Chemical and Microbiological Hazards of Dried Fishes in Bangladesh: A Food Safety Concern

Food safety along with nutrition is an important issue in the present word. Only nutritionally safe food can ensure a healthy balanced diet to consumers. Dried fish is a popular processed fishery product not only in our country, but also in many countries of the world. It is a very good source of dietary protein, lipid and minerals necessary for a healthy body. The consumers of dried fish in national and international level are losing their interest to buy dried fish due to poor quality and safety of the products. Therefore, we reviewed the state of knowledge regarding the contamination level of dried fish by heavy metals, harmful pesticides, amount of lipid oxidation, and microbial quantity and quality from several districts in Bangladesh. The data reviewed in this article revealed that several dried fishes contaminated with excess amount of heavy metals (Pb, Cd, Cr etc.), pesticide residue (dichlorodiphenyltrichloroethane, heptachlor, endrin, aldrin, dieldrin), higher degree of lipid oxidation, excess amount of total plate count and presence of highly pathogenic E. coli, Salmonella sp. Vibrio sp. were found in few dried fish that may cause substantial human health hazard after consumption. The possible factors of these hazards are traditional drying, use of illegal pesticides with higher dose, lack of maintaining proper hygiene, sanitation, packaging, storage, distribution as well as water pollution. These findings will be helpful to develop an effective quality control and assurance program for producing safe dried fishery products for domestic consumption as well as earning foreign currency.

Effect of Waste Bamboo Fiber Addition on Mechanical Properties of Soil

For soil improvement, a method using plant fiber has been used since ancient times. In recent years, the construction method using plant fiber has attracted attention as a ground improvement technology with less environmental load. In this work, the soil improvement effect using waste bamboo fiber was experimentally examined. The liquid limit and plastic limit of the mixed soil tended to increase with increasing bamboo fiber content and there was no change in the plasticity index of the mixed soil by the difference of bamboo fiber content. As a result from the compaction test and unconfined compression test, it was revealed that mixing of bamboo fiber resulted in a reduction of soil material required for construction and increasing in strength. The maximum compressive stress of the bamboo fiber mixed soil at the mixing ratio of 0%, 1%, 3% and 5% were 115, 108, 130 and 152 kN/m2, respectively. As the soil with fiber showed the lower stiffness and higher strength than that without fiber in the dry region, it can be judged that the addition of fiber brought ductility to the soil. And it was found that the decrease in the stiffness of the specimen due to the increase of water content was suppressed by the addition of the bamboo fiber. From the results of the observation with the digital microscope, it was observed that the two-layer structure consisting of the main relatively thick fibrous structure and the secondary capillary fibrous structure were formed. Thus, it was found that the complex structure of the bamboo fiber is deeply involved in the strength of the mixed soil.

Inhibition of citral nanoemulsion to growth,spoilage ability and Al-2/luxS quorum sensing system of Shewanella putrefaciens CN-32:a study on bacteriostasis from in vitro culture and gene expression analysis

Objectives:The bacteriostatic effects of a citral nanoemulsion against Shewanella putrefaciens CN-32(SHP CN-32)were investigated using in vitro culture and gene expression analysis,forbuilding a potential application in spoilage microorganism control and aquatic products quality maintenance.Materials and Methods:SHP CN-32 was treated by prepared citral nanoemulsion when the minimal inhibitory concentration(MIC)was verified.The growth curve,membrane integrity,scanning electron microscope(SEM)observation,biofilm formation and quorum sensing(QS)signaling molecule Al-2 content were evaluated in different MIC treatment groups(0 to 1.00 MIC).The gene expression status of SHP CN-32 in O and 0.50 MIC groups were compared using transcriptome sequencing and quantitative polymerase chain reaction(PCR).Results:The in vitro culture revealed that the citral nanoemulsion could inhibit the growth of SHP CN-32 with MIC of approximately 200μg/mL.Images of membrane integrity.SEM and biofilm formation suggested significant biological structure damage in bacteria after treatment.Meanwhile,the Qs signaling molecule Al-2 content showed a decline with increasing treatment concentration.Transcriptome sequencing and quantitative PCR revealed that the majority genes related diversified functional metabolic pathways of SHP CN-32 were downregulated at varying degree.Conclusion:A significant bacteriostasis of citral nanoemulsion against SHP CN-32 was verified via the results of growth inhibition,structural destruction,signal molecular decrease and gene expression downregulation of strains.These synergies significantly affect the characteristic expression of SHP CN-32,revealing the application potential as bacteriostat,QS inhibitor and preservative in aquatic products.