Content of biologically active polyamines in livers of cattle, pigs and chickens after animal slaughter

Dietary polyamines putrescine (PUT), spermidine (SPD) and spermine (SPM) participate in an array of important human physiological roles, including tumour growth. Physicians and dieticians thus need reliable information on polyamine contents in foods. However, data for livers are lacking. We determined therefore the content of these polyamines 24 h after slaughter in livers of young bulls, cows, pigs and chicken in 58, 19, 36 and 38 samples, respectively. Polyamines were determined as N-benzamides by micellar electrokinetic capillary chromatography. Mean PUT contents about 25 mg kg⁻¹ were found in cattle livers, while very low or negligible contents were determined in livers of the other animals. Extremely high mean SPD contents of 122 and 161 mg kg⁻¹ were found in livers of bulls and cows, respectively and mean levels of 32 and 57 mg kg⁻¹ in livers of pigs and chicken. An opposite relation was observed for SPM. Its mean contents were 43, 35, 115 and 120 mg kg⁻¹ for bulls, cows, pigs and chicken livers, respectively. Thus, livers of the tested animal species belong among foods with the highest polyamine contents. However, the contents ranged very widely, that makes application of the results for the control of human nutrition rather difficult. Polyamine contents in bovine blood were found to be below the detection limits of 2.1, 1.0 and 1.4 mg kg⁻¹ for PUT, SPD and SPM, respectively. Thus, the blood content did not contribute to the substantial polyamine contents in bovine liver found in this study.     

Levels of heavy metals in candy packages and candies likely to be consumed by small children

Ninety two samples of child-consumed candies and candy packages were analyzed for seven heavy metals. Lead (Pb) was detected at concentrations of 110.3–6394.1 mg kg⁻¹ in ten of 92 candy packages. The directive factor of Pb contamination had originated in the lead-based ink of the outer cover. Particularly, Pb was detected at high concentrations in case of green- or yellow-colored packages. Chromium (Cr) was detected at high concentrations in cases where Pb was also detected at high concentrations, and the Cr levels ranged from 136.9 mg kg⁻¹ to 1429.3 mg kg⁻¹ in seven of the 92 candy packages. Hexavalent chromium [Cr(VI)] was detected at 87–105.0% of the total Cr in polypropylene-coated wrappers with printed outer covers. The migration of Cr(VI) increased with elution time up to 0.20 μg (cm²)⁻¹ for 30 days in basic (pH 10.0) solution; however, there were no migrations in acidic (pH 4.0) and neutral (pH 7.0) solutions. The migration of Pb increased with elution time up to 0.65 μg (cm²)⁻¹ and 0.28 μg (cm²)⁻¹ in basic (pH 10.0) and acidic (pH 4.0) solutions, respectively. However, any migration was hardly observed in neutral (pH 7.0) solution.     

Evaluation of S-residues in grains and grain fractions fumigated with S-labelled carbonyl sulfide

³⁵S-labelled carbonyl sulfide (CO³⁵S) was used to measure the amount of sorbed ³⁵S residues and converted ³⁵S residues in grains and grain fractions after fumigation with CO³⁵S. Hard wheat, soft wheat, paddy rice, brown rice, polished rice, sorghum, maize, canola, barley, oats and peas were exposed for 4 days to 50 mg L⁻¹ of CO³⁵S with a total radioactivity of 20 mCi. After exposure, the samples were aired. The levels of ³⁵S residues varied with extraction solvent, e.g. 0.003–0.02 mg (COS equivalents) kg⁻¹ (grain) in chloroform extractions and 0.09–0.38 mg kg⁻¹ in water extractions. More than 90% of ³⁵S (COS equivalents) residues were in the water extractions. The total radioactivity determined by scanning radiation images (fluorescent image) of extractions and sectioned commodities ranged from 0.1 to 0.4 mg kg⁻¹. The radiation image shows that more than 90% of ³⁵S residues were located or distributed in the embryo, testa, pericarp and husk, and that the ³⁵S was still slowly desorbing from grains after 2 days aeration.     

Thermophysical properties of processed meat and poultry products

Thermophysical properties of various meat and poultry emulsions were evaluated at four temperatures (20, 40, 60 and 80 °C). Thermal conductivities (0.26–0.48 W m⁻¹ K⁻¹) increased linearly with temperature between 20 and 60 °C. Between 60 and 80 °C, it remained constant for most products except bologna. Curves for thermal conductivity as a function of temperature could be roughly grouped into two different categories: products containing meat particles and those containing meat emulsions. The application of various models was investigated for thermal conductivity prediction. It was found that a three phase structural based Kirscher model had the potential for predicting thermal conductivities with acceptable accuracy. Densities decreased slightly as a function of temperature from 20 to 40 °C. A transition phase was observed from 40 to 60 °C, which was followed by a decrease from 60 to 80 °C. There was a decrease of about 50 kg m⁻³ between the density of a raw product at room temperature (at maximum 1070 kg m⁻³) and the product heated to 80 °C (at minimum 970 kg m⁻³), due to the gelation or setting of the structure. After a transition period from 10 to 30 °C, the heat capacity increased linearly from 30 to 80 °C, and ranged from 2850 to 3380 J kg⁻¹ °C⁻¹, respectively. Densities and heat capacities were strongly influenced by the carbohydrate content (i.e. as the carbohydrate content increased the density decreased). The salt content adversely affected thermal conductivity and thermal diffusivity values. However, these parameters increased with moisture content.     

Diflubenzuron as a grain protectant for control of Sitophilus species

Diflubenzuron, applied to wheat at low doses (0.2–0.6 mg kg⁻¹), prevents development of first generation (F1) progeny of Sitophilus oryzae and S. granarius species except those developing from a short period of oviposition (1–2 weeks) immediately after application. These F1 progeny fail to produce F2 progeny when transferred to wheat dosed with diflubenzuron, and produce very few progeny when transferred to untreated wheat suggesting an effect on fertility in the adult insect. At 30°C, a dose of 0.4 mg kg⁻¹ is adequate to control S. oryzae and S. granarius, although a dose of 0.6 mg kg⁻¹ is required at 20°C. Strategies for use of diflubenzuron are discussed.     

Changes in the content of biologically active polyamines during storage and cooking of pig liver

Dietary polyamines putrescine (PUT), spermidine (SPD) and spermine (SPM) participate in numerous human physiological processes, including tumour growth. Eight experiments with pig liver were carried out. In two, livers were stored at -18°C for 168 days, in four, livers were stored aerobically (AE), vacuum-packaged (VP) and packaged in a modified atmosphere (MO; 70% N(2) and 30% CO(2), v/v) at +2°C for 9, 21 and 21 days, respectively, and in two, the effects of four cooking treatments were tested. Polyamines were determined as dansyl derivatives using an HPLC method. Distribution of both SPD and SPM in the four main liver lobes was homogenous. The initial SPD and SPM contents in 14 livers 24h after slaughter were 23.3±6.7 and 94.5±19.6mgkg(-1), respectively. The putrescine content was below the limit of detection. The content of SPD and SPM decreased during frozen-storage to about 70% of the initial values. On day-9 of storage, mean SPD and SPM contents decreased to about 85% of the initial values in livers stored in MO and to about 75-80% in AE and VP at 2°C. The decrease continued more extensively in VP than in MO. PUT was detected from day-15 of VP and MO storage. There was a significant decrease in SPD and SPM, to about 70-60% of the initial content during cooking.     

Sorption of chloroanisole vapors by raisin packaging material

The behavior and concentration of 2,4,6-trichloroanisole (TCA) vapors migrating into low-density polyethylene film (PE) of 0.39 μm at various temperatures and desorption of TCA from PE were determined. After 12 h exposure, 1642 μg g⁻¹ TCA was sorbed at 30 °C compared with 675 μg g⁻¹ at 20 °C. For PE to reach equilibrium of 4200 μg g⁻¹ at 30 °C took 48 h, but 120 h at 20 °C. The transmission of TCA through PE occurred after 12 h at 30 °C (8.9 μg kg⁻¹ m⁻² h⁻¹) and after 36 h at 20 °C (5.0 μg kg⁻¹ m⁻² h⁻¹). Desorption of TCA from PE increased with temperature. At 80 °C, 99% TCA was desorbed in 1 h compared to 51% at 40 °C, 31% at 30 °C and 17% at 20 °C. The rate of sorption, desorption and transmission of TCA vapors by PE is highly temperature-dependent.     

Diffusion of thiocyanate and hypothiocyanite in whey protein films incorporating the lactoperoxidase system

The diffusion of the thiocyanate (SCN⁻) and hypothiocyanite (OSCN⁻) components of a lactoperoxidase system (LPOS) in whey protein isolate (WPI) films was investigated. Diffusion coefficients for these molecules were measured for the LPOS-incorporated WPI films prepared with different WPI:glycerol ratios (1:1, 3:1, and 5:1). WPI film disks were coated on the surfaces of smoked salmon samples, and the samples were stored at 4, 10 and 22 °C. The diffusion coefficients were determined by fitting a mathematical model to the amounts of SCN⁻ and OSCN⁻ released from the disks during a period of time. The diffusion coefficients for SCN⁻ (D₁) and OSCN⁻ (D₂) in the films were 0.19–5.2 × 10⁻¹² m² s⁻¹ and 0.13–6.5 × 10⁻¹³ m² s⁻¹, respectively. The D₁ and D₂ decreased as the WPI:glycerol ratio increased and the storage temperature decreased. The E_a values for diffusion in 1:1, 3:1, and 5:1 WPI:glycerol films were 13.3, 29.5, and 35.6 kJmol⁻¹, respectively, for SCN⁻ and 15.8, 30.1, and 39.9 kJmol⁻¹, respectively, for OSCN⁻.     

Vascular effects and antihypertensive properties of κ-casein macropeptide

The blood-pressure-lowering effect of bovine κ-casein macropeptide (CMP), previously reported to exhibit a modest angiotensin-converting enzyme (ACE)-inhibitory activity in vitro, was evaluated in spontaneously hypertensive rats (SHR). The oral administration of CMP (150 mg kg⁻¹) significantly reduced the systolic blood pressure (SBP) of SHR. The antihypertensive action was more pronounced when CMP was treated with trypsin. The sequence MAIPPKK, identified in the tryptic hydrolysate of bovine CMP, significantly reduced blood pressure at a dose of 10 mg kg⁻¹. The CMP and its tryptic peptides induced relaxation of endothelium-intact aortic rings. The sequence MAIPPKK also evoked a significant relaxation effect; however, the shorter sequence MAIPPK and the strong ACE-inhibitory tripeptide IPP exhibited a vascular relaxing effect lower than 10%. The implications of vascular relaxing mechanisms, as well as the possibility that the tripeptide IPP is at least partially responsible for the antihypertensive effects of CMP, are discussed.     

The effect of ractopamine on myofibre distribution and morphology and their relation to meat quality in swine

One hundred and twenty-eight purebred Lacombe pigs (equal number of barrows and gilts) were assigned to one of four treatments at 64 kg and fed a commercial grower-finisher diet ad libitum to which ractopamine (RAC) was incorporated (0, 10, 15 or 20 mg kg⁻¹). Pigs were slaughtered at 100 kg. Histological samples were collected from the semimembranosus (SM) and the psoas major (PM) muscles from the 0 and 20 mg kg⁻¹ RAC groups. Meat quality and muscle composition data were collected for all pigs. A significant 3-way interaction for muscle weight involving treatment, muscle and gender (P = 0·01) indicated that for the SM, gilts appeared to respond to RAC at a lower level of incorporation (10 mg kg⁻¹) than barrows. Despite these differences in response at the gross muscle level, responses were similar at the cellular level for both muscles. The proportion of red fibres did not change (P = 0·21), the proportion of intermediate fibres decreased (P = 0·01) and the proportion of white muscle fibres increased (P = 0·02) in the mg kg⁻¹ RAC group compared to the controls. In addition, when compared to controls, average fibre diameters in the 20 mg kg⁻¹ RAC group remained constant in the red fibres, and increased significantly in both the intermediate and white fibres (P = 0·01 and 0·02, respectively). Over both muscles Kramer Press values were significantly higher (P = 0·030 in the RAC-fed pigs than in the controls. Incorporation of RAC into the diet did not result in any changes to crude protein or total and soluble hydroxyproline levels. Crude fat tended to increase in the 15 mg kg⁻¹ RAC treatment in the SM and decreased in the 20 mg kg⁻¹ RAC treatment in the PM. The shift in fibre type, and the associated changes in fibre size, may contribute to the increased shear values found in RAC-fed pigs.     

A new measure of uptake: desorption of unreacted phosphine from susceptible and resistant strains of Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae)

Previous studies of phosphine (PH₃) uptake by insects have concentrated on the process as a whole (“gross uptake”), without distinguishing between absorption of the gas and oxidation to non-volatile products. The lower gross uptake by phosphine-resistant (R) strains of stored product pests has given some insights into resistance mechanism(s). In this study, a recently described method of fumigant residue analysis in grains (microwave irradiation followed by headspace gas chromatography) was adapted to measure absorbed unreacted PH₃ (“reversible uptake”) in a susceptible (S) and an R strain of the rust red flour beetle Tribolium castaneum. At a concentration of 0.9 mg l⁻¹, S insects contained 20 ng g⁻¹ after 15 min exposure, rising slowly to 50 ng g⁻¹ after 5 h. The R strain yielded 190 ng g⁻¹ after 15 min, falling to 50 ng g⁻¹ over 5 h. Falling PH₃ content corresponded with increasing mortality in the R strain, while all except the shortest exposure killed 97% or more of the S strain. Insects of either strain, killed prior to PH₃ exposure by freezing in liquid nitrogen, contained 130–140 ng g⁻¹ after 30 min, rising to 190–200 ng g⁻¹ after 5 h. Gross uptake under the same conditions was 50 μg g⁻¹ (S) and 8 μg g⁻¹ (R) after 5 h, which accords with the literature. Reversible uptake by living insects of either strain under anoxia was 40–50 ng g⁻¹ over 30 min to 2 h. By examining the time-course of reversible PH₃ uptake, a new hypothesis of phosphine action and uptake, in which PH₃ oxidation in vivo is a consequence of reactive oxygen species generation, rather than a direct cause of toxicity, is discussed.     

The effect of nutritional supplements on growth rate, stress responsiveness, muscle glycogen and meat tenderness in pastoral lambs

Nutritional supplements and a magnesium bolus and were used in lambs in a 2×2 factorial design to investigate the effect on growth, preslaughter stress measurements, muscle glycogen, and meat quality. In total, 64 Perendale lambs were used (32.7±0.53 kg, mean±SEM). Feed supplemented animals received 150 g feed pellets day⁻¹ in addition to pasture grazing, and this increased growth from 183 to 207 g day⁻¹. Mean delivery of Mg from the boluses was 0.17 g day⁻¹ for 28 days, with no effect on growth rates, or any other of the variables measured. Urinary noradrenaline, adrenaline and cortisol did not differ between groups in the immediate pre-slaughter period. The meat ultimate pH was not different between groups and had a mean range of 5.47–5.53. Muscle residual glycogen did not differ between groups and had a mean range of 42–43 mmol kg⁻¹. Finally there were no differences in shear force values at all ageing times. The final shear force value of 2.5 kg F after 72 h ageing at 15 °C was a low value representing tender meat. These studies indicate that if nutrition is adequate and stress levels are low, there are no differences in meat tenderness of pasture fed lambs compared with those having feed supplements to increase growth rate.     

Thermal death kinetics and heating rate effects for fifth-instar Cydia pomonella (L.) (Lepidoptera: Tortricidae)

Thermal death kinetic parameters of fifth-instar codling moths (Cydia pomonella (L.)) and the effect of three heating rates (1°C min⁻¹, 10°C min⁻¹, and 18°C min⁻¹) on larval mortality were determined by a heating block system. The insects were heated to four temperatures (46°C, 48°C, 50°C, and 52°C) held for predetermined periods followed by 24 h storage at 4°C before mortality evaluation. Thermal death kinetics for fifth-instar codling moths followed a 0.5th order of kinetic reaction. Minimum time required to achieve 100% mortality of a given population decreased with temperature in a semi-logarithmic manner. No larval survival was observed in samples of 600 insects after exposure to 46°C, 48°C, 50°C, and 52°C for 50, 15, 5, and 2 min, respectively. Activation energy for thermal kill of fifth-instar codling moths at the heating rate of 18°C min⁻¹ was estimated to be about 472 kJ mol⁻¹. The lethal time accumulated during the ramp period was about 1.8, 0.2, and 0.1 min for the heating rates of 1°C min⁻¹, 10°C min⁻¹, and 18°C min⁻¹, respectively.     

Influence of temperature and surfactant on Escherichia coli inactivation in aqueous suspensions treated by moderate pulsed electric fields

This research employed a conductometric technique to estimate the inactivation kinetics of Escherichia coli cells in aqueous suspensions (1 wt.%) during simultaneous pulsed electric fields (PEF) and thermal treatments. The electric field strength was E = 5 kV/cm, the effective PEF treatment time t_PEF was within 0–0.2 s, the pulse duration t_i was 10^− 3 s, the medium temperature was 30–50 °C, and the time of thermal treatment t_T was within 0–7000 s. The damage of E. coli was accompanied by cell size decrease and release of intracellular components. The synergy between PEF and thermal treatments on E. coli inactivation was clearly present. The non-ionic surfactant Triton X-100 additionally improved its inactivation. The characteristic damage time followed the Arrhenius law within the temperature range 30–50 °C with activation energies W = 94 ± 2 kJ mol^− 1 and W = 103 ± 5 kJ mol^− 1 with and without the presence of surfactant, respectively. Relations between cell aggregation, cell ζ-potentials and presence of surfactant were analysed.     

The effect of air temperature, velocity and visual lean (VL) composition on the tempering times of frozen boneless beef blocks

Beef blocks of two compositions, 100% and 50% visual lean (VL), in standard commercial packaging with nominal dimensions of 510 × 390 × 150 mm were tempered from −18 °C to −3 °C using air at temperatures from 3 °C to −3 °C and velocities of 0.5 and 5 ms⁻¹. These conditions were then modelled using a finite difference mathematical model and the accuracy of the model assessed by comparison with the experimental results. An extended range of conditions (including an intermediate air velocity of 2 ms⁻¹ and an intermediate composition of 75% VL) was then modelled to produce data that can be used to design tempering processes.

The results show that single stage air tempering of even single blocks within their cartons needs to be a long process. In air at 3 °C and 5 ms⁻¹, blocks of 50% VL rose to deep temperatures of −10 °C and −3 °C after 4.0 and 22.5 h, respectively, while with 100% VL 4.6 and 27.3 h were required. Under these conditions, the surface layers of the meat would have spent many hours in a thawed condition that would be detrimental to both drip and optimal processing. Using lower temperatures avoids thawing and at the same time produces an optimum temperature difference for subsequent processing. However, tempering times are substantially extended. For example, times to the above temperatures using air at −1 °C and 5 ms⁻¹ were 4.8 and 37.5 h for 50% VL and 5.1 and 44.5 h for 100% VL.     

Effect of non-ionizing radiation (UVC) on the development of Trogoderma granarium Everts

Various instars of khapra beetle Trogoderma granarium were exposed to ultra-violet rays (UVC) to assess their effect on each instar and their potential in breaking the developmental cycle of the khapra beetle.

Eggs aged zero (recently laid), 24 and 48 h were exposed to UVC at a radiation intensity of 31.4±0.02 W m⁻². Doses equivalent to 3 min (56.52 J cm⁻²), 8 min (150.72 J cm⁻²), and 12 min (226.08 J cm⁻²) resulted in death of all eggs, with a hatch of 96.6% in the control.

Mortality of UVC-irradiated larvae increased proportionally with increase in UVC dose, while, for each dose, mortality was inversely related to age of larvae at irradiation. Thus, at a UVC dose of 56.52 J cm⁻², larval mortality was 98.3%, 93.3% and 83.3% and adult emergence was 1.7%, 6.7% and 11.7% for 1–9, 10–18 and 19–27 day-old larvae, respectively. Similar effects were observed for UVC doses 150.72 and 226.08 J cm⁻² with an increase in the overall mortality of larvae and a decrease in adult emergence. Effect of irradiation of 0, 24 and 48 h-old pupae with doses of UVC, was inversely related to age of pupae at irradiation. Thus, at 56.52 J cm⁻², mortality as pupae was 91.7%, 71.7% and 73.3% and adult emergence was 0%, 3.3% and 1.7% for 0, 24 and 48 h-old pupae, respectively. Premature emergence of deformed adultoids was 25% when 24 and 48 h-old pupae were irradiated with the above dose. At a dose of 225.08 52 J cm⁻² there was no adult emergence. Death as pupae was 98.3%, 96.7% and 78.3% and premature emergence was 1.7%, 3.3%, and 21.7% for pupae irradiated at 0, 24 and 48 h-old, respectively.     

Effect of a bacteriocin-producing Lactococcus lactis strain and high-pressure treatment on the esterase activity and free fatty acids in Hispánico cheese

The effect of milk inoculation with a bacteriocin-producing (BP) culture and of high-pressure (HP) treatment of 15-day-old Hispánico cheeses (400 MPa, 5 min, 10 °C), separately or combined, on the release of intracellular esterases and cheese lipolysis was investigated. Esterase activity and free fatty acids (FFAs) content increased during ripening of Hispánico cheese and palmitic, oleic and stearic acids being the most abundant FFAs. On day 15, the highest esterase activity was recorded for HP-treated BP cheese. The activity for HP-untreated BP cheese was the next highest. No difference in the activities was found between HP-treated and untreated cheeses made without BP culture. Total FFAs on day 15 were at a lower concentration in BP cheeses than in cheeses made without BP culture, probably due to the lower pH values of the former. The rate of total FFA accumulation from day 15 to day 50 was higher in BP cheeses (31.1–32.1% increase) than in cheeses made without BP culture (19.3–21.7% increase). The highest total FFA concentration on day 50 (612 mg kg⁻¹) was found for HP-untreated cheese made without BP culture.     

Aflatoxins in stored maize and rice grains in Liaoning Province, China

Aflatoxin contamination and its relationship to storage length in stored maize and rice in Liaoning Province, northeastern China, was investigated. Aflatoxins in 110 samples collected from an area of 14.68 million km² covering storage length from 1 yr to over 10 yr were determined by high-performance liquid chromatography with fluorescence detection. The results showed that almost all samples collected contained aflatoxins. The average contents in maize, whole grain rice and brown rice were found to be 0.99, 3.87 and 0.88 μg kg⁻¹, respectively. Three-fourths of the total aflatoxins in whole grain rice (3.87 μg kg⁻¹) could be removed by dehusking to as low as 0.88 μg kg⁻¹ in brown rice. No significant aflatoxin increase was observed in whole grain rice and brown rice over a 10-yr storage period. In maize, the amount of aflatoxins was significantly higher in 2-yr than 1-yr sample. Aflatoxin G₁ was detected as the major type of aflatoxin in over 40% of all stored grain samples tested and over 92% of rice samples examined. The aflatoxin content in maize and rice is much lower than the regulated maximum amount allowed in foodstuffs in China and other countries. We concluded that these grains are safe for human and livestock consumption and for trading.     

Changes of alanyl aminopeptidase activity and free amino acid contents in biceps femoris during processing of Jinhua ham

Sixty experimental Jinhua hams were processed by a traditional method. The potential alanyl aminopeptidase (AAP) activity in biceps femoris was determined. The effects of temperature, salt content, sodium nitrate content and pH on muscle AAP were evaluated using response surface methodology. Porcine muscle was found to possess very strong potential AAP activity that decreased gradually during processing from 201,635 U g⁻¹ before salting to 6147 U g⁻¹ after aging. Temperature, pH and salt content had significant exponential effects on AAP activity (P < 0.001). Both temperature and salt content interacted with pH in their effects on AAP activity (P < 0.01). However, 0–50 mg L⁻¹ sodium nitrate had no detectable effect on AAP activity (P > 0.05). The regression model showed muscle AAP maintaining its activity all through Jinhua ham processing, indicating that muscle AAP may generate free amino acids during the processing and storage of Jinhua ham. The concentrations of free amino acids increased significantly (P < 0.05) during Jinhua ham processing, except for arginine and cystine. The concentrations of most free amino acids were 5–20 times higher in the final product than in hams before salting. Final concentrations exceeded thresholds for sensory detection, thus implicating an important role of free amino acids in the determination of Jinhua ham flavor.     

The effects of spray and blast-chilling on carcass shrinkage and pork muscle quality

Combinations of blast- and spray-chilling of pork carcasses were compared to spray-chilling at conventional chilling temperatures with regard to carcass shrinkage during chilling and pork muscle quality. In experiment 1, pork sides were spray-chilled at 1°C for the first 10 h (40 spray cycles of 60-s duration every 15 min) of cooling or blast-chilled at −20°C for 1, 2 or 3 h followed by spray-chilling for 9, 8 or 7 h duration, respectively. All pork sides were then chilled to 24 h post mortem at 1°C. Experiment 2 followed the same procedures as experiment 1, except that −40°C was used as the blast-chill temperature.

Carcass shrinkage was similar for all treatments in experiment 1 at 24 h ranging from 0·5–0·7 g 100 g⁻¹. Blast/spray-chilling increased the rate of chilling and reduced the rate of post-mortem pH decline in two muscles (longissimus thoracis, LT and semimembranosus, SM) compared to the combined conventional/spray-chill treatment. Carcasses that were blast-chilled for 3 h had LT muscles that were darker with a higher protein solubility, less drip loss, shorter lengths and higher shear values compared to those from carcasses in the conventional/spray-chill treatment. In experiment 2, carcasses blast-chilled for 3 h at −40°C recorded a weight gain at 24 h of 0·4 g 100 g⁻¹, compared to a weight loss in all other treatments (0·2–0·4 g 100 g⁻¹). Muscle colour was darker in both the LT and SM of carcasses blast-chilled for 3 h at −40°C compared to carcasses from the conventional/spray-chill treatment, but most other measurements of muscle quality showed an inconsistent response to chilling treatment.