MY40G Agar (40% Glucose Malt Yeast Extract Agar)
MY40G Agar (40% Glucose Malt Yeast Extract Agar)
ISO 16087 Reference Medium for Xerophilic Fungi
Catalog Number: AS-1302
Overview
MY40G Agar is a high–osmotic pressure solid culture medium specifically designed for the detection, isolation, and enumeration of xerophilic (extremely osmotolerant) fungi. It is particularly effective for food-spoilage moulds such as Eurotium spp., Xeromyces bisporus, Chrysosporium spp., Wallemia sebi, and selected Aspergillus and Penicillium species.
The medium is the official reference medium specified in ISO 16087 for microbiological examination of low water activity foods and is widely used in food, beverage, and confectionery microbiology.
Applications
• Detection of xerophilic spoilage fungi in sugar-rich, low-aw products
• Testing of dried fruits, jams, syrups, confectionery, spices, nuts, and bakery fillings
• Official reference medium for ISO 16087:2013
• Quality control of raw materials with low water activity (aw 0.60–0.75)
• Preservative-resistant mould (PRM) testing
Key Features & Benefits
• 40% glucose creates high osmotic pressure and low water activity
• Strongly inhibits non-xerophilic fungi and bacteria
• Yeast extract and malt extract support osmotolerant mould growth
• Enables recovery of slow-growing xerophilic species
• Internationally recognised standard for low-aw food microbiology
Principle of the Medium
The high glucose concentration (40%) reduces water activity to approximately aw 0.89, selectively inhibiting non-xerophilic microorganisms. Xerophilic and osmotolerant fungi are able to grow under these conditions. Yeast extract and malt extract provide essential nitrogen, vitamins, and growth factors, supporting the development of slow-growing spoilage moulds commonly associated with low-moisture foods.
Typical Composition (per litre)
Glucose (anhydrous) – 400.0 g
Malt Extract – 10.0 g
Yeast Extract – 2.5 g
Agar – 12.0–15.0 g
Final pH: 5.5 ± 0.2 at 25 °C
(No pH adjustment required)
Preparation
Dissolve malt extract (10 g) and yeast extract (2.5 g) in approximately 600 mL purified water.
Slowly add 400 g glucose with gentle heating and continuous stirring until dissolved.
Add agar and adjust volume to 1 L with purified water.
Sterilise by autoclaving at 115 °C for 10 minutes only.
Do not autoclave at 121 °C, as caramelisation and water activity changes may occur.
Mix thoroughly while warm and pour plates.
Incubation
Incubate at 25–27 °C for up to 30 days.
Examine plates weekly.
Xeromyces bisporus may require 4–6 weeks for visible growth.
Typical Colony Appearance (14–30 days)
Eurotium spp. (Aspergillus glaucus group): yellow-green to blue-green ascomata
Wallemia sebi: dark brown, leathery, wrinkled colonies
Chrysosporium spp.: white to cream, powdery colonies
Xeromyces bisporus: very small, slow-growing, translucent to orange colonies
Storage & Stability
Prepared plates: Store at 2–8 °C, sealed to prevent moisture loss
Use within 4 weeks for optimal performance
Intended Use
For food microbiology and low water activity product testing only.
Not for human, veterinary, pharmaceutical, or therapeutic use.
Quality & Compliance
Manufactured under controlled conditions to ensure batch-to-batch consistency.
Meets performance expectations of ISO 16087 reference methodology.
Performance comparable to leading international food microbiology media suppliers.
Customs & Trade Information
HS / AHECC Code: 3821.00.00
Prepared culture media for the development or maintenance of microorganisms