Many commercially available beverages contain a wide selection of nutrients related to various health advantages. Furthermore, these beverages contain a mix of functional components that may be naturally present or formulated to enhance the health advantages of those products.

Recent strategies are sometimes developed to boost the functional properties of beverages. These can include, as an example, the incorporation of helpful ingredients equivalent to herbal extracts, minerals, and vitamins or, conversely, the removal of harmful components like fat and sugar.

Study: Demonstration of anti-oxidant properties of mustard seed (Brassica juncea) protein isolate in orange juice. Image Credit: Irina Ruchushkina / Shutterstock.com

Background

There are three varieties of functional beverages, of which include dairy-based beverages like probiotics, vegetable and fruit juices, in addition to sports and energy drinks. These beverages primarily contain chemical components with antioxidant (AOXs) activity.

A few of the common antioxidants present in these products are polyphenolics, carotenoids, and ascorbic acid (AA). Despite the helpful effect of those functional components, the presence of pro-oxidants (POXs) could cause opposed effects, as POXs are involved within the generation of hydrogen peroxide (H2O2) from mixtures of redox-active constituents like AA and polyphenols.

Many studies have reported the synthesis of H2O2 polyphenolic-rich beverages including coffee, green tea, and cocoa. Moreover, a high level of H2O2 has been reported in some sports and energy drinks whose predominant component is AA.

Recently, researchers have reported that an aqueous extract of citrus peel could effectively reduce the degrees of H2O2 in catechin-enriched green tea. Interestingly, additionally they found that the degrees of H2O2 in orange juice (OJ) are inversely related to the variety of proteins, dietary fiber, and unsaturated fat.

Proteins have unique potential as AOX additives in foods, as they’ll scavenge reactive oxygen species (ROS) through several mechanisms including reduction of hydroperoxides, interactions with free radicals, and chelation of pro-oxidative metals.

Diluted H2O2 adversely affects cells in vitro. Moreover, within the presence of transition metals and lightweight, H2O2 is converted to hydroxyl radicals that may propagate free radical chain reactions. This response can irreversibly alter cellular DNA, lipids, and cell membranes.

Typically, the H2O2 levels in AOX-rich functional beverages, equivalent to fruit juices, usually are not monitored.

In regards to the study

In a recent Food Chemistry study, researchers hypothesize that proteins with low dietary value could possibly be effectively used for AOX stabilization in OJ. On this study, scientists prepared a protein-enriched extract of mustard seed (Brassica juncea) and evaluated its efficacy against the production of H2O2 in fresh and thermally processed juice products.

The proteins extracted from mustard seeds are often known as mustard protein isolate (MPI). Thaumatin protein, which is present in lots of fruit juices, was used as a reference for comparative study.

Study findings

The degrees of H2O2 in 16 commercially available fruit and vegetable juices that were labeled as “fresh-like” and “thermally processed” were analyzed. The researchers estimated the degrees of H2O2 to be between zero to 7.3 µM within the ‘fresh’ juices and between zero and 15.0 µM within the processed juices. The very best level of H2O2 was observed in processed mango and pineapple juices, whereas no H2O2 was identified in fresh pineapple juices.

MPI contained about 51% protein and 6.4 mg GAe/g Total Solid (TS) total reducible substances, which were assumed to be secondary metabolites like polyphenolics. The dose-dependent suppression of H2O2 was observed in each fresh and thermally processed OJ within the presence of 0.1 mg/mL MPI after 24 hours. Nevertheless, such a discount process didn’t occur in fruit juices containing the reference protein.

The mix of proteins wealthy in thiol-containing amino acids, equivalent to methionine and cysteine, in addition to other antioxidant species in MPI, was found to effectively inhibit the autoxidation-mediated generation of H2O2 in OJ. This strategy is also applied to other commercially manufactured juices. 

Mustard seeds. Image Credit: Sunvic / Shutterstock

Conclusions

Low levels of H2O2 were observed in fresh juice, while an elevated level was present in processed juices. Furthermore, an inverse relationship between the protein content in OJ and the degrees of H2O2 was observed.

The present study reported that MPI can effectively suppress H2O2 properties with the reference protein present in the identical juice. Moreover, the MPI preparation utilized in this study contained additional compounds equivalent to polyphenolics and other extracted secondary metabolites that exhibited reducing properties.

The autoxidation response of functional beverages resulting in the production of H2O2 requires immediate attention. The removal or reduction of H2O2 in beverages through using MPI with AOX properties presents a promising strategy for industrial purposes. 

Journal reference:

• Bopitiya, D., Hearn, M. T. W., Zhang, J., & Bennett, L. E. (2022) Demonstration of anti-oxidant properties of mustard seed (Brassica juncea) protein isolate in orange juice. Food Chemistry. doi:10.1016/j.foodchem.2022.133648.