Food or edible material: processes – compositions – and products – Fermentation processes – Of farinaceous cereal or cereal material
Reissue Patent
2002-06-28
2004-04-27
Paden, Carolyn (Department: 1761)
Food or edible material: processes, compositions, and products
Fermentation processes
Of farinaceous cereal or cereal material
C426S061000, C426S062000, C426S063000, C426S549000, C426S064000, C426S019000
Reissue Patent
active
RE038507
ABSTRACT:
FIELD OF INVENTION
The present invention relates to a process for retarding the staling of bread and similar baked products, as well as an agent for use in the process.
BACKGROUND OF THE INVENTION
Staling of baked products, principally bread, has been ascribed to certain properties of the starch component of flour. Starch is essentially composed of amylose forming the core of starch granules and amylopectin forming the outer “envelope” of starch granules. Starch suspensions have been observed to retrograde on standing to precipitate the amylose which, by some, has been given as the explanation of the phenomenon of staling. Others have explained staling of bread in terms of the amylopectin chains in starch associating to cause a greater rigidity of the bread crumb which is characteristic of stale bread.
It is generally recognized to be of some commercial importance to retard the staling of baked products so as to improve their shelf-life. Retardation of the staling process may, for instance, be brought about by the addition of monoglycerides to dough. The antistaling effect of the monoglycerides may partly be ascribed to their ability to bind water and partly to the formation of monoglyceride-amylose complexes wherein the long hydrocarbon chain penetrates into the cavity of the amylose helix and thereby stabilise the helical structure to prevent retrogradation.
Enzymatic retardation of staling by means of &agr;-amylases has also been described, vide for instance U.S. Pat. No 2,615,810 and U.S. Pat. No. 3,026,205 as well as O. Silberstein, “Heat-Stable Bacterial Alpha-Amylase in Baking”, Baker's Digest 38(4), August 1964, pp. 66-70 and 72. The use of &agr;-amylase for retarding the staling of bread has, however, not become widespread. The reason for this is assumed to be that the medium-molecular weight branched compounds, termed maltodextrins (with 20-100 glucose units in the molecule), generated through the hydrolytic action of &agr;-amylases have a sticky consistency in themselves resulting in the formation of a sticky or gummy crumb, and consequently an unacceptable mouthfeel, of the baked product if the &agr;-amylase is overdosed so that the maltodextrins are present in excessive quantities.
It has previously been suggested to remedy the deleterious effects of very large doses of &agr;-amylase added to dough by adding a debranching enzyme such as pullulanase, cf. U.S. Pat. No. 4,654,216, the contents of which are incorporated herein by reference. The theory behind the addition of a debranching enzyme to obtain an antistaling effect while concomitantly avoiding the risk of producing a gummy crumb in the resulting bread is that by cleaving off the branched chains of the dextrins generated by &agr;-amylase hydrolysis which cannot be degraded further by the &agr;-amylase, the starch is converted to oligosaccharides which do not cause gumminess.
SUMMARY OF THE INVENTION
The present invention represents a different approach to the problem of crumb gumminess likely to result from the excessive use of &agr;-amylase for retarding the staling of bread. Thus, the present invention relies on the use of an enzyme which is capable of retarding the staling of baked products but which does not hydrolyze starch into the above-mentioned branched dextrins.
It has surprisingly been found that when the enzyme added to dough used for producing baked products is an exoamylase, an antistaling effect is obtained whereas the formation of a sticky or gummy crumb is substatially avoided except at very high levels of the enzyme which also give rise to other deleterious effects likely to be discovered when the baked products are subjected to quality control.
It was also found that by using exoamylase enzymes one avoids a certain softness and stickiness of the dough which is often encountered when &agr;-amylases, especially fungal &agr;-amylases, are used for antistaling, and especially if the &agr;-amylase has been overdosed, even if only to a mild degree.
Accordingly, the present invention relates to a process for retarding the staling of leavened baked products, which process comprises adding an enzyme with exoamylase activity to flour or dough used for producing said baked products. In the following, this enzyme is usually referred to as an “exoamylase”.
In another aspect, the present invention relates to a baked product produced by the present process.
It will often be advantageous to provide the exoamylase in admixture with other ingredients commonly used to improve the properties of baked products. These are commonly known as “pre-mixes” and are employed not only in industrial bread-baking plants/facilities, but also in retail bakeries where they are usually supplied in admixture with flour.
Hence, in a further aspect, the present invention relates to an agent for improving the quality of leavened, in particular yeast leavened, baked products, which agent comprises an enzyme with exoamylase activity in liquid or substantially dry form. For the present purpose, such an agent will be termed a “bread improver” in the following description although it will be understood that it may also be used for addition to other types of leavened baked products such as rolls, certain kinds of cakes, muffins, buns, etc.
DETAILED DISCLOSURE OF THE INVENTION
Exoamylases are enzymes which hydrolyse (1−<4) &agr;-glucosidic linkages in starch (and related polysaccharides) by removing mono- or oligosaccharide units from the non-reducing ends of the polysaccharide chains. The reducing groups liberated from the polysaccharide molecule may be in the &agr;- or &bgr;-configuration. Examples of exoamylases which are useful for the present purpose are glucoamylase, &bgr;-amylase (which releases maltose in the &bgr;-configuration) and maltogenic amylase (which releases maltose in the &agr;-configuration, but in contrast to &agr;-amylases predominantly produces maltotriose and maltotetraose and only minor amounts of higher oligosaccharides). The antistaling effect of adding exoamylase to dough is currently believed to be ascribable to the formation of sugars with a high water retention capacity which makes the baked product in question appear fresh (soft) for longer periods of time (e.g. glucose, maltose, maltotriose and/or maltotetraose), as well as to the modification of the native starch which reduces the tendency to retrogradation. Overdosing with the exoamylase resulting in crumb stickiness is less likely to occur because the formation of branched maltodextrins with 20-100 glucose units to which the stickiness may be ascribed is, if not completely avoided, at least significantly lower than when using &agr;-amylase.
The use of amylase (primarily &agr;-amylase), invertase and poly-saccharidase, as well as glucosidase (an exoamylase)) is suggested in EP 136 158 and EP 136 159 for the preparation of cookies with a moist crumb structure. Amylase is capable of forming crystallization-resistant sugar, which is able to bind water, from one or more ingredients in the dough resulting in the aforementioned moist crumb when the dough is subsequently baked. The cookies are indicated to be storage-stable.
It appears that the selection of the enzyme according to EP 136 158 and EP 136 159 is made with the object of obtaining a moist crumb structure due to the formation of water-binding sugars from starch. With this end in view, pregelatinized starch is added to the dough to facilitate enzymatic hydrolysis into various sugar species. It further appears that the risk of obtaining a gummy crumb in the baked product through addition of too large an amount of a-amylase is not a problem to be avoided, but rather that moistness of the baked crumb is the end result which the inventions disclosed in the above-mentioned EP applications intend to achieve. In fact, &agr;-amylase which is known to produce crumb gumminess in leavened bread even when added in relatively low quantities is the preferred enzyme according to EP 136 159, the branched maltodextrins produced by the &agr;-amylase apparently providing satisfactory moisture character
Garbell Jason I.
Lambris Elias J.
Novozymes A/S
Paden Carolyn
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