Land Snails As a Valuable Source of Fatty Acids: a Multivariate Statistical Approach
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foods Article Land Snails as a Valuable Source of Fatty Acids: A Multivariate Statistical Approach Francesco Giuseppe Galluzzo 1 , Gaetano Cammilleri 1,2,* , Alessandro Ulrici 2 , Rosalba Calvini 2, Andrea Pulvirenti 2 , Giovanni Lo Cascio 1 , Andrea Macaluso 1,2, Antonio Vella 1, Nicola Cicero 3 , Antonella Amato 4 and Vincenzo Ferrantelli 1,2 1 Istituto Zooprofilattico Sperimentale della Sicilia, via Gino Marinuzzi 3, 90129 Palermo, Italy; [email protected] (F.G.G.); [email protected] (G.L.C.); [email protected] (A.M.); [email protected] (A.V.); [email protected] (V.F.) 2 Dipartimento di Scienze della Vita, Università degli studi di Modena e Reggio Emilia, Via Università 4, 41121 Modena, Italy; [email protected] (A.U.); [email protected] (R.C.); [email protected] (A.P.) 3 Dipartimento SASTAS, Università degli studi di Messina, Polo Universitario dell’Annunziata, 98168 Messina, Italy; [email protected] 4 Dipartimento di Scienze e Tecnologie Biologiche Chimiche e Farmaceutiche, Università degli Studi di Palermo, Viale delle Scienze, 90128 Palermo, Italy; [email protected] * Correspondence: [email protected]; Tel.: +39-328-8048262 Received: 4 November 2019; Accepted: 5 December 2019; Published: 12 December 2019 Abstract: The fatty acid (FA) profile of wild Theba pisana, Cornu aspersum, and Eobania vermiculata land snail samples, collected in Sicily (Southern Italy), before and after heat treatment at +100 ◦C were examined by gas chromatography with a flame ionization detector (GC-FID). The results show a higher content of polyunsaturated fatty acids (PUFAs) in all of the examined raw snails samples, representing up to 48.10% of the total fatty acids contents, followed by monounsaturated fatty acids (MUFAs). The thermal processing of the snail samples examined determined an overall reduction of PUFA levels (8.13%, 7.75%, and 4.62% for T. pisana, C. aspersum and E. vermiculata samples, respectively) and a species-specific variation of saturated fatty acid (SFA) contents. Oleic acid remained the most abundant FA of all of the snails species examined, accounting for up to 29.95% of the total FA content. A relevant decrease of Ñ3/Ñ6 ratio was found only for T. pisana samples. The principal component analysis (PCA) showed a separation of the snail samples in terms of species and heat treatment. The results of this work suggest land snails as a valuable source of MUFA and PUFA contents and boiling as appropriate treatment, according to the maintenance of healthy properties. Keywords: fatty acids; land snails; GC-FID; heat processing; principal component analysis 1. Introduction Terrestrial gastropods, commonly named land snails, constitute a niche food product traditionally appreciated by many European countries, especially France and Italy. The use of land snails as food is still steadily growing, and 26,000 tons of snails were imported from Africa and countries in the Middle East [1]. Cornu aspersum, Eobania vermiculata, and Theba pisana are the land snail species most consumed in Italy [2]. Land snails are consumed in different ways all over the world, but the principal cooking procedures recognized are roasting and boiling, according to the traditions of the countries. According to Milinsk et al. [3], there is a correlation between land snails’ diet and their nutritional values. Recently, increasing attention was paid to the fatty acid composition, due to nutritional and health-related aspects [4–8]. However, few studies are available about the fatty acid (FA) profile in Foods 2019, 8, 676; doi:10.3390/foods8120676 www.mdpi.com/journal/foods Foods 2019, 8, 676 2 of 10 due to nutritional and health-related aspects [4–8]. However, few studies are available about the fatty Foods 2019, 8, 676 2 of 10 acid (FA) profile in land snails [3,9,10] and, as far as we know, no data have been reported regarding the fatty acid profile of T. pisana. Snails are commonly consumed in different ways after boiling due to landthe risk snails posed [3,9 by,10 ]the and, possible as far aspresence we know, of potentially no data have pathogenic been reported microorganisms regarding the [2] fatty. The acid cooking profile temperatureof T. pisana can. Snails influence are commonly the nutritional consumed aspect in of di mollusksfferent ways [11] after. At present, boiling due there to are the too risk few posed studies by the aboutpossible the influence presence of potentiallyheat processing pathogenic (such as microorganisms boiling) on the [ 2nutritional]. The cooking composition temperature of land can influencesnails. theIn nutritional this context, aspect the ofpresent mollusks work [11 aimed]. At present,at evaluating there arethe toofatty few acids studies content about of thewild influence C. apsersum of heat, T. processingpisana, and (such E. vermiculata as boiling) samples on the nutritionalcollected in composition Sicily (Southern of land Italy). snails. Furthermore, the effect of boiling Inon this the context,fatty acid the composition present work was aimed evaluated at evaluating to have thea comprehensive fatty acids content nutritional of wild evaluationC. apsersum , of T.this pisana, productand afterE. vermiculata processing.samples collected in Sicily (Southern Italy). Furthermore, the effect of boiling on the fatty acid composition was evaluated to have a comprehensive nutritional evaluation of 2. Materialsthis product and after Methods processing. 2.1.2. Reagents Materials and and Standards Methods 2.1.All Reagents chemicals, and Standardssolvents, and reagents employed were of analytical grade (≥99.9%). Acetone, hexane, diatomaceous earth, sodium sulfide nonahydrate, methanol, and hydrochloric acid were All chemicals, solvents, and reagents employed were of analytical grade ( 99.9%). Acetone, purchased from Sigma-Aldrich (Amsterdam, Holland). All of the gas used for gas chromatography≥ (GChexane,) analysis diatomaceous was pure (≥99.9995%). earth, sodium Water sulfide used nonahydrate, for the separation methanol, of andfatty hydrochloric acid methyl acid esters were (FAMEspurchased) phase from was Sigma-Aldrich bidistilled in (Amsterdam, Milli-Q® Integral Holland). 5 (Merck All of KGaA, the gas usedDarmstadt, for gas Germany). chromatography FA standards(GC) analysis were waspurchased pure ( from99.9995%). Sigma Water-Aldrich used (Amsterdam, for the separation Holland). of fatty The acid 10,000 methyl mg/L esters standards (FAMEs) ≥ ® werephase prepared was bidistilled by diluting in Milli-Q100 mg ofIntegral a pure 5standard (Merck KGaA,solution Darmstadt, with 10 ml Germany). of n-hexan FAe. A standards mixture wereof FApurchased standards fromwas used Sigma-Aldrich for the identification (Amsterdam, of Holland).each peak. The 10,000 mg/L standards were prepared by diluting 100 mg of a pure standard solution with 10 ml of n-hexane. A mixture of FA standards was 2.2.used Sample for theCollection identification and Preparation of each peak. 2.2.A Sampletotal of Collection 128 samples and of Preparation C. aspersum, 400 samples of T. pisana, and 162 samples of E. vermiculata, were collected from Palermo provinces (Sicily, Southern Italy) in 2018 during July for C. aspersum, A total of 128 samples of C. aspersum, 400 samples of T. pisana, and 162 samples of E. vermiculata, August for T. pisana, and September for E. vermiculata to have the maximum assimilation efficiency were collected from Palermo provinces (Sicily, Southern Italy) in 2018 during July for C. aspersum, according to the literature [12–14]. The shell of the snail samples was removed and only the meat was August for T. pisana, and September for E. vermiculata to have the maximum assimilation efficiency considered for the chemical analysis. The meat of the snail samples was grouped into three pools according to the literature [12–14]. The shell of the snail samples was removed and only the meat was according to the species, then homogenized by a vertical mixer B-400 (Büchi, Flawil, Switzerland) considered for the chemical analysis. The meat of the snail samples was grouped into three pools and stored at −10 °C for 24 h to prevent a decrease in fatty acid content during the storage period [15]. according to the species, then homogenized by a vertical mixer B-400 (Büchi, Flawil, Switzerland) and The FA content of each sample pool was determined both raw and after cooking at 100 °C with boiled stored at 10 C for 24 h to prevent a decrease in fatty acid content during the storage period [15]. water for 30− s. The◦ entire procedure of analysis is shown in Figure 1. The FA content of each sample pool was determined both raw and after cooking at 100 ◦C with boiled water for 30 s. The entire procedure of analysis is shown in Figure1. Figure 1. Scheme of the cooking process of the land snails samples collected. 2.3. Extraction of Fatty Acids and Gas Chromatography with a Flame Ionization Detector (GC-FID) Analysis Figure 1. Scheme of the cooking process of the land snails samples collected. An amount of 10 0.1 g of each pool of samples was placed in a glass of polypropylene and ± mixed with diatomaceous earth (Sigma-Aldrich, Amsterdam, Holland). The mixture was transferred in Foods 2019, 8, 676 3 of 10 an accelerated solvent extraction (ASE) ASE 200 cell (Thermo Fisher, Waltham, Massachusetts, USA). The ASE operating conditions were set up as follows: 20 mL of hexane/acetone, 70:30; extraction temperature 120 ◦C for 6 min with a pressure of 120 pound per square (PSI). The extract was filtered (size 240 nm) and dehydrated in rotavapor (Büchi, Flawil, Switzerland) at +40 ◦C. For the preparation of FAME, 100 mg of the oil extracted was trans-esterified in a pyrex tube by using 2 mL of HCl/MeOH (2:98 v/v) to obtain the fatty acid methyl esters (FAMEs). The solution was mixed in a vortex for 1 min and put in the oven at 120 ◦C for 1 h.