Feasibility of NIR interactance hyperspectral imaging for on-line measurement of crude composition in vacuum packed dry-cured ham slices

There is a growing market for packaged slices of dry-cured ham. The heterogeneity of the composition of slices between packages is an important drawback when aiming to offer consumers a product with a known and constant composition which fits individual consumer expectations. The aim of this work was to test the feasibility of NIR interactance imaging for on-line analysis of water, fat and salt and their spatial distribution in dry-cured ham slices. PLSR models for predicting water, fat and salt contents with NIR spectra were developed with a calibration set of samples (n = 82). The models were validated with an external validation set (n = 42). The predictive models were accurate enough for screening purposes. The errors of prediction were 1.34%, 1.36% and 0.71% for water, fat and salt, respectively. The spatial distribution of these components within the slice was also obtained.     

Use of computed tomography to study raw ham properties and predict salt content and distribution during dry-cured ham production

Varying salt content in hams of equal brand is a major challenge for Norwegian dry-cured ham producers. This study was thus undertaken to test existing computed tomography (CT) calibration models for salt on entire hams, regarding predictability of salt content at different processing times including final ham and to study salt distribution during processing of dry-cured ham. Twenty-six hams were scanned by computed tomography (CT) 11 times during dry-curing for this purpose. However, previously established calibration models had to be adjusted as they overestimated salt in dry samples. Prediction of ultimate salt content was more accurate approaching the end of the dry-curing process (RMSEP = 0.351-0.595% salt). Inclusion of remaining weight loss improved the prediction accuracy in un-dried samples by approximately 0.1% NaCl. The prediction errors were sufficiently low to be of practical interest.     

Occurrence of ochratoxin A in raw ham muscle,salami and dry-cured ham from pigs fed with contaminated diet

Pork meat-derived products can contribute to the overall ochratoxin A intake, either by carry-over effect, or by environmental mould population cross-contamination. In order to assess the role of these different contamination routes, a study was carried out with pigs challenged orally with OTA contaminated feed at subchronical level. After slaughtering, thighs and minced meat from control and treated groups were transformed into dry-cured hams and salami, respectively, which were analysed for OTA determination after ripening. From collected data, the carry-over in muscle was generally low, whereas a significant contribution to the OTA contamination in dry-cured hams was due to toxinogenic mould population growing on their surface during ripening. Finally, a survey of different types of dry-cured ham (n = 110), from the Italian market, was performed, showing the occurrence of OTA on the surface portion in 84 out of 110 samples with a median value of 0.53 μg/kg and in the inner core in 32 out of 110 samples with a median value lower than 0.1 μg/kg.     

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).     

Non-destructive prediction of hardening pericarp disorder in intact mangosteen by near infrared transmittance spectroscopy

A non-destructive technique to predict a hardening pericarp disorder in intact mangosteen is proposed by using near infrared (NIR) transmittance spectroscopy in the wavelength range of 660-960 nm. The study found that the spectral features of normal pericarp mangosteen and hardening pericarp mangosteen were different. The averaged spectra and individual spectra of hardening pericarp mangosteen from a calibration set (N = 560) were used to develop classification models, using partial least squares discriminant analysis (PLS-DA). A model based on individual spectra obtained better classification. The overall accuracy of classification for a prediction set (N = 358) was 91%. Out of 179 samples of normal pericarp fruits, 167 were identified correctly, while 159 samples out of 179 samples with hard pericarp were predicted correctly. The results showed that NIR transmittance spectroscopy can be used to predict hard pericarp disorder in intact mangosteen fruit accurately.     

Prediction of water and protein contents and quality classification of Spanish cooked ham using NIR hyperspectral imaging

This study was carried out to investigate the ability of hyperspectral imaging technique in the NIR spectral region of 900–1700 nm for the prediction of water and protein contents in Spanish cooked hams. Multivariate analyses using partial least-squares regression (PLSR) and partial least squares-discriminant analysis (PLS-DA) were applied to the spectral data extracted from the images to develop statistical models for predicting chemical attributes and classify the different qualities. Feature-related wavelengths were identified for protein (930, 971, 1051, 1137, 1165, 1212, 1295, 1400, 1645 and 1682 nm) and water (930, 971, 1084, 1212, 1645 and 1682 nm) and used for regression models with fewer predictors. The PLS-DA model using optimal wavelengths (966, 1061, 1148, 1256, 1373 and 1628 nm) successfully classified the examined hams in different quality categories. The results revealed the potentiality of NIR hyperspectral imaging technique as an objective and non-destructive method for the authentication and classification of cooked hams.     

Ultrasonic assessment of the melting behaviour in fat from Iberian dry-cured hams

The feasibility of using ultrasounds to characterize the melting properties of fat from Iberian dry-cured hams was evaluated. Differential Scanning Calorimetry (DSC) and ultrasonic measurements were used to characterize the fat melting. The ultrasonic velocity in fat decreased with the increase in temperature, showing four different sections (0–4 °C, 4–10 °C, 10–20 °C and 20–24 °C). Ultrasonic velocity was related (R² = 0.99) to the percentage of melted fat (%MEF) showing an increase of 5.4 ms⁻¹ for 1% increase of melted fat (%MEF above 60%). The thermal history did not affect the ultrasonic measurements from 10 to 25 °C and, consequently, this range was the most suitable for classifying Iberian dry-cured products with different genetics and feeding backgrounds. Ultrasonic measurements could be a reliable technique to estimate the %MEF and subsequently the related sensory attributes in Iberian dry-cured ham at 10–25 °C, which is the common temperature range for the consumption of Iberian dry-cured products.     

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.     

Genomic typing of enterococci isolated from bovine mammary glands and environmental sources

Enterococcal isolates (n = 102) from various sources of bovine origin on 1 farm were characterized using pulsed field gel electrophoresis analysis of SmaI restriction patterns. Isolates originated from feed samples (n = 6), bedding samples (n = 15), and bovine quarter-milk samples (n = 81). Isolates collected from milk samples included those from high-somatic cell count cows (n = 42), postpartum milk samples (n = 16), and clinical mastitis samples (n = 23). Species evaluated included Enterococcus faecium (n = 68), Enterococcus casseliflavus (n = 29), and Enterococcus faecalis (n = 5). A total of 20 clusters representing 44 isolates were detected when a similarity cut-off level of 75% was applied to interpret the pulsed field gel electrophoresis results. Fifteen of the clusters contained only isolates from milk samples. Four clusters contained isolates from bedding and milk samples. One cluster contained only isolates from feed samples. Clusters comprised of a single species represented 17 of the 20 total clusters. These results suggest enterococci from bovine origin were genetically diverse, whereas a limited number of isolates from various sources appeared to cluster together.     

Diagnosing intramammary infections: comparison of multiple versus single quarter milk samples for the identification of intramammary infections in lactating dairy cows

The objective was to examine the potential benefits of using different combinations of multiple quarter milk samples compared with a single sample for diagnosing intramammary infections (IMI) in dairy cattle. Data used in the analyses were derived from 7,076 samples from 667 quarters in 176 cows in 8 herds in 4 locations (Minnesota/Wisconsin, n = 4; Prince Edward Island, n = 2; Ontario, n = 1; New York, n = 1). Duplicate quarter milk samples were collected at morning milking for 5 consecutive days. Cows were evenly distributed between early postparturient and mid- to late-lactation cows. All samples were frozen for shipping and storage, thawed once, and cultured in university laboratories using standardized procedures consistent with National Mastitis Council guidelines. The presence of specific pathogens was confirmed and identified using the API identification system (bioMerieux, Marcy l’Etoile, France) in each laboratory. A previously developed gold standard was applied to the first sample from d 1, 3, and 5 to classify infected quarters. The data were analyzed separately for coagulase-negative staphylococci (CNS) and Streptococcus spp. Various combinations of test results from d 2 and 4 were used in the test evaluation. These consisted of single samples (n = 4), 2 sets of duplicate samples (2 samples collected on the same day), 2 sets of consecutive samples (2 samples collected 2 d apart), and 2 sets of triplicate samples (2 samples on the same day and a third sample 2 d apart). Series interpretation of duplicate or consecutive samples (i.e., positive = same pathogen isolated from both samples) resulted in the highest specificity (Sp; CNS Sp = 92.1-98.1%; Streptococcus spp. Sp = 98.7-99.6%), but lowest sensitivity (Se; CNS Se = 41.9-53.3%; Streptococcus spp. Se = 7.7-22.2%). Parallel interpretation of duplicate or consecutive samples (i.e., positive = pathogen isolated from either) resulted in the highest Se (CNS Se = 70.8-80.6%; Streptococcus spp. Se = 31.6-48.1%), but lowest Sp (CNS Sp = 72.0-77.3%; Streptococcus spp. Sp = 89.5-93.3%). The difference in estimates between single and duplicate samples was larger than between single and consecutive samples. Overall, triplicate samples provided the best combination of Se and Sp, but compared with a single sample, provided only a modest gain in Sp and little or no gain in Se.     

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 Influence of Debaryomyces hansenii, Candida deformans and Candida zeylanoides on the aroma formation of dry-cured “lacón”

The volatile profile of dry-cured “lacón” that has been inoculated with three different yeasts were determined and compared with a non-inoculated dry-cured “lacón”. Yeasts (Debaryomyces hansenii, Candida deformans and Candida zeylanoides) that were used as starter cultures in the present study were selected among yeasts that were isolated from native dry-cured “lacón” at different stages of ripening process. These starters were spread on dry-cured “lacón” surface in order to test their capacity to contribute on the generation of volatile compounds. A total of forty two volatile compounds were detected by dynamic headspace sampling followed by gas chromatography–mass spectrometry analysis. Significant differences (P < 0.001) on the volatile profiles of different batches were found in comparison with non-inoculated samples, showing the highest total area values for the inoculated ones. Esters were the most abundant chemical family in all batches studied except for C. zeylanoides batch, which showed greater amount of hydrocarbons than esters. The second more abundant family was hydrocarbons for control and C. deformans batches (147.6 and 445.24 × 10⁶ area units, respectively), alcohols for D. hansenii (363.77 × 10⁶ area units) and esters for C. zeylanoides (248.33 × 10⁶ area units). However, the aldehyde compound group in control batch samples was found to be significantly higher than in the inoculated ones (P < 0.001). Among inoculated batches, D. hansenii batch showed the lowest hexanal content (14.42 × 10⁶ area units) in comparison with non-inoculated batch (105.99 × 10⁶ area units). Among all batches studied, D. hansenii batch presented the highest area values for esters, alcohols, linear hydrocarbons, ketones, acids and furans; control batch for aldehydes and C. zeylanoides batch for branched hydrocarbons. Therefore, the study showed that every yeast strain produced a specific volatile profile which was also different from that of the control dry-cured “lacón”.     

Influence of low-sodium mixtures of salts on the post-salting stage of dry-cured ham process

The reduction of added sodium chloride in dry-cured ham has been proposed to decrease the amount of sodium in the diet. The effect of substituting sodium chloride by potassium chloride, calcium chloride and magnesium chloride in some physicochemical characteristics of dry-cured ham throughout the post-salting stage was evaluated. The partial replacement of NaCl had significant effects on salt content at the end of the post-salting stage in the traditional process and this significantly affected a_w. The results showed that lower sodium hams, salted with a combination of NaCl and KCl, needed a maximum of 16 days more (32% increase) of post-salting than hams salted with 100% NaCl, while hams salted with a combination of NaCl, KCl, CaCl₂ and MgCl₂ needed a maximum of 26 days more (52% increase).     

Detection of adulterants such as sweeteners materials in honey using near-infrared spectroscopy and chemometrics

Near-infrared (NIR) spectroscopy combined with chemometrics methods has been used to detect adulteration of honey samples. The sample set contained 135 spectra of authentic (n = 68) and adulterated (n = 67) honey samples. Spectral data were compressed using wavelet transformation (WT) and principal component analysis (PCA), respectively. In this paper, five classification modeling methods including least square support vector machine (LS-SVM), support vector machine (SVM), back propagation artificial neural network (BP-ANN), linear discriminant analysis (LDA), and K-nearest neighbors (KNN) were adopted to correctly classify pure and adulterated honey samples. WT proved more effective than PCA, as a means for variables selection. Best classification models were achieved with LS-SVM. A total accuracy of 95.1% and the area under the receiver operating characteristic curves (AUC) of 0.952 for test set were obtained by LS-SVM. The results showed that WT-LS-SVM can be as a rapid screening technique for detection of this type of honey adulteration with good accuracy and better generalization.     

Creatine and creatinine evolution during the processing of dry-cured ham

Dry-curing of ham involves many biochemical reactions that depend on the processing conditions. The aim of this study was to evaluate the effect of the dry-cured processing on the concentration of creatine, creatinine and the creatinine/creatine ratio. Dry-cured hams under study were salted using three different salt mixtures (100% NaCl; NaCl and KCl at 50% each; and 55% NaCl, 25% KCl, 15% CaCl₂ and 5% MgCl₂) in order to observe its influence on creatinine formation but no significant differences were found between them at any time of processing. However, significant differences between different post-salting times (20, 50 and 80 days) and the ripened hams (7, 9 and 11 months of ripening) were observed. Results showed that creatine and creatinine remain stable once the ripening period is reached. These results were confirmed when analysing dry-cured ham samples submitted to extreme conditions of temperature and time (20, 30, 40 and 70 °C during 0, 20, 40 and 60 min) as well as commercial dry-cured hams with more than 12 months of processing.     

MRI-based analysis,lipid composition and sensory traits for studying Iberian dry-cured hams from pigs fed with different diets

The present work was aimed to study Iberian dry-cured hams from pigs reared outdoors and either fed with acorns and grass (AG) or with oleic acid enriched concentrates (HO), by means of their fatty acid profile, sensory traits and Magnetic Resonance Imaging (MRI). The level of total saturated fatty acids (SFA) was higher in HO than in AG hams, whereas total monounsaturated (MUFA) and polyunsaturated fatty acids (PUFA) showed higher proportions in AG than in HO Iberian dry-cured hams. Besides, lower levels of the n ? 6/n ? 3 ratio were found in AG than in HO dry-cured hams. Sensory analyses only showed differences between AG and HO Iberian dry-cured hams in pastiness (higher in AG hams, p = 0.039) and marbling (lower in AG hams, p = 0.002). Pig feeding also leads to differences in two computational texture features obtained by MRI-based analysis. Thus, analysis of the fatty acid profile and MRI-based analysis might be used for classifying dry-cured hams from pigs fattened with different diets.     

Optical scattering with hyperspectral imaging to classify longissimus dorsi muscle based on beef tenderness using multivariate modeling

The objective of this study was to develop a non-destructive method for classifying cooked-beef tenderness using hyperspectral imaging of optical scattering on fresh beef muscle tissue. A hyperspectral imaging system (λ = 922–1739 nm) was used to collect hyperspectral scattering images of the longissimus dorsi muscle (n = 472). A modified Lorentzian function was used to fit optical scattering profiles at each wavelength. After removing highly correlated parameters extracted from the Lorentzian function, principal component analysis was performed. Four principal component scores were used in a linear discriminant model to classify beef tenderness. In a validation data set (n = 118 samples), the model was able to successfully classify tough and tender samples with 83.3% and 75.0% accuracies, respectively. Presence of fat flecks did not have a significant effect on beef tenderness classification accuracy. The results demonstrate that hyperspectral imaging of optical scattering is a viable technology for beef tenderness classification.     

Effects of phosphine and methyl bromide fumigation on the volatile flavor profile and sensory quality of dry cured ham

In separate experiments, randomized complete block designs with three replications were utilized to evaluate the effects of phosphine (PH₃) (0, 200 and 1000 ppm for 48 h) and methyl bromide (MB) (0, 4, 8, 16, and 32 mg/L for 48 h) fumigation concentration on the volatile flavor compound concentrations in dry cured ham. Minimal differences existed (P > 0.05) in the presence and concentration of aroma active compounds in both PH₃ and MB fumigated hams but sulfur and oxidation compounds were more prevalent (P < 0.05) in the fumigated treatments when compared to the control. As phosphine fumigation concentration increased, the residual concentration of phosphine also increased in the hams (P < 0.05), but all samples contained levels that are lower than the legal limit of phosphine allowed in stored food products (0.01 ppm) in the United States. A triangle test (n = 56) indicated that consumers could not discriminate (P > 0.75) between the control hams and those that were fumigated with PH₃. Minimal aroma/flavor differences existed among MB, PH3 and control hams, and dry cured ham that was fumigated with PH₃ was safe for consumption based on residual phosphine concentrations in the meat tissue.     

Changes of free amino acids and biogenic amines during extended ageing of Italian dry-cured ham

Sixty-two fresh hams were sub-grouped to undergo different processing times (15, 19 and 23 months), and corresponding dry-cured hams were analysed for changes in moisture, protein, NaCl, pH, proteolysis, free amino acids (FAAs) and biogenic amines (BAs) as related to the extended ageing. Dry-cured hams were influenced by ageing time, showing a decrease in moisture and water activity and an increase in pH, nonprotein nitrogen (NPN) and FAAs in more aged samples. The increase in FAAs and BAs progressively observed until the last sampling time might be enhanced by the moderate salt content (≈5 g NaCl/100 g muscle) and relatively high a_w (>0.90) of dried hams even at 23 months of processing. Among FAAs, arginine did not increase with ageing, which might be due to arginine hydrolysis to ammonia and ornithine, followed by decarboxylation to putrescine, i.e. molecules largely present in the more aged hams. Tyramine, the most abundant among BAs, putrescine and cadaverine showed a dependence on time and proteolysis indices (NPN and FAAs). In this respect, the practice of extending the standard ageing time of typical italian dry-cured ham (13-15 months), regarded as a tool for improving sensory property of this product, should be supported by further studies, mainly at the manufacturing level, to minimize FAA and BA generation.     

Risk factors associated with short-term post-treatment outcomes of clinical mastitis

The objectives of this study were to characterize 60-d outcomes after treatment of mild (abnormal milk) and moderate (abnormal milk and abnormal udder) cases of clinical mastitis (CM) occurring in a single quarter of cows on Wisconsin farms (n = 4) and to determine risk factors associated with those outcomes. Duplicate milk samples were collected from the affected quarter of each cow for microbiological analysis at the onset of CM (PRE) and 21 d later (POST). Cows were treated only in the affected quarter using an intramammary product containing 125 mg of ceftiofur. Bacteriological cure was defined as absence of pathogens in the POST sample obtained from the enrolled quarter. Recurrence was defined for the cow when CM occurred after the milk-withholding period for the enrolled case of CM. Retention in the herd was defined when a cow was retained within the herd for the 60-d follow-up period. Somatic cell count reduction (SCCR) was defined at the cow level as somatic cell count (SCC) below 200,000 cells/mL at the Dairy Herd Improvement Association test day occurring between 21 to 55 d post-treatment. The effects of farm, days in milk, parity, severity, microbiological diagnosis at PRE, previous milk yield, previous SCC, previous occurrence of CM and treatment duration on selected post-treatment outcomes were assessed using Chi-squared analysis and logistic regression. Microbiological results at PRE were distributed as: Escherichia coli (n = 14), Klebsiella spp. (n = 11), Enterobacter spp. (n = 8), Serratia spp. (n = 7), other gram-negative species (n = 3), Streptococcus spp. (n = 25), coagulase-negative staphylococci (n = 4); Staphylococcus aureus (n = 1); Streptococcus agalactiae (n = 1), other gram-positive species (n = 9), and culture negative (n = 60). Treated quarters were more likely to experience bacteriological cure when the cow experienced CM for the first time in the lactation and when no pathogen was recovered from PRE milk samples obtained from the enrolled quarter. Parity and bacteriological cure were associated with the probability of recurrence. Greater milk yield at previous Dairy Herd Improvement test was the most important predictor for retention within the herd. When SCC before CM was >200,000 cells/mL the probability of having SCCR after treatment was decreased. When the case experienced bacteriological cure, the cow was less likely to experience recurrent cases and was more likely to have SCCR below 200,000 cells/mL. Post-treatment outcomes, such as recurrence and SCCR, are strongly associated with bacteriological cure and, when monitored, can be used to help determine if a treatment has been successful. Information about the etiology of CM, history of clinical and subclinical mastitis, and parity are useful to review when making strategic treatment decisions.