An internal standard method for the gas chromatographic head space analysis of the aroma of roast and ground coffee was developed as follows. Five grams of ground coffee was weighed into a 20 ml glass vessel. The vessel was sealed with the silicon rubber septum which hung a filter paper strip (1×2cm). Five μ1 of the internal standard solution (sec-butanol, 3% in benzylalcohol) was injected onto the paper strip with a microcyringe. After equilibration at 30°C for 60 min, 0.1 ml of the head space gas was applied to a gas chromatographic method. 1) The internal standard substance was in adsorption equilibrium when the vessel was incubated at 30°C for 60 min. 2) The relative amount of the aroma based on a relative peak height (sec-butanol=1.00) was little influenced by temperature. 3) A linear relationship existed between the amount of internal standard substance and its peak height. 4) The reproducibilities based on the coefficient of variation ranged from 3.2% (propionaldehyde) to 10.0% (n-hexane) for quantitative analysis of the aroma constituents in the head space gas. 5) The aroma characteristics and the changes of the flavour during storage of ground coffee were studied by comparison of the relative concentration of ten constituents in the headspace gas.

View full abstract

Many saccharides as well as some inorganic salts and organic acids were found to enrich the color density at 520nm of anthocyanin solution (pH3.0) from juice of Campbell Early grapes and to stabilize the enriched color density for forty days at room temperature. (1) All of the sugars tested had hyperchromic effect (enrichment of the absorbance at 520nm). A linear relation was obtained between the enriched absorbance at 520nm(ΔE 520nm) and the sugar concentration (0-2.0M). The trisaccharide had the most hyperchromic effect, followed bydisaccharide, monosaccharide. Thus it was proved that the hyperchromic effect enhanced with increasing molecular weight of sugars. (2) In the case of monosaccharides, the hyperchromic effect (enrichment of absorbance at 520nm) increased in the following order: sugar-alcohols (D-sorbitol and D-mannitol)<ketohexose (D-fructose)<aldopentose (D-xylose)<aldohexoses (D-glucose, Dmannose and D-galactose). (3) Many saccharides effectively maintained the enrichment of absorbance at 520nm during room storage, (4) The stability of anthocyanin pigment in the presence of sugars was markedly influenced by storage temperature: The pigment was favorably held at cold temperature (6°C) and room temperature; the pigment breakdown was accelerated at higher temperature (55°C).

View full abstract

The effects of inorganic salts such as sodium perchlorate and sodium chloride on the spectral and polarographic behaviors of the synthetic pigment (3'-methoxy-4', 7-dihydroxy flavylium chloride) were investigated in the acidic solutions. (1) Addition of sodium perchlorate to the synthetic pigment solutions caused flavylium salt form (absorbance at 468nm; the first wave at -0.35V vs. SCE) to increase and trans-chalcone form (absorbance at 376nm; the second wave at -0.77V vs. SCE)to decrease at a fixed pH (3.0-4.0). (2) The spectral and polarographic behaviors with increasing concentration of sodium perchlorate corresponded to those with decreasing pH. (3) The synthetic pigment solutions resulted in a shift of flavylium salt (colored form)-chalcone (colorless form) equilibrium toward the former form when the inorganic salts were added. (4) These results suggested that the hyperchromic effects (enrichment of E₄₆₈nm) of the inorganic salts on the acidic pigment solutions gave rice to the conversion of chalcone form into flavylium salt form.

View full abstract

The extraction rate of oil from fish muscle with acetone as hydrophilic solvent was investigated to compare with the results of our previous investigation with 1, 2-dichloroethane (EDC) as hydrophobic solvent. The results were as follows. The rate of extraction with acetone was larger than with EDC extremely. In general, the mechanism was thought to be same as that with EDC. These extraction were apparently controlled by "pushing-out" n early stage and by diffusion in later stage. Because of high solubility of water inacetone, however. the simultaneous occurrence of diffusion and "pushing-out" during both stages of the extraction was more frequently than the case with EDC. The effect of temperature on the diffusivity of oil in fish muscle was explained by the well known relation about a homogeneous liquid phase diffusion i.e. D∝T/μ. The difference between the effect of temperature on the diffusivity withaceton and with EDC was explained by the difference of moisture content in fish muscle at different temperatures. The value of diffusivity of oil in acetone was 4.03×16^-6cm²/sec. at 30°C which was smaller than that in fish muscle. This fact was thought to be the effect of "pushing-out" occurred in parallel with the diffusion.

View full abstract

In order to develop one of techniques to extend the use of wheat flour by changing protein contents, visco-elastic behavior of flour fortified with gluten was studied. Soft and hard wheat flours were fortified with gluten to be 13.5-23.0 and 8.4-21.0% of protein contents, respectively. Beside these, soft flour was fortified with hard flour to be 9.4-11.5% of protein contents. Results were as follows. Increasing rate of visco-elasticity with gluten fortification of hard flour dough was less than that of soft flour. Increasing rate of visco-elasticity of soft flour fortified with hard flour was significantlly higher than others at the same protein contents. This fact suggests that only gluten is not the main factor of visco-elasticity but also other components take important part. Mixing characteristics of soft flour fortified with gluten did not show the simillar pattern to that of natural high protein flour.

View full abstract

(1) A method for determination of the hydrophobic region in soybean globulin was established using 1-Anilinonaphthalene-8-sulfonate (ANS) as a probe. (2) In the native and the denatured soybean globulin heated at 90°C in the neutral solution, the maximum amount of ANS bound to 106g of them were 15 moles and 33 moles, and also the relative values of fluorescence intensity occuring by binding them to ANS were 100 and 200, respectively. Thus, the hydrophobic region in the denatured soybean globulin by heat treatment increased to two times of that in the native soybean globulin. (3) It was found that the native protein content decreased with heating the soybean globulin solution, on the other side the hydrophobic region simultaneously increased,

View full abstract

The binding factors of heat denaturation of 11S component or the cold-insoluble fraction (CIF) of soybean protein by heating at 100°C in pH7.6, ionic strength 0.5, were studied. The insoluble aggregate fraction contained more hydrophobic amino acids and hydrophobic region determined with anilinonaphthalene sulfonate than the soluble fraction. When SH blocking agents such as N-ethylmaleimide or p-chloromercuribenzoic acid were added to CIF, the insoluble aggregates did not occured but the soluble aggregates which contained more hydrophobic amino acids and hydrophobic region were formed, The precipitation was not easy to be formed under the oxidative condition of SH group. From these results, it is presumed that by heating at 100°C, a part of subunits of 11S or CIF changed into the soluble aggregates by hydrophobic interaction and subsequently to the insoluble aggregates through the reaction of intermolecular disulfide bonds.

View full abstract

The keeping quality of milled rice packaged under vacuum or gas including nitrogen, carbon dioxide and air was investigated during storage at 30°C for 3 months. The amount of reducing sugar and fat acidity of the milled rice did not show significant difference among the tested samples including less than 14.7% of moisture. Sensory evaluation on the taste also gave the same tendency except that the sample packaged in air was slightly low in the score. When the moisture content of the rice was above 15.7%, vacuum package gave the best keeping quality followed by gas package and air package in this order.

View full abstract