Crustacean protein (tropomyosin) has frequently been detected in processed foods containing seaweed. In Japanese regulations for the labeling of allergenic food ingredients, the PCR method for detecting extracted shrimp/prawn and crab DNA is stipulated to discriminate shrimp/prawn and crab in processed foods. It has, however, been difficult to extract shrimp/prawn and crab DNA in processed foods including seaweed. We modified the DNA extraction protocol of the DNeasy mericon Food kit, and compared the yield and purity of DNA extracted from dried seaweed powder containing 1, 5, 10, 100, or 10,000 μg/g of freeze-dried edible shrimp/prawn or crab using various commercially available DNA extraction kits. The improved DNA extraction method provided sufficient yield and purity of extracted DNA suitable for the detection of specific DNA using the PCR method. To directly evaluate the applicability of the DNA extraction method, we employed PCR amplification with primers (PyrbcL01-5'/PyrbcL01-3') designed for the detection of the Pyropia yezoensis rbcL gene. The primer pair could generate amplicons from several commercial nori food products and dried seaweed powder containing shrimp/prawn or crab. The limit of detection for shrimp/prawn or crab DNA extracted by the improved DNA extraction method is 1 μg per g dried seaweed powder. In conclusion, we showed that the improved method is simple, rapid and highly sensitive, and can be used to detect shrimp/prawn and crab DNA in dried seaweed food products.

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A psychological experiment was conducted to show the effect of pamphlets about food additives on consumers' attitude with 120 female undergraduate students in Tokyo, Japan. The results showed that giving information about the benefits of food additives through pamphlets increased understanding and acceptance of food additives among the participants. We also found that this effect persisted for more than three months at least. In contrast, risk literacy information provided via pamphlets led to a greater increase in understanding and acceptance about food additives among the participants immediately after the experiment, but the effect soon reduced in magnitude and faded after three months.

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Renin is an important target for inhibition to treat high blood pressure. The enzyme catalyzes the first rate-determining step in the renin angiotensin system (RAS), which controls blood pressure in mammals. Renin-inhibitory compounds have been found in several foodstuffs, such as soybeans and cereals, and certain saponins and unsaturated fatty acids have been identified as such. The present study determined the surface plasmon resonance (SPR) responses of various saponins and unsaturated fatty acids using recombinant human (rh)-renin, which was produced with an insect cell-baculovirus expression system and immobilized to sensor chips. We demonstrated that there is a qualitative correlation between SPR responses and half-maximal (50%) renin inhibitory concentration. In addition, the SPR responses of several legume extracts with the immobilized rh-renin agreed for the most part with their reported inhibitory activity. These results indicate that SPR analysis using immobilized rh-renin is applicable to the screening of potential renin-inhibitory compounds in natural foodstuffs.

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The applicability of a taste sensing system was assessed by evaluating the taste qualities of 9 natural bittering food additives, 22 bittering reagents and 3 astringent reagents. The intensities of 10 taste factors for each sample were calculated from data collected from 6 artificial lipid membranes attached to the taste sensing system. The intensity of the taste factor with the highest absolute value for each sample was assigned a value of 100, and the intensities of the other taste factors for the same sample were provided as relative percentage values. The relative percentage values were plotted on radar charts for each sample, and the taste qualities of the samples were compared based on the radar chart patterns. The taste quality of samples was roughly classified into five types based on their taste quality patterns. Taste quality type appears to be characterized by the chemical structure of the bittering substance, since samples containing similar bittering constituents showed similar taste quality patterns. In addition, principal component analysis (a multivariate analysis) using the relative percentage values of 10 taste factors for each sample clearly classified the five types of taste qualities of bittering substances. This study demonstrated the applicability of the taste sensing system to evaluate the taste qualities of natural bittering food additives and bittering reagents. The results suggest that the chemical structure types of unidentified bittering constituents in bittering substances can be estimated using the taste sensing system to evaluate taste qualities. These results should also be useful to evaluate the taste qualities of other commercially available bittering products as well as food additives.

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Glycyrrhizic acid (GA), a triterpenoid saponin containing two glucuronic acid (GlcA1 and GlcA2) units, is found in the roots of Glycyrrhiza plants, and has been widely used as a natural sweetener for foods as well as a natural medicine. Purified GA is commercially available from various manufacturers as an analytical standard or a biochemical reagent. While producers describe the configurations of GlcA1 and GlcA2 as α and β-forms, respectively, reports of the structural elucidation of GA have proposed that both GlcA units are β-form. To clarify this point, commercial GA from various sources was analyzed by 1D and 2D NMR studies. Results confirmed that the actual configuration of both GlcA units in GA is β-form.

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The modified glycosides prepared from various flavonoids are attractive materials for the production of functional foods. In this study, the conversion of eriocitrin, a major flavonoid in lemon peel, to its monoglucoside, eriodictyol-7-O-β-glucoside (eriodictyol-7-glucoside), was studied using acidic and enzymatic hydrolysis methods. eriodictyol-7-glucoside is a promising bioactive compound having a potent α-glucosidase-inhibitory activity. The conversion of eriocitrin to eriodictyol-7-glucoside by acidic hydrolysis reached to a maximum yield of 25%. When hesperidinase and naringinase were used as catalysts, the transformation rates from eriocitrin to eriodictyol-7-glucoside reached to approximately 80% and 70%, respectively, under the controlled reaction conditions. Furthermore, hesperidinase and naringinase showed similar time-course profiles on the hydrolysis of eriocitrin. These results indicate that the efficient and selective production of the reaction intermediate from eriocitrin could be accomplished by the enzymatic hydrolysis.

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The purpose of this research was to evaluate the safety of tekikamomo (thinning out peaches) as a food material. We carried out qualitative tests of cyanogenic glycosides and free cyanide, which is derived from cyanogenic glycosides. No free cyanide was detected in tekikamomo boiled for 15 minutes. On the other hand, the cyanogenic glycoside prunasin remained in tekikamomo boiled for 60 minutes. Next, we conducted an oral dose toxicity test in a single time using rats and tekikamomo boiled for 15 minutes. Our results suggests the possibility that tekikamomo boiled for more than 15 minutes is safe for consumption and can be used for food materials.

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In this study, the analytical method was developed for the simultaneous analysis of the two components of phthalide group, those are ligustilide and butylidene phthalide, and the three components of furocoumarin group, those are psoralen, xanthotoxin and bergapten, in angelicae leaves and stems using high performance liquid chromatography (HPLC). The components in angelicae leaves and stems tracted with methyl alcohol using an ultrasonic bath. HPLC was performed on an Inertsil ODS-3 column (4 μm, 4.6 mm i.d.×150 mm) with ultraviolet detection set to 240 nm, using H₂O-acetonitrile in the mobile phase. The measurement of the concentration of each component in angelicae leaves and stems by the above mentioned method showed the following results: ligustilide 1678〜12363 μg/g, butylidene phthalide 199.3〜362.5 μg/g, xanthotoxin 65.4〜271.0 μg/g and bergapten 137.4〜299.3 μg/g, and psoralen was under the limit of quantification.

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As a part of researches for endogenous proteinases, we attempted with purification and characterization of a cysteine protease active in neutral pH from the spleen of chub mackerel Scomber japonicus. The molecular mass of the purified enzyme was estimated to be 35 kDa by gel filtration. In addition, the purified enzyme was detected as two protein bands of 35 and 27 kDa by SDS-PAGE, and N-terminal amino-acid sequences of the former and latter shared high homology with those of single and heavy chains, respectively, of rainbow trout, mouse, and bovine cathepsin B. The optimum pH of the purified enzyme were 7.0 and 7.7, respectively, on Z-Phe-Arg-MCA and Z-Arg-Arg-MCA hydrolyzing activity. The activity was suppressed by cysteine protease inhibitors such as E-64, TLCK, and leupeptin. From these results, the purified enzyme active in neutral pH was considered to be a new type of cathepsin B, which was different from well-known cathepsin B active in acidic conditions. Moreover, myosin heavy chain and actin were hydrolyzed with addition of the enzyme in neutral pH, suggesting that the cathepsin B-like enzyme purified from the spleen of chub mackerel is one of the proteases responsible for post-mortem fish muscle tenderization.

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Parachlorella kessleri strain KNK-A001 is a green microalga taxonomically related to P. kessleri. This alga has a thick extracellular matrix instead of a usual hard cell wall. We have previously found that dry powdered KNK-A001 has good food value as feed for the Pacific oyster spat and zooplankton rotifer Brachionus plicatilis. In this study, we investigated the effects of dry powdered KNK-A001 on mammalian immune systems and compared with those of Chlorella vulgaris. The cell suspensions of these microalgae were prepared with phosphate buffered saline, and autoclaved before use. When the cell suspension of C. vulgaris was added to mouse macrophage cell line RAW264.7 cells, the significant increase of nitric oxide (NO) levels and tumor necrosis factor-α (TNF-α) were induced in a concentration-dependent manner, whereas KNK-A001 cell suspension showed no such stimulating activities on RAW264.7 cells up to 1,000 μg/mL. On the other hand, intraperitoneal injection of KNK-A001 cell suspension into mice resulted in a significant increase in splenic natural killer (NK) cell activity against YAC-1 cells, which was even much higher than that induced by C. vulgaris. Infrared spectral analysis and alginate lyase-digestion test suggested that KNK-A001 had abundant alginate. Our results suggest that KNK-A001 cell suspension may have specific immune potentiating activities.

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