Food or edible material: processes – compositions – and products – Products per se – or processes of preparing or treating... – Plant material is basic ingredient other than extract,...
Reexamination Certificate
1999-12-15
2001-11-13
Pratt, Helen (Department: 1761)
Food or edible material: processes, compositions, and products
Products per se, or processes of preparing or treating...
Plant material is basic ingredient other than extract,...
C426S573000, C426S634000, C426S639000
Reexamination Certificate
active
06316042
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to boiled rice foods capable of being distributed at low temperatures. Specifically, the present invention relates to boiled rice foods having a texture which does not deteriorate following distribution and storage at low temperatures, and which are free from hygienic problems associated with warming or thawing at room temperature.
More specifically, the present invention relates to boiled rice foods having a texture which does not deteriorate when warmed or thawed following chilled or frozen distribution, and which are free from any hygienic problems associated with warming or thawing at room temperature. In the present invention, “chilled distribution” refers to distribution and storage in a temperature below about 5° C. and above a freezing point; “frozen distribution” refers to distribution and storage in a temperature range which enables freezing; while “de-chilling” refers to warming in a temperature below about 10° C. and above a freezing point.
Cooked boiled rice hardens over time. This phenomenon is also called deterioration of boiled rice. The degree of deterioration increases at lower temperatures. Such deterioration results from changes in intrinsic starch and it has been suggested that the mechanism involves recrystallization of starch which has been gelatinized and swollen under the influence of water and heat. In particular, the taste, texture and flavor of boiled rice all significantly deteriorate after distribution and storage at a temperatures sufficiently low to cause chilling or freezing.
In order to prevent the deterioration of boiled rice, attempts have been made which utilize methods such as increasing the amount of water added for cooking or adding enzymes such as &agr;-amylase, &bgr;-amylase, glucoamylase and protease, starch such as pregelatinized starch and chemically modified starch, polysaccharides such as Duran gum and hyaluronic acid, sugars such as anhydrosugar, dextrin, glucose, fructose and cyclodextrin, sugar alcohols such as trehalose, maltitol, sorbitol and lactitol, or fatty acid esters such as sucrose fatty acid ester, polyglycerin fatty acid ester and glycerin fatty acid ester, and emulsifiers such as organic acid esters of monoglycerides. However, none of these methods achieve any significant improvement in taste or texture.
When boiled rice foods containing these additives are chilled or frozen for distribution, various methods are available to effect de-chilling or thawing, such as allowing the food to stand at room temperature for a period of time, warming at a relatively low temperature (de-chilling), or thawing by heating in a microwave oven. However, if foods are left to stand at room temperature for a period of time, a hygienic problem can arise. In addition, thawing by heating is not suitable for boiled rice foods such as sushi. If the microwave method is used for more suitable foods, hardening is likely to result, causing an undesirable taste, texture and flavor. The same problem exists with respect to de-chilling. When boiled rice foods produced in a conventional method are subjected to de-chilling, such foods will suffer a deterioration in taste and texture.
As a countermeasure against such deterioration, a method of adding trehalose or trehalose plus sugar alcohol (e.g. JP-A 8-168350 and JP-A 9-163943) has been proposed. This method is said to enable foods to be returned to an edible state without heating following chilled or frozen storage and distribution. However, no improvement in taste and texture can be achieved using de-chilling, thus such foods should be thawed at room temperature. Thus, the problem of hygiene is not solved thereby. Further, thawing at room temperature does not effect a satisfactory improvement in taste and texture.
The object of the present invention is to provide boiled rice foods the taste, texture and flavor of which do not deteriorate when returned to an edible state by hygienic de-chilling after being distributed in a chilled or frozen state.
SUMMARY OF THE INVENTION
As a result of intensive study to solve the object described above, the present inventor has found that by adding soybean polysaccharides and trehalose during cooking, deterioration in the quality of boiled rice foods with respect to taste, texture and flavor, caused by chilled distribution or frozen distribution, can be prevented to a far greater extent than that achieved by the conventional method. It has also been found that, as a method of returning boiled rice foods to an edible state, this technique can be applied to de-chilling or thawing at relatively low temperatures thus avoiding hygiene problems which arise at room temperature.
The present invention provides boiled rice foods containing soybean polysaccharides and trehalose. The boiled rice foods of the present invention can be obtained by cooking rice with addition of soybean polysaccharides and trehalose. The boiled rice foods of the present invention containing soybean polysaccharides and trehalose are advantageous in that deterioration in the quality of the rice foods with respect to taste and texture can be prevented when they are de-chilled following chilled or frozen distribution. Further, hygienic problem caused by thawing at room temperature can be avoided. Thus, the boiled rice foods of the invention are much more suitable for low-temperature storage and distribution than the conventional products.
DETAILED DESCRIPTION OF THE INVENTION
As used herein, the term “soybean polysaccharides” refers to water-soluble polysaccharides, such as hemicellulose. Preferably, SOYAFIBE-S™ (Fuji Oil Co., Ltd.) may be used as a soybean polysaccharide. The soybean polysaccharides are added in an amount of 0.1 to 4% by weight, and trehalose is added in an amount of 0.1 to 4% by weight, preferably 0.5 to 3% by weight, more preferably 1 to 2.5% by weight, relative to the amount of raw rice. Soybean polysaccharides are believed to contribute to an increase of water absorbed in boiled rice, and trehalose is believed to have the effect of fixing water absorbed in boiled rice. It is currently believed that, by addition of these compounds, the amount of water absorbed in boiled rice is significantly increased and fixed therein, whereby a sufficient amount of absorbed water remains in boiled rice even upon de-chilling or thawing following chilled or frozen distribution, thus deterioration In taste, texture, flavor can be prevented.
In a preferred embodiment of the present invention, the improvement in taste, texture and flavor becomes even more pronounced when a food-grade enzyme is added. Selection of a suitable food-grade enzyme is not particularly limited so far as it can be used in boiled rice foods, and examples include &agr;-amylase, &bgr;-amylase, glucoamylase, pectinase, protease or papain. A wide variety of food-grade enzyme preparations containing a mixture of enzymes such as amylase, protease and papain are commercially available. For example, an enzyme preparation Miora™ (Otsuka Pharmaceutical Co., Ltd.) is suitable for use. These food-grade enzymes are added in an amount of 0.0001 to 1% by weight, preferably 0.0002 to 0.5% by weight, more preferably 0.0005 to 0.1% by weight relative to the amount of raw rice. It is believed that these food-grade enzymes facilitate the hydrolysis of cell walls, cell membranes and amyloplast membranes of rice albumen or starch particle-binding protein to promote gelatinization and swelling of starch particles, thus contributing to an increase in the amount of water incorporated into the cooked rice.
In accordance with the invention, the boiled rice foods containing soybean polysaccharides and trehalose exhibit a reduced deterioration in their texture. In addition, the amount of water incorporated is increased by adding a food-grade enzyme to improve water retention efficacy, thereby further improving taste, texture and flavor.
In another preferred embodiment, the boiled rice foods of the present invention may further contain edible acetic acid and edible fats and oils. Edible acetic acid
Birch & Stewart Kolasch & Birch, LLP
Iwamoto Tadahiro
Pratt Helen
LandOfFree
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