Overview
ISO 6770:1982 is an international standard published by the International Organization for Standardization (ISO) that specifies precise methods for determining the free-flow and compacted bulk densities of instant tea. Bulk density is a critical parameter affecting instant tea packaging, storage, transportation, and vending machine dispensing, as it defines the relationship between the product’s mass and the volume it occupies. This standard ensures uniform procedures for measuring bulk density with minimized human error, enabling consistent quality control and trade practices worldwide.
Key Topics
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Free-flow bulk density:
This refers to the mass-to-volume ratio of instant tea poured freely (uncompacted) into a measuring container. The method involves pouring a tea sample through a specified funnel into a receptacle of known volume and weighing the contents. The product volume is determined without tapping or vibration, simulating how loose powder behaves under normal conditions.
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Compacted bulk density:
This is the mass-to-volume ratio after the instant tea powder has been compacted through a standardized number of mechanical taps (usually 100) using a jogging volumeter. It reflects the product’s volume after settling and compaction, which has important implications on packaging density and shelf space utilization.
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Sampling and handling:
The standard highlights the importance of careful sample selection from the top, middle, and bottom of the bulk product to ensure representative results. Samples must be stored properly to prevent compression or structural changes that could skew density measurements.
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Apparatus specifications:
Devices used in measurements, such as the funnel, measuring receptacle, balance, and jogging volumeter, are defined with specific dimensions and material requirements to promote reproducibility and comparability. For example, components contacting the sample should be stainless steel to avoid contamination.
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Calculation and reporting:
The standard provides formulas for calculating bulk density expressed in grams per milliliter (g/ml) and stipulates that the average of multiple determinations be used to ensure accuracy. Repeatability criteria require that results from duplicate tests by the same operator agree within 2% of their mean. Test reports must fully document methods, measurements, sampling details, and any anomalies such as lumps in the sample.
Applications
ISO 6770:1982 serves multiple practical purposes within the instant tea industry and associated sectors:
- Quality control: Ensures consistent product density which impacts flavor uniformity, solubility, and consumer satisfaction.
- Packaging design: Optimizes jar and container sizes based on precise density data to maximize shelf space and minimize costs.
- Trade and commerce: Provides a standard basis for calculating volumes in sales agreements and for vending machine calibration, reducing disputes between buyers and sellers.
- Research and development: Assists in formulation adjustments to achieve desired powder flow characteristics and compactability.
- Logistics and storage: Allows more accurate estimation of space requirements in warehousing and transport.
Related Standards
- ISO 787-11: General methods for determining tamped volume and apparent density of powders, referenced within ISO 6770 for jogging volumeter procedures.
- Other ISO standards related to agricultural food products and powder testing, which together support comprehensive quality assessment and product characterization.
Keywords: ISO 6770, instant tea bulk density, free-flow bulk density, compacted bulk density, powder density measurement, jogging volumeter, instant tea packaging, density testing standard, tea powder quality control, ISO standards for tea
