Abstract
Currently, there is increased interest in finding appropriate food-grade green extraction systems capable of extracting these bioactive compounds from dietary mushrooms for applications in various food, pharmacological, or nutraceutical formulations. Herein, we evaluated a modified Swiss water process (SWP) method using alkaline and acidic pH at low and high temperature under pressurized conditions as a suitable green food grade solvent to obtained extracts enriched with myco-nutrients (dietary phenolics, total antioxidants (TAA), vitamins, and minerals) from Chaga. Ultra-high performance liquid chromatography coupled to high resolution accurate mass tandem mass spectrometry (UHPLC-HRAMS-MS/MS) was used to assess the phenolic compounds and vitamin levels in the extracts, while inductively coupled plasma mass spectrometry (ICP-MS) was used to determine the mineral contents. Over 20 phenolic compounds were quantitatively evaluated in the extracts and the highest total phenolic content (TPC) and total antioxidant activity (TAA) was observed at pH 11.5 at 100 °C. The most abundant phenolic compounds present in Chaga extracts included phenolic acids such as protocatechuic acid 4-glucoside (0.7–1.08 µg/mL), syringic acid (0.62–1.18 µg/mL), and myricetin (0.68–1.3 µg/mL). Vitamins are being reported for the first time in Chaga. Not only, a strong correlation was found for TPC with TAA (r-0.8, <0.0001), but also, with individual phenolics (i.e., Salicylic acid), lipophilic antioxidant activity (LAA), and total antioxidant minerals (TAM). pH 2.5 at 100 °C treatment shows superior effects in extracting the B vitamins whereas pH 2.5 at 60 and 100 °C treatments were outstanding for extraction of total fat-soluble vitamins. Vitamin E content was the highest for the fat-soluble vitamins in the Chaga extract under acidic pH (2.5) and high temp. (100 °C) and ranges between 50 to 175 µg/100 g Chaga. Antioxidant minerals ranged from 85.94 µg/g (pH7 at 100 °C) to 113.86 µg/g DW (pH2.5 at 100 °C). High temperature 100 °C and a pH of 2.5 or 9.5. The treatment of pH 11.5 at 100 °C was the most useful for recovering phenolics and antioxidants from Chaga including several phenolic compounds reported for the first time in Chaga. SWP is being proposed herein for the first time as a novel, green food-grade solvent system for the extraction of myco-nutrients from Chaga and have potential applications as a suitable approach to extract nutrients from other matrices. Chaga extracts enriched with bioactive myconutrients and antioxidants may be suitable for further use or applications in the food and nutraceutical industries.
Highlights
Functional foods refer to food products or ingredients that are useful in providing known health benefits beyond basic nutritional requirements [1]
The total phenolic content (TPC) and Total Antioxidant Activity (TAA) were grouped with the hydrophilic phenolic content (HPC), and Hydrophilic antioxidant activity (HAA) under these extraction conditions, while the lipophilic phenolic content (LPC) clustered with extracts obtained at pH 2.5/60 ◦ C, pH 2.5/100 ◦ C, and pH 7/100 ◦ C
The correlation coefficient (r = 0.78) between TAA and TPC, suggested that approximately 78% of the extracts’ total antioxidants may be attributed to the TPC present in the extract, which was driven by the high association of the HPC with the TAA (r = 0.81). These findings suggest that the hydrophilic phenolics are a major contributor to the TAA of the extracts obtained in this extraction system
Summary
Functional foods refer to food products or ingredients that are useful in providing known health benefits beyond basic nutritional requirements [1]. One of the most common dietary mushrooms used as a functional food ingredient and having several health benefits in traditional and folk medicine is Chaga (Inonotus obliquus) [5]. In the Holarctic regions of Canada, the USA, Asia, and Europe (mainly Russia, Japan, Siberia, and Korea) In these regions, Chaga is highly valued for its use as a therapeutic drink and in enhancing the immune system in traditional or folk medicine [8]. Previous studies have reported that Chaga polyphenols and superoxide dismutase enzyme form a potent antioxidant system associated with reduced oxidative stress, diabetes, cancer, and cardiovascular disease risks [11,12] These health benefits of Chaga are due to its high myco-nutrient content [13]. 3 ofbioactive with some of the organic solvents typically employed for extracting compounds from Chaga [19]
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