Candida sp. as a starter culture for cocoa (Theobroma cacao L.) beans fermentation

Two cocoa bean fermentation methods (spontaneous fermentation and the use of starter culture) for 7 days fermentation were compared in terms of safety and quality fermented beans. Candida sp. was used as a starter culture in this study. The safety of the fermented cocoa beans were measured by the growth colonies of pathogenic microorganisms namely Bacillus cereus, Escherichia coli, Salmonella sp., Staphylococcus aureus, and Pseudomonas sp., on Bacillus cereus agar, eosin-methylene blue (EMB) agar, xylose lysine deoxycholate (XLD) agar, Baird-Parker agar (BPA), and Pseudomonas agar, respectively. B. cereus, E. coli and Salmonella sp. were early present in both fermentations. Candida sp.-fermentation showed detection of B. cereus at 5.34 log10 CFU/g and absence after 24 hours of fermentation while in spontaneous-fermentation B. cereus was too few to count. Moreover, the log10 E. coli number in Candida sp.-fermentation and spontaneous-fermentation were reduced from 5.72 to 3.66 and from 7.15 to 4.46 on day 1 to day 3, respectively. There were no presences of pathogenic microorganisms on day 5 and day 7 for both fermentations. In term of quality, proximate analysis of spontaneous-fermentation resulted that the content of moisture, ash, fat, crude protein, crude fibre and carbohydrate was 56.47%, 2.32%, 3.17%, 7.02%, 28.14% and 2.88%, meanwhile for the Candida sp.-fermentation was 53.96%, 2.19%, 3.44%, 8.25%, 25.46% and 6.70%, respectively. This study showed that both fermentations are considered to be safe and there is no significant difference in proximate value in fermented cocoa beans from spontaneous-fermentation and Candida sp.-fermentation

Penggunaan spesies ikan air tawar terpilih sebagai penunjuk biologi pencemaran kromium dan selenium di Malaysia

Tiga spesies ikan air tawar iaitu Rasbora sumatrana (Cyprinidae), Poecilia reticulata (guppy; Poeciliidae) dan Carrasius auratus telah didedahkan kepada kromium (Cr) dan selenium (Se) yang mempunyai julat kepekatan yang berbeza selama 4 hari (96 jam) di dalam makmal. Kadar kematian dicatatkan dan kepekatan kematian ambang (LC50) dan masa kematian ambang (LT50) dihitung. Nilai LC50 kepekatan kematian median (LC50) dan masa kematian median (LT50) didapati berkurang dengan peningkatan kepekatan logam dan masa pendedahan bagi kesemua spesies ikan. Nilai LC50 bagi pendedahan selama 96 jam bagi R. sumatrana, P. reticulata dan C. auratus kajian ini masing-masing bagi Cr adalah 20.91, 19.85, 28.31 mg/L dan bagi Se pula 0.21, 3.03, 0.24 mg/L. Se mempamerkan ketoksikan paling tinggi terhadap tiga spesies ikan air tawar ini apabila mempunyai nilai LC50 96 jam paling rendah jika dibandingkan dengan Cr

Creep life prediction of P91 steel using omega method

Martensitic P91 steel is desirable for structural components operating at elevated temperatures. It is extensively used in nuclear power plant boilers, pipelines, reactor pressure vessels, and steam generators due to its high creep strength and corrosion resistance. Predicting the P91’s creep rupture life is critical for safe operation. Numerous creep laws have been developed throughout the years to anticipate the deformation, propagation of damage, and rupture of materials subjected to the creep phenomena. The Omega method is one of the most widely used in API RP579 on fitness-for-service purposes. In this study, the creep tests have been performed at 600 °C for 160, 180 and 190 MPa. In order to predict the rupture life, the omega method has been employed, which utilised the initial creep strain rate and creep strain. The experimental data has been compared to available literature data for P91 material. The predicted life was always more significant than the experimental result, and it was strongly linked to the omega value. The result shows that the value omega value of the test data are in line with the available data and the initial creep strain rate increased linearly with increased of stress and temperature. The predicted rupture life values are consistent and close to the experimental results

BASELINE ASSESSMENT OF STREAM MACROINVERTEBRATE COMMUNITIES AND SEDIMENT NUTRIENT CONTENT IN PANTI FOREST RESERVE, MALAYSIA: IMPLICATIONS FOR BIODIVERSITY AND ECOSYSTEM FUNCTION

Protected regions, such as Malaysia's Panti Forest Reserve (PFR), play a vital role in preserving freshwater biodiversity. However, the absence of baseline data on stream macroinvertebrates and sediment nutrient contents presents a significant challenge. This study, conducted from August 21-24, 2022, as part of the Panti Expedition organized by the Johor State Forestry Department, aimed to investigate the current nutrient flows and stream macroinvertebrates in PFR, providing preliminary assessments. Utilizing kick and grab sampling techniques, we collected stream macroinvertebrates and benthic sediments along the entire upstream-to-downstream gradient of Pelepah Kiri and Gunung Muntahak. Our findings revealed a diverse assemblage of 385 macroinvertebrates from 28 distinct families, with notable abundance observed in Baetidae (14.0%), Simuliidae (10.6%), and Hydropsychidae (10.6%). The analysis of overall taxonomic composition indicated a Jaccard index similarity of 0.64, suggesting overlapping communities between the two sites. Predators were significantly more abundant in Pelepah Kiri, while collectors were more abundant in Gunung Muntahak. The expedition trails exhibited varying levels of moisture content (ranging from 17.2% to 31.3%), total organic carbon content (≤ 0.4%), and total nitrogen levels (ranging from 1,330 mg/kg to 3,180 mg/kg), while phosphorus loading remained undetectable due to low concentration levels. Nutrient analyses indicated no significant impact of total nitrogen on macroinvertebrate family richness, abundance, and diversity. The study's biological metrics demonstrated good stream quality, with taxa richness ranging from 21 to 20 and EPT taxa richness ranging from 6 to 10. These results highlight the diverse freshwater macroinvertebrate communities in PFR, suggesting the maintenance of favorable water quality for biodiversity preservation. Overall, this study provides critical baseline data for future conservation management strategies in PFR, contributing to our understanding of the intricate connections between nutrient dynamics and stream macroinvertebrates in protected area

Fermentation of cocoa (Theobroma cacao L.) beans using Candida sp. and Blastobotrys sp

Spontaneous fermentation often produces a variety of end products. Starter culture has been widely used in many fermented food in order to control fermentation process and produce consistent products. The objective of this study was to evaluate the effect of Candida sp. and Blastobotrys sp. as starters in cocoa bean fermentation in term of optimal media culture, survivability of the cultures and fermentation products of cocoa bean fermentation (pH, temperature, microbial count, proximate analyses, bioactive compounds and volatile compounds). Optimum formulation of molasses yeast extract (MYE) media for the growth of Candida sp. and Blastobotrys sp. was determined using response surface methodology (RSM). Survivability of the cultures was measured by counting of colony-forming units (cfu) on yeast peptone dextrose (YPD) media. Sugar utilization by both types of yeasts in the optimum MYE media were determined using high performance liquid chromatography (HPLC) analysis. The yeasts were then used as a starter culture in cocoa bean fermentation and the products were evaluated for pH, temperature, proximate content, microbial safety and volatile compounds. The results showed that optimal concentrations of MYE medium were determined as follows: Candida sp. (2 g/100 ml, yeast extract; and 10 g/100 ml, molasses) and Blastobotrys sp. (2 g/100 ml, yeast extract; and 1.92 g/100 ml, molasses). The optimum MYE media was able to support the growth of Candida sp. and Blastobotrys sp. up to 140 and 70 days at room temperature, respectively. During survivability of yeasts, both of yeasts rapidly consumed glucose and fructose compared to sucrose at the beginning of the fermentation. Cocoa beans in spontaneous fermentation, Blastobotrys sp.-fermentation and Candida sp.-fermentation raised in temperature from 32°C (day 0) to maximum temperature valued 40°C, 42°C and 43°C after 3 days fermentation, respectively. The pH of cocoa for spontaneous fermentation, Blastobotrys sp.-fermentation and Candidasp.-fermentation at beginning of process were pH 4.07, 4.11 and 4.19, respectively, then the pHs of end products were 5.15, 5.44 and 4.99, respectively. Microbial safety of all type of fermentation showed that the number of E. coli and Salmonella sp. were decreased from 103 - 105 cfu/ml to significant (p<0.05) decreases of crude protein (13.86 - 9.83%), (14.50 - 11.99%) and (14.89 - 13.04%) after 7 days fermentation. Significant decrease in carbohydrate content (32.01% - 12.98%) was observed in spontaneous fermentation only. However, Blastobotrys sp.-fermentation and Candida sp.-fermentation showed increase of carbohydrate value from 9.84 to 19.98% and 22.53 to 22.64%. Spontaneous fermentation showed significant increase in fat (41.51 - 60.32%) and crude fibre content (3.83 - 8.79%) of fermented beans. Significant decreased in ash content for spontaneous fermentation and Blastobotrys sp.-fermentation were (4.44 - 3.06%) and (3.88 - 3.15%), respectively. Significant decreased in moisture content was observed in and Blastobotrys sp.-fermentation (6.84 - 4.71%) and Candida sp.-fermentation (8.20 - 5.69%) but significant increase was observed from spontaneous fermentation (4.34 - 5.02%). Blastobotrys sp.-fermentation product contained low in caffeine (30.59%) while Candida sp.-fermentation product contained low in theobromine (16.53%) but high in stigmasterol (1.68%), beta-sitosterol (3.03%) and tocopherol (5.38%). Fermentation showed a total of 20 volatile compounds related to the desirable notes and off-flavour. High individual compounds of alcohol (5) and ester (6) were detected from Blastobotrys sp.-fermentation compared to spontaneous fermentation; alcohol (3) and ester (4), and Candida sp.-fermentation: alcohol (4) and ester (2). Based on these findings, Candida sp. and Blastobotrys sp. could be used as potential starter cultures for cocoa beans fermentation

Arsenic acute toxicity assessment on select freshwater organism species in Malaysia

Recently, arsenic has contaminated the aquatic ecosystem, raising government and public environmental concern. In this study, four freshwater organisms were used to evaluate arsenic toxicity levels. Two types of fish, namely Poecilia reticulata (guppy) (Poeciliidae) and Rasbora Sumatrana (Cyprinidae), an aquatic worm species Tubifex tubifex (Oligochaeta) and diptera midge larvae Chironomus javanus (Chironomidae) were exposed for a 4-day (96 h) period in laboratory conditions to a range of arsenic (As) concentrations. Mortality was assessed and median lethal times (LT50) and concentrations (LC50) were calculated. The objective of this study is to determine the acute toxicity of arsenic concentration on Poecilia reticula, Rasbora sumatrana, Tubifex tubifex and Chironomus javanus. Results showed that LT50 and LC50 increase with the decrease in mean exposure concentrations and times. Results indicated that Tubifex tubifex was most sensitive to arsenic toxicity compared to other organisms used in this study in this order; Tubifex tubifex > Chironomus javanus > Rasbora sumatrana > Poecilia reticulata