Quality of Norwegian goat milk for cheese production Kvalitet på norsk geitemelk til osteproduksjon Philosophiae Doctor (PhD) Thesis Ragnhild Aabøe Inglingstad Department of Chemistry, Biotechnology and Food Science Faculty of Veterinary Medicine and Biosciences Norwegian University of Life Sciences Ås 2016 Thesis number 2016:19 ISSN 1894-6402 ISBN 978-82-575-1348-1 Contents Acknowledgements ............................................................................................................................................ 2 Summary ............................................................................................................................................................ 5 Sammendrag ...................................................................................................................................................... 7 Abbreviations ..................................................................................................................................................... 9 List of papers .................................................................................................................................................... 10 1. Introduction ................................................................................................................................................. 13 1.1 Milk in human nutrition – a historical perspective ................................................................................. 13 1.2 The Goat and its milk .............................................................................................................................. 14 1.3 Norwegian goats and milk production .................................................................................................... 15 1.4 Milk composition and technological parameters .................................................................................... 17 1.5 Challenges and strategies to improve Norwegian goat milk quality ....................................................... 25 2. Background for the project “Quality goat milk for cheese production” and aims of current study .... 29 3. Experimental design .................................................................................................................................... 30 4. Summary of papers...................................................................................................................................... 33 5. Key results and general discussion ............................................................................................................. 39 5.1 Goats on pastures - effects in milk .......................................................................................................... 39 5.2 Lipid supplements – effects in milk ........................................................................................................ 42 5.3 Polymorphism at the αs1 -casein locus- effects in milk ............................................................................ 44 5.4 Factors influencing the rennet coagulation properties in Norwegian goat milk ...................................... 45 5.5 Factors influencing the level of FFA in Norwegian goat milk ................................................................ 46 6. Current status, concluding remarks and further perspectives ................................................................ 49 7. References..................................................................................................................................................... 50 8. Enclosed papers I-V ..................................................................................................................................... 60 1 Acknowledgements Financial support for this thesis was provided by the Norwegian Research Council and TINE (Norwegian Dairies Association). First, I would like to thank my main supervisor, Gerd Vegarud, for giving me the opportunity to become a PhD student and your never-ending support. Your encouragement and gentle “pushes” have been highly valued! I would also express my gratitude to my co-supervisors Siv Skeie, Tove Devold and Margrete Eknæs: Siv Skeie, thank you for your great interest and overview in this project, and your considerable contribution to my work and studies. Tove Devold, your door is always open, and you are always up for a discussion. Thank you for your time and support whenever needed. Margrete Eknæs, thank you for a nice cooperation with the feeding experiment, and for sharing your great knowledge about feeding and physiology of goats. You did all guided me in scientific writing (and thinking) and you were always supporting me even if I sometimes failed. I was very fortunate to have this nice team of supervisors! Further, I am very grateful to all those involved in the project “Quality goat milk for cheese production”. Thank you for sharing your great knowledge about various factors influencing the milk quality. I would especially like to thank Håvard Steinshamn for the great collaboration with the Gibostad pasture project, and for your contribution to the two papers we wrote together. I really learned a lot from you! Elling Rukke, I appreciate your good and specific advices regarding both the experimental design and in writing manuscripts and for being my co-supervisor for a while. Lise Brunborg, I am so happy that you joined us and did the work for your master degree related to this project. The cheesemaking really added something to the study. Thank you for some joyful months when we shared office. I am very grateful to Tormod Ådnøy, for excellent leadership of the project, for sharing of your great knowledge about breeding and for supplying me with old articles, conference proceeding etc. Binyam Dagnachew, I am thankful for all the fruitful discussion regarding genotypes, SNPs, breeding, PCA, and for patiently explaining FTIR prediction and additive and dominance effects repeatedly… I would like to express my gratitude to all the co-authors, for your valuable comments and discussions regarding the papers. I am especially grateful to Yves Chilliard for sharing his great knowledge about LPL, lipolysis and effects of lipid feeding. Andrea Criscione and 2 Bernardo Valenti are acknowledged for their contribution in quantification of individual caseins and for valuable discussions. Knut Erik Grindaker, thank you for sharing your knowledge about rennet coagulation properties and FFA of the Norwegian goats! And for being in charge of the sensory evaluation of each and every milk sample in the 2011 experiment together with Helga Kvamsås and Kåre Joahn Vassbotn. I am also thankful to the staff at Distriktslaboratoriet Brumunddal for analysing the samples at specific time points and providing the results of the routine milk analysis. During the experimental periods, there were loads of milk samples that required immediately analysis and/or preparation. I was unable to take care of all of them alone, and I am very thankful for the assistance of: Irene Comi in milk sampling and distribution, Claes-Gøran Fristedt for measuring milk fat globules, Mestawet Taye Asfaw for protein and casein analysis, May Aalberg for shipping of milk samples and in protein analysis, Ida Block for measuring calcium content, Tone Molland, Thor Bruun, Bjørg Holter and my supervisors for extra assistance in the lab whenever needed. Dag Ekeberg, Hanne Devle and Kristi Ekrann Aarak are acknowledged for valuable discussions and tips regarding identification and quantification of fatty acids, and Kari Olsen for supervising in identification and analysis of fatty acids by GC-FID. Magnhild Nymo and Agnes Koulman and other staff members at Gibostad vgs and Animal Production Experimental Centre of NMBU are acknowledged for great care of the goats and assistance in milk sampling. Thanks to past and present fellow PhD-students, master students, post docs, researchers and colleges for coffee or tea breaks, scientific and non-scientific talks, for sharing ups and downs and making a nice working environment. Too many to be named one by one, you know who you are! I am especially thankful for the friendship of three special colleges: Mestawet, Ellen and Irene. Thank you for being there for me and for being you . Thanks to all my good friends for always cheering on me, and to my dearest sisters for all kinds of support: milk sampling at the mountain pasture, proof reading of tables and texts, babysitting, taking care of my horses… Mum and dad, being a PhD-student, mother of two young children and running a farm would have been much more difficult without you making everyday life a bit easier. Thanks to the cottage for housing me –a great part of this thesis was written there. 3 Erik, thank you for your love and support, and for taking care of our children, home and the farm when I spent most of my time writing. Anton Mattias and Ingrid Elise, my dearest treasures, thank you for your endless love and for being constant reminders of what really matters in life <3 Ås, January 2016 Ragnhild Aabøe Inglingstad 4 Summary Inglingstad, R. A. 2016. Quality of Norwegian goat milk for cheese production. Norwegian University of Life Sciences, Philosophiae Doctor Thesis, 2016:19, ISSN: 1894-6402, ISBN: 978-82-575-1348-1 Norwegian goat milk has faced a number of challenges related to the quality of the milk. These challenges have been particularly related to poor rennet coagulation properties and off- flavours. The aim of the project "Quality