Solubility, absorption and desorption of carbon dioxide in chicken breast fillets

The solubility for carbon dioxide (CO₂) in skinless chicken breast fillets was investigated. Henry's constant for chicken breast fillets was calculated to be 42.8 ± 3.7 Pa (mg kg^-1)^-1 at 275 K.In addition, the effects of soluble gas stabilization (SGS) time and waiting time before MA packaging on amount of solubilized CO₂ were investigated. Increasing SGS treatment time, significantly (P < 0.001) increased the amount of dissolved CO₂, while increasing waiting time significantly (P < 0.001) reduced the dissolved CO₂. Desorption of CO₂ showed to be a time consuming process, giving the industry enough time to repackage SGS treated products without loosing vast amounts of dissolved CO₂.     

Modified atmosphere packaging inhibits browning in fennel

The effects of modified atmosphere packaging (MAP) to inhibit browning of the butt end cut zone of fennel bulbs stored during 14 days at 0°C followed by complementary air storage during 3 days at 15°C were studied. Selected bulbs were placed in 35 μm oriented polypropylene bags or in plastic baskets heat-sealed with nonperforated or perforated (control) polypropylene film. Changes in respiratory rate, ethylene emission, colour of both external leaves and butt end cut, as well as chemical and sensory attributes and browning development were monitored. A low to moderate nonclimacteric respiratory behaviour at 0°C with a respiration rate of 8-9 mg CO₂ kg⁻¹ h⁻¹ and an ethylene emission of 0.2-0.5 μl C₂H₄ kg⁻¹ h⁻¹ were found. Development of fungal attacks, chilling injury, decay and browning of external leaves were not detected for any treatment. All the MAP inhibited browning development of the butt end cut when evaluated after cold storage. However only the atmosphere of 6-7 kPa O₂ and 10-12 kPa CO₂ delayed that process at the end of complementary shelf life.     

Effect of Modified Atmosphere Packaging and Soluble Gas Stabilization on the Shelf Life of Skinless Chicken Breast Fillets

The suitability of soluble gas stabilization (SGS) to dissolve CO₂ into skinless chicken breast fillets before modified atmosphere (MA) packaging (MAP) was investigated. Head space gas composition (%), top web deflation (mm), muscle surface color (Minolta L*a*b*), pH, exudates in the packages (%), microbial characteristics, and off‐odor were assessed in the packaged fillets. Increased SGS treatment time (2 versus 12 h) before MA packaging increased the CO₂ content in the packaged fillets and counteracted package collapse. High package filling degree (51.8%) (low gas to product volume ratio) gave significantly (P < 0.001) lower CO₂ content in head space than normal filling degree (29.7%). Color, pH, and package exudates were not affected by SGS treatment. Aerobic plate count (APC), Enterbacteriaceae count (EC), and lactic acid bacteria (LAB) increased significantly (P < 0.001) at each sampling during storage (5, 11, 17, and 24 d). SGS treatment significantly (P < 0.015) decreased APC, EC, and Pseudomonas spp. counts (PC) compared with no SGS treatment. Filling degree did not have a significant effect on the investigated microbiological characteristics. Off‐odor scores correlated highest with EC (r²_(adj)= 0.82). Fillets SGS treated in 12 h were the only one not rejected at off‐odor evaluation on day 24. The samples stored in air spoiled after 5 d. SGS treatment in combination with MAP can be used successfully on chicken breast fillets to improve the microbiological (APC, EC, and PC) and sensorial characteristics, and in addition reduce package collapse and possibly increase the filling degree.     

Effects of skin and grilling method on formation of heterocyclic amines in chicken pectoralis superficialis muscle

Mutagenic heterocyclic amines (HAs) originate in processed proteinaceous foods. The effects of the presence of skin (with vs. without) and of grilling method (two plate vs. infrared) on the content of HAs in grilled chicken pectoralis superficialis muscle (temperature, 220 °C) were investigated. HA precursors (creatine, creatinine, free amino acids and carbohydrates) and HAs of these raw and grilled breast muscles were determined. The muscles originated from 24 birds of either sex (provenance Ross; aged 40-45 days). The HA content was determined in homogenates of the upper and lower surface slices of the grilled muscles (T_i = 82 °C). A higher content of total free amino acids was seen for the muscle (27.1 mmol kg⁻¹ raw meat) than for the skin (21.7 mmol kg⁻¹ raw meat). The creatine, creatinine and carbohydrate levels in the skin were below the limits of detection. The contents of creatine (31.8-38.7 mmol kg⁻¹) and creatinine (0.24-0.33 mmol kg⁻¹) in the breast muscle were determined. Relatively high levels were seen for glucose (23 mmol kg⁻¹ raw meat) and fructose (10 mmol kg⁻¹ raw meat) in the muscle, with other sugars present at low levels (<2 mmol kg⁻¹ raw meat). For the chicken muscle grilled on a two-plate grill, the contents of total HAs (PhIP, MeIQx, DiMeIQx, Harman and Norharman) were lower with the skin in place than in the muscle grilled without the skin (3.5 μg kg⁻¹vs. 4.8 μg kg⁻¹). Also, during infrared grilling with the skin, lower amounts of HAs were formed than with grilling on the two-plate grill (2.4 μg kg⁻¹vs. 3.5 μg kg⁻¹). On average, the infrared-grilled samples with skin contained 3-fold more total HAs than similar samples without the skin (2.4 μg kg⁻¹vs. 0.8 μg kg⁻¹), with the highest levels seen for PhIP and MeIQx.     

Inhibition of lipid damage in refrigerated salmon (Oncorhynchus kisutch) by a combined treatment of CO2 packaging and high-pressure processing

The effect of a previous combined treatment (CO₂-enriched modified atmosphere packaging, MAP and high-pressure processing, HPP, 150 MPa/5 min) on lipid stability of refrigerated (10 days/4 °C) salmon (Oncorhynchus kisutch) was studied. The following processing conditions were compared: B-0 (fish without MAP or HPP), B-1 (fish packaged under MAP and without HPP), B-2 (fish subjected to HPP without MAP) and B-3 (fish subjected to MAP and HPP). An inhibitory effect (P < 0.05) on lipid hydrolysis and oxidation was obtained by the presence of CO₂ in the packaging medium; values detected at day 10 for B-0 and B-1 fish were 80.72 and 49.61 (g free fatty acids, FFA, kg⁻¹ lipids), 6.14 and 2.81 (meq active oxygen kg⁻¹ lipids; peroxide value), 5.05 and 3.10 (mg malondialdehyde kg⁻¹ muscle), and 5.56 and 2.70 (fluorescence ratio), respectively. Furthermore, inhibition of lipid damage was observed for HPP alone; values detected at day 10 for B-2 fish were 76.24 (g FFA kg⁻¹ lipids) and 5.28 (meq active oxygen kg⁻¹ lipids). The lowest average values for lipid hydrolysis and oxidation were obtained in samples corresponding to the combined treatment (B-3 batch), differences being significant (P < 0.05) at day 10 for FFA (41.43 g kg⁻¹ lipids), peroxide (1.84 meq kg⁻¹ lipids) and fluorescence (2.50) values.     

Freezing of potato tissue pre-treated by pulsed electric fields

The effects of pulsed electric fields (PEF) pre-treatment on the freezing, freeze-drying and rehydration behavior of potato were studied. Potato samples (26 mm diameter, 10 mm high) were treated by PEF (400 V/cm) for various durations between 10⁻⁴ and 0.3 s. The degree of tissue damage was quantified by the change in electrical conductivity. PEF treated and untreated samples were either frozen in an air-blast freezer with air at −35 °C and 2 m/s velocity or freeze-dried at 0 °C and 0.04 mbar pressure and then rehydrated in water at 25 °C. The freezing times for PEF pre-treated samples reduced as the PEF-induced tissue damage increased. Scanning electron microscope images of the air-blast frozen and then freeze-dried samples showed increased deformation of cells and larger intercellular spaces (frozen samples only) for the PEF pre-treated samples. However, PEF pre-treatment improved the rate of freeze-drying and improved the quality and rehydration of the samples.     

Contents of biologically active polyamines in chicken meat,liver, heart and skin after slaughter and their changes during meat storage and cooking

Dietary polyamines, putrescine, spermidine (SPD) and spermine (SPM), participate in an array of important physiological roles, including tumour growth. Thus, reliable information on polyamine content in foods has been needed. We therefore determined polyamine contents in chilled chicken meat and giblets (n = 20) and skin (n = 10) 24 h after slaughter. The polyamines were determined, after extraction with perchloric acid, as dansyl derivatives, using an HPLC method. Mean SPD values were 4.8, 10.2, 11.4, 48.7 and 12.1 mg kg⁻¹ and SPM values were 36.8, 38.0, 24.3, 133 and 82.7 mg kg⁻¹ in breast, thigh, skin, liver and heart, respectively. Significant statistical correlations between SPD and SPM contents were observed in breast, thigh, skin and liver, whereas correlations were insignificant in heart. An increase of SPD and SPM was apparent in breasts and thighs stored at −18 °C for 6 months; however, it was significant only for SPM in thighs. The losses of both SPD and SPM were statistically insignificant during storage of aerobically packaged breasts up to 9 days at +2 °C. A significant decrease of SPM to about 60% of the initial contents was observed in both vacuum-packaged and in modified atmosphere (20% CO₂ and 80% O₂)-stored breasts on day 21 at +2 °C. For both SPD and SPM, roasting, grilling and frying of fresh breasts caused losses of about 40–60% of the initial contents (higher than boiling and stewing). Similarly, losses of SPM, due to roasting of breasts frozen for 3 or 6 months, were higher than those caused by stewing. Putrescine was detected only sporadically and at levels close to the detection limit of 1.0 mg kg⁻¹ (fresh matter).     

Investigation on the presence of sulphites in fresh meat preparations: estimation of an allowable maximum limit

Sulphiting agents are commonly used food additives. They are not allowed in fresh meat preparations. In this work, 2250 fresh meat samples were analysed to establish the maximum concentration of sulphites that can be considered as “natural” and therefore be admitted in fresh meat preparations. The analyses were carried out by an optimised Monier-Williams Method and the positive samples confirmed by ion chromatography. Sulphite concentrations higher than the screening method LOQ (10.0 mg · kg^− 1) were found in 100 samples. Concentrations higher than 76.6 mg · kg^− 1, attributable to sulphiting agent addition, were registered in 40 samples. Concentrations lower than 41.3 mg · kg^− 1 were registered in 60 samples. Taking into account the distribution of sulphite concentrations obtained, it is plausible to estimate a maximum allowable limit of 40.0 mg · kg^− 1 (expressed as SO₂). Below this value the samples can be considered as “compliant”.     

A novel quantum dot-based fluoroimmunoassay method for detection of Enrofloxacin residue in chicken muscle tissue

A rapid indirect competitive fluorescence-linked immunosorbent assay (cFLISA) based on quantum dots (QDs) as the fluorescent marker has been developed for the detection of Enrofloxacin (ENR) in chicken muscle tissue. The end-point fluorescent detection system was carried out using QDs conjugated with goat anti-mouse secondary antibody. The cFLISA method allowed for ENR determination in a liner working range of 1–100 ng mL⁻¹ with the 50% inhibition value (IC₅₀) of 8.3 ng mL⁻¹ and the limit of detection (LOD) of 2.5 ng mL⁻¹. The recoveries for chicken muscle samples spiked with ENR at levels of 50–200 μg kg⁻¹ ranged from 81% to 94% with coefficients of variation (CV) of 10–13%. In real chicken tissue sample analysis, the results of cFLISA were similar to those obtained from an indirect competitive enzyme-linked immunosorbent assay (cELISA) to a high performance liquid chromatography method (HPLC), which indicated that cFLISA is suitable as screening method for the monitoring of veterinary drug residues.     

Packaging-specific influence of chitosan on color stability and lipid oxidation in refrigerated ground beef

We examined the influence of chitosan on lipid oxidation and color stability of ground beef stored in different modified atmosphere packaging (MAP) systems. Ground beef patties with chitosan (1%) or without chitosan (control) were packaged either in high-oxygen MAP (HIOX; 80% O₂ + 20% CO₂), carbon monoxide MAP (CO; 0.4% CO + 19.6% CO₂ + 80% N₂), vacuum (VP), or aerobic packaging (PVC) and stored at 1 °C. Chitosan increased (P < 0.05) redness of patties stored in PVC and CO, whereas it had no effect (P > 0.05) in HIOX. Chitosan patties demonstrated lower (P < 0.05) lipid oxidation than controls in all packaging. Control patties in PVC and HIOX exhibited greater (P < 0.05) lipid oxidation than those in VP and CO, whereas chitosan patties in different packaging systems were not different (P > 0.05) from each other. Our findings suggested that antioxidant effects of chitosan on ground beef are packaging-specific.     

Protein and lipid oxidative stability of fresh ostrich M. Iliofibularis packaged under different modified atmospheric packaging conditions

This study investigated the aptness of modified atmospheric packaging (70:30, O₂:CO₂ (O_MAP); 70:30, N₂:CO₂ (N_MAP)) and traditional overwrap (control) for fresh ostrich steaks, stored at 4 ± 1 °C for 10 days. N_MAP showed the least oxidation, O_MAP the highest and the control moderate. Myoglobin (CIE a^∗) was gradually oxidised in all packaging atmospheres, but the O_MAP oxidised at the slowest rate, remaining significantly more bloomed from day 0 (17.86 ± 1.17) to 8 (9.78 ± 1.12). Free carbonyls were constant in all packaging environments. TBARS remained constant for the N_MAP (2.39 ± 0.21 mg MDA/kg meat) and the overwrap (3.06 ± 0.29 mg MDA/kg meat), but the O_MAP increased significantly (9.96 ± 1.02 mg MDA/kg meat) to day 10. The pH increased in the control but remained constant in the MAP treatments. The control also showed the greatest drip loss (>5%). The success of MAP application to ostrich will depend on the ability of the consumer to detect the by-products of lipid oxidation.     

Determination of lead and cadmium in food samples by the coprecipitation method

In this study, the coprecipitation method developed using a combination of 2-mercaptobenzothiazole (MBT) as a chelating reagent and copper as coprecipitate carrier was used for the determination of trace lead and cadmium in various food samples by graphite furnace atomic absorption spectrometry (GFAAS). The method was applied for the determination of Pb(II) and Cd(II) in salami, sausage, chicken, anchovy, spinach, cabbage, onion, dill, parsley, lettuce, tea and rice samples. The matrix modifiers were added as 50 μg NH₄H₂PO₄ + 3 μg Mg(NO₃)₂ for both Pb(II) and Cd(II). The signals were measured as peak area. The concentrations of Pb(II) and Cd(II) in the food samples were found to be in the range of 6.63 ng g⁻¹ (anchovy) −3.30 μg g⁻¹ (spinach) and 2.67 ng g⁻¹ (salami) −0.51 μg g⁻¹ (lettuce), respectively.     

Effect of processing and storage of Jameed on conjugated linoleic acid content and fat and cholesterol oxidation

The influence of Jameed processing and storage on fat and cholesterol oxidation, hydrolytic rancidity, and conjugated linoleic acid (CLA) was evaluated by determining peroxide value (PV), 7-ketocholesterol, free fatty acids content (FFAs) and total CLA. Three different sizes of Jameed pieces (ca. 50, 200 and 400 g balls) were used to investigate the influence of storage for 0, 1, 3, 5 and 7 months on the above lipid oxidation parameters. No significant (P>0.05) effect of the Jameed processing steps on lipid changes was found with the exception of the sun drying steps, that caused an increase of PV, 7-ketocholesterol and FFA contents and a decrease in CLA content. This trend was also observed during storage of Jameed at room temperature and kept exposed to light and atmospheric air. The PV values of the 50, 200 and 400 g balls after 7 months of storage were 35.3, 19.4 and 20.4 meq O₂ kg⁻¹ of fat, that were 17, 11 and 12 times higher compared with the corresponding values of the fresh samples (1.9 meq O₂ kg⁻¹ of fat ). The 7-ketocholesterol of the tested samples increased from about 5.7 μg g⁻¹ to 210, 120 and 125 μg g⁻¹ for the 50, 200 and 400 g balls, respectively. FFA content increased remarkably during storage, from about 1.3 g kg⁻¹ at the beginning of storage to 8.6 g kg⁻¹ of fat after 7 months with no significant (P>0.05) effect for the size of Jameed pieces on FFAs content. On the contrary, a decrease of about 43%, 26% and 26% of the original value (5.7 mg kg⁻¹ of fat) in CLA content was found for the stored Jameed pieces of 50, 200 and 400 g, respectively.     

Simplified pesticide multiresidues analysis in fish by low-temperature cleanup and solid-phase extraction coupled with gas chromatography/mass spectrometry

A simple and fast method for the simultaneous analysis of thiobencarb, deltamethrin and 19 organochlorine pesticide residues in fish by gas chromatography–mass spectrometry was investigated in this study. Samples are extracted with acetonitrile. Most of lipids in the extract are eliminated by low-temperature cleanup, prior to solid-phase extraction cleanup. The lipids extracted from the fish samples were easily removed without any significant losses of the pesticides. Aminopropyl (NH₂) cartridge was effective to eliminate the remaining interference. Spiked experiments were carried out to determine the recovery, precision and limits of detection (LODs) of the method. The method detection limits ranged from 0.5 μg kg⁻¹ to 20 μg kg⁻¹, whilst recoveries of the pesticides were in the range of 81.3–113.7% with relative standard deviations ?13.5% at a spiked concentration of 0.05 mg kg⁻¹, 0.02 mg kg⁻¹ and 0.1 mg kg⁻¹. The newly developed method is demonstrated to give efficient recoveries and LODs for detecting pesticide multiresidues in fish.     

Monitoring of fatty acid composition in virgin olive oil by Fourier transformed infrared spectroscopy coupled with partial least squares

A rapid Fourier transformed infrared (FTIR) attenuated total reflectance (ATR) spectroscopic method was applied to the determination of fatty acid (FA) profile and peroxide value (PV) of virgin olive oil. Calibration models were constructed using partial least squares (PLS) regression. A FA calibration model was constructed in the spectral range from 3033 to 700 cm⁻¹. Oleic acid (62.0–80.0%), linoleic acid (5.3–15.0%), saturated fatty acids (SFA, 12.6–19.7%), mono-unsaturated fatty acids (MUFA, 64.4–81.0%) and poly-unsaturated fatty acids (PUFA, 6.0–15.9%) were considered for chemometric analysis. PV (5.7–15.7 meq O₂ kg⁻¹) was calibrated using the signal of the full spectral range 4000–700 cm⁻¹ with first derivative pre-treatment. The LODs of the FTIR-chemometric methods were: 3.0% for oleic acid, 0.5% for linoleic acid, 1.3% for SFA, 3.0% for MUFA, 0.3% for PUFA and 1.0 meq O₂ kg⁻¹ for PV. Analytical methods were evaluated by use of validation samples (n = 25 for all the FA related parameters and n = 10 for PV) with nearly quantitative recovery rates (98–103%). The proposed method provided results comparable to official procedures, with the advantages of being less expensive and more rapid.     

Color-stabilizing effect of lactate on ground beef is packaging-dependent

Previous research on lactate-induced color stability in ground beef did not address the potential influence of packaging. The objective of the present study was to examine the effects of lactate on the color stability of ground beef patties stored in different modified atmosphere packaging (MAP) systems. Ground beef patties with either 2.5% potassium lactate or no lactate were packaged in vacuum (VP), high-oxygen MAP (HIOX; 80% O₂ + 20% CO₂), carbon monoxide MAP (CO; 0.4% CO + 19.6% CO₂ + 80% N₂), or aerobic packaging (PVC) and stored for 0, 2, or 4 days at 2 °C. Lactate-treated patties were darker (P < 0.05; lower L∗ values) than control patties. Surface redness (a∗ values) was greater (P < 0.05) for lactate patties than the controls when stored in PVC, HIOX, and VP. However, lactate’s effects on a∗ values were not evident when packaged in CO (P > 0.05). The color-stabilizing effect of CO could have masked lactate’s effect on surface redness. While lactate patties in PVC and VP demonstrated lower (P < 0.05) discoloration than controls, no differences (P > 0.05) existed between controls and lactate samples in CO and HIOX. Our results indicated that the effects of lactate on ground beef color are dependent on packaging.     

The suitability of plasma powder for cold-set binding of pork and restructured dry ham

To determine the ability of cold-set binder plasma powder (PP) for manufacturing restructured deboned dry ham, the effect of meat pre-treatment and PP preparation on the binding rate (k) and maximum binding force (BF_max) of pork model systems and deboned ham were evaluated. In pork model systems, the highest values for k (about 0.4 Ncm^− 2 h^− 1) and BF_max (about 2.5 Ncm^− 2) were obtained when powder or rehydrated plasma [in water or in NaCl aqueous solution at 0.5%] was applied onto the meat surface without additional pre-treatment or prior immersion in saline aqueous solution. Similar meat pre-treatment and PP preparation were used to restructure fresh deboned leg resulting in stable meat binding performances during salting and drying. An important increase in the binding force (BF_max > 10 Ncm^− 2) occurred over the drying period (after 4 weeks). Scanning electron microscopy showed different morphologies of the binding area, mainly depending on whether powder or rehydrated plasma was used.     

Physical properties and microstructure of pidan yolk as affected by different divalent and monovalent cations

Changes in physical property and microstructure of pidan yolk were monitored during pickling in the presence of different divalent (CaCl₂, MgCl₂) and monovalent (KCl) cations at different levels (2 and 5 g kg⁻¹) up to 3 weeks, followed by ageing for another 3 weeks. Pidan prepared following the commercial process, in which PbO₂ or ZnCl₂ at a level of 2 g kg⁻¹ was incorporated, was also tested. Hardness, hardening ratio, NaCl content and pH of yolk gradually increased, whereas moisture content, cohesiveness and adhesiveness decreased as the pickling/ageing time increased up to 6 weeks, regardless of cations used. During pickling/ageing, L* and b* values of interior yolk and a* of exterior yolk decreased, while L* and b* values of exterior yolk and a* value of interior yolk increased (P < 0.05). Yolk of pidan treated with PbO₂ at a level of 2 g kg⁻¹ was semisolid with lower hardening ratio, hardness, cohesiveness and adhesiveness, compared with those from other treatments. Those treated with ZnCl₂ or CaCl₂ at a level of 2 g kg⁻¹ yielded higher hardening ratio, hardness and cohesiveness but lower adhesiveness than others. Confocal laser scanning microscope indicated that the greater dehydration and release of lipids took place in pidan yolk during pickling/ageing of 6 weeks.     

Effect of chemical and physical pretreatments on the convective drying of cape gooseberry fruits (Physalis peruviana)

Drying of cape gooseberry fruits is a slow process because of the low permeability to moisture of the fruit’s waxy skin. In this work, the effect of chemical pretreatments (sunflower oil/K₂CO₃ or olive oil/K₂CO₃ at 28 °C, and NaOH/olive oil at 96 °C) and physical pretreatments (blanching) to break down the waxy surface and accelerate moisture diffusion during drying, was assessed. Drying was carried out at 60 °C and 2 m/s air velocity for 10 h. The lowest moisture content (0.27 kg water/kg db), the highest vitamin C content (0.36 mg/g), and the greatest rehydration capacity (1.89) were obtained in fruits pretreated with olive oil (9.48%) and K₂CO₃ (4.74%). However, the greatest changes in color (ΔE^* = 15.05) and chroma (ΔC^* = 9.03) were also associated to fruits pretreated with olive oil and K₂CO₃. The effective diffusivity of water during drying was 7.37 × 10⁻¹¹ m²/s in pretreated samples compared with 6.61×10⁻¹¹ m²/s for untreated samples.     

Effect of dehydration on the quality and storage stability of immature dates (Pheonix dactylifera)

Dates (Pheonix dactylifera) harvested from Kutch district of Gujarat, India were processed for the development of dehydrated dates. Dates grown in the Kutch region of Gujarat are harvested before maturation, i.e. Khalal stage to prevent spoilage caused due to rains. The processing and dehydration conditions for the preparation of dehydrated dates from immature date fruits were evaluated. Processing of dates by blanching in water at 96±1 °C and subsequent dehydration at 60±2 °C for 18-20 h resulted in good quality dehydrated dates as compared to the dates dried without heat treatment. The dehydrated dates were found to be acceptable with respect to colour, flavour, taste and overall quality. The dehydrated dates contained a total sugars of 520 g kg⁻¹, reducing sugars of 415.1 g kg⁻¹, tannins 13.5 g kg⁻¹ and ascorbic acid 33.7 mg kg⁻¹. Equilibrium relative humidity (ERH) of the dehydrated dates was found to be 75.9% with an initial moisture content of 159 g kg⁻¹. The dehydrated dates packed in 75 μ low-density polyethylene packaging material were shelf stable for 6 months at room temperature. The dehydrated dates remained acceptable during the storage period.