This fat is obtained from cutaneous adipose tissue of pork. Its fatty acid composition depends on the diet. As an example, linoleic acid content is low (about 2%) when pork is fed with rice but high (about 30%) when soja is used as main food.
The dressed weight of pigs contains about 30% fat but very fat pigs can contain up to 50% fatty matter. The world production of lard is about 8.3 million tons per year (2007-2008).
This fat is extracted from beef adipose tissue. By definition, tallow is fat rendered primarily from cattle, but it also is fat from sheep and goats. Its fatty acid composition depends on the tissue location more than on the food ingested. As lipids are partially hydrogenated in the rumen, 6-8% elaidic acid and traces of conjugated dienes and trienes are detected in beef tallow.
The proportion of fat in the dressed weight varies from 8% up to 25% in fat beef. The world production of beef tallow was about 8.7 million tons in 2007-08 (about 6% of the global fats and oils production).
Accounts of the use of tallow in soapmaking extend back thousands of years (traditional soap is made of about 85% tallow and 15% coconut or palm kernel oil). Tallow was also a part of the world’s first surviving art since prehistoric cave paintings were most probably made using animal tallow mixed with pigments.
While amounts of tallow used for edible purposes in human show slight decline, its use is increasing in animal feeds.
Inedible tallow gives numerous and various derivatives from plastics, lotions, soaps and detergents, tires, candles, paints and varnishes, lubricants and several pharmaceuticals. Tallow is an important factor in the global fatty acids market. These fatty acids play an important role in the formulation of pesticides, herbicides, emulsifiers, and dispersing agents. Several derivatives are produced from tallow : fatty alcohols, amines, amides, esters and glycerol.
This fat is found in bone marrow (about 95% of the dry weight) and is separated during gelatin processing. As phospholipids are present, bone fats are more unsaturated than the other animal fats. Odd carbon number and branched fatty acids are found as in tallow.
They are produced from various bird species and their fatty acid composition depends largely on the food ingested. Chicken fat is characterized by a relatively high proportion (about 10%) of palmitoleic (16:1 n-9) and linoleic acid (18:2 n-6) (about 25%). Fatty liver of duck or goose is characterized by triglycerides rich in oleic acid (about 60%) and containing moderate amounts of palmitic and stearic acids (20 and 15%, respectively).
The average fatty acid compositions (weight percent) of these important fat products are given in the table below:
|
Lard |
Tallow |
Bone |
Poultry |
|
| 14:0 |
1-2 |
3-4 |
1.8-2.5 |
0.2-1.3 |
| 15:0 |
– |
<0.6 |
<1 |
– |
| 16:0 |
22-26 |
23-27 |
23-26 |
22-28 |
| 16:1 |
1.5-3 |
2-4 |
2-4 |
2-9 |
| 17:0 |
<0.5 |
1-1.5 |
1-1.5 |
– |
| 17:1 |
<0.4 |
<1 |
<1 |
– |
| 18:0 |
13-18 |
15-23 |
15-18 |
6-11 |
| 18:1 |
39-45 |
36-43 |
41-45 |
37-53 |
| 18:2 |
8-15 |
1.5-4 |
2-5 |
9-25 |
| 18:3 |
0.5-1.5 |
0.3-1 |
0.5-2 |
<2 |
| 20:0 |
<0.3 |
<0.2 |
– |
– |
| 20:1 |
<1.3 |
<0.5 |
<1 |
– |
| isoC15-18 |
<0.3 |
1-2.5 |
0.6-2 |
– |
INSECTS LIPIDS
The production of insects is promising from the perspective of novel and sustainable food production. They are already well recognized as a very interesting alternative source of proteins but also of lipids (Alvez AV et al., Regul Toxicol Pharmacol 2019, 102, 90). The official production forecast has indicated that a production of one million tons of insect meal may be reached by 2030 in Europe (IPIFF). Depending on the insect species, the content can vary from 10 to 15% in dry weight (Chorthippus parallelus, Conocephalus discolor, Acheta Domesticus) to more than 30% for Tenebrio molitor larvae (Paul A et al., J Asia-Pac Entomol 2017, 20: 337). Despite this potential, the valorization of insect lipids at an industrial scale is today poorly documented and the production volume forecasts of insect lipids are not available.
The fatty acid composition of Tenebrio molitor oil presents a high concentration of unsaturated fatty acids. The main fatty acid is oleic acid (C18:1ω9, 44%), linoleic acid (C18:2ω6, 28%) and palmitic acid (C16:0, 18%). The composition of this oil is very similar to the one of some vegetal oils (especially rice bran and peanut oils) (Orsavova et al., 2015). For Chorthippus parallelus, α-linolenic acid (C18:ω3, 39%) formed the major lipid component, which was followed by oleic acid and linoleic acid. A review of these new lipid sources may be consulted (Lorrette B et al., OCL 2022, 29, 22).
The table below gives the stereospecific distribution of fatty acids in triacylglycerols of depot fats in man and some animals.
| sn | 14:0 | 16:0 | 16:1 | 18:0 | 18:1 | 18:2 | 20:1 | 22:1 | 20:5 | 22:5 | 22:6 | |
| Man | 1 2 3 |
4 11 1 |
39 10 25 |
5 11 4 |
10 2 9 |
33 50 51 |
3 9 5 |
|||||
| Rat | 1 2 3 |
2 1 2 |
32 10 27 |
5 4 5 |
9 1 7 |
32 37 37 |
15 45 17 |
|||||
| Pig | 1 2 3 |
2 4 1 |
16 59 2 |
3 4 3 |
21 3 10 |
44 17 65 |
12 8 24 |
|||||
| Chicken | 1 2 3 |
2 1 1 |
25 15 24 |
12 7 12 |
6 4 6 |
33 43 35 |
14 23 14 |
|||||
| Herring | 1 2 3 |
6 10 4 |
12 17 7 |
13 10 5 |
1 1 1 |
16 10 8 |
3 3 1 |
25 6 20 |
14 5 50 |
3 18 4 |
1 3 1 |
1 13 1 |
| Cod | 1 2 3 |
6 8 4 |
15 16 7 |
14 12 14 |
6 1 1 |
28 9 23 |
2 2 2 |
12 7 17 |
6 5 7 |
2 12 13 |
1 3 1 |
1 20 6 |
Menhaden |
1 2 3 |
12 10.5 5 |
24 20 7 |
18 10.5 9 |
1 2 4 |
13 7.5 13;5 |
1 0.5 3 |
1 0.5 2 |
3 17.5 16 |
1 3 2 |
4 17 6 |
|
Seal Blubber |
1 2 3 |
2 8 0 |
3 12 3 |
8 35 12 |
1 2 1 |
38 23 18 |
0 1 2 |
13 4 17 |
3 0 3 |
8 2 11 |
4 1 8 |
10 2 18 |
| Seal | 1 2 3 |
4 11 1 |
11 13 4 |
15 30 14 |
1 1 1 |
29 30 26 |
1 3 1 |
18 3 16 |
8 1 7 |
3 1 8 |
2 1 6 |
3 1 10 |
Seal blubber and menhaden : data from Wanasundara U et al., J Food Lipids 1997, 4, 51
It can be seen that, as in vegetal oils, the external positions are generally occupied by saturated fatty acids, except in pig where palmitic acid is more abundant at the 2 position. Monoenes are differently distributed, oleic acid being more abundant at positions 2 and 3 in man, at positions 1 and 3 in pig and 2 in chicken. The distribution of 18:2 is also species specific. It must be noticed that fat depots in marine animals are rich in polyunsaturated fatty acids and long-chain monoenes. Results indicate that the stereospecific location of the polyunsaturated fatty acids is in the position 2 (also 3 for 20:5n-3 in cod) in fish but in position 3 for mammals (same in seal, whale and polar bear) or in positions 1 and 3 (seal blubber). This raises the question of the availability of these fatty acids from food expecting a benefic effect on diverse human functions.
Oils from fish and marine mammals are characterized by a large range of fatty acids from 12 to 26 carbon atoms and 0 to 6 double bonds. The bulk of the fatty chains is contributed by saturated (15-25%), monoenes (35-60%) and polyenes (25-40%). Among polyunsaturated, 20:5n-3 and 22:6n-3 are the most prevalent. The study of the structure of the triacylglycerol molecules of marine oils is complex because of their multiplicity and the low and differential hydrolysis by lipases of positions occupied by 20:5 or 22:6n-3, the use of the Grignard reagent being required.
From the above data obtained by chemical degradation as well as those obtained with nuclear magnetic resonance spectroscopy (Aursand M et al., JAOCS 1995, 72, 293), it may be inferred that fish and mammal oils have distinct positional distributions of w3 fatty acids. As an example, in Salmon, cod or herring, 22:5 and DHA are concentrated in the b-position (sn-2), while, in mammals, they are mainly found in the a-position (sn-1,3). This may be important in considering the bioavailability of these important fatty acids after ingestion of marine foods from various origins.
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