Postharvest Microbiology of Farm-reared, Tropical Freshwater Prawn (Macrobrachium Rosenbergii)

ABSTRACT: The microbiological quality of farm-reared, tropical freshwater prawn ( Macrobrachium rosenbergii ) stored at 2 different temperatures was studied. The prawn muscle was found to have the initial bacterial load of 10⁴ cfu/g. The lactics and vibrios were in the range of 10² cfu/g, while the E. coli , aeromonads, staphylococci, anaerobes, and molds were in the level of 10¹ cfu/g. Salmonella and Vibrio cholerae were present in the prawn muscle. The prawn muscle held at room temperature (28 ± 2 °C) was organoleptically acceptable up to 8 h, when the bacterial load was more than 10⁶ cfu/g. However, the prawn muscle stored at freezer temperatures (−10 to −15 °C) was found to be in acceptable condition even after 30 d of storage and the bacterial load was fluctuating in the range of 10³ to 10⁴ cfu/g.     

Microbiological quality of sous-vide cook chill fish cakes during chilled storage (3 °C)

Fish cakes prepared from emperorbream ( Lethrinus lethrinus ) were vacuum packed (VP), conventionally cook-chilled (CCC) and sous-vide cook-chilled (SVCC) and examined for their microbiological quality and safety during chilled storage (3 °C) for a period of 3, 5 and 16 weeks, respectively, in comparison with conventional pack(CP). The shelf life of CP, VP, CCC and SVCC packs of fish cakes were 2, 2, 4 and 16 weeks, respectively, based on the acceptable break point of the overall sensory scores. The total bacterial counts were 5 log cfu g⁻¹, in CP, VP and CCC packs; and 3 log cfug⁻¹ in SVCC pack on sixteenth week. Total lactic acid bacteria were 2 log cfu g⁻¹ on 2 and 3 weeks in CP and VP, respectively. Staphylococci were detected in all packs on sixteenth week at 2 log cfu g⁻¹. Total bacilli were detected in CP and VP at 3 log cfu g⁻¹ level after 2 weeks. Aeromonads were detected after 1, 2 and 4 weeks in CP, VP and CCC packs at 3 log cfu g⁻¹. Total anaerobic sulphite-reducing clostridia were detected only in CP and CCC packs at 3 MPN counts g⁻¹ level on the final day.     

Stability of chloramphenicol residues in shrimp subjected to heat processing treatments

The stability of chloramphenicol residues in white shrimp (Penaeus indicus) subjected to cooking (100 degrees C) for 10, 20 and 30 min (C1, C2 and C3) as well as retorting (121 degrees C) for 10 and 15 min (R1 and R2) was studied by a microbial assay method using Photobacterium leiognathi as the test organism. The microbial assay method was found to have a good sensitivity of 1 microg/ml the loss of chloramphenicol in shrimp subjected to cooking for 10, 20 and 30 min was 6%, 12% and 29%, respectively. Similarly, the loss was 9% and 16% from the shrimp subjected to retorting for 10 and 15 min, respectively. The loss of chloramphenicol was found to increase with increase in temperature and duration of heating. This study showed that chloramphenicol is an unstable aquaculture drug that is destroyed or degrades during heat processing treatments.     

Dry ice as a novel chilling medium along with water ice for short-term preservation of fish Emperor breams, lethrinus (Lethrinus miniatus)

Emperor breams, lethrinus (Lethrinus miniatus) stored in a combination of dry ice and water ice at an optimum level of 20% and 50% were found to be in excellent condition up to 24 h without reicing. Total bacterial load ranged from 10⁴ to 10⁷ cfu/g, while total psychrophiles from 10² to 10⁴ cfu/g. Total lactics were found in the levels of 10¹ to 10² cfu/g. H₂S producers were detectable only on the 6th hour with a load of 10² cfu/g. Total coliforms and total anaerobic sulphite reducers did not show any consistent trend. TVB-N increased from 11.5 to 21.1 mg%, while TMA-N from 1.3 to 2.7 mg% in samples stored in the combination of dry ice and water ice. TVB-N and TMA-N in the samples stored only in water ice were found to be high. Hypoxanthine varied from 5.1 to 8.2 mg/100 g.     

Numerical and experimental analysis on tensile properties of banana and glass fibers reinforced epoxy composites

Sādhanā - In present day scenario, moving towards an environment friendly material is a key issue for manufacturing industries in order to provide suitable alternatives for the existing...     

An Experimental and Numerical Investigation on the Mechanical Properties of Addition of Wood Flour Fillers in Red Banana Peduncle Fiber Reinforced Polyester Composites

ABSTRACT

In this work, eco-friendly red banana peduncle fiber reinforced polymer composites (RBPF) and wood flour are added as a filler (RBWF) were prepared using compression molding process. These composites were analyzed by testing of properties such as tensile strength, flexural strength, impact strength, and water absorption. Tensile and flexural properties of the composites are verified using ANSYS. The chemical functional group of the composites was analyzed by Fourier transform-infrared spectroscopy (FT-IR). Microscopic examinations were conducted using the scanning electron microscopy (SEM) analysis. Crystallinity index (CI) and Crystalline Size (CS) of the composites were found by conducting X-ray diffraction (XRD) analysis. Results indicated their appropriateness in lightweight applications in automobile, construction and aviation industries.     

Microbiological and biochemical quality of grouper (Epinephelus chlorostigma) stored in dry ice and water ice

The changes in the microbiological and biochemical quality of grouper (Epinephelus chlorostigma) stored in dry ice (solid carbon dioxide) were investigated. Fresh fish stored in dry ice at the ratio of 1:1 (wt/wt) were found to be organoleptically suitable for consumption when they were stored for 30 h without re‐icing. Fish stored in water ice (as control) at the ratio of 1:1 (wt/wt) and in a combination of dry ice and water ice at the ratio of 1:0.2:0.5 (wt/wt/wt) were acceptable up to 18 and 24 h, respectively. Total bacterial load ranged from 10⁵ to 10⁷ CFU g^?1, while total psychrophiles from 10³ to 10⁶ CFU g^?1. Total lactics were found in the levels of 10²–10⁴ CFU g^?1. Total volatile basic nitrogen contents were within the limit of acceptability in all the three treatments, whereas trimethylamine nitrogen content exceeded the limit (15 mg%) and hypoxanthine content was 11.11 mg (100 g)^?1 on the 30 h in grouper stored only in dry ice. Lowest temperature of ?5.8 °C was recorded in grouper stored only in dry ice. Hundred percent CO₂ environment within the package was found in grouper that were stored in dry ice and combination of dry ice and water ice.     

Survival of amine-forming bacteria during the ice storage of fish and shrimp

Survival of amine-forming bacteria during the ice storage of fish and shrimp was investigated up to 14 days of storage. On iced storage the total bacterial load was reduced to one log from an initial load of 10⁵ cfu g⁻¹ in fresh fish/shrimp due to cold shock. The total incidence of biogenic amine-forming bacteria was found to be 74·63% in fish and the same was recorded as 56·05% in shrimp. The amine-forming bacteria recorded were cadaverine- and putrescine-forming bacteria in fish/shrimp, and no histamine former was detected. Gram-negative, non-fermentative rods, viz. Alcaligenes. Flavobacterium, Acinetobacter. Shewanella andPseudomonas , were the predominant amine-forming bacteria during the ice storage of fish and shrimp, in addition to the only Gram-positive genus Micrococcus. The genera Aeromonas and Photobacterium also survived ice storage to a certain extent and may also be responsible for the formation of amines in fish and shrimp.