40 research outputs found

    Volatile compounds of vegetarian soybean kapi, a fermented Thai food condiment

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    Kapi is a traditional shrimp paste used as a food condiment in Thailand. Several vegetarian soybean kapi, S1-S5, were fermented from various bacterial starter cultures isolated from commercial shrimp paste. The volatile compounds of S1-S5 were analyzed using SPME coupled with gaschromatography/mass spectrometry and compared to three samples of commercial vegetarian kapi (J1-J3) and commercial shrimp pastes  (K1-K3). 124 volatile compounds consisting of aldehydes, alcohols, ketones, acids and esters, N-containing compounds, aromatic compounds, S-containing compounds, miscellaneous, indoles and hydrocarbons were identified. Principle component analysis and cluster analysis separated the volatile profile of the fermented samples into four groups. Vegetarian soybean kapi, S1, S4 and S5 produced from Bacillus subtilis IS4, TISTR10 and TISTR1, respectively, were classified into the following groups containing commercial kapi (J1, J2, K2 and K3), that had a predominance of indole, S-containing and N-containing compounds. Sensory evaluation of S1 showed a strong kapi odor with higher scores among the vegetarian soybean kapi and there were no significant differences in evaluation scores between S1 and commercial vegetarian kapi J1-J3. These data demonstrate that B. subtilis IS4 can be employed as a starter culture to produce an acceptable vegetarian soybean kapi substitute for shrimp paste kapi.Key words: Vegetarian kapi, volatile compounds, fermentation, principal component analysis, cluster analysis

    Volatile compounds of vegetarian soybean kapi, a fermented Thai food condiment

    Get PDF
    Kapi is a traditional shrimp paste used as a food condiment in Thailand. Several vegetarian soybean kapi, S1-S5, were fermented from various bacterial starter cultures isolated from commercial shrimp paste. The volatile compounds of S1-S5 were analyzed using SPME coupled with gaschromatography/mass spectrometry and compared to three samples of commercial vegetarian kapi (J1-J3) and commercial shrimp pastes (K1-K3). 124 volatile compounds consisting of aldehydes, alcohols,ketones, acids and esters, N-containing compounds, aromatic compounds, S-containing compounds, miscellaneous, indoles and hydrocarbons were identified. Principle component analysis and cluster analysis separated the volatile profile of the fermented samples into four groups. Vegetarian soybean kapi, S1, S4 and S5 produced from Bacillus subtilis IS4, TISTR10 and TISTR1, respectively, were classified into the following groups containing commercial kapi (J1, J2, K2 and K3), that had a predominance of indole, S-containing and N-containing compounds. Sensory evaluation of S1 showed a strong kapi odor with higher scores among the vegetarian soybean kapi and there were no significant differences in evaluation scores between S1 and commercial vegetarian kapi J1-J3. These data demonstrate that B. subtilis IS4 can be employed as a starter culture to produce an acceptable vegetarian soybean kapi substitute for shrimp paste kapi.Key words: Vegetarian kapi, volatile compounds, fermentation, principal component analysis, cluster analysis

    Improvement of myrosinase activity of Aspergillus sp. NR4617 by chemical mutagenesis

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    A myrosinase (thioglucoside glucohydrolase or thioglucosidase, EC 3.2.3.147) producing fungus, Aspergillus sp. NR4617, was newly isolated from decayed soil sample obtained in Thailand and was subjected to single exposure to two chemical mutagens, ethyl methanesulfonate (EMS) and N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). Its myrosinase production was selected on low cost medium prepared from mustard seed cake ( Brassica juncea ). Studies of production and stability of the enzyme showed that EMS mutagenesis increased myrosinase activity. Aspergillus sp. NR4617E1 produced myrosinase 1.90 U ml-1 at 36 hrs of the cultivation equivalent to 171% of the enzyme production in wild-type. The stability studies revealed that myrosinase from the mutant strains retained activity similar to wild-type at 30\ub0C. Aspergillus sp. NR4617E1 degraded 10 mM of glucosinolate completely in 36 hrs. Enhanced myrosinase production and high yields of products (allylisothiocyanate) demonstrated that this mutant could be a new found candidate for feed detoxification and industrial allylisothiocyanate production

    Microbial inactivation and cytotoxicity evaluation of UV irradiated coconut water in a novel continuous flow spiral reactor

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    A continuous-flow UV reactor operating at 254 nm wave-length was used to investigate inactivation of microorganisms including bacteriophage in coconut water, a highly opaque liquid food. UV-C inactivation kinetics of two surrogate viruses (MS2, T1UV) and three bacteria (E. coli ATCC 25922, Salmonella Typhimurium ATCC 13311, Listeria monocytogenes ATCC 19115) in buffer and coconut water were investigated (D10 values ranging from 2.82 to 4.54 mJ·cm− 2). A series of known UV-C doses were delivered to the samples. Inactivation levels of all organisms were linearly proportional to UV-C dose (r2 \u3e 0.97). At the highest dose of 30 mJ·cm− 2, the three pathogenic organisms were inactivated by \u3e 5 log10 (p \u3c 0.05). Results clearly demonstrated that UV-C irradiation effectively inactivated bacteriophage and pathogenic microbes in coconut water. The inactivation kinetics of microorganisms were best described by log linear model with a low root mean square error (RMSE) and high coefficient of determination (r2 \u3e 0.97). Models for predicting log reduction as a function of UV-C irradiation dose were found to be significant (p \u3c 0.05) with low RMSE and high r2. The irradiated coconut water showed no cytotoxic effects on normal human intestinal cells and normal mouse liver cells. Overall, these results indicated that UV-C treatment did not generate cytotoxic compounds in the coconut water. This study clearly demonstrated that high levels of inactivation of pathogens can be achieved in coconut water, and suggested potential method for UV-C treatment of other liquid foods. Industrial relevance This research paper provides scientific evidence of the potential benefits of UV-C irradiation in inactivating bacterial and viral surrogates at commercially relevant doses of 0–120 mJ·cm− 2. The irradiated coconut water showed no cytotoxic effects on normal intestinal and healthy mice liver cells. UV-C irradiation is an attractive food preservation technology and offers opportunities for horticultural and food processing industries to meet the growing demand from consumers for healthier and safe food products. This study would provide technical support for commercialization of UV-C treatment of beverages

    Méthode de classification multidimensionnelle (spectrale et texturale) appliquée a des images satellite

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    Les méthodes de classification supervisées multi-spectrales n'offrent pas toujours des résultats satisfaisants. Certaines classes restent spectralement confondues. Une solution apportée à ce problème consiste à introduire dans la classification une information supplémentaire d'ordre textural, ce qui permet de simuler une partie de l'interprétation visuelle. Un objet dans une image se reconnaît à sa couleur mais également à la distribution des tons de gris de son environnement immédiat. Ainsi, dans la méthode de classification présentée, l'appartenance d'un point à une classe est déterminée en tenant compte d'une part des critères spectraux, d'autre part d'un critère spatial. La méthode de classification comporte deux étapes Dans un premier temps, est effectuée une classification multispectrale. Lorsqu'un point appartient à plusieurs classes, la deuxième étape est appliquée afin de décider de l'affectation de ce point à une classe unique en calculant des fréquences conditionnelles des tons de gris du voisinage de ce point. La distribution de fréquences ainsi obtenue est comparée aux distributions de fréquences des différentes classes auxquelles ce point avait été affecté initialement. La méthode étant supervisée, les échantillons permettent de connaître la distribution représentative de chaque classe. La méthode a été testée sur plusieurs types d'images satellite (SPOT et LANDSAT). L'établissement des matrices de confusion des classes et l'évaluation a posteriori de la classification montrent que cette méthode apporte une amélioration de la cartographie

    An alternative synthesis of (±)-phenylephrine hydrochloride

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    This study presents alternative synthetic pathways and reagents for the preparation of racemic phenylephrine hydrochloride. Using m-hydroxybenzaldehyde as starting material, two separate pathways–epoxidation and bromohydrin formation–are presented. Both routes provide good yields (overall of 71% and 66% respectively) and can be performed at mild conditions
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