Iberian Dry-cured Loins Research Articles

Assessing the Impact of Pomegranate Peel Extract Active Packaging and High Hydrostatic Pressure Processing on Color and Oxidative Stability in Sliced Nitrate/Nitrite-Reduced Iberian Dry-Cured Loins

Our study aimed to assess the impact of active packaging with pomegranate peel extract (0.06 mg gallic acid eq./cm2) and/or high-pressure treatment (600 MPa, 7 min) on the instrumental color, lipid, and protein oxidation of Iberian dry loins formulated with reduced nitrate/nitrite levels (0, 37.5, and 150 mg/kg) during 100-day refrigerated storage (4 °C). CIE L*a*b* coordinates were measured, and malondialdehyde, carbonyls, and free thiol contents served as markers for lipid and protein oxidation. Active packaging lowered CIE L* (35.4 vs. 34.1) and a* (15.5 vs. 14.5) and increased yellowness (15.6 vs. 16.3) and hue (45.2 vs. 48.4), while pressurization increased CIE L* (33.1 vs. 36.3) and diminished a* values (16.1 vs. 13.9). Ongoing nitrate/nitrite amounts significantly influenced lipid peroxidation, protein carbonyl formation, and free thiol loss. Active packaging and high-pressure processing had varying effects on carbonyl and thiol contents. Neither pressurization nor active packaging impacted malondialdehyde formation. Pressurization enhanced the formation of 4-HNE (503 vs. 697 pg/g). Protein oxidation proved more sensitive to changes, with active packaging offering protection against protein carbonylation (15.4 vs. 14.7 nmol carbonyls/mg protein), while pressurization induced thiol loss (34.3 vs. 28.0 nmol Cys eq./mg protein). This comprehensive understanding provides essential insights for the meat industry, emphasizing the necessity for customized processing conditions to enhance color stability, lipid preservation, and protein integrity in dry-cured loin slices.

Influence of high-pressure processing and varying concentrations of curing salts on the color, heme pigments and oxidation of lipids and proteins of Iberian dry-cured loins during refrigerated storage

The effect of high hydrostatic pressure (HHP) on reduced ingoing amounts of both nitrate and nitrite (150, 75, 37.5, and 0 mg/kg of each curing salt) dry-cured loins during the refrigerated storage was studied. Changes in instrumental color, nitrosylmyoglobin (NOMb) and Zinc protoporphyrin (ZnPP) contents, and lipid and protein oxidation were analyzed. The reduction of ingoing amounts of nitrate/nitrite in loins decreased the redness (CIE a*) and NOMb content in the dry-cured products while increased the ZnPP content and the lipid oxidation measured as TBA-RS. In contrast, the diminution of ingoing curing agents up to 37.5 mg/kg NO3−/NO2− did not significantly affect color, lipid, and protein oxidation over refrigerated storage. In comparison to control samples, HHP increased lightness (CIE L*) and the extent of lipid oxidation, meanwhile reduced protein carbonyl and thiol contents over storage. Neither NOMb nor ZnPP contents were affected by HHP treatment over storage time. Therefore, the reduction of ingoing amounts up to 37.5 ppm NOx together with a pressurization treatment at 600 MPa 7 min controlled lipid and protein oxidation.

Sensory Characterization of Iberian Dry-Cured Loins by Using Check-All-That-Apply (CATA) Analysis and Multiple-Intake Temporal Dominance of Sensations (TDS).

The aim of the present work was to sensorially characterize different commercial categories of Iberian dry-cured loins (varying genetic and feeding background) using a novel dynamic sensory technique, and to explore consumers preferences applying a rapid method. The samples (green label—GL, Cebo de Campo Ibérico; red label—RL, Bellota 50% Ibérico; and black label—BL, Bellota 100%) were analyzed by (i) Check-all-that-apply (CATA) with the evaluation of an ‘Ideal’ dry-cured loin and the overall liking, and by (ii) multiple-intake Temporal Dominance of Sensations (TDS). The CATA results indicated that the sensory characteristics of RL samples were closer to those of the ‘Ideal’ loin. Furthermore, juiciness, marbling, cured flavor, chewiness, persistence, and brightness were selected as ‘must-have’ attributes. Juiciness cured flavor and red color were considered as drivers of liking. TDS results showed that flavor attributes presented the highest dominance rates, with saltiness being the most dominant attribute along BL sample evaluation, and with cured and paprika flavor for GL and RL samples. These sensory technique results displayed the ability to sensorily characterize dry-cured loins, providing different, complementary, and valuable information.

Near infrared spectroscopy (NIRS) as tool for classification into official commercial categories and shelf-life storage times of pre-sliced modified atmosphere packaged Iberian dry-cured loin

The potential of Near Infrared Spectroscopy combining different spectral treatments and classification models was assessed for the classification of individual pre-sliced Iberian dry-cured loin packaged under modified atmosphere packaging (MAP) into three official commercial categories (which involve the breed purity and production system) according to the current Iberian Quality Standard (Black, Red and White) and for the assignment to the shelf-life time (0, 4, 8 and 12 months). External validation results provided acceptable results, with up to 100% of samples correctly assigned to Black and White official commercial category and into all storage times. Actually the 100% assignments were obtained using more than one approach (SIMCA and LDA for commercial categories and PLS-DA, SIMCA and LDA for storage times).These results might contribute to support the on-line control of authenticity of official commercial category and to facilitate the monitoring of the quality of pre-package dry-cured products throughout the shelf-life prediction.

Quality Traits of Dry-Cured Loins from Iberian Pigs Reared in Montanera System as Affected by Pre-Freezing Cure.

Iberian dry-cured loins from pigs fattened in Montanera are usually subjected to seasonal production, which could be overcome through freezing the loin before the curing process. Hence, three homogeneous batches (n = 15 per batch) were established to evaluate the effect of different pre-freezing cure (−20 ± 2 °C) times (three and six months) of raw material on main quality characteristics of dry-cured loins in comparison to those elaborated from unfrozen meat. All samples were subjected to similar seasoning and same curing length to obtain dry-cured loins. Results showed a decrease in lightness, redness, chrome and hue values, polyunsaturated fatty acids (PUFA), higher oxidative phenomena, and changes in rheological properties in fresh loins on account on freezing (p ≤ 0.05). Some quality parameters of dry-cured loins were affected by freezing, weight loss, and hardness being higher as well as salt content being lower. PUFA and Warner–Braztler Shear Force (p ≤ 0.05) also showed higher values in dry-cured loins from frozen meat than those elaborated from unfrozen counterparts.

Reduction of nitrate and nitrite in Iberian dry cured loins and its effects during drying process

Four batches of Iberian dry-cured loins were manufactured with reduced ingoing amounts of both nitrate and nitrite: 150 mg/kg, 75 mg/kg, 37.5 mg/kg and 0 mg/kg. The effect of reducing or removing nitrate and nitrite and time of drying on physicochemical parameters (moisture, pH, water activity, chloride and residual nitrate and nitrite contents), instrumental colour and nitrosylmyoglobin content, lipid and protein oxidation and on microbiological counts (L. monocytogenes, aerobic mesophilic bacteria and moulds and yeast counts) were investigated. Lipid oxidation increased during the drying process being higher for non-added NO3−/NO2−, meanwhile protein oxidation affected also those with 37.5 and 75 mg/kg of NO3−/NO2− added. The removal of these additives affected instrumental colour coordinates and total colour changes showing that the variation of coloration would be perceptible by the consumer. Nitrosylmyoglobin content was significantly higher for NO3−/NO2− added loins. Reduced levels of these additives up to 37.5 mg/kg did not show significant effects on their physico-chemical, microbiological and colour.

Immune-spaying as an alternative to surgical spaying in Iberian × Duroc females: Effect on quality characteristics and fatty acid profile in dry-cured shoulders and loins

The aim of this study was to assess the effect of immune-spaying on meat quality characteristics and fatty acid profile of dry-cured shoulders and loins by comparing Iberian×Duroc surgically spayed females, immune-spayed females and entire females. There were no significant differences on the physicochemical composition of dry-cured shoulders; however the intramuscular fat content of dry-cured loins was higher in immune-spayed females than entire ones, but not significantly different from spayed females. Immune-spayed females showed the highest values, which could improve the sensory quality of Iberian dry-cured loins, since it is considered an index of high quality. On the other hand, the PUFA content of both dry-cured shoulders and loins proved to be lower in immune-spayed than spayed females, which could prevent excessive fat oxidation responsible for rancidity. Therefore, immune-spaying could be a viable alternative to surgical spaying from the meat quality point of view.

A Statistical Agreement-Based Approach for Difference Testing

A statistical approach based on measures of agreement is proposed for use in a sensory analysis context. This approach considers the idea of using statistical agreement to provide information on the homogeneity of the raters' responses, so that this information can then be used to discriminate between products. It can also be used to measure the expertise level of raters. Although the prime focus is on difference testing by the triangle test (ISO 4120:2008), the proposed methodology can also be applied in other contexts such as the paired comparison test (ISO 5495:2009) or the duo-trio test (ISO 10399:2010), among others. The proposed approach is not a substitute for binomial statistical analysis, but rather it can be used as a complement. It is especially useful when few panelists are available and replications are needed. An experiment that evaluates two types of Iberian dry-cured pork loins through the triangle test is performed to illustrate the applicability of the proposed approach. Practical Applications The proposed methodology is very helpful for users of sensory analysis techniques, and especially for those focused on differentiation tests. It can complement the classical methodologies on this topic. It is especially useful when there are few raters and replications must be performed. It can also be applied to evaluate the accuracy of panelists being trained by an expert.

Analysis of volatile molecules in Iberian dry-cured loins as affected by genetic, feeding systems and ingredients

Volatile molecules of unseasoned dry-cured loins (DCL) produced from pigs with different genetic [IB = pure Iberian, IBxD = (♀) Iberian × (♂) Duroc (50%) and DxIB = (♀) Duroc × (♂) Iberian (50%)] and feeding systems (MON = outdoors in “montanera” system, HOVE = indoors with mixed diet enriched in oleic acid and supplemented with α-tocopherol and CON = indoors with conventional mixed diet) were investigated using SPME coupled to gas chromatography/mass spectrometry (GC/MS). According to the overall volatiles profile of DCL, lipid oxidation and Maillard-type reactions were the main routes for volatiles generation although the contribution of mould and yeast from loin’s surface should be considered. Aliphatic hydrocarbons were the major chemical family in most DCL batches while alcohols were the chemical family with the largest variety of volatile compounds. Genetic had a slight effect, with crossbreed type (IBxD vs. DxIB) being the most influential factor. Certain compounds derived from grass consumption (decane, p-xilene and three terpenes compounds) had higher chromatographic areas in IB-MON than in IB-HOVE DCL, suggesting their role as indicators of the outdoor “montanera” feeding system. Changes in the volatiles profile of DCL caused by the lack of seasoning were also described.

Decolouration and lipid oxidation changes of vacuum-packed Iberian dry-cured loin treated with E-beam irradiation (5 kGy and 10 kGy) during refrigerated storage

Abstract The effect of irradiation (0, 5 and 10 kGy) on the oxidative and colour stability of vacuum-packed Iberian dry-cured loin slices from pigs fed on concentrate feed (CON) or free-range reared (FRG) stored under refrigerated storage was studied. Irradiation treatment increased lipid oxidation, measured as TBA-RS values and hexanal content of dry-cured loins. It also increased redness (CIE a⁎) and lightness (CIE L⁎) of dry-cured loins. Refrigerated storage reduced the differences due to irradiation treatment of instrumental colour values like lightness. However, the decrease of redness during storage was more marked in irradiated than in non-irradiated dry-cured loin. Storage increased differences in TBA-RS values between irradiated and non-irradiated FRG dry-cured loin, while the opposite trend was found for CON dry-cured loins. In addition, no differences in the hexanal content were found after 30 days of refrigerated storage. Therefore, the storage of Iberian dry-cured loin in absence of oxygen by using a vacuum packaging could be an adequate method to reduce changes associated to irradiation treatment in Iberian dry-cured loin. Industrial relevance Iberian dry-cured loin is a high sensory quality meat product with increasing projection in external markets Irradiation has shown to be an effective method to control pathogen and spoilage microorganisms in meat and meat products. However, e-beam irradiation can promote colour and oxidation changes that could modify their sensory characteristics. The study aimed the evaluation of e-beam irradiation at two levels (5 and 10 kGy) — higher doses than those that could be necessary to control pathogen microorganisms in this kind of product — on colour changes and lipid oxidation at vacuum-packed slices of Iberian dry-cured loin during subsequent extended chilled storage. E-beam treatment induced changes in colour and lipid oxidation in sliced Iberian dry-cured loin immediately after treatment and subsequent refrigerated storage.

Analysis of volatile compounds of Iberian dry-cured loins with different intramuscular fat contents using SPME–DED

In order to study the effect of both, ripening time and IMF content on the volatile profile of Iberian dry-cured loin, volatile compounds from the headspace of 10 Iberian dry-cured loins with different intramuscular fat contents (IMF), low (average IMF content of 2.3%) and high (average IMF content of 6.7%), at days 40 and 55 of the ripening process were analysed using SPME coupled to a direct extraction device (DED) and subsequent gas chromatography/mass spectrometry (GC/MS). Chromatographic areas of the main chemical families detected (hydrocarbons, aldehydes, alcohols, ketones and acids) increased with ripening time. A higher total chromatographic area was detected in the headspace of high IMF loins compared to low IMF ones. Several volatile compounds derived from lipid oxidative reactions, such as hexanol, octanal, ( E, E)-2,4-heptadienal or ( E)-2-decenal, and others from the degradation of certain amino acids, such as dimethylsulfide, 3-methylbutanal or phenylacetaldehyde, showed higher chromatographic areas in the headspace of high IMF loins than in low IMF ones. Thus, IMF content could influence both the generation of volatile compounds and the transfer of such compounds from the product matrix to the headspace.

Preference and juiciness of Iberian dry-cured loin as affected by intramuscular fat content, crossbreeding and rearing system

Preference ranking tests for juiciness and overall liking of dry cured loins from Iberian pigs with different genetic backgrounds (pure Iberian or crossbred Iberian × Duroc pigs), reared under different productive systems (outdoors on acorns and grass or indoors with mixed diets) and with different intramuscular fat (IMF) content, were conducted. IMF showed a positive influence on preference for juiciness and liking in subjects over 25 years of age, while younger consumers showed a similar trend for juiciness but not for preference. Loins from pure Iberian pigs showed significantly better ranking for juiciness and overall liking than those from crossbred pigs, even when the IMF content was similar. Dry cured loins from pigs reared outdoors and fed on acorns and pasture were ranked significantly better than those from animals fed indoors on concentrates, even though the mixed diets used were enriched in monounsaturated fatty acids and vitamin E in order to obtain meat with similar features to that of pigs reared outdoors, and despite very similar IMF contents. In conclusion, dry cured loins with high IMF content, from pure Iberian pigs and reared outdoors on acorns and grass attain the highest consumer preference.

Lipolytic and oxidative changes in Iberian dry-cured loin

This study was conducted using 61 Iberian pigs from four different genetic lines fattened under two different rearing systems. Fatty acid composition of neutral lipids (NL), polar lipids (PL) and free fatty acids (FFA) of the 61 fresh loins and their corresponding dry-cured loins and indices of lipid oxidation (hexanal, TBARS and rancid flavour) of the dry-cured loins were analyzed. Although the total amount of fatty acids from PL decreased most (89.77%), the fatty acid profile of FFA from dry-cured loin was more similar to that of NL from fresh loins. Monounsaturated fatty acids (MUFA) were the most abundant FFA type (260 mg/100 g muscle dry matter) followed by saturated fatty acid (SFA) (256 mg/100 g muscle dry matter) and polyunsaturated fatty acids (PUFA) (148 mg/100 g muscle dry matter). Neither genetic line nor rearing system showed any significant ( P > 0.05) effect on the decrease of fatty acids in the lipid fractions studied. The important decrease in PUFA from NL (43.70%) and PL (89%) was not reflected in higher oxidative indices in dry-cured loin. Neither PCA nor Pearson’s correlation showed any clear relationships between lipolytic changes and oxidative indices.

Sensory characteristics of Iberian dry-cured loins: Influence of crossbreeding and rearing system

The sensory characteristics of Iberian dry-cured loins and the influence of crossbreeding (pure Iberian – IB, Iberian female × Duroc male – IB×D and Duroc female × Iberian male – D×IB) and rearing system (outdoors fed on acorns and pasture – MON, indoors fed on concentrates high in oleic acid sunflower oil and supplemented with 250 mg/kg of α-tocopherol acetate -HOVE- and indoors fed on control concentrates – CON) on sensory attributes were studied. Dry-cured loins from IB-MON and IB-HOVE pigs, which showed the highest intramuscular fat (IMF) content ( p < 0.01), reached higher scores for brightness, marbling traits (intensity, size and shape) and juiciness, and lower for hardness, dryness and fibrousness than loins from crossbred pigs (IB×D-HOVE, IB×D-CON and D×IB-HOVE). In fact, IMF content was positively linked to juiciness and marbling attributes and negatively to dryness, hardness and fibrousness, which was also observed in the principal component analysis (PCA). Neither the crossbreeding nor the rearing system seemed to influence odour, flavour and taste features. The PCA evidenced that dry-cured loins from IB-MON and IB-HOVE batches gathered together and were placed near to marbling attributes, juiciness and IMF content.

Colour and lipid oxidation changes in dry-cured loins from free-range reared and intensively reared pigs as affected by ionizing radiation dose level

The effect of irradiation (0, 5 and 10 kGy) of vacuum-packaged Iberian dry-cured loin slices from pigs fed on concentrate (CON) or free-range reared (FRG) was studied in relation to colour changes, TBA-RS and hexanal content. Both, ionizing radiation and type of loin had a significant effect on the instrumental colour parameters of the samples. Irradiation resulted in significantly higher a*-values in both sets of loins, indicating a redder colour. Numerically calculated total colour difference (Δ E) changes were significantly less intense in CON vacuum-packaged dry-cured loin slices than in FRG samples and changed significantly at 10 kGy dose levels in both types of samples. TBA-RS numbers were significantly affected by irradiation dose and type of loin and increased linearly with dose in both types of slices. Increments in TBA-RS numbers in FRG loin slices was dose-dependent and was closely related to the type of dry-cured loin. Irradiation of dry-cured loin slices significantly increased hexanal contents in both groups of loins and the increases were dose-dependent and greater in FRG samples than in CON samples. Differences in the characteristics of the raw material and initial lipid oxidation level could play an important role in the irradiation-induced changes in vacuum-packaged dry-cured loin slices.

Volatile compounds on the surface and within Iberian dry-cured loin

The profile of volatile compounds from external and internal areas of Iberian dry-cured loin was studied by headspace solid-phase microextraction. Higher levels of 16 volatile compounds (hexane, decane, 3-methylbutanal, several sulphur compounds and some aromatic hydrocarbons) were detected in the outer part of the loins. These differences could be owing to several factors, such as greater exposure to oxygen and dehydration conditions in the surface of the product, which favour oxidation reactions and Strecker degradation of amino acids. Moreover, the addition of spices on the surface and the proximity of a mould layer growing on the surface of the product could also contribute to the higher levels of these compounds on the external layer. However, other sulphur compounds coming from spices showed similar levels on the surface and within the loins. This different behaviour could be a consequence of different diffusion rates depending on the features of the compound and the matrix.

Volatile compounds in Iberian dry-cured loin

The volatile profile of Iberian dry-cured loin from four different Iberian pig lines (Entrepelado, Lampiño, Retinto and Torbiscal) and two feeding systems (OUT – fed on acorn and grass-vs.-IND – fed on high oleic acid concentrate) was studied using solid phase microextraction (SPME). 133 volatile compounds were identified and assigned to 16 chemical families. Alcohols were the major group, ethanol being the main compound. The high number of esters detected and the levels of ethanol and acetic acid found, points to an important role of microorganism activity in the formation of volatile compounds in Iberian dry-cured loin. Sulphur compounds, coming mostly from garlic, constituted an important group, with 14 compounds. Significant differences were found among loins from pigs reared in different feeding systems but not among Iberian pig lines. Dry-cured loins from OUT pigs showed higher levels of many compounds derived from lipid oxidation, such as octanoic acid ( P=0.000), decanoic acid ( P=0.018) or hexanal ( P=0.014).