ASTM D7816-23 PDF

Overview

ASTM D7816-23 outlines a standard test method for the enumeration of halophilic (salt-tolerant) and proteolytic (protein/collagen-hydrolyzing and salt-tolerant) bacteria in raceway brine, brine-cured hides and skins, and pre-charge raceway liquor. The method helps identify and quantify bacteria known to cause damage to hides and skins during brining. Developed under the jurisdiction of ASTM Committee D31 on Leather, this international standard supports quality assurance and microbiological control in industries handling brine-treated animal products.

Key Topics

• Enumeration of Bacteria: The standard details procedures for preparing samples, serial dilutions, plating on selective media, incubation, and colony counting to quantify halophilic and proteolytic bacteria.
• Sample Types: Applicable to raceway brine, brine-cured hides and skins, and pre-charge raceway liquor.
• Colony Differentiation: After incubation, all colonies are counted to determine halophilic bacteria. Plates are then treated with acetic acid, and colonies with semi-clear zones (“halos”) are identified as proteolytic.
• Standardized Approach: Utilizes SI units exclusively, with instructions for sample handling, equipment, reagents, and safety precautions.
• Repeatability: Includes guidance on repeatability limits based on interlaboratory studies, ensuring consistent and reliable results within the same laboratory.

Applications

ASTM D7816-23 offers practical value across multiple sectors involved in the handling, processing, and inspection of animal hides and skins:

• Leather Industry: Used for quality inspection and microbial control in brine-curing facilities to minimize spoilage caused by salt-tolerant, proteolytic bacteria.
• Brine Treatment Plants: Assists in monitoring and optimizing bacterial levels in raceway brine to ensure integrity and value of skins prior to further processing.
• Research Laboratories: Provides a reliable microbiological method for scientific studies involving salt-tolerant bacteria and their impact on collagen-containing materials.
• Regulatory Compliance: Supports adherence to industry standards and helps meet national and international regulatory requirements for hide and skin preservation.
• Environmental and Quality Control: Enhances programs aiming to reduce waste and product loss due to microbial deterioration.

Related Standards

When using ASTM D7816-23, consider its relationship to the following standards and practices:

• ASTM D6715: Practice for Sampling and Preparation of Fresh or Salt-Preserved (Cured) Hides and Skins for Chemical and Physical Tests.
• ASTM E177: Practice for Use of the Terms Precision and Bias in ASTM Test Methods.
• ASTM E691: Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method.

These related standards provide additional guidance on sampling, terminology, and method validation, supporting a robust approach to bacterial enumeration and quality testing in hide and skin preservation.

Keywords: ASTM D7816-23, halophilic bacteria, proteolytic bacteria, enumeration, brine-cured hides, raceway brine, bacterial testing, salt-tolerant organisms, leather industry, microbial control, quality assurance, standard test method.