Biologically active polyamines in pig kidneys and spleen: Content after slaughter and changes during cold storage and cooking

Polyamines putrescine, spermidine (SPD) and spermine (SPM) were determined as dansyl derivatives using an HPLC method. Distribution of SPD and SPM in pair kidneys was homogenous. The mean SPD and SPM contents in pig kidneys 24 h after slaughter were 9.39 ± 3.35 and 53.1 ± 14.0 mg kg⁻¹, respectively with no significant differences between barrows and gilts. Putrescine content was below the detection limit of 1.2 mg kg⁻¹. In kidneys stored aerobically or vacuum-packaged at 2–3 °C for 7 and 21 days, respectively, SPD and SPM decreased significantly. Stewing decreased both polyamines more extensively in kidneys processed on day-1 after slaughter than on day-7 after storage at 2–3 °C. The mean SPD and SPM in 10 spleens 24 h after slaughter were 36.7 ± 5.70 and 34.0 ± 7.64 mg kg⁻¹, respectively. Thus, both pork kidney and spleen are foods with a high level of SPM and SPD.     

Identification of halothane genotypes by calcium accumulation and their meat quality using live pigs

The three halothane genotypes (NN, Nn, and nm) were identified by measuring the capacity for Ca²⁺ accumulation by sarcoplasmic reticulum in whole muscle homogenate preparations of M. longissimus dorsi with a Ca²⁺ specific electrode at 35°C. Significant differences (P < 0·001) in deterioration (%) of Ca²⁺ accumulation, 12% for NN, 35% for Nn, and 81% for nn pigs, were observed after ageing the whole muscle homogenate preparations for 24 h in ice.

Predictions of meat quality in live pigs (n = 34) based on the values for water-holding capacity, assessed as fluid (g/0·5 g wet wt LD), and pH (fluid) by using small biopsy LD samples (Cheah et al. 1993) were performed on all the halothane genotypes. The halothane genotype NN (n = 11) showed a fluid value of 0·37 ± 0·01 and a pH (fluid) value of 6·62 ± 0·03 as compared with 0·61 ± 0·02 and 5·84 ± 0·04, respectively, for the halothane genotype nn (n = 13). The Nn pigs (n = 10) showed fluid (0·49 ± 0·03) and pH (fluid) (6·19 ± 0·11) values between those values observed for the two homozygotes (NN and nn). Predictions of meat quality in live pigs from biopsy LD muscles were confirmed from assessments on post-mortem LD muscles based on pH₁ and fibre optic probe (FOP) measurements.

The extent of deterioration (%) in Ca²⁺ accumulation showed high correlations with fluid (r = −0·861) and pH (fluid) (r = −0·831) in the biopsy LD samples, and with pH₁ (r = 0·663), FOP (r = −0·812), and drip (%) loss (r = −0·777) in the post-mortem LD samples.     

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.     

A comparison of the toxicity of pirimiphos-methyl and malathion to Typhaea stercorea (L.) when applied to stored maize

The toxicity of freshly applied and aged residues of pirimiphos-methyl and malathion were assessed against adult Typhaea stercorea (L.). Maize was treated with each pesticide at doses of 2, 4, 6, and 8 mg kg⁻¹ and stored at a constant 25 °C and 70% r.h. for 12 weeks. All fresh deposits of pirimiphos-methyl produced 100% mortality as did malathion at 4, 6 and 8 mg kg⁻¹. After four weeks storage pirimiphos-methyl still gave 100% mortality at 6 and 8 mg kg⁻¹ but this dropped to 96% at 4 mg kg⁻¹ and 60% at 2 mg kg⁻¹, while mortality for malathion was less than 31% even at 8 mg kg⁻¹. After 12 weeks storage only pirimiphos-methyl gave effective control with 78% mortality at the highest dose of 8 mg kg⁻¹, while control by malathion had completely broken down. The effect of exposure time on T. stercorea for both pesticides at a single dose of 4 mg kg⁻¹ was also assessed. Beetles were left in contact with treated maize for 2, 4, 6, 8 and 10 d. Fresh and four-week-old pirimiphos-methyl residues produced over 98% mortality at all exposure periods but on 12-week-old residues mortality had dropped and was only 61% following 10 d exposure. Only freshly applied malathion gave 100% mortality and even the maximum exposure of 10 d only produced 51% mortality of T. stercorea at four weeks and 39% at 12 weeks.     

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.     

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.     

Efficacy of the insect growth regulators methoprene, fenoxycarb and diflubenzuron against Rhyzopertha dominica (F.) (Coleoptera: Bostrichidae) on maize and paddy rice

The activity of fresh deposits of methoprene, fenoxycarb and diflubenzuron against F₁ progeny of Rhyzopertha dominica on maize and paddy was compared with that on wheat, at two equilibrium relative humidities. There were differences between slopes of log concentration-probit (lc-p) lines for different compounds, and for the same compound on different grains. Judging by values of the IC_99.9, i.e. the concentration which inhibited progeny production by 99.9%, the order of activity against F₁ progeny on different grains was: methoprene, wheat and paddy > maize; fenoxycarb, wheat > paddy > maize; diflubenzuron, wheat and maize > paddy. Equilibrium relative humidity (e.r.h.) had no consistent effect on activity—at 90% e.r.h., the IC₅₀ of fenoxycarb on wheat was reduced and the IC₅₀ of diflubenzuron on maize was increased compared with 70% e.r.h., and other treatments were unaffected.

The efficacy of these compounds on maize and paddy against F₁ and F₂ progeny was evaluated during 48 weeks storage at 30°C, 70% r.h. The resolved S isomer of methoprene was also included. Slopes of lc-p lines were greater against the F₂ than against the F₁, particularly using diflubenzuron on paddy, with corresponding smaller values of the IC_99.9. Equally effective concentrations did not decline systematically over 48 weeks. Minimum effective application rates were judged as the concentrations that prevented living F₂ progeny in at least 2 of 3 replicates. Estimates for 48 weeks protection on maize were: methoprene, 2 mg kg⁻¹; S-methoprene, 1 mg kg⁻¹; fenoxycarb, 10 mg kg⁻¹; and diflubenzuron, 5 mg kg⁻¹. Corresponding estimates on paddy were 0.15 mg kg⁻¹, 0.05 mg kg⁻¹, 5 mg kg⁻¹, and 5 mg kg⁻¹.     

Effect of genetic origin, diet and weaning weight on carcass composition, muscle physicochemical and histochemical traits in the rabbit

Fifty rabbits originating from the crossing of one dam strain with three sire strains, Hy+, INRA 9077 and INRA 3889, were studied. The adult body weights of the sire strains were 5·1, 4·1 and 3·1 kg, respectively. After weaning, the Hy+ and the INRA 9077 rabbits were fed either an H (11·99 MJ DE kg DM⁻¹) or L diet (9·67 MJ DE kg DM⁻¹). The INRA 3889 rabbits were fed only the H diet. In each of these five blocks, two weaning weights were studied and the rabbits were slaughtered when the average body weight of each block reached 2·5 kg. Slaughter yield, carcass fatness and hindleg meat to bone ratio were determined. Muscular tissue was described using (1) physicochemical criteria (ultimate pH, L^*a^*b^* colour) of the biceps femoris (BFE), tensor fasciae latae (TFL) and semimembranosus accessorius (SMA) muscles and (2) histochemical characteristics of the longissimus lumborum muscle (LL) through computerised image analysis (fibre type composition, cross-sectional area). At slaughter, the rabbits of INRA 3889 sire origin, which had the highest degree of maturity (72%), gave the best slaughter yield (p<0·01), the heaviest reference carcass weight (p<0·01), and highest LL proportion (p<0·01), hindleg meat to bone ratio (p<0·05) and fatness (p<0·01); their LL muscle showed the lowest percentage of βR fibres, while the cross-sectional area of their muscular fibres was the highest (p<0·05). When all sire × diet combinations were put together, the heavier the weaning weight, the lower the daily gain (p<0·01) and the lightness (L*) of thigh muscles (p<0·05). The lower the DE content of the diet, the lower the growth rate, the slaughter yield, the reference carcass weight (p<0·01) and the cross-sectional area of all types of muscle fibres of the rabbits of both Hy+ and INRA 9077 sire origin.     

Effect of the dietary supplementation with Vitamin E on colour stability of packaged, sliced pasteurized ham

The effect of dietary supplementation with vitamin E (200 IU kg⁻¹ feed) on the colour stability of pasteurized ham was studied. Pigs were fed on control and enriched diets for the last 12 weeks before slaughter. Pasteurized ham was manufactured from the hams from 6 barrows and 6 gilts per dietary group. Half of the samples of sliced ham from control and supplemented pigs were packaged under vacuum (VAC) and half in low-oxygen modified atmosphere packs (FOG, gas mixture: CO₂/N₂=60/40). Half the packages were kept under constant illumination and the other half in the dark, both for 22 days at 7°C. The redness component of the VAC-packaged ham prepared from vitamin E-supplemented pigs was slightly more stable than that of comparably packaged ham prepared from control pigs. The opposite was observed for the FOG-packaged products. Overall, colour changes were greater in the ham in FOG-packs than in the ham in VAC-packs. In addition, the colour of the FOG-packaged ham was clearly affected by illumination, whereas the colour of the VAC-packaged ham appeared more stable. It is concluded that dietary supplementation of pigs with vitamin E does not appear to offer significant advantages over currently used feeding regimens with regard to the quality of the ham produced.     

Formation of biogenic amines during the maturity process of raw meat products, for example of cervelat sausage

The raw meat product cervelat sausage with a diameter of 90 mm was investigated during maturation and storage over a period of about 12 weeks. The examination was carried out by ion exchange chromatography (amino acid analyzer) and included the amines ethylamine, propylamine, butylamine, putrescine, histamine, cadaverine, tyramine, β-phenylethylamine, spermidine and spermine. In addition, the starter bacteria cultures varied according to manufacturer. Over the duration of investigation, five different production batches were observed in parallel. During the maturity process and storage, after 87 days, tyramine (58.9 mg kg⁻¹) showed a clear dominance, followed by spermine (34.1 mg kg⁻¹), putrescine (26.1 mg kg⁻¹) and spermidine (8.7 mg kg⁻¹), if starter bacteria culture 1 was used. Other amines were not detected. The use of starter bacteria culture 2 led, after 87 days, to the highest content of putrescine (244.1 mg kg⁻¹), followed by tyramine (119.2 mg kg⁻¹), histamine (52.9 mg kg⁻¹), spermine (37.5 mg kg⁻¹) and spermidine (9.2 mg kg⁻¹). With the use of starter bacteria culture 3, for spermine and spermidine a comparable behavior was shown to that with culture 1 or 2. After 87 days, putrescine reached the highest value of 484.2 mg kg⁻¹, followed by tyramine (119.4 mg kg⁻¹) and histamine (111.0 mg kg⁻¹). Cadaverine (36.9 mg kg⁻¹) could also be determined. As an accompanying investigation, the parameters pH, water activity (a_w) and microbial count (lactobacilli, enterobacteria, staphylococci and yeast) were determined. An investigation of the sections center-middle-edge showed that the content of amines increases to its highest values in the middle. The edge showed the lowest content. This behavior correlates with the a_w distribution of a raw sausage.     

Ellipsometry across isolated muscle fibres indicates a refractive contribution to paleness in pork

Muscle fibres isolated from pork were mounted in a microscope chamber and pH was controlled with 0.2 M phosphate buffer. Optical path differences between ordinary and extraordinary rays were measured by ellipsometry while a scanning stage moved the fibre across the optical axis of the microscope. The depth of fibre in the optical axis was estimated from the lateral diameter of fibres. Path differences increased as fibre depth increased. Static ellipsometry of unmounted fibre fragments showed maximum path differences at pH 5.5 were higher than at pH 7.0, but variance was high and the difference was not significant (64.4±15.1 nm at pH 5.5 versus 58.9±15.2 nm at pH 7.0, P>0.05, n=40). However, the mean depth of fibre fragments at pH 5.5 was less than at pH 7.0 (53.9±15.1 μm at pH 5.5 versus 70.6±16.1 μm at pH 7.0, P<0.005, n=40). Thus, path differences per micrometre of fibre depth were greater at pH 5.5 than at pH 7.0 (1.25±0.37 nm^{−1 μm} at pH 5.5 versus 0.87±0.31 nm^{−1 μm} at pH 7.0, P<0.0005, n=40). As pH decreases, therefore, muscle fibre diameter decreases while birefringence increases. Refraction through muscle fibres may contribute to pork paleness.     

Comparison of nutritive chemistry of a range of temperate seaweeds

Eleven species of macroalgae (including four species from commercially important genera) were analysed for moisture, ash, fat, protein, neutral detergent fibre, crude fibre, calorific value, and calcium content. At the extremes of the nutritional values, Corallina officinalis had low calorific value (2.7 ± 0.3 MJ kg⁻¹), high ash content (77.8 ± 0.2% dw), low protein (6.9 ± 0.1% dw) and high calcium content (182 ppm); whereas the exploited Porphyra sp. had high calorific value (18.3 ± 1.8 MJ kg⁻¹), low ash content (9.3 ± 0.2% dw), high protein (44.0 ± 1.2% dw) and low calcium content (19.9 ppm). The other species considered had intermediate values, but tended to be more similar to Porphyra than to Corallina. When possible our data were also compared with those of other workers; they were found to be broadly similar.     

Effect of the RN(-) gene on ultrastructure and protein fractions in pig muscle

The aim of the present experiment was to study the effect of the RN⁻ gene on ultrastructure of white fibres and the proportion of the different protein fractions in Longissimus lumborum muscle of RN⁻ pigs. The ultrastructure of muscle was observed in 4 RN⁻ carrier pigs and 4 rn⁺rn⁺ homozygous pigs by mean of electron microscopy. Protein fractionation and quantification were performed on muscle from a second group of 4 RN⁻ and 4 rn⁺ pigs. No change in the proportions of the different protein compartments was observed. The abnormality of the glycolytic fibres of RN⁻ pigs seems to be rather due to an increase of the glucid concentration in the sarcoplasm, perhaps secondarily to a modified osmolarity in the intracellular medium.     

Optimisation of calcium-dependent protease and cathepsin D assays in ostrich muscle and the effect of chemical and physical dry-curing parameters

The best conditions for the assay of cathepsin D and Ca²⁺-dependent pro tease (CDP) activity in ostrich muscle was established in order to have a simple, rapid and reliable method for its determination. Measurements of A_280nm of TCA-soluble peptides and amino acid digests of casein and haemoglobin were used for measuring proteolytic activity in muscle extracts. The best conditions for the reliable determination of cathepsin D activity were found to be the incubation of an enzyme extract for 1 hr at 55 °C in a reaction mixture containing 0.9% (w/v) haemoglobin in 50 mM sodium formate buffer, pH 3.7. Characterization of the assay system for CDPs, obtained after phenyl-Sepharose chromatography, indicated that proteolytic degradation of casein by CDPs was linear with time up to 30 min at 30 °C and up to 0.1 units of activity. The effect of NaCl, KCl, nitrate, ascorbic acid, phosphate, glucose and sucrose on ostrich muscle CDP and cathepsin D activities has been studied. Salt (NaCl and KCl) acts as a strong inhibitor of proteolytic activity. Sodium and potassium nitrates (in the range 0–1000 mg l⁻¹) affected activity to varying degrees. CDP activity was enhanced by sodium nitrate concentrations below 700 mg l⁻¹ and unchanged by potassium nitrate. Cathepsin D activity was inhibited to some extent by sodium nitrate above 200 mg l⁻¹ and completely by potassium nitrate. Results showed that phosphate is an inhibitor of both activities. High concentrations of ascorbic acid (above 6 g l⁻¹) inhibited cathepsin D activity. Glucose (up to 2g l⁻¹) activated cathepsin D activity and inhibited CDP activity (up to 1 g l⁻¹). Sucrose activated enzyme activities at very low concentrations (1 × 10⁻³ M) and inhibited activities above 1 × 10⁻³ M.     

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.     

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.     

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.     

Effect of the dietary supplementation with vitamin E on colour stability and lipid oxidation in packaged, minced pork

The effect of supplementation of vitamin E (200 W kg⁻¹ feed) in the diet of pigs on colour stability and lipid oxidation in minced pork was studied. Control and enriched diets were provided for the last 12 weeks before slaughter. Half of the samples of minced shoulder meat from control and supplemented pigs were packaged on trays with oxygen-permeable overwraps and half in modified atmosphere packs (initial gas mixture: O₂/CO₂/N₂ = 66/ 27/7). Meats were stored for 10 days at 7 °C in an illuminated retail display cabinet. The meat from vitamin E-supplemented pigs was more resistant to lipid oxidation than was the control meat. Gas packaging appeared to increase lipid oxidation in control meat, whereas lipid oxidation was stable in meat from vitamin E-supplemented pigs. Colour stability for gaspacked meat was comparable for both dietary groups. However, oxygen-permeable overwraps had a negative effect on colour stability in vitamin E-enriched meat. The reason for this is not known. The shelf-life of enriched and control meat was similar. Thus supplementation of pig feeds with vitamin E is recommended if an improved stability against lipid oxidation of (minced) pork is required.     

Macronutrients content of Yellow Glacier Lily and Balsamroot; root vegetables used by indigenous peoples of northwestern North America

The macronutrients in two foods used by indigenous peoples of the British Columbia Plateau region were examined. Yellow Glacier Lily and Balsamroot were commonly harvested, processed and stored in large quantities, up until the last three decades, together with many other plant foods. The macronutrients of the two foods, in which the underground bulbs or roots are utilized, are mainly derived from the carbohydrates. Yellow Glacier Lily bulbs have a high starch content, (770 g kg⁻¹ in fresh bulbs, dry basis), and 57 g kg⁻¹ total dietary fibre. They also contain measurable amounts of simple sugars and fructans before and after cooking. Balsamroot, whose taproots were eaten, is another plant indigenous to the region, but unlike Yellow Glacier Lily it contains negligible amounts of starch. The edible portion of Balsamroot has a high total dietary fibre content (250 g kg⁻¹, dry basis), and high fructan content which is reduced to lower molecular weight sugars after pitcooking. The energy derived from the two foods is very similar on a dry basis ranging from 364 to 395 kcal 100 g⁻¹ in the fresh and pitcooked samples.     

Effect of dietary ractopamine on tenderness and postmortem protein degradation of pork muscle

Twenty-four finishing pigs with a mean starting weight of 82 kg were assigned to two dietary regimens: (1) a corn–soybean meal basal diet (control; n = 12), and (2) the basal diet supplemented with 20 ppm ractopamine HCl (RAC; n = 12). After 28–30 days on the feeding trial, pigs were slaughtered, and the growth and carcass characteristics were measured. Furthermore, the 3rd–13th rib section of longissimus muscle was excised at 48 h postmortem, sliced into 19-mm thick chops, vacuum packaged, stored at 2 °C, and subjected to Warner–Bratzler shear force (WBSF) and electrophoretic tests after 2, 4, 7, 10, 14, and 21 days (postmortem). RAC feeding increased (P < 0.01) pig carcass weight and percent lean, but it also increased the day-2 muscle WBSF by 20% (P < 0.01). The shear force difference between control and RAC pig muscles gradually decreased and vanished by day 10 (P > 0.05) when both muscle groups became more tender. The muscle from RAC-fed pigs exhibited a slower protein degradation rate than muscle from the control animals, notably for proteins in the 15–45 kDa range. The results suggested that the tenderness difference between ractopamine-treated and control pig muscles was related to the proteolysis rate, and could be diminished with adequate postmortem ageing.