Effect of tumbling and RN genotype on sensory perception of cured-smoked pork loin

Effects of tumbling and RN genotype on sensory perception of cured-smoked loins were studied on loins from 32 crossbred female pigs containing Hampshire blood. Right-side loins were intermittently tumbled during 4 h, whereas left-side loins were left non-tumbled. Tumbled loins were more tender and uniform in cured colour as well as less acidulous in taste compared with non-tumbled loins. Further, the formation of undesirable pores was lower in tumbled loins. Final juiciness tended to be higher and meat taste intensity lower in tumbled loins, whereas initial juiciness did not differ. There were no significant interactions between tumbling and RN genotype for sensory attributes. RN⁻ carriers (RN⁻/rn⁺) were more acidulous in taste, had more pronounced meat taste and were saltier than non-carriers (rn⁺ /rn⁺). Moreover, they tended to have higher initial juiciness and more undesirable pores, and be less homogeneous in cured pink colour. No differences in consumer preference between the four treatments were detected in the ranking test, but most persons ranked non-tumbled loins highest regarding overall liking. Instrumental tenderness measurements agreed well with sensory tenderness scores.     

Effect of dietary antioxidant and fatty acid supply on the oxidative stability of fresh and cooked pork

The effect of dietary oil (linseed or soybean oil) and antioxidant treatment (α-tocopheryl acetate (AT; 40ppm) versus a cocktail (AOC; 200ppm): α-tocopheryl acetate+rosemary+citric acid+gallic acid) on colour, lipid and protein oxidation of fresh and processed pork was investigated. No effect of oil source on different parameters of oxidation was seen. No effect of antioxidant treatment on colour stability of fresh longissimus thoracis (LT) or cooked cured ham (CCH) was observed. For both antioxidant treatments, lipid oxidation in fresh LT and CCH was well controlled during display. However, lipid oxidation increased significantly in pre-frozen uncured cooked meat under aerobic conditions. No unambiguous effect of antioxidant treatment on protein oxidation was observed. There seemed to be no clear link between colour, protein and lipid oxidation. At the dose used in this study, no additional or synergistic effects of the extra components of the AOC on the different oxidation parameters was found.     

Effects of genotype and dietary oil supplementation on performance,carcass traits,pork quality and fatty acid composition of backfat and intramuscular fat

A 42-day study was conducted to evaluate the effect of genotype: terminal sire line Duroc × F1 (DC×F1); terminal sire line Embrapa MS-115 × F1 (MS-115×F1); and MS-115 × Moura (MS-115×MO) and three dietary oil sources: soybean; canola; and canola + flax, on performance, carcass traits, pork quality, and fatty acid composition. Genotype affected the technological quality of pork and fatty acid profile. MS-115-sired pigs had better meat color and Duroc-sired pigs had higher intramuscular fat content, more saturated fat and better omega-6/omega-3 ratio. Moura breed influenced positively meat tenderness and intramuscular fat. Diet did not affect the technological quality of the meat. Canola or canola + flax oil diet supplementations increased monounsaturated and C18:3 and decreased C18:2 fatty acids, reducing the omega-6/omega-3 ratio. The best omega-6/omega-3 ratio was obtained through supplementation with canola + flax.     

Interactions between genotype,dietary fat saturation and vitamin A concentration on intramuscular fat content and fatty acid composition in pigs

The effect of dietary fat saturation (dFat) and dietary vitamin A (dVitA) level (0 IU vs. 100,000 IU) on performance, carcass characteristics and fatty acid composition in the offspring of two terminal sires: Duroc (DU) and Landrace × Large White (LD × LW) was studied. In the inner backfat layer, the DU-sired pigs had higher C16:0 proportion (P < 0.05) and tended (P < 0.07) to have higher total saturated fatty acids (SFA) and lower C18:1 n-9 proportions than LD × LW-sired pigs. An interaction sire line × dVitA was observed for intramuscular fat (IMF) content (P < 0.005). The effect of supplementation with the high dVitA level in DU-sired pigs was associated with a 20% increase in IMF while no effect was observed in LD × LW pigs. Fatty acid pattern was affected by dFat and sire line. In the inner backfat layer, LD × LW-sired pigs receiving the low dVitA level increased C18:0 proportions by 8% in comparison to animals receiving the high dVitA, whereas in DU-sired pigs the effect of vitamin A was opposite. It is concluded that the effect of dFat and dVitA concentration on IMF content and fatty acid profile of subcutaneous backfat and IMF is variable according to pig genotype.     

Sensory characteristics of cooked pork loin as affected by nucleotide content and post-mortem meat quality

Muscle longissimus dorsi excised at 2hr post mortem was utilised to study the effect of post-mortem meat quality, and their content of nucleotide metabolites, on the sensory characteristics of cooked loin. Four different post mortem meat qualities were defined: pale soft exudative (PSE), red soft exudative (RSE), red firm non-exudative (RFN) and dark firm dry (DFD). The DFD meat quality class showed low sour and salty tastes and a high sweet taste, low astringency and high juiciness and tenderness, giving the best overall quality. On the other hand, the RSE quality class produced a meat with a low juiciness and high hardness, and a low overall quality although these differences were not significant (p<0.05) against RFN and PSE meats. The effect of nucleotide metabolite contents on the sensory meat properties were most significant on taste although, the different meat qualities were only significantly different (p<0.05) in the content of hypoxanthine, guanosine, GDP and IDP.     

On-line determination of fatty acid composition in intramuscular fat of Iberian pork loin by NIRs with a remote reflectance fibre optic probe

A near infrared spectrometer equipped with a standard 210/210 bundle remote reflectance fibre-optic probe, with a 5×5 cm quartz window type, was used for the determination of fatty acids in the Longissimus dorsi muscle of Iberian breed swine. The fatty acids C14:0, C16:0, C16:1, C17:0, C17:1, C18:0, C18:1, C18:2, C18:3, Σpolyunsaturated, Σmonounsaturated and Σsaturated were determined in samples of intramuscular fat from Iberian breed swine by direct application of the fibre-optic probe onto the loin sample, with no treatment or manipulation of the sample. The regression method employed was modified partial least squares. The calibration results using the fibre-optic probe for 74 loin samples had multiple correlation coefficients (RSQ) for C14:0, C16:0, C16:1, C17:0, C17:1, C18:0, C18:1, C18:2, C18:3, Σpolyunsaturated, Σmonounsaturated and Σsaturated acid of 0.785, 0.798, 0.788, 0.825, 0.762, 0.765, 0.696, 0.859, 0.878, 0.807, 0.943, 0.858, respectively, and standard errors of prediction corrected for the same fatty acids (%) of 0.08, 0.63, 0.26, 0.02, 0.02, 0.51, 0,77, 0.64, 0.05, 1.06, 0.34, 0.70, respectively. The robustness of the method was checked by applying the fibre-optic probe to unknown samples of Iberian breed pork loin in a slaughterhouse, using 15 samples for the external validation.     

坚果中脂肪含量及脂肪酸组成分析

目的分析16种市售坚果中脂肪含量及脂肪酸组成,比较不同品种坚果间脂肪含量、饱和脂肪酸和不饱和脂肪酸组成的差异。方法采用气相色谱分析法测定坚果中37种脂肪酸的含量,用最小显著性差异法(least-significant difference,LSD)法进行多重比较。结果坚果的平均脂肪含量为(55.6±0.86)g/100 g,变化范围为40.2~71.3 g/100 g,碧根果脂肪含量显著高于其他品种坚果脂肪含量(P0.05);坚果中的不饱和脂肪酸含量为72.77~95.47 g/100 g脂肪,平均值为(86.68±0.12)g/100 g脂肪,显著高于饱和脂肪酸4.53~22.19 g/100 g脂肪,平均值为(11.31±0.16)g/100 g脂肪(P0.05),东北榛子中单不饱和脂肪酸总含量最高,为84.34 g/100 g脂肪,而纸皮核桃中的多不饱和脂肪酸总含量最高,为74.17 g/100 g;坚果中不含短链脂肪酸和中链脂肪酸。结论坚果中不饱和脂肪酸含量较多,富含ω-6和ω-3脂肪酸,营养价值较高。     

Determination of fatty acid composition of pork fat by Fourier transform infrared spectroscopy

The fatty acid composition of pork fat determines its processing quality. FTIR spectroscopic methods were evaluated on pork back and breast fat, directly on fat slices and on the fat extracts. Near infrared transmission and middle infrared using an ATR method were developed to determine the fatty acid content in the fat extracts. The results obtained with 80 back and 80 breast samples showed the validity of infrared spectroscopy to estimate SFA (saturated fatty acids), MUFA (monounsaturated fatty acids), PUFA (polyunsaturated fatty acids), C16:0, C18:0, C18:1 and C18:2 contents in fat extracts. Correlation coefficients (R(2)) were around 0.91 and 0.98 for MIR (ATR) and around 0.85 and 0.96 for NIR (transmission). Direct measurements on fat slices by NIR predicted SFA, PUFA, C18:1 and C18:2, although the coefficient correlations were less good; 0.69-0.79. This method though, is easier and faster than other techniques and is accurate enough to discriminate fat samples separated by standard visual and texture classification. Measurements could be made in 1 min.     

Microwave heating of cooked pork patties as a function of fat content

ABSTRACT:  In this study, the parameters heating rate, dielectric factors, and specific heat capacity, which determine the heating profiles and the dissipation of energy during microwave heating, were obtained for precooked pork patties. The pork patties studied were lean meat, pure back fat, and several lean meat/back fat mixtures. Microwave heating at 798 W power was not sufficient to accelerate the heating rates in 100% lean meat compared to 415 W. However, samples were able to heat up faster and dissipate more energy at 798 W power as fat content increased and moisture content decreased. The recorded differences in the specific heat capacity of the studied materials as a function of temperature seemed not to be the key factor to explain the observed temperature rises. Temperature rise seemed to have more to do with the interactions of fat with the electromagnetic field, and with viscosity changes during phase transitions. Trends found for the dielectric properties over microwave heating of meat products agree with data from other authors, but the influence of parameters related to the sample composition and structure should be taken into account. The dissipation factors (ɛ"/ɛ') provided a good approximation to the capacity of the samples containing lean meat and the lean meat/fat mixtures to transform the electromagnetic energy into heat. Neither the dielectric constant nor the loss or dissipation factors were able to clarify the high amount of energy transformed into heat in 100% back fat. Penetration depth and reflected power indicated that back fat allowed microwave energy to be repeatedly redirected to the material.     

Changes in fatty acid content and composition in silage maize during grain filling

BACKGROUND: The stage of maturity at harvest has a major effect on the fatty acid (FA) content and composition of forage plants consumed by dairy cows. The present study investigated the dynamics of FA content and composition in stover (leaves and stem) and ears (cob, shank and husks) of two maize genotypes (G2 and G6) grown on sandy and clay soils and harvested at 14, 42, 56, 70 and 84 days after flowering (DAF). In addition, the FA content and composition of six maize genotypes (G1‐G6) grown on the two soil types were compared at the normal harvest time of early genotypes in the Netherlands (70 DAF). RESULTS: The contents of total FAs and major individual FAs in both stover and ears changed significantly (P < 0.001) during the grain‐filling period (14‐84 DAF). In stover the contents of C16:0, C18:2, C18:3 and total FAs declined (P < 0.001) while those of C18:0 and C18:1 increased (P < 0.001) with progressive grain filling. The rate of decline in C18:3 and total FA contents was slower during 14‐56 DAF as compared with 56‐84 DAF. In ears, the contents of C16:0, C18:1, C18:2 and total FAs increased up to 56 DAF and then remained more or less constant until 84 DAF. At 70 DAF the content of polyunsaturated fatty acids (PUFAs) in both stover and ears did not differ among the six genotypes. However, the average contents of C16:0, C18:3 and total FAs in stover were higher (P < 0.05) on clay soil, whereas those of C18:0 and C18:1 were higher on sandy soil. CONCLUSION: The results demonstrate that the maximum PUFA content in silage maize is harvested around 56 DAF, in the present study at a T_sum of 927 °C.d or at an ear dry matter content of 440 g kg^?1, which is before the onset of rapid senescence. Any further delay in harvesting will cause a rapid decline in C18:3 content in maize silages. Copyright © 2011 Society of Chemical Industry     

Effect of dietary conjugated linoleic acid in combination with monounsaturated fatty acids on the composition and quality traits of cooked loin

Three levels (0%, 1% and 2%) of a conjugated linoleic acid oil (CLA) were combined with two levels of monounsaturated fatty acids (MUFA) (low – 19% average and high – 39% average) for pig feeding (n = 48, eight animals per treatment). The composition and quality traits (fat content, cooking losses, lipid oxidation, fatty acid profile, volatile profile and sensory analysis) of cooked loin, as affected by dietary CLA, MUFA, and CLA × MUFA interaction were studied. CLA and CLA × MUFA did not affect the intramuscular fat content, cooking losses, lipid oxidation, volatile profile and sensory traits of cooked meat. Therefore, CLA could be supplemented to the pig diet without detriment of the measured quality traits of cooked meat, and regardless of the MUFA level of pig diets. Dietary CLA increased the content of SFA and decreased the level of MUFA of meat, and led to a CLA enrichment, regardless the MUFA level of pig diets, but the content of CLA isomers of fresh meat decreased after the cooking process.     

Effects of replacing maize silage with lucerne silage and lucerne silage chop length on rumen function and milk fatty acid composition

The objective of this study was to investigate whether higher lucerne (Medicago sativa; alfalfa) silage inclusion rate and longer lucerne chop length improves rumen function through increased provision of physically effective fiber, when included in a maize and lucerne silage-based total mixed ration. Diets were formulated to contain a 50:50 forage:concentrate ratio [dry matter (DM) basis] and be isonitrogenous and contain equal levels of neutral detergent fiber (320 g/kg). The forage portion of the offered diets was composed of maize and lucerne silage DM in proportions (wt/wt) of either 25:75 (high lucerne; HL) or 75:25 (low lucerne; LL). Second-cut lucerne was harvested and conserved as silage at either a long (L) or a short (S) chop length (geometric mean particle lengths of 9.0 and 14.3 mm, respectively). These variables were combined in a 2 × 2 factorial arrangement to give 4 treatments (HLL, HLS, LLL, LLS), which were fed in a 4 × 4 Latin square design study to 4 rumen-cannulated, multiparous, Holstein dairy cows in mid lactation. Effects on DM intake, chewing behavior, rumen volatile fatty acid concentration, rumen pH, rumen and fecal particle size, milk production, and milk fatty acid profile were measured. Longer chop length increased rumination times per kilogram of DM intake (+2.8 min/kg) relative to the S chop length, with HLL diets resulting in the most rumination chews. Rumen concentrations of total volatile fatty acids, acetate, and n-valerate were higher for the HLS diet than the other 3 diets, whereas rumen propionate concentration was lowest for the HLL diet. Physically effective fiber (particles >4 mm) percentage in the rumen mat was increased when L chop length was fed regardless of lucerne inclusion rate. No effect of treatment was observed for milk yield, although milk protein concentration was increased by L for the LL diet (+1.6 g/kg) and decreased by L for the HLL diet (?1.4 g/kg). Milk fat concentrations of total cis-18:1 (+3.7 g/100 g of fatty acids) and 18:3 n-3 (+0.2 g/100 g of fatty acids) were greater with HL. In conclusion, longer lucerne silage chop length increased time spent ruminating per kilogram of DM intake, but had no effect on rumen pH in the present study. Increasing dietary lucerne inclusion rate had no effects on rumination activity or rumen pH, but decreased the ratio of n-6:n-3 polyunsaturated fatty acid concentrations in milk fat.     

不同加工方式与时间对猪肉脂肪含量和脂肪酸组成的影响

为研究不同加工方式和时间对猪肉脂肪酸组成、脂肪含量、营养及风味的影响,以PIC猪背最长肌为原料,经不同时间的蒸煮或烤制加工后,分别测定各样品的脂肪含量和脂肪酸组成。结果显示,加工时间主要影响PUFA/SFA和SFA+MUFA值、磷脂的含量和脂肪酸组成、肌内总脂肪酸的组成;加工方式主要影响肌内脂肪总含量、甘三酯的含量、游离脂肪的脂肪酸组成;游离脂肪酸的含量同时受加工时间和方式的影响,而甘三酯的脂肪酸组成在加工中没有明显变化。因此采用不同时间的蒸煮或烤制加工时,加工方式和时间都会对猪肉脂肪酸组成、脂肪含量、营养及风味产生影响,但加工时间对脂肪酸组成、营养和风味的影响更大,而加工方式对脂肪含量的影响更显著。     

肌内脂肪与背最长肌肉质、脂肪酸组成的关系

研究肌内脂肪（IMF）含量与肉质以及脂肪酸含量和组成比例之间的关系。以北京黑猪背最长肌（n=20）为实验材料,测定肌内脂肪含量、肉质以及脂肪酸含量和组成。结果显示,肌内脂肪含量与滴水损失呈显著正相关（p<0.05）,与蒸煮损失、剪切力、肉色的相关性不显著（p>0.05）。随着肌内脂肪含量升高,除长链多不饱和脂肪酸(C_20:3n6、C_20:4n6)以外的大多数脂肪酸含量增加,相对比例也上升;多不饱和脂肪酸的含量增加,但是相对比例下降;长链多不饱和脂肪酸的含量和相对比例都降低。随着肌内脂肪含量的升高,饱和脂肪酸（SFA）和单不饱和脂肪酸（MUFA）的含量升高,回归方程斜率分别为197.3和248.31,多不饱和脂肪酸（PUFA）增加的幅度不大,回归方程的斜率为11.43。结果提示:肌内脂肪含量较低时（本实验平均值2.86%）,对肉质的影响不显著。随着肌内脂肪含量升高,总脂肪酸含量（TFA）增加,主要归因于SFA和MUFA含量的增加。PUFA的含量相对稳定,受肌内脂肪含量变化的影响较小。      

The influence of RN genotype, including the new V199I allele, on the eating quality of pork loin

The eating quality of M. longissimus dorsi (LD) from RN⁻ homozygotes, RN⁻ heterozygotes and RN⁻ non-carriers was investigated in a Swedish Hampshire×Finnish Landrace pig population. The recently identified new allele (V199I, here denoted rn*) at the RN locus was also detected among the pigs selected and included in the sensory evaluation. The number of animals varied from 10 to 15 in the five genotype groups; RN⁻/RN⁻, RN⁻/rn+, RN⁻/rn*, rn+/rn+ and rn+/rn* (in total 59 pigs). In addition, one pig was determined to be rn*/rn* but was excluded from the analysis. The three genotypes in which the RN⁻ allele was represented (RN⁻/RN⁻, RN⁻/rn+ and RN⁻/rn*) had higher glycogen and lower protein contents as well as lower ultimate pH (measured 48 h post-mortem) in LD than the non-carriers (rn+/rn+ and rn+rn*). Of the sensory parameters evaluated (tenderness, chewing time, chewing residual, juiciness, meat flavour and acidity), the five RN genotypes only affected acidity significantly; the RN⁻ allele contributing to a more acid taste in LD. The influence of the rn* allele resembled that of rn+ on the sensory parameters. When the material was divided into three groups (homozygous, heterozygous and non-carriers of the RN⁻ allele) the juiciness was found to be significantly influenced by RN genotype, and LD from animals that were homozygous and heterozygous with respect to the RN⁻ allele exhibited a higher juiciness than LD from non-carriers. The RN⁻ allele also tended to contribute to greater tenderness, which was significantly higher in LD from heterozygous carriers than from non-carriers of the RN⁻ allele. A more rapid decline in pH (measured as pH at 45 min and 3 h post-mortem) contributed to a greater tenderness in LD (according to a trained panel and Warner-Bratzler shear force). In addition to the RN genotype, the decline in pH was influenced by carcass weight, which varied between 71 and 97 kg, and by stunning procedure, which changed during the course of the study from individual to group stunning with CO₂. The individual stunning procedure contributed to a lower pH in the initial post-mortem phase (pH₄₅), whereas a higher carcass weight and the RN⁻ allele lowered the pH in the mid-post-mortem region (pH_3h and pH_24h), significantly (P0.05). The pH continued to decline after 24 h post-mortem and the ultimate pH was not reached until 48 h post-mortem. The cooking loss, juiciness and acidity were related to the specific characteristics of the RN⁻ carriers, such as higher glycogen content, lower protein content and lower ultimate pH (pH_48h).     

Effects of soybean oil and linseed oil on fatty acid compositions of muscle lipids and cooked pork flavour

This study was conducted to investigate the effects of dietary oil on the fatty acid compositions of the longissimus and biceps brachii muscles and its effects on cooked muscles flavour. Seventy-two crossbred barrows (Duroc×Landrace×Large White), were blocked by weight and randomly assigned to one of three treatments. The three dietary treatments were: (a) no oil supplement (CON); (b) 3% soybean oil supplement (SO3); (c) 3% linseed oil supplement (LO3). Dietary linseed oil and soybean oil significantly increased the contents of C18:3 and C18:2 in the neutral lipids and phospholipids in both longissimus muscle and biceps brachii muscle, respectively. Aroma compounds analysis indicated only few aroma compounds were affected significantly by dietary oil in both cooked longissimus muscle and biceps brachii muscle. The flavour attributes of cooked longissimus muscle and biceps brachii muscle were not influenced by feeding 3% soybean oil. Feeding 3% linseed oil did not deleteriously affect the flavour of cooked longissimus muscle but cooked biceps brachii muscle from LO3 had significantly lower pork flavour and higher abnormal flavour than CON and SO3.     

泡酒肥肉浸制过程中脂肪氧化和脂肪酸组成的变化

泡酒肥肉是豉香型白酒(玉冰烧)生产过程\     

Fatty acid composition and oxidative susceptibility of fresh loin and liver from pigs fed conjugated linoleic acid in combination with monounsaturated fatty acids

Three levels (0%, 1% and 2%) of conjugated linoleic acid (CLA) were combined with two levels of monounsaturated fatty acids (MUFA) (low: 19% and high: 39%) for pig feeding. The fatty acid profile of neutral lipids (NL) and polar lipids (PL) of loin and liver and their oxidative susceptibility were studied. A dose-dependent enrichment in cis-9, trans-11 CLA and trans-10, cis-12 CLA in NL and PL of loin and liver was obtained. This effect was independent of the MUFA supplementation (except for NL of loin in which the CLA accumulation was higher at high MUFA levels). Regardless of the MUFA supplementation, dietary CLA increased the ratio of saturated fatty acids (SFA) to unsaturated fatty acids in both tissues and lipid fractions. The interaction between CLA and MUFA affected the SFA and polyunsaturated fatty acids contents of PL from loin. Regardless of the MUFA level of the diets, CLA supplementation decreased the induced peroxidation values in liver and did not change those of loin.     

Correlations of trained panel sensory values of cooked pork with fatty acid composition,muscle fiber type,and pork quality characteristics in Berkshire pigs

The objective was to examine the relationship of trained panel sensory scores of cooked pork with fatty acid composition, muscle fiber type, and meat quality characteristics from Berkshire pigs. No or few associations were found between the panel sensory scores of cooked meat, especially tenderness attributes, and fatty acid composition; however, intramuscular fat content positively correlated with off-flavor score (r = 0.31). On the other hand, the morphological characteristics of muscle fibers were correlated with panel sensory values. Muscles with smaller cross-sectional area and higher density of fibers were more closely associated with softer, more tender panel scores and a lower number of chews than muscles with larger fiber area and lower density of fibers. The water holding capacity test of filter-paper fluid uptake was moderately correlated with panel scores of softness (r = 0.33), initial tenderness (r = 0.38), chewiness (r = 0.40), juiciness (r = − 0.27), flavor intensity (r = − 0.23), and off-flavor (r = 0.30). Panel sensory values of Berkshire pig meat was moderately related to postmortem meat quality, especially water holding capacity. A more thorough understanding of the relationships between fatty acid composition and muscle fiber type with palatability is needed.