Contents lists available at ScienceDirect Innovative Food Science and Emerging Technologies journal homepage: www.elsevier.com/locate/ifset Cycled high hydrostatic pressure processing of whole and skimmed milk: Effects on physicochemical properties Shuailing Yang a,1 , Guanchen Liu a,b,1 , Daniel M.E. Munk a , Zihan Qin a,c , Mikael A. Petersen a , Daniel R. Cardoso d , Jeanette Otte a , Lilia Ahrné a, ⁎ a Department of Food Science, University of Copenhagen, DK-1958 Frederiksberg C, Denmark b Hangzhou Wahaha Group, Key Laboratory of Food and Biological Engineering of Zhejiang Province, Hangzhou, China c School of Food Science and Biotechnology, Zhejiang Gongshang University, Hangzhou, China d Chemistry Institute of São Carlos, University of São Paulo, CEP 13560-470, CP 780, São Carlos, SP, Brazil ARTICLE INFO Keywords: Bovine milk Microorganism inactivation Protein modification Volatile compounds Fatty acids (FA) Nuclear magnetic resonance (NMR) ABSTRACT In this study, we compare the effects of single- and double-cycle HP treatments at 600 MPa on inactivation of the natural microflora and physicochemical properties of whole and skimmed milk of high bacterial load. The results show that two-cycled HP (2 × 2.5 min) was more effective (P < 0.05) on microbial inactivation, and caused similar or slightly less changes (P > 0.05) in physicochemical properties of milk in comparison to single cycled HP (1 × 5 min). In addition to the expected milk protein structure changes, HP at 600 MPa caused only slight effects on milk fat and lactose. Minor decreases in levels of short chain fatty acids were observed with the cycled treatments, and the volatiles in general decreased after HP treatment, depending mostly on the pressure time but also on cycling in skimmed milk. The study confirmed the superior effect of two-cycle HP on microbial in- activation, and shows a slightly better preservation of the physical-chemical milk quality. Industrial relevance: Multi-cycling HP has been shown to be advantageous for microbial inactivation, but limited information is available regarding the effect on milk components in whole milk or skimmed milk. The present study compares the psychochemical properties of whole and skimmed milk processed by multi-cycling in comparison to single cycle HP treatment. Double cycled HP presented a superior effect on microbial inactivation and slightly better preservation of milk quality than one continuous HP. 1. Introduction Consumers are demanding nutritious and fresh-like foods, and in this respect non-thermal processing technologies, such as high-pressure (HP) processing, have been shown to provide such advantages for a number of foods (Considine, Kelly, Fitzgerald, Hill, & Sleator, 2008; Knorr, 1996; Santos et al., 2019). A large number of research studies and reviews regarding the effects of HP on microorganisms, enzymes and quality properties of dairy products have been performed (e.g. Rademacher & Kessler, 1997; Trujillo et al., 2002; Van Loey, Fachin, Nguyen, Verlent, & Hendrickx, 2002; Sampedro, Rodrigo, Martínez, Rodrigo, & Barbosa-Cánovas, 2005; Voigt, Kelly, & Huppertz, 2015). From these studies it is evident that pressures from 200 to 600 MPa for up to 30 min are efficient in reduction of bacterial counts in milk. Considering industrial application, Rademacher & Kessler (1997) showed that HP treatment at 600 MPa for 3 min at 20 °C can be considered an alternative pasteurization process for raw milk. The use of HP for pasteurization of raw milk has been commercially available in Mexico since 2014, and was approved in Australia in 2016 (Han, 2016). However, in traditional supply chains, so far HP cannot fully meet the legal requirements of thermal pasteurization of milk (Patel, Carroll, & Kelly, 2016). A recent patent has reported that application of multiple cycling HP is more effective than a single HP treatment in inactivating micro- organisms in milk (Cornell, 2017). To our knowledge, only few research studies regarding multiple cycling HP treatment of milk have previously been published (Buzrul, Alpas, Largeteau, & Demazeau, 2009; Buzrul, Largeteau, Alpas, & Demazeau, 2008; García-Graells, Masschalck, Moonjai, & Michiels, 1999; Hu et al., 2015; Hu, Zheng, Liu, & Deng, 2017), and very limited information is provided about the effects of cycling HP on milk constituents. The studies of García-Graells et al. (1999) and Buzrul et al. (2008, 2009) showed that cycling HP is https://doi.org/10.1016/j.ifset.2020.102378 Received 23 December 2019; Received in revised form 7 May 2020; Accepted 9 May 2020 ⁎ Corresponding author. E-mail address: lilia@food.ku.dk (L. Ahrné). 1 The first two authors contributed equally to this work. Innovative Food Science and Emerging Technologies 63 (2020) 102378 Available online 14 May 2020 1466-8564/ © 2020 Elsevier Ltd. All rights reserved. T