Quantification of Protein Content in Protein Powder Supplement by Using Modified Lowry Method.

Chia, Chang Lin (2019) Quantification of Protein Content in Protein Powder Supplement by Using Modified Lowry Method. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

The objective of this study is to study the effectiveness of modified Lowry method by comparing the protein content determined by modified Lowry with original Lowry. Reasons that chooses Lowry for modification despite there are already Kjeldahl method as Association of Official Analytical Chemists (AOAC) standard is that Lowry is safer in term of reagents, less time consuming and lower cost. Five modifications have been done to original Lowry and tested on protein powder supplement used by gym athletes. Modifications including protein precipitation by using trichloroacetic acid (TCA), removing reducing agent by using hydrogen peroxide, removing lipid interference by using sodium dodecyl sulfate (SDS), accelerate colour development and improving stability of alkaline copper reagent. Generally all modification shown an improvement when compared to original Lowry. TCA helps to improve protein recovery by precipitating it. Hydrogen peroxide and SDS helps to remove interference substance such as lipid and reducing agent. Modified of alkaline copper reagent helps to shorten the reaction time of Folin-Ciocalteau Phenol reagent with protein sample for colour development. Addition of NaOH help to stabilize the alkaline copper solution and preventing it from crystallization. Findings of the research shows that all modification can be used as an alternative improvement for the original Lowry method. Keywords: Protein Powder Supplement, original Lowry method, modified Lowry method.