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Conjugated Linoleic Acid (CLA) in cheese: Analysis, Composition, and Dietary Intake
Abstract
Cheeses are recognized as major dietary sources of CLA, a group of positional and geometric isomers of linoleic acid (18:2 cis9,cis12) with potential beneficial effects to human health. Bioactivity of CLA is isomer specific and is related to immune modulation, body fat reduction, and protection against atherosclerosis and cancer. Therefore, analytical methodologies to ensure accurate analysis of CLA contents and detailed distribution of positional and geometrical isomers are required. In this chapter we present an overview of the most useful chromatographical techniques, such as Ag+- HPLC and GC-MS. We present reported contents of CLA and the distribution of CLA isomers in cheeses obtained from milk of different ruminant species and using varied cheesemaking processes. These data is discussed, and we contrast the effects of cheese processing conditions, and the variation in cheese CLA resulting from milk fat composition. These factors in combination might explain at least part of the variation in contents of the fifteen CLA isomers identified in cheese. Concerning the effects of processing, heat treatments, ripening conditions and addition of starter cultures are candidates to explain the variation in CLA composition observed in cheeses. Conversely, milk fat composition might be affected by geographical origin, seasonality, and the animalsr diet, which appear to be the major determinant of CLA variation in cheeses. Finally, we discuss the contribution of cheeses for the habitual intake of CLA by population groups that is of concern considering the potential health benefits of CLA.
... In white-mold cheeses (seven Camembert-type cheeses and three Brie-type cheeses) tested by Białek and Tokarz [90], the CLA content ranged from 1.74 mg/g of fat to 3.07 mg/g of fat, and in the blue-veined ones, it ranged from 1.66 mg/g of fat to 2.39 mg/g of fat. The average content of CLA in the Gorgonzola-type cheeses analyzed by Prandini et al. [35] was 5.16 mg/g of fat, whereas, in the Brie cheese studied by Nunez and Torres [91], it was 3.8 mg/g of fat. ...
The assessment of fatty acid composition, including the content of conjugated linoleic acid cis9trans11 C18:2 (CLA) and trans C18:1 and C18:2 isomers in fat extracted from selected high-fat dairy products commonly available to consumers in retail sale on the Polish market, and a comparison of their indicators as to the quality of lipids was the aim of the study. The experimental materials were hard cheeses, white-mold cheeses, blue-veined cheeses, and butters. The conducted study demonstrated that various contents of groups of fatty acids and the values of lipid quality indices were found in the tested products. Butters turned out to be richer sources of short-chain, branched-chain, and odd-chain fatty acids. The fat extracted from butters and white-mold cheeses had a significantly higher (p < 0.05) content of n-3 fatty acids. Lower values of the n-6/n-3 ratio were determined in the fat extracted from butters and white-mold cheeses. The highest values of the thrombogenicity index (TI) were found in fat extracted from hard cheeses. Significantly lower values (p < 0.05) of the atherogenicity index (AI) and values of the H/H ratio were found in fat from mold cheeses. Fat from butters and white-mold cheeses had a significantly higher (p < 0.05) content of CLA and total content of trans C18:1.
... Refiriéndonos a su contenido lipídico, gracias al cual se vehiculizan las vitaminas liposolubles, destacan los ácidos grasos esenciales como el linoleico y el linolénico, así como otros componentes bioactivos de interés como son la esfingomielina, y los ácidos grasos trans presentes de forma natural, cuyo perfil de isómeros es diferente al de las grasas elaboradas por procesos tecnológicos, relacionadas con las enfermedades cardiovasculares 5 . Estas grasas trans son precursoras del ácido linolénico conjugado (CLA) y poseen potenciales efectos beneficiosos para la salud a nivel cardiovascular, antitumoral, y de reducción de peso [5][6][7] . ...
Los péptidos bioactivos son un conjunto de moléculas de naturaleza proteica presentes en la leche de forma natural, con potenciales efectos beneficiosos en el organismo humano. El objetivo es realizar una revisión actualizada de la literatura científica sobre la acción de estos compuestos en el organismo. Se realizó una revisión bibliográfica con la base de datos MEDLINE como fuente de información. Selección de artículos científicos de las últimas 2 décadas y, de entre ellos, los artículos más relevantes sobre los diferentes compuestos y sus múltiples acciones biológicas. Se ha encontrado multitud de publicaciones recientes que registran las acciones biológicas de estos compuestos en el ser humano y muestran sus capacidades de protección de la salud y prevención de diversas patologías. Palabras clave: leche, proteína, péptido, bioactivo.
... Refiriéndonos a su contenido lipídico, gracias al cual se vehiculizan las vitaminas liposolubles, destacan los ácidos grasos esenciales como el linoleico y el linolénico, así como otros componentes bioactivos de interés como son la esfingomielina, y los ácidos grasos trans presentes de forma natural, cuyo perfil de isómeros es diferente al de las grasas elaboradas por procesos tecnológicos, relacionadas con las enfermedades cardiovasculares 5 . Estas grasas trans son precursoras del ácido linolénico conjugado (CLA) y poseen potenciales efectos beneficiosos para la salud a nivel cardiovascular, antitumoral, y de reducción de peso [5][6][7] . ...
Los péptidos bioactivos son un conjunto de moléculas de naturaleza proteica presentes en la leche de forma natural, con potenciales efectos beneficiosos en el organismo humano. El objetivo es realizar una revisión actualizada de la literatura científica sobre la acción de estos compuestos en el organismo. Se realizó una revisión bibliográfica con la base de datos MEDLINE como fuente de información. Selección de artículos científicos de las últimas 2 décadas y, de entre ellos, los artículos más relevantes sobre los diferentes compuestos y sus múltiples acciones biológicas. Se ha encontrado multitud de publicaciones recientes que registran las acciones biológicas de estos compuestos en el ser humano y muestran sus capacidades de protección de la salud y prevención de diversas patologías. Palabras clave: leche, proteína, péptido, bioactivo.
Milk fat from 12 7/8 crossbred Holstein-Zebu lactating dairy cows was used to evaluate the effect of different diets on milk fatty acid (FA) profile and milk CLA content. Cows were fed concentrate containing corn (CR), wheat bran (WB), or dried citrus pulp (CP) supplemented or not with soybean oil. Chromatographic analysis showed a FA recovery greater than 95%. With the exception of milk content of trans-10 C18:1 and proportions of trans-10 C18:1 and trans-11 C18:1 on total milk trans- C18:1, the interaction soybean oil x carbohydrate source was not significant for the remaining measured variables. Overall, carbohydrate source did not affect the milk FA profile or CLA content in this trial. Supplementation with soybean oil increased unsaturated FA by 35% and decreased saturated FA by 14%, mainly short chain FA (9.66 vs. 7.59 g/100 g) and medium chain FA (51.80 vs. 40.86 g/100 g). Soybean oil increased long chain FA (32.17 vs. 46.47 g/100 g), mainly C18:0 (9.44 vs. 13.63 g/100 g), C18:1 (20.28 vs. 29.74 g/100 g) and C18:2 (2.16 vs. 2.92 g/100 g). Feeding soybean oil increased the concentration of cis-9 trans-11 C18:2 CLA by 230% (0.46 vs. 1.06 g/100 g). In addition, the content of cis and trans-C18:1isomers was also increased. Although the trans-11 C18:1 isomer was the most important, concentration of trans-10 C18:1 increased from 0.28 to 1.11 g/100g in oil supplemented-diets being affected by the carbohydrate source. Milk from cows fed CR, WB, and CP showed similar content of trans-10 C18:1. However, in diets with oil supplementation both CR and WB resulted in greater content of trans-10 C18:1 than CP diet suggesting different biohydrogenation pathways.
A total of 52 Italian and French commercial cheeses were analysed for fatty acid composition and conjugated linoleic acid (CLA) concentration. The cheeses were first grouped according to the ruminant species of the milk used in manufacturing, then according to the following criteria: (1) cheeses obtained from milk of the same ruminant species but using different production technologies; (2) cheeses produced from milk of different ruminant species but through similar cheesemaking processes. Comparative studies of fatty acid composition and CLA levels in the different cheese classes were carried out. In our study, the arrangement of the ruminant species according to the increasing CLA concentration in cheese was: goat = cow < sheep. Sheep cheeses had the highest levels of CLA (9.86 mg/g fat), α-linolenic acid (0.75%) and trans-vaccenic acid (1.63%), and the lowest contents of linoleic acid (1.80%) and oleic acid (16.83%). The comparison of cheeses obtained from milk of the same ruminant species but through different production technologies reported statistically significant differences in the fatty acid profiles that could be due to a different degree of lipolysis in the cheeses compared. Nevertheless, statistically significant differences in CLA concentration were not found; this suggests that the factors involved in the cheesemaking process generally do not affect the CLA content in milk fat.
Total conjugated linoleic acid (CLA) concentrations increased 1.32 fold in salted and 1.27 in unsalted butter but did not alter the ratio of 9-cis 11-trans to total CLA. Nonfat yogurt showed an increase in CLA content with processing (5.25 mg total CLA/g fat) compared to unprocessed raw material (4.40 mg CLA/g fat). No changes in CLA content was observed in processed dairy products such as lowfat yogurt, regular yogurt, lowfat and regular ice cream, sour cream or cheeses such as Mozzarella, Gouda and Cheddar. Storage did not affect CLA concentration in any products suggesting that CLA is a stable component.
The quantities of the biologically active isomer of conjugated linoleic acid (CLA) – C18:2 c9t11 – in 139 German foods were
analysed by capillary gas chromatography (results are given as a % of all identified fatty acid methyl esters). The CLA content
ranged from 0.40% (Gouda) to 1.70% (Jurassic cheese, Old Emmentaler) in dairy products, from 0.11% (rabbit) to 1.20% (lamb)
in meat, and from 0.01% (pike-perch) to 0.09% (carp) in fish. CLA could be detected in neither vegetable fats or oils nor
in margarines (CLA <0.01%). Crisps, chocolates, cakes and pastries, and other foods have only a negligible CLA content. The
average estimated CLA intake in Germany was calculated to be 0.35g CLA/day for women and 0.43g CLA/day for men.
In the present study, the conjugated linoleic acid (CLA) contents of dairy products most consumed by the population living in the southeast region of Brazil (whole milk, “Prato” cheese and butter) were determined. In addition, the contribution of these dairy foods to the daily intake of CLA isomers was estimated. Fatty acid composition was determined by gas chromatography. Quantitative analysis of CLA isomers was done by silver-ion high-performance liquid chromatography (HPLC) and their identification was achieved by gas chromatography–mass spectrometry (GC–MS) of dimethyloxazoline (DMOX) derivatives. Eleven CLA isomers were identified and the predominant were cis-9,trans-11 and trans-7,cis-9. The total CLA contents in whole milk, “Prato” cheese and butter ranged from 4.0 to 8.4 mg/g fat and were similar to those reported for dairy products from other countries. Whole milk samples had significantly higher contents of total CLA, when compared to “Prato” cheese and butter, and the total CLA contents were significantly different between the commercial brands of each dairy product. The estimated average daily intake of total CLA in southeastern Brazil was 36 mg/day, which was lower than those of European and North American countries, and milk was the main food source of CLA in the diet.
Dairy products are major sources of conjugated linoleic acid (CLA); thus, an increase in CLA content can improve the quality value of dairy products. The objective of this work was to determine the effects of lactation time, feeding regimen, and ripening period on the level of CLA in processed cheese. CLA content in milk varied with the period of lactation; high in spring (April and May, about 6.8 mg CLA/g fat) and relatively low in mid summer and winter (about 4.3 mg CLA/g fat). The effects of dietary regimen and ripening period were determined in milk, which was obtained from March to May. After aging for 4 months, the cheese made from milk obtained from cows fed on pasture contained relatively higher levels of CLA compared to cheese made from milk obtained from cows fed indoors (8.12 mg CLA/g fat vs 6.76 mg CLA/g fat), but there was no difference in 7 month-aged cheeses. In both pasture and indoor feeding, 7 month-aged cheeses showed higher CLA content than 4 month-aged cheeses. The contents of stearic acid (C18:0) and linolenic acid (C18:3) were significantly higher in cheese from pasture fed cows compared to those in cows fed indoors. These findings should be helpful for the efficient production of functional dairy products with high CLA contents.
Extruded oilseeds were fed to 24 dairy cows to study the influence on the conjugated linoleic acid content of milk and cheese. Cows were fed one of three diets that contained forage and grain in a ratio of 47:53. A control diet containing 13.5% soybean meal was compared with diets containing 12% full fat extruded soybeans or 12% full fat extruded cottonseed. The control, extruded soybean, and extruded cottonseed diets contained 2.73, 4.89, and 4.56% fatty acids, respectively. Measurements were made during the last 5 wk of the 8-wk experiment. The DM intakes and 3.5% fat-corrected milk yields were higher for cows fed the extruded soybean and extruded cottonseed diets than for cows fed the control diet. A tendency for lower fat and protein contents in the milk of cows fed the extruded soybean and extruded cottonseed diets was detected. Most of the C18 fatty acids were increased in the milk and cheese when extruded soybeans and cottonseeds were fed. The conjugated linoleic acid content in milk and cheese increased a mean of 109% when full fat extruded soybeans were fed and increased 77% when cottonseeds were fed compared with the conjugated linoleic acid content when the control diet was fed. Processing the milk into cheese did not alter the conjugated linoleic acid content. The conjugated linoleic acid content of milk and cheese can be increased by the inclusion of full fat extruded soybeans and full fat extruded cottonseeds in the diets of dairy cows.
Conjugated linoleic acid (CLA) is a group of naturally occurring fatty acids mainly present in fats from ruminants. CLA has been shown to be a potential anticarcinogen.
In this study, the relation between bovine milk fat intake and the occurrence of CLA in human adipose tissue was investigated.
One hundred twenty-three men weighed and recorded the foods they consumed for 1 wk. Afterward, recall interviews were conducted by telephone monthly for 7 consecutive months to inquire about food consumption during the previous 24 h. The entire dietary recording procedure was repeated once. The fatty acid composition of adipose tissue and serum was analyzed.
The average amount of one isomer of CLA--9-cis,11-trans-octadecadienoic acid (9c,11t-18:2)--as a percentage of total fatty acids was found to be 0.50% in adipose tissue and 0.25% in serum. The amount of 9c,11t-18:2 in adipose tissue was significantly correlated with milk fat intake (r = 0.42). The percentage of 9c,11t-18:2 in both adipose tissue and in serum was strongly correlated with myristoleic acid (14:1).
The amount of 9c,11t-18:2 in human adipose tissue was significantly related to milk fat intake.
Dietary conjugated linoleic acid (CLA) in ruminant foods has potential health benefits. CLA content in dairy and meat products is known. However, CLA intake has not been documented from records of food intake in free-living Canadian subjects. Intake of the cis-9, trans-11-octadecadienoic acid (c9,t11 CLA) isomer was estimated for 22 free-living Canadians by analyzing two seven-day diet records taken six months apart. Intake of c9,t11 CLA did not differ between the two periods during which the food records were collected. Average intake was determined to be 94.9 +/- 40.6 mg/day ranging between 15-174 mg/day. Intake of the c9,t11 isomer of CLA when expressed as mg CLA per unit of energy consumed was significantly correlated to intake of saturated fat (r = 0.62, P < 0.002) and not significantly correlated to intake of total fat (r = 0.39, P < 0.08). Daily c9,t11 CLA intakes varied considerably with approximately 50% of the intakes falling below the 20th percentile for average level of intake per day.
Cis-9,trans-11 and trans-7,cis-9 CLA are the most prevalent CLA isomers in milkfat. The majority of cis-9,trans-11 CLA is synthesized endogenously by delta9-desaturase. We tested the hypothesis that trans-7,cis-9 CLA originates from endogenous synthesis by inhibiting delta9-desaturase with a source of cyclopropene FA (sterculic oil: SO) or with a trans-10,cis-12 CLA supplement. Experiment 1 (four cows; Latin square) involved four treatments: control, SO, partially hydrogenated vegetable oil (PHVO), and PHVO + SO. Milk, plasma, and rumen fluid were collected. Experiment 2 treatments (four cows) were 0 or 14.0 g/d of 10,12 CLA supplement; milk and plasma were collected. Samples were analyzed by GC and Ag+-HPLC to determine FA. In Experiment 1, SO decreased milkfat content of trans-7,cis-9 CLA by 68 to 71% and cis-9,trans-11 CLA by 61 to 65%. In Experiment 2, the 10,12 CLA supplement decreased milkfat content of trans-7,cis-9 CLA and cis-9,trans-11 by 44 and 25%, respectively. Correcting for the extent of treatment-induced inhibition of delta9-desaturase based on changes in myristic and myristoleic acids, endogenous synthesis of trans-7,cis-9 CLA represented 85 and 102% in Experiments 1 and 2, respectively. Similar corrected values were 77 and 58% for endogenous synthesis of cis-9,trans-11 CLA. Thus, milkfat cis-9,trans-11 CLA was primarily from endogenous synthesis with a minor portion from rumen escape. In contrast, trans-7,cis-9 CLA was not present in rumen fluid in significant amounts. Results indicate this isomer in milkfat is derived almost exclusively from endogenous synthesis via delta9-desaturase.