Treatment of milk fat with sn-2 specific Pseudozyma antarctica lipase A for targeted hydrolysis of saturated medium and long-chain fatty acids Antti Nyyss € ol € a a , Hanna Miettinen a , Hanna Kontkanen a, 1 , Martina Lille a , Riitta Partanen a , Susanna Rokka b , Eila J € arvenp € a € a b , Raija Lantto a , Kristiina Kruus a, * a VTT Technical Research Centre of Finland, P.O. Box 1000, FIN-02044 VTT, Finland b MTT Agrifood Research Finland, FI-31600 Jokioinen, Finland article info Article history: Received 9 April 2014 Received in revised form 19 September 2014 Accepted 21 September 2014 Available online 5 October 2014 abstract Milk fat was treated with the sn-2 specific PAN-2 lipase from Pseudozyma antarctica with the aim of achieving selective removal of saturated fatty acids with chain lengths between C12 and C16, which are abundant at the sn-2 position. Hydrolysis was also carried out using the non-specific CRU-NS from Candida rugosa and the 1,3-specific TLA-1,3 from Thermomyces lanuginosus. PAN-2 treatment decreased the proportion of the target fatty acids considerably (content of 28%, w/w) and increased the proportion of unsaturated ones (content of 52%, w/w) at the degree of hydrolysis of 48% (mol/mol) in relation to the unhydrolysed substrate (47%, w/w, C12:0-C14:0 and 32%, w/w, unsaturated). The fatty acid distributions of the TLA-1,3 and CRU-NS treated samples were similar to untreated milk fat. The proportion of crys- talline fat was smaller and the firmness lower in the PAN-2 treated milk fat samples than in the un- treated milk fat at 5  C. © 2014 Published by Elsevier Ltd. 1. Introduction Fatty acid composition of cows' milk fat varies depending upon feeding practises, season and cattle breed. It can, however, be estimated that roughly 40% (w/w) of fatty acids in milk fat are saturated with chain lengths of C12 to C16 (lauric, myristic and palmitic acid). Stearic acid (C18:0) and unsaturated fatty acids (mostly oleic acid, C18:1) account for 12% and 25% of the total, respectively. Around 10% of the milk fat fatty acids are saturated short-chain (C4:0-C10:0) (German & Dillard, 2006). It is widely believed that increased intake of saturated fat is linked with higher cardiovascular disease risk in humans. Reducing dietary saturated fat, including milk fat, is hence recommended by many nutritional authorities around the world (Davis et al., 2010). Because of a lack of convincing evidence, a positive correlation between milk fat intake and cardiometabolic risk has, however, come under dispute (Kratz, Baars, & Guyenet, 2013). Cows' milk fat is a complex mixture, and in addition to saturated middle and long- chain fatty acids, it contains many other components, for example, various long-chain unsaturated fatty acids that are believed to be beneficial for cardiovascular health. It has been suggested that the bioactive components present in milk fat may counter the negative effects of saturated fatty acids on cardiovascular health (Huth & Park, 2012; Kratz et al., 2013). However, the general view on fatty acids per se is that replacing saturated fatty acids with unsaturated ones leads to improved health and reduced risk for atherosclerosis (Huth & Park, 2012; Jakobsen et al., 2009; Mensink, Zock, Kester, & Katan, 2003). Longer saturated fatty acids, such as stearic acid (C18:0), are believed to be neutral in terms of heart disease risk (German & Dillard, 2006; Hunter, Zhang, & Kris-etherton, 2010). Saturated short chain fatty acids are not considered to present health risks but they have been reported to have antitumour (C4:0) and antiviral (C6:0-C10:0) activities as well as gut health promoting properties (C6:0) (Burton, 1991; Isaacs, Litov, & Thormar, 1995; Neyts, Kristmundsd ottir, De Clercq, & Thormar, 2000; Parodi, 1997; Segain et al., 2000). Milk fat consists mostly of triglycerols with only minor amounts of diglycerols present (German & Dillard, 2006). Clinical research data indicate that consumption of diglycerol oil reduces weight gain, which is most likely a result of increased fat oxidation, leading to better appetite control (Flickinger & Matsuo, 2003; Kamphuis, Mela, & Westerterp-Plantenga, 2003). In conclusion, the research on the health effects of milk fat components suggests that diglycerol-rich milk fat product with a heightened content of * Corresponding author. Tel.: þ358 50 520 2471. E-mail address: kristiina.kruus@vtt.fi (K. Kruus). 1 Present address: Valio Ltd. Research and Development Centre, FIN-00039 Valio, Finland. Contents lists available at ScienceDirect International Dairy Journal journal homepage: www.elsevier.com/locate/idairyj http://dx.doi.org/10.1016/j.idairyj.2014.09.003 0958-6946/© 2014 Published by Elsevier Ltd. International Dairy Journal 41 (2015) 16e22