Potato Dextrose Agar Lab Report

Potato Dextrose Agar

1. 39.0 g of potato dextrose agar powder was dissolved in a litre of sterile distilled water on the hot plate.

2. pH of the solution was adjusted to 5.6 ± 0.2 by adding NaOH or HCl and was immediately transferred into the Schott bottle to be autoclaved at 121 ° C for 15 minutes

3. Prepared medium was stored in 4° C chiller

Plate Count Agar or Total Plate Count

1. 22.5 g of plate count agar powder was dissolved in a litre of sterile distilled water on the hot plate

2. pH of the solution was adjusted to 7.0 ± 0.2 by adding NaOH or HCl and was immediately transferred into the Schott bottle to be autoclaved at 121 ° C for 15 minutes

3. Prepared medium was stored in 4° C chiller

Lauryl Sulphate Broth

It is a solution that maintains the osmotic balance for bacteria. It also used in the microbial control of apparatus by the rinse and swab method.

Stomaching process used in this experiment offers as a useful alternatives to blending in preparing food samples for microbiological analysis but according by data presented om 30 types of food tested, the efficiency of stomachers varies based on the type of food being examined. Since most of the pineapple products tested is either in liquid or semi-solid form, stomaching is the most suitable way to make food homogenate(Andrews et al, 1977). Besides that, in this analysis process we used serial dilution method. Serial dilution is the repeated dilution of a solution to amplify the dilution factor quickly. It is commonly performed in experiments requiring highly dilute solutions with great accuracy such as those involving concentration curves on a logarithmic scale or involving experiments to determine density of bacteria

Following are the parameter analysis:

Fixed standard Quality Standard

Net weight Depth of Color

Vacuum Uniformity of Color

Headspace Uniformity of Cut

Syrup Strength Absence of Defect

Number of Pieces Texture

Drained Weight Flavour Clarity of Medium

DETERMINATION OF NET WEIGHT

Weight all the canned pineapples using weighing machine. Note the reading on the top of the can and record in the column of net weight on worksheet “BBatch Sampling and Grading Report”. If the value of net weight less than specified range, which noted on Pineapple Industry (Grading, Labelling and Marking Regulations 1959), it is classified as downgraded

Table 3:Net weight range based on Pineapple Industry(Grading, Labelling and Marking Regulations 1959)

Size of Can Maximum(gram) Minimum(gram)

211 × 301 227 220

211 × 400 284 277

211 × 414 383 377

301 × 310 341 334

401 × 212 454 447

301 × 409 454 447

307 × 408 567 560

401 × 411 794 780

404 × 700 1220