Ambient Tropical Temperature Research Articles

Diversity of Anammox Bacteria from Landfill Treatment Plant Sludge in Tropical Area

The anaerobic ammonium oxidation (anammox) process is known as the warm process. Tropical areas have an advantage due to their consistent temperature throughout the year. This study analyzed the diversity of anammox bacteria in the tropical area using leachate sludge from a landfill as an inoculum in a filter bioreactor (FtBR) and observed nitrogen removal performance. Ammonium and nitrite concentrations of 70, 150, and 200 mg-N/L were delivered into the reactor continuously with hydraulic retention time (HRT) of 24 h and 12 h and run for 131 days at ambient tropical temperature (25–28 °C). High performance achieved with nitrogen removal rate (NRR), nitrogen removal efficiency (NRE), and ammonium conversion efficiency (ACE) were 0.866 kg-N/m3.d, 99.19%, and 98.90%, respectively. The cultivated leachate sludge could perform an anammox process with four anammox species, Candidatus Brocadia fulgida, Candidatus Brocadia sapporoensis, Candidatus Brocadia sp uncultured, Candidatus Jettenia sp with abundance 6.52%, 13.82%, 0.77%, and 0.69%, respectively. These findings contribute to the advancement of biotechnology in wastewater treatment, particularly in tropical countries, and highlight the potential for highly cost-effective technology.

Physical quality changes of dehydrated strawberry affected by different packaging in a tropical environment

Processed fruit strawberry such as dehydrated fruit was important as alternative ways to increase shelf-life and value of the fresh fruit. However, the unfavorable effects of the tropical environment can accelerate the deterioration quality of processed fruit. Applied packaging to protect the processed fruit was an important way to maintain the quality and increasing the shelf-life of the fruit. The objective of the study wants to know the effects of different packaging treatments for reducing unfavorable tropical environment conditions of dehydrated strawberry fruit. Dehydrated fruit strawberry was made using a combination of pre-treatment by osmotic dehydration with hot air convective drying method. The combination for treatments of material and process for production dehydrated strawberry used is a drying temperature of 70°C, concentrate osmotic agents with 50°Brix, immersion time for 60 min, and drying time of 6 h until 9 h.The dehydrated strawberry fruit was packaging used Polyethylene plastic with Nylon that and stored in the ambient tropical temperature condition. Firstly, dehydrated strawberry fruit packaged conventionally using Polyethylene plastics with Nylon packaging with vacuum treatment and secondly, dehydrated fruit without packaging as a control. Physical parameters were analyzed using standard method texture and color of food. Based on the result, vacuum packaging treatments for the treatment of 70°C; 50°Brix; 60 min; 9 h; 36 h can be maintained the color changes and texture of dehydrated strawberry fruit compare with those of control.However, detailed changes in chemical quality and different thickness of vacuum bag packaging needed to be considered for future research.

The impact of storage conditions on human stool 16S rRNA microbiome composition and diversity.

BackgroundMultiple factors can influence stool sample integrity upon sample collection. Preservation of faecal samples for microbiome studies is therefore an important step, particularly in tropical regions where resources are limited and high temperatures may significantly influence microbiota profiles. Freezing is the accepted standard to preserve faecal samples however, cold chain methods are often unfeasible in fieldwork scenarios particularly in low and middle-income countries and alternatives are required. This study therefore aimed to address the impact of different preservative methods, time-to-freezing at ambient tropical temperatures, and stool heterogeneity on stool microbiome diversity and composition under real-life physical environments found in resource-limited fieldwork conditions.MethodsInner and outer stool samples collected from one specimen obtained from three children were stored using different storage preservation methods (raw, ethanol and RNAlater) in a Ugandan field setting. Mixed stool was also stored using these techniques and frozen at different time-to-freezing intervals post-collection from 0–32 h. Metataxonomic profiling was used to profile samples, targeting the V1–V2 regions of 16S rRNA with samples run on a MiSeq platform. Reads were trimmed, combined and aligned to the Greengenes database. Microbial diversity and composition data were generated and analysed using Quantitative Insights Into Microbial Ecology and R software.ResultsChild donor was the greatest predictor of microbiome variation between the stool samples, with all samples remaining identifiable to their child of origin despite the stool being stored under a variety of conditions. However, significant differences were observed in composition and diversity between preservation techniques, but intra-preservation technique variation was minimal for all preservation methods, and across the time-to-freezing range (0–32 h) used. Stool heterogeneity yielded no apparent microbiome differences.ConclusionsStool collected in a fieldwork setting for comparative microbiome analyses should ideally be stored as consistently as possible using the same preservation method throughout.

Effect of Packaging Material on Shelf Life and Quality of Ware Potato Tubers Stored at Ambient Tropical Temperatures

The effect of seven packaging materials (transparent perforated and non-perforated high-density polyethylene (HDPE) bags, black perforated and non-perforated low-density polyethylene (LDPE) bags, nylon gunny sacks, khaki bags and net bags) on post-harvest quality of tubers from three potato cultivars was evaluated. Data were collected on time and percentage of sprouting, weight loss rates and percentage tubers with greening and rotting. Packaging significantly reduced weight loss and rate of tuber greening but increased the rate of sprouting and decay incidences. Non-perforated PE bags were the most effective in reducing weight losses, recording losses of 0.7 to 0.9% after 32 days in storage while unpackaged tubers had weight losses of 11 to 12%. Tuber rotting was highest (60 to 66% of the tubers) in non-perforated PE bags. Greening was faster in non-packaged tubers recording 55 to 100% after 2 weeks in storage and showed high cultivar differences, but did not occur in black bags, whether perforated or non-perforated. Sprouting was complete by week 3 in all tubers packaged in non-perforated HDPE bags irrespective of cultivar. Although the non-perforated HDPE bag packaging prevented weight loss, its positive effect was counteracted by the high incidence of rotting and sprouting. Amongst the different materials evaluated, perforated low-density black PE bags were the best method for ware potato packaging due to low sprouting, reduced weight loss, low rate of tuber greening and reduced rate of tuber decay compared to other packaging materials. The study also indicated that the interaction between cultivars, packaging and storage period also affected shelf life of ware potatoes under ambient tropical conditions.

Preservative Activity of Ethanolic Extract of Ginger in Wara - A West African Traditional Soft (Unripened) Cheese

The effect of ethanolic extract of ginger (Zingiber officinale) on sensory and storage qualities of wara was evaluated. Pasteurized fresh milk samples were used to prepare wara and; 1.6%, 2.4%, 3.2% and 0% ginger extracts (samples A, B, C and D respectively) were incorporated into the samples separately. The wara samples were then fried in hot palm oil as it is done traditionally and organoleptic properties of the samples were determined by a taste panelist. Also physico-chemical and microbiological changes during six (6) days storage at ambient tropical temperature (30 ± 2oC) were determined. The samples (A, B and C) containing ginger were rated better than the control sample (D). Sample C had the highest overall acceptability of 4.0 while sample D had the least (2.8). During storage a significant decrease (P≤0.05) in pH with a corresponding increase in titratable acidity (TA) was recorded for the wara samples. The pH ranged between 4.17 and 6.55 while the TA ranged between 0.018 and 0.099 (mg/100g).The peroxide values (POV) of sample D increased at a faster rate than samples A, B and C. The POV for sample D after 3 days of storage was 34.15 meq/kg while that of sample C was 25.33 meq/kg at the end of 6 days storage. Although there was general increase in the microbial loads (MLs) of all the samples, the MLs of samples A, B and C were significantly lower than that of sample D. Moreover samples A and B got spoilt by day 4 of storage; sample D by day 3 while sample C was still in good condition at the end of 6 days storage. This study therefore showed that incorporation of 3.2% ethanolic ginger extract significantly improved acceptability of wara and increased the shelf life of the product by 3 days.

Production of salted and pressed anchovies (stolephorus sp.) and it’s quality evaluation during storage

Present study deals with the production of low cost salted and dried product from anchovy fish (Stolephorus spp.) using traditional technology application of different inhibitory factors to achieve a reasonable shelf life at ambient tropical temperature. Microbial safety, nutrient retention and product quality in terms of flavor and texture after rehydration have been tested. This product has been subjected to storage studies, with respect to product quality and microbial status. It can be kept well for a period of 5weeks. The quality changes during storage are; decrease in sensory scores for the overall acceptance and also for the individual attributes. Increase in nitrogenous components such as Total Volatile Bases Nitrogen (TVB-N), Tri Methyl Amine Nitrogen (TMA-N) and Alpha Amino Nitrogen (AAN) was obtained with the advancement of the storage period. The lipid quality of the fish showed gradual increase in Preoxide Value (PV) and Free Fatty Acid (FFA) accompanied by decrease in flavor and odor scores. Activity of microorganisms showed a marginal increase with increase in storage period.

PREPARATION OF BOILED AND DRIED PRODUCTS FROM ANCHOVIES (STOLEPHORUSSP.) AND STUDIES ON QUALITY CHANGES DURING STORAGE

In the present study, a low-cost boiled and dried product from anchovies has been developed by using simple traditional technology involving the application of different inhibitory factors to achieve a reasonable shelf life at ambient tropical temperature. Microbial safety, nutrient retention and product quality in terms of flavor and texture after rehydration have been achieved. This product has been subjected to storage studies, with respect to product quality and microbial status. It can be kept well for a period of 15 weeks. The quality change during storage was a decrease in sensory scores for the overall acceptance and for the individual attributes. An increase in nitrogenous components such as total volatile bases nitrogen, trimethylamine nitrogen and alpha amino nitrogen was obtained with the advancement of the storage period. The lipid quality of the fish showed gradual increase in peroxide value and free fatty acid accompanied by a decrease in flavor and odor scores. The activity of microorganisms persisted in spite of several inhibitory factors. It showed a marginal increase with increase in storage period. The boiled and dried anchovy is a ready-to-eat product, or it can be lightly fried along with spices. PRACTICAL APPLICATIONS The three important pelagic species of India are mackerels, sardines and anchovies. Anchovies are small saltwater fish that grow up to 20 cm (8 in.) and prefer the warmer waters around the world. The limiting factors in the effective utilization of anchovies are their small size, the seasonal nature of the fishery forming gluts and their sensitivity to physical, time and temperature abuses. Anchovies are rich in omega-3 oils, calcium and iron. They can be cooked fresh, usually sold packed in salt, tinned in oil, as a paste in jars or tubes, or as a sauce. A low-cost boiled and dried product was developed by using simple traditional technology involving the application of different inhibitory factors to achieve a reasonable shelf life at ambient tropical temperature. Microbial safety, nutrient retention and product quality in terms of flavor and texture after rehydration have been achieved. It can be kept well for a period of 15 weeks. The boiled and dried anchovy is a ready-to-eat product, or it can be lightly fried along with spices.

PREPARATION OF PICKLED PRODUCT FROM ANCHOVIES(STOLEPHORUS SP.)AND STUDIES ON QUALITY CHANGES DURING STORAGE

ABSTRACT In the present study, low cost anchovy pickled product has been developed using traditional technology application of different inhibitory factors to achieve a reasonable shelf life at ambient tropical temperature. Microbial safety, nutrient retention and product quality in terms of flavor and texture after rehydration have been tested. This product has been subjected to storage studies, with respect to product quality and microbial status. It can be kept well for a period of 15 weeks. The quality changes during storage are decreased in sensory scores for the overall acceptance and also for the individual attributes. Increase in nitrogenous components such as total volatile bases nitrogen, trimethylamine nitrogen and alpha amino nitrogen was obtained with the advancement of the storage period. The lipid quality of the fish showed gradual increase in preoxide value and free fatty acid accompanied by decrease in flavor and odor scores. Activity of microorganisms showed a marginal increase with increase in storage period. It is ready-to-eat product or can be lightly fried along with spices. PRACTICAL APPLICATIONS Anchovies are one of the important pelagic fish species found in the Indian Ocean, which can grow up to 20 cm (8 in), and prefer the warmer waters around the world. The limiting factors in the effective utilization of anchovies are their small size, seasonal nature of the fishery forming gluts, sensitive to physical, time and temperature changes. Anchovies are rich in omega-3 oils, calcium and iron. They can be cooked fresh, usually sold packed in salt, tinned in oil, as a paste in jars or tubes, or as a sauce. Anchovy pickled products have been developed using application of different inhibitory factors to achieve a reasonable shelf life at ambient tropical temperature. Microbial safety, nutrient retention and product quality in terms of flavor and texture after rehydration have been tested. This product has been subjected to storage studies, with respect to product quality and microbial status. It can be kept well for a period of 15 weeks. Activity of microorganisms showed a marginal increase with increase in storage period. It is a ready-to-eat product or can be lightly fried along with spices. This product is helpful in value addition and better utilization of anchovy catch.

Physiological quality of hybrid maize seeds during containerized-dry storage with silica gel

Seed storage operations in the tropics would benefit from low input techniques that can maintain seed physiological quality for considerably long periods without investments in cooling. A study was conducted to evaluate seed vigour and estimate seed longevity in maize during dry storage with commercial desiccant (silica gel) at various levels of gel/seed ratios in air-tight containers under ambient tropical temperature. Seed moisture content (MC) was lowest indicating effective drying at 1:1 gel/seed (100 g of seed stored over 100 g of gel) and 1:2.5 gel/seed ratio (100 g of seed stored over 80 g of gel) during 2 trials set up in 2005 and 2006. After 4 months of storage, laboratory seed germination capacity and vigour variables were consistently higher (p<0.05) in seed lots stored at 1:1 and 1:2.5 gel/seed ratios than seed lots stored at 1:20, 1:10 and 0:1 gel/seed ratios in the 2 trials. Probit analysis of seed survival data from controlled deterioration (CD) tests showed that estimates of potential longevity were optimal at 1:2.5 gel/seed ratios in the two experiments. The results indicated the possibility of maintaining seed physiological quality in containerized-dry storage under ambient humid tropical storage conditions. Moreover, the storage system experimented in the study simulated a condition that eliminates labour involved in regenerating or drying silica gel, since silica gel was not changed throughout the storage period. Gel/seed ratios between 1:1 and 1:2.5 are recommended for direct application or in developing technology and equipment for containerized-dry seed storage in the humid tropics.

Demonstration of anaerobic stabilization of black water in accumulation systems under tropical conditions

The anaerobic digestion of “human waste” was studied at Mlalakuwa residential settlement in Dar-es-Salaam, Tanzania at ambient tropical temperatures (24–31 °C). This settlement experiences a high water table with flooding during the rainy season, resulting in a very costly emptying of the latrines once per month. To improve the situation, two plastic tanks (while one is in use, the other one is on stand-by) of 3000 l capacity each, named as Improved Pit- Latrines Without Urine Separation (IMPLWUS), were used as latrine pits. They received faeces + urine + wash water; basically, an accumulation system. Septic tank seed sludge was used. The dissolved chemical oxygen demand (COD dis) remaining when the reactor was closed after 380 days was about 8 g COD/l, volatile fatty acids were 100 mg COD/l and total ammonium nitrogen was about 2.8 g N/l, implying the possibility of methanogenesis inhibition. Stability results indicated a need for more degradation time after reactor closure. Estimated biogas production from wastewater generated by 10 people was 544 g COD-CH 4/day, not enough for cooking purposes.

Rotavirus particles can survive storage in ambient tropical temperatures for more than 2 months.

Typing and in vitro cultivation of rotavirus-positive human stool samples stored unintentionally at ambient tropical temperatures for 2 1/2 months showed that rotavirus is stable and may still be infectious in vitro. This indicates that stool specimen collection for rotavirus studies can be performed in areas and settings where reliable cold storage is not available. The retained infectivity of rotavirus particles underscores the need for safe systems for disposal of feces, in particular in developing countries where rotavirus is a major cause of childhood mortality.

Antivenoms

The first advance on crude filtered immune serum or plasma for treating systemically envenomed bite victims was the use of IgG (predominantly equine) precipitated by salt treatment. This was followed by the development of F(ab')(2) antivenoms, prepared using pepsin digestion to remove both the highly reactive and nonspecific Fc part of the IgG molecule and also other non-antibody proteins from the material. Within normal limitations, both monospecific (raised against the venom of a single species) and polyspecific (raised against a mixture of venoms of different species) F(ab')(2) antivenoms have proved to be generally effective. Many preparations are poor for a wide range of reasons often not related to the method of preparation. The main problem associated with them is the high reaction rate in patients caused by complement-mediated anaphylactic reactions. The most significant recent development in immunotherapy has been the production of ovine Fab antivenoms prepared by replacing pepsin digestion with papain digestion. Theoretically, these possess advantages over F(ab')(2) antivenoms, such as a greater volume of distribution and more rapid kinetics. A major disadvantage of Fab antivenoms is, however, their shorter clearance time, which may result in inadequate blood antivenom concentrations for neutralising venom entering the system late from a venom depot at the bite site. Affinity purification of both Fab and F(ab')(2) antivenoms also results in a major increase in specific activity when compared with the original serum source, but this adds greatly to the cost of production, rendering its use prohibitive in the rural tropics where bites and stings are a major problem. The use of sheep as opposed to horses for immunisation also results in a cheaper product, due to the lower cost of animal maintenance; theoretically, sheep preparations should also be safer, causing fewer sensitivity reactions, due to the nature of ovine as opposed to equine protein. Additionally, it is a great advantage in the rural tropics to have a lyophilised, as opposed to a liquid, antivenom because of the longer shelf-life of the former at ambient tropical temperatures. However, lyophilisation does add considerably to the cost of production, involves additional testing and has also in the past been reported to result in some decrease in neutralising potency. There may well be a case for the development of a combined ovine Fab/F(ab')(2) antivenom which combines the advantages of each product. Alternatives to conventional antivenoms should also be explored in the future.

PROXIMATE ANALYSIS, PROTEIN QUALITY AND MICROBIAL COUNTS OF QUICK‐SALTED, FRESHLY MADE AND STORED FISH CAKES

ABSTRACTWith the purpose of evaluating quick‐salted fish cakes as a food, proximate chemical analyses, protein quality (Protein Efficiency Ratio and Net Protein Utilization) and bacterial counts of cakes, freshly made and stored for 18 months at an ambient tropical temperature, were de termmed. The cakes were found to contain an average of 30% protein, 60% salt and 10% moisture. Freshly made cakes were found to be superior, and 18‐month‐old cakes slightly inferior to casein, in both PER and NPU values Finally, total plate and halophilic counts of freshly made cakes, already low (9,000 and 12,000/g, respectively), were found to decrease to ahnost zero after 18 months. Considering present U.S. Recommended Daily Allowances for high quality protein foods, it was calculated that each 450‐g cake, costing $0.44, would be sufficient to cover the daily protein needs of three adults or possibly two adults and two young children. The average daily protein cost for each adult would be $0.15.