ISO 6558-2:1992

Overview

ISO 6558-2:1992 is an international standard developed by the International Organization for Standardization (ISO) that specifies routine methods for determining carotene content in fruits, vegetables, and their derived products. This standard is part 2 of ISO 6558 and focuses specifically on practical, applicable methods for quantifying carotenoids, particularly beta-carotene, in food products.

The standard distinguishes two main analysis methods based on the fat content of the product:

• Method A for products containing 5% fat or less
• Method B for products containing more than 5% fat

This differentiation ensures accurate carotene quantification across a wide range of food matrices.

Key Topics

• Scope of Methods: ISO 6558-2 establishes two distinct routine analytical procedures tailored to products with different fat content levels, facilitating consistent carotene measurements in fruits, vegetables, juices, purees, marmalades, and other derivatives.

• Sample Preparation: Detailed instructions are provided for preparing various types of samples including liquids, viscous, solid, and frozen products to ensure representative and consistent results.

• Extraction Techniques: Carotenes are extracted using mixtures of petroleum ether and acetone or petroleum ether and diethyl ether, depending on the sample type and method. Saponification is applied in Method B to remove fats and other interfering substances.

• Chromatographic Separation: Separation of carotenoids from other substances is achieved by column chromatography using appropriate adsorbents such as alumina or mixed oxides to ensure selective isolation of carotene from other pigments.

• Spectrometric Measurement: Quantification is performed by spectrometric measurement at 450 nm wavelength, a specific absorption peak for carotene, enabling precise determination of content based on absorbance.

• Calculations and Reporting: Formulas and correction factors for calculating carotene concentration in products are standardized, with guidelines for expressing results and reporting analysis details to guarantee reproducibility and traceability.

• Reproducibility and Repeatability: The standard defines repeatability criteria, ensuring that test results are reliable and consistent within a 5% variation when repeated under the same conditions.

Applications

ISO 6558-2:1992 methods are widely applicable in:

• Quality Control in Food Industry: Routine testing of carotene content in raw fruits, vegetables, and processed foods such as juices, purees, and canned products helps monitor nutritional quality and compliance with labeling regulations.

• Nutritional Analysis and Research: Enables laboratories and researchers to accurately assess the carotenoid content, vital for understanding antioxidant levels, vitamin A precursors, and overall product health benefits.

• Regulatory Compliance: Assists manufacturers and food testing labs to meet international standards and legal requirements related to food composition and nutrient claims.

• Product Development: Useful in formulation and fortification studies to verify carotene enrichment and stability in new food products.

Related Standards

• ISO 6558-1: Reference method for carotene content determination in fruits, vegetables, and derivatives.

• ISO 12823: Methods for the determination of carotenoids in foodstuffs using chromatographic and spectrometric techniques.

• ISO 11036: Test methods for carotenoid content in plant materials.

• ISO 29541: Food analysis methods for fat content determination, relevant when applying different carotene analysis methods based on fat level.

Keywords: ISO 6558-2, carotene content determination, fruits vegetables analysis, beta-carotene measurement, routine carotene analysis, food quality control, spectrometric method, carotenoid extraction, column chromatography, food nutrient analysis, fat content food testing.