ISO 1573:1980

Overview

ISO 1573:1980 is an international standard established by the International Organization for Standardization (ISO) that specifies a method for determining the loss in mass of tea when heated at 103 ± 2 degrees Celsius. This measurement is crucial for assessing the moisture content in tea, which affects quality, shelf life, and processing characteristics. The procedure involves drying a test portion of tea in a controlled oven until a constant mass is achieved, ensuring accuracy and reproducibility.

Key Topics

• Scope and Principle
  The standard defines drying tea in air at 103 °C to constant mass to assess loss in mass at 103 °C, which primarily represents moisture content but may include other volatile substances.

• Sample Preparation
  Tea samples must be prepared according to ISO 1839 (Tea - Sampling) for representative and consistent results.

• Test Method

  • Weigh a test portion (~5 g) into a pre-weighed, dried weighing bottle.
  • Dry the sample in an oven at 103 ± 2 °C with the lid removed for 6 hours initially, then in 1-hour increments until mass variation between consecutive weighings is less than 0.005 g.
  • Cool using a desiccator before weighing to avoid moisture gain from air.
  • Repeat the process if mass increases after drying to find the correct constant mass point.

• Calculation and Expression of Results
  Loss in mass is expressed as a percentage of the initial test portion mass using the formula:
  [ \text{Loss in mass (%) } = \frac{m_0 - m_1}{m_0} \times 100 ]
  where ( m_0 ) is initial mass and ( m_1 ) is dried mass.

• Repeatability and Accuracy
  Two separate determinations must be conducted on the same sample. Results must agree within 0.3 g loss per 100 g of sample to be considered repeatable.

• Reporting Requirements
  Test reports should include method details, results, any deviations from the standard procedure, and full sample identification for traceability.

Applications

• Quality Control
  Tea producers and quality inspectors can use ISO 1573:1980 to ensure moisture levels meet regulatory and trading standards, guarding against spoilage and weight discrepancies.

• Product Specification
  Accurate moisture content determination is critical for labeling, compliance, and monitoring tea storage conditions.

• Research and Development
  The method supports studies related to drying processes, shelf-life extension, and optimizing product formulation by providing precise moisture content data.

• Trade and Regulatory Compliance
  Facilitates harmonized moisture testing for international tea trade, promoting fairness and reducing disputes related to product quality.

Related Standards

• ISO 1839: Tea - Sampling
  Defines correct sampling methods to obtain representative tea samples for testing including moisture loss as per ISO 1573.

• International Methods for Moisture Content Analysis
  Other drying and moisture testing standards apply to agricultural products and may complement ISO 1573 in broader quality assessment programs.

• ISO Technical Committees
  Technical Committee ISO/TC 34 oversees agricultural food products and related testing methods, ensuring integrated standardization in food analysis.

Adopting ISO 1573:1980 provides a reliable and internationally recognized procedure for determining moisture-related quality parameters in tea. This ensures product consistency, supports trade standards, and enhances consumer confidence.