Re‐evaluation of agar (E 406) as a food additive
2016; Wiley; Volume: 14; Issue: 12 Linguagem: Inglês
10.2903/j.efsa.2016.4645
ISSN1831-4732
AutoresAlicja Mortensen, Fernando Aguilar, Riccardo Crebelli, Alessandro Di Domenico, María José Frutos Fernández, Pierre Galtier, David Michael Gott, Ursula Gundert‐Remy, Claude Lambré, Jean‐Charles Leblanc, Oliver Lindtner, Peter Moldéus, Pasquale Mosesso, Agneta Oskarsson, D. Parent‐Massin, Ivan Stanković, Ine Waalkens‐Berendsen, Rudolf Antonius Woutersen, Matthew Wright, Maged Younes, Leon Brimer, Paul Peters, Jacqueline Wiesner, Anna Christodoulidou, Federica Lodi, Alexandra Tard, Birgit Dusemund,
Tópico(s)Consumer Attitudes and Food Labeling
ResumoEFSA JournalVolume 14, Issue 12 e04645 Scientific OpinionOpen Access Re-evaluation of agar (E 406) as a food additive EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS), EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS)Search for more papers by this authorAlicja Mortensen, Alicja MortensenSearch for more papers by this authorFernando Aguilar, Fernando AguilarSearch for more papers by this authorRiccardo Crebelli, Riccardo CrebelliSearch for more papers by this authorAlessandro Di Domenico, Alessandro Di DomenicoSearch for more papers by this authorMaria Jose Frutos, Maria Jose FrutosSearch for more papers by this authorPierre Galtier, Pierre GaltierSearch for more papers by this authorDavid Gott, David GottSearch for more papers by this authorUrsula Gundert-Remy, Ursula Gundert-RemySearch for more papers by this authorClaude Lambré, Claude LambréSearch for more papers by this authorJean-Charles Leblanc, Jean-Charles LeblancSearch for more papers by this authorOliver Lindtner, Oliver LindtnerSearch for more papers by this authorPeter Moldeus, Peter MoldeusSearch for more papers by this authorPasquale Mosesso, Pasquale MosessoSearch for more papers by this authorAgneta Oskarsson, Agneta OskarssonSearch for more papers by this authorDominique Parent-Massin, Dominique Parent-MassinSearch for more papers by this authorIvan Stankovic, Ivan StankovicSearch for more papers by this authorIne Waalkens-Berendsen, Ine Waalkens-BerendsenSearch for more papers by this authorRudolf Antonius Woutersen, Rudolf Antonius WoutersenSearch for more papers by this authorMatthew Wright, Matthew WrightSearch for more papers by this authorMaged Younes, Maged YounesSearch for more papers by this authorLeon Brimer, Leon BrimerSearch for more papers by this authorPaul Peters, Paul PetersSearch for more papers by this authorJacqueline Wiesner, Jacqueline WiesnerSearch for more papers by this authorAnna Christodoulidou, Anna ChristodoulidouSearch for more papers by this authorFederica Lodi, Federica LodiSearch for more papers by this authorAlexandra Tard, Alexandra TardSearch for more papers by this authorBirgit Dusemund, Birgit DusemundSearch for more papers by this author EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS), EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS)Search for more papers by this authorAlicja Mortensen, Alicja MortensenSearch for more papers by this authorFernando Aguilar, Fernando AguilarSearch for more papers by this authorRiccardo Crebelli, Riccardo CrebelliSearch for more papers by this authorAlessandro Di Domenico, Alessandro Di DomenicoSearch for more papers by this authorMaria Jose Frutos, Maria Jose FrutosSearch for more papers by this authorPierre Galtier, Pierre GaltierSearch for more papers by this authorDavid Gott, David GottSearch for more papers by this authorUrsula Gundert-Remy, Ursula Gundert-RemySearch for more papers by this authorClaude Lambré, Claude LambréSearch for more papers by this authorJean-Charles Leblanc, Jean-Charles LeblancSearch for more papers by this authorOliver Lindtner, Oliver LindtnerSearch for more papers by this authorPeter Moldeus, Peter MoldeusSearch for more papers by this authorPasquale Mosesso, Pasquale MosessoSearch for more papers by this authorAgneta Oskarsson, Agneta OskarssonSearch for more papers by this authorDominique Parent-Massin, Dominique Parent-MassinSearch for more papers by this authorIvan Stankovic, Ivan StankovicSearch for more papers by this authorIne Waalkens-Berendsen, Ine Waalkens-BerendsenSearch for more papers by this authorRudolf Antonius Woutersen, Rudolf Antonius WoutersenSearch for more papers by this authorMatthew Wright, Matthew WrightSearch for more papers by this authorMaged Younes, Maged YounesSearch for more papers by this authorLeon Brimer, Leon BrimerSearch for more papers by this authorPaul Peters, Paul PetersSearch for more papers by this authorJacqueline Wiesner, Jacqueline WiesnerSearch for more papers by this authorAnna Christodoulidou, Anna ChristodoulidouSearch for more papers by this authorFederica Lodi, Federica LodiSearch for more papers by this authorAlexandra Tard, Alexandra TardSearch for more papers by this authorBirgit Dusemund, Birgit DusemundSearch for more papers by this author First published: 21 December 2016 https://doi.org/10.2903/j.efsa.2016.4645Citations: 14 Correspondence: fip@efsa.europa.eu Requestor: European Commission Question number: EFSA-Q-2011-00507 Panel members: Fernando Aguilar, Riccardo Crebelli, Alessandro Di Domenico, Birgit Dusemund, Maria Jose Frutos, Pierre Galtier, David Gott, Ursula Gundert-Remy, Claude Lambré, Jean-Charles Leblanc, Oliver Lindtner, Peter Moldeus, Alicja Mortensen, Pasquale Mosesso, Agneta Oskarsson, Dominique Parent-Massin, Ivan Stankovic, Ine Waalkens-Berendsen, Rudolf Antonius Woutersen, Matthew Wright and Maged Younes. Acknowledgements: The Panel wishes to thank the following for the support provided to this scientific opinion: Dario Battacchi and Lemmetyinen Juho. The ANS Panel wishes to acknowledge all the European competent institutions, the Member State bodies and other organisations that provided data for this scientific opinion. Adopted: 7 November 2016 AboutSectionsPDF ToolsExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Abstract The EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS) provides a scientific opinion re-evaluating the safety of agar (E 406) as a food additive. In the European Union (EU), agar (E 406) has been evaluated by the Scientific Committee for Food (SCF) in 1989, who allocated to agar a not specified acceptable daily intake (ADI), and by the Joint FAO/WHO Expert Committee on Food Additives (JECFA) in 1974, who considered very few data to conclude to a not limited ADI. According to the conceptual framework for the risk assessment of certain food additives re-evaluated under Commission Regulation (EU) No 257/2010, the Panel considered that the safety assessment is limited to the use and use levels received from industry in 7 food categories for which data were considered in this opinion out of the 70 food categories in which agar (E 406) is authorised; an indicative high refined exposure assessment up to 26 mg/kg body weight (bw) per day has been calculated in toddlers at the 95th percentile (non-brand-loyal scenario); agar is unlikely to be absorbed unchanged and slightly fermented by intestinal microbiota; sufficient toxicity data were available; there was no concern with respect to the genotoxicity of agar; no carcinogenic effects were reported in carcinogenicity studies in mice and rats at the doses of 4,500 mg/kg bw per day and 2,500 mg/kg bw per day, respectively, the highest doses tested; oral intake of agar (4,500 mg/person corresponding to 64 mg/kg bw per day) was tolerated in humans for 12 weeks without noticeable side effects. Therefore, the Panel concluded that there is no need for a numerical ADI for agar and that there is no safety concern for the general population at the refined exposure assessment for the reported uses of agar as a food additive. Summary Following a request from the European Commission, the Panel on Food Additives and Nutrient Sources added to Food (ANS) was asked to re-evaluate the safety of agar (E 406) when used as a food additive. The Panel was not provided with a newly submitted dossier and based its evaluation on previous evaluations and reviews, additional literature that has come available since then and the data available following a public call for data. The Panel noted that not all original studies on which previous evaluations were based were available for re-evaluation by the Panel. Agar (E 406) is authorised as a food additive in the European Union (EU) in accordance with Annex II to Regulation (EC) No 1333/2008 on food additives. Specific purity criteria on agar (E 406) have been defined in Commission Regulation (EU) No 231/2012. In the EU, agar (E 406) has been evaluated by the Scientific Committee for Food (SCF) in 1989 (SCF, 1989) and by the Joint FAO/WHO Expert Committee on Food Additives (JECFA) in 1974 (JECFA, 1974). The SCF did not consider it necessary to specify an acceptable daily intake (ADI), and consequently, allocated to agar a not specified ADI. JECFA considered very few data (two animal studies, one human study) to conclude to a not limited ADI. Agar is extracted from certain strains of marine algae of the families Gelidiaceae and Gracilariaceae and relevant red algae of the class Rhodophyceae (Commission Regulation (EU) No 231/2012). Agar (E 406) is defined as a hydrophilic colloidal polysaccharide consisting mainly of galactose units with a regular alternation of l- and d-isomeric forms. These hexoses are alternately linked with alpha-1,3 and beta-1,4 bonds in the copolymer. On about every tenth d-galactopyranose unit, one of the hydroxyl groups is esterified with sulfuric acid which is neutralised by calcium, magnesium, potassium or sodium. Because of its polysaccharidic nature, agar can be a substrate of microbiological contamination during storage. The latter has been recently demonstrated by the mycotoxin contaminations of gums (Zhang et al., 2014). The Panel noted that the differences in the microbiological criteria for agar between the specifications given by the EU Regulation and those given by JECFA are not decisive. Degradation of agar has been investigated in an in vitro human model. This study demonstrated that agar would be partially fermented during its passage through the large intestine by the action of the intestinal tract microflora. The rate of hydrolysis in the gastrointestinal tract in humans is unknown; however, the Panel considered that agar is unlikely to be absorbed unchanged, and that the limited extent of fermentation of agar would lead to products such as short-chain fatty acids (SCFA). Based on the available knowledge on the role of SCFA as end products of the fermentation of dietary fibres by the anaerobic intestinal microflora (Topping and Clifton, 2001; Den Besten et al., 2013), the Panel considered that their potential formation as fermentation products from agar does not raise any concern. The acute toxicity of agar in mice, rats and rabbits is low. No adverse effects have been identified up to 10,000 mg/kg body weight (bw) per day in mice and 4,500 mg/kg bw per day in rat, the highest dose tested, in two dose range-finding subchronic toxicity studies performed by the National Toxicology Program (NTP) in 1982 (Doc. provided to EFSA n.8). No genotoxic activity was observed in the available in vitro and in vivo genotoxicity assays with agar. The Panel noted that the package of available studies was limited, but also that agar is routinely used as a substrate in in vitro gene mutation assays in bacteria and mammalian cells. Overall, considering its chemical structure and negligible absorption, the Panel concluded that there is no concern with respect to the genotoxicity of agar (E 406). No chronic toxicity studies according to OECD guidelines have been identified by the Panel. In carcinogenicity studies by NTP (Doc. provided to EFSA n.8, 1982; Melnick et al., 1983), no indication of a substance-related increased tumour incidence was reported. The authors stated that under the experimental conditions used, agar was not carcinogenic to mice and rat at the highest doses tested (up to 4,500 or 2,500 mg/kg bw per day, respectively). The Panel agreed with the authors. No data on reproductive toxicity were available. In the prenatal developmental toxicity studies in rats and hamsters, no maternal and developmental effects were observed up to the highest dose tested (1,140 and 650 mg agar/kg bw per day, respectively) (Doc. provided to EFSA n.3). Agar is used as an adjuvant in the treatment of diabetes and/or obesity (Maeda et al., 2005). This study did not show noticeable side effects in participants receiving a daily dose of 4.5 g agar for 12 weeks agar as an adjuvant in the treatment of diabetes and/or obesity (Maeda et al., 2005). No adverse effects were described for agar as a mild laxative in single doses from 2.75 to 5.5 g or in daily doses from 4 to 16.5 g administered with sufficient fluids, but intestinal stenosis was given as a contraindication (Heber, 2007). Agar (E 406) is authorised in a wide range of foods but reported by industry to be used in a limited number of food categories (9/70). According to the Panel, it is not expected that brand loyalty will result in higher exposure in the general population, except in specific populations consuming foods belonging to the food categories 13.2, 13.3 and 13.4. The Panel therefore selected the non-brand-loyal refined scenario as the most relevant exposure scenario for this additive. In the maximum level and refined scenarios, only seven food categories (out of 70 in which agar is authorised in the Regulation (EC) No 1333/2008) for which data have been reported by industry, were included. The Panel considered that the uncertainties identified would result in an overestimation of exposure for these seven food categories. Considering information from the Mintel Global New Products Database (GNPD), only approximately 50% of the food products labelled with agar (E 406) belonged to food subcategories for which reported use levels were available, and consequently used in the exposure assessment. The Panel noted that given the information from the Mintel GNPD it may be assumed that agar is used in food categories for which no data have been provided by food industry. If this is confirmed, the present assessment would therefore result in an underestimation of the exposure. The Panel further noted that the exposure to agar from its use according the Annex III (Part 1, 2, 3, 4 and 5 section A) to Regulation (EC) No 1333/2008 was not considered in the exposure assessment. The Panel also noted that the refined exposure estimates are based on information provided on the reported level of use of agar (E 406). If actual practice changes, this refined estimates may no longer be representative and should be updated. According to the conceptual framework for the risk assessment of certain food additives re-evaluated under Commission Regulation (EU) No 257/2010 (EFSA ANS Panel, 2014) and given that: the safety assessment carried out by the Panel is limited to the use and use levels in seven food categories for which data were considered in this opinion out of the 70 food categories in which agar (E 406) is authorised; an indicative high refined exposure assessment up to 26 mg/kg bw per day has been calculated in toddlers at the 95th percentile (non-brand-loyal scenario); agar is unlikely to be absorbed unchanged and is slightly fermented by intestinal microbiota; sufficient toxicity data were available; there is no concern with respect to the genotoxicity of agar (E 406); no carcinogenic effects were reported in carcinogenicity studies in mice and rats at the doses of 4,500 mg/kg bw per day and 2,500 mg/kg bw per day, respectively, the highest doses tested; oral intake of agar (4,500 mg/person corresponding to 64 mg/kg bw per day) was tolerated in humans for 12 weeks without noticeable side effects, the Panel concluded that there is no need for a numerical ADI for agar, and that there is no safety concern for the general population at the refined exposure assessment for the reported uses of agar as food additive. The Panel recommended that the maximum limits for the impurities of toxic elements (lead, mercury, cadmium and arsenic) in the EC specification should be revised in order to ensure that agar (E 406) as a food additive will not be a significant source of exposure to those toxic elements in food, in particular for infants and children. The Panel recommended that information on the possible use of formaldehyde should be provided since no such information was made available following the call for data. Due to the discrepancies observed between the data reported from industry and the Mintel database, where agar is labelled in more products than in food categories for which data were reported from industry, the Panel recommended collection of data of usage and use levels of agar (E 406) in order to perform a more realistic exposure assessment. 1 Introduction The present opinion deals with the re-evaluation of the safety of agar (E 406) when used as food additives. Agar (E 406) is an authorised food additive in the European Union (EU) according to Annex II and Annex III of Regulation (EC) No 1333/20081. 1.1 Background and Terms of Reference as provided by the European Commission 1.1.1 Background as provided by the European Commission Regulation (EC) No 1333/2008 of the European Parliament and of the Council on food additives requires that food additives are subject to a safety evaluation by the European Food Safety Authority (EFSA) before they are permitted for use in the EU. In addition, it is foreseen that food additives must be kept under continuous observation and must be re-evaluated by EFSA. For this purpose, a programme for the re-evaluation of food additives that were already permitted in the EU before 20 January 2009 has been set up under the Regulation (EU) No 257/20102. This Regulation also foresees that food additives are re-evaluated whenever necessary in the light of changing conditions of use and new scientific information. For efficiency and practical purposes, the re-evaluation should, as far as possible, be conducted by group of food additives according to the main functional class to which they belong. The order of priorities for the re-evaluation of the currently approved food additives should be set on the basis of the following criteria: the time since the last evaluation of a food additive by the Scientific Committee on Food (SCF) or by EFSA, the availability of new scientific evidence, the extent of use of a food additive in food and the human exposure to the food additive taking also into account the outcome of the Report from the Commission on Dietary Food Additive Intake in the EU3 of 2001. The report 'Food additives in Europe 2000' submitted by the Nordic Council of Ministers to the Commission, provides additional information for the prioritisation of additives for re-evaluation. As colours were among the first additives to be evaluated, these food additives should be re-evaluated with a highest priority. In 2003, the Commission already requested EFSA to start a systematic re-evaluation of authorised food additives. However, as a result of adoption of Regulation (EU) 257/2010 the 2003 Terms of References are replaced by those below. 1.1.2 Terms of Reference as provided by the European Commission The Commission asks EFSA to re-evaluate the safety of food additives already permitted in the Union before 2009 and to issue scientific opinions on these additives, taking especially into account the priorities, procedures and deadlines that are enshrined in the Regulation (EU) No 257/2010 of 25 March 2010 setting up a programme for the re-evaluation of approved food additives in accordance with the Regulation (EC) No 1333/2008 of the European Parliament and of the Council on food additives. 1.1.3 Interpretation of the Terms of Reference This re-evaluation refers exclusively to the uses of agar (E 406) as a food additive in food, including food supplements, and does not include a safety assessment of other uses of agar as described in Section 3.4.2. 1.2 Information on existing evaluations and authorisations Agar (E 406) is authorised as a food additive in the EU in accordance with Annex II and Annex III to Regulation (EC) No 1333/2008 on food additives. Specific purity criteria on agar (E 406) have been defined in Commission Regulation (EU) No 231/20124. In the EU, agar (E 406) has been evaluated by the SCF in 1989 (SCF, 1989), who reviewed all the available studies on agar, including acute, subacute, developmental, carcinogenicity and mutagenicity studies. In view of the fact that agar is devoid of toxicity at the highest dose levels tested, the SCF did not consider it necessary to specify an acceptable daily intake (ADI), and consequently allocated to agar a not specified ADI.5 Agar (E 406) was evaluated by the Joint FAO/WHO Expert Committee on Food Additives (JECFA) in 1974 (JECFA, 1974). JECFA considered very few data (two animal studies and one human study) to conclude to a not limited ADI. In 2006, JECFA updated the specifications of agar (JECFA, 2006). Agar (E 406) has also been reviewed by the Nordic Council of Ministers (TemaNord, 2002), who concluded that there is no need for a re-evaluation since the substance is widely used and there is a long history of safe intake of agar as a food. Agar is one of the food additives that composed jelly mini-cups which were suspended in 2004 by the European Commission to be placed on the market and import (Commission Decision 2004/37/EC; EC, 2004), following the measures taken and information provided by the different Member States. Jelly mini-cups are defined as 'jelly confectionery of a firm consistence, contained in semi rigid mini-cups or mini-capsules, intended to be ingested in a single bite by exerting pressure on the mini-cups or mini-capsule to project the confectionery into the mouth'. In 2004, the EFSA Panel on Food Additives, Flavourings, Processing Aids and Materials in Contact with Food (EFSA AFC Panel, 2004) prepared a scientific opinion on a request from the European Commission related to the use of certain food additives derived from seaweed or non-seaweed origin, including agar (E 406) in jelly mini-cups. The AFC Panel concluded that any of these gel-forming additives or of any other type that gave rise to a confectionery product of a similar size, with similar physical and/or physicochemical properties and that could be ingested in the same way as the jelly mini-cups, would give rise to a risk for choking (EC, 2004). The use of these additives in jelly mini-cups is not authorised in the EU.6 Agar is permitted as a binding and viscosity controlling agent in cosmetic products (European Commission database-CosIng7). Agar is included in the EU Register8 of feed additives (Regulation (EC) No 1831/20039). 2 Data and methodologies 2.1 Data The Panel on Food Additives and Nutrient Sources added to Food (ANS) was not provided with a newly submitted dossier. EFSA launched public calls for data,10,11,12 and, if relevant, contacted other scientific risk assessment bodies to collect relevant information from interested parties. The Panel based its assessment on information submitted to EFSA following the public calls for data, information from previous evaluations and additional available literature up to the last Working Group meeting before the adoption of the opinion.13 Attempts were made at retrieving relevant original study reports on which previous evaluations or reviews were based; however, these were not always available to the Panel. The EFSA Comprehensive European Food Consumption Database (Comprehensive Database14) was used to estimate the dietary exposure. The Mintel's Global New Products Database (GNPD) is an online resource listing food products and compulsory ingredient information that should be included in labelling. This database was used to verify the use of agar (E 406) in food products. 2.2 Methodologies This opinion was formulated following the principles described in the EFSA Guidance on transparency with regard to scientific aspects of risk assessment (EFSA Scientific Committee, 2009) and following the relevant existing guidance documents from the EFSA Scientific Committee. The ANS Panel assessed the safety of agar (E 406) as a food additive in line with the principles laid down in Regulation (EU) 257/2010 and in the relevant guidance documents: Guidance on submission for food additive evaluations by the Scientific Committee on Food (SCF, 2001) and taking into consideration the Guidance for submission for food additive evaluations in 2012 (EFSA ANS Panel, 2012). When the test substance was administered in the feed or in the drinking water, but doses were not explicitly reported by the authors as mg/kg body weight (bw) per day based on actual feed or water consumption, the daily intake was calculated by the Panel using the relevant default values as indicated in the EFSA Scientific Committee (2012) for studies in rodents or, in the case of other animal species, by JECFA (2000). In these cases, the daily intake is expressed as 'equivalent to'. When in human studies in adults (aged above 18 years), the dose of the test substance administered was reported in mg/person per day, the dose in mg/kg bw per day was calculated by the Panel using a body weight of 70 kg as default for the adult population as described in the EFSA Scientific Committee Guidance document (EFSA Scientific Committee, 2012). Dietary exposure to agar (E 406) from its use as a food additive was estimated combining food consumption data available within the EFSA Comprehensive European Food Consumption Database with the maximum levels according to Annex II to Regulation (EC) No 1333/200815 and reported use levels submitted to EFSA following calls for data. Different scenarios were used to calculate exposure (see Section 3.3.1). Uncertainties on the exposure assessment were identified and discussed. In the context of this re-evaluation, the Panel followed the conceptual framework for the risk assessment of certain food additives re-evaluated under Commission Regulation (EC) No 257/2010 (EFSA, 2014). 3 Assessment 3.1 Technical data 3.1.1 Identity of the substances According to Commission Regulation (EU) No 231/2012, agar is 'a hydrophilic colloidal polysaccharide consisting mainly of galactose units with a regular alternation of l- and d-isomeric forms. These hexoses are alternately linked with alpha-1,3 and beta-1,4 bonds in the copolymer. On about every tenth d-galactopyranose unit, one of the hydroxyl groups is esterified with sulfuric acid which is neutralised by calcium, magnesium, potassium or sodium. It is extracted from certain strains of marine algae of the families Gelidiaceae and Gracilariaceae and relevant red algae of the class Rhodophyceae.' The Panel noted that not all families and species used in the production of agar are specified in the above definition. According to the reviews by Stanley (2006) and Armisen and Galatas (2000), agar can be extracted not only from species of the families Gracilariaceae, Gelidiaceae, but also from those of Phyllophoraceae and, Ceramiaceae and Ahnfeltiaceae families, all belonging to the red seaweeds (class Rhodophyta) algae. The majority of the raw material is harvested from wild growth (Stanley, 2006), although a commercial cultivation has been reported from Chile (OIiviera and Alveal, 1990). The higher taxonomy of the red algae has long been disputed. Recent systematic systems were published by Saunders and Hammersand (2004), Adl et al. (2005) and Hwan Su Yoon Müller et al. (2006). Since these systems differ from each other and from previous systems in the higher taxa, in the present opinion we therefore only refer to genus and species of such algae. Agar has the CAS Registry Number 9002-18-0, and the EINECS No 232-658-1. Based on structural evaluations, agar is a linear polysaccharide built up of alternating 3-linked β-d-galactopyranose and 4-linked α-l-galactopyranose residues, a substantial part of the α-l-galactose residues may exist as a 3,6-anhydro derivative (Knutsen et al., 1994; Stanley, 2006). Thus, the basic structure of agar consists of a repeating disaccharide unit which is termed 'agarobiose' (Stanley, 2006); the structural formula is presented in Figure 1. Figure 1Open in figure viewerPowerPoint Structural formula of agar linear polysaccharide built up of the repeating disaccharide agarobiose units Older investigations revealed that agar can be separated at least into two polysaccharides named 'agarose' and 'agaropectin' which are both agarobiose polymers (Araki, 1956). Agarose is a neutral gelling fraction and has a high molecular weight above 100,000 Da and a sulfate content usually below 0.15%, while agaropectin is a sulfated non-gelling fraction with a molecular weight of only around 14,000 Da and a sulfate content of 5–8% (Armisen and Galatas, 2000). However, more recent investigations suggest that agar consists not only of two well defined polysaccharides – agarose and agaropectin – but also it is in fact a complex mixture of polysaccharides, ranging from virtually uncharged molecules to various charged galactans, some rich in sulfate, others in pyruvate (Duckworth and Yaphe, 1971; Stanley, 2006; Doc. provided to EFSA n. 2 and 5). Thereby, the structure of agar is highly dependent on the seaweed sources and the manufacturing method (Stanley, 2006). According to Commission Regulation (EU) No 231/2012, agar is odourless or has a slight characteristic odour. Unground agar usually occurs in bundles consisting of thin, membranous, agglutinated strips, or in cut, flaked or granulated forms. It may be light yellowish orange, yellowish grey to pale yellow or colourless. It is tough when damp, brittle when dry. Powdered agar is white to yellowish white or pale yellow. Agar is known under several synonyms such as agar-agar, gelose, Japan agar, Bengal, Ceylon, Chinese or Japanese i
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