Emissions of volatile organic compounds (VOCs) from the food and drink industries of the European community

Atmospheric Environment Vol. 27A, No. 16, pp. 2555-2566, 1993.

Pergamon Press Ltd.

Printed in Great Britain.

E M I S S I O N S O F V O L A T I L E O R G A N I C C O M P O U N D S (VOCs) FROM THE FOOD AND DRINK INDUSTRIES OF THE EUROPEAN COMMUNITY RICHARDSON, RICHARDP. J. SWANNELL,*N. GInsoNand M. J. WOODFIELD Warren Spring Laboratory, Gunnels Wood Road, Stevenage, Herts, SG1 2BX, U.K.

NEILR. PASSANT, STEPHENJ.

and JAN PIETER VAN DER LUGT, JOHAN H. WOLSINK a n d PAUL G. M. HESSELINK TNO, P.O. Box 6011, 2600 JA Delft, The Netherlands (First received 4 October 1992 and in final form 22 July 1993) Abstract--Estimates were made of the amounts of volatile organic compounds (VOCs) released into the atmosphere as a result of the industrial manufacture and processing of food and drink in the European Community. The estimates were based on a review of literature sources, industrial and government contacts and recent measurements. Data were found on seven food manufacturing sectors (baking, vegetable oil extraction, solid fat processing, animal rendering, fish meal processing, coffee production and sugar beet processing) and three drink manufacturing sectors (brewing, spirit production and wine making). The principle of a data quality label is advocated to illustrate the authors' confidence in the data, and to highlight areas for further research. Emissions of ethanol from bread baking and spirit maturation were found to be the principle sources. However, significant losses of hexane and large quantities of an ill-defined mixture of partially oxidized hydrocarbons were noted principally from seed oil extraction and the drying of plant material, respectively. This latter mixture included low molecular weight aldehydes, carboxylic acids, ketones, amines and esters. However, the precise composition of many emissions were found to be poorly understood. The total emission from the food and drink industry in the EC was calculated as 260 kt yr- 1. However, many processes within the target industry were found to be completely uncharaeterized and therefore not included in the overall estimate (e.g. soft drink manufacture, production of animal food, flavourings, vinegar, tea, crisps and other fried snacks). Moreover, the use of data quality labels illustrated the fact that many of our estimates were based on limited data. Hence, further emissions monitoring is recommended from identified sources (e.g. processing of sugar beet, solid fat and fish meal) and from uncharacterized sources. Key word index: Air pollutants, gaseous industrial emissions, data quality, emission factors, ethanol, hexane.

ABBREVIATIONSAND UNITS

INTRODUCTION

CSO, Central Statistical Office (U.K.) DoE, Department of the Environment (U.K.) DPMVO, Dutch Produktschap voor Margarine Vetten en Olien EC, European Community MAFF, U.K. Ministry of Agriculture, Fisheries and Food MHPPE, Ministry of Housing, Physical Planning and Environment (Netherlands) OECD, Organization of Economic Cooperation and Development UNECE, United Nations Economic Commission for Europe US, EPA United States Environmental Protection Agency VOC, volatile organic compound kt, kilotonne (1000 tonnes) Mt, megatonne (1,000,000 tonnes) hi, hectolitres (100 #).

There is increasing public concern over emissions of volatile organic compounds (VOCs) from industrial processes and the air pollution problems they cause. The most significant problem is likely to be the production of photochemical oxidants, e.g. ozone and peroxyacetyl nitrate (Bouscaren et al., 1987; Derwent and Jenkin, 1991; Japer et al., 1991), although VOCs may also contribute to global warming (Fishman, 1991; Derwent, 1990). Photochemical oxidants are toxic to humans, damage crops and are implicated in the formation of acid rain (Swedish Environmental Protection Agency, 1991; Fishman, 1991). Emissions of VOCs also contribute to the localized pollution problems of toxicity and odour (Bouscaren et al., 1987). The transboundary nature of photochemical oxidant pollution has stimulated international cooperation and, as a consequence, member states of the

*To whom correspondence should be addressed. © 1993 Crown Copyright.

2555

2556

N.R. PASSANTet al.

European Community (EC) are in the process of developing V O C reduction programmes. These programmes require inventories of emissions from industrial processes giving data on mass emissions and the compounds present. Emissions of V O C s from the food and drink industries in the EC are thought to be significant, but to date these emissions have been poorly characterized; researchers in the past have tended to concentrate purely on the odour nuisance. In fact, for many sectors of the target industries, an estimate of the mass emission of V O C s has not been made before. It is, therefore, important to review our current understanding and examine the quality of the data. The data quality indicator is fundamental to the interpretation of the emission estimates (United States Environmental Protection Agency [US EPA'I, 1988). It establishes the confidence with which each estimate in the inventory should be treated and prioritizes future work. Data were compiled on seven food manufacturing sectors (baking, vegetable oil extraction, solid fat processing, animal rendering, fish meal processing, coffee production and sugar beet processing) and three drink manufacturing sectors (brewing, spirit production and wine making).

METHODOLOGY In this work, a broad definition of VOCs is used, namely: "VOCs are all organic compounds of anthropogenic nature, other than methane, that are capable of producing photochemical oxidants by reactions with nitrogen oxides in the presence of sunlight" (United Nations Economic Commission for Europe, 1991). Typical VOCs from the food and drink industry are likely to include organic solvents, odorous emissions of partially oxidized hydrocarbons from the heat treatment of foods and the organic by-products of fermentation. Emission estimates have been compiled by comparing published figures from different sources or combining available process emission factors and production statistics. Emission factors relate the mass emission of a VOC to some readily available process parameter (Eggleston and Mclnnes, 1987; Marlowe, 1992). For example, the loss of ethanol from bread baking may be quoted as 3.3 kg t- 1 of production. Emission factors may also be quoted in relation to raw materials used or even per capita. The product of the emission factor and a relevant process statistic gives an estimate of the overall mass emission of VOCs. Breaking the emission estimate down this way enables emission factors from one country to be applied to others if relevant production statistics are available. However, this extrapolation is only advisable if there is little difference in the method of production between the countries. In this paper each source of VOC emission within an industrial activity was identified rather than simply providing an overall emission factor for the sector. This has rarely been attempted in the past. For example, brewing has been divided into barley malting wort boiling, fermentation and the drying of spent grain to produce animal feeds. Emission factors have been derived for as many of these sources as possible so that the significance of each source within the industry can be determined. The VOC emission estimates quoted in this report are obtained from various literature sources, industrial contacts

and measurements. The U.K. estimates are based on work carried out at the Warren Spring Laboratory for the U.K. Department of the Environment (Gilham et al., 1992; Marlowe, 1992). These estimates are incorporated into the official U.K. Inventory which is published in the U.K. Department of the Environment's annual Digest of Environmental Protection and Water Statistics (Department of the Environment [DOE], 1991). The estimates are continually updated as new information is acquired. Emission estimates for the Netherlands are included in the Dutch plan for VOC emission control, KWS 2000 (Ministry of Housing, Physical Planning and Environment, Netherlands [MHPPE], 1989). Emission estimates for other European countries have been given by the Organisation for Economic Co-operation and Development (OECD; 1990) and by CORINAIR (an organization formed by the Commission of the European Communities, DG-XI [Veldt, 1991]). The United Nations Economic Commission for Europe (UN ECE) has also compiled VOC emission estimates (Rentz et al., 1990). In order to indicate the data quality and hence the confidence that can be attached to the data, the US EPA method of assigning letters to each estimate has been broadly adopted (US EPA, 1988). The definitions have been refined slightly for clarity and these are given below. The US EPA guidelines consist of 5 categories "A"-"E". We have modified the definitions to combine the A and B categories. The US EPA (1988) defined an "A" category as a "data set based on a composite of several tests using analytical techniques such as GC/MS and Can be considered representative of the total population". For "B" the US EPA (1988) suggest the same definition except that the "composite of several tests.., can be considered representative of a laroe percentage of the total population" (our italics). We feel that it is important to carry out measurements at industrial sites which are fully representative of the sector. For example, let us speculate that there are three different types of baking processes used in the EC, although one type is used predominantly. A large percentage of the total population could be monitored by just studying plants using the most popular process, thus warranting a "B" in the US EPA definition. However, if valuable resources are to be spent on a monitoring programme, the authors feel that they should be targeted so as to be fully representative of the whole industry, that is by analysing emissions from each process used in the EC. Industry statistics on which process is most widely used can then be used to provide an overall emission estimate for the sector. Therefore, to reflect this assertion the US EPA (1988) definitions for "A" and "B" have laden combined into a single "B" category (see below), and as such no "A" category has been defined. Data Quality Definitions B--Estimate based on many measurements made at a large number of sites considered entirely representative of the source sector. C--Estimate based on a number of measurements at a small number of representative sites, or an engineering calculation based on a number of relevant facts. D---Estimate based on a single measurement or an engineering calculation derived from a number of relevant facts and assumptions. E--Estimate based on an engineering calculation derived only from assumptions.

RESULTS Baking

Bread is leavened by yeast and is baked using one of two processes; the straight-dough process and the sponge-dough process. In the former, the ingredients

VOC emissions from food and drink industries are mixed, fermented and baked. In the latter, only part of the ingredients are initially mixed and allowed to ferment, with the remainder added to the mix and fermented just prior to baking (US EPA, 1985). In Europe the straight-dough process prevails. The bulk of dark rye bread, biscuit production and all cake manufacture involves the use of chemical leavening agents (Kulp and Hepburn, 1978). The major component in VOC emissions from bread baking is thought to be ethanol produced by the fermentation reaction (American Institute of Baking, 1987), although few measurements of VOC emissions have been made. There is an odour associated with the emission so other compounds are likely to be present which have not yet been identified (Rentz et al., 1990). Therefore, the data quality for the estimate of the components in the emission was D. The Centre Interprofessionnel Technique d'Etudes de la Pollution Atmospheriqu~ (Paris, France) use an emission estimate for bread baking of 6 kgt-1 of product (Rentz et al., 1990), the U.K. inventory uses 5 kgt -1 (Munday, 1990); the data quality for these emission factors are not known. Nieman (1982) suggests 2.8 kgt-~ for wholemeal bread and 3.8 kgt-1 product for other baking processes. The relative amounts of other baking and wholemeal bread manufacture for the EC are unknown, therefore a simple average of the two emission factors is suggested giving an overall factor of 3.3 kgt-1. The production of bread in the EC in 1990 was 23.6 Mt (Netherlands Bakery Association, 1990) giving a total VOC emission of 79 kt with a data quality of D. The use of VOC abatement technology in the EC baking industry and its effectiveness remain to be determined.

Production of veoetable oils Vegetable oil production involves the cleaning and crushing of oil seeds, solvent extraction of the oils and treatment of the waste to produce seedcake for animal feed (Finelt, 1979). Hexane is the only solvent used for seed oil extraction that has been identified (Rentz et al., 1990; personal communication with the Ministry of Agriculture, Fisheries and Food [MAFF], 1991), although experimentation has been carried out with other organic and inorganic solvents. Therefore, hexane is suggested as the major species emitted; the data quality is D. The seedcake produced after extraction is generally dried before it is sold for animal feed. By comparison with the drying of spent grain noted in the brewing industry (US EPA, 1985) the emission from oil-bearing seeds may well contain a mixture of carboxylic acids and aldehydes (US EPA, 1985). The data quality is E. For solvent loss, Finelt (1979) suggested 19kg VOCs t - i of seed; the official U.K. inventory gives a figure of 6 kg t- 1 (Munday, 1990) and data from the Netherlands offers 0.85 kgt-1 (Swannell et al., 1991).

2557

The reasons for these differences are thought to be due to the general improvement in recent years in plant conditions, increasing solvent recovery and leading to greater emission control. Data are available on the mass of raw material processed in a number of EC Member States in 1990 (Dutch Produktschap voor Margarine Vetten en Olien [DPMVO], 1990), but no data are available on the condition of the plants and the extent of emission control. Data from the Dutch industry suggest that controls have improved considerably over the last decade (Swannell et al., 1991). It has been assumed that this improvement has occurred throughout the EC and the emission estimate was calculated using an emission factor of 0.85 kg t- 1. Vegetable oil production uses 22Mtyr -1 of seed in the EC in 1990 (DPMVO, 1990) suggesting a hexane emission of at least 20 kt with a data quality of D. The emission factor for .the drying of grain is 1.31 kgt -1 (US EPA, 1985), thus the drying of seed residue after oil extraction it is assumed will produce similar amounts of VOCs. In the EC, assuming all the processed seed are dried (i.e. 22 Mt), the overall emission would be 29 kt yr-1. It is not known if this emission is controlled to any extent and the data quality is therefore E.

Production of solid fat and margarine Solid animal fat is stripped from fresh meat and carcasses, heat treated and deodorized to form lard. Margarine comes from the hydrogenation of vegetable oils. Both these processes can result in the emission of VOCs (Applewhite, 1978). No data are available on the chemical composition of the gaseous effluent arising from animal fat production. However, Applewhite (1978) notes that the deodorizing process used in fat processing is intended to remove lower molecular weight hydrocarbons, aldehydes, ketones and carboxylic acids. The compounds arising from margarine manufacture are not known. As such, the species emitted from animal fat production are thought to be a mixture of aldehydes, ketones and carboxylic acids with a data quality of E. The species emitted from margarine manufacture need to be determined. The authors have been unable to find information to derive emission factors for solid fat and margarine production. However, this area is a high priority for further investigation since the EC production in 1990 was estimated to be approximately 3-4 Mt of solid fat alone (Central Statistical Office U.K. [CSO], 1991). Animal rendering Animal rendering is the processing of animal carcasses, blood, skin and feathers to produce animal feeds, glue, fertilizers and similar products. Processing techniques involve heat treatment followed by separation of fat (tallow) and solids (greaves). Most plants are fitted with some odour abatement (Bailey and Viney, 1979).

2558

N.R. PASSAWret al.

Animal rendering emissions are known to contain a was 742 kt in 1988 (CSO, 1991). The weight of fish wide range of compounds and the precise composition matter processed by U.K. fishmeal plants in 1990 was depends on the type of feedstock and its condition 250 kt and this has remained constant for the last five (Bailey and Viney, 1979). In a typical sample of stack years (MAFF, personal communication). This is equiemission from an animal rendering plant, researchers valent to 33.7% of landed fish. Weights of landed fish have found hydrocarbons, alcohols, aldehydes, car- throughout the EC can be found in a standard referboxylic acids, esters, amines, amides, sulphides and ence book (Hunter, 1992), giving a total weight of thiols and trace quantities of ketones, indoles, thio- 3231 kt (most, but not all the data referred to 1988, phenes and pyridenes (Miller, 1974; Bailey and Viney, and Denmark's catch was excluded). It is assumed that 1979; Langenhove et al., 1982). A detailed list of the a similar percentage of fish and shellfish was processed components in rendering exhausts is given elsewhere at fishmeal plants in all EC states. This suggests that (Swanneil et al., 1991). The major components are 1089 kt of fish was processed in the EC in fishmeal aldehydes, carboxylic acids, sulphides, and thiols and factories. The authors can only find one VOC emission factor the data quality is C. Bailey and Viney (1979) found concentrations in the for fish processing and this is for trimethylamine region of 100 ppm and a mass concentration of ap- production from fish cookers (Faith, 1977), which may proximately 500 m g m -3. More recent work in the not be as significant a source of VOCs as fish dryers U.K. (Swannell et al., 1991) suggests that efficient (Bailey and Viney, 1979). This report suggested that biological scrubbers can reduce emissions by more 0.15 kg trimethylamine is produced per tonne of fresh than 90%. Typical overall exhaust flows can vary fish processed and 1.75 kg t - ~ is produced from stale from 500 m 3 t- ~ for rendering cookers to 2700 m 3 t- 1 fish (Faith, 1977). Assuming that mostly fresh fish are for blood dryers (Miller, 1974). Taking the average processed, this suggests 0.16 kt yr-~ are emitted from exhaust flow of 1600m3t -t, an emission factor the EC. However, it is not clear whether this statistic of 0.8 kg t- ~ of feedstock for uncontrolled plant is refers to a factory with or without emission control. Also, it gives no indication of the total amount of suggested. In the U.K., 1.8 Mt of inedible animal is rendered VOCs produced during fish cooking. As a result, no each year (MAFF, personal communication), equival- suggestion of emission factors from fish processing ent to 30 kg per capita. Applying this to the rest of the have been made. However, given the size of EC suggests that 10 Mt of inedible animal matter is the production statistic this area requires further rendered, giving a total emission of 8 kt yr- t. How- investigation. ever, because of the highly odorous nature of the emission much of the industry is likely to be con- Coffee processing trolled. The authors suggest an arbitrary figure of 2/3 Two sources of VOC emissions have been identifor the proportion of plants controlled with an effici- fied; the roasting of green coffee and the use of organic ency of 90%. Thus, an emission of 3.2 ktyr -~ is solvents to decaffeinate coffee. Roasting of green coffee suggested, with a data quality of E. beans is carried out in plants throughout the EC. After the roasting, the coffee beans are cooled by air in order Fish processing The fish meal industry processes fish and fish offal to condense the aroma product on the bean. Both residues into fishmeal (powdered dried fish), animal roasting and cooling may give rise to emissions (Rentz foods and fertilizers. The largest emissions are prob- et al., 1990). Trichloroethene and dichloromethane ably from the fishmeal dryers (Bailey and Viney, 1979) solvents are used by some producers during the decafalthough emissions are also found during cooking, feinating of coffee (Valle-Riestra, 1974; Swannell et al., pressing, screening and centrifuging (Faith, 1977). 1991). Rentz et al. (1990) reported the presence of carAnalysis of gases from the meal dryers of two fishmeal plants (Bailey and Viney, 1979) identified methane- boxylic acids and aldehydes in the exhaust from coffee thiol and trimethylamine as the major components. roasting, in a ratio of 4.5 to 1. Therefore, it is thought The other compounds identified were similar to those that coffee roasting emits carboxylic acids, aldehydes, found in rendering gases. Other workers have noted and coffee decaffeination emits trichloroethene and the presence of acrolein, hydrogen sulphide, ammonia, dichloromethane, The data quality for both is D. Rentz et al. (1990) gives an overall emission factor of butyric acid and pentanoic acid (Faith, 1977). Concen0.6 kg t- ~ of feedstock, for coffee roasting. Emission trations of organic compounds in the exhaust gases factors for the loss of solvent during decaffeination are from a French fishmeal factory have been reported as 226 mg m - 3, with approximately one-quarter of this not known. The net import of green coffee was some being organically combined nitrogen compounds 1.9 Mtyr-~ in 1990 (European Coffee Federation, (Brand and Oliver, 1972). Thus, it is suggested that 1991), giving an overall emission for the EC of emissions from fish processing largely consists of 1.1 kt yr-~, with a data quality of D. partially oxidised hydrocarbons (aldehydes and carboxylic acids), amines, hydrogen sulphide, ammonia Sugar processing and thiols although the data quality is D. The drying of sugar beet residues after the exThe U.K. weight of fish and shellfish landed in 1988 traction of the sugar is a source of VOC emissions.

VOC emissions from food and drink industries Other potential sources of VOCs include the heat treatment of sugar solutions and the crystallization of the final product (Bailey and Viney, 1979). Analyses of dryer emissions from two sugar beet plants were carded out by Bailey and Viney (1979). The emissions were extremely complex with none of the compounds present in concentrations greater than a few parts per million. Compounds identified included, aldehydes, ketones, carboxylic acids, esters and amines. The data quality is D. No emission factors for sugar beet processing have been found. However, as this process involves the drying of plant material it is suggested that the factor should be similar to that found for grain drying (US EPA, 1985). The authors therefore suggest an emission factor of 1.31 kg t-1 of sugar beet processed. In 1988, production of sugar beet in EC countries totals 93.3 Mt of sugar beet (CSO, 1991; Hunter, 1992). Therefore, the emission of VOCs from sugar beet processing is 121 kt in the EC. As with animal rendering the emission is highly odorous and likely to be controlled. The authors arbitrarily suggest 2/3 of plants are controlled with an efficiency of 90%. The overall emission estimate is therefore 48 kt with a data quality of E. Beer

Beer production will produce VOC emissions as a result of curing (malting) the grain, mixing and heating (mashing) of raw materials to produce wort, drying of the spent grain (in some EC countries) and fermentation and storage of the beer. The principle emission sources are likely to be from the roasting of grain, the boiling of wort and the drying of the spent grain (Buckee et al., 1982). The authors suggest that the emissions from the curing of the barley may be similar to that of coffee roasting (i.e. aldehydes and carboxylic acids) because both processes involve the roasting of seeds. The compounds emitted from wort boiling consist of aldehydes, esters and dimethyisulphide (Buckee et al., 1982). Fermentation evolves ethanol primarily and grain drying is thought to produce primarily aldehydes and carboxylic acids (US EPA, 1985). For wort boiling and grain drying the data quality for the identified species is D; for the other processes it is E. For the malting of grain, the authors suggest the same emission factor (0.6 kgt-1) that was used for coffee roasting. However, this is likely to be an overestimate of the real value, as coffee roasting is a more vigorous process. None the less, at present accurate values for malting are not available. Approximately 900 kt of carbohydrate (which is assumed to be provided by 100% barley malt) is required to produce 6030 kt of beer (U.K. Brewers Society, personal communication). EC beer production for 1988 (World Drink Trends, 1992) amounted to 26 Mt. On this basis the authors suggest that 3.9 Mt of barley malt was produced for beer, giving an overall emission of 2.3 kt VOCsyr- 1 with a data quality of E.

2559

During wort boiling, a total organic carbon emission of 1.36 gh1-1 of wort has been measured (Muller, 1990). Assuming the species present average 50% carbon, this factor equates to a mass emission of 2.72 g hi- 1. Recent work carded at the Warren Spring Laboratory suggests the emission factor may be between 0.52 and 7.08 g carbon hi -1 (Gibson et al., 1993). A median point in this range (3.8 g carbon hi- 1) may provide a reasonable estimate. If the volume of final product (26 Mt) is assumed to be equivalent to the volume of wort then an emission estimate of 1.0 kt can be derived with a data quality of C. Some breweries do condense wort boiling vapours so the emission may be lower than this. The emission from fermentation has been estimated by the industry as being 0.2% of yield (U.K. Brewers Society, personal communication). More recently, measurements conducted at a pilot and industrial scale suggest a more accurate estimate is 0.05 g carbon/g ethanol (Gibson et al., 1993). Beer production is 26 Mt which contains an average alcohol concentration of approximately 5% w/w (Gibson et al., 1993) giving an ethanol yield of 1.3 Mt. The emission is therefore 0.65 Kt with a data quality of C. Many breweries do however collect fermentation gases to produce a saleable carbon dioxide product which may further reduce the emissions. The US EPA have reported an emission factor of 1.31 kgt -1 for the drying of spent grain (US EPA, 1985). The authors have suggested that 3.9 Mt of barley malt is used for beer manufacture (see above). The extent of grain drying in the EC is not known, most it is thought is delivered wet as animal feed. For example, in the U.K. no grain by-products from brewing are thought to be dried (Brewing Research Federation, personal communication). Hence if 30% of this grain is dried in EC countries, this will result in 1.5 kt VOCs from this process. However, the weight of malted grain remaining after beer manufacture is unknown, the extent of grain drying and emission control within the EC are also unknown, therefore the data quality for this estimate is E. Spirits

Spirits are produced by distillation of a fermented product. Fermented grain (e.g wheat, maize, and barIcy in the case of whisky) and malt are used for the production of whisky, gin and vodka, while wine or fruit juices are distilled to produce brandy (Packowski, 1978). Distillation is usually carried out in closed vessels; losses to atmosphere are therefore minimal (Packowski, 1978). Emissions of VOCs are thought to be primarily a result of maturation (US EPA, 1985), although malting, cooking and mashing of the grain, fermentation and the drying of residues are all thought to produce VOCs. As a result the emission estimates for whisky and brandy, which are known to have a considerable maturation period (Packowski, 1978), have been separated from those made for other spirit manufacture.

2560

N.R. P^ss^wr et al.

As mentioned in the previous section, the authors suggest that the malting of grain is likely to lead to the emission of compounds similar to that found in coffee roasting (i.e. carboxylic acids and aldehydes). The data quality for these emissions is E. In spirit manufacture, hops are not used and therefore there is no wort boiling. The starch in the grain is converted to maltose by a mashing process (Packowski, 1978). Mashing consists of two phases, cooking (i.e. gelatinization of starch) and conversion, which decomposes the starch to maltose. At one grain distillery, the grain is cooked at 144°C and 2.1 x 105 Pa for 30 rain. It is then cooled, and in whisky manufacture, it is mixed with green malt and mashed at approximately 60°C for 30 min. The liquid and solid residue is then cooled to 22°C and pumped into the fermenters (N. Passant, unpublished report, 1991). Packowski (1978) notes that there are three different methods of cooking the grain for spirit production: (1) a batch process at 100°C for 30 min; (2) a batch process conducted under pressure at 120-152°C (as recorded by Passant, 1991); (3) a continuous process conducted in a pressure cooker at 170-177°C for 2-6 min. It is not known which of these processes predominates in EC countries. Moreover, the VOC emissions from the grain cooking and mashing are not known. However, the authors suggest that the compounds emitted from the cooking and mashing processes may be similar to those arising from wort boiling during beer manufacture (e.g. aldehydes, esters and dimethyl sulphide). The data quality is E. Analysis by gas chromatography of the emission from four fermentation units in a U.S. whisky distillery reported an ethanol concentration of 99.56% with the remaining compounds being higher alcohols and esters (US EPA, 1988). The data quality is C. The distillation of the fermented product is a potential source of VOC emissions; however, the efficiency of distillate recovery is high and therefore the losses are thought to be low (Packowski, 1978). Emissions are likely to be mainly ethanol, however, impurities with lower boiling points than ethanol could also be present. Data quality is D. The authors have been unable to derive any emission factors for this source. The distilled spirit is diluted with water and transferred to wooden casks. The U.K. Customs and Excise is thought to allow for a loss of up to 0.1% of the spirit during casking; however, this has not been officially confirmed. The emission is expected to be predominantly ethanol but no measurements have been made. The data quality is E. The drying of grains used for spirit manufacture is thought to be a very similar process to that used in brewing. Therefore, the emission will be a complex mixture of aldehydes and carboxylic acids (US EPA, 1985). The data quality is E. During maturation of spirits, ethanol is emitted and in the U.K. the loss is recorded for taxation purposes

(N. Passant, unpublished report, 1991). The data quality is D. No data on emission estimates for the cooking and mashing processes have been found. Malted grain is primarily used in whisky manufacture, largely for the production of malt whisky (which makes up 45% of total whisky production [Scotch Whisky Association, 1991]). The total amount of malt used annually is not known, but it is likely to be much smaller than the amount used to make beer. Owing to the paucity of data no estimate has been made for malting. In terms of the alcohol lost in fermentation an emission factor of 0.05 % of the yield has been suggested for brewing which uses a similar process (see Beer above). Total ethanol production in the EC was 925 kt in 1990 (World Drink Trends, 1992) suggesting an emission of 0.5 kt yr-1 with a data quality of E. An estimate of the amount of VOC emissions produced from grain drying can be derived from information obtained from the Scotch Whisky Association (Scotch Whisky Association, personal communication). For the production of malt whisky, 1 t of malt produces 395 ~ (312 kg) of ethanol. However, for grain whisky 1 t of grain and malt yields 370 E (292 kg) of ethanol. In the U.K. in 1990, whisky contributed 85 % of total U.K. spirit production (U.K. Customs and Excise, personal communication; World Drink Trends, 1991), that is 346kt. Malt whisky constituted 45% of the total amount of whisky produced (Scotch Whisky Association, 1991). The remainder will probably consist largely of gin and vodka. Brandy production is thought to be 227 kt yr= 1 (assumed to be 80% of the production from France, Spain, and Portugal and 10% of Germany [World Drink Trends, 1992]) and does not require grain. The remaining spirit production in the EC probably uses grain as its source of carbohydrate. Therefore, the amount of grain required to manufacture the non-brandy ethanol (698 kt) in the EC can be calculated as 2.4 Mt grain yr = 1. Assuming the emission factor for grain drying from spirit manufacture is the same as that for beer (1.31 kg t- 1; US EPA, 1985), and assuming that all of the grain used in the EC is dried (although this is by no means certain), the total VOC emission is approximated as 3.1 kt yr- 1. However, the degree of VOC abatement from grain drying in the EC remains to be determined. Such information would substantially improve confidence in this estimate to which a data quality of E must be assigned. Packowski (1978) reported that over a 12-year period the ethanol losses during maturation of whisky in the US averaged 3% yr-1. However, the Scotch Whisky Association suggest that the average annual ethanol loss during whisky maturation is 2%yr -1 based on measurements of the weight of unmatured whisky and final product (Scotch Whisky Association, personal communication). This is in agreement with the loss assumed by the U.K. Customs and Exoise Department for the calculation of duty (hi. Passant, unpublished Report, 1991). Typical grain whiskies

VOC emissions from food and drink industries may be matured for 3-6 yrs, malt whiskies are matured for 8-20 yrs (N. Passant, unpublished report, 1991). Brandy is matured for between 3 and 8 years (Packowski, 1978). Vodka is not matured; however, gin can be (Packowski, 1978), although the authors are unsure as to how long. Therefore, emissions from the storage of brandy and whisky are only considered. The authors suggest a total ethanol loss of 12% corresponding to an average of 6 yrs maturation for whisky and 8% for brandy (based on an average of 4 yrs maturation). EC spirit production is approximately 925 kt ethanol yr-1 (World Drink Trends, 1992) of which 352ktyr -1 is thought to be whisky (85% of U.K. production and 100% of the production from Eire) and 227 Mt yr- 1 is thought to be brandy (assumed to be 80% of the production from France, Spain, and Portugal and 10% of Germany [World Drink Trends, 1992"1). Theremaining 346 kt is made up of vodka, gin, etc. This would suggest that the total ethanol loss due to spirit maturation is approximately 42.2 kt yr- ~ for whisky and 18.2 ktyr-1 from brandy. The total emission is therefore 60.4 kt yr- ~ with a data quality of C for whisky and E for other spirits. Wine

Wine is produced by the fermentation of grape juice. Wine making is a major industry in southern EC

2561

Member States and in Germany. VOC emissions can arise from losses during fermentation of the must and during wine decanting (Rentz et al. 1990). In France, the losses during decanting are estimated to be only 3% of fermentation emissions. During fermentation the escaping gas entrains VOCs consisting of 98% ethanol with the remainder primarily other alcohols and aldehydes (US EPA, 1985). The data quality for the identified species was D.

Table 1. Potential sources of VOC's from the food industry as yet uncharacterized Uncharacterized food processes Dried milk production Condensed milk production Fish cooking and smoking Meat cooking and smoking Crisp production and other fried snacks Roasting of peanuts and cashew nuts, etc. Flavour extraction (e.g. hops) Flavourings production Vinegar production Soft drink manufacture Tea production and herbal infusions Drying of fruit and vegetables (for soups, etc.) Animal food production Industrial peeling of vegetables

Table 2. A summary of the species thought to be emitted from food and drink industries Process Baking Vegetable oil extraction Extraction Cake drying Solid fat processing Animal rendering Fish meal processing Coffee processing Roasting Decaffeination Sugar beet drying Brewing Malting of barley Wort boiling Fermentation Grain drying Spirit production Malting Grain cooking and mashing Fermentation Distillation Casking Grain drying Storage Wine making

Major components of emissions

Data quality

Ethanol

D

Hexane Carboxylic acids Aldehydes Aldehydes, ketones, carboxylic acids Aldehydes, carboxylic acids, sulphides, thiols Aldehydes, carboxylic acids, amines, hydrogen sulphide, ammonia, thiols

D E E C D

Aldehydes, carboxylic acids Dichloromethane, trichloroethene Aldehydes, amines, carboxylic acids, esters, ketonos

D D D

Aldehydes, carboxylic acids Aldehydes, esters, dimethylsulphide Ethanol Aldehydes, carboxylic acids

E D E D

Aldehydes, carboxylic acids Aldehydes, esters, dimethylsulphide Ethanol Ethanol Ethanol Aldehydes, carboxylic acids Ethanol Ethanol

E E C E E E C D

2562

N.R. PAss~ocret al.

Veldt (1991) calculated an average emission factor for white and red wine of 0.34 g kg-1 and 0.81 g k g - ! , respectively. The factors reported in a US EPA survey (US EPA, 1985) are lower but this may reflect differences in the production procedure. The wine production by EC in 1988 was 16 Mt of which 6.1 Mt was produced by Germany (World Drink Trends, 1990). Assuming that Germany produces predominantly white wine and the other countries produce approximately equal volumes of red and white an emission factor of 10 kt y r - 1 is obtained with a data quality of D. Other foods Some other food processes, listed in Table 1, are potential sources of VOC emissions. However, the

authors have been unable to find information on species emitted or the size of emissions. Summary A summary of the species identified from food and drink manufacture from each process is summarized in Table 2. The emission factors that have been derived are shown in Table 3 and the best emission estimates with the appropriate data quality estimation are summarized in Table 4. The species produced from food and drink manufacture can be split into three major components, ethanol, hexane and a mixture of partially oxidized hydrocarbons (Tables 2 and 4). The total emission from the food and drink industry is estimated as 260 kt VOCs yr-1.

Table 3. A summary of emission factors for sectors within the food and drink industries Industrial process

Emission factor

Baking

3.30 kg t - x bread

Vegetable oil extraction Solvent extraction . Seed drying

0.85 kg t - 1 oil 1.31 kgt -1 seed

Solid fat processing

ID

Animal rendering (Uncontrolled) (Controlled)

0.80 kg t - 1 feedstock 0.08 kg t- ~ feedstock

Fish meal processing (Fresh fish) (Stale fish)

0.15 kg trimethylamine t - 1 fish 1:75 kg trimethylamine t- ~ fish

Coffee production Roasting Decaffeination

0.60 kg t- 1 green coffee ID

Sugar beet processing (Uncontrolled) (Controlled) Brewing Malting Wort boiling Fermentation Grain drying Spirit production Malting Grain cooking and mashing Fermentation Distillation Casking Grain drying Maturation Whisky Brandy Wine making White wine Red wine ID = insufficient data.

1.31 kgt -1 sugar beet 0.13 kgt -~ sugar beet 0.60 kg t- 1 barley 3.8 g hi- ~ wort 0.05 kg t- ~ alcohol yield 1.31 kgt -~ grain ID ID 0.05 kg t- ~ alcohol yield ID ID 1.31 kgt -~ grain 120 kgt- ~ alcohol 80 kg t- ~ alcohol 0.34 kg t- 1 wine 0.81 kgt -1 wine

VOC emissions from food and drink industries

2563

Table 4. A summary of the emission estimates from sectors within the food and drink industries

Industrial process

~mission estimate Octyr- 1)

Data quality

Baking Vegetable oil extraction Solvent extraction Grain drying Solid fat processing

79

D

20 29 ID

D E

Animal rendering Fish meal processing

3 ID

E

Coffee production Roasting Decaffeination

1 ID

D

Sugar beet processing

48

E

Brewing Malting Wort boiling Fermentation Grain drying Spirit production Malting Grain cooking and mashing Fermentation Distillation Casking Grain drying Maturation Whisky Brandy Wine making Total ethanol Total partially oxidized hydrocarbons Total hexane TOTAL VOC ESTIMATE

2

E

1 1 2

C C E

ID ID 1 ID ID 3

E

42 18 10

C E D

E

151 89 20 260

ID-- insufficient data. All emission estimates are quoted to the nearest kilotonne (kt).

CONCLUSIONS The main compounds emitted by food and drink manufacturers are thought to be ethanol, hexane and a mixture of partially oxidized hydrocarbons (for example: carboxylic acids, aldehydes, ketones, alcohols, and esters). Only a few emissions consisted of single compounds, most consisted of many components. Our estimate of the size of the emission (260 kt) suggests that the food and drink industry contributes significantly to air pollution in the EC. To put this in perspective, the most recent set of total VOC emission estimates from stationary sources in the EC (except Greece and Belgium, who did not provide estimates) suggest 7.9 Mt were emitted in 1985 (EC, 1992). Thus, the food and drink industry constitutes approximately 3% of the total. However, it is not clear whether each country included all industries in

their estimates and no indication of data quality is available. Generally, the compounds identified react with oxides of nitrogen in the presence of sunlight leading to the formation of photochemical oxidants. These oxidants are toxic to humans, damage crops and are implicated in the formation of acid rain (Swedish Environmental Protection Agency, 1991; Fishman, 1991). Different VOCs are thought to have different potentials for forming photochemical oxidants (Derwent and Jenkin, 1991; Japer et al., 1991). In general the species emitted from the target industries (low molecular weight alkanes, alcohols, carboxylic acids, ketones, and aldehydes) have been assigned a medium potential for oxidant formation by some workers (Derwent and Jenkin, 1991). VOCs also contribute to global warming either as greenhouse gases themselves or as precursors to greenhouses gases

2564

N.R. PASSANTet al.

such as ozone and carbon dioxide (Fishman, 1991; Derwent, 1990). Many emissions from the food industry are also extremely odorous. Chlorinated compounds are not thought to contribute significantly to photochemical oxidant formation (Derwent and Jenkin, 1991), but they can be toxic to humans as well as contributing to the greenhouse effect (Pearce, 1989; Derwent, 1990). Only coffee decaffeination was identified as using chlorinated solvents in this work (Valle-Riestra, 1974). But further research may find they are used in some of the uncharacterized industries, for example flavourings manufacture or vegetable peeling. Overall, the data quality for our estimates were poor because few reliable analytical measurements have been made. Most of data warranted either a D or an E. In only six cases were the data considered worthy of data quality assessment of C; animal rendering (species), spirit fermentation and storage (species), weft boiling and fermentation for beer manufacture and whisky maturation (emission estimate). Although our estimates suggest that food and drink manufacture may be significant sources of VOCs in the EC, substantial further work has to be carried out before these emissions estimates can be relied upon with any great certainty. Moreover, there are a number of sectors of the target industry which remain completely uncharacterized. For example, no data on the emissions from solid fat processing, fish processing or the industries recorded in Table 1 were available. The reasons for the poor data qualities assigned to many estimates are two-fold. Firstly, emission factors derived from one industrial process are used for other processes which use similar practices. Secondly, in some cases arbitrary assumptions are used because actual data are not known or are confidential. These problems are difficult to overcome and require careful co-ordination of effort between institutes and universities which are compiling air pollution estimates. Moreover, the regular publication of analyses of gaseous emissions in the academic literature should be further encouraged. Difficulties are encountered not only because gaseous emissions are poorly characterised but also because the detailed knowledge of the industries themselves is difficult to obtain. For example, what proportion of distilleries in Europe dry grain for cattle feed, how many use some form of abatement technology and how effective is it? These types of data are difficult to find but would certainly help in compiling accurate estimates. Hence, to compile good estimates of VOC emissions, three types of information are required: 1. Detailed analytical data of stack emissions in relation to a production statistic for each process used in the industry; 2. Accurate EC-wide production statistics; and 3. Careful study of the industry to note differences in production methods and the degree of VOC abatement.

The data quality assessments are a useful tool for targeting additional effort to areas which are particularly poorly understood. In the first instance, it is more important to improve the quality of estimates from D's and E's to C's and B's, particularly for industries which are thought to produce large amounts of VOCs such as baking, vegetable oil extraction and sugar beet processing. Secondly, additional monitoring must be carried out to quantify the emissions from the uncbaracterised sources. These data should be published in academic journals so that they are readily accessible and verifiable. Too much useful information resides in inaccessible reports and confidential documents. Our data does have important implications for the types of abatement technology that could be used to reduce or eliminate these sources of air pollution. Most (if not all) the identified species are biodegradable (Passant et al. 1992) under the right conditions. Potentially therefore, biological methods (such as biofilters, bioscrubbers and trickling bed filters) may be a cost-effective method of controlling these emissions (Passant et al., 1992; Diks and Ottengraf, 1991) and are currently in use at some factories particularly in northern Europe. In conclusion, it seems that the food and drinks industries produce substantial emissions of VOCs in the EC every year and that these emissions contribute to the formation of photocbemical oxidants and hence air pollution. However, our emission estimates are generally based on little data and further monitoring is definitely required in virtually all sectors. Some sectors are as yet completely uncharacterized. Further information on the industrial processes used in the EC and the efficacy of the abatement technology in use would be most valuable. Our use of data quality assessments has helped to target emissions which are particularly poorly understood and guide further research and monitoring to these areas. We recommend that data quality estimates should be included in any inventory of VOC emissions and that the publication of measurements of VOC emissions in the open scientific literature should be encouraged. Acknowledgements--This work was funded by the European Community as part of the Science and Technology in the Environment Programme (STEP) and by the U.K. Department of the Environment. The EC project is entitled "Abatement of large intractable organic emission sources by the use of biological processes" (STEP project No. 900431).

REFERENCES

American Institute of Baking (1987) How much ethanol are your ovens emitting? Milling and Baking News, edition dated 17 February 1987. Applewhite K. (1987) Fat and fatty oils. In Encyclopedia of Chemical Technolooy, 3rd edition (edited by Mark H. F., Othmer D. F., Overberger C. G. and Scaborg G. T.), volume 9, pp. 795-831. John Wiley and Son, New York. Bailey J. C. and Viney N. J. (1979) Analysis of odours by gas

VOC emissions from food and drink industries chromatography and allied techniques. Warren Spring Laboratory Report No. LR 298 (AP), Stevenage, Herts, U.K. Bouscaren R., Veldt C. and Frank R. (1987) Hydrocarbons-identification of air quality problems in member states of the European Communities. Commission of European Communities, Report No. EUR 10646. Published by the Commission of the European Communities, DirectorateGeneral, Telecommunications, Information Industries and Innovation, Batiment Jean Monnet, Luxembourg. Brand H. D. and Oliver F. (1972) Odour control through catalytic combustion. Fishing News Int., October issue, pp. 44-45. Brewers Society (1990) Beer Facts. Pamphlet published by The Brewers Society (U.K.), 42 Portman Square, London, W1H 0BB. Buckee G. K., Malcom P. T. and Peppard T. L. (1982) Evolution of volatile compounds during wort boiling. J. Inst. Brew. 88, 175-181. Central Statistical Office (1991) Annual Abstract of Statistics No. 127 (edited by Dennis G.). Her Majesty's Stationary Office (HMSO), London. Department of the Environment U.K. (1991) Digest of Environmental Protection and Water Statistics, No. 14. HMSO, London. Derwent R. G. (1990) Trace gases and their Relative Contribution to the Greenhouse Effect. Report AERE-RI3716. HMSO, London. Derwent R. G. and Jenkin M. E. (1991) Hydrocarbons and the long range transport of ozone and PAN across Europe. Atmospheric Environment 25A, 1661-1678. Diks R. M. and Ottengraf S. P. (1991) Process engineering aspects of biological waste gas purification. In Proceedings of a Symposium on Environmental Biotechnology (edited by Verachtert H. and Verstraete W.), pp. 353-368. Royal Flemish Society of Engineers, Belgium. Dutch Produktschap voor Margarine Vetten en Olien (DPMVO) (1990) Annual Report, PO Box 3095, Rijswijk, NL 2280GB, Holland. EC (1992) Environment Statistics 1991. Published by the statistical office of the European Community (Eurostat). L-2920 Luxembourg, Eggleston H. S. and Mackinnis G. (1987) Methods for the compilation of air pollutant inventories. Report No. LR634 (AP) Warren Spring Laboratory, Stevenage, Herts, U.K. European Coffee Federation (1991) European Coffee Report 1990. European Coffee Federation, P.O. Box 90445, NL 1006 BK, Amsterdam, The Netherlands. Faith W. L. (1977) Agriculture and agriculture-products processing. In Air Pollution Volume I V (edited by Stern A. C.), 3rd edition, pp. 655-684. Academic Press, New York. Finelt S. (1979) Air pollution abatement facilities at soybean processing plants. J. Air Pollut. Control Ass. 29, 1192-1196. Fishman J. (1991) The global consequences of increasing tropospheric ozone concentrations. Chemosphere 22, 685-695. Gibson N., Marlowe I. T., Swannell R. P. J. and Woodfield M. (1993) VOC emissions from the Brewing Industries (manuscript in preparation.) Gilham C., Leech P. and Eggleston S. (1992) U.K. emissions of air pollutants 1970-1990. Warren Spring Laboratory, Stevenage, Herts, U.K. Report LR 887 (AP). Hunter B. (1992) The Stateman's Yearbook 1992-1993, 129th edition. Macmillan, London. Japer S. M., Wallington T. J., Rudy S. J. and Chang T. Y. (1991) Ozone-forming potential of a series of oxygenated organic compounds. Envir. Sci. Technol. 25, 415-420. Kulp K. and Hepburn F. N. (1978) Bakery processes (yeastraised products). In Encyclopedia of Chemical Technology, 3rd edition (edited by Mark H. F., Othmer D. F., Overberger C. G. and Seaborg G. T.), volume 3, pp. 438-449. John Wiley and Son, New York.

2565

Langenhove H. R. van, Van Wassenhove F. A., Coppin L K., Van Acker M. R. and Schamp N. M. (1982) Gas chromatography mass spectrometry identification of organic volatiles contributing to rendering odours. Envir. Sci. Technol. 16, 883-886. ,Marlowe I. T. (Ed.) (1992). Emissions of VOCs in the UK: a review of emission factors by species and processes. Report No. LR882 (PA). Warren Spring Laboratory, Stevenage, Hefts, U.K. Miller T. L. (1974) Controlling rendering plant odours. In Proceedings for Control Technology for Agricultural Air Pollutants Speciality Conference, Memphis, Tennessee, 18-19 March, pp. 81-103. Air Pollution Control Association, Pittsburgh, U.S.A. Ministry of Housing, Physical Planning and Environment (1989). Control Strategy for Emissions of Volatile Organic Compounds--Project KWS 2000. Published by the Dutch Ministry of Housing, Physical Planning and Environment, PO Box 20951, 2500 EZ The Hague, Netherlands. Report No. VROM 00202/4-90. Muller K. (1990) Removing odorous gases from brewhouse vapours. Brewing Distilling Int., June 1990, 20-22. Munday P. K. (1990) U.K. emissions of air pollutants 1970-1988. Warren Spring Laboratory, Stevenage, Hefts, U.K. Report LR 764 (AP). Netherlands Bakery Association (1990) Annual Report 1990. Bedrijfschap voor bet Bakkersbedrijf, Eisenhowerlaan 124, 2517 KM, Den Hague, Netherlands. Nieman W. (1982) Air and water emissions from bakeries, part 1; air emissions during baking of bread and rusk. Published by TNO (IGMB), Netherlands, Report No. 82-944. Organization for Economic Cooperation and Development (1990). Control Strategies for Photochemical Oxidants across Europe. OECD, 2 rue Andre-Pascal, 75775 Paris CEDEX 16, France. Packowski G. E. (1978) Beverage spirits, distilled. In Encyclopedia of Chemical Technology, 3rd edition (edited by Mark H. F., Othmer D. F., Overberger C. G. and Seaborg G. T.), volume 3, pp. 830-863. John Wiley and Son, New York. Passant N. R. (1991) Visit to a grain and a malt distillery. Unpublished WSL report, September 1991. Passant N. R., Richardson S. J., Swannell R. P. J., Woodfield M. J., van der Lugt J. P., Wolsink J. H., Hesselink P. G. M., Hecht V., Brebbermann D. and Bischoff H. (1992) Biodegradability of the volatile organic compound (VOC)s emissions from the food, drink and metal degreasing industries. In Biotechniques for Air Pollution Abatement and Odour Policies (edited by Dragt A. J. and Van Ham J.), MECC Congress Proceedings, pp. 315-325. Elsevier, Amsterdam. Pearce F. (1989) Methane: the hidden greenhouse gas. New Sci., 6 May, 37-41. Rentz O., Jourdan M., Roll C. and Schneider C. (1990). Emissions of Volatile Organic Compounds (VOCs) from Stationary Sources and Possibilities for their Control. Published by the Institute of Industrial Production, University of Karlsruhr, Germany, Report No. OBA 91-010. Scotch Whisky Association (1991) Statistical Report 1991. Published by the Scotch Whisky Association, 20 Atholl Crescent, Edinburgh, EH3 8HF, U.K. Swannell R. P. J., Richardson S. J., Passant N. R., Woodfield M. J., van der Lugt J. P., Wolsink J. H., Hesselink P. G. M., Hecht V., Brebbermann D. and Bischoff H. (1991) Biodegradability and Emissions of Volatile Organic Carbon Compounds from the Food, Drink and Metal Degreasing Industries. Published by TNO Environmental and Energy Research, P.O. Box 6011, Delft, Netherlands for the Commission of the European Communities DG XII. Report No. R91/381. Swedish Environmental Protection Agency (1991) Strategy for volatile organic compounds. Stockholm, Sweden. United Nations Economic Commission for Europe (1991) Protocol to the 1979 Convention on Long-range

2566

N. It. PASSAWret al.

Transboundary Air Pollution Concerning the Control of Emissions of Volatile Organic Compounds or their Transboundary Fluxes, p. 3. Published by the United Nations. Report No. ECE/EB.AIR/30. United States Environmental Protection Agency (1985) Compilation of air pollutant emission factors. Volume 1. Stationary point and area sources. 4th edition, EPA Report AP-42. North Carolina, U.S.A. United States Environmental Protection Agency (1988) Air emissions species manual. Volume 1. Volatile organic compound species profiles. U.S. EPA, Report EPA-450/2-

88-003a. North Carolina, U.S.A. Valle-Reistra J. F. (1974) Food processing with chlorinated solvents. Food Technoi., Felmmry, 25-32. Veldt C. (1991) Development of EMEP and CORINAIR emission factors and species profiles for emissions of organic compounds. TNO report No. 91-229, TNO, P.O. Box 6011, Delft, Netherlands. World Drink Trends (1990) NTC Publications Ltd, Henley on Thames, Oxon, U.K.