Spent brewer’s yeast is the second largest by-product generated by the brewing industry. The term “spent brewer’s yeast” is used to describe yeast that is surplus to the brewer’s needs or is no longer needed in the brewing process.
1. Introduction
The production of yeast spreads from brewer’s spent yeast commences with the selection of an appropriate quality of spent brewer’s yeast that is substantially free of bacterial contamination and extraneous materials such as filter aids and excessive hops flavours and aromas. The yeast extract processing plants require a reasonably consistent supply of spent brewer’s yeast in terms of dry weight, residual sugar and ethanol. Some producers of yeast extract allow the yeast to grow on a sucrose substrate in order to achieve sufficient supply of raw spent yeast and as a mean to reduce residual hops components
[3][1]. The typical production is as follows: the spent yeast slurry is heated and salt and enzymes are added after which the hydrolysis process proceeds at 63 °C during which yeast enzymes facilitate the hydrolysis of various yeast cell components. The additional enzymes permit particular hydrolytic reactions to be emphasised in order to speed up and steer the hydrolytic process towards specific quality parameters. Following the hydrolysis process much of the yeast cell wall particulates are removed. The remaining liquid is concentrated by means of a rotary drum filter and multi-stage vacuum evaporators after which spices can be added to finish off the flavour profile
[9][2]. This produces a relatively fluid product whilst the pastier yeast extracts tend have yeast cell wall materials added back in to achieve the desired consistency required for a spreadable product
[3][1].
2. Recognition and “Iconic” Status of National Yeast Spread Brands
When approached by the researchers, all passers-by recognised the jar of yeast spread shown to them. In the UK, 44% of passers-by indicated that they “loved” the product, while that proportion was 43% and 71% in New Zealand and Australia, respectively (
Table 31),
X2 = df 4,
n = 1173, CV = 84.91,
p < 0.001. When asked whether the brand was “iconic” in relation to their country, 99% of Australians answered “yes”, 84% of New Zealanders answered “yes” and 61% of Brits answered “yes”.
Table 31. Recognition and “iconic” status of national yeast spread brands.
|
United Kingdom n = 702 |
Australia n = 249 |
New Zealand n = 222 |
Recognition of national yeast spread brand |
100% |
100% |
100% |
“love” the product |
44% |
71% |
43% |
“hate” the product |
28% |
5% |
19% |
Neither “love” or “hate” |
28% |
24% |
38% |
Assigns iconic status to brand |
61% |
99% |
84% |
3. Awareness of Other (National) Yeast Spreads Brands
All participants were asked whether they were aware of a number of other yeast spread brands. In the first instance this was carried out by showing the passers-by pictures of four other yeast spreads. In the UK nearly 72% of people recognised Vegemite and 27.4% of the passers-by had consumed Vegemite (
Table 42). About 11% of Brits thought that Vegemite tasted nicer than the UK Marmite, while 23% disliked the taste of Vegemite, the remaining ⅔ of Brits thought that Vegemite either the same or just “different, but OK”. Among the Brits, only a small proportion of people though that the New Zealand Marmite tasted nicer than the UK Marmite, while more than half disliked the taste of the New Zealand Marmite. Only a very small proportion of Brits indicated that they ever consumed Promite, and those that did overwhelmingly indicated that Promite taste “different, but OK”. None of the Brits ever tasted the Swiss Cenovis (
Table 42).
Table 42.
Awareness and consumption of other (national) yeast spreads brands in the United Kingdom (
n
= 702).
Other Brands |
Vegemite |
Marmite (NZ) |
Promite |
Cenovis |
Aware of * |
71.7% |
6.4% |
3.1% |
0.9% |
Have previously consumed * |
27.4% |
2.7% |
2.1% |
0% |