http://www.uco.es/zootecniaygestion/img/pictorex/01_10_22_grasa_1.pdf

Fat deposition, fatty acid composition and meat quality: A review

While use of synthetic antioxidants (such as butylated hydroxytoluene and butylated hydroxyanisole) to maintain the quality of ready-to-eat food products has become commonplace, consumer concern regarding their safety has motivated the food industry to seek natural alternatives. Phenolic antioxidants can inhibit free radical formation and/or interrupt propagation of autoxidation. Fat-soluble vitamin E (α-tocopherol) and water-soluble vitamin C (L-ascorbic acid) are both effective in the appropriate matrix. Plant extracts, generally used for their flavoring characteristics, often have strong H-donating activity thus making them extremely effective antioxidants. This antioxidant activity is most often due to phenolic acids (gallic, protocatechuic, caffeic, and rosmarinic acids), phenolic diterpenes (carnosol, carnosic acid, rosmanol, and rosmadial), flavonoids (quercetin, catechin, naringenin, and kaempferol), and volatile oils (eugenol, carvacrol, thymol, and menthol). Some plant pigments (anthocyanin and anthocyanidin) can chelate metals and donate H to oxygen radicals thus slowing oxidation via 2 mechanisms. Tea and extracts of grape seeds and skins contain catechins, epicatechins, phenolic acids, proanthocyanidins, and resveratrol, all of which contribute to their antioxidative activity. The objective of this article is to provide an overview of natural antioxidants, their mechanisms of action, and potential applications.

https://onlinelibrary.wiley.com/doi/epdf/10.1111/j.1541-4337.2011.00156.x

Natural antioxidants: sources, compounds, mechanisms of action, and potential applications

With the increasing amount of evidence linking certain disorders of the human body to a disturbed gut microbiota, there is a growing interest for compounds that positively influence its composition and activity through diet. Besides the consumption of probiotics to stimulate favorable bacterial communities in the human gastrointestinal tract, prebiotics such as inulin-type fructans (ITF) and arabinoxylan-oligosaccharides (AXOS) can be consumed to increase the number of bifidobacteria in the colon. Several functions have been attributed to bifidobacteria, encompassing degradation of non-digestible carbohydrates, protection against pathogens, production of vitamin B, antioxidants, and conjugated linoleic acids, and stimulation of the immune system. During life, the numbers of bifidobacteria decrease from up to 90% of the total colon microbiota in vaginally delivered breast-fed infants to <5% in the colon of adults and they decrease even more in that of elderly as well as in patients with certain disorders such as antibiotic-associated diarrhea, inflammatory bowel disease, irritable bowel syndrome, obesity, allergies, and regressive autism. It has been suggested that the bifidogenic effects of ITF and AXOS are the result of strain-specific yet complementary carbohydrate degradation mechanisms within cooperating bifidobacterial consortia. Except for a bifidogenic effect, ITF and AXOS also have shown to cause a butyrogenic effect in the human colon, i.e., an enhancement of colon butyrate production. Butyrate is an essential metabolite in the human colon, as it is the preferred energy source for the colon epithelial cells, contributes to the maintenance of the gut barrier functions, and has immunomodulatory and anti-inflammatory properties. It has been shown that the butyrogenic effects of ITF and AXOS are the result of cross-feeding interactions between bifidobacteria and butyrate-producing colon bacteria, such as Faecalibacterium prausnitzii (clostridial cluster IV) and Anaerostipes, Eubacterium, and Roseburia species (clostridial cluster XIVa). These kinds of interactions possibly favor the co-existence of bifidobacterial strains with other bifidobacteria and with butyrate-producing colon bacteria in the human colon.

/pdf/bifidobacteria-and-butyrate-producing-colon-bacteria-5e9e3ze4h9.pdf

Bifidobacteria and butyrate-producing colon bacteria: Importance and strategies for their stimulation in the human gut

Simulated gastro-intestinal digestion is widely employed in many fields of food and nutritional sciences, as conducting human trials are often costly, resource intensive, and ethically disputable. As a consequence, in vitro alternatives that determine endpoints such as the bioaccessibility of nutrients and non-nutrients or the digestibility of macronutrients (e.g. lipids, proteins and carbohydrates) are used for screening and building new hypotheses. Various digestion models have been proposed, often impeding the possibility to compare results across research teams. For example, a large variety of enzymes from different sources such as of porcine, rabbit or human origin have been used, differing in their activity and characterization. Differences in pH, mineral type, ionic strength and digestion time, which alter enzyme activity and other phenomena, may also considerably alter results. Other parameters such as the presence of phospholipids, individual enzymes such as gastric lipase and digestive emulsifiers vs. their mixtures (e.g. pancreatin and bile salts), and the ratio of food bolus to digestive fluids, have also been discussed at length. In the present consensus paper, within the COST Infogest network, we propose a general standardised and practical static digestion method based on physiologically relevant conditions that can be applied for various endpoints, which may be amended to accommodate further specific requirements. A frameset of parameters including the oral, gastric and small intestinal digestion are outlined and their relevance discussed in relation to available in vivo data and enzymes. This consensus paper will give a detailed protocol and a line-by-line, guidance, recommendations and justifications but also limitation of the proposed model. This harmonised static, in vitro digestion method for food should aid the production of more comparable data in the future.

https://hal.archives-ouvertes.fr/hal-01209876/document

A standardised static in vitro digestion method suitable for food – an international consensus

Recently, research on natural antioxidants has become increasingly active in various fields. Accordingly, numerous articles on natural antioxidants, including polyphenols, flavonoids, vitamins, and volatile chemicals, have been published. Assays developed to evaluate the antioxidant activity of plants and food constituents vary. Therefore, to investigate the antioxidant activity of chemical(s), choosing an adequate assay based on the chemical(s) of interest is critical. There are two general types of assays widely used for different antioxidant studies. One is an assay associated with lipid peroxidations, including the thiobarbituric acid assay (TBA), malonaldehyde/high-performance liquid chromatography (MA/HPLC) assay, malonaldehyde/gas chromatography (MA/GC) assay, β-carotene bleaching assay, and conjugated diene assay. Other assays are associated with electron or radical scavenging, including the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay, 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) as...

Antioxidant assays for plant and food components.

Meat fatty acid composition is influenced by genetic factors, although to a lower extent than dietary factors. The species is the major source of variation in fatty acid composition with ruminant meats being more saturated as a result of biohydrogenation in the rumen compared to the meat of monogastric animals. The level of fatness also has an effect on the meat fatty acid composition. The contents of saturated (SFA) and monounsaturated (MUFA) fatty acids increase faster with increasing fatness than does the content of PUFA, resulting in a decrease in the relative proportion of PUFA and consequently in the polyunsaturated/saturated fatty acids (P/S) ratio. The dilution of phospholipids with triacylglycerols and the distinct differences in fatty acid composition of these fractions explain the decrease in the P/S ratio with increasing fatness. An exponential model was fitted to the literature data for beef and showed a sharply increasing P/S ratio at low levels of intramuscular fat. Lowering the fat level of beef is thus more efficient in increasing the P/S ratio than dietary interventions. For pork, the intramuscular fat level also affects the P/S ratio, but nutrition will have a larger impact. The fat level also influences the n-6/n-3 PUFA ratio, due to the difference of this ratio in polar and neutral lipids. However, these effects are much smaller than the effects that can be achieved by dietary means. Differences in fatty acid composition between breeds and genotypes can be largely explained by differences in fatness. However, after correction for fat level, breed or genotype differences in the MUFA/SFA ratio and in the longer chain C20 and C22 PUFA metabolism have been reported, reflecting the possible genetic differences in fatty acid metabolism. Breed differences in meat conjugated linoleic acid (CLA) content have not yet been reported, but the c9t11CLA content in meat is positively related to the total fat content. Heritabilities and genetic correlations for the proportion of certain fatty acids have been estimated in a few studies, and correspond to the observations at the phenotypic level in relation to the intramuscular fat level. Although there is potential for genetic change, incorporating fatty acid composition as a goal in classical breeding programs does not seem worthwhile at the present. Enzyme activities have been measured in a few studies, but are not able to explain between-animal variation in fatty acid composition. Biochemical and molecular genetic studies should be encouraged to unravel the mechanisms responsible for differences in the metabolism and incorporation of specific fatty acids in meat. fatty acids / meat / genetics / P/S ratio

https://hal.archives-ouvertes.fr/hal-00890005/document

Meat fatty acid composition as affected by fatness and genetic factors: a review

https://biblio.ugent.be/publication/287402/file/1125991.pdf

Effect of dietary fatty acids on incorporation of long chain polyunsaturated fatty acids and conjugated linoleic acid in lamb, beef and pork meat: a review

https://www.favv-afsca.be/scientificcommittee/publications/articles/_documents/Claeys2014-Rawmilkdifferentspecies-chemicalaspects.pdf

Consumption of raw or heated milk from different species: An evaluation of the nutritional and potential health benefits

The effect of double-muscling (DM) genotype (double-muscling, mh/mh; heterozygous, mh/+; normal, +/+) of Belgian Blue (BB) young bulls on the intramuscular fatty acid composition, in particular conjugated linoleic acid (CLA) and polyunsaturated fatty acids (PUFA) was examined in five different muscles. The relative fatty acid composition showed only minor differences between muscles within genotypes. However, the DM genotype had a large effect on both the intramuscular total fatty acid content and on the relative fatty acid composition. Across muscles, the mh/mh animals had a lower total fatty acid content compared with the +/+animals (907 v: 2656 mg/100 g muscle; P < 0·01) and a higher PUFA proportion in total fatty acids (27·5 v 11·3 g/100 g total fatty acids; P < 0001), resulting in a higher PUFA/saturated fatty acid ratio (0·55 v 0·18; P < 0·01) and a lower n-6/n-3 ratio (5·34 v. 6·17; P < 0·01). The heterozygous genotype was intermediate between the two homozygous genotypes. The relative CLA content was similar in the mh/mh and +/+ genotypes and approximated 0·4 to 0·5 g/100 g total fatty acids. From the data it is further suggested that differences in the metabolism of the n-3 and n-6 fatty acids could exist between DM genotypes.

Effect of double-muscling in Belgian Blue young bulls on the intramuscular fatty acid composition with emphasis on conjugated linoleic acid and polyunsaturated fatty acids

Katleen Raes

Papers

Meat fatty acid composition as affected by fatness and genetic factors: a review

Effect of dietary fatty acids on incorporation of long chain polyunsaturated fatty acids and conjugated linoleic acid in lamb, beef and pork meat: a review

Consumption of raw or heated milk from different species: An evaluation of the nutritional and potential health benefits

Effect of double-muscling in Belgian Blue young bulls on the intramuscular fatty acid composition with emphasis on conjugated linoleic acid and polyunsaturated fatty acids

Meat quality, fatty acid composition and flavour analysis in Belgian retail beef.