Contribution of 2-methyl-3-furanthiol to the cooked meat-like aroma of fermented soy sauce.

The cooked meat-like aroma compound, 2-methyl-3-furanthiol (2M3F), was detected in fermented soy sauce (FSS) by GC-olfactometry and GC-MS. 2M3F was present in FSS at a concentration considerably greater than the perception threshold, and the 2M3F concentration increased with heating temperature. Sensory analysis indicated that with the addition of only 0.2 µg/L of 2M3F to the soy sauce sample, the cooked meat-like aroma is significantly stronger than that of sample without the addition of 2M3F. Hence, 2M3F contributes to the cooked meat-like aroma of FSS, which constitutes the key aroma component of FSS. In addition, 2M3F was generated from the addition of ribose and cysteine in FSS by heating at 120 °C, but it was not detected in a phosphate buffer under the same condition. Furthermore, 2M3F was not detected in acid-hydrolyzed vegetable-protein-mixed soy sauce (ASS) and heated ASS. These results indicated that fermentation by micro-organisms facilitates the generation of 2M3F in FSS.

Metabolite profiling of soy sauce using gas chromatography with time-of-flight mass spectrometry and analysis of correlation with quantitative descriptive analysis.

Soy sauces, produced from different ingredients and brewing processes, have variations in components and quality. Therefore, it is extremely important to comprehend the relationship between components and the sensory attributes of soy sauces. The current study sought to perform metabolite profiling in order to devise a method of assessing the attributes of soy sauces. Quantitative descriptive analysis (QDA) data for 24 soy sauce samples were obtained from well selected sensory panelists. Metabolite profiles primarily concerning low-molecular-weight hydrophilic components were based on gas chromatography with time-of-flightmass spectrometry (GC/TOFMS). QDA data for soy sauces were accurately predicted by projection to latent structure (PLS), with metabolite profiles serving as explanatory variables and QDA data set serving as a response variable. Moreover, analysis of correlation between matrices of metabolite profiles and QDA data indicated contributing compounds that were highly correlated with QDA data. Especially, it was indicated that sugars are important components of the tastes of soy sauces. This new approach which combines metabolite profiling with QDA is applicable to analysis of sensory attributes of food as a result of the complex interaction between its components. This approach is effective to search important compounds that contribute to the attributes.

A sulfated polysaccharide, fucoidan, enhances the immunomodulatory effects of lactic acid bacteria.

Fucoidan, a sulfated polysaccharide contained in brown algae, has a variety of immunomodulatory effects, including antitumor and antiviral effects. On the other hand, lactic acid bacteria (LAB) also have immunomodulatory effects such as anti-allergic effects. In this study, we demonstrated that fucoidan enhances the probiotic effects of LAB on immune functions. By using Peyer's patch cells and spleen cells in vitro, fucoidan amplified interferon (IFN)-γ production in response to a strain of LAB, Tetragenococcus halophilus KK221, and this activity was abolished by desulfation of fucoidan. Moreover, this IFN-γ response was abolished by interleukin (IL)-12 neutralization. These results indicate that fucoidan enhanced IL-12 production in response to KK221, resulting in promoting IFN-γ production. In an in vivo study, Th1/Th2 immunobalance was most improved by oral administration of both fucoidan and KK221 to ovalbumin-immunized mice. These findings suggest that fucoidan can enhance a variety of beneficial effects of LAB on immune functions.

Naringenin chalcone suppresses allergic asthma by inhibiting the type-2 function of CD4 T cells.

BACKGROUND: Some polyphenols possess anti-allergic activities. Naringenin chalcone is one of the polyphenols that is present in the skin of red tomatoes. In this study, we investigated the effect of naringenin chalcone in allergic responses in vivo using an experimental mouse model system of allergic asthma. METHODS: Allergic airway inflammation was induced in mice by sensitization and challenge with ovalbumin. Naringenin chalcone was orally administrated every day during the course of the experiment. Airway hyperreactivity, the eosinophilic infiltration in the bronchioalveolar lavage fluid and Th2 cytokine production from splenic CD4 T cells were assessed. RESULTS: Eosinophilic airway inflammation, airway hyperreactivity and Th2 cytokine production from CD4 T cells were significantly suppressed in mice that were treated with naringenin chalcone. Hyperproduction of mucus was slightly reduced. CONCLUSIONS: The results of this study suggest that naringenin chalcone suppresses asthmatic symptoms by inhibiting Th2 cytokine production from CD4 T cells. Thus, naringenin chalcone may be a useful supplement for the suppression of allergic symptoms in humans.

Dietary soy isoflavone-aglycone lowers food intake in female rats with and without ovariectomy.

OBJECTIVE: Estrogens downregulate eating behavior, and soy isoflavones are known to be estrogenic agents. We aimed to examine whether the estrogenic property of soy isoflavones can affect food intake and body weight. METHODS AND PROCEDURES: Seven-week-old male, female, and ovariectomized (OVX) Sprague-Dawley rats were given free access to a diet containing 100-300 mg total isoflavone/kg diet, or to a control diet, either with or without concurrent administration of estradiol by subcutaneous implantation. RESULTS: Dietary soy isoflavone was shown to lower food intake in female rats, whether or not the animals had undergone ovariectomy. Administration of estradiol lowered the food intake in male rats and in OVX female rats. The decrease in weekly food intake in female rats led to a reduction in their weekly gain in body weight. Dietary soy isoflavone significantly increased the concentration of serum isoflavones, especially equol (a metabolite of daidzein), regardless of gender or ovariectomy. Dietary soy isoflavone did not affect either serum estradiol concentration or uterine and didymus weights, but estradiol administration improved the uterine atrophy in OVX rats, and decreased the didymus weight in male rats. DISCUSSION: Soy isoflavone lowers the food intake in female rats, but not in the male animals. Contrary to the hypothesis currently in vogue, the reduction in food intake caused by soy isoflavone may not be a purely estrogenic effect. This follows from the finding that the effects of soy isoflavones on food intake and on the reproductive organs differ from the corresponding effects produced by estrogen.

Inhibitory effect of naringenin chalcone on inflammatory changes in the interaction between adipocytes and macrophages.

Obese adipose tissue is characterized by an enhanced infiltration of macrophages. It is considered that the paracrine loop involving monocyte chemoattractant protein (MCP)-1 and tumor necrosis factor (TNF)-alpha between adipocytes and macrophages establishes a vicious cycle that augments the inflammatory changes and insulin resistance in obese adipose tissue. Polyphenols, which are widely distributed in fruit and vegetables, can act as antioxidants and some of them are also reported to have anti-inflammatory properties. Tomato is one of the most popular and extensively consumed vegetable crops worldwide, which also contains many flavonoids, mainly naringenin chalcone. We investigated the effect of flavonoids, including naringenin chalcone, on the production of proinflammatory mediators in lipopolysaccharide (LPS)-stimulated macrophages and in the interaction between adipocytes and macrophages. Naringenin chalcone inhibited the production of TNF-alpha, MCP-1, and nitric oxide (NO) by LPS-stimulated RAW 264 macrophages in a dose-dependent manner. Coculture of 3T3-L1 adipocytes and RAW 264 macrophages markedly enhanced the production of TNF-alpha, MCP-1, and NO compared with the control cultures; however, treatment with naringenin chalcone dose-dependently inhibited the production of these proinflammatory mediators. These results indicate that naringenin chalcone exhibits anti-inflammatory properties by inhibiting the production of proinflammatory cytokines in the interaction between adipocytes and macrophages. Naringenin chalcone may be useful for ameliorating the inflammatory changes in obese adipose tissue.

Lowering effect of an isoflavone-rich fermented soybean extract on the serum cholesterol concentrations in female rats, with or without ovariectomy, but not in male rats.

We examined the effect of administering an isoflavone-rich fermented soybean extract (FSBE) on the serum cholesterol concentrations in male rats and in intact and ovariectomized (OVX) female rats. Dietary FSBE decreased the serum cholesterol concentrations in intact female and OVX rats, but did not affect the concentrations in male rats. Dietary FSBE increased the hepatic total and esterified cholesterol contents in the intact female rats, but decreased them in the OVX rats. This hypocholesterolemic effect was not a simple estrogenic effect because it has appeared in some reports that estrogen administration decreased serum cholesterol both male and female rats. Dietary FSBE increased the hepatic low-density lipoprotein receptor (LDLR) gene expression in the intact female rats as has previously been reported from many studies, but did not affect that of the OVX rats. Further investigation is needed into the hypocholesterolemic mechanism of FSBE.

Anti-allergic activity of naringenin chalcone from a tomato skin extract.

The anti-allergic activity of a tomato extract was studied by using an in vitro histamine-release assay. The tomato skin extract exerted the strongest inhibition of histamine release. Chlorogenic acid, rutin and naringenin were identified in the 60% ethanol extract of tomato skin. However, the extract contained an unknown compound which strongly inhibited histamine release. This active compound in tomato skin was identified as naringenin chalcone (trans-2'4'6'4-tetrahydroxychalcone). Naringenin chalcone inhibited histamine release with an IC(50) value of 68 microg/ml. The anti-allergic activity of the tomato skin extract was next investigated by the in vivo mouse ear-swelling response. We found that naringenin chalcone showed the strongest inhibitory effect of the polyphenols of the tomato skin extract. These results indicate that a tomato skin extract could inhibit allergic reactions.