GB2143545A

GB2143545A - Improving the nutritive value of products

Info

Publication number: GB2143545A
Application number: GB08417085A
Authority: GB
Inventors: Johann Theodor Grieff
Original assignee: Individual
Current assignee: Individual
Priority date: 1983-07-07
Filing date: 1984-07-04
Publication date: 1985-02-13
Also published as: GB2143545B; ZW10484A1; MW1184A1; GB8417085D0; OA07737A; ZM3684A1

Abstract

The nutritive value of products formed by or with the aid of fermentative organisms is increased by improving the availability for ingestion by humans or animals of the vitamin B content of cells of yeast and other fermentative organisms included in the product by killing such cells. The cells of the fermentative organisms are killed by subjecting the product to mechanical communication in, e.g., a ball-mill type disintegrator, resulting in mechanical rupturing of at least a part of the yeast cells. Alternatively, yeast is separated from freshly brewed beer and subjected to mechanical comminution. The cell debris is separated from the comminuted yeast and the liquid phase is returned to the beer. A percentage of live fermentative cells may be retained in the product, or live cells added to the product, in order to achieve a satisfactory degree of effervescence therein.

Description

SPECIFICATION Improving the nutritive value of products The present invention relates to a process for improving the nutritive value of products formed by or with the aid of fermentative organisms by improving the availability for ingestion by humans or animals of the vitamin B content of cells of yeast and other fermentative organisms included in the product by killing such cells.

More particularly the invention relates to a process for improving the nutritive value of a fermented food, feed or beverage product to be consumed in a state of active fermentation and containing fermentative cells, by killing cells of yeast and other fermentative organisms of the product so as to improve the availability for ingestion by humans or animals of the vitamin B content of the yeast cells or of other fermentative organisms.

Yeast cells have for a long time been considered a valuable source of vitamin B complex compounds, in particular thiamine, riboflavin and niacin (which for the purpose of the present disclosure is used as a generic term for both nicotinic acid and nicotinamide). This is one of the reasons why beverages such as Quass which are consumed in a state of active fermentation are reputed to have a high nutritional value. Mainly for the same reason African traditional beer, and particularly sorghum beer, known in Southern Africa also as "Bantu Beer", Utshwala (Zulu), Joala (Sesotho), Utywala (Eastern Cape tribes) had in the past been considered a highly nutritious substance, mainly because of the relatively high vitamin B content, a high proportion of which is contained in the yeast cells.Traditionally these yeast cells are live in the product as drunk, thus keeping the product in a state of active fermentation until consumed, this being responsible for the fresh slightly efferverscent flavour due to the generation of carbon dioxide.

However it is now recognised that the aforesaid assumption concerning nutritional vaue is not quite correct for two reasons: the yeast cells, depending on the yeast strain, are to a greater or lesser extent incapable of synthesising the vitamin B complex compounds from the brewing liquor (or wort). This is particularly true of the compound thiamine, which is absorbed by all live yeast used in such brewing. To a usually lesser extent this also applies to niacin, whilst riboflavin is usually released to the medium to a greater or lesser extent by live yeast cells. However, all of these vitamins to the extent that they are present in the live yeast or other fermentative cells are trapped in such a manner that they are wholly or substantially unavailable for ingestion by humans or animals.

Because of the presumed high nutritional value of brews of this nature it has even been proposed to use such brews in animal feeding programmes. Because of the non-recognition of the aforesaid problem these experiments were not altogether successful.

In the context mainly of traditional African beer attempts were made to supplement the vitamin B content by the addition of synthetic vitamin compounds. This was not very successful because the live yeast cells absorb the vitamins relatively quickly from the brew.

Once absorbed in the cell the vitamins are nutritionally unavailable.

Accordingly pasteurization was resorted to (South African Patent 81 /1829) to kill the yeast cells, causing the release of the vitamins to the brewing liquor. This however had the disadvantage of stopping the fermentation altogether, resulting in a flat and unpalatable product. Pasteurization is a relatively expensive process which moreover results in some undesirable chemical and physical changes in the components of the brew, possibly also in some damage to the vitamins. To counteract some of these effects, carbonisation (recharging with CO2) and supplementation of the vitamin content of the pasteurized product with synthetic vitamin B compounds was resorted to, an additional cost factor.The problems outlined in the aforegoing are not confined to the brewing of traditional African beer, but are common to all products based on or containing live yeast cells, e.g. concentrates of so-called single cell protein as produced by the fermentation of effluent liquors in paper manufacture and pulping or by the fermentation of sugars obtained by the acid hydrolysis of cellulose or hemicellulose (Scholler-process).

However the problem also applies to various beverages, in particular those intended for consumption in an active state of fermentation, e.g. the Russian beverage known as Quass (of which two versions are known, milk quass and bread quass).

The present invention teaches ways and means for improving the availability for ingestion by humans or animals of the vitamin B content of yeast cells and cells of other fermentative organisms in any of the aforementioned products of similar products by a more advantageous manner of killing the cells to release the vitamins.

In accordance with the present invention the cells of the fermentative organisms are killed by subjecting the product to mechanical comminution resulting in mechanical rupturing of the yeast cells. Such mechanical comminution is preferably brought about by means of a ball mill type of homogeniser apparatus which in the present context performs the function of a cell disruption unit. An example of a suitable type of apparatus is available from the firm Willy A. Bachofen AG, Basel, Switzerland under the trade name "Dyno-mill", the action of which normally results in more than 80% and up to 100% of yeast and the like cell disintegration.An additional advantage of the comminution step is that it also results in the very effective, very fine comminution of gritty ingredients which are normally present in traditional brews of this type, thereby resulting in a product which is very smooth to the palate.

In the context of beverages or products which are to be served in an effervescent condition, i.e. in a state of still active fermentation, it is preferred to so regulate the comminution that a certain percentage of the fermentative cells remains alive and undamaged, e.g. from 40 to 1%, preferably from 30 to 5% e.g. from 25 to 10%. The content of remaining live fermentative cells is so selected that at the expected time of serving there will be a satisfactory degree of effervescence, whilst the ratio of available to non-available vitamin B is maximised. The same effect can also be attained by confining the comminution treatment to only part of the product, more particularly a major part thereof, and setting aside another portion, e.g. a smaller portion and mixing back such portion to the portion subjected to the comminution treatment.Yet a further alternative is to add back to the treated brew a small proportion of separately prepared live fermentative cells, in an amount just sufficient to produce the desired effervescence. Such cells may be of a selected strain, e.g. different from the strain used in the main brewing process, and having a relatively lesser tendency to absorb vitamin B compounds from the liquor.

The process may for example be applied to the manufacture of African traditional beer, Quass, Soma (India) or Booza (Egypt).

However, the process may also be adapted to the manufacture of vitaminised "European" beer intended to be consumed as clear liquids without the introduction of substances foreign to conventional brewing processes. Such a process comprises separating yeast from freshly brewed beer, subjecting a predetermined quantity of the separated yeast to cell disintegration by mechanical comminution and returning the vitamins so liberated to the beer. The yeast cell debris may be separated from the liquid phase containing the liberated vitamins prior to the returning of the vitamins to the beer or during a later stage of solid separation and clarification. The separated yeast may optionally be washed and debittered first before the cell disintegration.

However, it may be preferred for the bittering agents to be recycled to the beer in addition to the bittering agents of the hops extracted by the yeast cells from the beer. This can contribute to economics in consumption of expensive hops.

The thus vitaminised beer may be processed in conventional manner for immediate consumpton or be subjected to lagering or be subjected to after-fermentation and full maturation before packing and consumption. The cell disintegration also releases enzymes which may slightly increase the alcohol conent. If this is not desired the enzymes may be deactivated in any suitable manner.

The scope of the invention is intended to extend to the products of the process as well as to manufacturing plant modified by the provision of mechanical cell comminution equipment and adapted to carry out the process.

The term "comminution" as herein employed is not intended to imply that all or even the majority of cells being ruptured must necessarily be broken up into particles predominently of a smaller order of particle size range than the majority of the intact yeast cells.

Example 1: Milk Quass is passed continuously through a ball mill type cell disintegrating unit of the trade mark Dyno-mill. The retention time is so regulated that 85% of the live cells in the brew are disintegrated and killed. When the brew is served it has its traditional fresh effervescent taste.

Example 2: Bread Quass is prepared in the normal manner and subjected to the treatment described in example 1.

Example 3: Traditional African sorghum beer is brewed by any of the well-known traditional brewing processes. At the end of the brewing process and prior to filling of the liquor into containers for retailing, the product is passed through a ball-mill type of cell disintegrating unit. The residence time is so adjusted that 80% of the yeast cells are killed and disrupted. When the product is sold it is in a state of adequate active fermentation for a desired degree of effervescence. The content of vitamin B available for ingestion is substantially improved.

Example 4: Example 3 is modified as follows: 20% of the brew is set aside and 80% is subjected to complete homogenising in the ball-mill, resulting in virtually complete disruption of the yeast cells. Prior to packaging the untreated 20% of the original brew is added back to and thoroughly mized with the treated 80%.

Example 5: European type hopped and fermenting beers to be consumed as clear liquids are brewed in the conventional manners. The young beer, chilled and ready to leave the fermenting vessel is passed through a yeast centrifuge. The yeasty effluent is washed and debittered and then passed through a cell disintegrating ball mill. Calculated quantitites of the disintegrated product including the li berated vitamins are now recycled as-is to the beer, or after filtration to remove the cell debris. The beer is then either subjected to conventional lagering or, after addition of a selected strain of yeast is stored for a period of after fermentation and full maturation, or immediately passed to the final processing steps preceding packing and consumption.

The final processing comprises filtering or polishing in a pulp filter, followed by "sterile filtration" (e.g. through "Seitz EK" filters).

Such a vitaminised beer contains no ingredients foreign to accepted brewing technology and complies with strict purity and food regulations, e.g. the Bavarian "Reinheitsgebot".

Claims

1. A process for improving the nutritive value of products formed by or with the aid of fermentative organisms by improving the availability for ingestion by humans or animals of the vitamin B content of cells of yeast and other fermentative organisms included in the product by killing such cells, wherein the cells of the fermentative organisms are killed by subjecting the product to mechanical comminution resulting in mechanical rupturing of the yeast cells.

2. Process according to claim 1, wherein the mechanical comminution is brought about by means of a ball mill type of homogeniser apparatus.

3. Process according to claims 1 or 2, wherein the comminution is so regulated that a desired percentage of the fermentative cells remains alive and undamaged.

4. A process according to claim 3 wherein the percentage is from 40 to 1%.

5. Process according to claim 4 wherein the percentage is from 30 to 5%.

6. Process according to claim 5 wherein the percentage is from 25 to 10%.

7. Process according to claims 1 or 2 which comprises confining the comminution treatment to only part of the product, and setting aside another portion, and mixing back such portion to the portion subjected to the comminution treatment.

8. Process according to claim 7 wherein the part subjected to the comminution is larger than the part which is not.

9. Process according to claims 1 or 2 which comprises adding back to the treated brew a small proportion of separately prepared live fermentative cells, in an amount just sufficient to produce the desired effervescence.

10. Process according to claim 9 wherein the cells are of a selected strain, different from the strain used in the main brewing process, and having a relatively lesser tendency to absorb vitamin B compounds from the liquor.

11. Process according to any one of claims 1 to 10, applied to the manufacture of African traditional beer.

1 2. Process according to any one of claims 1 to 10, applied to the manufacture of Quass.

1 3. Process according to any one of claims 1 to 10, applied to the manufacture of Soma.

14. Process according to any one of claims 1 to 10, applied to the manufacture of Booza.

1 5. Process according to claim 1 or 2 applied to improving nutritive value of single cell protein for human or animal consumption.

1 6. A process according to claim 1 or 2, adapted to the manufacture of vitaminised "European" beer, intended to be consumed as clear liquids which comprises separating yeast from freshly brewed beer, subjecting a predetermined quantity of the separated yeast to cell disintegration by mechanical comminution and returning the vitamins so liberated to the beer.

17. A process according to claim 16 wherein the yeast cell debris resulting from the communution is separated from the liquid phase containing the liberated vitamins prior to the returning of the vitamins to the beer.

1 8. A process according to claim 1 6 or 1 7 wherein the separated yeast is washed and debittered first before the cell disintegration.

1 9. A process according to claim 1 substantially as hereinbefore described and exemplified.

20. Products in which the availability of vitamin B complex has been improved by a process as claimed in any one or more of the preceding claims.

21. Manufacturing plant modified by the provision of mechanical cell comminution equipment and adapted to carry out the process as claimed in one or more of claims 1 to 19.