ESSENTIAL OILS AS ANTIOXIDANTS FOR FATLIQUORING EMULSION

Transcription

1 ICAMS th International Conference on Advanced Materials and Systems ESSENTIAL OILS AS ANTIOXIDANTS FOR FATLIQUORING EMULSION VIRGILIJUS VALEIKA, JUSTA ŠIRVAITYTĖ, KESTUTIS BELEŠKA, VIOLETA VALEIKIENĖ Kaunas University of Technology, Radvilenu pl. 19, Kaunas LT-50254, Lithuania Oxidation can change the properties of fatliquoring emulsion components. For leather fatliquoring are used natural fats or oils, and their recycling products, petrol chemicals products, synthetic fats, oil or soaps. These materials are more or less sensitive to oxidation process. Therefore, for the increase of their stability could be used antioxidants. For sample, polyphenols from plant extracts have been used in different food matrices to improve the oxidative stability of lipids. In the presented material were proposed commercial essential oils of Lavandulae officinalis and Eucalyptus globulus as antioxidants for fatliquoring system assigned to tanned leather. It was established that selected essential oils have different extent of antioxidant activity. The commercial essential oils of Eucalyptus globulus has shown close antioxidant activity comparing with butylated hydroxytoluene. The addition of essential oil into leather fatliquoring emulsion has negligible influence on tanned leather quality indexes. Keywords: essential oil, antioxidant, fatliquoring INTRODUCTION Depending on the storage conditions, two main reactions can affect lipids. Oxidation is a free radical chain process occurring spontaneously or at moderate temperatures in the presence of molecular oxygen. Although the reaction between triplet oxygen and fatty acids is thermodynamically unfavourable (Frankel, 2005), heat, transition metals, and light can accelerate fatty acid free radical formation (Choe et al., 2006). Under light exposure in the presence of sensitizers such as metals or chlorophylls, triplet oxygen can form singlet oxygen, a powerful radical generator that reacts directly with lipids (Choe et al., 2006). The oxidation can change the fatliquoring emulsion compounds properties. For leather fatliquoring are used natural fats or oil, their recycling products, petrol chemicals products, synthetic fats, oil or soaps. These materials are more or less sensitive to oxidation process (Covington, 2009). Leather fatliquoring process is carried out at 55-60ºC temperature which could also attributed to the lipids oxidation condition. Therefore, for the stop of this process run the antioxidants could be employed. Many sources of antioxidants of a plant have been studied in recent years. Many aromatic plants and spices have been shown to be effective in retarding the process of lipid peroxidation (Kulisic et al., 2004). One component present in aromatic plants and spices, and which may act as a natural antioxidant, is the corresponding essential oil. Polyphenols from plant extracts have been used in different food matrices to improve the oxidative stability of lipids (Boroski et al., 2012). In this case authors propose natural materials such as Lavandulae officinalis and Eucalyptus globulus essential oils. In previous research was concluded that following essential oils could be used in leather tanning as antimicrobial agents (Sirvaityte et al., 2011). The aim of this research was to investigate antioxidant properties of Lavandulae officinalis and Eucalyptus globulus essential oils.

2 Essential Oils as Antioxidants for Fatliquoring Emulsion MATERIALS AND METHODS For investigation was used rapeseed oil. As control antioxidant was used butylated hydroxytoluene (BHT) and 2,2-diphenyl-1-pikryl-hydrazyl (DPPH) (Sigma Chemicals, USA). Others chemicals were analytical grade. The essential oils of company Meta (Lithuania) were used for experiments. There were commercial essential oils of Eucalyptus globulus (EO) and Lavandulae officinalis (LO). Cured by salting bovine hides were used in order to obtain chromed leather. The processes were carried out according to the conventional technologies. For the experiments, tanned with chromium leather samples were neutralized and fatliquored under conditions described in Figure 1. Figure 1. Leather neutralization and fatliquoring conditions (% from wet-blue mass) Neutralization a) H 2 O 150%; NaHCO 3 1.5%; temperature 35 40ºC; duration 0.5 h; run continuously; b) HCOONa 2.0%; duration 1.5 h; run continuously; (ph of leather ~ 5.6) Washing H 2 O 100%; temperature o C; duration 30 min; run continuously. Fatliquoring a) H 2 O 150%; Coripol GF 10.0%; Coripol A 4.0%; Borron SAF 0.2%; essential oil 1%; temperature o C; duration 1.5 h; run continuously; b) HCOOH 1%; duration 0.5 h; run continuously; (ph of leather ~ 4.0) Washing H 2 O 100%; temperature 30 o C; duration 0.5 h; run continuously. The products of TFL Holding GmbH (Germany) were used: Coripol GF is oil based on a combination of selected natural and synthetic fatty substances; Coripol A is viscous oil based on natural phospholipids; Borron SAF is a clear product, based on sulphated fatty alcohols. The control samples of leather were tanned according to the conventional technology of Joint-stock company Kedainiu oda. Determination of Radical Scavenging in DPPH Reaction The antioxidant activity of essential oils was measured using DPPH radical scavenging assay method (Brand-Williams et al., 1995). The 5 ml methanol solution of DPPH was used. The reaction was started by the addition of 25 ml sample and the decrease in absorbance was measured on a Beckman DU-650 spectrophotometer at 515 nm after 16 min and 2 h. Methanol was used as a blank sample. All determinations were performed in triplicate. The antioxidant activity was calculated as the inhibition (%) of the DPPH radical. Peroxide Value Primary oxidation products hydroperoxides were determined by peroxide value measurements. 1±0.1 g of oil was weighted and subjected to iodometric

3 ICAMS th International Conference on Advanced Materials and Systems determination of peroxide value (AOCS, 1990). The induction period was considered as the number of days needed for the peroxide value of the sample to become 20 meq O 2 /kg of fat. This is in agreement with a general consideration that oils become rancid at peroxide value higher than 20. Leather Quality Indexes The amount of chrome compounds in leather was determined by method described in literature (Standard ISO, 2007). The shrinkage temperature of leather was measured with a special instrument (Golovteeva et al., 1982). The matter soluble in dichloromethane and free fatty acid content were determined according to standard (Standard ISO, 2008). Statistical Analysis All data were expressed as the mean ± standard error of triplicate measurements. Confidence limits were set at P < Standard deviations did not exceed 5% for the majority of the values obtained. RESULTS AND DISCUSSIONS The DPPH free radical does not require any special preparation and is considered a simple and very fast method for determining antioxidant activity. So, this method was chosen for estimation of antioxidant activity of commercial essential oils. The obtained data (Table 1) show that antioxidant activity of essential oils increases when increasing their concentration. Also, here could be mentioned that initially LO showed the higher radical scavenging effect comparing with EO. This could be explained by the earlier received results, which had shown that LO contained more phenolic compounds than EO (Sirvaityte et al., 2011). The IC50 of LO was 230 μl/ml (Table 1) and 394 μl/ml in the case of EO (Table 2 ) (the IC50 is the amount of essential oil needed for 50% inhibition of free radicals.). However, in the course of time the essential oil of Eucalyptus antioxidation capacity increases almost up to 100% during 120 min. LO also has shown the high efficiency, but during storage antioxidative activity reaches only 78%. Table 1. Antioxidative capacity of the Lavandulae officinalis essential oil Concentration of Time, min essential oil, μl/ml

4 Essential Oils as Antioxidants for Fatliquoring Emulsion Table 2. Antioxidative capacity of the Eucalyptus globulus essential oil Concentration of Time, min essential oil, μl/ml To simulate the fatliquoring material the selected essential oil had been mixed with rapeseed oil and peroxide value determined (Table 3). For the experiment were prepared mixtures from rapeseed oil with essential oils or with BHT. The amount of essential oils added into rapeseed oil was 1%. The amount of antioxidant agent BHT was standard and was 0.02% from rapeseed oil mass. As control was used pure rapeseed oil without any additives. As the temperature of fatliquoring usually is C, the samples are kept 45 days at 55 C temperature. The results presented in Table 3 show that pure rapeseed oil (control sample) reaches 20 meq O 2 /kg during 21 day. In case of LO addition this value was reached during 21 days. EO stops oil oxidation process better and its effect is close to the effect obtained with the use of BHT. Therefore, LO in mixture with rapeseed oil has shown better antioxidant activity after one hour of storage at C temperature, but after 72 hours of storage it becomes less comparing with EO. So, the obtained results approve the trend obtained measuring the antioxidant activity of the separate essential oils (Tables 1 and 2). Table 3. Peroxide value (meq O 2 /kg) alteration of samples Used antioxidant Duration, h agent control BHT LO EO To evaluate the influence of essential oils on leather properties, such indexes as shrinkage temperature, content of Cr 2 O 3, matter soluble in dichloromethane and content of moisture were determined. The chromed leather samples were fatliquored (under conditions described in Figure 1) with emulsion, which contains LO (2 nd sample) and EO (3 rd sample). The received results were compared with leather tanned according to conventional method (1st sample) in manufactory. The data are presented in Table 4.

5 ICAMS th International Conference on Advanced Materials and Systems Table 4. Quality indexes of leather after fatliquoring Index of chromed leather Sample No. Shrinkage temperature, ºC Content of Cr 2 O 3, % Matter soluble in dichloromethane, % Content of moisture, % 1 st (control) nd rd The shrinkage temperature of leather tanned in manufactory is slightly higher but it can be expected because all processes run better under the industrial conditions. Also, it could be mentioned that higher content of fats was in samples processed using EO (16.3%). CONCLUSIONS The result of the present study showed that the commercial essential oil of Eucalyptus globulus and Lavandulae officinalis, which contain high amount of phenolic compounds, exhibited antioxidant activity. Selected essential oils have different extent of antioxidant activity. The commercial essential oil of Eucalyptus globulus has shown close antioxidant activity compared to butylated hydroxytoluene. The addition of essential oils into leather fatliquoring emulsion has negligible influence on tanned leather quality indexes. REFERENCES AOCS (1990). In: Official methods and recommended practices of the American Oil Chemists' Society Method Cd 8-53 and Method Cd (4th ed.). Champaign: American Oil Chemists' Society. Boroski M., Giroux H. J., Sabik H., Petit H.V., Visentainer J.V., Matumoto-Pintro P.T., Britten M. (2012), Use of oregano extract and oregano essential oil as antioxidants in functional dairy beverage, Food Science and Technology, 47(1), Brand-Williams, W., Cuvelier, M.E. and Berset, C. (1995), Use of a free radical method to evaluate antioxidant activity, Lebensmittel-Wissenschaft und -Technologie/Food Science and Technology, 28, Choe E, Min D. B. (2006), Mechanisms and factors for edible oil oxidation, Comprehensive Reviews in Food Science and Food Safety, 5, Covington A.T. (2009), Tanning Chemistry The Science of Leather. The Royal Society of Chemistry, Cambridge. Economou K.D., Oreopoulou V., Thomopoulos C.D. (1991), Antioxidant activity of some plant extracts of the family Labiatae, Journal of American Oil Chemists' Society, 68, Frankel, E.N Lipid Oxidation, Second Edition, The Oily Press, Bridgwater, England. Golovteeva A., Kutsidi D., Sankin L. (1982), Laboratornyj praktikum po khimiyi i tekhnolo giyi kozhy i mekha, Legkaiya i Pischevaiya Prom, Moscow (Russ.). Kulisic, T., Radonic, A., Katalinic, V., Milos, M. (2004). Use of different methods for the testing activity of oregano essential oil. Food Chemistry, 85, Sirvaityte J., Siugzdaite J., Valeika V. (2011), Application of Commercial Essential Oils of Eucalyptus and Lavender as Natural Preservative for Leather Tanning Industry, Revista de Chimie, 62(9), Standard ISO :2007. Leather Chemical determination of chromic oxide content Part 1: Quantification by titration. Standard ISO 4048:2008. Leather Chemical tests Determination of matter soluble in dichloromethane and free fatty acid content.

6 Essential Oils as Antioxidants for Fatliquoring Emulsion