the process of the present invention will be further illustrated with reference to the drawings . with reference to fig1 and 4 , a viscoelastic material 2 is passed through a gap between a pair of rollers 1 , 1 or a pair of endless belts 1 , 1 and torn or scraped off the surfaces of the rollers 1 , 1 or endless belts 1 , 1 by a pair of scrapers 3 , 3 to form a board or sheet - like material . the structures of viscoelastic material in cross section are shown in fig2 and 3 . from the above explanation , it is obvious to those skilled in the art that any strict controls or regulations for the process , physically or chemically , are not needed and any troublesome additives are not needed for the production of the structure according to the present invention . thus , superior quality of an expanded board or sheet - like product can be quite easily obtained without any strict control of the ingredients or physical conditions . for example , any starch containing material like rice , wheat , corn or other cereals , potatoes , etc . can be applied to the process of the present invention . that is , the viscoelastic material of the present invention can be easily prepared from the starches contained in the above materials by a conventional gelatinizing process like water addition , heating , etc . by means of , for example , heat exchanging double oven , direct steam injection or hot water addition . gelatinizing of starches under heating is effected , preferably with starches containing 35 % by weight or more of water , and heating is not always necessary for gluten - containing material like wheat or gluten added materials . the invention will be further illustrated but is not limited by the following examples . after adding water to adjust the water content to 46 %, 10 kg of non - glutinous steamed rice flour of 300 mesh in particle size was again steamed under the pressure of 0 . 25 kg / cm 2 for 8 minutes in a steam kneader , and then sufficiently kneaded in a kneader to obtain a dough cake . the dough cake was passed through a gap of 0 . 3 mm between a pair of rotating rollers and subsequently a gap of 9 mm between a pair of scrapers . the rolled dough cake was torn off the surfaces of the rollers by the scrapers to form a board or sheet - like structure expanded in thickness , having a plurality of enlongated rectangular perforations or chambers in cross section . the rectangular perforations were 2 . 2 mm in length and 2 . 6 mm in width . in the same manner , the process of the invention was carried out by setting the gap between a pair of rotating rollers at 0 . 6 mm and 0 . 9 mm , respectively , to obtain an expanded board structure with a plurality of elongated rectangular perforations or chambers in cross section . the rectangular perforations were respectively 3 mm × 3 . 7 mm and 3 . 8 mm × 4 . 3 mm . the board structure obtained was cut into desired pieces , dried to adjust the water content to about 13 % and baked to give non - glutinous wafer - like rice crackers with such a structure as shown above . the rice crackers were very excellent and refined in both appearance and taste , as compared with so - called rice crackers produced in the prior art . 1 kg of wheat flour , 200 g of sugar , 200 g of butter , 2 g of sodium bicarbonate , 2 g of ammonium carbonate and 230 g of hot water at 90 ° c was sufficiently mixed and kneaded in a mixer to obtain a viscoelastic dough cake . the dough cake was passed through the gap of 0 . 9 mm between a pair of rotating rollers , and then the gap of 9 mm between a pair of scrapers . the rolled cake was thus torn off the surface of the rollers to form an expanded board or sheet - like structure with a plurality of elongated spaced rectangular perforations or chambers in cross section . water was added to corn starch and homogeneously mixed up to 50 % of the water content . the mixture was heated under the pressure of 0 . 5 kg / cm 2 for 12 minutes in an autoclave to obtain a gelatinized dough cake , which was further kneaded sufficiently . this viscoelastic dough cake was passed through a pair of rotating rollers and torn off the surfaces of the rollers by a pair of scrapers to form an expanded board or sheet - like structure . the gaps between the pair of rollers and between the pair of scrapers were 0 . 3 mm and 9 mm , respectively . the expanded board or sheet - like structure had a plurality of elongated rectangular perforations or chambers which were 2 . 4 mm in length and 2 . 5 mm in width in cross section . the expanded board was dried to 16 % of water content , thereby obtaining a semitransparent expanded board . in the cross section of the semitransparent expanded board , the wall thickness of the surface and back sheets , and the inner bulkheads were 0 . 25 mm and 0 . 5 mm , respectively . the rectangular perforations were 2 . 0 mm in length and 1 . 9 mm in width . 5 parts by weight of water was added to a mixture comprising 7 parts by weight of potato flakes and 3 parts by weight of waxy corn starch and then mixed sufficiently in a mixer . this homogeneous mixture was kneaded with steam under the pressure of 0 . 2 kg / cm 2 for 8 minutes to give a dough cake . the dough cake was passed through between a pair of rotating rollers having a gap of 0 . 2 mm , and then between a pair of scrapers having a gap of 7 . 5 mm . the rolled dough cake was torn off the surfaces of the rollers by the scrapers to form an expanded board or sheet - like structure having a plurality of enlongated spaced rectangular perforation chambers in cross section . in cross section , the rectangular perforations were 2 . 0 mm in length and 2 . 2 mm in width . the expanded board was then cut into desired pieces , and dried at 60 ° c in a drier , whereby the water content was adjusted to about 10 %. the dried pieces were fried in an oil bath at 150 ° c to give tasty food like potato chips having rectangular perforations in cross section . as is understood from the above explained examples , a novel refined expanded wafer - like food product , that is quite different from those known in the prior art , is easily obtained according to the present invention , without employing any expensive machine or any special ingredients . further , the food product of the present invention is quite excellent and refined in appearance and taste . the invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof . the present embodiments are therefore to be considered in all respects as illustrative and not restrictive , the scope of the invention being indicated by the appended claims rather than by the foregoing description , and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein .
an expanded board - like food product in the form of a thin wafer - like sheet having a plurality of elongated chambers rectangular in cross section and formed by passing a viscoelastic dough cake formed of edible vegetable material through a gap between a pair of opposingly rotating rollers and then a gap between a pair of scrapers . the product has many advantages to the conventional plastic porous board .