Aeration and Foam Control in Baker's Yeast Production: Mapping Patents

Abstract

A key ingredient in the baking industry, baker's yeast must be produced under strict controlled conditions. High yields of baker's yeast cannot be attained unless a huge quantity of air is injected into fermentation vats. This review of 245 patent specifications shows that inventors have paid much attention to the distribution of fine air bubbles in order to optimize oxygen transfer to the yeast cells. Technical solutions to reduce energy costs associated with aeration are also proposed. Intense aeration caused foaming problems, so mechanical destruction of foam was first proposed until inventions on specific chemical antifoams were patented. In recent years, the development of cheaper and more efficient foam control techniques has remained an issue. Aeration during yeast growth in tanks impairs its fermentative activity in anaerobic bread dough. Since the beginning of the 20th century, massive adoption of air-grown fed-batch baker's yeast probably encouraged sugar addition to stimulate yeast gassing activity in pan bread characterized by high loaf volume, especially those prepared under short dough fermentation conditions.

Compressed Baker's Yeast: Mapping Patents on Post‐Fermentation Processes

“…This review on the last steps of compressed yeast production was performed over a period of about 10 y, in parallel with searches on other aspects of baker's yeast technology (Gélinas , , , ). Searching the older patent literature was a major challenge because more files are continuously made available from online services of intellectual property offices or ancient books emerging on the Internet.…”

“…By 1920, yeast biomass that tended to float on growth media had been replaced by bottom or lager yeast that was more adapted to wheat bread dough fermentation (Gélinas ). Around that period, it also became customary to strongly aerate fermentation media, so more yeast biomass had to be harvested because yields increased much (Gélinas ). Typical fermented wort contained about 2% to 2.5% yeast solids in the early days of baker's yeast manufacturing, compared to 5% to 10% yeast solids in modern baker's yeast plants (Walter ; White ).…”

“…According to this review, such close reading of patents specifications was important to avoid overestimation of patenting activity. Total number of patented inventions on the production of compressed baker's yeast was based on data reported in this review as well as in companion reviews (Gélinas , , , ). That number does not include patents on yeast strains and specialty ingredients for niche markets (Gélinas ), or yeast handling and activation at the bakery plant (Gélinas ).…”

“…DE, Germany (309 patents); US, United States of America (194 patents); AT, Austria (100 patents); GB, United Kingdom (98 patents); FR, France (81 patents); SE, Sweden (73 patents); others (241 patents). In addition to entries reported in Table , data are adapted from Gélinas (, , , ) and include additional entries from Table S1 to S3.…”

“…The aim of this review of the patent literature was to check, on the long term, the interest of inventors for harvesting, cleaning, dewatering, forming, and packaging yeast solids, commercially known as compressed baker's yeast. In addition, evolution of the complete production of compressed baker's yeast is briefly considered, based on companion reviews of patents (Gélinas , , , ). Such information is very useful to understand worldwide market incentives leading to the development of yeast, the very 1st and still the most important microbial starter for food fermentations.…”