Optimization model for ultrasonic-assisted and scale-up extraction of anthocyanins from Pyrus communis ‘Starkrimson’ fruit peel
Introduction
The need and applications of plant-derived bioactive compounds and extracts are increasing over the past several years mainly as nutraceuticals for promoting human health. Among several plant-derived bioactive compounds, anthocyanins are one of the special classes of flavonoid compounds which has been recognized for its multi-functional and multi-industrial applications (Khoo, Azlan, Tang, & Lim, 2017). From transparency market research report (TMR, 2019), the anthocyanin market in the year 2018 was over US$ 500 million, which was expected to increase with a compound annual growth rate (CAGR) of 4.6% from 2019 to 2026. Among other anthocyanin compounds, cyanidin-3-O-galactoside (Cy3-gal) contain 3-O-beta-d-galactoside group esterified to the 3rd position of the C ring of cyanidin. The natural occurrence of Cy3-gal is limited to some fruit and berry species such as Aronia melanocarpa (Chocke berries), Vaccinium macrocarpon (Cranberries), Vaccinium vitis-idaea (Lingon berries), Amelan chieralnifolia (Saskatoon berries), Empetrum nigrum (Crow berries), Pyrus pyrifolia and Pyrus communis (Lin and Harnly, 2008, Zhang et al., 2012, Fang, 2015). Anthocyanins were well tested for their health effects and found effective against a variety of disease conditions (Li et al., 2017, Belwal et al., 2017). Specifically, Cy3-gal was found to improve spatial memory (Tan et al., 2014), and showed strong antioxidant and cytoprotective activity (Bellocco et al., 2016). Moreover, anthocyanins are also gaining pace as a natural colorant in food, bevrages, pharmaceutical and cosmetic products (Khoo et al., 2017). Also, it has been reported that among different anthocyanin compounds, cyanidin market share was found to be the highest (~30%) compared to other common anthocyanins (TMR, 2019).
Extraction is an important and crucial step in plant and food processing in terms of extracting desired bioactive compounds in their optimum yield without affecting their functional qualities (Chemat et al., 2017, Chemat et al., 2017, Belwal et al., 2018). Ultrasonic-assisted extraction (UAE) is one of the advanced forms of classical extraction techniques and uses ultrasonic waves to generate cavitation bubbles which on collision generate a hot spot/micro-jet with higher temperature and pressure, thus resulting in faster and efficient extraction of components from the plant matrix (Chemat, Rombaut, Sicaire et al., 2017). The extract quality and yield are significantly affected by various UAE factors, such as ultrasonic power/intensity, reaction vessel type, extraction temperature and time, solvent pH, concentration and volume (Pandey et al., 2018, Huang et al., 2019). More specifically, UAE has been widely used and optimized for the extraction of anthocyanins from plant samples (Zou et al., 2011, Celli et al., 2015) and also in our previous work (Huang et al., 2019). Thus, determination of significant process factors and optimization of their levels for getting superior quality of extract are prerequisite.
Pyrus communis fruits are cultivated and consumed in larger quantities especially in China (Silva, Souza, Barbieri, & De Oliveira, 2014). From the available report, in the year 2017–18 the global production of Pears is recorded as 24.17 million metric tons, led by China with approximately 80% of the total production (Report on ‘Major pear producing countries worldwide 2017/2018). The Starkrimson cultivar of Pyrus communis, also known as ‘Hongpi’ in Chinese, is known for its attractive crimson red color. Pyrus is consumed as raw fruit and also used in the preparation of various food products such as pies, cakes, cheese, carpaccio, risotto, jams, and ice creams, due to its pleasant taste and low calorie value (Silva et al., 2014). The food processing of Pyrus fruits mainly requires removal of its peel and core, which are considered as a waste (Featherstone, 2016). However, the peel contains valuable bioactive compounds and has studied for its chemical profiling and bioactivity. For instance, among ten different pear varieties, the peel contained a higher concentration of bioactive compounds especially polyphenols as compared to its flesh (Li et al., 2014). The peel of red cultivars of Pyrus fruit is also a rich source of anthocyanins, among which concentration of Cy3-gal was reported the highest (∼93%) (Huang, Zhang, Qin, Wenquan, & Wu, 2012). Moreover, studies (Wu et al., 2019) revealed that Starkrimson has highest anthocyanin content as compared to other red Asian and European pear cultivars (i.e., 5 Hao, Red Zaosu, Red Sichou, Palacer, and Red Bartlett).
A number of studies have been conducted on UAE optimization of anthocyanins from various plant sources. Nevertheless, very few studies were conducted on utilizing food waste for bioactive compound recovery under optimized advanced extraction conditions. No such studies have been proposed for UAE optimization of anthocyanins (especially Cy3-gal) from fruit peel waste and further tested for its higher volume extraction. Thus, keeping in mind the high anthocyanin contents in fruit peel of Pyrus communis ‘Starkrimson’, the present study was designed to test the ultrasonic effect on extraction of Cy3-gal and further testing for its batch and continuous scale-up extraction process. The UAE was also compared with the conventional extraction (CE) method.
Section snippets
Chemicals and reagents
Cyanidin-3-O-galactoside (Idaein chloride, ≥90%) and cyanidin-3-O-glucoside (Kuromanin chloride, ≥95%) standards were procured from Sigma Chemicals (Sigma-Aldrich, USA). 2,2-diphenyl-1-picrylhydrazyl (DPPH), 2,4,6-tri(2-pryridyl)1,3,5-triazine (TPTZ), ascorbic acid, analytical grade ethanol, methanol, acetone, trifluoroacetic acid, hydrochloric acid, formic acid and LC-MS grade acetonitrile were purchased from Aladdin Industrial Corporation (Shanghai, China). For solvent dilution and mobile
Selection of factors and their levels
With increasing ultrasonic power from 60 to 200 W, a significant higher extraction yield (0.29 mg/g) of Cy3-gal was recorded (Fig. 1A). However, it was interesting to note that a significant (p < 0.05) decreased in Cy3-gal extraction yield was recorded when applied lower (60 W) and higher (400 and 600 W) ultrasonic power (Fig. 1A). Ultrasonic power played an important role in the extraction of compounds due to cavitation effect. As seen from the single factor study, moderate ultrasonication
Conclusions
The present study is an attempt to determine the ultrasonication factors, mechanism and especially their relation with viscosity for optimizing cyanidin-3-O-galactoside extraction yield from Pyrus communis ‘Starkrimson’ fruit peel. And further project a scale-up model for higher volume extraction. The results revealed a significant role of ultrasonication during extraction of anthocyanins, which was justified by higher Cy3-gal extraction yield and deformations of the cell surface compared to
Declaration of Competing Interest
None.
Acknowledgments
The research was financially supported by the Key Research and Development Program of Zhejiang Province (2018C02049), China; Special Fund for Science and Technology Base and Talent of Guangxi (GKAD17195088), China; Technology Innovation Programme of Zhejiang Province (ZJWR0102001), China; Hangzhou Science and Technology Development Program (20180432B31), China and China Postdoctoral Science Foundation (2018M642443), China.
References (65)
- et al.
“Solvent-free” ultrasound-assisted extraction of lipids from fresh microalgae cells: A green, clean and scalable process
Bioresource Technology
(2012) - et al.
Effects of high-intensity ultrasound process parameters on the phenolic compounds recovery from araticum peel
Ultrasonics Sonochemistry
(2019) - et al.
Cyanidin-3-O-galactoside in ripe pistachio (Pistachia vera L. variety Bronte) hulls: Identification and evaluation of its antioxidant and cytoprotective activities
Journal of Functional Foods
(2016) - et al.
A critical analysis of extraction techniques used for botanicals: Trends, priorities, industrial uses and optimization strategies
TrAC Trends in Analytical Chemistry
(2018) - et al.
The ferric reducing ability of plasma (FRAP) as a measure of “antioxidant power”: The FRAP assay
Analytical Biochemistry
(1996) - et al.
Effect of solvents extraction on phenolic content and antioxidant activity of the byproduct of eggplant
Industrial Crops and Products
(2013) - et al.
Use of a free radical method to evaluate antioxidant activity
Lebensmittel-Wissenschaft and Technologie
(1995) - et al.
Conventional, ultrasound-assisted, and accelerated-solvent extractions of anthocyanins from purple sweet potatoes
Food Chemistry
(2016) - et al.
Optimization of ultrasound-assisted extraction of anthocyanins from haskap berries (Lonicera caerulea L.) using Response Surface Methodology
Ultrasonics Sonochemistry
(2015) - et al.
Review of Green Food Processing techniques. Preservation, transformation, and extraction
Innovative Food Science and Emerging Technologies
(2017)