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Published on: January 27, 2014
Impact of microbial transglutaminase on gelling properties of Indian mackerel fish protein isolates
Sochaya Chanarat1, Soottawat Benjakul
1Department of Food Technology, Faculty of Agro-Industry, Prince of Songkla University, Hat Yai, Songkhla 90112, Thailand.
Abstract:
Impacts of microbial transglutaminase (MTGase) (0-0.6 units/g sample) on gel properties of Indian mackerel unwashed mince, surimi and protein isolates with and without prewashing were studied. Generally, lower myoglobin and lipid contents were found in protein isolate with and without prewashing, compared to those of unwashed mince and surimi (P<0.05). Protein isolate had the decreased Ca(2+)-ATPase and protein solubility, indicating protein denaturation. When MTGase was incorporated, breaking force and deformation of all gels markedly increased, especially as MTGase levels increased (P<0.05). At the same MTGase level, gel from protein isolate with prewashing exhibited the highest breaking force and deformation (P<0.05). The addition of MTGase could lower the expressible moisture content of most gels. No change in whiteness of gel was observed with the addition of MTGase (P>0.05), but gel from protein isolate gels had decreased whiteness as MTGase at high level was added. The microstructure of protein isolate gels without prewashing showed a similar network to unwashed mince gels, whilst a similar network was observed between surimi gel and gel from protein isolate with prewashing. Nevertheless, a larger void was noticeable in gels from protein isolates. All gels incorporated with MTGase (0.6 units/g) showed a slightly denser network than those without MTGase. Thus, gel with improved properties could be obtained from protein isolate from Indian mackerel with added MTGase.
Insights
Microbial transglutaminase (MTGase) improves Indian mackerel gel properties. Protein isolates with prewashing, enhanced by MTGase, showed the strongest gel structure and texture.
Area of Science:
- Food Science
- Biochemistry
- Marine Biotechnology
Background:
- Indian mackerel (Rastrelliger kanagurta) is a valuable fish resource.
- Understanding protein functionality is key to developing value-added fish products.
- Microbial transglutaminase (MTGase) is an enzyme known to improve protein cross-linking.
Purpose of the Study:
- To investigate the impact of microbial transglutaminase (MTGase) on the gel properties of Indian mackerel protein isolates and mince.
- To compare the effects of MTGase on different forms of Indian mackerel protein: unwashed mince, surimi, and protein isolates (with and without prewashing).
- To determine the optimal conditions for enhancing gel properties using MTGase.
Main Methods:
- Preparation of Indian mackerel mince, surimi, and protein isolates (prewashed and unwashed).
- Incorporation of varying concentrations of microbial transglutaminase (MTGase) into the samples.
- Analysis of gel properties including breaking force, deformation, expressible moisture, whiteness, and Ca(2+)-ATPase activity.
- Microstructural analysis using scanning electron microscopy.
Main Results:
- Protein isolates exhibited lower lipid and myoglobin content but decreased Ca(2+)-ATPase activity and solubility compared to mince and surimi.
- MTGase significantly increased the breaking force and deformation of all gels, with effects escalating with higher MTGase concentrations.
- Gels derived from prewashed protein isolates showed the highest breaking force and deformation at equivalent MTGase levels.
- MTGase reduced expressible moisture in most gels and resulted in a denser protein network, particularly at 0.6 units/g.
Conclusions:
- Microbial transglutaminase (MTGase) effectively enhances the gel-forming properties of Indian mackerel protein.
- Prewashed protein isolates are a promising substrate for producing high-quality gels when combined with MTGase.
- MTGase treatment leads to improved texture and reduced moisture loss in Indian mackerel-based gels.
