Effects of high pressure treatment and temperature on lipid oxidation and fatty acid composition of yak (Poephagus grunniens) body fat

Effects of high-pressure treatment (100 MPa to 600 MPa) on lipid oxidation and composition of fatty acids in yak body fat at 4 °C and 15 °C were investigated for up to 20 days storage. 400 and 600 MPa treatments increase the level of thiobarbituric acid-reactive substances (TBARS) 335% and 400% (p < 0.05), respectively. Composition analysis shows that 600 MPa treatment induces a lower (p < 0.05) percentage of polyunsaturated fatty acids, and C22:6 decreased significantly. A significant decrease in PUFA/SFA and n-6/n-3 PUFA values was observed at the end of storage. Samples treated at the lower pressures gave good sensory acceptability. It is concluded that a higher-pressure treatment is important in catalyzing lipid oxidation and the evolution of fatty acids in pressure-treated yak body fat.     

Effect of high pressure processing and cooking treatment on the quality of Atlantic salmon

The effect of high pressure treatment (HPP) (150 MPa and 300 MPa for 15 min) and cooking on quality of Atlantic salmon based on microbial activity, lipid oxidation, fatty acid profile, colour and texture during 6 days of storage was studied. High pressure and cooking significantly (p < 0.05) reduced microbial growth. The 300 MPa treatment and cooking showed higher L∗ and b∗ values but lower a∗ values for dark muscle compared to control and samples treated at 150 MPa. An increase in pressure resulted in an increase in hardness, gumminess and chewiness parameters, and a decrease in adhesiveness compared to control and cooked samples. Whereas cooking and 150 MPa led to similar oxidation development as control in dark muscle, the 300 MPa treatment effectively reduced the samples susceptibility to oxidation. Fatty acid profile of cooked Atlantic salmon dark muscle showed significantly (p < 0.05) lower amounts of total saturated, n−3 Polyunsaturated fatty acids (PUFA) and n−6 PUFA and significantly (p < 0.05) higher amounts of monoenes than HPP treated samples during the entire storage period. However, the most important finding of this study was that there was no significant (p > 0.05) difference between control and HPP treated samples in terms of total saturated, monoenes, n−3 PUFA and n−6 PUFA fatty acid profile. This demonstrates that HPP is a very mild process in terms of its effect on fatty acids.     

High pressure induced changes in beef muscle proteome: Correlation with quality parameters

The relationship between pressure induced changes on individual proteins and selected quality parameters in bovine longissimus thoracis et lumborum (LTL) muscle was studied. Pressures ranging from 200 to 600 MPa at 20 °C were used. High pressure processing (HPP) at pressures above 200 MPa induced strong modifications of protein solubility, meat colour and water holding capacity (WHC). The protein profiles of non-treated and pressure treated meat were observed using two dimensional electrophoresis. Proteins showing significant differences in abundance among treatments were identified by mass spectrometry. Pressure levels above 200 MPa strongly modified bovine LTL proteome with main effects being insolubilisation of sarcoplasmic proteins and solubilisation of myofibrillar proteins. Sarcoplasmic proteins were more susceptible to HPP effects than myofibrillar. Individual protein changes were significantly correlated with protein solubility, L*, b* and WHC, providing further insights into the mechanistic processes underlying HPP influence on quality and providing the basis for the future development of protein markers to assess the quality of processed meats.     

High pressure induced changes on sarcoplasmic protein fraction and quality indicators

The combined effect of pressure and mild temperature treatments on bovine sarcoplasmic proteins and quality parameters was assessed. M. longissimus dorsi samples were pressurised in a range of 200–600 MPa and 10–30 °C. High Pressure Processing (HPP) induced a reduction of protein solubility (p < 0.001) compared to non-treated controls (NT), more pronounced above 200 MPa. HPP at pressures higher than 200 MPa induced a strong modification (p < 0.001) of meat colour and a reduction of water holding capacity (WHC). SDS–PAGE analysis demonstrated that HPP significantly modified the composition of the sarcoplasmic protein fraction. The pressurisation temperature mainly affected protein solubility and colour; a smaller effect was observed on protein profiles. Significant correlations (p < 0.001) between sarcoplasmic protein solubility and both expressible moisture (r = −0.78) and colour parameters (r = −0.81 to −0.91) suggest that pressure induced denaturation of sarcoplasmic proteins could influence to some extent WHC and colour modifications of beef. Changes in protein band intensities were also significantly correlated with protein solubility, meat lightness and expressible moisture. These results describe the changes induced by HPP on sarcoplasmic proteins and confirm a relationship between modification of the sarcoplasmic protein fraction and alteration of meat quality characteristics.     

Effect of feeding growing–fattening rabbits a diet supplemented with whole white lupin (Lupinus albus cv. Amiga) seeds on fatty acid composition and indexes related to human health in hind leg meat and perirenal fat

A total of 20 weaned rabbits (33 days old) (10 per treatment) were fed one of two diets that included 150 g of sunflower meal (SF)/kg of diet or 120 g of whole white lupin (WL)/kg of diet for 42 days. The WL diet contained less saturated fatty acids (SFA) and polyunsaturated fatty acids (PUFA) but more monounsaturated fatty acids (MUFA) than the SF diet. The WL diet significantly decreased SFA and PUFA content, as well as the PUFA n − 6/PUFA n − 3 ratio and saturation, atherogenic and thrombogenic indexes in hind leg meat. The fatty acid composition in perirenal fat was similar to that of hind leg meat; however, significantly higher MUFA levels were observed in rabbits fed the WL diet. Thus, feeding rabbits the WL diet affected the fatty acid profile of hind leg meat and perirenal fat in a favourable manner.     

Effect of high-pressure treatment on the fatty acid composition of intramuscular lipid in pork

To investigate the effect of high-pressure (HP) treatment on lipid oxidation and fatty acid composition of intramuscular lipid in pork, the longissimus muscles from Rongchang (RC) pig were pressurized at 200, 350 and 500 MPa for 20 min at 20 °C prior to 7 days storage at 4 °C. The changes in TBARS number, lipid content and fatty acid composition of total intramuscular lipids, phospholipids, triglycerides and free fatty acids in untreated and HP treated samples were analyzed. HP treatment had no significant effect on the content and fatty acid composition of total lipids and triglycerides in the samples, but treatment at 350 MPa and above led to marked increases in TBARS values and lipolysis of partial phospholipids causing a correlative increase of free fatty acid content. A preferential hydrolysis for polyunsaturated fatty acids (PUFA) in phospholipids was observed, which resulted in the percentage of PUFA in phospholipids decreasing markedly and thereby that in free fatty acids increasing significantly.     

Fatty acid composition of minced meat,longissimus muscle and omental fat from Small East African goats finished on different levels of concentrate supplementation

Effects of supplementing Small East African (SEA) goats with concentrate diets on fatty acids composition of minced meat, M. longissimus dorsi (LD) and omental fat were assessed using 23 animals (14.5 months old and 20.1 kg body weight). Goats were subjected to four levels of concentrate supplementation: ad libitum concentrate allowance (T100), 66% (T66), 33% (T33) and 0% (T0) of ad libitum concentrate allowance. All goats were slaughtered after 90 days of experimental period. Minced meat from concentrate-supplemented goats had higher (P < 0.05) proportions of unsaturated fatty acids (UFA), monounsaturated fatty acids (MUFA) and desirable fatty acid (DFA) than that of non-supplemented ones (T0). Minced meat from T00 and T66 goats had similar proportions of polyunsaturated fatty acids (PUFA) and n-6 PUFA that were higher (P < 0.05) than that of other dietary groups. There was limited variation in fatty acids composition of LD attributable to concentrate supplementation. Trans-vaccenic and linoleic acids were in higher (P < 0.05) proportion in omental fat from concentrate-supplemented goats whereas margaric and arachidonic acids were in higher (P < 0.05) proportion in omental fat from non-supplemented goats. Overall, LD was associated with PUFA, omental fat with saturated fatty acids (SFA), minced meat with MUFA. It is concluded that finishing SEA goats on concentrate diets will increase the proportion of DFA in meat from them. In addition, the proportion of PUFA in meat from such goats will peak at concentrate supplementation equivalent to 66% of their ad libitum intake. Consumers should avoid high intake of internal fat due to their richness in SFA.     

Colour,lipid and protein stability of Rhea americana meat during air- and vacuum-packaged storage: Influence of muscle on oxidative processes

Physicochemical characteristics and oxidative stability during storage were determined in Gastrocnemius pars interna (GN) and Iliofiburalis (IF) muscles of Rhea americana. Glycolytic potential (GP) and pH decline of muscles were measured within the first 24 h post mortem. Colour, lipid and protein stability were determined during storage of meat, i.e. 5 days under air-packaging at 4 °C, or 28 days under vacuum-packaging at 4 °C. In parallel, anti-oxidant status of muscles was estimated by measuring α-tocopherol content and anti-oxidant enzyme activities (superoxide dismutase and catalase), while pro-oxidant status was evaluated by determining haeminic iron and long chain fatty acids (especially polyunsaturated fatty acids). The ultimate pH was similar in both muscles, but the GP value was significantly higher in IF than in GN muscle. Haeminic iron and alpha-tocopherol content differed between muscles, with 30% more haeminic iron (p < 0.05) and 134% more alpha-tocopherol (p < 0.001) in IF than GN muscle. The IF muscle presented higher lipid content and lower PUFA/SFA ratio (polyunsaturated fatty acids/saturated fatty acids) than GN muscle. With storage under air-packaging, lipid and protein oxidation of rhea muscles increased up to 275% and 30%, respectively. This increase was more rapidly and marked in IF muscle. The IF also showed high level of metmyoglobin accumulation after 3 days of storage (47%) and was rejected by 1 consumer out of 2 in sensorial analysis. Under vacuum-packaging, both muscles showed a high stability of colour and no oxidation of lipids and proteins.     

Salt effect on heat-induced physical and chemical changes of salmon fillet (O. gorbuscha)

This research studied the effect of salt on kinetics for quality changes in pink salmon fillet, during commercial sterilisation. Sample cuts from salmon fillets were placed in sealed aluminum containers and heated at 121.1 °C for 10, 30 and 60 min. Samples with 1.5% (w/w) salt addition were compared with those without added salt. Salt addition reduced cook loss, area shrinkage and shear force of the heated fillet and resulted in a slightly darker colour. Effect of salt addition in thiamin loss, degree of lipid oxidation and fatty acid profile was not significant. Peroxide (PV) and thiobarbituric acid (TBA) values slightly increased within the first 10 min of heating, followed by a significant reduction as heating progressed. No measurable loss of polyunsaturated fatty acids (PUFA) was observed. Thermally processed shelf-stable salmon investigated should be a valuable source of ω-3 PUFA, with EPA values ranging from 52 to 71 mg/100 g product and DHA ranging from 258 to 340 mg/100 g of product.     

Influence of HPP conditions on selected beef quality attributes and their stability during chilled storage

The aim of this work was to determine the effects of combined pressure and temperature treatments on beef quality attributes after processing and during chilled storage. Beef M. pectoralis profundus samples were pressurised at 400 and 600 MPa at 35, 45 and 55°C and compared with non-treated (NT) and oven cooked samples. High pressure processing (HPP) at higher temperatures (55°C) resulted in lower Warner Bratzler Shear Force (WBSF) and cook loss values than processing at 35°C. Thiobarbituric acid reactive substances (TBARS) values of pressurised samples were lower than cooked samples after processing and throughout refrigerated storage. An increase (p<0.001) in the omega 6/omega 3 (n6/n3) fatty acid ratio was found when pressure-temperature treatments were compared to raw samples, however, oven cooked samples presented the highest n6/n3 ratio among all of the treatments examined. The reported results show that HPP alters meat quality to a lesser extent than conventional cooking, thereby minimising the processing impact.     

Effect of high pressure on moisture and NaCl diffusion into turkey breast

High-pressure processing (HPP) affects food component diffusion. This study evaluated pressure (0.1-300 MPa) effect on the diffusion of NaCl and water into turkey breast at 25 °C. NaCl and water diffusion were found to be a function of pressure and holding time. During the pressure come-up-time, diffusion of water and NaCl into the sample was enhanced as compared to control. The diffusion coefficient of moisture infusing out of the sample was found to be a minimum at 150 MPa. The diffusion coefficient of NaCl infusing into the sample was maximum at 150 MPa. Within the range of experimental conditions studied, 150 MPa treatment (up to 15 min holding time) yielded meat samples with minimum hardness, gumminess, and chewiness. Ultrastructure images revealed that 150 MPa treatments caused swelling of myofibrils, disappearance of the M-line, reduced difference in the density of the A-band and I-band and breaking of segments of Z-line. HPP could be a useful technique for the salting of turkey meat.     

Kinetics of the formation of radicals in meat during high pressure processing

The kinetics of the formation of radicals in meat by high pressure processing (HPP) has been described for the first time. A threshold for the radicals to form at 400 MPa at 25 °C and at 500 MPa at 5 °C has been found. Above this threshold, an increased formation of radicals was observed with increasing pressure (400–800 MPa), temperature (5–40 °C) and time (0–60 min). The volume of activation (ΔV^#) was found to have the value −17 ml mol⁻¹. The energy of activation (E_a) was calculated to be 25–29 kJ mol⁻¹ within the pressure range (500–800 MPa) indicating high independence on the temperature at high pressures whereas the reaction was strongly dependent at atmospheric pressure (E_a = 181 kJ mol⁻¹). According to the effect of the processing conditions on the reaction rate, three groups of increasing order of radical formation were established: (1) 55 °C at 0.1 MPa, (2) 500 and 600 MPa at 25 °C and 65 °C at 0.1 MPa, and (3) 700 MPa at 25 °C and 75 °C at 0.1 MPa. The implication of the formation of radicals as initiators of lipid oxidation under HPP is discussed.     

Meat quality parameters of descendants by grading hybridization of Boer goat and Guanzhong Dairy goat

Chemical composition, cholesterol levels, fatty acid profile, meat taste, and quality parameters were evaluated in 48 buck kids from goats of the Guanzhong Dairy breed (Group G) and their crosses (Group F1: 1/2 Boer♂ × 1/2 Guanzhong Dairy♀; Group F2: 3/4 Boer♂ × 1/4 Guanzhong Dairy♀; Group F3: 7/8 Boer♂ × 1/8 Guanzhong Dairy♀) at different ages of slaughter (6, 8 and 10 months). Results indicated that grading hybridization (P < 0.05) affected meat nutritive value. The muscle of hybrid goats had lower crude fat and cholesterol, higher crude protein, and greater proportion of C18:2 and C18:3 than that of Group G at each age. Group F1 goats had better (P < 0.05) desirable fatty acid (DFA) and polyunsaturated fatty acid (PUFA) to saturated fatty acid (SFA) ratios and greater (C18:0 + C18:1/C16:0) ratios (P < 0.01) than those of the other genotypes. Furthermore, the muscles of hybrid goats were tenderer and juicier compared to Group G. In all four groups, cholesterol levels increased (P < 0.01), muscle color became redder (P < 0.05) and tenderness decreased (P < 0.05) with increasing age. The low level of lipids and cholesterol, good meat quality, and the higher ratio of unsaturated to SFA in Group F1 indicate better quality for human consumption.     

Oxidation stability of the lipid fraction in milk powder formulas

The purpose of this study was to predict the shelf life of distinct milk powder formulas by measuring hydroperoxides, headspace volatile compounds (propanal, pentanal and hexanal), fatty acid content, and sensory quality. The oxidation stability of three formulas was followed over 15 months of storage at 25 and 37 °C. These formulas were a non-supplemented formula (NSF), and two formulas supplemented with n − 3 and n − 6 long-chain polyunsaturated fatty acids, a formula with 0.83 and 0.47% (SFA), and one with 27.8 and 3.51% of n − 3 and n − 6 long-chain polyunsaturated fatty acids (SFB), respectively. Relative stability decreased in the order NSF at 25 °C > SFA at 25 °C ? SFA at 37 °C ? SFB at 25 °C > SFB at 37 °C. Therefore, we conclude that the polyunsaturated fatty acid content, storage temperature and storage time are very important factors for determining the oxidation stability.     

Effect of crossbreeding and gender on meat quality and fatty acid composition in pork

This study considers the effect of crossbreeding and gender (barrows; gilts) on meat quality and intramuscular and subcutaneous fatty acid composition in pork. The sire lines included Large White (LW), Duroc (D) and Pietrain (P) and the dam line was Landrace (LR)×LW, producing LW×(LR×LW), D×(LR×LW) and P×(LR×LW). Pork samples were removed from Longissimus dorsi (LD) and Semimembranosus (SM) muscles and subcutaneous fat (SCF). There were no important differences in meat quality parameters but D×(LR×LW) had the highest percentage of intramuscular fat. Castrated males had more intramuscular fat and more intense meat colour than female pigs. The Large White and Duroc sire line had saturated fatty acids (SFA) in SM, whereas the Pietrain sire line was significantly higher than Duroc sire line in the concentration of polyunsaturated fatty acids (PUFA), PUFA/SFA (P/S) and the n-6/n-3 ratio. The concentrations of SFA and monounsaturated fatty acids (MUFA) in SCF were significantly higher in LW×(LR×LW) and P×(LR×LW), respectively. No differences were found in the percentage of PUFA, P/S and n-6/n-3 ratio between D×(LR×LW) and P×(LR×LW). Female pigs had the most polyunsaturated intramuscular and subcutaneous fat. The results demonstrate small differences in fatty acid compositions among sires.     

Influence of the type of forage supplied to ewes in pre- and post-partum periods on the meat fatty acids of suckling lambs

The aim of this study was to evaluate the use of forage diets (grazing vs. hay) around the time of ewe parturition, on the fatty acids profile of suckling lamb meat (10-12 kg body weight). Forty-eight multiparous single-bearing ewes were used. The experimental treatments were conducted during the last 5 weeks of pregnancy and the 5 weeks of lactation in a 2 × 2 factorial design. Ewes were fed ad libitum on pastures or hay in the autumn. Results showed that milk from grazing ewes during the pre-partum period had a higher content of PUFA and CLA (P < 0.05) and VA, CLA in their suckling lambs' meat (P < 0.05). The effect in post-partum feeding was greater, revealing higher CLA, PUFA/SFA, PUFA n-3 and PUFA n-6/n-3 in milk and meat (P < 0.05). The CLA, VA and PUFA n-6/n-3 ratios are those that are most affected by grazing. Pre-partum grazing, regardless of post-partum feeding, improves FA composition, increasing CLA content in both milk and meat.     

Carcass and meat quality characteristics and fatty acid composition of tissues from Pietrain-crossed barrows and gilts fed an elevated monounsaturated fat diet

Fifty-one (Landrace∗Large White)∗Pietrain barrows and gilts were used to compare the effect of a diet rich in oleic acid (HO) by feeding a by-product of the olive industry (Greedy-Grass OLIVA®: 1.4% growing, 3.8% finishing) or a grain and soy diet (CONTROL) on carcass characteristics, meat quality and fatty acid profile of intramuscular and subcutaneous fat. Gilts had leaner (P < 0.05) carcasses with lower fat percentage in major primal cuts, and less (P < 0.05) saturated fat compared with barrows with no interaction (P > 0.05) between dietary treatment and gender. Source of dietary fat had no effect (P > 0.05) on primal cut yields, composition of major primal cuts, or carcass and meat quality characteristics. Intramuscular fat from HO fed pigs had higher (P < 0.05) percentage of saturated (SFA) and monounsaturated (MUFA) fatty acids, and lower (P < 0.05) polyunsaturated fatty acids (PUFA) and n-6:n-3 ratio compared with CONTROL animals (37.4% vs. 36.8%, 44.7% vs. 40.1%, 17.9% vs. 23.2%, and 18.9 vs. 21.8 ratio, respectively). Subcutaneous fat from pigs fed HO had greater (P < 0.05) MUFA percentage, lower (P < 0.05) SFA and PUFA percentage, and lower (P < 0.05) n-6:n-3 ratio than pigs fed CONTROL diet (51.4% vs. 48.0%, 30.5% vs. 32.9%, 18.1% vs. 20.1%, and 9.83 vs. 11.3 ratio, respectively). Intramuscular fat had higher proportion of SFA and lower of MUFA showing a higher degree of tissue saturation compared with subcutaneous fat. Feeding Greedy-Grass increased MUFA and decreased PUFA proportions in fat depots reducing the risk of production of carcasses that are soft and oily which result in lower technological and processing quality.     

Use of high pressure to reduce cook loss and improve texture of low-salt beef sausage batters

Methods were investigated to reduce the salt content of beef-containing smallgoods as high-salt intake has been identified as a public health risk for most individuals. Raw meat batters were manufactured from retail beef mince (4–7% fat) using various NaCl concentrations (0–2%), and were packed into casings and subjected to high pressure processing (up to 400 MPa for 2 min at 10 °C). Following pressure treatment, samples were cooked to an internal temperature of 72 °C and cooled. Cooked products were assessed for cooking loss, colour and physical consistency by texture profile analysis. Flavour and overall acceptability were assessed by sensory panels. High pressure processing (HPP) was found to produce a dramatic improvement in the moisture retention of the cooked products. Control (unpressurised) sausages containing 2% NaCl had a similar cook loss (9.3%) to pressure-treated sausages containing just 1% NaCl, whereas unpressurised samples with 1% NaCl had a cook loss of 24.9%. The hardness and gumminess of pressure-treated samples was higher compared to untreated samples, at all salt concentrations. The greatest differences in texture with pressure treatment were seen in the 1% NaCl samples. Pressure treatment generally caused no changes in the colour of either the raw or cooked product; however there was a slight increase in “whiteness” with pressure treatment. Sensory panels reported a greater acceptability in both appearance and texture of pressure-treated sausages of lower salt content compared with non-pressure-treated samples. Examination of extracted proteins using SDS-PAGE and of muscle proteins by thermal analysis indicated that pressure contributed to enhanced binding through protein solubilisation and gelation through partial protein unfolding. The application of high pressure to beef sausages with low-salt content resulted in reduced cooking losses and improved texture.

Industrial relevance

Enhanced meat binding through extraction of salt-soluble proteins is an essential step in the formulation of meat products such as sausages and emulsion-type products. The ability to reduce salt and achieve high binding and water retention through use of HPP is important in being able to produce healthier foods.     

Fatty acid profiles in meat from Caiman yacare (Caiman crocodilus yacare) raised in the wild or in captivity

Chemical composition and fatty acid profiles were determined in Caiman yacare meat originating from the neck and tail cuts of animals raised in the wild (n = 6) or in captivity (n = 6), slaughtered at a live weight of approximately 6 kg. All experimental methods were approved by the appropriate environmental protection agencies. Most chemical components were affected by the origin-cut interaction, with the tail cut of wild animals having the highest amount of intramuscular fat (19.2% of DM) and the lowest of moisture (71.8%) and protein (77.0% of DM). Yacare meat had low amounts of SFA (35.1%), which were similar (P > 0.05) in the cuts and origins studied. The total amount of PUFA was higher (P < 0.05) in wild (31.0%) than in captive animals (23.6%), and n − 3 fatty acids had means of about 5% and 2% for the same groups, respectively (P < 0.05). In general, the FA profile of intramuscular fat in yacare meat had a desirable PUFA/SFA ratio above 0.4.     

Effects of replacing pork backfat with emulsified vegetable oil on fatty acid composition and quality of UK-style sausages

Rapeseed and sunflower oil were used to replace pork backfat in UK-style sausages by incorporating the oils as pre-formed emulsions. Replacing the pork backfat emulsion with rapeseed emulsion at total fat content of about 12%, reduced total saturated fatty acid (SFA) composition from 38% to 14% (4.5 to 1.8 g/100 g), increased monounsaturated fatty acid (MUFA) composition from 45% to 59% and increased polyunsaturated fatty acid (PUFA) composition from 15% to 25%. Partial replacement of pork backfat with rapeseed at a fat content of about 20% reduced SFA from 38% to 24% (7.2 to 4.8 g/100 g). There were no significant differences in eating quality and overall liking other than slight differences in the attributes ‘firmness’ and ‘particle size’. Improvement in the fatty acid composition was achieved without adversely affecting colour shelf life or lipid oxidation. The study suggests that a substantial reduction in SFA can be achieved by incorporating ‘healthy’ oils in UK-style sausages without adversely affecting eating quality or shelf life.