A direct method for fatty acid methyl ester synthesis: application to wet meat tissues, oils, and feedstuffs

Effect of dietary soybean oil addition on the odd-numbered and branched-chain fatty acids in rabbit meat

The effect of dietary soybean oil (SO) inclusion (20g/kg) on the odd-numbered (ONFA) and branched-chain (BCFA) fatty acids (FA) of two muscles, differing in fatness (Longissimus lumborum and Biceps femoris), was studied in 24 New ZealandxCalifornian rabbits. The increased muscle fatness in Biceps femoris (P<0.001) was related to higher saturated (P<0.01) and monounsaturated (P<0.01) fatty acids. Intramuscular ONFA and BCFA contents were not affected, but their proportions were reduced (P<0.01 and P<0.001) by SO addition, suggesting a dilution effect of the dietary polyunsaturates accumulated in both muscles, except for 17:0i which decreased only in Longissimus lumborum due to significant (P<0.05) soybean oilxmuscle interaction. The higher (P<0.05) BCFA contents and the FA profile in Biceps femoris were not affected by fatness, indicating an association with other muscle properties. The present study supplies new information on ONFA and BCFA in rabbit meat.

Increased lipid accumulation in the Chlamydomonas reinhardtii sta7-10 starchless isoamylase mutant and increased carbohydrate synthesis in complemented strains

The accumulation of bioenergy carriers was assessed in two starchless mutants of Chlamydomonas reinhardtii (the sta6 [ADP-glucose pyrophosphorylase] and sta7-10 [isoamylase] mutants), a control strain (CC124), and two complemented strains of the sta7-10 mutant. The results indicate that the genetic blockage of starch synthesis in the sta6 and sta7-10 mutants increases the accumulation of lipids on a cellular basis during nitrogen deprivation relative to that in the CC124 control as determined by conversion to fatty acid methyl esters. However, this increased level of lipid accumulation is energetically insufficient to completely offset the loss of cellular starch that is synthesized by CC124 during nitrogen deprivation. We therefore investigated acetate utilization and O(2) evolution to obtain further insights into the physiological adjustments utilized by the two starchless mutants in the absence of starch synthesis. The results demonstrate that both starchless mutants metabolize less acetate and have more severely attenuated levels of photosynthetic O(2) evolution than CC124, indicating that a decrease in overall anabolic processes is a significant physiological response in the starchless mutants during nitrogen deprivation. Interestingly, two independent sta7-10:STA7 complemented strains exhibited significantly greater quantities of cellular starch and lipid than CC124 during acclimation to nitrogen deprivation. Moreover, the complemented strains synthesized significant quantities of starch even when cultured in nutrient-replete medium.

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.

Impact of administered bifidobacterium on murine host fatty acid composition

Recently, we reported that administration of Bifidobacteria resulted in increased concentrations of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in murine adipose tissue [1]. The objective of this study was to assess the impact of co-administration of Bifidobacterium breve NCIMB 702258 and the substrate for EPA, alpha-linolenic acid, on host fatty acid composition. alpha-Linolenic acid-supplemented diets (1%, wt/wt) were fed to mice (n = 8), with or without B. breve NCIMB 702258 (daily dose of 10(9) microorganisms) for 8 weeks. Two further groups received either supplement of B. breve alone or unsupplemented diet. Tissue fatty acid composition was assessed by gas liquid chromatography. Dietary supplementation of alpha-linolenic acid resulted in higher (P < 0.05) alpha-linolenic acid and EPA concentrations in liver and adipose tissue and lower (P < 0.05) arachidonic acid in liver, adipose tissue and brain compared with mice that did not receive alpha-linolenic acid. Supplementation with B. breve NCIMB 702258 in combination with alpha-linolenic acid resulted in elevated (P < 0.05) liver EPA concentrations compared with alpha-linolenic acid supplementation alone. Furthermore, the former group had higher (P < 0.05) DHA in brain compared with the latter group. These results suggest a role for interactions between fatty acids and commensals in the gastrointestinal tract. This interaction between administered microbes and fatty acids could result in a highly effective nutritional approach to the therapy of a variety of inflammatory and neurodegenerative conditions.

Individual variation and intraclass correlation in arachidonic acid and eicosapentaenoic acid in chicken muscle

Chicken meat with reduced concentration of arachidonic acid (AA) and reduced ratio between omega-6 and omega-3 fatty acids has potential health benefits because a reduction in AA intake dampens prostanoid signaling, and the proportion between omega-6 and omega-3 fatty acids is too high in our diet. Analyses for fatty acid determination are expensive, and finding the optimal number of analyses to give reliable results is a challenge. The objective of the present study was i) to analyse the intraclass correlation of different fatty acids in five meat samples, of one gram each, within the same chicken thigh, and ii) to study individual variations in the concentrations of a range of fatty acids and the ratio between omega-6 and omega-3 fatty acid concentrations among fifteen chickens. Fifteen newly hatched broilers were fed a wheat-based diet containing 4% rapeseed oil and 1% linseed oil for three weeks. Five muscle samples from the mid location of the thigh of each chicken were analysed for fatty acid composition. The intraclass correlation (sample correlation within the same animal) was 0.85-0.98 for the ratios of total omega-6 to total omega-3 fatty acids and of AA to eicosapentaenoic acid (EPA). This indicates that when studying these fatty acid ratios, one sample of one gram per animal is sufficient. However, due to the high individual variation between chicken for these ratios, a relatively high number of animals (minimum 15) are required to obtain a sufficiently high power to reveal significant effects of experimental factors (e.g. feeding regimes). The present experiment resulted in meat with a favorable concentration ratio between omega-6 and omega-3 fatty acids. The AA concentration varied from 1.5 to 2.8 g/100 g total fatty acids in thigh muscle in the fifteen broilers, and the ratio between AA and EPA concentrations ranged from 2.3 to 3.9. These differences among the birds may be due to genetic variance that can be exploited by breeding for lower AA concentration and/or a more favorable AA/EPA ratio to produce meat with health benefits.

Prime Australian lamb supplies key nutrients for human health

This study investigated genetic and non-genetic factors affecting the iron, zinc and omega-3 fatty acid levels of fresh lamb meat. Results from the 2007 progeny of the Australian Sheep Industry Cooperative Research Centre Information Nucleus flock, ~2000 lambs, are presented here. The average level of iron and zinc in lamb muscle was 2.05 and 2.31 mg/100 g, respectively. The iron level was 103% of that required to claim lamb as a ‘good source’ of iron for men of all ages and women older than 50 years, and the average level of zinc was 116% of that required to claim lamb as a ‘good source’ of zinc for women, but was insufficient for a ‘good source’ claim for men. The iron and zinc content of muscle were affected (P < 0.001) by age at slaughter, sex, site at which the lambs were reared, and sire (independent of breed). Lambs from all sites reached the ‘source’ claim for iron for all adults and lambs from all sites, expect lambs from the Cowra and Hamilton sites, had greater iron levels than that required for a ‘good source’ claim for men and women over 50 years old. For zinc, all sites reached the ‘source’ and ‘good source’ claim for men and women, respectively. The major sources of variation in omega-3 fatty acid levels were site and kill group within site (P < 0.001), most likely reflecting nutritional differences associated with the availability of green feed. The eicosapentaenoic acid + docosahexaenoic acid values for all sites indicated that lambs from the Cowra, Rutherglen and Struan sites had adequate levels for a ‘source’ claim of omega-3. The overall average level of eicosapentaenoic acid + docosahexaenoic acid in lamb meat was 23.5 mg/100 g, which is higher than the level required to claim lamb as a ‘source’ of omega-3. The effect of sire on omega-3 fatty acid level was small, but statistically significant (P < 0.001). These results confirm that lamb can represent a ‘source’ or ‘good source’ of these nutrients.

Influence of finishing systems and sampling site on fatty acid composition and retail shelf-life of lamb

Thirty 7-month-old crossbred lambs (Poll Dorset × Border Leicester × Merino) finished over 5 weeks on either low quality pasture or grain-with-hay on a farm in southern Victoria were assessed for carcass parameters, muscle fat composition and retail colour stability. Lambs on the grain diet had a mix of barley grain (80%) and lentils (20%) at 800 g/head.day (air-dry basis ~ad libitum) with cape weed (Arctotheca calendula) hay available at all times. Lambs under grazing had predominantly rye grass (Lolium perenne) and barley grass (Hordeum leporinum) available ad libitum. Carcass weight tended to be higher (P = 0.14) in grain-fed lambs than in grass-fed lambs, but fatness indicated by GR (total muscle + fat tissue thickness at 11 cm from midline) did not differ between feeding systems. Fatty acid composition was determined in the loin from the forequarter (M. longissimus thoracis) and lumbar (M. longissimus lumborum) regions and from the leg region (M. semimembranosus). This showed that grain-finished lamb had higher muscle fat (P < 0.001) and omega-6 fatty acid (P < 0.001) content. Alpha-linolenic acid, eicosapentaenoic acid (EPA) or total omega-3 fat did not differ (P > 0.05) between feeding groups. Saturated fatty acids were greater (P < 0.01) in both loin sampling sites than the leg. The levels of EPA, docosahexaenoic acid and docosapentaenoic acid were lower (P < 0.01) in the forequarter (9%) or lumbar (11%) sites than the leg sampling site. The distribution pattern of fatty acids across the three sampling sites did not differ between feed types. Retail colour stability determined over 4 days of display (only performed in muscle from the lumbar site), evaluated by the redness (HunterLab a*-value) and metmyoglobin formation (reflectance ratio at 630 : 580-nm wavelengths) was superior for grass-fed lamb compared with short-term grain-finished lamb. The results demonstrate that the health claimable omega-3 fat mainly EPA or total omega-3 fat content in lamb was not altered by short-term grain finishing compared with lamb finished under pasture grazing conditions.

Effects of intensive or pasture finishing in spring and linseed supplementation in autumn on the omega-3 content of lamb meat and its carcass distribution

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are the n-3 polyunsaturated fatty acids (n-3 PUFA) for which there is ample evidence of human health benefits, and these are also the fatty acids for which there are cut-off points for ‘source’ and ‘good source’ claims. Two consecutive experiments were conducted to determine the effect of finishing systems on the n-3 PUFA content of lamb meat in Western Australia. In experiment I, a 4-week feeding experiment was conducted using 48 Poll Dorset × Merino lambs. The lambs were divided into two lots of 24 (12 males and 12 females) and randomly assigned to either concentrate (C1) finishing on commercial lamb finishing pellets or pasture (P) finishing on kikuyu (Pennisetum clandestinum) pasture. In experiment II, 28 lambs were divided into two groups of 14 lambs (seven males and seven females) and assigned to finishing either on concentrate pellets (C2) or concentrate pellets plus linseed (C2-L). This second experiment was conducted indoors for 10 weeks. The initial liveweight (mean ± s.e.) of the lambs was 43 ± 0.6 and 32.5 ± 0.9 kg for experiments I and II, respectively. At the end of experiment II, three chops each were sampled from the leg, loin, forequarter and neck region of each carcass. The final liveweight (42 ± 0.8 v. 50 ± 1.2 kg), hot carcass weight (19 ± 0.5 v. 24 ± 0.7 kg) and GR depth (5.6 ± 0.6 v. 12.8 ± 0.6 mm) were lower (P < 0.05) for P than C1 lambs. In contrast, C2 and C2-L lambs had similar final liveweight (44 ± 0.7 v. 45 ± 0.9 kg), hot carcass weight (19 ± 0.3 v. 20 ± 0.5 kg) and GR depth (13 ± 1.3 v. 14 ± 1.2 mm). In experiment I, the total n-3 PUFA yields for C1 and P lambs in the M. longissimus lumborum were 67 ± 2.5 and 78 ± 3.2 mg per 100 g muscle, respectively. The EPA plus DHA yields were 17 and 21 mg per 100 g muscle, respectively. The sum of the long-chain (≥C20) n-3 PUFA EPA, docosapentaenoic acid and DHA for C1 and P lambs were 30 and 37 mg per 100 g, respectively. Sex had no effect on any of the n-3 fatty acids. In experiment II, the total n-3 PUFA yields for C2 lambs were 61, 54, 60 and 104 mg per 100 g for leg, loin, forequarter and neck chops, respectively. The respective values for C2-L lambs were 153, 138, 139 and 178 mg per 100 g muscle. The claimable EPA plus DHA yields for C2 lambs were 13, 10, 12 and 15 mg per 100 g of trimmed leg, loin, forequarter and neck chops, respectively. The respective values for C2-L lambs were around 2-fold higher at 27, 21, 25 and 23 mg per 100 g raw meat. All the samples from pasture-finished and linseed-supplemented groups met the 30 mg cut-off point for ‘source’ claim in Australia when the computation was based on 100 g cooked lamb serve (140 g raw). We conclude that pasture-finished lambs have more n-3 PUFA per serve than their counterparts finished indoors on commercial pellets. Further, supplementing indoor-finished lambs with linseed provided equivalent n-3 PUFA per serve to finishing lambs on pasture. Supplementation with an omega-3 source improved omega-3 per serve across the whole carcass irrespective of sex.

Effect of sampling fat location and cooking on fatty acid composition of beef steaks

To investigate the impact of sampling fat location and cooking on fatty acid composition of beef steaks, 21 raw steaks from crossbred steers were dissected to obtain outer (OSC) and inner subcutaneous fat (ISC), seam fat, marbling, and lean muscle. Twenty-one cooked steaks were dissected to obtain OSC, ISC, seam fat, surface and inner muscle. Trans-vaccenic acid and c9, t11-CLA percentages were lower (P<0.05) in lean muscle than subcutaneous (s.c.) fat or marbling. Monounsaturated: saturated fatty acid ratios were lower (P<0.05) in seam fat and marbling than s.c. fat or lean muscle. Linoleic and linolenic acid levels were highest in lean muscle and longer chain n-6 and n-3 fatty acids were only detected in lean muscle. Cooking did not change fatty acid composition dramatically except that n-6: n-3 ratio in s.c. and seam fat decreased after cooking (P<0.05).

Butyrate improves insulin sensitivity and increases energy expenditure in mice

OBJECTIVE

We examined the role of butyric acid, a short-chain fatty acid formed by fermentation in the large intestine, in the regulation of insulin sensitivity in mice fed a high-fat diet.

RESEARCH DESIGN AND METHODS

In dietary-obese C57BL/6J mice, sodium butyrate was administrated through diet supplementation at 5% wt/wt in the high-fat diet. Insulin sensitivity was examined with insulin tolerance testing and homeostasis model assessment for insulin resistance. Energy metabolism was monitored in a metabolic chamber. Mitochondrial function was investigated in brown adipocytes and skeletal muscle in the mice.

RESULTS

On the high-fat diet, supplementation of butyrate prevented development of insulin resistance and obesity in C57BL/6 mice. Fasting blood glucose, fasting insulin, and insulin tolerance were all preserved in the treated mice. Body fat content was maintained at 10% without a reduction in food intake. Adaptive thermogenesis and fatty acid oxidation were enhanced. An increase in mitochondrial function and biogenesis was observed in skeletal muscle and brown fat. The type I fiber was enriched in skeletal muscle. Peroxisome proliferator-activated receptor-gamma coactivator-1alpha expression was elevated at mRNA and protein levels. AMP kinase and p38 activities were elevated. In the obese mice, supplementation of butyrate led to an increase in insulin sensitivity and a reduction in adiposity.

CONCLUSIONS

Dietary supplementation of butyrate can prevent and treat diet-induced insulin resistance in mouse. The mechanism of butyrate action is related to promotion of energy expenditure and induction of mitochondria function.