Quality assessment and shelf-life of processed tilapia (Oreochromis niloticus) fish sticks: Laboratory based study

Customers prefer tilapia (Oreochromis niloticus), one of the most popular freshwater fish species farmed in Bangladesh, because of its flavor and affordable market pricing. This study aimed to develop value-added tilapia fish sticks and evaluate the quality changes, shelf life, and storage stability of the developed tilapia fish sticks in order to investigate the possibilities of better utilizing low-value tilapia fish and to satisfy consumers' growing demand for quality ready-to-eat food products. For this regard, storage characteristics in room (28ºC) and refrigerator (5ºC) temperatures were assessed in terms of microbiological, chemical, proximate, and sensory attributes. The moisture, lipid, protein, and ash contents of the fish sticks were observed to be 56.23±0.62, 7.62±0.27, 26.01±0.39, and 2.93±0.23%, respectively, at fresh condition. As storage time increased, it was discovered that ash content at room temperature increased while moisture, lipid, and protein levels steadily declined. On the other hand, it was discovered that at refrigeration temperatures, ash and fat content increased while moisture and protein content decreased. Compared to fish sticks held at ambient temperature, changes in the proximate composition of fish sticks stored in a refrigerator were found to be more stable. TVB-N was initially measured as 12.38±0.45 mg/100 g. After 24 hours of room storage, the TVB-N value exceeded the acceptable level; however, after 72 hours of refrigeration, it did not exceed the acceptable limit and was deemed fit for consumption. TPC was observed in fresh fish sticks as 3.74±0.31 Log CFU/g. In 48 hours at room temperature, the bacterial load of tilapia fish sticks increased sharply (p<0.05) during the course of the storage period and went above the microbiological threshold for fishery products (7 Log CFU/g of flesh). The bacterial growth trend was slower and, after 72 hours, was within the permitted limit at refrigerated storage temperature. All fresh products had the highest initial sensory ratings. At ambient temperature, all of the products sensory qualities significantly declined with time (p<0.05), however at refrigeration temperature, the product was determined to be more stable. The overall acceptability score assessed for appearance, flavor, taste, and texture was within acceptable limits for up to 24 hours at room temperature, but not for 72 hours at refrigeration temperature. According to the study's findings, tilapia fish sticks have a very limited shelf life at room temperature (28°C), only lasting around 24 hours, whereas they can last up to 72 hours at 5°C in the refrigerator

Assessment of heavy metals concentration in water and Tengra fish (Mystus vittatus) of Surma River in Sylhet region of Bangladesh

The study was carried out to assess the concentration of heavy metals in water and Tengra fish (Mystus vittatus) of the Surma River, the largest water basin ecosystem covering the north-eastern parts of Bangladesh. Water and Tengra fish (M. vittatus) samples were collected from a total of six sampling stations in which three sampling stations were in Sylhet district and the rest three were in Sunamganj district. Samples were collected from February 2017 to June 2017 on a monthly basis. Water and Tengra fish (M. vittatus) samples were analyzed for the detection of heavy metals viz., lead (Pb), chromium (Cr) and cadmium (Cd) concentrations. Atomic absorption spectrophotometry was used for the detection of heavy metals after digestion of the samples. Pb and Cr were detected from both water and Tengra fish (M. vittatus) samples collected from all the six sampling stations of Sylhet and Sunamganj district. But, Cd was not found both in water and Tengra fish (M. vittatus) during the study period. This study concluded that the detected concentrations of metals (Pb and Cr) in the studied Tengra fish (M. vittatus) muscles were accepted by the international legislation limits and are safe for human consumption. But in water, Pb is the only metal that potentially poses the ecological risk to the water body as it exceeds the acceptance level recommended by World Health Organization (WHO). Consequently, close monitoring of metals pollution of the Surma River is recommended with a view to minimizing the health risk of the population that depend on the river for their water and fish supply

An Improved Degree Based Condition for Hamiltonian Cycles

A Hamiltonian cycle is a closed path through all the vertices of a graph. Since discovering whether a graph has a Hamiltonian path or a Hamiltonian cycle are both NP-complete problems, researchers concentrated on formulating sufficient conditions that ensure Hamiltonicity of a graph. A recent paper [Rahman M. Sohel and Kaykobad M., “On Hamiltonian Cycles and Hamiltonian Paths”, Information Processing Letters 94(2005), 37-51] presents distance based sufficient conditions for the existence of a Hamiltonian path. In this paper we establish that the same condition forces Hamiltonian cycle to be present excepting for the case where end points of a Hamiltonian path is at a distance greater than 2

Thinking out of the ‘Man box’: An intersectional exploration of gender dynamics in northern Bangladesh via gender tracking framework

Placing people on boxes and drawing gender lines based upon the social codes of education tend to result in long-term gender inequality in the global context, and in this regard, Bangladesh is not an exception. Our study is an endeavor to explore how both men and women have socialized themselves with the underlying principles of the ‘Man box’ and how such socialization translates into social infanticide of womenfolk in northern Bangladesh. A wide range of qualitative research tools was employed to collect primary data from two regions of northern Bangladesh. Accordingly, we combined three key concepts ‘Man box’, women's subordination, and intersectionality to capture the gender nuances and degrees as well as to unravel the subsequent repercussions on gender dynamics using an author-modified ‘Gender Tracking Framework’. The study noticed that the social education system in northern Bangladesh is largely shaped and driven by deep-rooted ‘Man box’ codes resulting in high levels of gender disparity concerning property rights, workload, wage rate, control over earnings, decision autonomy, social mobility, market participation, power, agency, and voice against violence. Moreover, the intersectional analysis unveiled the multilayered powerlessness of marginalized groups, stemming from their intersecting identities and exacerbated by governance leakage. Their resulting miseries reached to such an ultimate position that even hope seemed like a luxury to them. The findings suggest that gender equality in Bangladesh can only be attained in its true sense through collective socio-cultural transformation by breaking the ‘Man box’ trap and by familiarizing a social education system in which each individual will be taught to treat others equitably without any form of biases, which we termed as ‘Human box’ ideology

Experimental and numerical investigations on the effect of a novel internal surface micro grooving towards improving convective heat transfer performance of tube heat exchangers

In the present work, the use of the passive heat transfer enhancement technique through surface alteration was explored. The enhancement was achieved through internal conduit surface microgrooving using a new apparatus that was developed by modifying a Magnetic Abrasive Finishing technique. A new surface profile was created and later verified using optical and laser profiler measurement. The new profile was investigated numerically to compare the heat transfer and hydrodynamic performance against other profiles that have been studied in the literature. It was found from the results that the new profile shows much higher heat transfer improvement and comparable pressure loss to the previously investigated profiles (i.e. square, rectangular, trapezoidal and circular). Overall, the new groove geometry provides the highest performance followed by the circular, triangular, curvy, square and rectangular grooves. Also, the results indicate that designs with a smooth profile performs better than those with sharp edges, owing to the elimination of stationary fluid spots within the grooves. The effectiveness between the profiles was compared based on the level of heat transfer enhancement against the flow penalty. Experimental validation was further conducted for the experimentally generated groove. The results revealed that a relatively small surface temperature drop was obtained, corresponding to a slight improvement in heat transfer. This confirms the results generated by the simulation that groove size plays a major role in attaining significant improvement in heat transfe