m), oven-dried for 20 min at 93.3 °C (OD20m), and counter-dried at 22-23 °C for 24 h (CD24h). Ham cubes (2.5cm × 2.5cm × 2.5 cm) were wrapped in the nets (n = 5/trt) and inoculated with 20 adult mites. The cubes were stored in ventilated jars at 25 °C and 70% relative humidity for 14 d. Mites on each ham cube were counted after the 14 d incubation period. A randomized complete block design was used to determine if differences existed (P ≤ 0.05) among treatments. Duncan's multiple range test was used to separate treatment means when differences existed. The OD7m, CD24h, and WC treatments had fewer mites (P ≤ 0.05) than the OD20m and UC treatments; the C treatment had the greatest (P ≤ 0.05) mite count. The OD7m and CD24h treatments lost 37.3% and 36.5% of their starting weights, respectively, while OD20m lost 72.0%. The greater loss (P ≤ 0.05) for the OD20m treatment may have affected the treatment's efficacy. In addition, drying coated nets did not affect the mechanical quality of nets nor the sensory quality of hams when they were wrapped in dried coated nets.

Key Factors Determining the Behavior of Pathogens in Dry-Cured Ham after High Pressure Processing

High pressure processing (HPP) inactivates pathogens and increases the safety of ready-to-eat meat products. The high-pressure lethality and the behavior of the surviving cells after HPP depends on process parameters (pressure and time), microorganism and matrix characteristics. The aim of the present study was to quantify the impact of pressure level, water activity (aw), and fat content on the behavior of Salmonella spp. and Listeria monocytogenes during refrigerated storage of dry-cured ham after high-pressure processing. Salmonella enterica serotype London CTC1003 and L. monocytogenes CTC1034 were inoculated at ca. 7 log cfu/g in dry-cured ham of different aw (0.87–0.98), vacuum packaged, pressurized from 300 to 852 MPa for 5 min, and stored at 7 °C for up to 2 months. Salmonella and L. monocytogenes populations were monitored by plate count during the storage of the hams. The gamma concept was used to quantify the individual effects of aw and storage temperature on the pathogen growth/no-growth behavior in pressurized dry-cured ham. The Weibull (inactivation) or Logistic (growth) primary models were fitted to the log change of pathogen levels during storage of dry-cured ham after pressurization. According to the gamma approach, the refrigeration temperature and aw were the main factors limiting the growth of Salmonella and L. monocytogenes, respectively, in dry-cured ham. Under conditions not allowing growth, the effect of increasing pressures on the microbial inactivation depended on the aw of dry-cured ham and the pathogen; dry-cured ham with high fat content with an aw ≥ 0.95 enhanced the inactivation of Salmonella whereas it reduced that of L. monocytogenes. Under conditions allowing growth of L. monocytogenes, the increase in aw from 0.96 to 0.98 reduced the lag time with no apparent impact on the growth rate.

Drying characteristics of a Japanese dry-cured ham model: Effect of temperature and humidity

The drying characteristics of a Japanese dry-cured ham model containing uniformly distributed brine were investigated. A higher effective moisture diffusivity was obtained at a lower relative humidity (RH) level. The activation energy of effective moisture diffusivity at 40 and 70% RH increased with decreasing moisture content, and was almost constant in the late stage of drying. Therefore, the moisture likely diffused without a large difference in the moisture distribution in the sample. In contrast, under low (10%) RH, the activation energy drastically increased with decreasing moisture content in the initial stage of drying. From the results of magnetic resonance imaging, the moisture content on the surface was drastically decreased; the surface was dried and hardened temporarily (i.e., case hardening) by the fast transfer of moisture. In the middle to late stages of drying, the activation energy gradually decreased to the similar values as at 40 and 70% RH in the late stage of drying. From the results of magnetic resonance imaging analysis after drying, the moisture distribution near the surface no longer exhibited a sharp difference in moisture concentration. The partly dried state of the surface could be alleviated by the transfer of moisture from the inside of the sample. Comparing the energy consumption for drying up to 175% dry basis, the drying condition of 35°C and 40% RH was the most efficient.

Dry-cured ham thickness is a limiting factor for its sanitization by E-beam treatment

Dry-cured ham thickness is a limiting factor for its sanitization by E-beam treatment

Impact of oxidation on the cardioprotective properties of the bioactive dipeptide AW in dry-cured ham

Unbalanced oxidative reactions occurred during the dry-curing period of ham can trigger unpleasant taste. Additionally, salt might mediate in these reactions that cause the oxidation of some of the generated peptides acting as a pro-oxidant. The influence of the processing and oxidation on the release of peptides and bioactivity have been dimly investigated. In this study, the dipeptide AW, and its oxidized form AWox were quantitated in dry-cured ham. AW concentration reached 4.70 mg/g of dry-cured ham at 24 months of traditional dry-curing. The intact and the oxidized peptide forms accumulated to 5.12 and 6.80 µg/g dry-cured ham in 12-months low-salted hams, respectively, while they were undetectable in 12 months-traditionally elaborated hams. Moreover, oxidation affected the antioxidant properties depending on the in vitro assay and reduced the AW potential as antihypertensive. This study reports the potential role of the dry-cured ham-derived peptide AW on cardiovascular health and the relevance of post-oxidation on its bioactivity.

Insight into the relationship between microorganism communities and flavor quality of Chinese dry-cured boneless ham with different quality grades

Microorganisms played a key role in developing the flavor quality, while few studies focused on the relationship between microbial diversity and flavor quality of dry-cured boneless ham. To explore the relationship, sensory evaluation, lipases, microorganism communities, free fatty acids and volatile compounds were investigated in dry-cured boneless ham with different quality grades (NS, WS and GS groups); the correlation between cored microbes and crucial volatiles was further evaluated by metabolic network analysis. GS group showed the highest scores in aroma and overall acceptance among three groups. The highest values of phospholipase activities (7.88 U*g−1 protein) were shown in GS group, while the lowest values of TBARS (0.93 mg/kg) were observed in GS among three groups. High-throughput sequencing revealed that fungi showed the most various among three groups; Xerochrysium, Aspergillus, Penicillium and Debaryomyces were the most genera in GS. SPME-GC-MS revealed that GS showed higher contents and numbers in volatiles than other groups; aldehydes and furans were intensely response to the variations of volatiles among these groups. Metabolic pathway further revealed that several key species derived from Penicillium and Aspergillus accelerated the formation of volatiles by β-lipoxidation and Strecker degradation. These results indicated that molds could be the major contributors in developing and differentiating the flavor quality of Chinese dry-cured boneless ham.

Spatial discounting in food products from high natural value agroecosystems

Aim of study: To test the hypothesis that consumers’ willingness to pay (WTP) for traditional food products expresses their willingness to conserve the bundle of ecosystem services (ES) provided by the territories of origin and that the intensity of these preferences is subject to spatial discounting. Area of study: We used Iberian dry-cured ham as a case study. This is a traditional and highly appreciated product characteristically produced in the Dehesa agroforestry system (southern Iberian Peninsula), an agricultural system characterized by high levels of ES provision. Material and methods: The analysis relies on a discrete choice experiment using some recently developed spatial indexes that go beyond traditional “distance-decay” effects. This method was fed with primary data gathered from a face-to-face survey administered in Andalusian food retail establishments to 1,158 Iberian ham (acorn- or fodder-fed) consumers. Main results: The results provide evidence of the effects of spatial discounting on the purchase of acorn- and fodder-fed Iberian hams associated with the agroecosystem in which they are produced. These effects presumably stem from consumers’ cultural identity linked to the agroecosystem of origin and their willingness to support the local economy and communities. In addition, in the case of acorn-fed Iberian ham, spatial discounting is affected by consumers’ perception of the ES provided by the agroecosystem, with consumers who significantly perceive these services showing a higher WTP, regardless of their place of residence (no spatial discounting). Research highlights: Relevant insights can be gained from the results, especially concerning marketing strategies and the adoption of environmental and sociocultural certifications.

Reply to López-Moreno, M. Comment on "Montoro-García et al. Beneficial Impact of Pork Dry-Cured Ham Consumption on Blood Pressure and Cardiometabolic Markers in Individuals with Cardiovascular Risk. Nutrients 2022, 14, 298".

We thank Dr. López-Moreno for the comment [...].

Ochratoxin A in Dry-Cured Ham: OTA-Producing Fungi, Prevalence, Detection Methods, and Biocontrol Strategies-A Review.

Traditional dry-cured hams are easily contaminated by toxigenic fungi during the fermentation and ripening stages. The detection and positive rates of ochratoxin A (OTA) are the highest among mycotoxins detected in traditional dry-cured hams, indicating that OTA in hams is a potential safety hazard to human health. This review addresses the mycotoxin-producing fungal species, the toxigenic conditions causing OTA contamination worldwide, the prevalence of OTA contamination in dry-cured hams, and the detection methods applied in OTA analysis. Additionally, this study introduces methods to prevent and control OTA in traditional dry-cured hams. The growth of common mycotoxin-producing fungi and the accumulation of mycotoxins in dry-cured ham can be controlled by a microbial starter. This review provides an important theoretical foundation for the research and control of OTA in traditional dry-cured hams.

Correlation of characteristic flavor and microbial community in Jinhua ham during the post-ripening stage

In this work, the changes in volatile flavor compounds and microbial communities in post-ripening Jinhua ham were analyzed. Hexanal and nonanal were the main flavor substances in Jinhua ham stored for 1-3 years, and the content of which were increasing during the post-ripening stage and finally reached 261.80 μg/100g and 445.33 ± 15.29 μg/100g, respectively. High-throughput sequencing showed that Aspergillus, Saccharomyces, Staphylococcus, and Cobetia were the dominant microorganisms in post-ripening Jinhua ham. The dominant fungi were Aspergillus (post-ripened for 1-2 years) and Saccharomyces (post-ripened for 3 years). Staphylococcus accounted for the largest proportion of the bacteria in Jinhua ham, and the proportion gradually increased with the passage of time, from 50.21% to 64.66% during the post-ripening. Spearman correlation analysis showed that Saccharomyces (P < 0.001), Aspergillus (P < 0.01), and Staphylococcus (P < 0.05) were positively correlated with the flavor of Jinhua ham in the post-ripening stage. The revealed correlation of microorganisms and the flavor in post-ripening Jinhua ham can be a foundation for the quality improvement of dry-cured ham and the development of fermented meat starter.

Analysis of flavor formation during the production of Jinhua dry-cured ham using headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS)

This study aimed to clarify the formation process of flavor compounds and identify the volatile substances present during a continuous period of Jinhua dry-cured ham (JDH) making. Via headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS), a total of 53 volatile organic compounds (VOCs), including 20 aldehydes, 16 alcohols, 11 ketones, 5 esters and 1 furan, were identified in JDH from seven sampling stages. The results showed that butanal, 3-methylbutanal, 2-methylbutanal, 2-hexanone, 2-pentanone and 2-butanone could be flavor markers in the evolution of aroma characteristics of JDH. Aldehydes (2-methylbutanal and 3-methylbutanal), alcohols (2-methylpropanol, 2-methylbutanol, 3-methylbutanol and 1-penten-3-ol), ketones (2-pentanone, 2-propanone, 2-butanone and 2-hexanone) and esters (ethyl acetate and ethyl 3-methylbutyrate) were considered the main VOCs in the mature JDH. Free fatty acid (FFA) analysis displayed the changes in intramuscular fat (IMF) of JDH. Additionally, principal component analysis (PCA) showed that drying-ripening was a critical stage in the flavor formation of JDH.

Investigation of ochratoxin A in commercial cheeses and pork meat products by liquid chromatography-tandem mass spectrometry.

Ochratoxin A (OTA) is a mycotoxin produced by several species of Aspergillus and Penicillium and commonly detected in a wide range of foodstuffs. The purpose of this work was to monitor the presence of OTA in cheeses and pork meat products. A simple and accurate "dilute and shoot" method with no need of immunoaffinity column and isotopic labeled internal standard, by liquid chromatography-tandem mass spectrometry, was validated in accordance with the criteria set out in Commission Regulation (EC) No. 401/2006. The method showed good linearity in solvent and in matrix (R2 ≥0.995), limit of detection was 0.2µg/kg for cheese and 0.3µg/kg for pork meat products, limit of quantification was fixed at 1µg/kg, and recovery was estimated at two different concentration levels (1 and 5µg/kg) and ranged from 75% to 101%. The interday and intraday laboratory precisions were lower than 7%. The matrix effect, the recovery of the extraction process, and the overall process efficiency were evaluated. No significant ME was observed in the two matrices considered. This method was applied to the analysis of 75 samples, coming from official controls implemented by the Lazio Region (Central Italy). In one sample of dry-cured ham, the concentration found (69.3µg/kg) was well above the guidance value recommended by the Italian Ministry of Health (1µg/kg). These data together with the detection of OTA in three grated cheeses suggest the importance of monitoring these products. Considering the high dietary intake of these matrices, especially among vulnerable populations, further research should be devoted to estimate exposure and risk assessment for OTA.

Evaluation and selection of yeasts as potential aroma enhancers for the production of dry-cured ham

Yeasts play a critical role in the flavor formation of dry-cured ham. In this study, 41 yeast isolates from the dry-cured ham at different processing stages were evaluated for their technological properties. Debaryomyces hansenii was the most dominant yeast and has been detected at each phase of dry-cured ham, followed by Candida zeylanoides which was mainly detected in salting phase. Yarrowia bubula and Yarrowia alimentaria were found at the first two-phase of dry-cured ham. All isolates of yeast showed enzymatic activities against milk protein and tributyrin, while only 4 strains displayed proteolytic activity on meat protein. Yeast strains were grown in a meat model medium and volatile compounds were identified. The result showed that inoculated yeast strains could promote the production of volatiles and there were significant differences among strains. D. hansenii S25 showed the highest production of volatile compounds, followed by the strain C. zeylanoides C4. D. hansenii S25 was the highest producer of alcohols showing the highest production of benzeneethanol and 3-(methylthio)-1-propanol. Based on OAV and PLS analysis, D. hansenii S25 was strongly correlated with overall flavor and key volatile compounds of dry-cured ham, which could be selected as potential starter cultures.

Effect of Xuanwei Ham Proteins with Different Ripening Periods on Lipid Metabolism, Oxidative Stress, and Gut Microbiota in Mice.

Consumption of dry-cured ham may have a cardiovascular disease preventive capacity. However, whether ham protein in the maintenance of health and prevention of disease is dependent on ripening periods need to be clarified. Fifty C57BL/6 mice consume a diet that contains either Casein, raw ham protein (XWH0), or Xuanwei ham protein after 1-, 2-, or 3-years of maturation (XWH1, XWH2, or XWH3) for 4 weeks. Results show that longer ripening periods in the Xuanwei ham groups are negatively correlated with body weight gain, adipose tissue weight, total cholesterol (TC), and triglycerides levels in serum and liver, and these proteins intake could maintain liver health, reduce lipid deposition and oxidative stress, regulate lipid metabolism-related genes expression, alter the gut microbiota, and promote short-chain fatty acid production. Remarkably, XWH3 intake maintains lower TC and low-density lipoprotein cholesterol levels in serum and has high antioxidative activity as well. This regulation of lipid metabolism and oxidative stress may be related to the AMPK/Nrf2 signaling. Xuanwei ham dietary proteins that have endured a specific ripening period may have preventive effects on metabolic syndrome, which provide a basis for new ideas for nutritional health interventions.

Evaluation of protein degradation and flavor compounds during the processing of Xuan'en ham.

Protein degradation occurs during the processing of dry-cured ham, which has important influences on the flavor and quality of products. The aim of this work was to study the degradation kinetics of myofibrillar proteins (MPs) and sarcoplasmic proteins (SPs) extracted from the biceps femoris muscle during the processing of Xuan'en ham. A relationship between protein degradation and the flavor formation was found. During the processing of Xuan'en ham, MPs and SPs were mainly degraded in the salting stage and incipient fermentation. Accompanied by protein degradation, the content of carbonyl group in SPs increased gradually, but in MPs, it first increased and then decreased. Interconversion between sulfhydryl and disulfide bonds was investigated during this processing. Oxidation, degradation, and thermal effects significantly affected the surface hydrophobicity of proteins. More than one hundred volatile compounds have been identified at each stage of ham preparation. Among them, organic acids were the predominant group, followed by hydrocarbons, aldehydes, alcohols, ketones, and esters.

Evidence of the mechanism underlying zinc protoporphyrin IX formation in nitrite/nitrate-free dry-cured Parma ham

A large amount of zinc protoporphyrin IX (ZnPP) is found in nitrite/nitrate-free dry-cured meat products, such as Parma ham, and is known to contribute to the favorable bright red color of the latter. ZnPP is a metalloporphyrin, in which zinc is coordinated, instead of iron, in the porphyrin ring. ZnPP proved to be more stable than heme, and its formation should be favored in dried meat products to improve color without the addition of nitrites or nitrates. Toward that, understanding the mechanisms of formation of ZnPP in nitrite/nitrate-free dry-cured ham would be important. In this lecture, I introduce some of our research group's findings regarding the endogenous and exogenous factors contributing to the formation and distribution of ZnPP in Parma ham and why ZnPP formation is suppressed in common cured meat products.

Effect of Muscle Fibre Type on the Fatty Acids Profile and Lipid Oxidation of Dry-Cured Venison SM (semimembranosus) Muscle.

The aim of the study was to describe the effect of fibre type on the fatty acid profile and lipid oxidation observed in dry-cured ham produced from individual semimembranosus venison (roe-deer, fallow deer, deer and wild boar) muscles. The results indicated that wild boar meat was characterised by the highest percentage of IA fibres and it contained the higher percentage of MUFA, but a low of PUFA and SFA, and was characterised by a(n-6)/(n-3) ratio lower than in the case of deer meat and greater susceptibility to oxidative changes. The highest percentage of SFA, and the lowest of MUFA and PUFA, was recorded in fallow deer meat, which was also characterised by the highest percentage of white fibres. The curing and drying processes increased the percentage share of SFA and the susceptibility of muscle lipids to oxidation, decreased the percentage of PUFA, and caused insignificant changes in the (n-6)/(n-3) ratio of fatty acids. The products were also characterised by a low amount of fat.