Aquaponic Tomatoes And Perch: Quality And Nutritional Analysis

While the world population and fish consumption are increasing, the oceanic supply of seafood is decreasing. Although farm-raised fish production has risen to meet the growing demand, these products are often viewed negatively by consumers. Furthermore, greenhouse gas emissions, land use, and water use of fish farms negatively impact the environment. Aquaponics, a food production technique where fish and vegetables are cultivated in the same system, is a more environmentally sustainable strategy to address growing seafood demand.

Abstract

Despite the environmental benefits of aquaponics, relatively little is known about how aquaponic products compare with conventionally produced products. The objective of this study was to compare the composition of products (yellow perch; tomatoes) produced in an aquaponics system versus conventionally produced counterparts.

Perch were sourced from three conditions (aquaponics, wild-caught, pond aquaculture) and measured for size, color, texture, moisture, fat, and protein content. Similarly, aquaponic early girl and cherry tomatoes were compared with soil-grown tomatoes.

The tomatoes were analyzed for weight, color, texture, moisture, acidity, soluble solids, total phenolics, and antioxidant capacity. Across both tomato varieties, the aquaponic tomatoes were moister, firmer, lighter in color, and more yellow than the soil-grown tomatoes. Weight, acidity, and sugar content also varied by production method, but results were not consistent across varieties.

Compared with the pond perch, the aquaponic perch were smaller, lighter in color, and redder. Compared with wild perch, the aquaponic perch were heavier and longer, but less red. The findings from this study provide a foundation for growers and retailers considering aquaponics as an environmentally sustainable alternative to traditional aquaculture.

The understanding physical composition of aquaponic products is necessary to optimize production and consumer acceptance. This data can be used alongside additional sensory and consumer studies to better understand strategies to support the success of aquaponics products.

Introduction

The health benefits of consuming fish have contributed to its rising popularity among consumers over the past few decades. Many people have incorporated fish into their diet in order to obtain essential w-3 fatty acids, which must be supplied through food in order to receive their nutritional benefits.

Fish is also recommended as part of a healthy diet due to its low saturated fat and high protein content. Additionally, fish consumption decreases the risk of cardiovascular diseases, including arrhythmias, heart attack, and stroke.

Although increased fish consumption is beneficial from a health standpoint, it can be concerning from an environmental standpoint as seafood production often has a significant environmental impact. Researchers have found that the source or production method of fish is extremely important when looking at environmental impact.

Due to its popularity among consumers, the ocean’s supply of wild caught fish is depleting at an unsustainable rate. Although traditional aquaculture, or farm raised fish, aim to address this issue, these products actually cause additional harm to the environment. Traditional aquaculture is land and water intensive which puts a strain on the supply of available natural resources.

If released into the natural environment, the waste water produced by fish farms has the potential to be toxic to the surrounding ecosystem. The lack of sustainable aquaculture is of great concern given the world’s population is expected to continue increasing at a historically steep pace over the coming years. By the year 2050, it is projected that a 60% increase in global food production will be needed in order to provide for the growing population.

The potential challenge to feed the growing population depends not only on population growth, but also on technological advancements and sustainable practices. A sustainable food production method that uses fewer natural resources will be necessary in order to continue providing the population with healthful food choices.

Aquaponics is one alternative food production method that could help alleviate the concerns associated with unsustainable aquaculture. Aquaponics can be described as the combination of hydroponically grown plants and a recirculating aquaculture system. A more specific type of aquaponics system is integrated multitrophic aquaculture (IMTA).

IMTA systems are closed loop systems which allows the plants, fish, shrimp or other detritivorous shellfish, and bacteria to live off of each other in an ecosystem manner. One aspect of aquaponics, or IMTA, that differentiates it from other sustainable growing techniques, such as conventional hydroponics, is that aquaponics does not require the use of fertilizers for plant growth.

The system is set up in a way that allows the wastewater from the fish, which is rich in nutrients, to be circulated to the bacteria source. The bacteria then utilize the nitrogen in the fish waste by converting it into nitrite, which is then circulated to the plants in the system. The plants take advantage of the nitrites and nutrients in the water and use them as a natural food source, thus cleaning the water and recirculating it back to the fish to be reused.

Both the health benefits and the quality of a product are of high concern to consumers when purchasing fish. One study conducted by Conte, et al. determined that when choosing between farmed fished or wild caught fish, consumers were more likely to choose the option that they perceived as healthier and as being a higher quality product. Although aquaponics has the potential to alleviate food production concerns, current aquaponic literature is limited to comparisons of aquaponic plant growth to hydroponic methods or a comparison of certain types of aquaponic growing methods.

In order to successfully promote aquaponics to both consumers and producers, it is important to ensure that the nutritional and quality characteristics of aquaponic products are equal to, if not better than, conventionally grown products.

Review of Literature

Sustainability of Aquaponic Systems

Aquaponics is one of the most efficient and sustainable production systems of consumable animal protein. One variant of aquaponics is integrated multitrophic aquaculture (IMTA). What differentiates IMTA aquaponics from traditional aquaculture and hydroponics systems is its ability to produce three profitable, and typically consumable, products from one enclosed system.

Not only is IMTA able to yield multiple products, but it also does so while conserving resources. IMTA aquaponics utilizes an ecosystem approach in which the water continuously recirculates throughout the entire system, therefore decreasing water usage. Their ability to operate under low water input allows IMTA systems to be successful in areas that lack access to water, such as deserts or urban settings, and therefore decrease land usage.

In addition to recycling water, integrated aquaponics also recycles various other materials, such as uneaten fish feed, which are typically a byproduct of traditional aquaculture systems. In IMTA systems, uneaten fish feed is repurposed as valuable biomass and recirculated throughout the system. Recirculating waste throughout the system allows for it to be used for growth by other organisms and plants rather than being expelled from the system as potentially toxic solid waste.

According to Lennard, the plants in aquaponics systems can receive up to 80% of the nutrients required for their optimal growth from fish waste alone. The ability of recirculating fish waste to provide plants and detritivores with essential nutrients decreases the need for additional mineral supplementation in IMTA systems. The sustainability of IMTA aquaponics makes it an attractive solution to the increased need for consumable seafood.

Impact of Production Method on Quality and Nutrition of Fish

One concern when utilizing innovative food production systems is whether or not the physiochemical and nutritional parameters of the product will be affected. This concern has been historically relevant regarding farm-raised fish compared to wild-caught fish.

Freshness, quality, nutritional value, and healthiness are all of importance to consumers when choosing what fish to consume. However, the research regarding whether or not the production method impacts fish quality and nutrition are rather mixed. The lipid profile of fish is a nutritional parameter that is of high importance to consumers.

Some researchers suggest that wild-caught fish have a more rich lipid profile, while others would argue that farm-raised fish are a better source of healthy fat. Furthermore, other data show no difference in the overall fat content of farm-raised versus wild-caught fish.

Protein is another important nutrition indicator of fish in which the research regarding differences based on production method is mixed. Both Verbeke, et al. and Manthey-Karl, et al. determining protein levels in farmed fish to be similar to those of wild-caught fish. Contrastingly, Alam, et al., Fuentes et, al., and González, et al. determined wild-caught fish to be a higher source of protein than farm-raised fish.

The quality characteristics of fish that are of importance to consumers typically include appropriate color depending on species, firm texture, and high moisture content. Similar to the nutritional indicators, the research regarding the variation of quality indicators between fish production methods is mixed. Differences have been found between wild and farm-raised fish in terms of color, texture, and moisture content. The comparison data of wild-caught and farmed raised fish supports the possibility of quality and nutrition characteristics varying by production method.

The data comparing farmed and wild-caught fish is also an example of how a similar comparison is needed regarding aquaponics products. As shown between farm-raised and wild-caught fish, production methods can impact both nutrition and quality indicators of fish. Being that both nutrition and quality indicators significantly impact product acceptance, it is crucial to determine what impact, if any, the production method of aquaponics has on its products.

Impact of Production Method on Quality and Nutrition of Produce

Similar to the comparison of wild-caught and farm-raised fish, researchers have investigated the impact of various growing methods on produce. Chandra, et al. sought to determine if growing produce using aeroponics, the process of spraying nutrient-rich water on the roots of suspended plants, is as effective as growing the same products using conventional techniques.

Chandra et al. determined that aeroponics produces a higher yield of produce compared to conventional soil methods. The comparison of aeroponic products to soil-grown products revealed that the aeroponic products had higher levels of phenolics, antioxidants, and flavonoids.

Similar to Chandra, et al., Rodríguez-Ortega, et al. compared the impact of various soilless growing systems on tomatoes. Their study determined that the mineral composition, and therefore nutrition content, of the tomatoes, varied between different soilless growing methods.

In regards to the impact of aquaponics, Suhl et al. analyzed the physical components of aquaponic tomatoes and hydroponic tomatoes in order to compare the quality of the products. Researchers found that the level of soluble solids content and the sugar-acid ratio were both significantly increased in the hydroponic tomatoes which is important because overall fruit flavor is highly affected by both soluble solids and sugar-acid ratio.

Other researchers, such as Maucieri, et al. have assessed the impact of closed system variables, such as fish stocking densities, on the quality of aquaponic products. Although studies, such as those completed by Suhl, et al. and Maucieri, et al., are valuable, the overall research on aquaponic products is limited.

Due to the evidence that the growing method can alter product outcomes, research that compares aquaponic products to conventionally grown products needs to be conducted. Specifically, the physical and nutritional components of aquaponic products need to be compared to conventionally grown products.

Impact of Production Method on Sensory Acceptance

Similar to how the production method can impact the quality and nutrition of products, it is important to determine if the production method impacts the consumer acceptance of products, as well. Several studies have compared the sensory acceptance of various types of farmed and wild-caught fish including cod, salmon, and flounder.

These studies have not found significant differences between farmed and wild-caught fish in terms of sensory characteristics. The studies have determined farmed fish to be equally as accepted by consumers as wild-caught fish. However, some of these studies were held under a blind condition which could have an effect on study outcomes.

Similar results have been found when investigating the effect of the production method on the acceptance of tomatoes. Ercilla-Montserrat, et al. examined the quality and acceptance of tomatoes grown in a rooftop hydroponic system.

During the sensory study, consumers were asked to consider the appearance, texture, ripeness, size, and taste of rooftop products. Despite the rooftop production system being obscure to the participants, 77% of participants rated the product as good or very good, and 65% of participants rated the texture of the tomatoes as good or very good. However, the study did not analyze the rooftop tomatoes against control, which would have strengthened the study’s finding.

Sensory studies are helpful in determining whether consumers accept products, especially those of various production methods. In order to strengthen the data collected in sensory studies, it would be beneficial to provide participants with quantitative data that describe the products they are sampling.

Specifically, providing participants with quantitative quality and nutrition data during a sensory study could help to better evaluate the consumer acceptance of products. Similar to the rooftop system that was examined in the study of Ercilla-Montserrat, et al., aquaponics is a food production system that consumers may not be familiar with.

The negative impacts that unfamiliarity can have on consumer acceptance could be controlled by ensuring participants that the products are of good quality and nutrition as evidenced by data. Further research regarding the quality and nutrition indicators of aquaponic products is needed.

Impact of Production Method on Consumer Acceptance

Consumer attitudes can also vary based on the production method of products. Consumer willingness to pay for a product is one way to measure consumer attitudes related to a product, as consumers are likely to pay more for a product that they are accepting of. American consumers have expressed a willingness to pay more for aquaponic produce compared to soil-grown produce.

However, not all research regarding the willingness to pay for products grown using innovative techniques reflects this finding. Others have found that utilizing innovative food production methods does not increase the price that consumers are willing to pay for a product compared to conventionally prepared products.

The current research regarding consumer willingness to pay for aquaponic products is mixed. Expanded research regarding the quality and nutrition parameters of aquaponic products could be useful in measuring willingness to pay in the future. Providing data to participants that support the nutrition and quality components of aquaponic products could help to increase willingness to pay towards aquaponic products.

Milicic, et al. found that the general attitude towards aquaponics in European consumers is overall positive. After being presented with information regarding the innovative and sustainable aspects of aquaponics, participants reported an overall positive attitude towards aquaponics.

Although positive attitudes were more frequent, consumers also expressed negative attitudes towards aquaponics despite a positive explanation of the production system being given to them prior to completion of the survey. The negative attitudes towards aquaponics were categorized into three groups: negative emotions related to the disgust of the connection between fish excrements and vegetables, negative perceptions of animal welfare in aquaponics, and general distrust of positive claims about aquaponics.

The reasoning behind negative attitudes towards aquaponics is not surprising considering aquaponics is a unique and relatively new production method that consumers are not familiar with. Additional research could be beneficial for improving consumer attitudes towards aquaponics.

Determining how aquaponic products compare to conventionally grown products in terms of nutrition and overall quality could help improve consumer attitudes towards aquaponics. Assurance that aquaponics produces products of equal or greater nutrition and quality compared to what consumers are used to could help improve consumer attitudes towards aquaponic products.

Similarly, to consumer attitudes, consumer perception towards products can vary based on production method. Often times consumers already have a certain perception of a product that is based exclusively on their preexisting thoughts and attitudes.

An example of this can be seen in a Belgian study in which consumers expressed the belief that wild-caught fish would taste better than farm-raised fish despite having not sampled either of the products. Furthermore, when questioned about the nutritional value of farmed fish versus wild-caught fish, participants elected that wild-caught fish would have a more nutritious profile than farm-raised fish.

These findings support the idea that consumers often have a perceived attitude towards a product prior to consuming the product.

Additional research is needed to determine the quality and nutrition indicators of aquaponic products in order to prevent premature perceptions from being made about aquaponic products. Assuring that aquaponic products are of equal to or greater quality and nutrition compared to conventionally grown products will reduce negative perceptions that could be made about aquaponics.

Aquaponics is a potentially sustainable solution to the increased need for consumable seafood. Its ecosystem approach allows aquaponic systems to produce three products while using less land, water, and materials than traditional aquaculture. Aquaponics also decreases the risk of toxic waste from entering the surrounding environment due to its ability to recirculate and repurpose waste throughout the system.

However, current aquaponics literature is limited and does not address crucial concerns related to it being a new, innovative production method. Research needs to determine if aquaponic products are of comparable quality and nutrition in reference to conventionally grown products. This current study aims to address that research need.

Conclusion

The need for sustainable seafood production in order to meet the needs of a growing population while maintaining the environment’s integrity is evident. While aquaponics offers a solution to this problem, research regarding this food production system is limited.

In order for aquaponics to be widely accepted by consumers and incorporated by producers, research needs to determine how the quality and nutrition indicators of aquaponic products compare to conventionally grown products. This current study aimed to address that need.

This study successfully compared two aquaponic products to their conventionally grown counterparts in terms of both quality and nutrition. It was determined that the AP weighed less than the PP but more than the WP. The AP was also shorter than the PP. The AP was lighter than the PP and less red than the WP.

No differences were found in fat or protein content. The aquaponic EG weighed more than the soil EG, while the aquaponic SRH weighed less than the soil SRH. Both varieties of aquaponic tomatoes were firmer than their comparisons. The aquaponic SHR also had stronger skin compared to the FM cherry variety, and a higher moisture content compared to the soil SRH.

The aquaponic EG was lighter and more yellow than the soil EG, while the aquaponic SRH was lighter than both the soil and FM comparisons. The aquaponic EG was less acidic than the soil EG, and the aquaponic SRH was more acidic than the FM cherry tomatoes. Sugar content was lower in the aquaponic EG compared to the soil EG. The aquaponic SRH had a higher sugar content than the FM cherry tomatoes, but a lower sugar content than the soil SRH. No differences were found in phenolics or antioxidants.

The analysis of both plants and fish from an aquaponics system is significant as previous research is limited in both of these areas. Variation in quality indicators between aquaponic products and conventionally grown products was found. Some of the variations were favorable towards aquaponics, such as that regarding tomato firmness and moisture. Other differences suggest that there is room for improvement in aquaponic products, such as in the skin strength or sweetness of tomatoes.

More so, the majority of the data collected in this study support aquaponics as being at least equal to conventionally grown products in terms of quality and nutrition indicators.

This data can be useful to a wide audience. Producers could use this data to help them decide if aquaponics is a production method that they would like to utilize. Producers can also use these findings to identify areas in which aquaponic systems could improve.

In addition to producers, consumers can also benefit from these research findings. Being a new, innovative food production system, consumer exposure and knowledge regarding aquaponics may be limited at this time. The data gathered in this research study can be used to help consumers become familiar with aquaponics while being assured that aquaponic products are of equal quality to conventionally grown, familiar products.

A large audience that can utilize these findings is fellow researchers. This study helps to fill literature gaps that exist regarding aquaponics. However, additional research is still needed. One area of future research that is crucial in regard to the success of aquaponics is a sensory study that compares the acceptance of aquaponic products to conventionally grown products.

As stated before, this current study provides quantitative data on the quality and nutrition indicators of aquaponic products. This quantitative data could be strengthened by the presence of qualitative data. Qualitative data from a sensory study would help to solidify the claim that aquaponic products are of equal quality to conventionally grown products.

Aquaponics has the potential to help alleviate the current stress being put on the oceanic supply of seafood by providing a sustainable alternative to feed the world’s growing population. This research study helps to encourage the use of aquaponic systems by ensuring that aquaponic products are of equal quality and nutrition to conventionally grown products.

Source: Kralik, B. A. (2021). Quality and Nutritional Analysis of Aquaponic Tomatoes and Perch (Doctoral dissertation, Bowling Green State University).

Useful Article: Aquaponics And Urban Horticulture Are Key Aspects Of Circular Economy Sustainability

Comments (2)

  1. Donna Ross August 26, 2021

Leave a Comment!