This invention relates to baking mixes which contain flour and have an enhanced shelf life and to a method and means for preparing same, More particularly the invention is concerned with the inhibition of spoilage bacteria in such mixes using a substantially naturally produced composition.
Although the invention relates in general to the enhancement of the shelf life of baking mixes which contain flour, it has particular application to confectionery pre-bakes and especially to muffin batter. Such batters generally comprise a mixture of flour and beaten egg, typically with milk or water added. They are generally placed in a suitable shaped container and exposed to heat for cooking, usually referred to as baking.
In many catering applications, between a baking mix preparation stage and the eventual cooking stage, there is often a lengthy delay. This results from the practicalities of the food industry in which batch processes for the preparation of baking mixes are generally followed if not by reason of practical necessity then at least for reasons of convenience. Also, economies of scale favour the preparation of larger batches rather than smaller ones and in consequence a mix may be required to stand or be stored before ultimate use. In this precooking delay, spoilage producing micro-organisms and harmful pathogens tend to develop, often leading to a rather limited shelf life.
Conventional batter preservation methods aim at xe2x80x9cimmobilizingxe2x80x9d spoilage producing microbial species present in constituents added to a mix, freezing being one of the most common of these. Lengthy periods of freezing are however known to cause deleterious effects in such mixes, such as an adverse effect on the physical structure of the crystals and other properties determining the texture of the baked product. Irrespective of this, the transport and storage of frozen mixes is costly and requires considerable storage space. Other shelf life enhancing synthetic substances have been proposed and are available on the market but are not, as far as applicant is aware, popular for a number of different reasons not least of which is the general tendency away from synthetic substances.
It is an object of the present invention to provide a substantially natural method and means for inhibiting the growth of spoilage bacteria in baking mixes which contain flour.
According to a first aspect of the invention there is provided a microbial species described as Lactobacillus plantarum/pentosus and assigned the accession number PTA-1466 at the American Type Culture Collection (ATCC) (the strain being hereinafter referred to as the LPP strain).
The deposit referred to above was made at
American Type Culture Collection
10801 University Boulevard
Manassas
VA 201 10-2209
United States of America
on Mar. 6, 2000.
According to a second aspect of the invention there is provided a method of preparing a shelf life enhancing composition for baking mixes which contain flour, the method comprising forming a starting mixture including flour and water and inoculating same with a culture of the LPP strain micro-organisms; allowing the mixture to ferment in order to produce anti-microbial substances including lactic acid, a peptide and possibly other presently unidentified anti-microbial substances; and terminating the fermentation process and destroying all living cells prior to the pH of the mix decreasing to 3.3 to yield a shelf life enhancing composition.
Further features of this aspect of the invention provide for the starting mixture to include glucose in order to expedite the fermentation process in which case the glucose is preferably present in an amount of about 1% m/v; for the fermentation to be carried out at a temperature of from 33 to 35xc2x0 C.; for the fermentation to be terminated at a pH of about 3.4; for the fermentation process to be terminated by heat treating the mixture at a temperature of not more than 80xc2x0 C. and preferably about 70xc2x0 C.; and for the temperature of the product shelf life enhancing composition to be lowered to from 3 to 8xc2x0 C. and preferably to about 4 or 5xc2x0 C. for transport and storage purposes.
The invention also provides a shelf life enhancing composition produced by a method as defined above.
In order to produce a culture for use in the production of the shelf life enhancing composition defined above the LPP strain is inoculated into MRS (De Man Rogosa and Sharpe) broth (sold by Merck, Darmstadt, Germany) from colonies growing on MRS Agar (also sold by Merck) and incubated for a suitable period of time, generally from 48 to 72 hours at 30xc2x0 C. without aeration.
In accordance with a third aspect of the invention there is provided a baking mix comprising a major amount of a bulk mixture including at least flour and water (which term includes milk for this purpose) and a minor amount of a shelf life enhancing composition as defined above.
The baking mix may, in particular, be a batter, and more particularly, but in no way exclusively, a muffin batter mix.
The proportion of the shelf life enhancing composition to the bulk mixture will depend on the objective to be achieved, the way in which the shelf life enhancing composition was prepared and the nature of the bulk mixture. In the case that the fermentation process was terminated at a pH of about 3.4, as a general rule, an amount of shelf life enhancing composition of about 14 to 16% (w/w) of the total baking mix will generally be effective.
It will however be appreciated by those skilled in the art, that individual situations will dictate their own optimal conditions both as to the manner in which the shelf life enhancing composition is prepared and in the proportions of that composition relative to the total baking mix that are to be used in order to achieve a desired objective and to provide a required degree of efficacy.
In order that the invention may be more fully understood one form of implementation thereof will now be described as well as the derivation of the particular strain of microbiological species forming the basis of the invention.