Analysis Total Plate Count in Non Dairy Creamer

1. Principle

Method used bacterial culture plates of dry medium and cold H2O – soluble gel. Diluted test suspension are added to plates at a rate of 1.0 mL per plate. Pressure, when applied to plastic spreader placed on overlay film, spreads test portion over ca 20 sq.cm growtn area. Gelling agent is allowed to solidify and plates are incubate and then counted.

2. Scope

Analysis Total Plate Count in Non Dairy Creamer by Petrifilm Aerobic Count Plate method.

3. Reference

AOAC Official method 989.10 – Bacterial and Coliform Counts in Dariy Products – Dry rehyratable Film Methods

4. Appartus and Reagent

Petrifilm Aerobic Count Plates
Plastic spreader – designed to spread test portion evenly over plate growth area.
Balance có độ phân giải 0.01g
Pipets – Calibrated for bacteriological use to deliver 1.0 mL.
Dilution pepton (water) - aseptically

5. Preparation of test suspensions

Aseptically prepare 1:10 dilution (11 g/ 99 mL dilution pepton). Mix well and plate. Prepare additional dilutions as required. Ordinarily, 1:10 and 1:100 dilutions are sufficient.

6. Analysis

Use dry-film aerobic count plates. Place plate on flat surface. Lift top film and inoculate 1 mL test suspension onto ceter of film base.
Carefully roll top film down onto inoculum. Distribute test suspension over prescibed growth area with downward pressure on center of plastic spreader device.
Leave plate undisturbed 1 min to permit gel to solidify.
Incubate plate 48 h ± 3 h at 320C ± 10C.
In incubator, place plate in horizontal postion, clear side up, in stacks not exceeding 20 units.

7. Result

Magnifier – illumination may also be used to facilitate counting.
Colonies stain in various shades of red. Count all colonies in countable range.
To compute bacterial count, multiply total number of colonies per plate (or average number of colonies per plate if counting duplicate plates of same dilution) by reciprocal of dilution used.

other methods

10.04.2025

Determination protein in non dairy creamer by kjeldhal method

The sample is digested in H2SO4, using CuSO4.5H20 as catalyst with K2SO4, to release nitrogen from protein and retain nitrogen as ammonium salt. Concentrated NaOH is added to release NH3, which is distilled, collected in H3BO3 solution, and titrated in HCl.