Agar powder (agar), also known as amaranth, frozen powder, agar or cold weather, is a kind of algin glue extracted from stone cauliflower and other red algae plants. Because of its special gel properties, it has been widely used in food. , medicine, chemical, textile, national defense, biological research and other fields. Using special gel properties, the product can be used as a coagulant, suspending agent, emulsifier, preservative, laxative, and excipient in addition to being directly consumed as jelly. , biological media, convective immunoelectrophoresis and layer split folding vectors.
| Table 1 Comparison of bacterial agar quality at home and abroad | ||||||
| project | 071218B | 80106 | 80302 | 80907 | 60815 | 214510 |
| Moisture (%) | 13.64 | 14.12 | 10.63 | 14.18 | 9.02 | 15.38 |
| PH value | 6.4 | 6.9 | 6.8 | 6.8 | 7.1 | 6.7 |
| Gel strength (g/cm2) | 620 | 720 | 660 | 720 | 560 | 540 |
| Solidification temperature (°C) | 37 | 36 | 38 | 38 | 35 | 42 |
| Dissolution temperature (°C) | 84 | 89 | 76 | 84 | 80 | 82 |
| Phosphate turbidity (50 ° C) NUT | 12.6 | 67.6 | 38.5 | 52.3 | 17.5 | 29 |
| Turbidity (50 ° C) NUT | 15.2 | 67.5 | 85.6 | 43.7 | 4.79 | 11 |
| Phosphate precipitation | no | no | no | no | no | no |
| Use concentration (g/L) | 15 | 15 | 15 | 15 | 15 | 15 |
| 1.5% nutrient agar gel strength | 900 | 720 | 660 | 740 | 540 | 540 |
Reference (China's microbial culture medium agar standard study, Zhao Hongda et al. published in the "Chinese Pharmacy", 2010, Volume 24, No. 6 article) through some agar test results comparison, due to different implementation standards, microbial culture media using domestic The difference between agar powder and imported agar powder is as follows:
1. Domestic agar powder is far from foreign products in terms of dissolved turbidity and phosphate turbidity.
2, domestic agar powder moisture is between 10% ~ 15%, there is a certain gap with imported agar powder, imported agar powder water <10% (Spanish imported bacteriological agar powder water is generally around 8%) . Although turbidity and moisture do not have a large effect on bacterial production, they have a great influence on the appearance of the medium. Excessive moisture is not conducive to the preservation of agar. Agar is stable under neutral or alkaline conditions, and acidity is easily degraded. Especially in the state of high moisture content, the agar gel strength will accelerate degradation with the prolongation of storage time.
3. Domestic agar is stronger than foreign products in terms of gel strength and pigmentation. Since the amount of solid culture agar is between 10% and 18%, the gel strength is high and the cost can be reduced.
Spanish pronadisa bacteriological agar powder technical parameters:
[Technical indicators]
Appearance milky white powder
Moisture <10%
Ash content ≤6.5%
Gel strength (1.5%) 600 – 750 g/cm2
pH before autoclaving (1.5%) 7.0±0.4
After autoclaving pH (1.5%) 6.5 ± 0.4
Melting point (1.5%) 85±5°C
Gel point (1.5%) 35±3°C
Transparency (1.5%) ≤ 12NTU
Colorimetric method (absorbance) 430mm ≤ 0.2
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