ISI 30-2e Determination of Heat Resistant Spore Count
ISI 30-2e Determination of Heat Resistant Spore Count 1. Scope The method is applicable to granular starch in native or modified form. LT 18 Dec 1964 Rev.: LT 30 Aug 1999 2. Principle The sample is serial diluted, incubated on peptone substrate, pasteurised and incubated 3. Apparatus 3.1 Electrical heated incubator thermostatically controlled 3.2 Pipette 2000 -3000 microlitre with disposable tips or glass pipette 3.3 Pipette 500 microlitre with disposable tips or glass pipette 3.4 Laboratory balance 3.5 Flask with wide opening, 100 ml. 3.5 Substrate tubes 160 mm x 16 mm with cap use sterile disposable 3.7 Autoclave Sterilise at 120 +/- 2 o C 20 min. 3.8 Bunsen burner Work antiseptically throughout 4. Media 4.1 Peptone milk. Preparation of peptone milk 10 g peptone is dissolved in ½ litre fresh skimmed milk. Use heating as necessary. Cool and add up to 1 litre with skimmed milk. Add 10 ml 1% solution of bromcresolpurpur in alcohol. Dissolve 0.8 g cysteinhydrochloride in a small q