The Art of Fermentation

On February 27, 2020, Lallemand hosted its second yeast training program for professional bakers. Aimed to educate bakers about the different varietals of yeast, the seminar also offered its own Baking Training Certificate to its participants.

Over twenty bakeries from Canada and the US attended the Humber College facility to learn about various yeast varieties and methods for helping over-proofed dough, or extending the retarding process for various products.

It began with Lallemand’s history: The Montreal-based company began producing baker’s yeast in 1923. Lallemand now has production plants around eastern and western Europe, the Mediterrean, and commercial distribution that extends to the US. While Lallemand offers yeast and bacteria applications that apply to a variety of functions that include brewing, animal nutrition and confectionery, the focus remained on fermentation for food applications.

How many varieties of yeast are there?

Cream yeast: Convenient for automatic bakery lines, as there is no packaging material to handle and reduces packaging waste.

Advantages: Cream yeast is known for better dispersion in dough and handles itself better in dough machines. It has a shelf life of 2-4 weeks. The substitution ratio is 1,5 litre cream yeast is equal to 1kg compressed yeast.

Disadvantages: Storage and cleaning facilities are expensive, and cream yeast is very sensitive to contamination: Microbiological supervision is required, as well as agitation to avoid decantation.

Block or Compressed yeast: It is obtained from an additional process after cream yeast: Block yeast is simply cream yeast compressed into blocks.

Mainly used for economical and practical reasons in industrial countries.

Advantages: Block yeast doesn’t require any specific conditions of use versus dried yeast. Contrary to generally accepted ideas, it’s undamaged when exposed to salt.

Disadvantages: – Block yeast can lose water during storage and requires quality packaging material to avoid dehydration. Another consideration is logistics (water content and refrigeration costs.)

Crumbled yeast: Advantage: It’s Easier to use on automatic lines as it is free-flowing); doesn’t require any specific conditions of use. It is easier to dilute into water compared to block yeast.

Disadvantages: Sensitive to oxygen and temperature: Crumbled yeast risks heating up and caking. Lallemand recommends avoiding storing yeast in an open bag at ambient temperature: Temperature can rise from 41°C to 120°F within a few hours.

Dry yeast: It is obtained by extruding fresh yeast into vermicelli and is dried. The yeast remains dormant in this dry format, and activated when in contact with moisture during mixing. Vermicelli strands are about 1.5 mm length, 0,5mm diameter and are obtained by fluid bed drying.

Advantages: – No need to rehydrate prior to mixing and it is easier to transport and store.

Disadvantages: Cost of packaging is more expensive. It is not recommended for frozen dough. Dry yeast must avoid contact with cold water or ice.

Recommended direction involves blending it with flour before adding cold water or ice into the dough after slow mixing to ensure ice is totally melted. Dry yeast doesn’t dissolve in dough if using high speed mixer.

After a brief history of the discovery of yeast (bread making started in Egypt roughly 5000 yeas ago) the seminar moved on to the structure of yeast cells, and how they are mass produced for industrial baking applications. Did you know the steps break down to only three steps in its stages?

1. Slant – initial few pure cells inoculated from a small vial to a sterile flask of yeast “broth.” This is followed by 24 hours of incubation at 32C.
2. From the flask, it is transferred into a larger vessel.
3. It then undergoes several fermentation stages with fermenters of increasing volume.

Eventually, the discussion ran towards the “flavour wheel” – how yeast can contribute notes to bread that are similar to wine. Notes like woodiness, citrus and even spiciness can be registered in a finished bread product.

Aside from flavours, the nutritional value of yeast was discussed as to what its range of B vitamins it adds to various products.

The Lallemand team including a nutritionist walked the attendees through the flavours in various breads, and it was interesting to note what yeast can also bring, both in nutrition and culinary value, to the table.