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
1999-12-03
2002-08-20
Paden, Carolyn (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,...
C426S112000
Reexamination Certificate
active
06436462
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a boiled rice food capable of being distributed and sold at low temperatures. In the concrete, this invention relates to a boiled rice food prepared from boiled rice which is less likely to become hard and remains glutinous during storage at low temperatures or after thawing after freezing.
In this invention, “distribution at low temperatures” means distribution within temperature zone below 10° C. where non-frozen food or thawed frozen food is kept unfrozen, and “sale at low temperatures” applies to the period till the time when the consumer eats the food. “Heating” means elevation of the food temperature to 50° C. or higher, where starch is re-gelatinized, by heating in a microwave oven, in hot water, etc.
BACKGROUND OF THE INVENTION
Boiled rice becomes harder with time. This phenomenon is called staling of boiled rice and the change is greater at low temperatures. Staling is the change of starch with time which is said to be caused by recrystallization of gelatinized starch by the action of water and heat. Staling of boiled rice is controlled by addition of an enzyme (&agr;-amylase, &bgr;-amylase, glucoamylase, protease, etc.), starch (gelatinized starch, processed starch, etc.), polysaccharide (Gellan gum, hyaluronic acid, etc.), sugar (anhydro sugar, dextrin, glucose, fructosle, cyclodextrin), sugar alcohol (trehalose, multitol, sorbitol, lactitol, etc.), emulsifier (sucrose fatty acid ester, polyglycerol fatty acid ester, organic acid monoglyceride), etc. Although: each of these substances is effective to some extent, staling of boiled rice cannot be prevented completely with this technique alone. For example, plain boiled rice, when stored at 5° C. for 24 hours with one of them or some of them in combination, is hard and difficult to be eaten as it is.
For the reason described above, boiled rice which has once been stored at low temperatures requires heating in a microwave oven or by other means before eating. In a chilled lunch and prepared dish shop, for example, boiled r:ice is generally distributed and sold at 15° C. or above where staling of boiled rice is less likely in case of eating without heating. Thus distribution and sale at 15° C. or above may suppress staling of boiled rice, but in this zone of temperature, growth of bacteria is problematic which requires use of a antimicrobial agent.
Moreover, staling of starch is an obstacle to thawing of a frozen boiled rice food without heating, which is particularly evident in thawing at low temperatures without heating. In this case, the food deteriorates and the surface of boiled rice is whitened, i.e. the surface becomes wax-like. These phenomena are noted also at temperatures over 0° C. but, as described above, particularly evident after thawing of frozen boiled rice food at low temperatures. For example, rice boiled with increased amount of water is eatable for a longer time when stored unfrozen at low temperatures. However, when boiled rice has once been frozen and then thawed at low temperatures, deterioration of texture is slightly prevented by increased water, but wax-like appearance is rather more marked. Thus deterioration of a boiled rice food is more marked after gradual thawing of frozen boiled rice food than after storage of unfrozen food at low temperatures. That is, texture deteriorates and wax-like appearance appears more rapidly in the thawing temperature zone below 0° C., particularly in the range from −5° C. to 0° C. Therefore for thawing of frozen boiled rice food, it is necessary to pass the temperature zone ranging from −5° C. to 0° C. rapidly by thawing with heating in a microwave oven or in hot water, or by spontaneous thawing at ordinary or higher temperatures. For this reason there is no frozen boiled rice article that can be thawed at low temperatures, and frozen boiled rice is not distributed or sold at low temperatures.
Moreover, the extent of staling is different among types of boiled rice foods. For example, sushi is far less liable to stale than rice ball; frozen sushi articles are available which are eaten after thawing at ordinary or higher temperatures, while there are no frozen rice ball articles that do not require heating in a microwave oven before eating. Chilled sushi articles distributed at 7 to 10° C. are available, whereas there are no other boiled rice articles that are distributed at low temperatures, particularly at chilled temperatures below 5° C. where bacteria grows scarcely and no antimicrobial agent is required. Namely it is desirable that chilled sushi now distributed at 7 to 10° C. is distributed at lower temperatures for the fish materials to be kept as fresh as possible, but the technique for distribution of boiled rice at 5° C. has not been established yet. Sushi is less liable to stale because seasonings such as sugar make sushi slightly resistant to staling and because eating boiled rice together with fish materials obscures the texture of boiled rice.
Glutinous rice, having properties genetically different from those of non-glutinous rice, is known to be resistant to staling. However glutinous rice is not suitable for above-mentioned prepared dish because of its peculiar odor and the undesirable texture due to excessive glutinousness.
DISCLOSURE OF THE INVENTION
The purpose of this invention is to provide a boiled rice food which is less liable to become hard even after storage at low temperatures or after thawing after freezing, and prepared from polished rice having a phosphorus content of not less than 1,200 ppm, which is preferably non-glutinous rice having an amylose content of not more than 15%. The purpose of this invention is to provide a boiled rice food distributed at low temperatures or a frozen boiled rice food which is eatable without heating.
The inventors have found that a low-amylose rice having a phosphorus content of not less than 1,200 ppm and an amylose content of not more than 15% is resistant to staling, and that such rice is suitable for distribution and sale at low temperatures. This invention has been made based on this finding.
The gist of this invention is a boiled rice food that can be distributed and sold at low temperatures characterized in that a polished rice having a phosphorus content of not less than 1,200 ppm, preferably not less than 1,300 ppm, most preferably not less than 1,400 ppm has been selected as the starting rice material, preferably a frozen-chilled boiled rice food which can be eaten without heating, and most preferably sushi. The starting material rice of this invention is :a non-glutinous rice, preferably a non-glutinous rice having an amylose content of not more than 15%, most preferably a non-glutinous rice having an amylose content of not more than 12%, selected from those belonging to varieties of Ouu No.344, 343, or 354. The boiled rice food of this invention that can be distributed and sold at low temperatures is a boiled rice food that can be distributed and sold at low temperatures of 15° C. or below, preferably temperatures as low as 10° C. or below, still more preferably temperatures of 5° C. or below. The boiled rice food of this invention that can be distributed and sold at low temperatures is prepared from al boiled rice prepared by boiling with a salt such as Ca salt as a food additive, and such salt is added by boiling with salt-concentrated water or salt-added water, and is characterized in that no: antimicrobial agent is needed because the food can be distributed at low temperatures. The frozen boiled rice food is characterized in that such food is prepared by block freezing or by compressed molding or by in vacuo packaging.
“Phosphorus content” in this invention is based on the value obtained by colorimetry where rice polished to 90% (Attention should be paid to the degree of polishing in measurement of phosphorus content because phosphorus in rice is rich in the aleuron layer.) is hydrolyzed with sulfuric acid followed by determination using vanado-molybdophosphoric acid, and expressed as the content in dried material. Phosphorus
Koriyama Tsuyoshi
Takami Kouji
Armstrong Westerman & Hattori, LLP
Nippon Suisan Kaisha Ltd.
Paden Carolyn
LandOfFree
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