No abstract

Fish skin, a by-product from fish processing industries, still contains a significant amount of protein-rich material. Gelatin was extracted from Nile tilapia skin with the yield 20.77±0.80 % wet weight. Gelatin was then separately hydrolyzed by proteases, including bromelain, papain, trypsin, flavourzyme, alcalase and neutrase. Low molecular weight gelatin hydrolysate (<10 kDa) has a great potential as an antioxidant agent. Flavourzyme hydrolysate has potent activity on ABTS radical scavenging (1,413.61±88.74 μg trolox/ mg protein) and also inhibits the oxidation of linoleic acid at a high level (59.74±16.57 % inhibition). The greatest reducing power is in alcalase hydrolysate (4.951±1.577 mM trolox/mg protein). While, bromelain hydrolysate has the highest ferrous ion chelating activity (86.895±0.061 %). Evaluation of the angiotensin-I-converting enzyme's inhibitory activity indicates that all hydrolysates have great potency as an antihypertensive agent. All studied tilapia skin gelatin hydrolysates contain potent antioxidant and anti-hypertensive effects.

Gamma-aminobutyric acid (GABA) has many pharmacological functions including being a major inhibitory neurotransmitter. Two comparative methods for GABA production in rice grains as main food source in Thailand were investigated in this study. Fermentation and germination method were separately carried out using seven selected local grain cultivars in northern Thailand. Red yeast rice, obtained from the fermentation method, gave the higher GABA concentration than the germinated rice produced from the germination method in most rice cultivars. The highest GABA concentration was 28.37 mg/ g at 3 weeks fermentation time of glutinous rice, O. sativa L. cv. Sanpatong 1 cultivars, while germinated rice from glutinous rice; O. sativa L. cv. Korkor6 (RD6) cultivars contained the highest GABA concentration of 3.86 mg/g. These results provide information for the basis of an appropriate method for GABA production. The fermentation produced higher GABA concentration but required longer production period and red yeast rice was obtained as product. On the other hand, the germination method yielded rice grains with lower GABA but in more suitable form for consumption. Both methods are considered to be economical and efficient methods to increase GABA in rice grains, providing alternative products with higher nutritional values.

Red yeast rice which is a product of solid fermentation was prepared from several kinds of Thai glutinous rice (Oryza sativa L.) cv. Korkor 6 (RD6), Kam (Kam), and Sanpatong1 (SPT1). Monascus purpureus CMU001 isolated from available Chinese red yeast rice was used as the fermentation starter. The analysis for the presence and the content of monacolins, the cholesterollowering compounds, were carried out using high performance liquid chromatography (HPLC). The presence of the monacolins was confirmed by the retention time of the reference compounds and LC-MS. The results were compared to those obtained from the Chinese red yeast rice and Thai non-glutinous rice (O. sativa L. cv. Mali105). The chromatograms show the presence of monacolin K acid form (MKA), compactin (P1), monacolin M acid form (MMA), monacolin K (MK), monacolin M (MM), and dehydromonacolin K (DMK). A large peak of a compound with the molecular weight of 358 was also detected but could not be identified. The amount of two important monacolins, compactin, and monacolin K, were determined. It was found that the highest amount of compactin and monacolin K were 21.98 and 33.79 mg/g, respectively, when using Thai rice varity O. sativa L. cv. RD6 which was fermented without adding soybean milk.

Abstract-The bird chili powder (Capsicum frutescens Linn.) was a source of aflatoxigenic fungus which was identified as Aspergillus flavus. The antagonist Bacillus subtilis BCC 6327 was shown to inhibit the growth and spore germination of the isolated aflatoxigenic fungus from bird chili powder. All the cell free supernatant from 12, 24 and 36 h of incubation could inhibit the growth and mycelium production with inhibition percentages of 92.1, 89.6 and 90.1%, respectively. Growth of aflatoxigenic fungi was inversely correlated with enzyme productions from B. subtilis. Productions of protease, chitinase and β-1,3-glucanase and the released sugars (total reducing sugar, glucose and N-acetylglucosamine) were enhanced by the dried fungal mycelia. B. subtilis culture filtrates, possessing protease, chitinase and β-1, 3-glucanase, were capable of hydrolyzing dried mycelia of the isolated aflatoxigenic fungi from bird chili powder.