Reduction of NaCl content in restructured dry-cured hams: Post-resting temperature and drying level effects on physicochemical and sensory parameters

The effects of post-resting temperature (5 °C, 15 °C and 25 °C) and drying level (low and high, corresponding to final water contents (w/w) of 57% and 50%, respectively) were evaluated in restructured dry-cured hams. The reduction of NaCl content, with and without the addition of K-lactate as NaCl substitute was also evaluated. Physicochemical and instrumental colour and texture (Stress Relaxation test) parameters and sensory attributes were measured. The main effects of reducing the NaCl addition from 30 g/kg to 15 g/kg in restructured dry-cured hams were the reduction of saltiness and the increase of a_w, proteolysis and softness. The addition of K-lactate (19.7 g/kg) contributed to reduce these effects. Hams from high drying level had a longer processing time and a higher proteolysis index, but lower water content and harder texture. The increase of post-resting temperature to above 5 °C reduced the processing time and the metallic flavour, but at 25 °C restructured hams were spoiled. Therefore, the problems due to the reduction of NaCl to 15 g/kg in restructured dry-cured hams can be reduced by adding K-lactate and drying at 15 °C (after 3.5 months of resting at 5 °C) until a final weight loss of around 45% is reached.     

Processing of dry-cured ham in a reduced-oxygen atmosphere: Effects on physicochemical and microbiological parameters and mite growth

The effects of a reduced-oxygen atmosphere (ROA) ([O₂] < 4.5%) during part or the whole of dry-cured ham processing on microbiological and physico-chemical parameters and mite growth were investigated in two independent experiments. In Experiment 1, six hams were processed in ROA and six in air for 275 days; in Experiment 2, where lower RH was used, six hams were processed in ROA for 289 days, six for 214 days in air + 75 days in ROA, and six in air for 289 days. Microbiological analyses during the process and physicochemical analyses in final products were carried out. The use of ROA during the whole process increased the L∗ colour parameter in the subcutaneous fat and proteolysis index and decreased b∗ in the external part of the subcutaneous fat and cholesterol oxide concentration. The use of ROA combined with low RH retarded microbial growth and prevented mite growth.     

On-line application of visible and near infrared reflectance spectroscopy to predict chemical–physical and sensory characteristics of beef quality

The aim of this study was to assess the on-line implementation of visible and near infrared reflectance (Vis-NIR) spectroscopy as an early predictor of beef quality traits, by direct application of a fibre-optic probe to the muscle immediately after exposing the meat surface in the abattoir. Samples from M.longissimus thoracis from 194 heifers and steers were scanned at quartering 48 h postmortem over the Vis-NIR spectral range from 350 to 1800 nm. Thereafter, samples from M.longissimus thoraciset lumborum were analysed for colour (L^∗, a^∗, b^∗; 48 h postmortem), cooking loss (14 days postmortem), instrumental texture (Volodkevitch, 10 days aged meat; slice shear force, 3 and 14 days aged meat) and sensory characteristics. Vis-NIR calibrations, tested by cross-validation, showed high predictability for L^∗, a^∗ and b^∗ (R² = 0.86, 0.86 and 0.91; SE_CV = 0.96, 0.95 and 0.69, respectively). The accuracy of Vis-NIR to estimate cooking loss and instrumental texture ranged from R² = 0.31 to 0.54, suggesting relatively low prediction ability. Sensory characteristics assessed on 14 days aged meat samples showed R² in the range from 0.21 (juiciness) to 0.59 (flavour). Considering the subjective assessment of sensory characteristics the correlations of Vis-NIR measurements and several meat quality traits in the range from 0.46 to 0.95 support the use of on-line Vis-NIR in the abattoir. Improvement of predictability was achieved if only extreme classes of meat characteristics have to be predicted by Vis-NIR spectroscopy.     

Lipid oxidation and fishy odour development in protein hydrolysate from Nile tilapia (Oreochromis niloticus) muscle as affected by freshness and antioxidants

Lipid oxidation and fishy odour development in protein hydrolysate from fresh and ice-stored Nile tilapia (Oreochromis niloticus) were investigated. During iced storage of 18 days, heme iron content decreased with a concomitant increase in non-heme iron content (P < 0.05). Peroxide value (PV) and thiobarbituric acid reactive substances (TBARS) values increased. Phospholipid content decreased with a corresponding increase in free fatty acid content. The results suggested that lipid hydrolysis and oxidation took place during storage. When protein hydrolysates were produced from fresh and 18 days ice-stored Nile tilapia muscle, higher lipid oxidation and fishy odour/flavour along with higher amount volatile compounds were obtained in hydrolysate for unfresh sample (P < 0.05). However, the addition of mixed antioxidants during hydrolysis process markedly lowered lipid oxidation, b^∗, ΔC^∗, ΔE^∗ values, fishy odour/flavour as well as the formation of volatile compounds in the resulting hydrolysates prepared from both fresh and unfresh samples. Therefore, hydrolysate from Nile tilapia muscle with reduced fishy odour and lighter colour could be prepared by using fresh fish and incorporation of mixed antioxidants during hydrolysis.     

Combined effects of potassium lactate and calcium ascorbate as sodium chloride substitutes on the physicochemical and sensory characteristics of low-sodium frankfurter sausage

The purpose of this study was to evaluate the combined effects of sodium chloride (NaCl) substitutes, including potassium lactate (K-lactate) and calcium ascorbate (Ca-ascorbate), on the physicochemical and sensory characteristics of low-sodium frankfurter sausage (1.2% content of NaCl). Sausages produced with 40% substitution of NaCl with combined K-lactate and Ca-ascorbate showed a higher value of lightness (P < 0.001) than sausages containing 2.0% content of NaCl (control). However, the sensory panels were unable to distinguish a difference in color intensity between the control and treatment groups. Frankfurter sausages produced with 30% K-lactate and 10% Ca-ascorbate exhibited similar water-holding capacity, textural properties, and organoleptic characteristics (P > 0.05) when compared to control sausages. Thus, the use of these salt mixtures is a good way to reduce the NaCl content in meat products while maintaining the quality of meat products. These results may be useful in developing low-sodium meat products.     

Effect of iced storage of bigeye snapper (Priacanthus tayenus) on the chemical composition,properties and acceptability of Som-fug,a fermented Thai fish mince

The effect of iced storage of bigeye snapper (Priacanthus tayenus) on the chemical composition, properties and acceptability of Som-fug was investigated. During 15 days of iced storage, total volatile base (TVB), trimethylamine (TMA) and TCA-soluble peptide contents as well as thiobarbituric reactive substances (TBARS) of fish muscle increased continuously after 3 days of storage (p < 0.05). It was suggested that deterioration, protein degradation and lipid oxidation proceeded with increasing storage time. Som-fug prepared from surimi of bigeye snapper stored in ice for different times had similar pH, acidity and lactic acid bacteria count at the end of the fermentation (30 °C, 48 h). Generally, higher content of TCA-soluble peptides and higher TBARS were found in fermented Som-fug produced from bigeye snapper stored in ice for a longer time (p < 0.05). Hardness, adhesiveness, springiness, cohesiveness, and resilience of fermented Som-fug decreased with a concomitant increase in weight loss, released water and expressible water contents when fish kept for a longer time were used (p < 0.05). L^∗, a^∗, b^∗, whiteness and the likeness for appearance, colour, texture and flavour of Som-fug decreased when fish kept in ice for an extended time were used (p < 0.05). However, the taste likeness was not affected by iced storage time (p > 0.05). No differences in overall liking were noticeable when fish kept in ice for up to 12 days were used for Som-fug production (p > 0.05). Therefore, the quality of fish used as raw material should be an important factor in determining the characteristics of Som-fug.     

Classification of pre-sliced pork and Turkey ham qualities based on image colour and textural features and their relationships with consumer responses

Images of three qualities of pre-sliced pork and Turkey hams were evaluated for colour and textural features to characterize and classify them, and to model the ham appearance grading and preference responses of a group of consumers. A total of 26 colour features and 40 textural features were extracted for analysis. Using Mahalanobis distance and feature inter-correlation analyses, two best colour [mean of S (saturation in HSV colour space), std. deviation of b∗, which indicates blue to yellow in L∗a∗b∗ colour space] and three textural features [entropy of b∗, contrast of H (hue of HSV colour space), entropy of R (red of RGB colour space)] for pork, and three colour (mean of R, mean of H, std. deviation of a∗, which indicates green to red in L∗a∗b∗ colour space) and two textural features [contrast of B, contrast of L∗ (luminance or lightness in L∗a∗b∗ colour space)] for Turkey hams were selected as features with the highest discriminant power. High classification performances were reached for both types of hams (>99.5% for pork and >90.5% for Turkey) using the best selected features or combinations of them. In spite of the poor/fair agreement among ham consumers as determined by Kappa analysis (Kappa-value < 0.4) for sensory grading (surface colour, colour uniformity, bitonality, texture appearance and acceptability), a dichotomous logistic regression model using the best image features was able to explain the variability of consumers’ responses for all sensorial attributes with accuracies higher than 74.1% for pork hams and 83.3% for Turkey hams.     

Classification of dry-cured hams according to the maturation time using near infrared spectra and artificial neural networks

An attempt to classify dry-cured hams according to the maturation time on the basis of near infrared (NIR) spectra was studied. The study comprised 128 samples of biceps femoris (BF) muscle from dry-cured hams matured for 10 (n = 32), 12 (n = 32), 14 (n = 32) or 16 months (n = 32). Samples were minced and scanned in the wavelength range from 400 to 2500 nm using spectrometer NIR System model 6500 (Silver Spring, MD, USA). Spectral data were used for i) splitting of samples into the training and test set using 2D Kohonen artificial neural networks (ANN) and for ii) construction of classification models using counter-propagation ANN (CP-ANN). Different models were tested, and the one selected was based on the lowest percentage of misclassified test samples (external validation). Overall correctness of the classification was 79.7%, which demonstrates practical relevance of using NIR spectroscopy and ANN for dry-cured ham processing control.     

The effect of high pressure and residual oxygen on the color stability of minced cured restructured ham at different levels of drying,pH, and NaCl

Color stability of minced cured restructured ham was studied by considering the effects of high pressure (HP) (600 MPa, 13 °C, 5 min), raw meat pH₂₄ (low, normal, high), salt content (15, 30 g/kg), drying (20%, 50% weight loss), and residual oxygen level (0.02%–0.30%). Raw hams were selected by pH₂₄ in Semimembranosus, mixed with additives, frozen, sliced, and dried by the Quick-Dry-Slice® (QDS) process followed by HP treatment or not (control). Packaging and storage simulated industrial packaging: modified atmosphere containing 80% N₂, 20% CO₂, and residual O₂ in one of three intervals: < 0.1%, 0.1%–0.2%, or 0.2%–0.3%, and retail storage conditions: chill storage, 12 h light, 12 h darkness. HP improved the stability of the redness of 20% QDS hams, while the stabilizing effect on 50% QDS hams was smaller, concluding that water has the dominating role. Raw meat pH₂₄, salt content, and residual oxygen level had varying effects on the stability of the red color.     

Apoptosis during postmortem conditioning and its relationship to duck meat quality

The aim of this work was to examine the relationship of skeletal muscle apoptosis and postmortem development of meat quality. Colour, cooking loss, myofibril fragmentation index (MFI) and shear force of duck breast and thigh meat postmortem were measured, and changes of positive nuclei were assessed with Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphophate nick end-labelling method (TUNEL). Correlation analysis revealed that apoptosis were positively correlated with colour (L^∗, a^∗ and b^∗), cooking loss and MFI (P < 0.05), while it is negatively correlated with shear force (P < 0.05). Our results indicate the growing level of duck skeletal muscle cell apoptosis was associated with the postmortem development of meat quality traits such as meat colour, water holding capacity and tenderness.     

High pressure effect on the color of minced cured restructured ham at different levels of drying, pH, and NaCl

Color changes of minced cured restructured ham was studied considering the effects of high pressure (HP) treatment (600 MPa, 13 °C, 5 min), raw meat pH₂₄ (low, normal, high), salt content (15, 30 g/kg), and drying (20%, 50% weight loss). Raw hams were selected based on pH₂₄ in Semimembranosus, mixed with additives, frozen, sliced, and dried using the Quick-Dry-Slice® process. Meat color (CIE 1976 L*a*b*) and reflectance spectra were measured before and after HP treatment. HP significantly increased L*, decreased a*, and decreased b* for restructured ham dried to 20% weight loss, regardless of salt content and pH₂₄. L* and a* were best preserved in high pH/high salt restructured ham. HP had no effect on the color of restructured ham dried to 50% weight loss. HP had no effect on the shape of reflectance curves, indicating that the pigment responsible for minced cured restructured ham color did not change due to HP.     

A note on the relationships between cured-cooked and dry-cured ham processing yields

Right and left hams from 353 pigs slaughtered at around 100 kg body weight were processed into cured-cooked hams and dry-cured hams, respectively. Weights and yields at various stages of each process, carcass lean content and fresh meat quality traits were registered. Technological yield of cured-cooked processing (saleable cooked ham weight/defatted–deboned fresh ham weight) was more closely correlated to ultimate pH (r = 0.51, p < 0.001) than to carcass leanness (r = −0.13, p < 0.05) whereas the reverse situation – r = 0.15 (p < 0.01) and r = −0.62 (p < 0.001), respectively – was found for technological yield of dry-cured processing (saleable dry ham weight/trimmed fresh ham weight). The correlation between the two technological yields was significantly positive but of fairly moderate magnitude (r = 0.36). The correlation between the overall yields (saleable processed ham weight/entire fresh ham weight) of the two processes revealed to be very close to zero (r = −0.01).     

Sensory and texture properties of Italian typical dry-cured hams as related to maturation time and salt content

Maturing time and salt were fixed factors and fat was a covariate in a full factorial design study of sensory and texture properties of 36 dry cured hams. Samples were chosen to fit three ageing and salt classes. Differences (P < 0.05) in sensory scores were found between whole slices (with cover fat) and their biceps femoris (BF) counterparts, with sweet taste enhanced in whole samples and conversely unpleasant bitter taste more intense in BF portions. Increased ageing time resulted in better sensory profiles, as documented by greater scores (P < 0.05) for matured odour, matured taste and sweet taste, whereas salty taste was reduced. Decreased salt was associated with greater intensities (P < 0.05) of undesired green odour and taste. Based on chemical composition, the ham consistence appears improved by long-term dehydration, provided that protein breakdown is under control. It is concluded that for salt reduction of up to 25% to be achieved without negative side effects, extended ageing and restrained proteolysis are key factors.     

Near-infrared oximetry of three post-rigor skeletal muscles for following myoglobin redox forms

We investigated the response of frequency-domain multidistance (FDMD) near-infrared (NIR) tissue oximetry for detecting absolute amounts of myoglobin (Mb) redox forms and their relationship to meat colour stability. Four packaging formats were used to create different blends of Mb redox forms and meat colours during display. Changes in surface colour and subsurface pigment forms during simulated display time (0, 2, 4, and 10 d at 2 °C) were evaluated using surface reflecto-spectrophotometry (both L∗a∗b∗ and specific wavelengths) and FDMD NIR tissue oximetry. Data for both methods of direct measurement of oxymyoglobin and deoxymyoglobin were strongly related and accounted for 86–94% of the display variation in meat colour. Indirect estimates of metmyoglobin ranged from r² = 59–85%. It appears that NIR tissue oximetry has potential as a noninvasive, rapid method for the assessment of meat colour traits and may help improve our understanding of meat colour chemistry in post-rigor skeletal muscle.     

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.     

Use of viscera extract from hybrid catfish (Clarias macrocephalus × Clarias gariepinus) for the production of protein hydrolysate from toothed ponyfish (Gazza minuta) muscle

Proteolytic activity of viscera extract from hybrid catfish (Clarias macrocephalus × Clarias gariepinus) was studied. The optimal pH and temperature were 9.0 and 50 °C, respectively, when toothed ponyfish (Gazza minuta) muscle was used as a substrate. When viscera extract from hybrid catfish was used for the production of protein hydrolysate from toothed ponyfish muscle, extract concentration, reaction time, and fish muscle/buffer ratio affected the hydrolysis and nitrogen recovery (NR) (p < 0.05). Optimum conditions for toothed ponyfish muscle hydrolysis were 3.5% hybrid catfish viscera extract, 15 min reaction time and fish muscle/buffer ratio of 1:3 (w/v). High correlation between the degree of hydrolysis (DH) and NR (R² = 0.974) was observed. Freeze-dried hydrolysate had a high protein content (89.02%, dry weight basis) and it was brownish yellow in colour (L^∗ = 63.67, a^∗ = 6.33, b^∗ = 22.41). The protein hydrolysate contained a high amount of essential amino acids (48.22%) and had arginine and lysine as the dominant amino acids.     

High pressure induces changes in texture and microstructure of muscles in dry-cured hams

The objective of this paper was to study the changes in the microstructure of Semimembranosus and Biceps femoris muscles of dry-cured hams induced by high pressure (HP) processing and their relationship with the changes in texture. The HP treatment (500 MPa) decreased softness (Y₉₀) in both muscles. Both X-ray microcomputed tomography (μCT) and scanning electron microscopy (SEM) analysis showed differences in microstructure between muscles. Some μCT geometric parameters were negatively (structure thickness of fatty objects, structure separation of lean tissue) and positively (surface/volume and fragmentation index of fatty objects) correlated with hardness, but no one was significantly modified by HP treatment. SEM analysis showed that pressurization had a higher effect on BF muscle than on SM muscle.Industrial relevanceIn ham industry, high pressure (HP) processing is used to achieve the microbial safety of hams and to improve texture, especially in those hams with a reduced salt content. The data presented in this study contributes to the understanding of HP effect on textural traits at microstructural level.     

Effect of blending durum wheat flour with hard white wheat flour on the quality of yellow alkaline noodles

Yellow alkaline noodles (YAN) were prepared from durum and hard white wheat flour blends and evaluated for noodle color, appearance and cooked noodle texture. Raw noodle brightness, L^∗, and yellowness, b^∗, improved significantly with durum flour addition while significant increases in a^∗ values were observed at both 2 h and 24 h. The very low noodle speck count of white wheat noodles remained constant over the 24 h period at any durum flour addition. Noodle bite, MCS, decreased with the addition of durum flour, resistance to compression (RTC) remained equivalent to the hard white flour control while an associated improvement in cooked noodle recovery (REC) was observed. The study indicates that addition of durum flour at even the 25% level, offers a viable product with improved colour characteristics, consistent RTC and improved REC textural attributes. Uniaxial stress relaxation parameters of cooked noodles significantly correlated with the empirical texture measurements.     

Effect of low voltage electrical stimulation on biochemical and quality characteristics of Longissimus thoracis muscle from one-humped Camel (Camelus dromedaries)

The effects of electrical stimulation (90 V) 20 min post mortem on meat quality and muscle fibre types of four age group camels (1–3, 4–6, 7–9, 10–12 years) camels were assessed. Quality of the Longissimus thoracis at 1 and 7 days post mortem ageing was evaluated using shear force, pH, sarcomere length, myofibrillar fragmentation index, expressed juice, cooking loss and L^∗, a^∗, b^∗ colour values. Age of camel and electrical stimulation had a significant effect on meat quality of L. thoracis. Electrical stimulation resulted in a significantly (P < 0.05) more rapid pH fall in muscle during the first 24 h after slaughter. Muscles from electrically-stimulated carcasses had significantly (P < 0.05) lower pH values, longer sarcomeres, lower shear force value, higher expressed juice and myofibrillar fragmentation index than those from non-stimulated ones. Electrically-stimulated meat was significantly (P < 0.05) lighter in colour than non-stimulated based on L^∗ value. Muscles of 1–3 year camels had a significantly (P < 0.05) lower shear force value, and pH, but longer sarcomere, and higher myofibrillar fragmentation index, expressed juice, and lightness colour (L^∗) than those of the 10–12 years camels. The proportions of Type I, Type IIA and Type IIB were 25.0, 41.1 and 33.6%, respectively were found in camel meat. Muscle samples from 1–3 year camels had significantly (P < 0.05) higher Type I and lower Type IIB fibres compared to those from 10–12 year camel samples. These results indicated that age and ES had a significant effect on camel meat quality.     

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 ¹H relaxation times T₁ and T₂ in representative ham muscle tissues, due to dehydration and salt uptake. MRI maps of the same ham sections were acquired, allowing T₁ and T₂ 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 T₁ and T₁/T₂ ratio were selected in a model (R² = 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.