**Table 3.**

*Biochemistry and Health Benefits of Fatty Acids*

many samples with a good cost-per-analysis ratio.

*2.4.2 Cyclic fatty acids as quality markers in meat*

eventually distinguish farmed from wild fish.

this hypothesis has never been confirmed by experimental data.

**Sample of meat N°** 

considered [63].

GC-MS method developed is relatively simple, assures a quick sample preparation, and relies on available instrumentation, thus making it suitable for the screening of

An increasing critical issue is the substitution of higher commercial valued meats by low-priced ones and the fraudulent labeling of meat species [62]. In this context, there is the need for new, fast, and reliable analytical methodologies and easily quantifiable markers to be used for meat authentication and to protect both consumers and producers from illegal substitutions. Current methods to identify the origin of species present in commercial meat are based on DNA and ELISA, but also UPLC, Raman spectroscopy, low-field NMR, and mass spectrometry have been

Fatty acids in food authentication were mainly used for the determination of the cow feeding system, which affect the milk and meat fat composition [64, 65]. Previously, many data have been collected confirming the association between the use of ensiled feeds and the presence of CPFA in the fatty profile of dairy products. As suggested by Lolli et al. [12], cyclopropane fatty acids (mainly dihydrosterculic acid) have also been detected in animal fat, especially in bovine meat fat. As results, CPFA were detected in the fatty profiles of commercial bovine meat samples but they were absent in the samples of certified meat from cows not fed with fermented forages, reflecting the same correlation observed in dairy products [10, 11, 43]. In the case of meat of other animal species (pork, pork cured meat, and chicken), results did not show the presence of cyclopropane fatty acids as shown in **Table 3**. These preliminary results suggested that CPFA might be proposed as markers of silage feedings and for the authentication of high quality costly meat whose producers declare the absence of silages in the feeding as in dairy products. Certainly, it will require the construction of a robust database of certificated meat for the feeding system. Moreover, CPFA (mainly lactobacillic acid) were recently found [12] in farmed fish. Therefore, this approach could also be extended to fish to

Regarding omega-cyclohexyl fatty acids, they have been detected [11] (mainly 11-cyclohexyl undecanoic and 13-cyclohexyl tridecanoic fatty acids) in the GC-MS fatty profile of cow milk, suggesting their presence in milk fat could represent a reliable method to evidence rumen acidosis in cows. However, as mentioned above,

Recently, they have been also identified in animal fat, mainly in meat of ruminants, especially bovine and ovine meat [14]. Preliminary data (not published) showed that omega-cyclohexyl fatty acids, combined with other fatty acids as branched chain fatty acids [41], permitted to discriminate beef from pork meat.

Commercial bovine meat 5 200–400 Bovine meat of certified origin (not fed with silages) 2 Negativea Other meats (pork and chicken) 4 Negativea Pork cured meat 3 Negativea

**sample**

**Range CPFA (mg/kg total fat)**

**42**

*a*

**Table 3.**

*<LOD (60 mg/kg total fat) [12].*

*Presence of CPFA in meat samples.*

As suggested by Marseglia et al. [11], 11-cyclohexyl undecanoic fatty acid methyl ester from milk and meat fat eluted in the chromatographic region of isomers of the oleic acid, so it was detected by the characteristic molecular ion 282 m/z in the mass spectrum.

13-cyclohexyl tridecanoic fatty acid methyl ester was detectable in the GC-MS profile as it elutes just before the eicosanoic acid (arachidic acid) and after eicosenoic acid. However, due to the presence of interfering signals, the identification of 13-cyclohexyl tridecanoic was confirmed by the mass spectrum with the characteristic molecular ion 310 m/z and the previous biosynthesized compound [11]. The characteristic mass spectra of 13-cyclohexyl tridecanoic fatty acid detected by GC-MS analysis is shown in **Figure 5**.

The results from the GC-MS analysis showed that omega-cyclohexyl fatty acids, both 11-cyclohexylundecanoic acid and 13-cyclohexyltridecanoic acid, were present only in bovine and ovine meat samples with values between 90–230 and 20–200 mg/kg of the total meat fat, respectively [14]. On the contrary, they were absent in pork, horse, chicken, and rabbit, reflecting the ruminal origin and a possible application for the detection of bovine/pork ratio in commercial minced meat [14].

As mentioned above, current analytical methods in meat authentication are mainly based on protein or DNA measurement, which are not directly comparable to labeled meat expressed as percentage (w/w) [66]. Furthermore, analytical procedures based on protein analysis are sensitive to heat treatment. Therefore, they could not be applied to cooked products for the quantitative analysis. In this context, a quantitative GC-MS method is going to be developed on mixtures of beef and pork meat, both raw and cooked (ragout), based on the method previously applied to determine CPFA [43] and combining other fatty acids, as iso-branched chain fatty acids, of ruminal origins [41].

Preliminary results [14] showed that omega-cyclohexyl and iso-branched chain fatty acids content decreased in minced meat, both raw and cooked, as function of bovine meat percentage in the sample, as shown in **Table 4**.

Therefore, the analysis of omega-cyclohexyl fatty acids combined with that of specific iso-branched chain fatty acids was able to detect until 20% of pork meat in beef, representing potential markers for ruminant meat, also detectable in complex matrix and after thermal treatment in ragout samples.

**Figure 5.** *Mass spectra of 13-cyclohexyl tridecanoic fatty acid methyl ester [11].*

*Biochemistry and Health Benefits of Fatty Acids*


#### **Table 4.**

*Concentration (mg/kg total fat) of omega-cyclohexyl and iso-branched chain fatty acids found in minced meat, both raw and cooked (ragout), as function of bovine meat percentage [14].*

In conclusion, omega-cyclohexyl fatty acids can be proposed as markers of ruminant meat, especially of beef meat, which could enforce current analytical methods applied for labeling regulations.

### **3. Conclusions**

Cyclopropane and omega-cyclohexyl fatty acids are carboalicyclic fatty acids widely distributed among microorganisms, enhancing the chemical and physical stability of bacterial membranes. Significant variations in the membrane content of cyclic fatty acids have been identified in a multitude of physiological situations. Recently, they have been detected in food of animal origins, so representing new components in human diet. In some cases, these cyclic fatty acids can act as markers of quality and their detection could enforce current analytical methods adopted in food authentication.

However, little is known regarding the actual role that these fatty acids play, their release, and the chemical basis of their effects on the cellular membrane, especially in higher animals.

**45**

**Author details**

provided the original work is properly cited.

Augusta Caligiani\* and Veronica Lolli

*Cyclic Fatty Acids in Food: An Under-Investigated Class of Fatty Acids*

We declare that we have no conflict of interest.

*DOI: http://dx.doi.org/10.5772/intechopen.80500*

**Conflict of interest**

© 2018 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

Department of Food and Drug, University of Parma, Parma, Italy

\*Address all correspondence to: augusta.caligiani@unipr.it

*Cyclic Fatty Acids in Food: An Under-Investigated Class of Fatty Acids DOI: http://dx.doi.org/10.5772/intechopen.80500*
