Nuansri Rakariyatham

Identification of Major Phenolic Compounds from Nephelium lappaceum L. and Their Antioxidant Activities

Nephelium lappaceum is a tropical fruit whose peel possesses antioxidant properties. Experiments on the isolation and identification of the active constituents were conducted, and on their antioxidant activity using a lipid peroxidation inhibition assay. The methanolic extract of N. lappaceum peels exhibited strong antioxidant properties. Sephadex LH-20 chromatography was utilized in the isolation of each constituent and the antioxidant properties of each was studied. The isolated compounds were identified as ellagic acid (EA) (1), corilagin (2) and geraniin (3). These compounds accounted for 69.3% of methanolic extract, with geraniin (56.8%) as the major component, and exhibited much greater antioxidant activities than BHT in both lipid peroxidation (77-186 fold) and DPPH• (42-87 fold) assays. The results suggest that the isolated ellagitannins, as the principal components of rambutan peels, could be further utilized as both a medicine and in the food industry.

Biodegradation of glucosinolates in brown mustard seed meal (Brassica juncea) by Aspergillus sp. NR-4201 in liquid and solid-state cultures.

Aspergillus sp. NR-4201 was assessed by degrading glucosinolates in brownmustard seed meal (Brassica juncea). A liquid culture of the strain, in a medium derived from the meal, produced total degradation of glucosinolates at 32 h. Under these conditions, the glucosinolate-breakdown product, allylcyanide, was formed inculture filtrates. In a plate culture under sterile conditions, the growth of the strain inheat-treated meal media was shown to be effective at 30 °C with 51% moisture,as determined by the measurement of the colony growth rate. On the laboratory scale,solid-state culture under the same conditions gave rise to total glucosinolate degradationwithin 48 h. In comparison, under non-sterile conditions in either heat-treated or nonheat-treated meal samples, the degradations were complete after 60 and 96 h, respectively.In these cases, growth was associated with some out-growths of contaminating fungi,mainly Rhizopus sp. and Mucor sp. The glucosinolate-breakdown product,allylcyanide, was not detected in the solid-state meal-media culture presumably due toevaporative loss from the fermentation matrix.

Rapid detection of myrosinase-producing fungi: a plate method based on opaque barium sulphate formation

A simple and rapid technique to assess the capability of fungi to produce myrosinase is reported. This was carried out by growing the tested fungi in sinigrin–barium agar plates. Strains capable of producing myrosinase were indicated by an opaque barium sulphate zone forming underneath and/or surrounding their colonies. This simple test has been confirmed by determination of myrosinase activity in liquid culture. In positive isolates, enzyme acitivity was detected in cell-free extracts, not in culture filtrates. In the case of non-myrosinase-producing strains, no opaque zone was observed and the enzyme was not detected either in cell-free extracts or in culture filtrates.

Screening of filamentous fungi for production of myrosinase

A linhagem Aspergillus sp. NR46FB, isolada de solo atraves da tecnica do agar sulfato de bario-sinigrina, foi testada quanto a producao de mirosinase. O fungo degradou completamente o glicosinolato e produziu 3,19 U.mL-1 de mirosinase, apos 48 h de cultivo. Devido a alta producao de mirosinase, esse novo isolado e um potente candidato para aplicacoes industriais.

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

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 gas chromatography/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.

Optimization of pineapple pulp residue hydrolysis for lipid production by Rhodotorula glutinis TISTR5159 using as biodiesel feedstock

The higher lipid productivity of Rhodotorula glutinis TISTR5159 was achieved by optimizing the pineapple pulp hydrolysis for releasing the high sugars content. The sequential simplex method operated by varied; solid-to-liquid ratio, sulfuric acid concentration, temperature, and hydrolysis time were successfully applied and the highest sugar content (83.2 g/L) evaluated at a solid-to-liquid ratio of 1:10.8, 3.2% sulfuric acid, 105 °C for 13.9 min. Moreover, the (NH4)2SO4 supplement enhanced the lipid productivity and gave the maximum yields of biomass and lipid of 15.2 g/L and 9.15 g/L (60.2%), respectively. The C16 and C18 fatty acids were found as main components included oleic acid (55.8%), palmitic acid (16.6%), linoleic acid (11.9%), and stearic acid (7.8%). These results present the possibility to convert the sugars in pineapple pulp hydrolysate to lipids. The fatty acid profile was also similar to vegetable oils. Thus, it could be used as potential feedstock for biodiesel production. Graphical abstract High lipid productivity of Rhodotorula glutinis from pineapple pulp residue has obtained via simplex optimization the acid hydrolysis and compositions of hydrolysate.