Alex Augusto Gonçalves

Ozone Application in Recirculating Aquaculture System: An Overview

In recirculating aquaculture systems (RAS), particulates (including feces, uneaten feed, bacteria, and algae) can cause several problems, in that they may harbor pathogens, can physically irritate the fish, and upon decomposition, release ammonia and consume oxygen. Mechanical filters, foam fractionators, and other engineered devices are used to remove particles quickly from aquaculture systems, in order to improve fish health and decrease the load on biofilters and oxygenators. Ozone is used in RAS as a disinfectant, to remove organic carbon, and also to remove turbidity, algae, color, odor and taste. Ozone can effectively inactivate a range of bacterial, viral, fungal and protozoan fish pathogens. But the effectiveness of ozone treatment depends on ozone concentration, length of ozone exposure (contact time), pathogen loads and levels of organic matter. In spite of ozone is a very effective oxidizing agent, higher ozone concentrations are a risk to cultured fish stocks causing gross tissue damage and stock mortalities, and also are a risk to bacterial films on the biofilter.

Ozone: an emerging technology for the seafood industry

ABSTRACT In recent years, increasing attention has been focused on the safety of foods, and in particular on the intervention methods to reduce and eliminate human pathogens from fresh product, especially fresh seafood. Traditional technology utilizes water with or without a sanitizing agent to wash fresh seafood. Chlorine is the most widely used sanitizing agent available for fresh product, but it has a limited effect in killing bacteria on seafood surfaces. An alternative treatment is being sought to improve food safety. Many research and industrial trials are underway to validate the use of ozone in the food industry. This article intends to show a clean technology to be applied in seafood industry and to show that many studies must be done to demonstrate the best concentrations and the best methods of ozone applications in diverse seafood species, so that the governments of all the countries can approve their application in the fishing industry. Key words : Clean technology, ozone, seafood

Restructured fish product from white croacker (Micropogonias furnieri) mince using microbial transglutaminas

This study aimed at determining the influence of three concentrations of commercial transglutaminase enzyme in restructured fillet of minced fish from white croacker (Micropogonias furnieri), one of the four marine species with notability in Brazil. The restructured fillet developed had advantages when compared to traditional fillet, such as absence of spine and less flavour intensity (washes cycles). Washing process for white croacker mince was compared with five clarification agents: water (control), phosphoric acid (H3PO4), sodium chloride (NaCl), calcium carbonate (CaCO3) and sodium bicarbonate (NaHCO3). The higher quality product (whiteness) was obtained with calcium carbonate washes. Three concentrations (1.5, 1.0 and 0.5%) of microbial transglutaminase MGTase (Active TG-B %v/v and Active TG-BP %w/w) were compared, in order to produce fish restructured product (boneless fillet). The concentration of 1.5% (both enzymes), produced better results. The restructured products were compared by sensory analysis and showed better sensory parameters (appearance, odour, flavour and texture) samples treated with Active TG-B (solution form).

Oxygen release compound as a chemical treatment for nutrient rich estuary sediments and water.

The objectives of this work were: (i) to evaluate the efficacy of Oxygen Release Compound (ORC®), oxygen providing agent that enhance the oxidation of organic matter in fresh water, marine water, and sediment; and (ii) to explore the potential aquatic toxicity that might be generated due to its use. A bench scale laboratory experiments were conducted using five different water sources (2 freshwater, 2 marine water and a deionised water). During the assay, flasks of 1 L capacity were dosed with artificial sediment and ORC® and kept at room temperature for 10 days. Temperature, pH, DO, UV254, TOC and Mg were periodically measured. The potential aquatic toxicity that might be generated as a by-product of ORC® use was performed. The experimental results reveal that ORC® is indeed effective in releasing oxygen over a long period of time and it is also effective for the remediation of natural waters enriched with organic matter. The toxicity test shows that ORC® treatment did not create any biological toxicity in freshwater samples (IC50 < 1 Toxicity Unit – TU). However, marine water samples reveal a high toxicity and had IC50 > 1 TU. The study proves that ORC® was an appropriate technology that can safely be used to treat natural waters enriched with nutrient and natural organic matter.

Physicochemical characterization of Atlantic Canadian seafood processing plant effluent

The purpose of this study was to conduct a preliminary assessment of the potential impacts of Atlantic Canadian seafood processing effluents on the aquatic environment through physical-chemical characterization. Shellfish and finfish effluent samples were collected and characterized by biochemical oxygen demand (BOD5), chemical oxygen demand (COD), turbidity, total suspended solids (TSS), ammonia nitrogen (NH3-N), adsorbable organic halides (AOX), soluble BOD5 and soluble COD. Effluent concentration ranges were BOD5 (179 to 276mgL-1), COD (458 to 1717mgL-1), turbidity (28.8 to 88.3NTU), TSS (27.2 to 120.1mgL-1), NH3-N (1.5 to 12.9mgL-1) and AOX (3.2 and 0.4mgL-1) for flatfish and salmon processing effluents respectively, and cleanup shift AOX (3.5 and 0.5mgL-1). The characteristics of these effluents assessed have the potential to contaminate and degrade receiving water body environments. Improved performance may be possible with further treatment technology optimization on an effluent-specific basis.

Toxicology evaluation of Atlantic Canadian seafood processing plant effluent.

The purpose of this study was to carry out an acute aquatic toxicity assessment on select effluent samples from Atlantic Canadian seafood processing plants. Raw effluent acute aquatic toxicity for the flatfish and salmon effluents was assessed using the acute lethality test and Microtox™ test. The effectiveness of dissolved air flotation treatment (DAF) in removing acute toxicity from these effluents was evaluated using the Microtox™ test. The salmon effluent failed the acute lethality test using rainbow trout while the flatfish effluent showed acute toxicity in the Microtox™ test with a 50% inhibiting concentration (IC50) of 38.84%. Subsequent treatment by DAF of the flatfish and salmon effluents increased IC50 values by 20% and 26% respectively. The findings of this study indicate that all of the processing effluents sampled showed characteristics that could potentially degrade effluent receiving waters and acute toxicity was demonstrated in the two raw finfish effluents. Application of DAF treatment was successful in significantly increasing Microtox™ IC50 values, thereby reducing acute toxicity, but failed to entirely remove acute toxicity.

Consumer's perception of food packing: Trends

Este trabalho apresenta uma revisao sobre o setor de embalagens alimenticias no Brasil. Sabe-se que simples mudancas nos habitos dos consumidores e nas decisoes de compras provocam grandes abalos no mercado de embalagens. A habilidade das empresas em perceber essas mudancas torna-se cada vez mais importante. A exigencia do consumidor e por embalagens mais funcionais, e com informacoes claras e objetivas. Diante de um mercado consumidor cada vez mais exigente, a busca pela “embalagem ideal”, que atenda as necessidades do produto como conter, proteger e transportar, alem de conservar, expor e vender passou a ser um desafio para profissionais de diferentes areas. Para que a concepcao da embalagem seja a mais proxima do ideal, alem de atender as exigencias previstas por lei, e preciso considerar os aspectos esteticos e ergonomicos, com o menor custo possivel. Percebe-se, neste estudo, que existe uma certa preocupacao com a conservacao dos recursos naturais e minimizacao de impactos ambientais, atraves do uso de embalagens ecologicamente corretas. Palavras-chave: embalagem de alimentos, tendencias, design e ergonomia.

Seawater ozonation: effects of seawater parameters on oxidant loading rates, residual toxicity, and total residual oxidants/by-products reduction during storage time

ABSTRACT The efficacy of ozonation in different seawater conditions provides an improvement in the water quality and promotes the increment of dissolved oxygen. By-products (bromine, bromate, and bromoform) formation is directly proportional to the ozonation time. Ozone-produced oxidants remain toxic in both closed and dark containers for at least 4 days; however, during long storage period (35 days) in dark and cold conditions, these residual oxidants decrease slowly. These results have practical implications for both the installation of ozone systems on ships ballast water or for recirculating aquaculture system for inactivating undesirable organisms present in seawater.

Acerola Fruit as a Possible Antimelanotic Agent in White Shrimp (Litopenaeus vannamei)

This study aimed to testify acerola’s inhibitory activity on melanosis in farmed white shrimp (L. vannamei). Shrimp samples underwent immersion in different treatments (control group (C), metabisulphite solution group (M), and acerola solution group (A)). Quality Index Method (QIM) was used to measure the shrimp shelf life, during 21 days, where microbiological, chemical, and sensory analyses were performed at each 3 days. Groups C and A exceeded the limit of mesophilic bacterial count within 15 days of storage, and for M the period was 18 days. As for the psychrophilic bacteria, C and A both crossed the limit on day 12 and M on the 15th day. Group M had the highest TVBN and pH means, followed by A and lastly C. Yet, TMA analysis showed highest values in group C, second A, and finally M. Sensory analysis determined the shelf life of groups C, M, and A as 10.5, 14.6, and 12.3 days, respectively. There were not many significant differences between the groups in all analyses; hence, dipping shrimp in acerola solutions would not suffice to inhibit melanosis formation. Further studies are needed to fully determine acerola’s antimelanosic potential.

Evaluation of treatment options for Atlantic Canadian seafood processing plant effluentA paper submitted to the Journal of Environmental Engineering and Science.

The purpose of this study was to evaluate different effluent treatment options for Atlantic Canadian seafood processing plants. Bench-scale testing with a 25-mesh screen, sedimentation (SED), and dissolved air flotation (DAF) was conducted. Treatment by SED and DAF was successful in reducing contaminant concentrations with maximum observed percent reductions: biochemical oxygen demand, BOD5 (90%); chemical oxygen demand, COD (60%); turbidity (99%); total suspended solids, TSS (95%); and ammonia nitrogen, NH3-N (50%). Bench-scale 25-mesh screen runs for select effluent types showed poor reduction efficiencies and appeared to provide inadequate removal of contaminants. Sedimentation and DAF using alum were effective at removing solids but less effective at removing soluble effluent components. Improved performance may be possible with further treatment technology optimization on an effluent specific basis.