Accepted Manuscript Fermented and ripened fish products in the Northern European countries Torstein Skåra, Lars Axelsson, Gudmundur Stefánsson, Bo Ekstrand, Helge Hagen PII: S2352-6181(15)00005-0 DOI: 10.1016/j.jef.2015.02.004 Reference: JEF 12 To appear in: Journal of Ethnic Foods Received Date: 16 January 2015 Revised Date: 23 January 2015 Accepted Date: 2 February 2015 Please cite this article as: Skåra T, Axelsson L, Stefánsson G, Ekstrand B, Hagen H, Fermented and ripened fish products in the Northern European countries, Journal of Ethnic Foods (2015), doi: 10.1016/ j.jef.2015.02.004. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. ACCEPTED MANUSCRIPT 1 Fermented and ripened fish products in the Northern European countries 2 Torstein Skåra 1* , Lars Axelsson 2, Gudmundur Stefánsson 3, Bo Ekstrand 4 and Helge Hagen 5 3 1 Nofima - Norwegian Institute of Food, Fisheries, and Aquaculture Research, Postboks 8034, 4 NO-4068 Stavanger, Norway 5 2 Nofima - Norwegian Institute of Food, Fisheries, and Aquaculture Research, P.O.Box 210, 6 NO-1431 Ås, Norway 7 3 Matis, Vinlandsleid 12, 113 Reykjavik, Iceland 8 4 Bioconsult AB, Stora Vägen 49, SE-523 61 Gällstad, Sweden 5 MANUSCRIPT 9 Dælivegen 118, NO-2385 Brumunddal, Norway 10 *Author for correspondence: Tel: +47-51844600; Fax: +47-51844651 11 E-mail. [email protected] 12 13 Running title: FermentedACCEPTED fish products in Northern Europe 14 ACCEPTED MANUSCRIPT 15 Abstract 16 In Northern Europe a number of fish products are prepared in such a way that biochemical 17 and microbial action can take place. These are complex processes for which there are few 18 available scientific studies. This article covers the origin, manufacturing, characteristics and 19 consumption of traditional fermented fish products, including surstömming from Sweden, 20 rakfisk from Norway, hákarl from Iceland and the barrel salted herring that was commonly 21 produced in most of Northern Europe. 22 23 Keywords: 24 Fish; Herring; Trout; Fermentation; Salt; Hákarl; SMANUSCRIPTurstömming; Rakfisk 25 26 1. Introduction 27 28 Fish has always ACCEPTEDbeen staple food for people in the Nordic countries but as the fishing was 29 seasonal there was a need to store and preserve fish through the winter months. Drying is the 30 oldest form of food preservation and dried white fish (mainly cod) was historically the most 31 important food commodity in Norway, both as staple food and for trade, especially in the ACCEPTED MANUSCRIPT 32 coastal regions. More fatty fish species, however, e.g. salmon, trout, charr and herring, are not 33 very suitable for drying (Hagen and Vestad, 2012). 34 Use of salt for preservative purposes was known Before Christ in well-developed societies, 35 like China and ancient Egypt (Kurlansky, 2003). The knowledge spread gradually from south 36 to north in Europe; how fast is uncertain, but probably it did not reach the north to any large 37 extent until the Viking Age, along with the extensive trade during this period. Due to long and 38 difficult transportation, salt was expensive and generally scarce, especially in remote inland 39 areas. Instead of using full-salt-preservation (approximately 15-20% w/w), people therefore 40 probably “experimented” using lower salt concentrations when preparing caught fish for 41 storing and found that the procedure sometimes resulted in edible, even tasteful (although 42 smelly!), and lasting products. The techniques varied somewhat with regard to salt 43 concentrations, storage temperatures, storage containers, fish species and handling. In this 44 regard, the cured fish products in mildly salted brineMANUSCRIPT have the same roots, but the different 45 technologies have resulted in quite different processes and products. 46 Fermentation plays an important role in many parts of the world for the production of 47 traditional fish products. In south East Asia, fermented fish products have a long history and 48 they are of great nutritional importance. Fermented fish is an old staple food in European 49 cuisines; for instance, the ancient Greeks and Romans made a famous sauce from fermented 50 fish called garum (Aquerreta et al ., 2002). In Northern Europe, only a few traditional 51 fermented fish productsACCEPTED are still produced. This production relies both on naturally occurring 52 enzymes (in the muscle or the intestinal tract) as well as bacteria. In general, the former is 53 most significant with respect to changing texture as well as producing some of the flavor, and 54 the latter aids the development of aroma and flavor (Beddows, 1985). Unlike the fully 55 fermented Asian products, in Northern Europe some degree of processing – e.g. removal of ACCEPTED MANUSCRIPT 56 gills and some of the intestinal tract is often used and additionally the processing temperature 57 (ambient) is considerably lower. 58 There is also good reason to believe that the general sensory acceptance of aroma and taste 59 was quite different in former times; many people found it hard to accept salt during the 60 Middle Ages. The occurrence of rancid and putrid aroma was a much more natural part of the 61 daily food, which can explain the occurrence of a number of dried and fermented fish 62 products in the Nordic countries. 63 From the 19th century, the modern fishery and fish industry, with industrial preservation, long 64 distance food distribution and the chain of chilling and freezing, with refrigerators and 65 freezers in every home, has totally changed the handling of all food including fish products. 66 The old technologies of drying, fermenting and smoking your fish catches have more or less 67 disappeared, few have survived into the modern supeMANUSCRIPTrmarkets. 68 This article will cover 4 main traditional products: the Icelandic hákarl , the Norwegian 69 rakfisk , the Swedish surströmming and the barrel salted ripened herring, which is quite 70 common in all of Northern Europe. With the exception of hákarl , all the Northern European 71 fermented fish products are salted. 72 Gravlax will not be covered in detail. The word grav-lax , referenced many times in Swedish 73 writing from theACCEPTED middle ages, literally meaning “buried salmon”, probably reflects the use of 74 the relatively low and frost free temperature in the ground (Hagen and Vestad, 2012). At that 75 time gravlax was essentially synonymous with rakfisk , but the meaning has since changed. 76 “Graving ” of fish (or meat) now means a short-time (few days) marination or curing using a 77 salt-sugar-spice mix, giving a much more perishable product than rakfisk . ACCEPTED MANUSCRIPT 78 The canning procedure, introduced in the 19th century, enabled some of these product to be 79 distributed and marketed in shops and stored at home, while traditionally they had been stored 80 in large wooden barrels or smaller, one-liter kegs. The food safety and storage stability of 81 these traditional products can be seen as illustrative of the so-called “hurdle principle”, where 82 not one, but a combination of a number of hurdles for microbial growth, e.g. pH, salt 83 concentration, Lactobacilli , render the final product safe and stable by inhibiting the growth 84 of microbial pathogens and spoilage flora. 85 Common to all these products is the fact that scientific research on the process and products is 86 scarce and available literature is hard to find, especially in the English language. 87 88 MANUSCRIPT ACCEPTED ACCEPTED MANUSCRIPT 89 2. Hákarl 90 91 2.1. Origin 92 Fermenting or curing of hákarl – shark - (Somniosus microcephalus ) has been practiced in 93 Iceland for centuries. Although there was knowledge from neighbouring countries on the 94 common use of salt for preservation, the production of salt was difficult in Iceland as there 95 was shortage of firewood. Other means had to be found and the traditional food preservation 96 methods in Iceland were acidifying using lactic acid (milk whey), fermentation ( kæsing ) and 97 drying. 98 In the Icelandic sagas shark is mentioned, but the referencesMANUSCRIPT are not clear on whether the fish 99 were specifically caught for consumption or had simply drifted ashore (Kristjánsson, 1983). 100 Shark fishing had become common in Iceland during the 14th century and at that time 101 fermented hákarl was an important part of the diet of Icelanders and continued to be so for 102 centuries. 103 Shark liver oil played an important role in the economy of Iceland as an export item and the 104 fermented meat was part of the staple diet; often consumed with other foods such as dried fish 105 (stock fish), breadACCEPTED and rye cakes or simply eaten on its own. The fatty brown meat from the 106 belly flaps ( glerhákarl ) was sliced thinly and used as butter. The cartilage or gristle was also 107 used for food, commonly as hash with some shark flesh, but it needed a lot of fat, mainly 108 tallow. In general all parts of the shark were utilized largely as food, e.g. the eggs and ACCEPTED MANUSCRIPT 109 intestines. The shark skin was commonly used for making shoes but even in tough times the 110 skin was boiled and eaten (Kristjánsson, 1983). 111 Shark fishing reached its peak in the 17th and 18th century, probably due to the strong 112 demand for shark liver oil which was used for lighting lamps in Europe, but fishing continued 113 well into the 20th century (Kristjánsson, 1983).