We had showed that the impulse waveform of acoustic signals induced by impact to a muskmelon was transmitted along the surface of equator with uniform velocity. This velocity varies according to melon maturity. This paper deals with the development of the system for determining transmission velocity. The system consists of 2 microphones, an A/D converter with the simultaneous sample-and-hold circuit and a computer. Calculation of the lag time from the two microphone signals using cross-correlation techniques was very repeatable. Transmission velocity was determined by dividing the distance between the microphones by the lag time. Experimental results were as follows: (1) The microphones should be located on the equator 45°-90°from impac point. (2) Optimum microphone-to-sample distance was found to be 1-4mm. (3) For an A/D conversion rate of 100kHz, a minimum of 512 data points were needed to calculate the accurate lag time by cross-correlation techniques. (4) Edible muskmelons varied in hardness from 250 to 700gf (3mm plunger method). (5) Correlation coefficient between transmission velocities and fruit hardness was found to be 0.832. The transmission velocity of edible muskmelons was ranged from 37 to 50m/s.

View full abstract

The textural structure of hand-streched and machine-made noodles was precisely observed by scanning electron microscope(SEM) after α-amylase treatment to eliminate interfering starch granules. The gluten structure in the dry noodle was clearly exposed by the α-amylase treatment. In the dry hand-streched noodle, SEM revealed the characteristic fibrous gluten structure along by the streching direction, and starch granules retained in fibrous gluten. On the other hand, random structure was observed in the dry machine-made noodles. The cooked noodles were similarly observed by SEM. The characteristic structure observed in the dry hand-streched noodles was well retained even after cooking, although gluten slightly swelled.

View full abstract

Volatile flavor compounds were collected by lyophilization from fresh and heated juices of Satsuma mandarin and three cultivars of sweet orange, and then analyzed by using GC and GC-MS. β-Terpineol (cis) and, β-damascenone, which was found in the heated Satsuma mandarin juice, could not be identified in the sweet orange juices. d-Limonene, linalool, octanal and ethyl butyrate decreased and α-terpineol increased by heating. On the other hand, changes of these compounds obtained from the sweet orange juices were smaller than those in Satsuma mandarin juice by heating.

View full abstract

Effects of heat treatment and enrichment of vegetable fat on the fermentation of soymilks by lactic acid bacteria and bifidobacteria were examined. The marked acid development was observed in soymilks fermented by bifidobacteria compared with those by lactic acid bacteria. The heat treatment of soymilk at the temperatures higher than 100°C decreased titratable acidity, and increased hardness of the curd in the fermented soymilk with Bifidobacterium longum. Enrichment of vegetable fat to the soymilk did not affect the acidity and texture of the fermented soymilk. However, homogenization of the soymilk with high pressure lowered hardness of the curd.

View full abstract

The presence of a yellow pigment containing a β-carboline derived from 1- (2'-pyrroli-dinethion-3'-yl) -1, 2, 3, 4-tetrahydro-β-carboline-3-carboxylic acid (PTCC) was investigated in salted radish roots. PTCC spotted onto silica gel plates was allowed to stand for five days at 40°C, resulting in the generation of yellow pigments. The methanol extract was subjected to Toyopearl HW-40 S column chromatography using methanol as an eluent. The major peak was concentrated to give a yellow powder. The UV, IR and NMR spectra showed that the yellow compound had a β-carboline moiety derived from PTCC by its decarboxylation. On the other hand, yellow pigments extracted from salted radish roots were fractionated on a Sephadex LH-20 column using 50% methanol as an eluent. Among three fractions, the main yellow fraction was isolated and analyzed by paper chromatography, UV and IR spectroscopy. These data showed that the yellow pigment was similar to those of yellow pigment derived from PTCC. Thus, it was confirmed that PTCC contributed to the development of abright yellow pigment in salted radish roots. Effect of light resistance on the pigment was similar to that of curcumin. However, the color of the pigment was slightly turned to a brown with 1 mM ferrous ion. Also, the pigment exhibited no mutagenic activity to S. typhimurium TA 98 and TA 100 with and with out S-9 mixture.

View full abstract

The nutritional requirement for the vegetative growth of Agrocybe cylindracea (Fr.) Maire (yanagimatsutake mushroom) was investigated by synthetic liquid medium. (1) A wide range of carbohydrates was utilized as carbon sources in the medium which supported growth of Agrocybe cylindracea. Glucose, xylose, mannose, fructose, lactose, maltose, dextrin, glycogen, pectin and soluble starch were especially good carbon source for mycelial growth. However, rhamnose, sorbose, sucrose, erythritol, arabitol, xylitol, mannitol, galactitol, inositol and adonitol were not effective as carbon source. (2) Yeast extract, soyton, peptone, meat extract, Casamino acid and the amino acids mixture of the basal medium were acceptable nitrogen sources for the growth. On the other hand, ammonium and nitrate salt were poor as nitrogen source for vegetative growth. (3) The vegetative mycelium did not grow in the absence of KH₂PO₄ and MgSO₄. The vegetative mycelium yield was severely decreased by the omission of ZnSO₄. The other mineral salts [CaCl₂, FeSO₄, CuSO₄, MnSO₄, (NH4)₆ Mo₇O₂₄] did not show any special effect for the vegetative growth. (4) The vegetative mycelium required thiamine for the growth. Each of the other vitamins (nicotinamide, riboflavin, pantothenic acid, pyridoxine, folic acid, cyanocobalamin, biotin, inositol) was effective for the vegetative growth. (5) Nucleic acid bases (adenine, guanine, cytosine, thymine, uracil, orotic acid) was effective for the vegetative growth.

View full abstract

Effect of α-tocopherol, lecithin, and. menadione on chlorophyllase from goosefoot was investigated. The concentration of additives in a reaction mixture was 10 and 20mM. α-Tocophopherol which had phytyl side chain showed little effect on chlorophyllase activity. Lecithin which was an ampholytic surfactant accelerated the enzyme activity. Activity of the enzyme with lecithin was twice as much as that without lecithin. Menadione which took part in the oxidation reduction reaction in vivo inhibited the enzyme activity at a high concentration. However, it accelerated the enzyme activity at a low concentration.

View full abstract

Amylography, an important medium for evaluating eating quality, has such faults that is expensive machine, a sample size and measuring time. Gel consistency is often determined instead of amylography as a simplified method, by IRRI and other laboratories. In this study, gel consistency and amylography were measured on twelve samples. Modification on the standard method was required for determining gel consistency of "New characteristic rices" which have the novel characters as the Japonica rices. From the fact that the gel consistency showed high correlation to the amylography, the correlation of gel consistency to eating quality was suggested. Good eating quality of Sasanishiki from its large gel consistency, and poor eating quality of Hoshiyutaka from its small gel consistency were predicted.

View full abstract

Recent studies revealed that kiwifruit does not evolve no ethylene virtually and not ripen without any help of some exogenous factors. In order to know how to improve commercial ripening of kiwifruit, the fruits purchased from retail shops were studied on ripening, ethylene production, occurrence of soft rot and fruit quality.
1. Domestic kiwifruits hardly evolved ethylene even 10 days after purchase, except soft rotted fruit which comprised about 40% of the total fruit.
2. The greater part of kiwifruit imported from New Zealand also did not evolve ethylene 10 days after purchase. Four percent of the fruit, however, evolved ethylene with occurence of soft rot and 14% of the one did without soft rot. The ones purchased from wholesales did not produce ethylene and ripen with a few exception.
3. Ethylene of zero to over 50ppm was detected in small plastic boxes in which kiwifruits were enclosed for retail. Ethylene of 0.5 to 5ppm accumulated in the box enclosing one ethylene producing and 4 non-producing fruits.
4. Only about 40% of the purchased kiwifruit became eatable through 10 days after purchase in terms of flesh firmness and acid contents even though soft rot fruit was taken into account.
These results suggest that it is necessary to make up a system to ship and retail kiwifruit compulsorily ripened by exogenous ethylene.

View full abstract

Optimum conditions for fermenting an Alaska pollack frozen surimi to a new kind of kamaboko by using Lactobacillus casei-12, Lactobacillus plantarum-47-3 or Lactobacillus plantarum-4 (ST) as each starter were examined. Viable counts of lactic acid bacteria, pH, breaking force and breaking strain in fermenting kamaboko were measured. After addition of 2.5×10⁸/g of Lactobacillus casei-12 and 0.5% (W/W) corn steep liquor with another additive to surimi, the incubation at 30°C for 30h caused optimal fermentation. The characteristics of the kamaboko were as followes; pH, 4.5, breaking force, 1791g, breaking strain, 8.9mm and viable count for lactic acid bacteria, 1.3×10⁹cells/g. Solidification of the kamaboko occurred not only through setting process but also through the diffusion of acid to protein. The kamaboko has a sour taste and differs from the kamaboko available on a market.

View full abstract

The expansion potential of cake batter was tested under reduced pressure conditions. When sponge cake batter with wheat flour or wheat starch was prepared (at 25°C), the expansion of air cells through incremental increase in internal pressure was greater in wheat starch batter than in wheat flour batter. When the sponge cake batters were heated in the oven to 60°C, 70°C, or 80°C, the expansion of air cells was inhibited by the heat denaturation of ingredents more remarkably in wheat flour batter than in wheat starch batter. As a result, the expansion behavior of the wheat starch cake batter was found to be considerably higher, more stable and continuous, compared with that of the wheat flour cake batter.

View full abstract

The addition of the condensate obtained by the steaming of roasted and ground coffee to coffee extract enabled us to produce a soluble freeze-dried coffee having the characteristics of a regular brewed coffee. This is difficult to achieve using conventional soluble coffee production methods. Under optimum condition of steam flow rate, a "Floral" note, typical of regular brewed Colombian, was imparted to the soluble coffee product.
The total amount of acids in the steam condensate and the steamed coffee was larger than that in the extract from a non-steamed coffee control. This suggests that the steaming process generates acids because coffee is exposed to high temperatures during steaming. Organoleptic evaluation also confirmed stronger sourness in soluble products made from steamed coffees with aroma added back than that from non-steamed coffees.

View full abstract

Volatile aroma compounds and acids were recovered in a short time period from roasted and ground coffee by steaming in a continuous counter-current apparatus. It was found that the recovery of volatiles depended upon the temperature of coffee steamed rather than the residence time of the coffee in the equipment. The total acid recovered both in the aroma condensate and in the aqueous extract from the steamed coffee with 5 minutes residence time was almost the same as that in a non-steamed coffee control. The generation of excess acids during steaming could therefore be minimized by short steaming times, compared with the traditional method of steaming a static coffee bed in a percolation column.
As steam flow rate was increased to obtain more condensate, the amount of total organic volatile compounds recovered in the condensate did not increase proportionally. Recovery of sulfur-containing compounds, however, significantly increased with the increase of steam flow rate.
Organoleptic evaluation of the coffee to which steam aroma was added suggested that sulfur-containing compounds were a key facter in obtaining regular brewed coffee flavor in a cup of soluble coffee.
The flavor of the steamed coffee deteriorated rapidly upon discharge from the equipment to the atmosphere. By organoleptic evaluation, a significant deteriorated note was perceived in the extract prepared from steamed coffee after 30 minutes hold-up. Acid generation in the steamed coffee increased rapidly after 90 minutes hold-up.

View full abstract

A controlled coagulation system applying torque measurement was developed in order to investigate the related factors. From the characteristic rise of torque curve, proper amounts of coagulant could be determined automatically. The coagulated soymilk reacted with steadily added calcium chloride by this system, molded to intermediate "tofu" and then frozen and dried to final product "kori tofu". The optimum coagulation conditions were precisely examined at the various reaction conditions of concentration of soymilk, reaction temperature, and concentration of coagulant. The relationships between the torque changes and the properties of tofu and kori-tofu were also investigated.
Through a series of coagulation and pressing experiments with this new system, following results were obtained. (1) Determination of the required amount of coagulant as well as the on-off control of stirring of soymilk are performed automatically. (2) The optimum initial concentration of soymilk was around 5% from the view point of water holding capacity of the dried kori-tofu. (3) The higher temperature, between 54 and 70°C, shortened the pressing time, hardened the tofu curd in one hand and decreased the water holding capacity of kori-tofu in the other. The optimum temperature was 60 to 65°C. (4) The optimum concentration of calcium chloride was around 10mM in the present experimental conditions.
These findings contributed to the semi-automated processing and the products of fine properties.

View full abstract