KR-102961444-B1 - METHOD AND SYSTEM FOR PURGING OFF-FLAVOR COMPOUNDS FROM FARM-RAISED FISH

KR102961444B1KR 102961444 B1KR102961444 B1KR 102961444B1KR-102961444-B1

Abstract

A purification process is employed to remove off-flavor contaminants from fish through an advanced oxidation process. Before harvesting, the fish are transferred to a purification tank or zone that holds water. Off-flavor compounds seep from the fish tissue into the water within the purification tank or zone. The water within the purification tank or zone is circulated through an advanced oxidation reactor that reduces the concentration of off-flavor contaminants in the water through an oxidation process.

Inventors

크롭 램지
배리 테렌스 피.
캡소스 데이비드 더블유.

Assignees

엑시톤 클린, 엘엘씨

Dates

Publication Date: 20260508
Application Date: 20220504
Priority Date: 20211129

Claims (10)

A method for reducing the concentration of geosmin or 2-methylisobornel (MIB) compounds in aquatic organisms grown in a Recirculating Aquaculture System (RAS), and A step of transferring the aquatic organism from the growth zone within the RAS to a purification zone or tank that receives water before harvesting the aquatic organism; Step of stopping feeding the aquatic organisms after they have been transferred to a purification zone or tank; A step of circulating water from a purification zone or tank to a degassing and oxygen treatment unit, degassing the water and supplying oxygen to the water, and then returning the water to the purification zone or tank; A step of circulating water from a purification zone or tank to an advanced oxidation perfusion reactor and through it and then circulating it back to the purification zone or tank, wherein in this process, a water flow is generated in the purification zone or tank; and A step of maintaining a geosmin or MIB gradient between aquatic organisms and water in a purification zone or tank by subjecting water passing through a reactor to an advanced oxidation process that oxidizes geosmin or MIB compounds in the water, wherein the concentration of geosmin or MIB compounds in the water is reduced in this process; The step of maintaining a geosmin or MIB concentration gradient between the aquatic organism and the water in the purification zone or tank is a method that causes the mass transfer of geosmin or MIB compounds from the tissues of the aquatic organism to the water in the purification zone or tank.
In paragraph 1, A method comprising the steps of generating hydroxyl radicals by a reactor and oxidizing a geosmin or MIB compound passing through the reactor.
In paragraph 1, A method comprising a step of photochemically generating hydroxyl radicals that oxidize geosmin or MIB compounds passing through the reactor and reduce their concentration, wherein a UV light source is included in the reactor.
In paragraph 1, A method further comprising the step of injecting an oxidizing agent into water upstream of the reactor.
In paragraph 1, A method comprising the step of using a UV light source and at least one titanium dioxide-based photoelectrode placed in a reactor to generate hydroxyl radicals, and for the hydroxyl radicals to oxidize geosmin or MIB compounds and reduce their concentration.
In paragraph 1, A method comprising the step of using a UV light source and a titanium dioxide catalyst in a reactor to generate hydroxyl radicals, and for the hydroxyl radicals to oxidize geosmin and MIB compounds in water and reduce their concentration.
In paragraph 6, A titanium dioxide catalyst is connected to a first electrode in a reactor, the reactor includes a second electrode, and the method comprises the step of applying a voltage across the first and second electrodes.
A method for oxidizing geosmin or 2-methylisobornel (MIB) compounds in aquatic organisms grown in a Recirculating Aquaculture System (RAS), and A step of transferring the aquatic organism from the growth zone within the RAS to a purification zone or tank that receives water before harvesting the aquatic organism; Step of stopping feeding the aquatic organisms after they have been transferred to a purification zone or tank; A step of circulating water from a purification zone or tank to a degassing and oxygen treatment unit, degassing the water and supplying oxygen to the water, and then returning the water to the purification zone or tank; and The method comprises the step of circulating water from a purification zone or tank to a perforated reactor comprising a UV light source, a first electrode connected to a titanium dioxide catalyst, and a second electrode, and then circulating it back to the purification zone or tank, wherein the method generates a water flow within the purification zone or tank in this process; the method comprises the step of: generating a water flow within the purification zone or tank in this process; and the step comprises: a. A step of oxidizing and reducing geosmin and MIB compounds in water passing through a reactor by a photoelectrocatalytic process, comprising: irradiating a titanium dioxide catalyst with UV light emitted from a UV light source in the reactor; and causing the UV radiation to be absorbed by the titanium dioxide catalyst, thereby generating negatively charged free electrons and positively charged electron holes on the surface of the titanium dioxide catalyst; b. A step of applying voltage across the first and second electrodes; c. A step of contacting geosmin and MIB compounds flowing through a reactor with a titanium dioxide catalyst, which causes oxidation of the geosmin and MIB compounds due to positively charged electron holes on the surface of the titanium dioxide catalyst that attract electrons from the geosmin and MIB compounds; d. A step of reacting positively charged electron-holes with water passing through a reactor to form hydroxyl radicals; and e. a step of reacting hydroxyl radicals generated by a reactor with geosmin and MIB compounds, which reduces the concentration of geosmin and MIB compounds in water through an oxidation process; A method in which a geosmin or MIB concentration gradient is maintained between aquatic organisms and water in a purification zone or tank by oxidizing geosmin and MIB compounds in water passing through a reactor, which in turn leads to the mass transfer of geosmin or MIB from the tissues of aquatic organisms to the water.
In paragraph 8, A method of mixing hydrogen peroxide with water, wherein the hydrogen peroxide reacts with UV light from a UV light source to form additional hydroxyl radicals.
In paragraph 8, A method further comprising the step of injecting an oxidizing agent into water upstream of the reactor.

Description

Method and System for Purging Off-Flavor Compounds from Farm-Raised Fish The present invention relates to a system and process for raising aquatic organisms, and more specifically, to a system and process for purging off-flavor compounds from aquatic organisms. Over the past 50 years, fish farming has grown significantly in the United States and around the world. For example, there are many reasons for this, including the decline in ocean return due to overfishing and the growing awareness of the sustainability of fish farming. One of the challenges commonly faced in fish farms, and particularly in Recirculating Aquaculture System (RAS) fish farming plants, is the tendency of fish to accumulate unpalatable off-flavors that are unacceptable to consumers. Traces of earthy and musty odors create negative consumer perceptions of farmed fish products and often result in economic losses for producers due to rejected fillets and increased time, labor, and capital costs, all of which are related to off-flavor improvement. These off-flavor compounds are primarily geosmin and 2-methylisoborneol (MIB). Many sources of these compounds are present in operating fish farms, including contaminants in influent facility water, bacterial destruction of uneaten food, bacterial destruction of excrement and other livestock by-products and tissues, biofouling on surfaces within growth systems, and bacterial activity within denitrification bioreactors. These off-flavor compounds can be transferred into and out of the tissues of farmed fish, and unless otherwise resolved, they will eventually reach equilibrium with the surrounding water. A process known as purification is employed to reduce the concentration of these off-flavor compounds in the water of purification zones or tanks. One common method to reduce the concentration of off-flavor compounds in fish is to continuously or intermittently dilute the water within the purification zone or tank. The dilution approach to reduce the concentration of off-flavor compounds in fish and other aquatic organisms has many drawbacks and disadvantages. First, a massive amount of water is consumed. Second, this approach to purge off-flavor compounds from fish is time-consuming and therefore costly. Figure 1 is a flowchart illustrating the basic steps or processes involved in purging off-flavor compounds from fish raised in a recirculating aquaculture system (RAS). Figure 2 illustrates an advanced oxidation system for removing off-flavor compounds from fish raised in a RAS. FIG. 3 illustrates a perforated advanced oxidation reactor used in one embodiment of the present invention for reducing the concentration of off-flavor compounds emanating from fish. FIG. 4 is a cross-sectional view of the advanced oxidation reactor shown in FIG. 3 and illustrates a method for monitoring the operation of the advanced oxidation reactor. Figure 5 is a graph of a study illustrating the effectiveness of the advanced oxidation process of the present invention in reducing the concentration of off-flavor compounds (geosmin and MIB) from water. Figure 6 is a practical study illustrating the effectiveness of the advanced oxidation process of the present invention in reducing the concentration of off-flavor compounds in water within a purification tank while fish are actively purified. Figure 7 is a practical study illustrating the effectiveness of the advanced oxidation process of the present invention in reducing the concentration of off-flavor compounds in fish contained in a purification tank. Fish raised in recirculating aquaculture systems (RAS) may accumulate off-flavor organic compounds that adversely affect the flavor and odor profile of the fish meat produced. Two major off-flavor compounds of interest are (1) geosmin and (2) 2-methylisoborneol (MIB). Many sources of these compounds exist in operating fish farms, for example, contaminants in influent facility water, bacterial destruction of uneaten food, bacterial destruction of excrement and other livestock by-products and tissues, biofouling of surfaces in growth systems, and bacterial activity in denitrification bioreactors typically found in RAS. Although known processes attempting to reduce the concentration of these off-flavor compounds exist, most are inefficient. These processes consume large amounts of water, require a long time to reach on-favor conditions, and result in significant biomass loss for the fish. All of these factors affect the marketability and commercial viability of fish farming, and can have negative consequences for environmental issues and the general welfare of the fish. The present invention involves a purification process that overcomes the shortcomings and disadvantages of conventional approaches. The primary objective of the present invention is to provide a purification process that is efficient and designed to prevent or reduce harmful effects on fish. Furthermore, the purification process described herein is designed to