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Eur. J. Lipid Sci. Technol. 2010, 112, 852858

Research Article Microencapsulation of extra-virgin olive oil by spray-drying: Inuence of wall material and olive quality Patricia Calvo, Teresa Hernandez, Mercedes Lozano and David Gonzalez-GomezTechnological Institute of Food and Agriculture (INTAEX), Junta de Extremadura, Ctra. San Vicente S/N, Badajoz, Spain

Encapsulation is a process by which small particles of core products are packaged within a wall material to form microcapsules. One common technique to produce encapsulated products is spray-drying which involves the conversion of liquid oils in the form of an emulsion into dry powders. Emulsication conditions, wall components, and spray-drying parameters have been optimized for the microencapsulation of different extra-virgin olive oils. To achieve this goal, the inuences of emulsion conditions have been evaluated for different wall components such as proteins (sodium caseinate and gelatin), hydrocolloids (Arabic gum), and hydrolyzed starches (starch, lactose, and maltodextrin). In addition, for each of the tested conditions the ratio of wall solid-to-oil and spraydrying parameters were as well optimized. The microencapsulation effectiveness was determined based on process yield and the ratio between free and encapsulated oil (microencapsulation efciency). Highest encapsulation yields were achieved when gelatin, Arabic gum and maltodextrin and sodium caseinate and maltodextrin were used as encapsulation agents and the ratio of wall solid-to-oil was 1:4 and 1:2, respectively. Under these conditions, 53% of oil was encapsulated. The inuence of olive oil quality in the microencapsulation process was evaluated in terms of fatty acids prole alteration after the microencapsulation process.Keywords: Antioxidant activity / Fatty acids / Microencapsulation / Monovarietal extra-virgin olive oil / Spray-drying

Received: February 22, 2010/ Revised: April 27, 2010/ Accepted: May 28, 2010 DOI: 10.1002/ejlt.201000059

1 IntroductionMicroencapsulation is dened as a process in which tiny particles or droplets are surrounded by a coating, or embedded in a homogeneous or heterogeneous matrix, to form small capsules [1, 2] and build a barrier between the

lez-Gomez, Instituto Tecnologico Correspondence: Dr. David Gonza Agroalimentario de Extremadura (INTAEX), Ctra. San Vicente S/N. 06007, Badajoz, Spain E-mail: david.gonzalezgo@juntaextremadura.net Fax: 34-924012674 Abbreviations: AA, antioxidant activity; ABTS, 2,20 -azinobis(3ethylbenzothiazoline)-6-sulfonic acid, diamonium salt; C2M, microencapsulated C2; FAME, fatty acid methyl esters; ME, microencapsulation efciency; MM, microencapsulated Morisca; MUFA, monounsaturated fatty acids; OSI, oxidative stability; PC, principal component; PC1, principal component 1; PC2, principal component 2; PCA, principal component analysis; PUFA, polyunsaturated fatty acids; SFA, saturated fatty acids; SSPS, soluble soybean polysaccharide; TC, total tocopherol; TPC, total phenolic compound

component in the particle and the environment. The core may be composed of just one or several ingredients and the wall may be single or double-layered. Taking into account food industry characteristics, microencapsulation should be dened as a technique by which liquid droplets, solid particle, or gas compounds are entrapped into thin lms of a food grade microencapsulating agent [2]. Although many techniques have been developed to microencapsulate food ingredients, spray-draying is the most common technology used in food industry due to low cost and available equipment. Compared to freeze-drying, the cost of spray-drying method is 30--50 times lower [3]. Microencapsulation by spray-drying has been successfully used in food industry for several decades [4] and this process is one of the oldest encapsulation methods used since the 1930s [5]. An important step in developing microcapsules is the selection of a wall material that meets the required criteria. In fact, the efciency of the protection or controlled release mainly depends on the composition and structure of the established wall. This wall could act as a barrier and it may protect against oxygen, water, light or could avoid contact with otherwww.ejlst.com

2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

Eur. J. Lipid Sci. Technol. 2010, 112, 852858

Microencapsulation of extra-virgin olive oil

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ingredients or control diffusion. The selection of wall materials for microencapsulation by spray-drying has traditionally involved trial-and-error procedures in which the microcapsules are formed. Numerous wall materials have been studied and used for their suitability as encapsulating agents in spray-drying. Walls material for microencapsulation of oil by spray-drying must have emulsifying properties, high water solubility, low viscosity, and drying properties [610]. Typical wall materials include proteins (sodium caseinate, whey proteins, soy proteins, and gelatin) and hydrocolloids (modied starch and Arabic gum). Hydrolyzed starches (glucose, lactose, corn syrup solids, and maltodextrin) are generally added as a secondary wall material to improve drying properties of sprayed droplets [7, 9]. Most edible oils are chemically unstable and susceptible to oxidative deterioration, especially when exposed to oxygen, light, moisture, and temperature. That oxidative degradation result in a loss of nutritional quality and a development undesired avors, affecting shelf stability and sensory properties of the oil [11]. Therefore, oil encapsulation may be useful to retard lipid auto-oxidation and increase the range of applications where otherwise oil could not be used. Apart from that, it has been widely reported, that the production of monovarietal olive oils has increased during the last few years due to their favorable chemical and sensorial characteristics [1219]. Among other factors, the abundance of mono-unsatured and poly-unsatured fatty acids, such as oleic acid, provide a high range of health benecial characteristics to olive oil [16]. Avoiding fatty acids prole alteration, through a microencapsulation process, will prevent loosing such healthy properties of olive oil and increase self life during product manufacturing. In this paper, we have studied for the rst time, the effect of different extra-virgin olive oil (Morisca and Picual monovarietal-type extra-virgin olive oil and three blend-type extra-virgin olive oils) in the microencapsulation process by spray-drying. Fatty acid composition has been evaluated for the different extra-virgin olive oil after and before the microencapsulation process in order to evaluate the olive oil attitude to the spray-drying processing. Furthermore, the main phytocompounds, such as phenolic compounds and tochopherol contents, antioxidant activity (AA) and oxidative stability (OSI) have been studied for each studied oils. Different aspect of microencapsulation process; such as wall material composition, wallcore micropasules ratio, microencapsulation efciency (ME) were as well evaluated.

experimental elds to ensure the monovarietal characteristic of the studied oils. The other three studied olive oils were blend-type extra-virgin olive oils bought in local groceries.

2.2 Microencapsulation wall materialSodium caseinate and starch were purchased from Sigma Aldrich (Spain). Gum Arabic and lactose were supplied by Panreac (Spain). Gelatin and maltodextrin were procured from Sancan (Spain).

2.3 Microencapsulation processThe rst stage to achieve oil microencapsulation was the formation of a ne and stable emulsion of the core material (oil) in the wall solution. Different ratios oil and wall material were evaluated for each studied wall materials. Finally, the emulsions were prepared at room temperature using a laboratory blender.

2.4 Spray-dryingThe emulsions prepared were spray dried with a laboratory scale Buchi spray drier (Mini Spray drier B-290, Buchi Labortechnik, Switzerland) equipped with 0.5 mm diameter nozzle. The pressure of compressed air for the ow of the spray was adjusted to 5 bars. The inlet and outlet air temperatures were maintained at 165 5 and 80 58C, respectively and feed rate was adjusted to 360540 mL/h. Emulsions were prepared at the moment of the spray drying process and the emulsion were kept under magnetic stirring during the whole process. The microcapsules were collected from the collecting chamber and transfer to double layer plastic bags and stored in darkness until analysis.

2.5 Microscopy and scanning electron microscopyAfter emulsion, an optical microscope (Leica DML) equipped with a digital camera (Leica DC100) was used to check the microcapsules formation and the morphology were evaluated with a scanning electron microscope.

2.6 Surface oil content and microencapsulation efficiencyTan et al. [20] modied procedure was employed to measure the amount of unencapsulated oil present at the surface of the powders. Briey, 5 g of microcapsules were precisely weighted in a beaker and 50 mL of hexane was added and shaken during 15 s at ambient temperature to extract supercial oil. The solvent mixture was then ltered throughout a lter paper, and after that, unencapsulated oil was collected after vacuum hexane evaporation. To measure the encapsulated oil, oil was extracted by 4 h Soxhlet of the same powders. After that, hexane was evaporated and internalwww.ejlst.com

2 Material and methods2.1 Extra-virgin olive oilA total of ve different extra-virgin olive oils were used in our studies. Two of them were monovarietal type extra-virgin olive oil (Picual and Morisca) and these oils were obtained in our experimental research facilities from olives harvested in 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

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Eur. J. Lipid Sci. Technol. 2010, 112, 852858

oil was scaled. ME was calculated using the following formula: ME Total oil Surface oil 100 Total oil 1

2.10 Chromatographic determination of tochopherolsA Lichrosorb Si60 column, 5 mm, 25 cm 4.60 mm id was used for the chromatographic separation of olive oil tochoperols (Agilent 1200 Liquid Chromatography equipped with a uorescence detector), being the mobile phase ow rate of 1.0 mL/min and 10 mL as the injection volume. The isocratic elution was carried out using HPLC-grade n-hexane/isopropanol/ethanol (98.5:1.0:0.5 by volume) and tocopherols were determined by using a uorescence detector with an emission wavelength of 330 nm and excitation wavelength of 290 nm. The different tocopherols were identied by comparing retention times with those of commercial standards (Merck, Spain). Results are expressed as mg/kg of oil.

Free oil content was then calculated as percentage taking into account the total oil.

2.7 Fatty acid olive oil compositionFatty acid methyl esters (FAMEs) from the oil samples were obtained by alkaline treatment with 2 N KOH in methanol and gas chromatographic analyses was carried out following the European commission regulation CEE 2568/91 [21]. To determine the alteration of fatty acids prole after the microencapsulation process (emulsion and spray draying), FAME determinations were carried out using non-processed olive oil, Soxhlet extracted of non-processes olive oil and Soxhlet extracted microencapsuled olive oil. All the analysis were performed in an Agilent 7890A Gas Chromatographer equipped with an FID detector. Fatty acids were separated in a 60 m cis/trans FAME column.

2.11 Oxidative stabilityAn 743 Rancimat (Metrohm, Switzerland) eight-channel OSI instrument was used to evaluate the OSI of the studied olive oils. The OSI index was expressed in h (n 4).

2.12 Statistical analysisThe results are expressed as means SD and were analyzed using a one-way analysis of variance (ANOVA). When ANOVA detected signicant differences between mean values, means were compared using Tukeys test. Correlations between the studied parameters were evaluated with the Pearson test at p