Comparison of antioxidant activities of bovine whey proteins before and after simulated gastrointestinal digestion

Abstract

Oxidative stress caused by free radicals has been implicated in several human disorders. Dietary antioxidants can help the body to counteract those reactive species and reduce oxidative stress. Antioxidant activity is one of the multiple health-promoting attributes assigned to bovine whey products. The present study investigated whether this activity was retained during upper gut transit using a static simulated in vitro gastrointestinal digestion (SGID) model. The capacity to scavenge free radicals and reduce ferric ion of whey protein isolate (WPI), individual whey proteins, and hydrolysates pre-and post-SGID were measured and compared using various antioxidant assays. In addition, the free AA released from individual protein fractions in physiological gut conditions were characterized. Our results indicated that the antioxidant activity of WPI after exposure to the harsh conditions of the upper gut significantly increased compared with intact WPI. From an antioxidant bioactivity viewpoint, this exposure negates the need for prior hydrolysis of WPI. The whey protein α-lactalbumin showed the highest antioxidant properties post-SGID (oxygen radical absorbance capacity = 1,825.94 ± 50.21 μmol of Trolox equivalents/g of powder) of the 4 major whey proteins tested with the release of the highest amount of the antioxidant AA tryptophan, 6.955 μmol of tryptophan/g of protein. Therefore, α-lactalbumin should be the preferred whey protein in food formulations to boost antioxidant defenses.

Effects of Storage Time and Temperature on Antioxidants in Juice from Momordica charantia L. and Momordica charantia L. var. abbreviata Ser.

“…For example, tryptophan is a well-known antioxidant against peroxyl radicals and can exert its antioxidant ability by electron transfer mechanism or hydrogen atom transfer [39]. Phenylalanine with phenolic hydroxyl group has DPPH scavenging activity and ferric ion reducing power [40]. Balsaminoside C is a cucurbitane-type triterpenoid and can serve as an antioxidant agent for the treatment of reactive oxygen species-induced diseases [41].…”

Physicochemical and Antioxidative Characteristics of Potato Protein Isolate Hydrolysate

“…Endoproteases and exoproteases including bromelain, Neutrase, and Flavourzyme have been used to hydrolyze proteins to produce protein isolate hydrolysates showing antioxidant activities [ 16 ]. Among these proteases, bromelain (EC 3.4.22.32) is a cysteine endoprotease derived from pineapple stems, and it has also been demonstrated to be a safe and effective food supplement [ 17 ].…”

Optimization and Identification of Antioxidant Peptide from Underutilized Dunaliella salina Protein: Extraction, In Vitro Gastrointestinal Digestion, and Fractionation

“…Ultrasound assisted extraction has been considered as an efficient and green/ecofriendly technology to disrupt the matrices and subsequently release the target component by bubble cavitation at mild condition in short time [27, 28]. Meanwhile, it has been reported that the technique of enzymolysis could be employed to search the new and small molecular peptide with stronger DPPH• scavenging ability and other bioactivities [29, 30]. In addition, whether the stability of bioactivity was retained during the gastrointestinal digestive juice might be a large block for preparation of peptide with marked bioactivities practical application in human.…”