原文報道：
Scientific Opinion on the safety of glycerol esters of gum rosin for the proposed uses as a food additive
Adopted: 23 June 2010
Published: 14 July 2010
Summary (0.1 Mb)
Opinion (0.2 Mb)
Summary
Following a request from the European Commission to the European Food Safety Authority (EFSA), the Scientific Panel on Food Additives and Nutrient Sources added to Food (ANS) was asked to provide a scientific opinion on the safety of glycerol esters of gum rosin (GEGR) when used as a stabilising and emulsifying food additive in certain non-alcoholic flavoured cloudy drinks and certain cloudy spirit drinks to a maximum level of 100 mg/l.
GEGR have been evaluated by the Joint FAO/WHO Expert Committee on Food Additives (JECFA) in 2009. The Committee established a group ADI of 0 – 25 mg/kg bw/day for GEWR (glycerol esters of wood rosin) and GEGR. The specifications for GEGR were made tentative, pending the submission of additional data and information by the end of 2010 concerning the identity of GEGR, the resin acid composition and methods to identify the individual glycerol esters of rosins and their differentiation. Furthermore, the Committee requested the full reports of the two 90-day toxicity studies in rats performed using oral administration of GEGR, to confirm the validity of the comparison of GEWR with GEGR.
GEGR are obtained by esterification of refined gum rosin originating, according to the petitioner, from Pinus oocarpa Schiede. GEGR are described as a complex mixture of tri- and diglycerol esters of resin acids from gum rosin, with glycerol triabietate as the main component and a residual fraction of monoglycerol esters. Besides the glycerol esters of resin acids [fraction (a)] which amount only to 75.7 - 78.2% of GEGR, 2.8 - 4.2% free resin acids [fraction (b)] and 19 - 20.1% other non-acidic saponifiable and unsaponifiable substances [fraction (c)] are present in GEGR according to the analysis of 3 samples of GEGR, the results of which were provided by the petitioner upon request from the Panel.
The percentages of resin acids derived from fractions (a), (b) and (c) after saponification of GEGR are known. Abietic acid, dehydroabietic acid and communic acid are the main representatives.
The Panel noted, however, that data on the identity and quantity of individual components in fractions (a), (b) and (c) of unsaponified GEGR are missing and also data on the proportions of glycerol monoesters, (1,2)-glycerol diesters, (1,3)-glycerol diesters and glycerol triesters in fraction (a) are not provided.
According to the petitioner, the non-acidic fraction of the source material gum rosin, which is presumed to be at least partly retained during GEGR production and to result in fraction (c), is composed of natural esters of resin acids, esters of fatty acids and of unsaponifiables. As described in published literature, the unsaponifiables in gum rosin comprise more than 40 components, e.g. volatile monoterpenes, diterpene alcohols and diterpene aldehydes, the latter two groups being described as “non volatiles”. The petitioner states that volatile organic compounds of the non-acidic fraction of gum rosin will be stripped off in the manufacturing procedure of GEGR.
The Panel noted that, according to the description of the petitioner, the gum rosin used as source in the production of GEGR meets the definition of the wood rosin as source of GEWR laid down in the Commission Directive 2008/84/EC[1] as far as the content of approximately 10% neutrals in the refined gum rosin is concerned. But the Panel also noted that a high content of fraction (c) in GEGR of up to 20% results after the esterification and final purification. This implies that the percentage of the unknown substances of fraction (c) is twice the percentage of neutrals in the refined source material. According to the petitioner, this increase is due to the new formation of unsaponifiables during the process of esterification at high temperature in the presence of oxygen. The composition of fraction (c) is unknown. The possible occurrence of “non volatile” diterpenic substances (e.g. alcohols, aldehydes, esters) in larger amounts and of 3,5-dimethoxystilbene in fraction (c) has to be taken into consideration. The extent to which compounds of different volatility are removed in the course of manufacturing is unknown.
Physical and chemical parameters in the specification of GEGR are equivalent to those defined by the Commission Directive 2008/84/EC for GEWR limiting e.g. the concentration of free acids in GEGR by the acid value.
The Panel noted that setting limits for glycerol monoesters of resin acids, which are supposed to undergo partial hydrolysis in the gastrointestinal tract, and furthermore information on the levels of fraction (b) and fraction (c) might be relevant for the specifications.
The Panel noted that for GEGR no studies are available on: i) absorption, distribution, metabolism and excretion, ii) short-term and subchronic toxicity (the results of two 90-day toxicity studies in rats fed GEGR were submitted only as short summaries), iii) genotoxicity, iv) chronic toxicity and carcinogenicity, v) reproductive and developmental toxicity.
Considering free resin acids present as fraction (b) in GEGR, selected data on absorption, distribution, metabolism and excretion and on genotoxicity as reviewed in a previous JECFA monograph are available. The Panel noted that there are no data from in vivo genotoxicity testing to overrule positive in vitro findings.
In view of the limited toxicity data available for GEGR, the petitioner submits analytical data to demonstrate that GEGR are chemically equivalent to GEWR (E 445). On this basis, the petitioner claims that the toxicity data for GEWR are directly relevant to GEGR. GEWR have already been authorised by Directive 95/2/EC[2] , allowing their use as a stabiliser and emulsifier in non-alcoholic flavoured cloudy drinks and certain cloudy spirit drinks up to a maximum level of 100 mg/l.
Physical and chemical properties were measured in six lots of GEGR and five samples of GEWR. Infrared (IR) Spectroscopy, Gas Chromatography (GC), and Nuclear Magnetic Resonance (NMR) were used to analyse the products. The results demonstrate that the two products are similar. The percentages of individual resin acids obtained after saponification of GEGR or GEWR are also in the same range. Some difference is observed for the percentages of fraction (c). Taking into account the results of different analyses showing some batch-to-batch variations for GEGR, the values for fraction (c) range from 15.6 to 20.1% for GEGR and 12.5 to 13% for GEWR.
According to the petitioner, currently there are no qualitative and quantitative data available concerning the individual components in fractions (a), (b), and (c) of GEGR and GEWR as a basis for comparison.
The Panel noted that the concentrations of individual resin acids measured in GEWR and GEGR samples after saponification, covering the fraction of free resin acids [fraction (b)], the resin acids derived from glycerol esters [fraction (a)] and the acids derived from esters of fraction (c), are very similar. But apart from the missing qualitative and quantitative analysis of individual glycerol mono- di- and triesters in fraction (a) of GEGR and GEWR, most notably the components of fraction (c) of GEGR and GEWR, which may differ due to different manufacturing procedures and to different botanical sources, are unknown. Since the content of fraction (c) in GEGR accounts for up to 20%, this information is most relevant for the evaluation of the equivalence of GEGR and GEWR.
The Panel could not conclude, based on the chemical data provided, that GEGR and GEWR are chemically equivalent. Therefore, the Panel could not base the safety evaluation of GEGR on the results of the toxicological studies available for GEWR.
Dermal contact sensitisation is seen with different types of rosins and modified rosins and their components, as well as with GEGR and 1-glycerol monoabietate. Since from ingestion of glycerol esters of rosins with beverages, allergic responses have not been reported, the Panel did not consider it likely that the oral exposure via the intended use and use levels of GEGR in beverages is associated with a relevant risk of adverse effects for individuals with a known contact hypersensitivity to rosin or modified rosin products.
The exposure to GEGR was calculated based on the information available from the EFSA Concise Database in Exposure Assessment. The average exposure would range in Europe from 0.07 to 0.74 mg/kg bw/day and at the 97.5th percentile from 0.5 to 3.3 mg/kg bw/day. The Panel also calculated the exposure to GEGR based on the UK data for children using the intake of non-alcoholic flavoured drinks and the intended use level of 100 mg/l. The exposure was estimated to be 1.7 mg/kg bw/day on average and 5.8 mg/kg bw/day at the 97.5th percentile. The Panel noted that these estimates are conservative, since GEGR is not intended to be added to all non-alcoholic flavoured drinks but to citrus-fruit based drinks only.
The Panel concluded that the chemical and toxicological characterisation of GEGR is not adequate and that the absence of toxicological study reports on GEGR prevents the evaluation of the safety of GEGR. The Panel also concluded that there is not sufficient information to evaluate the chemical equivalence of GEGR and GEWR, and that therefore the toxicological data obtained with GEWR could not be used for read across to GEGR.
The Panel concluded that the available data are too limited to conclude on the safety of GEGR as a food additive at the proposed uses and use levels.
