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%).     

High pressure applied to frozen ham at different process stages. 2. Effect on the sensory attributes and on the colour characteristics of dry-cured ham

This paper describes the effect of high pressure (400MPa and 600MPa) applied to frozen hams at early stages of the dry-cured ham process: green hams (GH) and hams at the end of the resting stage (ERS), on the appearance, some texture and flavour parameters and on the instrumental colour characteristics of dry-cured hams. Pressurized hams showed slightly lower visual colour intensity than the control ones. In general, pressurization did not have a significant effect on the flavour characteristics of the final product. The 600-MPa hams from the ERS process showed significantly lower crumbliness and higher fibrousness scores than the control and the 400-MPa hams. However, none of these differences were enough to affect the overall sensory quality of the hams negatively. Regarding instrumental colour characteristics (L(?)a(?)b(?)), an increase in lightness was observed in the biceps femoris muscle from GH hams pressurized at 400MPa and 600MPa but not in the ERS hams.     

Effect of irradiation on colour and lipid oxidation of dry-cured hams from free-range reared and intensively reared pigs

The effect of irradiation dose (0, 5 and 10 kGy) of vacuum-packaged Iberian dry-cured ham slices from pigs fed on concentrate (CON) or free-range reared (FRG) was studied in relation to TBA-RS, hexanal content and instrumental colour changes. TBA-RS values increased after irradiation in the two sets of hams and the increase was dose-dependent. FRG samples showed higher TBA-RS values than CON samples in all treatments, although differences in the rate of formation of thiobarbituric acid-reactive substances were different in the two types of hams, being higher in CON samples than in FRG ones. Irradiation of dry-cured ham slices significantly increased hexanal contents in both sets of hams. Irradiation produced statistically significant increases in vacuum-packed dry-cured ham slices lightness (L^⁎-value), yellowness (b^⁎-value) and chroma (C^⁎-value). Irradiation resulted in significantly lower hue angle (h°) values and higher a^⁎-values in both sets of hams indicating a redder colour of irradiated samples than non-irradiated, and these changes were greater in FRG samples than in CON samples. Differences in composition characteristics of raw material could play an important role in the irradiation-induced changes on colour and lipid oxidation of vacuum-packaged dry-cured ham slices.Industrial relevanceIberian ham is dry-cured meat product with a high sensory quality due to pig fattening feature and the characteristics of its processing. Both factors lead to a product with characteristic cured red colour of the lean, an intense, characteristic and pleasant flavour, unique in dry-cured hams, derived from intense lipid oxidative phenomena. New commercialization formats of dry-cured Iberian hams include vacuum-packed sliced ham. Although the low Aw, NaCl and nitrite/nitrate contents make dry-cured ham not adequate for the growth of pathogens and spoilage microorganisms (cocci gram+ and yeast), those may be present on the surface of whole hams and reach the sliced product during the final boning, slicing and packaging operations even with the observation of strict hygienic procedures despite the implementation of modern technologies and HACCP systems, constituting a permanent risk of contamination. Dry-cured Iberian ham, as a result of its chemical characteristics, is a product with a long shelf-life at refrigeration temperature, however the risk of spoilage or pathogen growth could increase in the case of temperature abuse for a long stored period. Finally, due to health concerns, salting and curing process of dry-cured Iberian hams tend to a reduction in levels of NaCl and nitrite used. That could increase the risk associated to microorganism presence in dry-cured sliced hams. The use of irradiation could minimizes this risk, however irradiation could have important effects on overall quality of dry-cured Iberian products in which colour and extent of lipid oxidation and lipid oxidation-derived volatile compounds play an important role in consumer acceptation of the product.     

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.     

Data Mining on MRI-Computational Texture Features to Predict Sensory Characteristics in Ham

In this study, data mining technique was applied on computational texture features obtained from the analysis of magnetic resonance imaging (MRI) of hams, with the main objective of determining sensory attributes of dry-cured ham non-destructively. For that, fresh and dry-cured hams were scanned and then the MRI images were analyzed by three methods of computational texture features. Data mining was applied on the computational texture features from fresh and dry-cured hams for obtaining prediction equations of the sensory attributes of dry-cured hams. The correlation coefficient (R) was used to analyze the results. Accurate prediction was found for 13 sensory attributes as a function of computational texture features of fresh ham, and three from dry-cured ham. In addition, a sensory analysis of dry-cured hams was also carried out to validate the predicted results. Similar values were found between the predicted attributes and those determined by sensory analysis. Thus, it is possible to predict sensory attributes of dry-cured hams by applying data mining on computational texture features of MRI from fresh and dry-cured hams. This supposes the chance of determining non-destructively sensory attributes of dry-cured hams, even before the curing process starts.     

不同地域典型干腌火腿肌原纤维蛋白的氧化特性及体外消化性对比

为比较几种典型干腌火腿的可消化吸收性,以巴马火腿、金华火腿、宣威火腿、帕尔玛火腿为原料,研究4 种干腌火腿的肌原纤维蛋白表面疏水性、巯基和二硫键含量、超微结构、蛋白降解程度、消化前后粒径及体外消化率。结果表明：金华火腿肌原纤维蛋白的表面疏水性显著高于巴马、宣威、帕尔玛火腿（P＜0.05）。微观结构分析显示金华火腿肌原纤维蛋白交联和聚集程度最低,肌原纤维排布更为伸展;帕尔玛火腿聚集程度最大,呈现明显聚集状。十二烷基硫酸钠-聚丙烯酰胺凝胶电泳谱图显示金华火腿肌原纤维蛋白在体外消化过程中大幅降解,促进了肌原纤维蛋白粒径的降低。体外模拟消化结果表明,经胃蛋白酶、胰蛋白酶及α-凝乳蛋白酶作用后,金华火腿肌原纤维蛋白水解速率最高（P＜0.05）;帕尔玛火腿肌原纤维蛋白水解速率最低（P＜0.05）。这表明疏水基团的暴露和蛋白结构的伸展为消化酶提供了更多的识别位点,促进了金华火腿中肌原纤维蛋白的水解。综上,肌原纤维蛋白的氧化程度显著影响蛋白的体外消化率。     

Lean colour of green and matured Parma hams: Comparative evaluation and technological relevance of sensory and objective data

Research has been conducted on the relationship between sensory evaluation and objective measurement of pork colour. The study also investigated the relationship between the colour of fresh meat and the colour of matured hams. Sensory evaluation was carried out at 24 h post mortem on the freshly cut surfaces of green hams trimmed for Parma ham production. Objective measurements were performed at the same time on Semimembranosus and Biceps femoris muscles with a Minolta Chromameter Reflectance II CR200/08. Cold carcass weight, lean content, trimmed ham weight, 45 min and 24 h post mortem pH of Semimembranosus muscle were also recorded. The hams were processed according to Parma ham technology. Weight losses at standard processing times were collected. At the end of processing a sample of about one-third of the hams was evaluated for internal lean colour and lean firmness both by sensory panel and objective measurements. Proximate composition was also determined. The results showed highly significant relationships between colour sensory scores and the coordinates L (?), b (?) and hue of the C.I.E. L (?)a (?)b (?) colour system. Among the other parameters measured on fresh meat only 24 h pH was related at a very significant level with sensory and objective colour values. Correlation coefficients were generally higher for Semimembranosus than Biceps femoris. Matured ham colour was linked with fresh meat sensory judgements, L (?), hue and a (?) values. The relationship, though, was not sufficiently strong for use in predicting the colour of matured hams from green ham characteristics. Processing appears to have a positive effect on the colour of pale meat. Weight losses were mainly linked with lean meat content; other quality attributes being less important. Lean firmness of matured hams was related to the colour and pH of the fresh meat.     

不同来源和年份诺邓火腿的理化和呈味性质

为研究市售常见诺邓火腿的差异,对具有地域特色的诺邓火腿进行综合评价。以洋三元白猪、诺邓黑猪为原材料,按照诺邓火腿工艺加工1、3 年火腿,测定其理化指标、质构特性和游离氨基酸含量,并用电子舌分析其滋味特性差异。结果表明：4 组火腿质地存在明显差异;4 组火腿中均分离出18 种游离氨基酸,精氨酸含量最丰富,亮氨酸、赖氨酸和谷氨酸次之;洋三元白猪火腿（W组）的游离氨基酸含量高于诺邓黑猪火腿（B组）,B组的鲜味氨基酸相对含量高于W组,氨基酸的释放量可明显将1 年和3 年的火腿区分开;电子舌结果表明,B1组的滋味丰富性最大,B3组的咸味最大但鲜味最小,W1组的鲜味较大但丰富性较小,W3组的咸鲜味和丰富性适中。综上,鲜味、丰富性和咸味是诺邓火腿重要的味觉指标,诺邓黑猪火腿滋味较为丰富,B3组硬度、咸味最大,加工过程中要控温控湿。     

Proteomic analysis of water soluble and myofibrillar protein changes occurring in dry-cured hams

The myofibrillar fraction of raw ham muscles and dry-cured hams with different ripening times was extracted in denaturing and reducing conditions and subjected to two-dimensional gel electrophoresis. The two-dimensional maps gave overall pictures of the already noted progressive disappearance of actin, tropomyosin and myosin light chains during ripening. In addition, two fragments from Myosin Heavy Chain proteolysis, marked as myosin chain fragments MCF1 and MCF2, were identified by immunodetection and matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS). Furthermore, a new form of actin on two-dimensional gel was identified by MALDI-TOF peptide mapping. In 12-month-old dry-cured ham, most myofibrillar proteins were completely hydrolyzed. At this stage of ripening, in fact, in some Parma and S. Daniele dry-cured ham samples, myosin heavy chain fragments and other unidentified neo-formed spots were found. Some of the sarcoplasmic proteins in water extracts from pork meat markedly decreased in amount or disappeared totally, during ripening. Surprisingly, two-dimensional gel electrophoresis maps of the water soluble protein fraction from dry-cured ham showed the presence of two spots identified as tropomyosin α- and β-chain. This result suggests that some of the saline soluble myofibrillar proteins can disappear from this fraction because of salt solubilization and not due to complete enzyme action. Two-dimensional gel electrophoresis (2-DGE) has proved a powerful tool to evaluate the enzymatic susceptibility of meat proteins and the evolution of protein map fragmentation throughout ripening process as well as a means of obtaining a standard fingerprinting map characterizing the final product.     

Influence of dietary fat, on fatty acid composition and sensory properties of dry-cured Parma ham

A feeding trial with 27 pigs was performed in order to estimate the effect of different dietary fats on the fatty acid composition, flavour and sensory properties of dry-cured Parma hams, ripened for 16 months. The animals received a pelleted diet supplemented with different fat sources: tallow (TA), corn oil (CO), and rapeseed oil (RO). The sensory quality of the hams was evaluated by means of sensory analyses and by instrumental procedures such as gas chromatography-mass spectrometry of the volatile aroma compounds. A treatment effect was detected for linolenic acid in RO vs. CO and TA hams (P<0.01) and for MUFA content (P<0.01) that was higher in RO and TA compared with CO. The results of panel test showed a significant difference (P<0.05) between TA vs. CO and RO hams. Volatile compounds showed limited differences even if in CO group the amount of singular compound is higher than TA and RO.     

Oligopeptides and free amino acids in Parma hams of known cathepsin B activity

Sixteen Parma hams were manufactured following regular standard procedures up to the 13th month of processing and then divided into two groups according to established levels of cathepsin B activity in fresh hams. Each group was selected in order to include the same number of hams with low or high cathepsin B activity. The two groups were further split to be kept for an additional month at two different temperatures (18 and 26 °C) and then analysed for proximate composition, free amino acids and oligopeptides (MW<500 Da). All hams were analysed by sensory analysis (panel test) to be scored for saltiness, bitterness and the flavour of “ageing”. Fresh hams with higher cathepsin B activity were shown by means of two-way ANOVA to yield dry-cured hams more proteolysed (P<0.01), while the higher temperature of the final ageing period seemed to play a major role in lowering ham dryness. Bitterness was particularly well perceived in most proteolysed hams and it was significantly related to the higher amounts of lipophilic amino acids and lipophilic oligopeptides (identified by mass spectrometry), in agreement with the literature. Thus, the endopeptidase activity in fresh hams, together with the presence of specific lipophilic amino acids and oligopeptides in dry-cured hams, can be regarded as a molecular marker of bitter taste development.     

Postmortem meat quality and sex affect textural properties and protein breakdown of dry-cured ham

Texture measurements by instrumental texture profile analysis (TPA) and protein degradation analysis by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) were performed on 30 dry-cured hams resulting from four different post-mortem meat qualities categories (PSE, RSE, RFN and DFD). The main differences were observed in dry-cured hams from PSE and RFN meat qualities. Penetration force (80%), hardness, springiness, cohesiveness and chewiness, were significantly lower (P<0.05) in PSE than in RFN quality classes. The rate of the ripening process was affected as a higher proteolysis and absence of fragments at 150 and 85 KDa in PSE in relation to RFN classes, and with an intermediate proteolysis of RSE and DFD classes. The effect of sex was observed as a significant (P<0.05) low hardness in the hams obtained from female pigs. The duration of the ripening, for a better uniformity in dry-cured ham production, should be adapted to the initial pH and to drip loss parameters of the raw material.     

Factors affecting acceptability of dry-cured ham throughout extended maturation under "bodega" conditions

The evolution of biochemical, instrumental colour and texture, sensory parameters and consumer acceptability of 12-month dry-cured hams maintained up to 26 months under “bodega” conditions (18 °C, 75% relative humidity) was assessed, in order to investigate the influence of extended ripening on their sensory characteristics and acceptability. Results demonstrated that ham acceptability showed no significant differences (p > 0.05) from 12 to 22 months, while it decreased significantly (p < 0.05) until 26 months. Principal component analysis of all data brought about a comprehensive explanation of the biochemical, instrumental and sensory parameters involved in the acceptability decrease. In fact, high pastiness and adhesiveness values, as measured by both sensory and instrumental methods, appeared to be most related to decreasing acceptability. Those attributes were the result of an excessive proteolysis, as revealed by biochemical maturation indices.     

基于智能感官与人工感官评价的中国三大干腌火腿风味特性分析

以我国三大干腌火腿金华火腿、宣威火腿和如皋火腿三个不同年份或等级的火腿为研究对象,分别采用人工感官评价和电子鼻、电子舌智能感官技术分别对香气与滋味进行研究。人工感官评价结果显示,肉香味、腌制味和油脂香是三大火腿的特征香气,如皋和金华火腿中2年/优级和3年陈/特级的干腌火腿较于1级/1年陈具有更加浓郁的肉香,而1年陈/1级火腿的酸味更为明显。电子鼻和电子舌数据的主成分分析(Principal component analysis,PCA)结果表明,不同干腌火腿样品均能实现良好区分。1年陈/1级与2年/优级、3年陈/特级干腌火腿气味轮廓相差较远,金华火腿与宣威2、3年陈的火腿香气和滋味轮廓均比较接近。采用软独立建模分类法(Soft independent modeling class analogy,SIMCA)构建了干腌火腿的判别模型,以三个产地最优干腌火腿为标准样品的等级鉴别模型能够实现对其他年份干腌火腿的有效判别。说明不同年份的火腿风味变化呈现一定规律,可利用智能感官技术对火腿进行快速有效的等级鉴别。     

Identification and significance of the N-terminal part of swine pyruvate kinase in aged Parma hams

Within a project aimed at studying the peptide fraction in dry-cured Parma hams, a peptide was purified by means of reversed phase-high performance liquid chromatography (RP-HPLC) and identified by its molecular mass and amino acid sequence analysis. The peptide showed a very high degree of homology with the N-terminal part of different mammalian pyruvate kinases reported in databases and was accordingly identified as the N-terminal part of swine pyruvate kinase, whose sequence had never been reported before. The peptide was determined quantitatively by comparison with a suitable internal standard (Phe-Phe) in commercial ham samples with different age degrees. The peptide was found to be ubiquitous in Parma ham and its amount to increase during ageing even if a large variability was found within each assayed maturing time. The correlation found with the ham proteolysis degree (P<0.01) suggests that this peptide is related to the endopeptidasic activity. The peptide did not show a significant relationship with bitterness perception in assayed dry-cured ham, in agreement with the hypothesis that this taste is more related to free amino acids and low molecular weight peptides.     

Relationships of genotype and slaughter time with the appearance and texture of dry-cured hams

The influence of genetics and slaughter time on the sensory characteristics of dry-cured hams was studied. To this end, 341 dry-cured hams, selected from 1257 pigs from five different crosses, including Duroc, Landrace and Large White, in five slaughters distributed over a year (namely, December 2000, March, April, July and November 2001) were sensorially evaluated according to the ISO 8586-2:1994. The sensory parameters assessed were pastiness, softness, colour, ring colour, crusting and marbling. Analysis of the results revealed that both the genetics and slaughter time had a significant effect on the dry-cured ham quality. Thus, warmest months provide dry-cured hams of the highest quality, but with a higher incidence of crusting. Dry-cured hams with the best sensory evaluation for texture and colour were from crossbreed A [(LR × LW) × DU]; while crossbreed D [(LR × LW × DU) × DU] provided the highest percentage of faulty dry-cured hams, except for incidence of crusting. Other parameters, such as the ham weight, relationship between salting days and ham weight, pH before salting and total weight loss, also influenced the properties of the end-product.     

The effect of green ham pH and NaCl concentration on cathepsin activities and the sensory characteristics of dry-cured hams

There is a tendency to reduce the amount of NaCl in the manufacturing process of Spanish dry-cured ham. NaCl, pH and temperature determine the stability of this product. This study was concerned with the evaluation of green ham pH and sodium chloride concentration on cathepsin activities, physico-chemical parameters and sensory characteristics of dry-cured hams. Two different amounts of salt (55 and 80 g kg⁻¹) and two different pH levels (pH at 24 h post mortem <5·8; pH at 24 h post mortem >6·2) were used. Physico-chemical composition, cathepsin activity and a number of sensory parameters were evaluated. Hams with high pH displayed lower cathepsin activity, NPN, saltiness and hardness whereas the levels of brightness, crumbliness, pastiness and adhesivity were found to be higher than in normal hams. A high level of salt produced greater cathepsin B and B+L activity and lower pastiness and adhesivity than the samples with a low NaCl level. © 1998 SCI.     

The effects of castration on the eating quality of dry-cured ham

The influence of the castration of entire male pigs on the eating quality of dry-cured ham was evaluated. Forty-eight dry-cured hams (435-day aged) were studied from entire and castrated males of two different crossbreeds. The proximate composition of the meat and the androstenone, indole and skatole fat content were determined. The entire hams were classified according to the androstenone and skatole content. Sensory analysis was carried out by a trained panel, evaluating marbling, juiciness, saltiness, graininess, toughness, overall flavour, boar odour and boar flavour. Also carried out was a preference and acceptability paired test by consumers. Castration increased meat fattening and reduced the androstenone and skatole levels of the fat. Significant differences (P<0.05) were found between entires and castrates for the average values given in all the sensory attributes studied. The dry-cured ham from castrates was scored as more flavoured, more marbled and softer. It was also perceived as less grainy, less salty and having less boar odour and flavour. The sensory perception of boar odour was more intense than that of flavour in dry-cured ham and appears to be related to the level of androstenone and skatole in fat. Dry-cured ham from castrated males was also more accepted and more preferred by consumers, especially women and habitual consumers. Castration of male pigs contributes to improve the quality of dry-cured ham. The rejection caused by boar odour and flavour is reduced, improving the overall flavour, texture and juiciness. In addition, the saltiness is less pronounced in ham from castrates. For this reason, the production of high quality dry-cured ham will have to shoulder the extra costs associated with processing castrated pigs.