Analysis of raw meat to predict proteolysis in Parma ham

Impact of innovative rearing strategies for the Italian heavy pigs: Technological traits and chemical composition of dry-cured hams

To explore the influence of 4 feeding strategies on dry-cured ham quality, 336 barrows and gilts (3 batches, 112 pigs/batch) of 90 kg body weight (BW), were divided into 4 groups and housed in 8 pens with automated feeders. In the control group (C), the pigs were fed restrictively medium-protein feeds and slaughtered at 170 kg BW (SW) and 265 d of slaughter age (SA). With the older age (OA) treatment, the pigs were restrictively fed low protein feeds and slaughtered at 170 kg SW and 278 d SA. The other two groups were fed ad libitum high protein feeds, the younger age (YA) group was slaughtered at 170 kg SW and 237 d SA, the greater weight (GW) at 265 d of SA and 194 kg SW. The hams were dry-cured and seasoned for 607 d, weighed before and after seasoning and deboning. Sixty hams were sampled and sliced. The lean and the fat tissues were separated and analyzed for proximate composition and fatty acid profile. The model of analysis considered sex and treatment as fixed factors. With respect to C: i) OA lowered the ham weight, the lean protein content, increased marbling and decreased the PUFA proportion in intramuscular and subcutaneous fat; ii) YA hams had thicker fat cover with lower PUFA in intramuscular and subcutaneous fat; iii) GW increased the deboned ham weight, fat cover depth and marbling, reduced PUFA in intramuscular and subcutaneous fat, without alteration of the lean moisture content. Sex had a negligible impact.

Application of a non-invasive tool and identification of genetic markers in swine to enhance ham quality: a preliminary study

A genome-wide association study (GWAS) was performed as a preliminary step to identify regions potentially related to ham quality traits. In this research, genomic information was obtained from 238 commercial hybrid pigs utilising the GeneSeek® Genomic Profiler genome-wide porcine genotyping array. Carcasses were tested for hot weight, the thickness of backfat and loin, and lean meat percentage. The corresponding fresh hams were assayed for weight and ultimate pH; the activities of Cathepsin B and Ferrochelatase of Semimembranosus muscle were determined through fluorimetric methods. The lean meat percentage of fresh ham (LMPH), salt absorbed after first (SALT1) and overall salting stages (SALT) were estimated online by the Ham Inspector™ apparatus. Hams were processed in compliance with the procedures established for Protected Designation of Origin Parma ham, and ham weight losses were measured at the main processing stages. Hot carcass weights showed a significant negative correlation with their lean meat percentage and LMPH, while LMPH was correlated positively with carcass lean meat, SALT1, SALT, and weight losses. The GWAS detected genome-wide association for 12 single nucleotide polymorphisms with Ferrochelatase activity. The results obtained in this preliminary study were achieved by combining innovative and non-destructive technologies for screening hams under processing, measures of enzymatic muscle properties relevant to dry-cured ham quality, and genomic information obtained through a GWAS. Additional studies carried out in a larger number of pigs have been planned to investigate the effect of gene variants of Ferrochelatase activity in the dry-cured ham's quality with main reference to colour development and to confirm the GWAS results obtained in this study.

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.

The Influence of the Type of Dry-Cured Italian PDO Ham on Cathepsin B Activity Trend during Processing

Cathepsin B activity was measured during processing in hams originating from the main Italian prosciutto PDOs: Parma, San Daniele and Toscano. Sixty-five heavy pig thighs, from sixty-five Italian large white x Italian Landrace pigs bred and slaughtered in the same conditions were considered. Five thighs represented the post-mortem control time. The other 60 were distributed one plant per PDO, following a balanced plan. The thighs were sampled at the biceps femoris in groups of four per plant in the following ripening phases: salting, resting, drying, greasing, end of curing. The activity of the Cathepsin B (U/g protein) was determined by means of fluorescence measurements. The Cathepsin B ripening trend of the various PDOs was significantly different, particularly during the initial and mid-curing stage. This activity correlates with the proteolysis index through a PDO dependent pattern, indicating that different processing conditions can influence the quality of prosciutto, since they determine its biochemical development.

Influence of Muscle Type on Physicochemical Parameters, Lipolysis, Proteolysis, and Volatile Compounds throughout the Processing of Smoked Dry-Cured Ham

The influence of muscle type (biceps femoris, BF and semimembranosus, SM) on physicochemical parameters, volatile compounds, and the extent of proteolysis and lipolysis during the manufacturing of smoked dry-cured ham was investigated. A total of fifty smoked hams were sampled: raw ham, after salting, smoking, drying, and ripening. Almost all physicochemical parameters were affected by muscle type, manufacturing stage and their interactions. SM had lower water, ash, NaCl content, and water activity (aw), while fat and protein content were higher after ripening compared to BF. BF showed higher L*a*b* values compared to SM. The results of texture profile analysis showed that almost all analyzed parameters were influenced by muscle type and production stage. A total of 88 volatile compounds were identified, showing an increase in its number during processing: 31 volatile compounds were identified in raw ham and 72 after the ripening phase. Aldehydes and phenols were the predominant groups of compounds, followed by alcohols, ketones, aromatic hydrocarbons, aliphatic hydrocarbons, esters, and terpenes. Muscle type and production phase significantly affected lipid oxidation and the index of proteolysis: in SM, thiobarbituric acid reactive substances (TBARS) increased faster than in BF, while proteolysis had an opposite effect and was more pronounced in BF.

Instrumental texture analysis on the surface of dry-cured ham to define the end of the process

The end of the elaboration process of dry-cured ham is currently decided by product weight loss and/or by an expert who carries out an evaluation of the tactile texture on the surface. The objective of this study was to define the optimal measurement conditions of an instrumental texture analysis on the surface of the dry-cured ham (ITAS), to define the end of process. 120 dry-cured hams were classified by experts into Hard (appropriate) or Soft (non-appropriate) texture groups and used to perform compression tests using different probes on three anatomical positions. Results showed that the small probe in position 2 gave the most discriminant conditions, providing representative information of the internal texture. Although classification using only weight loss was possible with an accuracy rate of 80.4% or 66.7% depending on the weight loss, the maximum classification accuracy was obtained when using ITAS in combination with weight loss. Further studies at industrial level are needed.

Water status in meat from pig breeds strongly differing in growth performances

This research compared the distribution and mobility of water in the longissimus thoracis muscle of 51 Apulo-Calabrese and 52 crossbred pigs differing in growth performances. The Apulo-Calabrese and crossbreed pigs were fed the same diet and slaughtered at 135 and 155 kg live weight, respectively. Besides meat quality measurement, water status was assessed from transverse relaxation time (T₂) weighted signals registered by Time Domain Nuclear Magnetic Resonance (TD-NMR). A mixed model indicated that Apulo-Calabrese pigs had higher a* (P-value < 0.0001), chroma (P-value < 0.0001) and total intensity (P-value = 0.011) values. A Principal Component Analysis showed that the samples from Apulo-Calabrese had higher scores along Principal Component (PC) 2 (P-value = 4.07 × 10^-5) and lower scores along PC3 (P-value = 1.50 × 10^-7). However PC2 and PC3 explained a low fraction of the total variance, suggesting that few differences characterize meat quality traits of the two genetic types.

Effects of increased space allowance on animal welfare, meat and ham quality of heavy pigs slaughtered at 160Kg

Sixty barrows (Body Weight–BW- range: 23.9–160 kg) were allotted to two experimental groups (6 pens of 5 pigs each): the control group was kept at a space allowance of 1m²/head; the second group was kept at 1.3m²/head. Behaviour, growth parameters, carcass and meat quality were assessed, as well as fat and cured ham quality. Results showed that pigs raised at 1.3m²/head spent more time laying (particularly in lateral recumbency, P<0.01 and P<0.001, respectively) compared to pigs kept at lower space allowance. They also reduced the aimless exploration of the slatted pen floor (P<0.001) and increased overall expression of other, mainly active, behaviors (e.g., drinking, walking and standing, P<0.01). Pigs raised at 1.3m^2/head showed higher final BW (P = 0.02), more favourable Average Daily Gain (ADG) and gain-to-Feed ratio (G:F) both during the last period of the trial (P<0.05 for both parameters) and over the entire trial (P = 0.01 for both parameters). No significant difference was observed between groups for carcass traits and the main meat quality attributes. Subcutaneous fat from green hams had higher α-linolenic acid content (P<0.01) in the group reared at greater space allowance. Green hams from this group lost less weight at trimming (P<0.01) and the resulting cured hams received better sensory evaluations (P<0.05). No difference was observed in fatty acid composition and unsaturation levels of the subcutaneous fat from cured hams. Our data suggest that heavy pigs intended for Parma ham would benefit from the adoption of higher individual floor space allowances, both in terms of animal welfare (increased possibility to rest) and of productive parameters, without having any detrimental effect on the suitability of the thighs for dry-curing or on the quality of the final product.

Effects of single nucleotide polymorphisms and haplotypes of the protein kinase AMP-activated non-catalytic subunit gamma 3 (PRKAG3) gene on production, meat quality and carcass traits in Italian Large White pigs

PRKAG3 is a major gene for meat quality and production in pigs. In this study, we investigated two single nucleotide polymorphisms (SNPs) of the PRKAG3 promoter region (g.-995A>G and g.-311A>G) in 381 pigs of different breeds. Association between these SNPs and three major haplotypes, constructed including other three substitutions (c.89C>A, c.154A>G and c.595G>A) and different traits (meat quality parameters: pH_2h, pH_u, glycogen and lactate content, glycolytic potential and cathepsin B activity of Semimembranosus muscle; estimated breeding values and random residuals for growth performances and carcass traits) were analysed in 271 Italian Large White performance tested pigs. A significant effect (P=0.043) of the g.-995A>G SNP on cathepsin B activity and a suggestive effect (P=0.067) of the g.-311A>G SNP on pH_u were found. The haplotype [g.-995G:g.-311G:c.89A:c.154G:c.595G] was associated with pH_u (P=0.024), glycolytic potential (P=0.040) and cathepsin B activity (P=0.086). This study on haplotypes, including promoter region SNPs, contribute to explain the effect of this gene on meat quality traits in pigs.

Effect of Lactobacillus acidophilus Bauer and Bifidobacterium animalis ssp. lactis BB12 on proteolytic changes in dry-cured loins

The effect of the potentially probiotic bacteria strain of Lactobacillus acidophilus Bauer and probiotic bacteria Bifidobacterium animalis ssp. lactis BB12 on proteolytic changes of proteins in dry-cured loins during fermentation and cold storage was studied. Results of the conducted tests demonstrated that the use of probiotic bacteria for the production of dry-cured meats impacts the generation of products of protein proteolysis with high antioxidant activity. The highest antioxidant activity of peptides after fermentation and cold storage was observed in the loin with the strain B. animalis ssp. lactis BB12 and the loin with the mixture of strains L. acidophilus Bauer and B. animalis ssp. lactis BB12. Qualitative analysis of peptides demonstrated that peptides with weight below 3.5 kDa are characterized by the highest capacity of quenching the ABTS cation radical, including the peptides in loins with the strain B. animalis ssp. lactis BB12.

Association study between single nucleotide polymorphisms in porcine genes and pork quality traits for fresh consumption and processing into Italian dry-cured ham

Single nucleotide polymorphisms (SNPs) of six genes (TTN, PRKAG3, CAST, CTSB, CTSF, and MYPN), known for associations with carcass and meat quality traits, post mortem proteolysis, were screened in a commercial crossed population of 368 heavy pigs (Large White x Landrace)×Duroc, reared according to the rules of Italian Protected Designation of Origin (PDO) dry-cured ham. Carcass, longissimus thoracis et lumborum muscle (LTL), and green ham traits were obtained after slaughtering, main weight losses of dry-cured hams were collected during processing. The results showed the impact of CAST variants on carcass weight, of CTSF on LTL tenderness, ham weight and fatness, of PRKAG3 and TTN on ultimate pH, hamweight. This study, while confirming significant associations between SNPs of genes and qualitative traits of carcass, longissimus and ham, supports CTSF as candidate gene suitable for fresh consumption purpose (tenderness of longissimus at 24h post mortem), and for dry-cured ham processing (higher thickness of ham subcutaneous fat).

Effect of progressive reduction in crude protein and lysine of heavy pigs diets on some technological properties of green hams destined for PDO dry-cured ham production

In order to investigate the effects of dietary crude protein (CP) and lysine (Lys) content on some technological properties of green hams destined for Protected Designation of Origin (PDO) dry-cured ham, green hams visual appraisal scores, thickness, iodine number and fatty acid composition of subcutaneous fat, and ham weight losses during seasoning (SL) were assessed. The green hams were obtained from 233 pigs fed four diets containing 140 to 110g/kg CP and 6.5 to 5.3g/kg total Lys from 90 to 165kg body weight. A reduction in dietary CP and Lys of up to 20% compared with conventional feeds led to a 15% increase in the thickness of the subcutaneous fat, a 5% decrease in linoleic and polyunsaturated fatty acids in subcutaneous fat and a 7% decrease in SL. A 20% reduction of CP and Lys in diets for finishing pigs has positive effects on the technological properties of green hams destined for PDO dry-cured ham production.

Effect of vaccination against gonadotropin-releasing hormone (GnRH) in heavy male pigs for Italian typical dry-cured ham production

The aim of this study was to evaluate immunocastration (vaccination against GnRH using Improvac® vaccine), as an alternative to surgical castration in heavy male pigs (average live weight 165 ± 10 kg), used in the production of Italian typical dry-cured ham. A total of 60 Landrace × Large White male pigs were assigned to three groups of 20 units, including one group of surgically castrated (SC), and two of immunocastrated pigs, with two (IC2) or three (IC3) vaccine treatments, respectively. The groups were compared for green ham traits, processing weight losses, chemo-physical, and sensory properties of dry-cured hams. While IC3 were not different (P>0.05) from SC group, IC2 hams were found to differ (P<0.05) both from SC and IC3 groups in ham traits, final weight losses, texture and sensory boar taint in finished hams. Therefore, vaccination with three doses could be taken into account to control boar taint in the manufacturing of typical Italian dry-cured ham.

Factors in pig production that impact the quality of dry-cured ham: a review

This study reviews the factors of pig production that impact the quality of dry-cured ham. When processing is standardized, the quality of the final dry-cured product is primarily determined by the quality of the meat before curing (green ham). This has been defined as the aptitude for seasoning and is determined by the green ham weight, adipose tissue quantity and quality, meat physico-chemical properties and the absence of visual defects. Various ante-mortem factors including pig age and weight, genetic type, diet, feeding strategy and slaughter conditions determine green ham properties such as the dynamics of water loss, salt intake and, as a consequence, proteolysis and lipolysis. Muscle conditions (pH, salt concentration, water content and availability, temperature) influence enzymatic activity and development of characteristic texture and flavor. Generally, hams of older and heavier pigs present better seasoning aptitude because of higher adiposity. Adiposity is also positively correlated with fat saturation, which is desired to avoid rancidity and oiliness. The fatty acid profile of tissue lipids can be manipulated by diet composition. Feeding strategy affects tissue accretion and protein turnover, thus directly impacting proteolysis. With respect to the impact of pig genotype on dry-cured ham quality, local breeds are generally considered more suitable for producing quality dry hams; however, the majority of dry-cured hams on the market today are from modern pig breeds raised in conventional systems, providing lean hams. The importance of all these factors of pig production is discussed and synthesized, with an emphasis on the main difficulties encountered in dry-cured ham production.

Carcass and ham quality characteristics of heavy pigs from different genetic groups intended for the production of dry-cured hams

Carcass and ham quality characteristics of pig populations divided by harvest weights--HW (130 and 160 kg) were evaluated to determine the effects of gender (barrows and gilts) and distinct genetic groups--purebred (DUDU) and crossbred Duroc (DULA, DUWI and DULL) as well as purebred Large White (WIWI) on the suitability for use in dry-cured ham production. At 130kg, DUDU pigs yielded the highest fat thickness of the ham (P<0.01) and an intramuscular fat content (IMF) of 3.15% in Semimembranosus muscle (SM). DUDU pigs also had a SM pH(u) of 5.7. This genetic group met the specifications for dry-cured ham production. No differences could be found in meat quality characteristics between genetic groups harvested at 160 kg. However at this HW, gilts produced significantly (P<0.05) heavier and leaner hams compared to barrows.

Use of Magnetic Resonance Imaging for monitoring Parma dry-cured ham processing

Protocols were developed to apply Magnetic Resonance Imaging (MRI) to the dry-curing of Italian Parma ham. NMR relaxation analyses were performed on dry-cured hams at different processing stages to evaluate the ranges of variation of (1)H relaxation times T(1) and T(2) in representative ham muscle tissues, due to dehydration and salt uptake. MRI maps of the same ham sections were acquired, allowing T(1) and T(2) average values to be computed in selected Regions of Interest (ROI) inside muscle Semimembranosus, Semitendinosus and Biceps femoris. Chloride and moisture were determined by conventional chemical methods on the same ROIs, and MRI T(1) and T(1)/T(2) ratio were selected in a model (R(2)=0.90, P<0.05) fitting the salt content of the analysed muscle cores. Short Time Inversion Recovery (STIR) sequences were also applied to green and cured hams, but on fresh samples only, a bright image, displaying a clear separation between lean and fat tissue, was obtained.

Effect of extended aging of parma dry-cured ham on the content of oligopeptides and free amino acids

The effect of the dry-curing processing time on the release of oligopeptides and amino acids was evaluated with 158 Parma hams subdivided into three groups: (1) traditional processing (450 days); (2) extended processing (570 days); and (3) extended aging (690 days). Most of the oligopeptides and free amino acids detected increased up to the last deadline (690 days); a sharp increase of peptides below 400 Da was the main change in most aged hams. In particular, gamma-glutamyl dipeptides showed a remarkable increase during ham extended aging, acting like permanent taste-active compounds, being unsuitable for further enzymatic breakdown. The pH of fresh hams showed negative relationships (P < 0.001) with most peptides. With regard to free amino acids, the pattern was modified by different processing lengths, together with their taste categories, so that the amino acids having monosodium glutamate-like and bitter tastes were enhanced in more aged hams.