Optimizing the functional properties of the emulsion and foam kimia lentil protein isolate

Document Type : Original Article

Authors

• Mojgan Assadbeigi
• Nafiseh Zamindar
• Mohamad Goli

Department of Food Science and Industry, Islamic Azad University of Isfahan (Khorasgan), Isfahan, Iran

10.22067/ijpr.v14i1.2207-1041

Abstract

Introduction
In this study, the influence of three independent variables, namely temperature (ranging from 4 to 30 degrees Celsius), time (ranging from 20 to 60 minutes), and pH (ranging from 8.50 to 10), on the extraction of Kimia lentil protein, as well as the physical, chemical, and functional properties of the extracted protein, including emulsion capacity, emulsion stability, foam formation capacity, and foam stability, were evaluated. The response surface method, specifically the central composite design with 6 repetitions at the central point, was employed to conduct 20 standardized experiments. The maximum protein yield was achieved under the optimal conditions of a temperature of 30°C, a time of 20 minutes, and a pH value of 8.6. The highest foam stability was observed after 30 minutes of foam formation at a pH of 8.5, while the highest emulsifying capacity was observed at a pH of 10. The results of this research demonstrated that the lentil protein isolate from the Kimia variety can be effectively incorporated into food formulations, enhancing their nutritional value and functional characteristics. The lentil protein isolate is considered a high-quality natural protein and can serve as a valuable ingredient for improving the health benefits of food products or as a nutrient source on its own.
 
Materials and Methods
The raw material used in this research, including green lentil seeds of Kimia cultivar, was prepared from Kermanshah Agricultural Research Center. In order to model and optimize the conditions for protein extraction from green lentil seeds, the effect of independent variables including pH, centrifuge time and temperature, the response surface method (RSM) and Design Expert software were used. For this purpose, a central composite design with 5 levels and 6 replications at the central point during 20 performances was used to investigate the physicochemical and functional properties of green lentil protein isolate. The efficiency of lentil protein extraction was compared with the model predicted by t-student test at the probability level of 0.05.
 
Results and Discussion
The variables, temperature and time had no significant effect on the emulsifying capacity of lentil protein (p>0.05) and the variable pH has a significant effect (p<0.05). At a constant temperature of 4 degrees, the emulsifying capacity of lentil protein increases with increasing pH found. In addition, with the increase in time, the emulsifying capacity of lentil protein increased slightly, so that at pH 9.7 to 10, and the time from 52 to 60 minutes, lentil protein had the highest emulsifying capacity. The results of the study revealed that temperature, time, and pH exerted a significant effect on the stability of lentil protein emulsion (p<0.05). Specifically, the stability of the emulsion decreased as the pH and alkalinity of the environment increased, and as the time extended from 20 to 60 minutes. At a constant time of 40 minutes, increasing the temperature from 4 to 30 °C and raising the pH from 8.5 to 10 led to an increase in emulsion stability. While the stability of the emulsion showed slight improvement over time, temperature variations had minimal impact on its stability. The analysis of variance demonstrated that both pH and temperature had a significant effect on the foaming capacity of lentil protein (p<0.05), while time did not exhibit significant influence (p>0.05). Increasing the pH resulted in a decrease in the foaming capacity of lentil protein. Additionally, there was a slight decline in foaming capacity as the time increased from 20 to 60 minutes. Interestingly, the foaming capacity did not show any notable changes with variations in temperature. Regarding the stability of lentil protein foam after 30 minutes, the analysis of variance indicated significant effects of pH and temperature (p<0.05). As the pH increased, the volume and stability of the foam decreased. The maximum stability of the foam after 30 minutes of foam formation was observed at a pH of 8.5. The stability of the foam was not affected by changes in time, but a slight increase in foam stability was observed with higher temperatures.
 
Conclusion
In this study, optimization of extraction process conditions and evaluation of functional properties of lentil protein of Kimia variety was done using RSM method. The parameters of pH, time and temperature of extraction were selected as independent variables. The results showed that the quadratic statistical model can be used with high accuracy to predict the response parameters, and the optimization and prediction results of the model are in good agreement with the experimental results. The pH had a significant effect on the capacity and stability of the lentil protein emulsion, while the increase in pH led to a decrease in the foaming capacity and foam stability. With increasing temperature, foaming capacity, foam stability and emulsion stability increased. Also, increasing the temperature had no significant effect on the emulsifying capacity of lentil protein. The evaluation of the independent variable effect of time on the characteristics of lentil protein also showed that with the increase of time, the amount of foaming capacity, foam stability and emulsion stability of lentil protein decreased. Also, increasing the time did not have a significant effect on the emulsifying capacity of lentil protein. The presence of high protein content alone does not solely account for the improved functional characteristics observed. It is important to consider other compounds present in the sample, such as carbohydrates and fats, as they also influence the quality and functional properties of the protein. These factors collectively contribute to determining the overall functional characteristics of the lentil protein. The findings of this study highlight the potential of lentil protein as a readily available and abundant source of protein, along with other beneficial nutritional compounds, for use in the food industry. The results offer valuable insights into utilizing lentil protein to enhance the properties of food products and indicate its promising potential for formulating innovative food compositions. In summary, the research outcomes emphasize the favorable and appropriate functional characteristics of lentil protein, making it a valuable ingredient for improving food properties. This underscores the feasibility of incorporating lentil protein into food formulations to enhance their overall quality and nutritional profile.

Keywords

• Emulsion stability
• Foam capacity
• Lentil protein
• Optimization

Main Subjects

• Agronomy
• Food industry

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