(ISO 6632 nternational Standard INTERNATIONAL ORGANIZATION FOR STANDARDIZATION MEXAYHAPOAHAR OPrAHW3AuNA nO CTAHAAPTW3AuWWORGANISATION INTE RNATIONALE DE NORMALISATION Fruits, vegetables and derived products - Determination of volatile acidity Fruits, legumes et produits derivés - Détermination de I'acidité volatile First edition - 1981-11-01 UDC 634/635 : 548.813 Ref. No. ISO 6632-1981 (E) 0 6632-1981 (E) Descriptors : agricultural products, fruit and vegetable products, tests, determination, volatility, acidity. Copyright International Organization for Standardization Price based on 9 pages Not for Resale Foreword Iso (the International Organization for Standardization) is a worldwide federation of national standards institutes (Iso member bodies). The work of developing Inter- national Standards is carried out through ISO technical committees. Every member body interested in a subject for which a technical committee has been set up has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with Iso, also take part in the work. Draft International Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as International Standards by the iso Council. International Standard iSO 6632 was developed by Technical Committee ISO/TC 34, Agricultural food products, and was circulated to the member bodies in May 1980. It has been approved by the member bodies of the following countries : Australia Ireland Portugal Austria Israel Romania Brazil Kenya South Africa, Rep. of Canada Korea, Dem. P. Rep. of Spain Malaysia Czechoslovakia Thailand USSR Egypt, Arab Rep. of Netherlands France New Zealand Venezuela Germany, F. R. Peru Yugoslavia Hungary Philippines India Poland The member body of the following country expressed disapproval of the document on technical grounds : USA @ International Organization for Standardization, 1981 Printed in Switzerland Copyright International Organization for Standardization from IHS Not for Resale INTERNATIONAL STANDARD ISO 6632-1981 (E) Fruits, vegetables and derived products - Determination of volatile acidity Scope and field of application 4.2 Phenolphthalein, 10 g/l solution in 95 % (V/V) 1 ethanol. This International Standard specifies a method for the deter- mination of volatile acidity in fruits, vegetables and derived 4.3 Tartaric acid, crystallized. products. 4.4 Lime water, diluted 1 + 4. The method is applicable to all fresh products and to pro- ducts preserved without chemical preservatives, as well as to Dilute one volume of the saturated calcium hydroxide solution products to which sulphur dioxide has been added with or (4.5) with four volumes of water. Allow the mixture to stand without one of the following preservatives : sorbic acid, ben- until calcium carbonate is precipitated and decant the limpid zoic acid, formic acid. solution which shall be alkaline to the phenolphthalein sol- ution (4.2). Definition 2 This solution is intended for use in the steam generator (5.2.1) 2.1 volatile acidity : All lower molecular weight fatty acids. 4.5 Calcium hydroxide, limpid saturated solution. such as acetic acid and propionic acid, in free or combined form, with the exception of formic acid. The volatile acidity, determined by the method specified in this Apparatus International Standard, is expressed either in milliequivalents per 100 ml or per 100 g of product, or in grams of acetic acid Usual laboratory apparatus, and in particular : per 100 ml or per 100 g of product. 5.1 Mechanical mill Principle 5.2 Apparatus for extrainment by steam distillation (see Acidification of a test portion with tartaric acid, entrainment of the figure), comprising the following elements : the volatile acids by steam distillation, and titration of the distillate with standard volumetric sodium hydroxide solution in 5.2.1 Steam generator, suitable for the production of steam the prese nce