Food or edible material: processes – compositions – and products – Fermentation processes – Of farinaceous cereal or cereal material
Reexamination Certificate
2001-08-03
2003-10-21
Hendricks, Keith (Department: 1761)
Food or edible material: processes, compositions, and products
Fermentation processes
Of farinaceous cereal or cereal material
C426S064000, C426S549000
Reexamination Certificate
active
06635289
ABSTRACT:
BACKGROUND OF INVENTION
1. Field of the Invention
The present invention relates to a method for retarding the staling of baked goods, and more particularly to a method for achieving the thermal protection and sustained release of a certain enzyme throughout a baked good during and following the baking process.
2. Description of the State of Art
The phenomenon of bread staling has been studied extensively and a variety of theories have been presented. It is now generally accepted that staling is due to a gradual transition of starch from an amorphous structure to a partially crystalline state. This increase in starch crystallinity, also referred to as retrogradation, is caused by an intermolecular or intramolecular association via hydrogen bonding of the two polysaccharides, amylose and amylopectin, which comprise starch granules.
Amylose is made up largely of unbranched chains of D-glucose units (100-1,400 units) which are joined together by alpha-(1,4)-glucosidic bonds. Retrogradation of amylose is rapid due to the ease of alignment of the linear molecules. Amylopectin is the main constituent of starch and, like amylose, it is also constructed from D-glucose units, but in the case of amylopectin they are assembled in shorter, rather bush like, branched chains, containing only 20-25 units of D-glucose. The links in the chain are alpha-(1,4)-glucoside bonds, while the branching points involve alpha-(1,6)-glucosidic bonds. The branched structure of amylopectin interferes with molecular alignment, and consequently amylopectin retrogradation occurs at a much slower rate.
During baking, starch granules swell and absorb moisture, but gelatinization is not complete because of limited water availability. As the granules swell, amylose and to a lesser extent amylopectin diffuse from the granules into the interstitial volume. The solubilized linear molecules retrograde rapidly and form a crystalline network which in combination with the gluten matrix form the characteristic “crumb set” or structure of bread and other baked goods.
Staling of baked goods is generally defined as an increase in crumb firmness and a corresponding loss in product freshness. Flavor, aroma, texture, perceived moisture level, and other product characteristics are also negatively affected as staling proceeds. The staling process begins as soon as baking is complete. Amylopectin remains mostly in the starch granule and retrogrades slowly during product storage. Retrogradation occurs by intermolecular and intramolecular association of linear segments, and to a lesser extent between amylopectin and amylose at the interface of the starch granules and the interstitial volume. As amylopectin retrogradation proceeds, a three-dimensional crystalline structure is formed slowly, causing an increase in firmness, or staling.
Factors that control the rate of staling include time, temperature, moisture level, and the presence of additives such as emulsifiers (crumb softeners). Rate of staling shows a linear response with time, but can be minimized by maintaining the maximum allowable moisture in the product or by storage at warm (room temperature or higher) or cold (below freezing) temperatures. Refrigeration enhances staling since the rate of retrogradation is optimal at cold temperatures just above freezing.
Staling eventually causes a product to become unacceptable at the retail or consumer level. It is estimated that 3-5% of all baked goods produced in the United States are discarded due to a loss in freshness. The value of discarded baked goods has been estimated to exceed $1 billion annually in the U.S. alone. It is obvious that prolonging the freshness of baked goods by retarding staling would be a benefit to the producer, retailer, and consumer.
A common practice within the baking industry to retard staling is to add chemical emulsifiers to the dough formulation. About 12-15 million pounds of distilled monoglyceride and 20-25 million pounds of mono- and diglycerides are used annually in the baking industry for this purpose. However, while chemical emulsifiers do produce a softer bread, they are only partially effective in reducing bread staling because they appear to function by creating softer bread out of the oven rather than by acting upon the mechanism of starch retrogradation directly. That is, the bread still stales at about the same rate, but it starts from a softer loaf and so reaches unacceptable firmness later than untreated bread. As can be surmised from this description, a limiting factor in surfactant use is the initial softness of the loaf: both bakery production processes (such as slicing), and consumer preferences require a certain level of firmness in bread which sets a limit to surfactant use.
In addition to the usage of chemical emulsifiers, enzymes which modify the starch responsible for staling are also used for increasing shelf-life of baked goods. Enzymatic techniques for reducing firming in baked goods have been studied for years, and the beneficial action of enzymes has been recognized. However, commercially available enzymes have been in the past either only marginally effective or they produced offsetting negative effects in product quality that precluded widespread use.
The amylases are a specific type of enzyme which hydrolyze the glycosidic linkages in polyglucans, and for this reason are grouped with hydrolases. The specific amylases of special interest to bakers are alpha-(1,4)-glucan glucanohydrolase (or alpha-amylase) and alpha-(1,4)-glucan maltohydrolase (or beta-amylase) derived from various cereal and microbial sources. The amylases are widely distributed in nature, occurring in many animal tissues, higher plants, molds, yeast and bacteria. Until recently, the only alpha-amylases used in baking were cereal enzymes from barley malt, fungal enzymes derived mainly from
Aspergillus oryzae
, and bacterial enzymes derived from
Bacillus subtilis
. Depending on their origin, alpha-amylases show measurable differences in certain properties, such as pH and temperature optima, thermostability, and resistance to inactivation by acidity. They are simple crystallizable proteins that do not require the presence of coenzymes for their activity. Because of their protein nature, they exhibit a general heat lability. Table 1, shown below, demonstrates the thermostability of alpha-amylases from various sources.
TABLE 1
Temperature
Percent of Enzyme Activity
° C.
° F.
Fungal
Barley Malt
Bacterial
65
149
100
100
100
70
158
52
100
100
75
167
3
58
100
80
176
1
25
92
85
189
—
1
58
90
194
—
—
22
95
203
—
—
8
The data in Table 1 demonstrates that fungal alpha-amylase is quite heat labile and is inactivated rapidly at temperatures above 149° F. (65° C.). A temperature above 167° F. (75° C.) is required for a comparable inactivation of cereal alpha-amylase. Bacterial alpha-amylase is the most stable and shows little loss of activity at temperatures up to 185° F. (85° C.).
As the temperature of the dough rises during baking, starch is gelatinized over the range of 140° to 167° F. (60° to 75° C.), rendering it susceptible to amylase attack. Alpha-amylase specifically hydrolyzes the alpha-(1,4)-glycosidic linkages in starch at random points within the amylose and amylopectin molecules. Some alpha-amylases are capable of hydrolyzing linkages within the amorphous regions of the starch matrix during baking. Under the proper conditions, this limited degree of hydrolysis is sufficient to disrupt the starch network and reduce the rate of staling.
Barley malt is often added directly to wheat flour at the mill to standardize alpha-amylase activity. Standardization enhances production of fermentable sugars from damaged starch, increases yeast growth and gas production, and improves dough handling and proofing. Barley malt also improves finished product properties such as color, grain, texture, and flavor. However, since barley malt retains much of its activity over the temperature range of starch gelatinization, it is important to avoid an excess of cereal amyl
Hendricks Keith
O'Rourke Sarah
Petersen Steven C.
LandOfFree
Methods and compositions for retarding the staling of baked... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Methods and compositions for retarding the staling of baked..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Methods and compositions for retarding the staling of baked... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3174581