Flavor descriptive terms for sesame seed oil were collected and 10 terms of them were screened out by untrained panelists and trained ones. Twenty nine samples were evaluated with 6-scale on 10 terms by three trained panelists. The data obtained were analyzed by principal components (PC) analysis. The samples resulted in nine groups on a scattering plot of the first and the second PC score, whose flavor attributes could be interpreted on the basis of factor loadings. The sesame seed oils by a heat-blast roasting and ones by a far infrared radiation roasting were plotted as separate groups. The former had bitter, astringent and heavy flavor attributes and the deeper roasted ones increased in these flavor attributes as it was. The latter had light, mild, nutty, complicated and aromatic flavor attributes. Complicated and aromatic flavors increased in deep roasted ones, on the other hand, light and mild flavors increased in light roasted ones.

View full abstract

Swelling spoilage of cooked meat products is occasionally caused by gas production of heterofermentative lactic acid bacteria (HLAB). It has been presumed that the swelling spoilage with gas production by HLAB is related to a carbohydrate added in cooked meat products. The effect of various sugars on the gas production by HLAB was examined to prevent the swelling spoilage of cooked meat products. Gas production from sugars, glucose, sucrose, fructose, lactose, sorbitol and maltitol, by HLAB was determined by using following test strains, Lactobacillus viridescens, Leuconostoc mesenteroides and Lactobacillus brevis. The gas volume increased significantly in the broth with glucose, fructose and sucrose. On the other hand, gas production was not observed in the broth containing lactose and sorbitol by test strains. The swelling spoilage of sausages with lactose, sorbitol or without any sugars was not recognized during the 18-day storage. Moreover, addition of maltitol to sausages retarded the occurrence of swelling spoilage. We have a conclusion that the swelling spoilage with gas production by HLAB can be prevented by adding a carbohydrate of lactose, sorbitol, and maltitol to cooked meat products.

View full abstract

[in Japanese]

View full abstract

Using capillary electrophoresis, protein degradation during ripening of Gouda-type cheese manufactured from fresh raw milk was studied. αs0-casein (CN) and αs1-CN degraded in the early stage of ripening (<28 days) so that more than 90% of these proteins were hydrolyzed by 84 day maturation. In contrast, 38, 67 and 84% of αs2-CN, βA1-CN and βA2-CN remained intact, respectively. Para-K-CN derived from K-CN by rennet action also slightly degraded. As ripening progressed, two main casein break down products appeared. From a comparison of the αs0-CN/αs1-CN ratio to that of the break down products, these were considered to be αs0-I-CN and αs1-I-CN (fragment 24-199 derived from αs0-CN and αs1-CN). High correlation coefficient between the αs1-I-CN/αs1-CN ratio and the maturation period (<70 days) which is considered to be a suitable parameter to judge the maturity of cheese was observed.

View full abstract

Addition of lactoperoxidase (LPO) to yogurt softens the hardness of the product. The objective of this study is to clarify the cause of this phenomenon. A mixed culture (Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus, 1:1 ratio) was inoculated into reconstituted skim milk and incubated. After coagulation, the hardness of the gel was measured using a rheometer (Rheoner, Yamaden Inc., Japan). When hypothiocyanite ion (OSCN^-), an oxidation product formed during peroxidase-catalyzed oxidation of thiocyanate (SCN^-), was added to the culture before incubation, the hardness of the gel decreased. To examine the effects of OSCN^- on the hardness of milk gel without any bacterial or proteolytic activities, reconstituted skim milk was acidified by glucono-δ-lactone (GDL). The hardness of GDL-gel was also decreased by addition of OSCN^-. The reactivity of sulfhydryls in β-lactoglobulin was decreased by addition of OSCN^- From these results, it was suggested that OSCN^- modified the milk protein, especially β-lactoglobulin, inhibiting the development of gel network in the LPO-treated yogurt.

View full abstract

Milk fat which has complicated triglyceride composition, is used for bread making, the ingredient of confectionery and the fries under the wide temperature. Application of high pressure to food was attracted recently. The fractionated milk fat which was treated with high pressure was heated for 1hour at 140°C, 180°C or 240°C. The physico-chemical properties of fractionated milk fat by the heating process and high pressure treatment was investigated. The change of weight by heating at 140°C or 180°C was probably the result of oxidization, and that by heating at 240°C was probably formation of breakdown or polymerization. Chemical and physical data, and oxidation products and triglyceride composition analysed by GC indicated that fractionated milk fat deteriorated with rising temperature. Soft fractionated milk fat, has much short chain unsaturated fatty acid and hard fractionated milk fat has much long chain saturated fatty acid. Therefore, soft fractionated milk fat deteriorated rapidly than hard fractionated milk fat. But there was no difference in the property caused by high pressure treatment.

View full abstract

Investigations were carried out to determine the oil content in soybeans by ethyl ether or chloroform-methanol extraction. Samples of 81 domestic and 10 U.S.A. soybeans were used. The amount of chloroform-methanol extracts (y) was higher than that of ethyl ether (x) on % of dry matter basis. Average ratios (y/x×100) were 110.1 (domestic), 113.3 (U.S.A.) and 110.4 (total)%. The calculation formulas using the ethyl ether extract (x) to the chloroform-methanol extract (y) were as follows:
a) Domestic: y=0.89x+4.10 b) U.S.A.:y=0.65x +9.53 c) Total: y=0.86x+4.77

View full abstract

In the cross flow filtration of the fermentation broth in a hollow fiber module, the influence of operating parameters and backwashing operation on the steady state filtration flux, J (l/m² · h), was studied. Cell concentration, Cx(g-dry cell/l), feed velocity, u (m/s) and pressure, ΔP (kPa), were examined as operating parameters. An exponential relationship between the filtration flux and these operating parameters was found and expressed as follows.
J=6.33 cx^-0.25 ΔP^0.38u^0.74 Interval time of 60 min and operation time of 10 sec were obtained for the optimal conditions of backwashing operation by filtrate. By the backwashing operation under the optimal conditions, the filtration flux was a nearly 2-fold larger than that without the backwashing operation. On constant cell concentration, steady filtration flux was observed for a long time. Although the filtration flux calculated from this equation was on an average 27% higher than experimental values, higher correlation between calculated values and experimental values was recognized. From these results, the membrane area required for the bioreactor could be calculated. The calculated membrane area required for a partial discharged cultivation on optimal operation conditions (θ D=0.037h^-1, and θ and D are discharging rate and dilution rate, respectively) was 1/3 that for a complete cell-concentration cultivation. (Received Jun. 23, 1997 ; Accepted Aug. 25, 1997)

View full abstract

The thermal resistant characteristics of spores of thermoacidophile, Alicyclobacillus acidoterrestris, and the inhibitory effect of some food preservatives on the outgrowth of the heat resistant spore were investigated to prevent flat sour type spoilage in acidic beverages. The values of D95°C were about a minute in 20 mM citrate buffer in the pH range of 2.5 to 6.9. The thermal resistance of A. acidoterrestris spores showed a unique characteristic that it did not depend on pH of heating medium over the pH range of 2.5 to 6.9 as compared with that of general Bacillus spores. The D95°C values of them in the acidic beverages were higher than those in the citrate buffer. Accordingly, it might be less effective to lower the pH in food for reducing the thermal resistance of A. acdoterrestris spores. In determining the effect of some food preservatives on the thermal resistance of A. acidoterrestris spores, the addition of lysozyme was effectively contributed to the reduction of their thermal resistance in a citrate buffer at pH 4.0, and also exhibited a similar reducing effect in the acidic beverages. In addition, the outgrowth of A. acidoterrestris spores was inhibited by the addition of lysozyme, polylysine, protamine, acetic acid, sucrose ester or polyglycerol esters in Trypticase Soy Broth at pH 4.0. From these findings, we propose that it would be better to add a lysozyme and another one of the above preservatives at the same time in order to prevent the spoilage caused by A. acidoterrestris in acidic beverages.

View full abstract

For examining the effects of raw soybean preservation on the quality of tofu, seven varieties of raw soybeans were preserved at 15°C followed by analysis of their components, and the quality of tofu prepared from them every other month was evaluated. At 10 months preservation, no significant changes in compositions of monosaccharide and oligosaccharide of preserved soybeans were found for any varieties. However, urease activity, antigenicity and germination rate had decreased to 83.7%, 15.5% and 90.0%, respectively. Examination of the tofu preparations indicated reduction in tofu volume in proportion to the time of preservation. It is thus evident that the properties of soybean changed significantly during preservation, urease activity and antigenicity may be as possible assessment indicators for the quality of tofu prepared from preserved soybeans, though additional research should be conducted for confirmation of this point.

View full abstract