Effects of breeds on the formation of heterocyclic aromatic amines in smoked lamb

Heterocyclic aromatic amines (HAAs) are mutagenic and carcinogenic compounds, which are commonly detectable in cooked meat products. The objective of this study was to evaluate the effect of sheep breeds on the formation of HAAs in smoking cooked lamb. The results showed that HAAs in smoked lamb meat products were generally low (2.74–5.42 ng g^?1), with most being Harman and Norharman. IQ, MeIQx, 4,8‐DiMeIQx, Trp‐p‐2, PhIP and MeAaC were not detected in smoked lamb meat products in the present study. The total content of HAAs differed between meat products of different sheep breeds, but no difference in the order of magnitude was determined. Smoking altered the content of protein, fat, moisture and free amino acids in lamb meat products, which was probably mostly contributed by the reduction in meat moisture. Free tryptophan decreased in all breeds after smoking, which was probably used to synthesise HAAs. In summary, HAAs were low in smoked lamb meat products of all sheep breeds; thus, consumption of smoked lamb meat products should contribute very limited intake of HAAs.     

Dietary administration of ewe diets with a distillate from rosemary leaves (Rosmarinus officinalis L.): Influence on lamb meat quality

The effect of including distilled rosemary leaf in the diet of pregnant ewes on subsequent lamb meat quality was studied. Thirty-six Segureña ewes were randomly assigned to three homogeneous groups. One group was fed a basal diet (BD) as control while the diet of the other two groups was modified by substituting 10% (R₁) and 20% (R₂) of the BD with a pellet made from 50% barley and 50% of distilled rosemary leaves (DRL). Meat spoilage (TVC, PSY and MYC), TBARS, CIELab coordinates and the sensory characteristics contribution of fresh lamb meat packed in MAP (70% O₂:30% CO₂) were analyzed on days 0, 7, 14 and 21. In general, R₁ and R₂ had higher a^* values, better scores for meat and fat colour (P < 0.05) and lower TBARS and rancid odour (P < 0.05), than the control samples. The total viable count was lower in meat DRL. No statistically significant differences were detected between the two treatments (10–20% DRL).     

Southern Spain lamb types discrimination by using visible spectroscopy and basic physicochemical traits

The potential for using visible spectroscopy (400–700 nm) to classify six types (breed × production system) of lamb meat was investigated. Seven wavelengths namely 400, 410, 420, 450, 510, 610 and 670 nm were retained for the discriminant analysis. The basic meat physicochemical traits of Longissimus dorsi were also studied and a model including that information together with the spectra was developed to compare both accuracies. Then, Myoglobin content, water holding capacity, pH, a^*, 670 and 610 nm wavelengths, protein percentage, L^*, ash content, 450 and 420 nm wavelengths and moisture percentage were selected as variables for the development of the discriminant function. The data analysis showed that it was possible to discriminate the lamb types with accuracy around 83% using visible spectroscopy. However these results improved to 95% when using the reflectance together with basic physicochemical traits (12% better than using only the spectra).     

Quantitation of Lamb Content in Mixtures with Raw Minced Beef Using Visible, Near and Mid-Infrared Spectroscopy

Samples of beef (32), lamb (33) and 5%, 10% and 20% (w/w) lamb-in-beef mixtures (33 each) were minced and reflectance scanned in the visible, near and mid-infrared spectral regions. Partial least squares (PLS) regression models were developed to predict percentage lamb content using each spectral region alone and combinations of all three. The most accurate models combined mid-IR (800-2000 cm^-1) and near IR (1100-2498 nm) spectral data following 2^nd derivatization; standard errors of prediction of 0.91% (0–20% range in lamb content) and 4.1% (0–100% range in lamb) were obtained. This technique may be useful for screening such meat mixtures.     

Shelf life extension of ground meat stored at 4 °C using chitosan and an oxygen absorber

The combined effect of chitosan (1%) and an oxygen absorber on shelf life extension of fresh ground meat stored at 4 °C was investigated. Parameters monitored over a 10‐day storage period were Total Viable Count (TVC), Pseudomonas spp., Brochothrix thermosphacta, lactic acid bacteria, Enterobacteriaceae, pH, thiobarbituric acid (TBA), colour, odour and taste. Microbial populations were reduced by 0.4–2.0 log CFU g^?1 for a given sampling day using either chitosan or the oxygen absorber, with the more pronounced effect being achieved by the combination of two. Thiobarbituric acid values for all samples increased during storage with the exception of samples treated with both chitosan and the oxygen absorber in which Thiobarbituric acid values decreased. Changes in pH values with time/different treatments were statistically insignificant. Colour parameters were affected by most treatments. On the basis of microbiological and sensory evaluation, a shelf life extension of 5–6 days was obtained for samples treated with the chitosan and the oxygen absorber combination.     

Microbial profiles of frozen trimmings and silver sides prepared at Indian buffalo meat packing plants

To assess microbiological quality of buffalo meat trimmings (TT = 114) and silver sides (SS = 41), samples were collected from four different Indian meat packing plants. The aim of this study was: (i) to evaluate standard plate count (SPC), psychrotrophic count (PTC), Enterococcus feacalis count (EFC), Staphylococcus aureus count (SAC) and Escherichia coli count (ECC) and the presence of Salmonella spp. and Listeria monocytogenes; and (ii) also to determine vero toxic E. coli (VTEC) by polymerase chain reaction (PCR). TT samples had significantly higher (P < 0.001) SPC, PTC, EFC, and SAC than SS, while across the meat types there was no difference (P > 0.05) in ECC. E. coli was recovered from 32.4% TT and 19.5% SS samples. The prevalence rate of Salmonella spp. and L. monocytogenes in TT was 1.75% and 0.87%, respectively. But no SS sample was found to be positive for any of these two pathogens. VTEC was found in 2.58% of all the tested samples. This finding suggests that TT contain higher microbes but only small numbers of pathogens of latent zoonotic importance. The present study confirmed the importance of maintaining good process hygiene at meat plants for microbiological status of buffalo meat.     

Shelf life extension of lamb meat using thyme or oregano essential oils and modified atmosphere packaging

The effect of thyme (TEO) and oregano (OEO) essential oils as well as modified atmosphere packaging (MAP) in extending the shelf life of fresh lamb meat stored at 4 °C was investigated. In a preliminary experiment TEO and OEO were used at concentrations 0.1 and 0.3% v/w while MAP tested included MAP1 (60% CO(2)/40% N(2)) and MAP2 (80% CO(2)/20% N(2)). Microbiological, physicochemical and sensory properties of lamb meat were monitored over a 20 day period. Sensory analysis showed that at the higher concentration both essential oils gave a strong objectionable odour and taste and were not further used. Of the two essential oils TEO was more effective as was MAP2 over MAP1 for lamb meat preservation. In a second experiment the combined effect of TEO (0.1%) and MAP2 (80/20) on shelf life extension of lamb meat was evaluated over a 25 day storage period. Microbial populations were reduced up to 2.8 log cfu/g on day 9 of storage with the most pronounced effect being achieved by the combination MAP2 plus TEO (0.1%). TBA values varied for all treatments and remained lower than 4 mg MDA/kg throughout storage. pH values varied between 6.4 and 6.0 during storage. Color parameters (L and b) increased with storage time while parameter (a) remained unaffected. Based primarily on sensory analysis (odour) but also on microbiological data, shelf life of lamb meat was 7 days for air packaged samples, 9-10 days for samples containing 0.1% of TEO and 21-22 days for MAP packaged samples containing 0.1% TEO.     

Physicochemical and microbiological changes of “Souvlaki” – A Greek delicacy lamb meat product: Evaluation of shelf-life using microbial,colour and lipid oxidation parameters

Fresh Souvlaki-type lamb meat was packaged under vacuum (VP) and modified atmospheres (MAs) and stored under refrigeration (4 °C) for a period of 13 days. The following gas mixtures were used: M1: 30%/70% (CO₂/N₂) and M2: 70%/30% (CO₂/N₂). Identical samples were aerobically-packaged and used as control samples. Quality evaluation of product stored under the above packaging conditions was conducted using physicochemical and microbiological analyses. Of the chemical parameters determined, pH values of product showed no significant differences for all packaging treatments as a function of storage time. Lipid oxidation of lamb meat was enhanced by aerobic storage and gas mixture M1, whereas VP and gas mixture M2 controlled lipid oxidation to a greater extent. Souvlaki colour stability (as determined by a^∗, b^∗ and L^∗ values) was not negatively affected by either VP or MA conditions during the 13 days of storage. Of the two MAs and VP used, gas mixture M2 and VP were the most effective treatments for the inhibition of total viable counts (TVC), Pseudomonas spp., yeasts and Brochothrix thermosphacta in Souvlaki meat. Lactic acid bacteria (LAB) and Enterobacteriaceae were also found in the microbial flora of Souvlaki and increased during storage under all packaging conditions used. Based on microbiological analysis data and on the proposed a^∗ values, the use of VP and MAP (M2: 70%CO₂/30N₂) extended the shelf-life of “Souvlaki” meat stored at 4 °C by approximately 4–5 days compared to aerobic packaging.     

Microbiological, Chemical, and Physical Changes in Fresh, Vacuum-Packaged Pork Treated with Organic Acids and Salts

The effects of selected organic acids and salts on microbial numbers, pH, exudate, and color were studied for vacuum-packaged, fresh pork chops. Pork chops were dipped for 2 min in (v/v) 1% acetic acid, 1% acetic/1% lactic acid, 1.5% acetic/1.5% sodium acetate, 3% acetic/3% sodium ascorbate, 3% acetic/2% NaCl or sterile, distilled water before being vacuum-packaged and stored at 2°– 4°C for 6 weeks. Treatments containing 3% acetic acid resulted in lower aerobic microbial numbers (P < 0.05) and effectively inhibited Enterobacteriaceae. Treatments containing 1% acetic acid, with or without 1% lactic acid, were ineffective. All acid treatments increased exudate and were detrimental to meat color (P < 0.05) although sodium ascorbate reduced color damage. Chops treated with 3% acetic acid/3% sodium ascorbate had the highest Hunter a and L color scores.     

Microbiological and physicochemical properties of dry‐cured neck inoculated with probiotic of Bifidobacterium animalis ssp. lactis BB‐12

The effect of inoculum level of Bifidobacterium animalis ssp. lactis BB‐12 probiotic strain and ripening period on the quality of dry‐cured neck was studied. The microbiological parameters (Enterobacteriaceae, LAB and TVC) and physicochemical attributes (pH value, a_w, TBARS index, colour) were determined directly after fermentation at 15 °C for 3 weeks, after 6 and 12 months of ripening at 4 °C. The highest LAB count and a lower pH value were found in the meat inoculated with probiotic strain at 6.6 log cfu g^?1 (B2) followed by inoculation with probiotic strain at 6.3 log cfu g^?1 (B1). Level of inoculation had not had an influence on water activity, TBARS index and total colour parameters. Changes of fat oxidation during half‐year of ripening were limited in probiotic meat samples compared to naturally fermented control meat (C). Based on the results, it can be concluded that the most favourable physicochemical and microbiological parameters of the dry‐cured neck were obtained after 6 months of ripening. At that time, the Bifidobacterium BB‐12 at both levels is a good potential starter for meat fermentation.     

Production of a high‐protein meal and fermentable sugars from defatted soybean meal,a co‐product of the soybean oil industry

The goal of this research was to produce a high‐protein meal by treating defatted soybean meal, a by‐product of soybean oil production, with dilute acid. Treatments were a mild hydrolysis at 80 °C with sulphuric acid at concentrations ranging from 0.5% to 2.0% (w/v) and times varying from 1 to 16 h that were arranged according to a central composite rotatable experimental design. The end products were an enhanced‐protein meal and a carbohydrate concentrate of fermentable and nonfermentable sugars. The highest protein content rise, from 48% to 58%, was for treatments with concentrations of acid ranging between 1.2% and 1.7% and times between 1.0 and 2.6 h. The maximum yield of fermentable sugar was 21.0% d.b. at 2.0% H₂SO₄ and treatments of at least 6 h. The conditions that provide a highest protein and sugar contents were the treatments with concentrations of sulphuric acid ranging from 0.9 to 1.9% H₂SO₄ for 1–4 h.     

Southern Spain lamb types discrimination by using visible spectroscopy and basic physicochemical traits

The potential for using visible spectroscopy (400–700 nm) to classify six types (breed × production system) of lamb meat was investigated. Seven wavelengths namely 400, 410, 420, 450, 510, 610 and 670 nm were retained for the discriminant analysis. The basic meat physicochemical traits of Longissimus dorsi were also studied and a model including that information together with the spectra was developed to compare both accuracies. Then, Myoglobin content, water holding capacity, pH, a¹, 670 and 610 nm wavelengths, protein percentage, L¹, ash content, 450 and 420 nm wavelengths and moisture percentage were selected as variables for the development of the discriminant function. The data analysis showed that it was possible to discriminate the lamb types with accuracy around 83% using visible spectroscopy. However these results improved to 95% when using the reflectance together with basic physicochemical traits (12% better than using only the spectra).     

On-Site NIR Spectroscopy to Control the Shelf Life of Pork Meat

Control of meat shelf-life includes the time that it remains in the exhibitor of sale (such as the supermarket) until its rejection for the consumer, or withdrawal due to expiry date. Near infrared spectroscopy (NIRS) is one of the most promising techniques for large-scale meat quality control. This study investigated the potential of on-site NIRS portable instrumentation-based models to predict three microbiological parameters to establish if pork meat is acceptable or not for consumption (aerobic Mesophilous microorganisms, Enterobacteriaceae, and lactic acid bacteria) and pH to quality control food preservation and shelf-life extension on intact slices of pork meat packaged under two different modified atmospheres. NIR calibrations were developed by using an on-site Phazir instrument (Polychromix, Wilmington, MA, USA) in the range 1,600–2,400 nm. A total of 252 samples of pork meat slices were directly scanned twice in reflectance mode on trays, once before and another one after removing the film cover at 1, 3, 5, 7, 9, 12, and 15 days of storage. Results showed that spectra of meat acceptable or not for consumption have marked differences around 1,660 nm. NIRS quantitative prediction models showed r ² values between 0.19 and 0.65 for the microbiological parameters assayed. The developed NIRS methodology makes possible on-site prediction of microbiological status of pork meat with a standard error of cross-validation around 1 log cfu/g. Results have shown that modified atmosphere packaging has no influence on calibration statistics.     

Effect of dietary supplementation with vitamin E on characteristics of vacuum‐packed lamb

The effect of dietary vitamin E supplementation on lamb during vacuum‐packed storage was studied. Thirty‐six weaned male Manchego breed lambs were offered four dietary treatments (20, 270, 520 and 1020 mg vitamin E kg^?1 feed). Lambs were fed the vitamin E‐supplemented diet from 13 until 26 kg live weight. Pieces of M. longissimus dorsi were stored under vacuum at 2 ± 1 °C in the dark and meat quality was assessed after 5, 14 and 28 days of storage. Dietary supplementation significantly increased the α‐tocopherol concentration in the muscle (P < 0.001). Initially, lipid oxidation, meat colour and bacterial load were similar in all groups. In meat of non‐supplemented lambs the thiobarbituric acid reactive substance value increased throughout storage, whereas in meat of supplemented lambs it did not increase. Meat pigments and discolouration proportion were significantly affected by storage time (P < 0.001). The bacterial load was low initially, but after 28 days of storage it was close to 7 log₁₀ colony‐forming units (cfu) cm^?2 and Enterobacteriaceae surpassed the limit of acceptability of 2.5 log₁₀ cfu cm^?2, making the lamb unsuitable for human consumption. Meat of supplemented lambs displayed less lipid oxidation than that of their non‐supplemented counterparts, while meat colour and bacterial load were not affected by supplementation. Copyright © 2007 Society of Chemical Industry     

Partial replacement of sodium chloride with potassium chloride in marinated rabbit meat

This study was aimed at evaluating the consequences of sodium chloride reduction by potassium chloride up to 50% on technological, sensorial and microbiological traits of marinated rabbit meat. In total, 226 rabbit loin meat samples were obtained and subjected to vacuum tumbling using solutions with different NaCl/KCl ratios. Replacing of sodium chloride up to 30% by potassium chloride did not change microbiological traits (total aerobic mesophilic and lactic acid bacteria maximum cell loads), sensorial acceptability (perceived saltiness and overall liking) and technological traits (pH, colour, texture, cooking loss and yield). Otherwise, reduction in sodium chloride to 50% significantly decreased perceived saltiness (4.15 vs. 4.73; P < 0.05) and reduced microbial shelf life by 1 day when compared to control, even if there was still no effect on technological traits. In conclusion, it is feasible imparting an added value for processed rabbit meat products by reduction in sodium content that could increase market interest.     

Shelf life of Merino lamb meat retail packaged under atmospheres of various compositions

The effect of four different gas mixtures on several characteristics of Merino fresh lamb meat quality was studied. Merino lamb meat was packed under four different atmospheres (Batch 1: Ambient air; Batch 2: 70% O₂ + 30% CO₂; Batch 3: 80% O₂ + 20% CO₂ and Batch 4: 30% CO₂ + 69.6% Ar + 0.4% CO) and stored in darkness and under refrigeration (3 ± 1 °C) for 12 days. pH values and weight losses of lamb meat showed no significant changes during 12 days storage (P > 0.05) and were not affected by the different used atmospheres (P > 0.05). Lightness (L*) was not significantly affected by gas atmospheres until day 12 of storage, lamb meat packed in contact with air (Batch 1) showing the lowest lightness (P < 0.001). Samples in contact with ambient air, presented the lowest a*‐values during most of the storage period (P < 0.001). Batch 4 (30% CO₂ + 69.6% Ar + 0.4% CO) showed the highest a*‐values after 7 days storage. Batches 2, 3 and 4 presented a lower microbial count of total aerobic bacteria and Enterobacteriaceae than batch 1 (P < 0.05), whereas for lactic acid bacteria counts there were not significant differences (P > 0.05).     

Impact of pulsed electric fields and post‐mortem vacuum ageing on beef longissimus thoracis muscles

The impact of pulsed electric field (PEF) processing (0.2–0.6 kV cm^?1, 1–50 Hz, 20 μs) followed by vacuum ageing (1 and 3 days) on the quality traits of beef longissimus thoracis (LT) was assessed. The results show that pH, colour stability (L*, a* and R630/580 values) and cooking loss were unaffected by PEF treatments, whilst moisture content significantly (P < 0.05) decreased by 0.7–3.6%. No significant (P > 0.05) difference was found in shear force between PEF treated and untreated samples. However, the shear force values significantly reduced in response to ageing times regardless of the PEF treatments. After 3 days post‐treatment ageing, the shear force decreased by 20–22% compared to 1 day ageing for all samples. Furthermore, Cryo‐SEM results suggest that PEF treatments have led to more porous tissue structure leading to more water loss. Protein profile was unchanged by PEF treatments applied.     

Effect of salt content on gelation of normal and wooden breast myopathy chicken pectoralis major meat batters

This study investigated the effects of salt content (0–4%) on water holding capacity (WHC), textural characteristics, rheological properties, and microstructure of cooked normal (NOR) and wooden breast (WB) chicken meat batters. Results indicated with 0–2% salt addition, the WB batters had significantly lower WHC and storage modulus (G’) compared with the NORs (P < 0.05). However, these differences were eliminated when salt contents were increased to 3% or 4%. In addition, the NORs formed more regular and pored networks than the WBs (0–2%). Salt level significantly affected the textural properties of both batter types (P < 0.05). The hardness of the WB batters was lower than NORs at all NaCl levels (P < 0.05). Overall, compared with NORs, the WB batters showed inferior gelation properties at salt contents of 0–2%, while increasing salt content to 3–4% can improve the WHC and microstructure of gels.     

Effects of gas composition in modified atmosphere packaging on the meat quality of Spanish Manchega lamb

The effects of four types of packaging atmosphere, each with a different gas composition (20–80% CO₂), on the meat quality of Spanish Manchega lamb were examined in order to suggest a gas composition for optimal preservation. Meat quality was assessed by pH, colour (L*,a* and b* values), water‐holding capacity (WHC), cooking loss (CL) and shear force (SF). Gas composition affected all parameters except L* and SF. The pH values decreased significantly in samples packed with 80% CO₂ but remained constant in the other groups. The b* values were lower in samples packed without O₂ than in the other groups and increased with time. However, the a* values decreased in all groups with time. Samples packed in low‐CO₂ atmosphere tended to lose more water (ie to have less WHC and show more CL). The SF values decreased with time, and similar values of this parameter were observed for all treatments. © 2001 Society of Chemical Industry     

Irradiated vacuum-packed lamb meat stored under refrigeration: Microbiology,physicochemical stability and sensory acceptance

Reducing spoilage and indicator bacteria is important for microbiological stability in meat and meat products. The objective was to evaluate the effect of different doses of gamma radiation on the shelf-life of lamb meat, vacuum-packed and stored under refrigeration, by assessing the microbiological safety, physicochemical stability and sensory quality. Lamb loin cuts (Longissimus dorsi) were irradiated with 1.5 kGy and 3.0 kGy. The samples, including control, were stored at 1 ± 1 °C during 56 days. Samples were analyzed on zero, 14, 28, 42 and 56 days by their microbiological and physicochemical characteristics. Sensory quality was carried out on day zero. The results showed a reduction (p < 0.05) in the microbial load of the irradiated samples. The acceptance of lamb loins was not affected (p > 0.05) by the radiation doses. Thus gamma irradiation at 3.0 kGy was effective in reducing the content of microorganisms, without harming the physicochemical characteristics evaluated.