Progress 09/15/05 to 09/14/07
Outputs
OUTPUTS: 1. Experiments were performed to further investigate the effect injected proteins from tilapia and catfish have on muscle structure, quality and shelf life 2. Outcomes of this research were presented to industry representatives and also at international conferences 3. Outcomes of this research was tested at select food processors, and was shown to provide significant value addition 4. Results were disseminated to industry by presentations and in-house demonstrations, nationally and internationally. 5. Results were disseminated to industry and academia by presentations at international conferences PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Fish and meat processing companies, food science researchers PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Proteins extracted with the acid and alkaline aided process were further investigated for changes in conformation and functionality. Different levels of unfolding and refolding resulted in functionality changes, which in turn resulted in changes in performance after incorporation into fish fillets. Fillets injected and tumbled with various protein suspensions (made from protein isolates produced with an alkaline-aided pH shift process) were analyzed for microbial stability, oxidative stability, color and muscle cohesiveness. Protein extraction with the alkaline process significantly reduced total aerobic bacteria counts and produced protein suspensions of low microbial counts. Protein injected fillets had equal microbial shelf life compared to uninjected fillets. Color of protein injected fillets was highly comparable to uninjected fillets, and was more natural compared to salt and phosphate injected fillets based on L*, a* and b* values. Fillets injected with protein suspensions had equal to higher oxidative stability than untreated fillets, based on analysis of secondary oxidation products. Fillets injected with protein suspensions were more cohesive than untreated fillets, based on Instron testing. This project is expected to not only lead to better utilization of seafood byproducts, but also lead to the development of fish proteins as commercial and competitive ingredients for water control in seafood products and quality improvement of seafood products. Improvements in water-holding capacity should lead to improvements of US seafood products since products will be more palatable as well as more nutritious since more nutrients are retained as less water is lost. Furthermore more retained water in seafood product is expected to significantly improve the bottom line of the seafood processors and make them more competitive on not only a local but global scale.
Publications
- 1. Hussain, S and Kristinsson, H.G. 2007. Effect of tilapia protein isolate on water-holding capacity and quality of tilapia fillets.IFT Annual Meeting 2007, Chicago, IL. Abstract/Presentation 003-11.
- 2. Raghavan, S and Kristinsson, H.G. 2007. Conformational changes in catfish myosin due to acid unfolding and refolding. IFT Annual Meeting 2007, Chicago, IL. Abstract/Presentation 007-01. (50%)
- 3. Raghavan, S and Kristinsson, H.G. 2007. Conformational changes in catfish myosin due to alkali unfolding and refolding.IFT Annual Meeting 2007, Chicago, IL. Abstract/Presentation 003-12. (50%)
- 4. Davenport M.P. and Kristinsson, H.G. 2007. Changes in conformation and structural stability of catfish muscle proteins after pH-shift processing. IFT Annual Meeting 2007, Chicago, IL. Abstract/Presentation 094-02. (50%)
- 5. Kristinsson, H. G., Theodore, A. E., Petty, H. T., and Raghavan, S. 2006. Bioactive properties of protein hydrolysates products from channel catfish protein isolate. Second Joint Trans-Atlantic Fisheries Technology Conference TAFT 2006. October 29-November 1, Quebec, Canada. (25%)
- 6. Kristinsson, H. G. and Ingadottir, B. 2007. Gelation of protein isolates extracted from tilapia muscle. J. Food Sci. Under review.
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Progress 09/15/05 to 09/15/06
Outputs
1.Protein isolates were successfully extracted from catfish and tilapia muscle products. Extraction methods were optimized for each of the species under investigation. It was found that the alkaline-aided process gave the best isolate quality, while the acid-aided extraction process gave slightly higher protein recoveries for certain species. 2.Protein isolates were investigated for their functional properties, including gelation performance and solubility. Alkali-aided isolates were found to have superior gel forming abilities and higher functionality and stability. Lipid oxidation was significantly higher for proteins extracted with the acid aided process. 3.Injection studies demonstrated that isolates from the acid-aided process had lower viscosities than those from the alkali-aided process, and also had higher levels of oxidation products (as assessed by measuring thiobarbituric reactive substances and lipid hydroperoxides). Isolates from the acid-aided process
were also found to have an off-grey color, while the alkali-aided isolates where significantly whiter. Upon injection, the acid-aided isolates left visible streaks and spots of different color. Due to the above, the alkali-aided extraction technique was selected as the extraction method of choice to make injectable protein isolate suspensions. 4.A variety of protein isolate suspensions were produced from the proteins isolated with the alkali-aided process and incorporated into various seafood products with injection, soaking and tumbling, and compared with other protein sources (e.g. soy proteins) and additives (e.g. salt and phosphates). Our results showed that protein isolate suspensions were found to significantly reduce product drip loss, thaw loss and cook loss, as well as increasing "juiciness" of finished cooked products, better than any other ingredient tested. An increased level of "juiciness" was found to be linked to a decrease in fish muscle hardness as measured by Instron
testing, and decreased storage modulus of minced fish muscle as measured by oscillatory rheology. Level of incorporation was found to have a significant impact on product quality, with higher levels of addition generally yielding better cook yields than lower additions, with an accompanying increase in "juiciness". Injection was the most effective means to incorporate the isolate suspensions of all techniques tested.
Impacts
This project is expected to not only lead to better utilization of seafood byproducts, but also lead to the development of fish proteins as commercial and competitive ingredients for water control in seafood products and quality improvement of seafood products. Improvements in water-holding capacity should lead to improvements of US seafood products since products will be more palatable as well as more nutritious since more nutrients are retained as less water is lost. Furthermore more retained water in seafood product is expected to significantly improve the bottom line of the seafood processors and make them more competitive on not only a local but global scale.
Publications
- Davenport, M. P. and Kristinsson H. G. 2006. Influence of different setting temperatures on the gel forming ability of catfish protein isolates. IFT Annual Meeting, July 24-28, Orlando, FL. Abstract 020A-21.
- Kristinsson, H. G. and Ingadottir, B. 2006. Recovery and properties of muscle proteins extracted from tilapia (Oreochromis niloticus) light muscle by pH shift processing. J. Food Sci. 71, E132-E141. (50
- Kristinsson, H.G., Theodore, A. E., Ingadottir. 2006. Chemical processing methods for protein recovery from marine by-products and underutilized fish species. In: Shahidi, F, editor. Maximising the value of marine by-products, Cambridge, UK: Woodhead Publishing. pp. 144-167. (50
- Crynen, S. and Kristinsson, H. G. 2006. Properties of trehalose as a cryoprotectant and stabilizer of tilapia protein isolate. IFT Annual Meeting, July 24-28, Orlando, FL. Abstract 020A-20.
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