Authentication of farmed and wild turbot (Psetta maxima) by fatty acid and isotopic analyses combined with chemometrics

Fatty acid composition and stable isotope ratios of carbon (delta(13)C) and nitrogen (delta(15)N) were determined in muscle tissue of turbot (Psetta maxima). The multivariate analysis of the data was performed to evaluate their utility in discriminating wild and farmed fish. Wild (n=30) and farmed (n=30) turbot of different geographical origins (Denmark, The Netherlands, and Spain) were sampled from March 2006 to February 2007. The application of linear discriminant analysis (LDA) and soft independent modeling of class analogy (SIMCA) to analytical data demonstrated the combination of fatty acids and isotopic measurements to be a promising method to discriminate between wild and farmed fish and between wild fish of different geographical origin. In particular, IRMS (Isotope Ratio Mass Spectrometry) alone did not permit us to separate completely farmed from wild samples, resulting in some overlaps between Danish wild and Spanish farmed turbot. On the other hand, fatty acids alone differentiated between farmed and wild samples by 18:2n-6 but were not able to distinguish between the two groups of wild turbot. When applying LDA isotope ratios, 18:2n-6, 18:3n-3, and 20:4n-6 fatty acids were decisive to distinguish farmed from wild turbot of different geographical origin, while delta(15)N, 18:2n-6, and 20:1n-11 were chosen to classify wild samples from different fishing zones. In both cases, 18:2n-6 and delta(15)N were determinant for classification purposes. We would like to emphasize that IRMS produces rapid results and could be the most promising technique to distinguish wild fish of different origin. Similarly, fatty acid composition could be used to easily distinguish farmed from wild samples.     

Water quality requirement of Atlantic salmon (Salmo salar) in water undergoing acidification or liming in Norway

Atlantic salmon are severely affected by acidification in Norway. Water quality criteria for the salmon have to be based on the most sensitive stage, the smolt stage. The sensitivity to acidic water increases enormously during smolting, the seawater tolerance being especially vulnerable. Even moderately acidic water (pH about 6) with low inorganic monomeric aluminium (LA1) concentrations (<20μg. L^?1) and short-term episodes may be harmful. Mixing zones in limed or unlimed rivers may also represent a problem for seaward migrating smolts. In limed salmon rivers, the national liming goal has been increased to pH 6.5 during smolting (1 February to 1 July) and to 6.2 the rest of the year as a result of our experiments. In contrast to what has been found for brown trout, salmon strains originating from watercources undergoing acidification were not more tolerant than those from non-acidic watercourses. At the moment no such “tolerant” strains are available for restocking limed rivers in Norway.     

Baking reduces prostaglandin, resolvin, and hydroxy-fatty acid content of farm-raised Atlantic salmon (Salmo salar)

The consumption of seafood enriched in n-3 polyunsaturated fatty acids (PUFA) is associated with a decreased risk of cardiovascular disease. Several n-3 oxidation products from eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (22:6n-3) have known protective effects in the vasculature. It is not known whether the consumption of cooked seafood enriched in n-3 PUFA causes appreciable consumption of lipid oxidation products. We tested the hypothesis that baking Atlantic salmon (Salmo salar) increases the level of n-3 and n-6 PUFA oxidation products over raw salmon. We measured the contents of several monohydroxy-fatty acids (MHFA), prostanoids, and resolvins. Our data demonstrate that baking did not change the overall total levels of MHFA. However, baking resulted in selective regioisomeric loss of hydroxy fatty acids from arachidonic acid (20:4n-6) and EPA, while significantly increasing hydroxyl-linoleic acid levels. The contents of prostanoids and resolvins were reduced several-fold with baking. The inclusion of a coating on the salmon prior to baking reduced the loss of some MHFA but had no effect on prostanoid losses incurred by baking. Baking did not decrease n-3 PUFA contents, indicating that baking of salmon is an acceptable means of preparation that does not alter the potential health benefits of high n-3 seafood consumption. The extent to which the levels of MHFA, prostanoids, and resolvins in the raw or baked fish have physiologic consequence for humans needs to be determined.     

Biochemical and functional properties of Atlantic salmon (Salmo salar) muscle proteins hydrolyzed with various alkaline proteases

Protein hydrolysates (5, 10, and 15% degrees of hydrolysis) were made from minced salmon muscle treated with one of four alkaline proteases (Alcalase 2.4L, Flavourzyme 1000L, Corolase PN-L, and Corolase 7089) or endogenous digestive proteases. Reaction conditions were controlled at pH 7.5, 40 degrees C, and 7.5% protein content, and enzymes were added on the basis of standardized activity units (Azocoll units). Proteases were heat inactivated, insoluble and unhydrolyzed material was centrifuged out, and soluble protein fractions were recovered and lyophilized. Substrate specificities for the proteases was clearly different. Protein content for the hydrolysates ranged from 71.7 to 88.4%, and lipid content was very low. Nitrogen recovery ranged from 40.6 to 79.9%. The nitrogen solubility index was comparable to that of egg albumin and ranged from 92.4 to 99.7%. Solubility was high over a wide range of pH. The water-holding capacity of fish protein hydrolysates added at 1.5% in a model food system of frozen minced salmon patties was tested. Drip loss was on average lower for the fish protein hydrolysates than for egg albumin and soy protein concentrate, especially for Alcalase hydrolysates. Emulsification capacity for fish protein hydrolysates ranged quite a bit (75-299 mL of oil emulsified per 200 mg of protein), and some were better than soy protein concentrate (180 mL of oil emulsified per 200 mg of protein), but egg albumin had the highest emulsifying capacity (417 mL of oil emulsified per 200 mg of protein). Emulsification stability for fish protein hydrolysates (50-70%) was similar to or lower than those of egg albumin (73%) or soy protein concentrate (68%). Fat absorption was greater for 5 and 10% degrees of hydrolysis fish protein hydrolysates (3.22-5.90 mL of oil/g of protein) than for 15% hydrolysates, and all had greater fat absorption than egg albumin (2. 36 mL of oil/g of protein) or soy protein concentrate (2.90 mL of oil/g of protein).     

Base additions to flowing acidic water: Effects on smolts of Atlantic salmon (Salmo salar L.)

Acidic, Al-rich soft water (pH=5.1, Ca=1.0 mg L^?1 and labile Al=160 μg Al L^?1) was treated by addition of soda (Na ₂Co₃) and lime slurry (CaCO₃). Seven different water qualities of each type of treatment, covering the pH-range 5.1 to 8.2, were prepared in a flow-through system. Smolts of Atlantic salmon (Salmo salar L.) were used as test fish. In both types of treatment, mortality occurred at all pH-levels below 6.05. Above pH 6.05 no mortality occurred using lime slurry. Using soda, 10 % mortality occurred within 48 hr at pH above 7 due to the toxicity of aluminate at low levels of Ca. Plasma chloride levels indicated no physiological stress in the pH-range 6.45 to 7.0.     

Fish kills of Atlantic salmon (Salmo salar) and brown trout (Salmo trutta) in an acidified river of SW Norway

This paper documents population responses of Atlantic salmon and brown trout to fish kills in River Vikedal, an acidified river in SW Norway. The angling statistics show that the adult population of Atlantic salmon in the river has decreased to low numbers during recent years, whereas catches of migrant brown trout have increased in the same period. A total of 659 dead salmon and trout were either collected or observed during spring snowmelt in the years 1982–1985. Parr suffered the highest mortality, and most large specimens. Only a few dead kelts were registered. In the springs of most unfavourable water quality and most severe episods of fish kills (1983 and 1984), salmon parr mortality were significantly higher than that of brown trout. Episodic death of parr in the spring is thought to be an important cause of the reduction in the adult stock of Atlantic salmon in the river during recent years.     

Effects of different cooking procedures on lipid quality and cholesterol oxidation of farmed salmon fish (Salmo salar)

Salmon fillets were steamed, or pan-fried without oil, with olive oil, with corn oil, or with partially hydrogenated plant oil. The exchange between the salmon and the pan-frying oils was marginal, but it was detectable as slight modifications in the fatty acid pattern and the tocopherol contents according to the oil used. Primary and secondary oxidation products were only slightly increased or remained unchanged, which indicated a slight lipid oxidation effect due to the heating procedures applied. The same was observed for tocopherol levels, which remained almost stable and were not affected by the oxidation process. The sum of cholesterol oxidation products (COPs) increased after the heating processes from 0.9 microg/g in the raw sample to 6.0, 4.0, 4.4, 3.3, and 9.9 microg/g extracted fat in pan-fried without oil, with olive oil, corn oil, partially hydrogenated plant oil, and steamed, respectively. A highly significant correlation was found between the fatty acid pattern and the total amount of COPs (r2 = 0.973, p < 0.001). No change has been determined in the n-3 fatty acids content and in the polyunsaturated/saturated-ratio of the cooked salmon fillets. Moderate pan-frying (6 min total) and steaming (12 min) of salmon did not accelerate lipid oxidation but significantly increased the content of COPs. The highest increase of COPs was found through steaming, mainly due to the longer heat exposure. The used frying oils did not influence the outcome; no significant difference between heat treatment with or without oil has been determined.     

Determination of emamectin residues in the tissues of Atlantic salmon (Salmo salar L.) using HPLC with fluorescence detection.

An accurate, reliable, and reproducible assay for the determination of residual concentrations of emamectin B(1a) in muscle, skin, and intact muscle/skin in natural proportions from Atlantic salmon treated with SCH 58854 (emamectin benzoate) is described. The determinative method was developed and validated using fortified control tissues at five levels over a range of 50-800 ng/g as well as tissues containing incurred levels in the same range. Incurred tissues were obtained from a metabolism study of [(3)H]emamectin benzoate in Atlantic salmon. The assay employs processing of a tissue ethyl acetate extract on a propylsulfonic acid solid phase extraction cartridge, followed by derivatization with trifluoroacetic anhydride in the presence of N-methylimidazole. Following separation using reversed phase HPLC, the amount of derivatized emamectin B(1a) is determined by fluorescence detection. The theoretical limits of detection were determined from the analysis of control tissue matrices to be 2.6, 3.3, and 3.8 ng/g as emamectin B(1a) for muscle, skin, and intact muscle/skin, respectively. Likewise, the theoretical limits of quantitation (LOQ) were determined to be 6.9, 8.1, and 9.5 ng/g as emamectin B(1a) for muscle, skin, and intact muscle/skin, respectively. The lowest fortification level used for method validation was 50 ng/g, which served as the effective LOQ for the method. The overall percent recoveries (+/-% CV) were 94.4 +/- 6.89% (n = 25) for muscle, 88.4 +/- 5.35% (n = 25) for skin, and 88.0 +/- 3.73% for intact muscle/skin (n = 25). Accuracy, precision, linearity, selectivity, and ruggedness were demonstrated. The structure of the final fluorescent derivative of emamectin B(1a) free base was identified by ESI(+)/LC-MS. The frozen storage stability of [(3)H]emamectin B(1a) in tissues with incurred residues was demonstrated for approximately 15 months by radiometric analysis and for an additional approximately 13 months by fluorometric analysis for a total of approximately 28 months.     

The effects of liming on juvenile stocks of Atlantic salmon (Salmo salar) and brown trout (Salmo trutta) in a Norwegian river

The effects of liming on juvenile stocks of Atlantic salmon (Salmo salar) and brown trout (Salmo trutta) in the river Vikedalselva in southwestern Norway were assessed. From 1987 to 1989, the river was limed only during the spring snow melt, and pH varied in the range between 5.5 and 7.0. In 1990 to 1993, the river was limed to pH 6.2 from 15 February to 1 June and to pH 5.7 during the rest of the year. Since 1994, the pH during late winter and spring was maintained above 6.5. Prior to liming fish kills were evident during spring snow melt, but these have not occurred since liming. Electrofishing in the autumn between 1981 and 1994 showed no significant change in densities of juvenile salmon and brown trout after liming, mean densities ranged between 19–50 and 9–32 individuals 100 m^–2 respectively. A significant linear correlation between production and biomass of both species was found, indicating that factors directly controlling density affect juvenile production and cause production to remain below carrying capacity. In spite of a clear increase in pH and a reduction in the concentration of labile aluminium after liming, the conditions still do not seem to be optimal for juvenile salmonids. We suggest that a complexity of different factors impose limitations on fish production in the river: inadequate egg deposition, environmental factors such as water temperature and flow, osmoregulatory failure in mixing zones between limed and acidic water and gill damage through deposition of aluminium and iron. However, there are several indications of a reduction in toxic effects after the pH was raised to 6.5 during spring snow melt.     

Investigations on the effects of growth rate and dietary vitamin C on skeletal muscle collagen and hydroxylysyl pyridinoline cross-link concentration in farmed Atlantic salmon (Salmo salar)

We have investigated the interactions between dietary vitamin C levels (at 33, 79, 135, and 424 mg kg-1 of wet mass feed) and growth rate on the collagen and cross-link contents of fast muscle in farmed juvenile Atlantic salmon (Salmo salar L.). The growth rate was measured over an 11 week period using the thermal growth coefficient (TGC). Alkaline-soluble (0.1 M NaOH) (a-s) hydroxyproline (HYP) and alkaline-insoluble (i-s) HYP were determined as a measure of collagen content and hydroxylysyl pyridinoline (PYD) as a measure of mature collagen cross-link concentration. There was a approximately 5-fold increase in muscle vitamin C concentration at similar feed conversion ratios ( approximately 0.82) as dietary vitamin C levels increased from 39 to 424 mg kg-1 of wet mass feed. However, even the lowest dietary vitamin C was sufficient for normal skeletal development and growth. The lowest dietary vitamin C level tested resulted in a approximately 27% decrease in the a-sHYP concentration relative to the other diets, whereas there was no significant effect of vitamin C on the i-sHYP and PYD concentrations. ANOVA revealed no significant interaction between vitamin C and growth rate, whereas the covariate TGC was significant for i-sHYP and PYD but not for a-sHYP. Pyridinoline cross-link and i-s HYP concentrations were 11.1 and 7.7% lower, respectively, in high (TGC > 3.9) mass than low (TGC < 3.9) growth rate fish. These small differences in collagen cross-linking were associated with a 15.6% decrease in fillet firmness measured with an instrumental texture analyzer. It was concluded that for healthy juvenile salmon reared under controlled growth conditions, the dietary vitamin C inclusion of 79 mg kg-1 of wet mass feed was sufficient to produce the required synthesis of soluble muscle collagen. Furthermore, post-translational modifications of the collagen leading to cross-linking showed a small decrease with increasing growth rate but was independent of vitamin C concentration in the diet at these levels.     

Tailoring of Atlantic salmon (Salmo salar L.) flesh lipid composition and sensory quality by replacing fish oil with a vegetable oil blend

Atlantic salmon (Salmo salar L.) juveniles were fed either 100% fish oil (FO), 75% vegetable oil (VO), or 100% VO throughout their life cycle to harvest weight followed by a finishing diet period when all groups were fed 100% FO. The two experimental VO diets were tested at two different locations (Scotland and Norway) against the same control diet (100% FO). The VO blend was composed of rapeseed oil, palm oil, and linseed oil using capelin oil as a control for fatty acid class compositions. Flesh fatty acid profiles were measured regularly throughout the experiment, with the times of sampling determined by changes in pellet size/lipid content and fish life stage. Growth and mortality rates were not significantly affected by dietary fatty acid compositions throughout the life cycle, except during the seawater winter period in Norway when both growth and protein utilization were increased in salmon fed 100% VO compared to 100% FO. Flesh fatty acid composition was highly influenced by that of the diet, and after the finishing diet period the weekly intake recommendations of very long chain n-3 polyunsaturated fatty acid (VLCn-3 PUFA) for human health were 80 and 56% satisfied by a 200 g meal of 75% VO and 100% VO flesh, respectively. No effect on flesh astaxanthin levels was observed in relation to changing dietary oil sources. Sensory evaluation showed only minor differences between salmon flesh from the dietary groups, although prior to the finishing diet period, flesh from 100% VO had less rancid and marine characteristics and was preferred over flesh from the other dietary groups by a trained taste panel. After the finishing diet period, the levels of typical vegetable oil fatty acids in flesh were reduced, whereas those of VLCn-3 PUFA increased to levels comparable with a 100% FO fed salmon. No differences in any of the sensory characteristics were observed between dietary groups. By blending VOs to provide balanced levels of dietary fatty acids, up to 100% of the fish oil can be replaced by the VO blend without compromising growth or flesh quality. At the same time, 75% of the dietary fish oil can be replaced without compromising flesh VLCn-3 PUFA content, thereby providing a beneficial nutritional profile for human consumption.     

Effects of brine salting with regard to raw material variation of Atlantic salmon (Salmo salar) muscle investigated by Fourier transform infrared microspectroscopy

Atlantic salmon fillets differing with regard to raw material characteristics (prerigor, postrigor, frozen/thawed) and salt content were investigated by FT-IR microspectroscopy and light microscopy. Local variation within each salmon fillet was further taken into account by sampling from the head and tail part separately as they vary in fat and moisture content. The highest salt uptake was achieved for frozen/thawed quality during brine-salting with 16% NaCl for 4 h, while the uptake was least for prerigor fish. At the same time, salting caused muscle fiber swelling of about 10% for both frozen/thawed and postrigor qualities. Differences in the FT-IR amide I spectral region were observed implying a change in the muscle protein secondary structure. Prerigor was least affected by brine-salting, having a final salt concentration of 2.2%, while postrigor had a NaCl content of 3.0% and frozen/thawed of 4.1%. Local variation within the fillets had an effect on the amide I absorption characteristics before as well as after salting. Salt uptake of the samples was affected by raw material quality and at the same time the degree of swelling of the myofibers was influenced by raw material character.     

A summary of the impact of acid rain on atlantic salmon (Salmo salar) in Canada

Within the present North American range of Atlantic salmon, severe acid rain effects are limited to the Southern Upland area of Nova Scotia. In the Southern Upland, long range transport of H₂SO₄ has caused many rivers to decline in pH to the point where their Atlantic salmon stocks have been destroyed or much diminished. Chemical records show a declining pH trend in N.S. rivers since the early 1950s. Eighty % of the annual variation in H⁺ concentration can be accounted for by a multiple linear regression model on excess sulphate, total Al and organic anions. It is technically feasible to restore the acidified salmon habitat by the addition of limestone; the total cost of mounting a liming program to restore the lost habitat has been estimated at $4.75 × 10⁶ yr^?1. The pre-acidification Atlantic salmon production capacity of the Southern Upland was estimated from physical habitat surveys and tag return data to be about 45 000 fish yr^?1. Acidification has caused a 50% decline to the current production level of about 23 000 fish yr^?1. The costs of the liming program, when compared to the economic benefits of the anticipated salmon enhancement, are economically unjustifiable. The eradication of salmon from such large regions will hinder future programs to reestablish the species in their former range when pollution of the atmosphere is eventually brought under control. Present plans are for a small liming program to establish a series of refuges for the preservation of nuclei of native salmon stocks.     

Responses of atlantic salmon (Salmo salar) alevins to dissolved organic carbon and dissolved aluminum at low pH

Mortality of Atlantic salmon alevins in solutions containing Al and dissolved organic anions (both synthetic and natural) was correlated with Al accumulation in alevin tissues. Both mortality and accumulation could be related to the concentration differences between Al and organic anions. Mortality and body accumulation of Al both increased dramatically as total Al concentrations increasingly exceeded organic anion concentrations. Alevin growth and yolk utilization were both less rapid at inorganic monomeric Al concentrations exceeding 2 μM (50 μg L^-1). The acidic fractions of dissolved organic matter (DOM) are more effective in protecting alevins against Al toxicity than are the neutral and basic fractions. Ambient inorganic monomeric Al is probably not toxic to salmon alevins in acidic Nova Scotian streams, even during snow-melt.     

Use of two-dimensional electrophoresis to evaluate proteolysis in salmon (Salmo salar) muscle as affected by a lactic fermentation

Two-dimensional electrophoresis was used to study proteolysis in salmon fillets inoculated or not with the starter culture Lactobacillus sake LAD. Protein fragments appeared increasingly with time in both samples, indicating that the main quantitative changes were due to endogenous enzymes. In the most acidic zone (pI = 4-6. 20) particularly, proteolysis was overall independent from processing. In contrast, fermentation had a significant effect in the pH range 6.20-8.35, suggesting a specificity of the bacterial proteases of L. sake toward alkaline to slightly acidic proteins. Furthermore, fragments surrounding tropomyosin (apparent pI = 4.70) appeared in fermented samples, indicating that the protein may be a suitable substrate for the metabolism of L. sake LAD.     

Restoration of fillet n-3 long-chain polyunsaturated fatty acid is improved by a modified fish oil finishing diet strategy for atlantic salmon (Salmo salar L.) smolts fed palm fatty acid distillate

Reducing the lipid content in fish prior to feeding a fish oil finishing diet (FOFD) has the potential to improve n-3 long-chain (≥ C(20)) polyunsaturated fatty acid (LC-PUFA) restoration. This study had two main objectives: (1) determine whether feeding Atlantic salmon smolt a 75% palm fatty acid distillate diet (75PFAD) improves the apparent digestibility (AD) of saturated fatty acids (SFA) and (2) examine whether a food deprivation period after growth on 75PFAD leads to higher n-3 LC-PUFA restoration in the fillet when applying a FOFD. The AD of SFA was higher for 75PFAD compared to that of a fish oil (FO) diet. The relative level (as % total fatty acids (FA)) of n-3 LC-PUFA was higher in unfed fish compared to that in continuously fed fish after 21 and 28 day FOFD periods, respectively. Our results suggest that a food deprivation period prior to feeding a FOFD improves the efficiency of n-3 LC-PUFA restoration in the fillet of Atlantic salmon smolt.     

Effects of fish meal replacement with full-fat soy meal on growth and tissue fatty acid composition in Atlantic cod (Gadus morhua)

Atlantic cod of initial mean weight approximately 220 g were fed a control diet and three diets in which fish meal (FM) was replaced with increasing levels of full-fat soybean meal (FFS) supplied at 12, 24, and 36% of dry diet, for 12 weeks. There were no significant differences in final weights, but the specific growth rate (SGR) was significantly higher in fish fed the control (FFS0) diet compared to fish fed the FFS12 and FFS36 diets, and the feed conversion ratio (FCR) was significantly lower in fish fed the FFS0 diet compared to the other three treatments. The fatty acid (FA) compositions of the cod muscle and liver were highly affected by dietary treatment, and linear relationships between dietary and tissue FA concentrations were shown for some of these. Moreover, selective utilization or accumulation in the tissues of specific FA was suggested by the results.     

An integrated comparison of captive-bred and wild Atlantic salmon (Salmo salar): Implications for supportive breeding programs

Supportive breeding is a strategy consisting in maintaining a pool of locally-adapted wild genitors in captivity whose offspring are released in the wild at an early developmental stage. In this study, we tested the utility of this strategy in preventing phenotypic and genetic divergences between captive-bred and wild animals that could be detrimental for wild populations. Combining microsatellite analyses, morphological measurements and behavioural trials in the laboratory, we compared the progeny of Atlantic salmon (Salmo salar) born in captivity with individuals born in the wild. At all these levels, we found significant differences between the progeny of the two groups. Specifically, allelic frequencies significantly differed between groups, with captive-bred fish tending to be less variable with lower heterozygosity and allelic richness values. The shape of wild-born fish was also different from that of the captive-group, particularly in the depth of the head and the length of the pectoral fins. Finally, captive-bred individuals were, on average, more aggressive than wild-born fish. We demonstrated that this difference was strongly dependent upon the environment as captive-bred fish were more aggressive only when together with their wild conspecifics or with an exotic competitor, the rainbow trout (Oncorhynchus mykiss). Overall, our results showed that both phenotypic and genetic changes can arise even if genitors share a common brood-stock and after only a few months of rearing in a controlled environment. We conclude that the progeny produced in such supportive breeding programs does not meet the criteria necessary to ensure preserving the genetic and ecological integrity of wild populations.     

Fatty acid composition of yak (Bos grunniens) cheese including conjugated linoleic acid and trans-18:1 fatty acids

The esterified fatty acid composition of cheese (YC) from yak ( Bos grunniens), reared in the highlands of the Nepalese Himalayas, was studied using capillary gas-liquid chromatography and compared with that of dairy cow Cheddar cheese (DC) purchased in a local market. The YC was collected from Dolakha, Nepal. The YC had a lower (P<0.001) myristic acid (C14:0; 6.7 vs 10.3%, YC vs DC, respectively) and palmitic acid content (C16:0; 23.3 vs 29.2%, YC vs DC, respectively) compared to DC. The YC had a lower (P<0.01) total medium-chain saturated fatty acids (C10:0-C16:0) content compared to DC (36.7 vs 47.3%, YC vs DC, respectively). On the other hand, the YC had a 24.8% higher (P<0.01) level of total long-chain saturated fatty acids (C17:0-C26:0) and a 3.2 times higher (P<0.001) content of total n-3 PUFA than DC. The ratio of n-3 PUFA to n-6 PUFA in YC was 0.87 compared to 0.20 in DC. YC had a 2.8 times higher (P<0.001) total trans-18:1 (9.18 vs 3.31%, YC vs DC, respectively) content. The percentage of vaccenic acid ( trans-11-C18:1) in YC was 4.6 times higher (6.23 vs 1.35% of total fatty acids, YC vs DC, respectively) than in DC. Vaccenic acid constituted 67.9% of total trans-C18:1 in YC. The Delta9-desaturase index for YC was lower than that of DC. The total conjugated linoleic acid (CLA) content in YC was 2.3% of total fatty acids compared to 0.57% in DC. The cis-9, trans-11 CLA isomer in YC constituted 88.5% of the total CLA. The results suggest that cheese from yak, grazed on Himalayan alpine pastures, may have a more healthful fatty acid composition compared to cheese manufactured from dairy cattle fed grain-based diets.     

Variability of oil content and of major fatty acid composition in almond (Prunus amygdalus Batsch) and its relationship with kernel quality

Oil content and fatty acid composition were determined for two years in the kernel oil of eight cultivars and 47 advanced self-compatible almond genotypes developed in an almond breeding program. Considerable variation between genotypes was found for all parameters. Oil content ranged from 48% to 67% of the total kernel dry weight but was consistent over the two years. Fatty acid composition was also very variable, with significant differences between genotypes, even in genotypes of the same progeny. Oleic acid, ranging from 63% to 78%, and linoleic acid, ranging from 12% to 27%, were the major fatty acids, showing higher values in some selections than in their parents. The large variability observed for all fatty acids and the presence of selections with higher oil and fatty acid contents than the commercial cultivars represents a very promising base to obtain new almond cultivars with oil of higher quality, satisfying the industrial and consumer sectors.