155 Korean J. Food Sci. Ani. Resour. Vol. 32, No. 2, pp. 155~161(2012) DOI http://dx.do.org/10.5851/kosfa.2012.32.2.155 Encapsulation of Lactic Acid in Starch by Extrusion for using as pH Regulated Binder of Meat Products Geun-Pyo Hong, Yeun-Sul Lee, Ji-Yoo Baek 1 , and Mi-Jung Choi 1 * Department of Food Science and Biotechnology of Animal Resources, Konkuk University, Seoul 143-701, Korea 1 Department of Molecular Biotechnology, Konkuk University, Seoul 143-701, Korea Abstract This study was carried out to investigate the encapsulation of lactic acid in starch matrix for the application into emulsified sausages. For the encapsulation of lactic acid in starch, the extrusion method was applied, by the different extrusion pressure level. The particle size and morphology of lactic acid containing starch granules and the rate of release of lactic acid from those granules were determined by using Mastersizer ® , a scanning electron microscopy, and electrical conductivity. The size varied slightly depending upon the extruder pressure and influenced entrapment efficiency. Lactic acid was released more slowly, when the extruder had fewer holes, which meant higher extrusion pressure, than when the extruder had more holes. Extruder pressure is therefore critical for producing finer granules that can retain lactic acid longer, during the processing of meat products. Key words: starch, lactic acid, encapsulation, extrusion, emulsified sausages Introduction During the last decade, the consumption of nutritionally enriched products has been increasing, which, along with the demand that such products be functionally enhanced, has led to great interest in encapsulation technology. The objective of encapsulation is to protect fragile substances from high temperatures, light, and other adverse condi- tions by enveloping those substances with such materials as biodegradable synthetic polymers and natural biopoly- mers, and thus maintaining the substances in stable and soluble form (Choi et al., 2009; Choi et al., 2010). Encap- sulation techniques have been developed using nano- or micro-technology to keep the encapsulated particles as small as possible, however, its application in meat prod- ucts has been limited, constrained by disadvantages such as low content of ω-3 fatty acids and by the need to ensure controlled release of acidic compounds. Bologna- type sausages supplemented with pre-emulsified polyun- saturated fatty acid (PUFA) n-3 to obtain the desired microstructure have been evaluated for their sensory attributes (Cáceres et al., 2008) and chicken meat prod- ucts prepared with fish oil and activated carbon have been evaluated for their physico-chemical characteristics (Park et al., 2002). Lactic acid, an essential ingredient of sausages, is par- ticularly critical to the final pH of the product after ripen- ing (Spaziani et al., 2008). European consumers in the Mediterranean region reject the strong acid flavors asso- ciated with quickly ripened sausages and have a predilec- tion for mildly acidic sausages. According to Pérez- Alvarez et al. (1999), the properties of lactic acid in dry- cured sausages determine the activity of the microbial flora, which comprises mostly lactic-acid bacteria. There- fore, controlled release of lactic acid during ripening is crucial to obtaining high-quality meat products. Carbohydrates such as starch or gum are generally added as fillers to increase bulk, to delay drying, to lower formulation costs, to change the texture of the product, and to make the product more stable when frozen (Hong et al., 2008; Totosausa and Pérez-Chabelab, 2009), and this use of carbohydrates has increased with the develop- ment of low-fat meat products (Choi et al., 2008, Hoe et al., 2006). Among the several forms of carbohydrates, starch is particularly suitable as a coating to encapsulate a given active substance to protect lipids from oxidation and to entrap volatile flavors (Heinemann et al., 2005; *Corresponding author: Mi-Jung Choi, Department of Molecular Biotechnology, Konkuk University, Seoul 143-701, Korea. Tel: 82-2-450-3048, Fax: 82-2-455-1044, E-mail: choimj@konkuk. ac.kr ARTICLE