We examined the relationship between the starch content of potato and its cooking quality. Potato tubers were assigned according to their starch content from 12% to 16%. They were cooked by different methods and a sensory evaluation then carried out. In the case of boiling, steaming, frying and heating in a microwave oven, potato with the high starch content (HS) was evaluated as having a richer and more mealy feeling and better taste than potato with the low starch content (LS). On the other hand, in curry and nikujaga (pototo stewed with pork), LS was evaluated to be better than HS because of less collapse after cooking. In potato salad, HS was evaluated more highly than LS in taste only by the manufacturers' panel. The glutamic acid content was particularly low in potato tubers with a starch content of 15% and above.
Sweet potato slices were cooked for 5 min in distilled water, alum (aluminum potassium sulfate), AlCl3, NaCl and buffer solutions at several pH levels. Slices preheated (60°C)or pressurized(686MPa) were also boiled in water. The slices cooked at pH3∼pH4 were firmest among those in the range pH2∼pH12. When slices were cooked in various solutions at the same pH level (pH3.3), firmness was (greatest to least); cooked in alum buffer≥buffer>AlCl3>alum solutions. Firmness was (greatest to least); preheated>raw>ressurized>preheated then cooked>pressurized then cooked>cooked in alum solution>cooked in water>cooked in NaCl solution. A clear relationship was found between firmness and the amount of pectin remaining in tissues except slices cooked in alum solution. Scanning electron microscopy showed the middle lamella separated when cooked in water, NaCl, or buffer solutions of pH2 and pH8, but not when cooked in water after preheating or pressurization, in buffer solution (pH4), or solutions with aluminum ion. Starch grains were not swollen even after preheating for 2h at 60°C, but when pressurized for 1h at 686MPa, they were swollen and half-gelled. Acid, preheating, pressurization and Al3+ prevented softening of slices.
Dried sea cucumber is used in both Japanese and Chinese dishes after being soaked in water, and its characteristic texture is appreciated. Successive in soaking water, boiling and cooling of the dried material is the most common restoring method, but the weight ratio and texture of the restored sea cucumber varies according to the test sample. To investigate why this happens, we investigated the components of dried sea cucumber before and after being soaked in water. It was found that the sea cucumber after soaking was higher in weight ratio and more tender in texture with increasing collagen and glucosaminoglycan contents of the dried material. This result was confirmed by scanning electron micrography, whereby the dried sample containing more collagen and glucosaminoglycan, after being soaked in water, was better able to expand its network structure and retain more water.
Ascorbate oxidase (AAO, EC 126.96.36.199. ) is widely distributed in plants and is responsible for the oxidation of ascorbate during the storage and processing of vegetables. We found two AAO isozymes in the sprouts of Vigna mungo. The main isozyme was separated by DE-52 cellulose column chromatography and purified by Sephacryl S-200 gel filtration. The molecular mass of the isozyme II was 125kDa by Sephacryl S-200 gel filtration. The optimum pH value was 4.50, and the Km value for ascorbic acid was 4.50×10-5M. The enzyme activity was inhibited by various salts in the order of sodium citrate>NaCl>KCl>sodium malate>NH4Cl>(NH4)2SO4. Sodium citrate and NaCl inhibited the enzyme activity competitively with respective Ki values of 25mM and 28mM.
The optimum punching of dough by the straight dough baking method was studied. The time interval between mixing the dough and the first punching was defined by the new method of measuring the straight dough expansion. The standard time to the first punching was 50 minutes, and from the first to the second punching was 40 minutes. Two types of punching schedule were selected for comparison with the standard punching schedule. One used the time to the first punching of 25 minutes (half the standard time) and to the second punching of 65 minutes. The other schedule used no punching before panning. Both the dough and cooked bread on the standard punching schedule had the highest hardness. According to the results of a sensory evaluation, the bread prepared by the straight dough baking method with the first punching schedule was more favored than that with the second schedule without punching.
A survey on contemporary daily cooking in France was carried out in Strasbourg (Alsace) to better understand the current diet in France and the constituents used in daily dishes. The results were obtained from 121 French women ranging in age from the 20 s to 60 s. About 70% of the subjects ate bread at breakfast, mostly with both butter and jam. Some ate cereals, biscuits or cakes for breakfast, while coffee was drunk by most of them, and tea by some. Fruit, egg dishes, ham and dairy products were eaten by some subjects, although not very often. Beef, pork and other types of meat were eaten at lunch, almost always accompanied by cooked potatoes. Salad, fruit and dessert were frequently eaten at lunch and dinner, while soup and cheese were more often served at dinner than at lunch. Instead of beef and pork dishes, sausages and ham were usually served at dinner. The average number of dishes was three to four both lunch and dinner. In addition, the number of dishes served at lunch was more than that served at dinner.
The effect of the method used for hand-making tofu on the taste and mineral contents was studied. The mineral contents of soybean milk increased with increasing heating temperature of “go” (mashed and boiled soybean). Tofu solidified at a high temperature resulted in a little water separation. When the temperature was 100°C, the contents of such minerals as Na and K in tofu were higher then when a lower temperature was used. The contents of Zn, Mn, Fe and Na in the soybean milk were higher with a mixing time of three minutes than with five minutes. Moreover, the contents of Fe, Na and Ca were higher with a coagulation temperature of 75°C than with 85°C. A significant difference in the flavor and total evaluation of taste depending on the coagulation temperature was also recognized.