OIV COLLECTIVE EXPERTISE DOCUMENT SO2 AND WINE: A REVIEW SO2 AND WINE: A REVIEW 1 MARCH 2021 OIV COLLECTIVE EXPERTISE DOCUMENT SO2 AND WINE: A REVIEW WARNING This document has not been submitted to the step procedure for examining resolutions and cannot in any way be treated as an OIV resolution. Only resolutions adopted by the Member States of the OIV have an official character. This document has been drafted in the framework of Expert Group “Food safety” and revised by other OIV Commissions. This document, drafted and developed on the initiative of the OIV, is a collective expert report. © OIV publications, 1st Edition: March 2021 (Paris, France) ISBN 978-2-85038-022-8 OIV - International Organisation of Vine and Wine 35, rue de Monceau F-75008 Paris - France www.oiv.int 2 MARCH 2021 OIV COLLECTIVE EXPERTISE DOCUMENT SO2 AND WINE: A REVIEW SCOPE The group of experts « Food safety » of the OIV has worked extensively on the safety assessment of different compounds found in vitivinicultural products. This document aims to gather more specific information on SO2. This document has been prepared taking into consideration the information provided during the different sessions of the group of experts “Food safety” and information provided by Member States. Finally, this document, drafted and developed on the initiative of the OIV, is a collective expert report. This review is based on the help of scientific literature and technical works available until date of publishing. COORDINATOR OIV - International Organisation of Vine and Wine AUTHORS Dr. Creina Stockley (AU) Dr. Angelika Paschke-Kratzin (DE) Pr. Pierre-Louis Teissedre (FR) Pr. Patrizia Restani (IT) Dr. Nuria Garcia Tejedor (ES) Ing. Claudia Quini (AR) 3 MARCH 2021 OIV COLLECTIVE EXPERTISE DOCUMENT SO2 AND WINE: A REVIEW SO2 AND WINE FINAL REPORT OF THE EWG Scope 3 Introduction 5 SO2 Technical data 6 Which properties do SO2 or sulfite salts have in wine? 6 SO2 free, SO2 total and SO2 active 6 Authorisation and limits in winemaking 6 Potential adverse reaction to SO2 8 OIV Methods of analysis 11 SO2 levels in wines 12 Conclusions 27 References 28 4 MARCH 2021 OIV COLLECTIVE EXPERTISE DOCUMENT SO2 AND WINE: A REVIEW INTRODUCTION Sulfur dioxide (SO2) and its salts have been added during winemaking since the 17th century. SO2 and its sulfite salts, remain an essential winemaking additive as there is no one other additive that has the same dual properties of anti-oxidation and preservation. It remains a potentially adverse reaction causing and toxic product for wine consumers and winemakers in amounts greater than 10 mg/L, and that accordingly, should be handled with care. Moreover, sulfites are also used as biocide agent in disinfection for sanitation of barrels. This function is not detailed in this report. 5 MARCH 2021 OIV COLLECTIVE EXPERTISE DOCUMENT SO2 AND WINE: A REVIEW The pH value plays an important role on the SO2 SO2 TECHNICAL DATA concentration, with a low pH value in wine, you get a higher percentage of the molecular SO2. If you have Sulfur dioxide (INS 220) has a chemical formula - SO2. less acid, or a high pH value wine, you get a much lower It has a molecular weight of 64.06 g/mol, Chemical percentage of the molecular SO2. Abstracts Service (CAS) Registry Number 7446-09-5 and the European Inventory of Existing Commercial SO2 FREE, SO2 TOTAL chemical Substances (EINECS) number is 231-195-2. Its structural formula is given in Figure 1. AND SO2 ACTIVE When SO2 is incorporated into a must or a wine, a fraction of it will react with sugars, or aldehydes (ethanal) or ketones. The remaining fraction, called free, is the one with the most important properties. SO2 Total = SO2 free + SO2 reacted The most active fraction of free SO2 is called active SO2 Figure 1: Structural formula of SO2 and is composed of molecular SO2. During maturation The most commonly used synonyms for SO2 are and storage, concentrations of free SO2 values of sulfurous acid anhydride and sulfurous oxide. 25 mg/L on red wine and 30 mg /L on white wine are recommended. An active SO2 concentration of WHICH PROPERTIES DO SO2 0.35 mg/L ensures a minimum protection, a value of 0.6 mg/L maximum protection. OR SULFITE SALTS HAVE IN WINE? AUTHORISATION Sulfur dioxide and its salts have two main properties: AND LIMITS IN WINEMAKING Anti-Oxidant If oxygen is present, it will be ‘captured’ by SO2 . A redox Approximately 20-200 mg/L of SO2 may be added reaction to sulfite and further on to sulfate will take during winemaking (Ough 1986) and approximately place. Other molecules such as aroma compounds are 10 - 50 mg/L is formed by the yeast during fermentation, prevented from oxidation. which is usually bound to acetaldehyde on formation. Therefore, when wine is analysed for the concentration Preservative of total SO2, a small amount will always be measured Since the reaction of SO2 with oxygen reduces the regardless of whether sulfur dioxide was added or not oxygen concentration, aerobic microorganisms cannot during the course of winemaking. increase anymore e.g. in wine. Naturally occurring levels of SO2 in wines are usually In winemaking, these properties are important for two around 10 - 20 mg/L. In most wine consuming countries, reasons: wines containing sulfites greater than 10 mg/L must include a statement on the label making the consumer The anti-oxidant effect of SO2 prevents the alteration aware that sulfites are present. of natural aromas of the grapes and wine due to the contact with oxygen. The preservative effect of SO2 helps inhibiting the development of ‘indesirable bacteria’ in the wine as well as sulfur dioxide does when used as disinfectant for sanitation of barrels; this latter function is not discussed further in this report. 6 MARCH 2021 OIV COLLECTIVE EXPERTISE DOCUMENT SO2 AND WINE: A REVIEW Organisation Wine type Limit (mg/L) Legal reference Red < 4g/L 150 White/Rosé < 4g/L 200 OIV OIV Resolution OENO 09/1998 . Red/White/Rosé > 4g/L 300 Sweet/Special wines 400 GSFA Provisions for Food Category 14.2.3 350 mg/kg Codex Alimentarius (Grapes wines) Country Wine type Limit (mg/L) Legal reference Red 130 White 180 Argentina Resolution INV Nº 2/2018 Sweet red 180 Sweet white/Rosé 210 < 35g/L sugars 250 Australia ANZFSC 4.5.1: Clause 5(5)(a) > 35g/L sugars 300 Brazil All 300 ANVISA, Resolution n° 123, 2016 Canada All 350 Canadian Food & Drug Reg. B.02.100 White/Rosé < 5g/L sugars 200 Red < 5g/L sugars 150 White/Rosé ≥ 5g/L sugars 250 Commission Delegated Regulation EU Red ≥ 5g/L sugars 200 (EU) 2019/934 Specific sweet wines 300 Specific sweet wines 350 Specific sweet wines 400 India All 450 Prevention of Food Adulteration Act & Rules, Appendix C, Table 3 Japan All 350 Japan’s Specifications and Standards for Food Additives New < 35g/L sugars 250 Zealand > 35g/L sugars 300 Red < 5g/L 150 White < 5g/L 160 South Liquor Products Act 60 of 1989 Regulations Africa All > 5 g/L 200 Regulation 32 (Table 8) Specific sweet wines 300 USA All 350 27 CFR 4.22(b)(1) 7 MARCH 2021 OIV COLLECTIVE EXPERTISE DOCUMENT SO2 AND WINE: A REVIEW The results of the assessment of the dietary exposure POTENTIAL ADVERSE REACTION to annatto, nitrites, tartaric acid and sulfites within the framework of the second French Total Diet Study TO SO2 (TDS) are reported in Food Additives & Contaminants Journal (Bemrah et al, 2012). The average concentration An adverse reaction from ingestion of SO2 is more (medium bound) in the alcoholic beverages category commonly an intolerance rather than an allergic stood at 46.4 mg/L but wine, taken individually, has adverse reaction. Although the most common symptom a concentration of 92 mg/L. The average dietary is asthma, foods and food additives are not common exposure to sulphites varies from 0.16 mg/kg/day triggers for asthma. Furthermore, adverse reactions (lower bound assumption) to 0.17 mg/kg/day (upper to SO2 in non-asthmatic and non-sensitive individuals bound assumption) in adults and from 0.031 mg/kg/day are rare. Few clinical studies have, however, assessed (lower bound assumption) to 0.04 mg/kg/day (upper the degree to which SO2 additives contribute to wine- bound assumption) in children. In the 95th percentile, induced asthma. The results of these studies have exposure ranges from 0.59 mg/kg/day (LB assumption) been equivocal and hence direct evidence is limited. to 0.60 mg/kg/day (UB assumption) among adults and Furthermore, some individuals report reactions to red from 0.12 mg/kg/ day (LB assumption) to 0.14 mg/kg/ wines only, others to white wines only, some to both day (UB assumption) among children. red and white wines and some to specific brands or types only. Allergists initially believed that 1-3 mg SO2 The major contributors in the adult population are released from wine and inhaled by a sulfite-sensitive similar under both hypotheses (lower and upper bound), individual may trigger an adverse reaction. It has since namely alcoholic drinks (wine, champagne and cider), been clinically demonstrated, however, that SO2 will which represent 77% of total exposure (lower bound) generally only cause an adverse reaction in sulfite- (73% for wine, 2% for champagne and 1% for cider) and sensitive asthmatics, which comprise approximately 74% of total exposure (upper bound (70% for wine, 2% 1.7% of all asthmatics. Steroid-dependent asthmatics are for champagne and 1% for cider), and secondly sugar, most at risk of an adverse reaction.