In vitro digestion and cellular antioxidant activity of beta-carotene-loaded emulsion stabilized by soy protein isolate-Pleurotus eryngii polysaccharide conjugates

Authors: HU, QIUHUI - Nanjing University; WU, YILIANG - Nanjing University; ZHONG, LEI - Nanjing Agricultural University; MA, NING - Nanjing University; ZHAO, LIYAN - Nanjing University; MA, GAOXING - Nanjing University; CHENG, NINGHUI - Children'S Nutrition Research Center (CNRC); Nakata, Paul; XU, JUAN - Nanjing University

Submitted to: Food Hydrocolloids
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/14/2020
Publication Date: 9/16/2020
Citation: Hu, Q., Wu, Y., Zhong, L., Ma, N., Zhao, L., Ma, G., Cheng, N., Nakata, P.A., Xu, J. 2020. In vitro digestion and cellular antioxidant activity of beta-carotene-loaded emulsion stabilized by soy protein isolate-Pleurotus eryngii polysaccharide conjugates. Food Hydrocolloids. 112:106340. https://doi.org/10.1016/j.foodhyd.2020.106340.
DOI: https://doi.org/10.1016/j.foodhyd.2020.106340

Interpretive Summary: Beta-carotene is the primary carotenoid in carrots. Beta-carotene not only gives the carrot its orange color but is also associated with a number of health benefits. Incorporation of Beta-carotene in various food stuffs has been limited by its poor solubility in water and susceptibility to heat, light, and oxygen. In this study, we show that these limitations can be overcome by encapsulating the Beta-carotene in an oil-water emulsion utilizing proteins derived from soybeans and polysaccharides derived from mushroom. Our study suggests that the increase in solubility and emulsification properties results from the links formed between the protein and polysaccharides which occur upon heating. In addition, we show that encapsulating the Beta-carotene enhances its absorption in a simulated digestion and absorption cell model that mimics this process in humans. Based on studies already published in the literature, the use of soybean protein isolates and mushroom polysaccharides will also provide added nutritional and health benefits.

Technical Abstract: Beta-Carotene is a natural fat-soluble antioxidant, while the poor oral bioavailability of beta-carotene restricts its application for functional foods. To overcome this barrier, a stable oil-in-water emulsion was structured to effectively deliver beta-carotene. In this study, soy protein isolate (SPI)-Pleurotus eryngii polysaccharide (PEP) conjugate was prepared by Maillard reaction under controlled wet-heating conditions. Beta-carotene was encap- sulated in SPI-PEP conjugate-stabilized emulsion and its gastrointestinal behavior and antioxidant activity were assessed in vitro. The results showed that such conjugate with high molecular weight was mainly formed through PEP covalently binding to lysine and cysteine of SPI via C–N. Changes in spatial structure of SPI-PEP conjugate resulted from its decreased tryptophan fluorescence intensity and unfolded protein secondary structure. A decreased surface hydrophobicity and flat surface morphology of SPI-PEP conjugate contributed to its increased water solubility and emulsibility. Additionally, lipid digestion and the formation of mixed micelles were promoted in SPI-PEP conjugate-stabilized emulsion due to its strong steric repulsion, resulting in an improved bioavailability of beta-carotene. Such improvement was favorable for beta-carotene to relieve tert-butyl hydroperoxide-induced oxidative stress by decreasing reactive oxygen species production and enhancing antioxidant enzyme activities in Caco-2 cells. Our study suggested that Maillard-type protein-polysaccharide conjugates stabilized emulsions had a potential industry application for the delivery of fat-soluble nutrients.