Wort Broth

Wort Broth is used for the cultivation of yeasts.

Composition**

Final pH ( at 25°C) 4.8±0.2

**Formula adjusted, standardized to suit performance parameters

Directions

Suspend 33.28 grams in 1000 ml distilled water containing 2.35 grams of glycerol. Heat if necessary, to dissolve the medium completely. Sterilize by autoclaving at 15 lbs pressure (121°C) for 15 minutes. Mix well and dispense as desired.

Principle And Interpretation

Wort Broth is formulated as described by Parfitt (1) for the cultivation of fungi especially yeasts in syrups and butter. Wort Broth is especially designed to propagate the multiplication of yeasts and often it has been employed as a semi-selective or enrichment medium. Yeast grows well in culture media containing dextrin or maltose in acidic environment.

In this medium peptic digest of animal tissue and malt extract provide nitrogenous and other nutrients for the growth of yeasts. Dextrin and maltose are fermentable carbohydrates. The high acidic pH inhibits many bacteria. Phosphate buffers the medium.

Quality Control

Appearance Light yellow to brownish yellow homogeneous free flowing powder

Colour and Clarity of prepared medium Yellow coloured opalescent solution in tubes that may contain a flocculent precipitate.

Reaction Reaction of 3.33% w/v aqueous solution at 25°C. pH : 4.8±0.2

pH 4.60-5.00

Cultural Response M333: Cultural characteristics observed with added glycerol after an incubation at 25-30°C for 40-48 hours.

Note: *-Formerly known as Aspergillus niger

Storage and Shelf Life

Store below 30°C in tightly closed container and the prepared medium at 2 - 8°C. Use before expiry date on the label.

Reference

1. Parfitt, 1933., J. Dairy Sci., 19 : 141.