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Evaluation the Interaction between Anthocyanin and Whey Protein and Their Impact on Anthocyanin Color and Stability

Ren, Shuai, Ren
http://orcid.org/0000-0003-4219-1469
http://rave.ohiolink.edu/etdc/view?acc_num=osu1619007825035494

Abstract Details

2021, Doctor of Philosophy, Ohio State University, Food Science and Technology.
Anthocyanin (ACN) are naturally water-soluble flavonoids and used as food colorants to provide bright colors from blue to purple in food products. However, their sensitivity to degradation limits their application in food industry. Whey protein (WP), a functional and nutritional additive, has been shown to interact with ACN and enhance their color stability. Their interaction is affected by the WP structure, which may be affected by heat. The overall objective of this study was to explore the interaction mechanism between ACN and WP and learn the effect of their interaction on ACN color and stability. We chose three ACN sources (purple corn, grape and black carrot ACN) for this work based on their chemical structures and commercial values. The effects of thermally induced WP on color, stability (heat, UV light and storage) and antioxidant capacity of three ACN extracts was studied. WP (1mg/mL) was preheated at either 40, 50, 60, 70, or 80°C for 30 min to induce WP structure change. ACN were added to the preheated or native WP solutions and the mixtures were kept in the dark at 4°C for 4 weeks for storage stability study. DPPH method was used to measure antioxidant capacity. The protective effects of WP on ACN heat stability was tested by heating WP-ACN at 90°C for 2h. UV light stability was measured by exposing the samples to 254nm UV light at different times. Addition of WP improved ACN color stability during storage, with the smallest color change occurring when WP was preheated to 50°C. Color change (ΔE) for grape, purple corn, and black carrot ACN-WP (50°C) samples was about 40%, 23%, and 80% lower than their corresponding ACN control after storage for 4 weeks at 4°C. UV light-induced ACN color degradation decreased significantly (p<0.05) by 10–20% with addition of WP. Increasing preheating temperature (up to 80°C) increased ACN heat stability and antioxidant capacity while decreased UV-light stability. Antioxidant capacity decreased significantly (p<0.05) after addition of WP, while increased ACN survival. Thus, we conclude that thermally induced WP offers better protection to ACN from degradation during food processing and storage than native WP. The effect of WP-ACN interaction on ACN color and stability was further studied in the system containing ascorbic acid. ACN from purple corn, grape or black carrot were mixed with native WP or preheated WP (40–80°C) in various concentrations (0-10 mg/mL) in pH 3 buffer containing 0.05% AA and stored in the dark at 25°C for 5 days. WP addition increased ACN absorbance and protected ACN from AA-mediated degradation. Increasing WP concentration resulted in lower lightness and higher chroma, hue angle and color stability. The color loss of ACN solutions decreased 40%-50% when 10 mg/mL WP was added. Native WP showed more color enhancement and protection than thermally-induced WP. Increasing preheating temperature resulted in less absorbance increase and more absorbance loss. ACN half-life was improved by addition of WP and increased with increasing WP concentration. Native WP addition extended ACN half-life by about 2 times for purple corn and grape, and 1.31 times for black carrot ACN solutions. Preheating temperature did not significantly affect ACN protection by WP. WP addition might enhance ACN stability in beverages containing AA, expanding ACN application in foods. The binding mechanisms of ACN extracts to native and preheated WP (40–80°C, 3.6 μM) at pH 3 was studied by using fluorescence quenching spectroscopy. The fluorescence spectra were collected with an excitation wavelength of 280 nm at 25°C, 35°C and 45°C. The quenching data were analyzed by using the Stern–Volmer equation. The fluorescence of WP was quenched effectively by ACN. The fluorescence intensity of WP decreased (up to 73%) and its λmax increased (by ~5 nm) with increasing ACN concentration (0-100 μM). The quenching data showed that the interaction between ACN and WP was a static quenching process. Thermodynamic analysis showed their binding was mainly through hydrophobic interactions. Their binding affinity was higher for preheated WP than native WP and decreased gradually with increasing preheating temperature. Black carrot ACN extract had the lowest binding affinity with WP likely due to their larger molecular structure. The reaction mechanism of ACN-WP interaction was explored by using Fourier transform infrared spectra (IR). The IR were collected for native and preheated WP samples (40ºC-80ºC), as well as ACN-WP mixtures (pH 7.4, ACN 50 𝜇M, WP 5mg/ml) in the spectral range of 4000–700 cm−1. Soft independent modeling of class analogy (SIMCA) was used to analyze the IR data. WP secondary structure changed due to different heat treatment. The discrimination among different WP samples was mainly based on the amide I and amide II bands. WP heated at higher temperature had better separation and larger interclass distances to native WP, which indicated WP structure became more disordered at higher temperatures. The secondary structure of WP changed after interacted with ACN, which also affected by different ACN sources. The intensities of the amide I and II bands of WP decreased after binding with ACN, revealing that its α-helix content in the protein structure was decreased. All these results increase our understanding of the WP protection of ACN from degradation during food processing and storage and optimize the WP-ACN binding conditions, thus expanding ACN and WP applications in the food industry and facilitating the transition from synthetic dyes as food colorants to natural sources.
Monica Giusti (Advisor)
Christopher Simons (Committee Member)
Rafael Jimenez-Flores (Committee Member)
Lynn Knipe (Committee Member)
200 p.
Food Science

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Citations

  • Ren, Ren, S. (2021). Evaluation the Interaction between Anthocyanin and Whey Protein and Their Impact on Anthocyanin Color and Stability [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1619007825035494

    APA Style (7th edition)

  • Ren, Ren, Shuai. Evaluation the Interaction between Anthocyanin and Whey Protein and Their Impact on Anthocyanin Color and Stability. 2021. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1619007825035494.

    MLA Style (8th edition)

  • Ren, Ren, Shuai. "Evaluation the Interaction between Anthocyanin and Whey Protein and Their Impact on Anthocyanin Color and Stability." Doctoral dissertation, Ohio State University, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=osu1619007825035494

    Chicago Manual of Style (17th edition)

osu1619007825035494
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