Elsevier

Food Chemistry

Volume 149, 15 April 2014, Pages 54-61
Food Chemistry

Comparison of four kinds of extraction techniques and kinetics of microwave-assisted extraction of vanillin from Vanilla planifolia Andrews

https://doi.org/10.1016/j.foodchem.2013.10.052Get rights and content

Highlights

  • MAE showed the stronger extraction efficiency than maceration, UAE and PAE.

  • MAE extracts gave high antioxidant activity and great odours intensity.

  • Powdered vanilla with a sample/solvent of 4 g/100 ml is effective to extract vanillin.

  • Two side kinetic equation is qualified for the description of vanillin extraction.

  • The developed model can be used to predict vanillin yield extracted from vanilla.

Abstract

Vanillin yield, microscopic structure, antioxidant activity and overall odour of vanilla extracts obtained by different treatments were investigated. MAE showed the strongest extraction power, shortest time and highest antioxidant activity. Maceration gave higher vanillin yields than UAE and PAE, similar antioxidant activity with UAE, but longer times than UAE and PAE. Overall odour intensity of different vanilla extracts obtained by UAE, PAE and MAE were similar, while higher than maceration extracts. Then, powered vanilla bean with a sample/solvent ratio of 4 g/100 mL was selected as the optimum condition for MAE. Next, compared with other three equations, two-site kinetic equation with lowest RMSD and highest Radj2 was shown to be more suitable in describing the kinetics of vanillin extraction. By fitting the parameters Ceq, k1, k2, and f, a kinetics model was constructed to describe vanillin extraction in terms of irradiation power, ethanol concentration, and extraction time.

Introduction

Vanilla (Vanilla planifolia Andrews), a crop grown in tropical and subtropical areas, is one of the most widely used flavoring in confectionery, food products, beverages, ice cream, perfume, and pharmaceutical preparations in the world (Gu et al., 2012, Zidi et al., 2011). Vanillin (4-hydroxy-3-methoxybenzaldehyde), which was first isolated from vanilla in 1816, is the major flavor constituent of vanilla (Al-Naqeb et al., 2010, Perez-Silva et al., 2011). Currently, cured vanilla pods are the main source of natural vanillin. Aside from its appealing aroma, vanillin and vanilla extracts have also been reported to possess various health benefits, such as antioxidant, anti-mutagenic, hypolipidemic activity, and have considerable potential as food preservative and anticarcinogen (Al-Naqeb et al., 2010, Andrade et al., 1992, Jadhav et al., 2009, Sharma et al., 2006).

An increasing number of consumers prefer food from natural sources because of food safety concerns. However, natural vanillin, which has price varying from 1200 USD/kg to 4000 USD/kg, can only supply less than 1% of the total market demand (Kumar et al., 2010, Zidi et al., 2011).

Conventional methods for extracting bioactive compounds from foods and natural products, such as Soxhlet and maceration, usually require prolonged extraction time, large quantity of solvents, and heavy capital investment (Valdez-Flores and Canizares-Macias, 2007, Jadhav et al., 2009, Longare-Patron and Canizares-Macias, 2006). In recent years, some novel extraction techniques such as ultrasound-assisted extraction (UAE), pressure-assisted extraction (PAE) and microwave-assisted extraction (MAE) have been developed, as a result of their inherent advantages over conventional extraction methods, such as high extractive power, shorter time, less solvent, and lower cost.

Among these extraction methods, microwave-assisted extraction (MAE), an environmentally friendly process with economic advantages, is part of the Microwave Assisted Process (MAP) developed and patented by the Federal Department of the Environment in Canada (Alfaro, Belanger, Padilla, & Pare, 2003). MAE is based on the direct application of electromagnetic radiation on a material that has the ability to absorb electromagnetic energy and transform the energy into heat (Xie et al., 2010). Auxiliary energy enables extraction processes to shorten their analysis time, lower their energy consumption, require less amount of solvent, and produce higher yields compared with conventional extraction methods (Longare-Patron and Canizares-Macias, 2006, Xie et al., 2010). In recent years, MAE has been widely used to extract various biologically active compounds from different plant materials, such as the extraction of aloe-emodin from aloe and extraction of phenolics from beans (Beejmohun et al., 2007, Sturzoiu et al., 2011).

Several papers have compared two or three extraction methods on the yield of vanillin extracted from vanilla beans. According to their results, new methods always gave higher vanillin yield or were less time-consuming than conventional methods (Jadhav et al., 2009, Longare-Patron and Canizares-Macias, 2006, Sharma et al., 2006). However, to the best of our knowledge, so far there is no report about the comparison of antioxidant activity and odour of vanilla extracts, and also little report about the extraction kinetics for vanillin.

In the first part of this research, the extracting efficiency of vanillin, antioxidant activity and odour of different vanilla extracts processed by maceration, UAE, PAE and MAE were systematically compared. In the second part, the effects of particle sizes and sample/solvent ratios for MAE on vanillin yield were investigated and the extraction conditions were optimised. Lastly, an extraction kinetic model describing the extraction process was successfully constructed.

Section snippets

Materials and chemicals

Cured vanilla beans were obtained from the Spice and Beverage Research Institute (Hainan, China). The vanilla beans were chopped by hand or grounded to powder in an electric grinder (Yili, Zhejiang, China). The average particle size 0.630 mm was determined using a sieve analysis. Vanillin, 2, 2-Diphenyl-1-picrylhydrazyl (DPPH) and ascorbic acid were sourced from Sigma Chemical Company (St. Louis, MO, USA). Methanol (high performance liquid chromatography (HPLC) grade) for HPLC analysis and

Vanillin yield

In the extraction process of plant material, besides free diffusion, exterior function such as microwave radiation, ultrasound radiation, and pressure which contribute to the reduction of mass transfer resistances could produce an enormous impact on the extraction process. In the views of Martins, Aguilar, Garza-Rodriguez, Mussattoa, and Teixeira (2010), the rapid temperature rise and the internal pressure increase generated by the microwave radiation resulted in the release of target

Conclusions

Maceration, UAE, PAE and MAE were systematically compared in the vanilla extraction process. By the investigation of microscopic structures, significant differences such as cell integrity and colour changing were observed between blank and treated samples. By the comparison of vanillin yields and extraction rates, MAE showed the highest extraction power whereas shortest extraction time in the four methods. Although yields of UAE and PAE were lower than maceration, the extraction processes of

Acknowledgements

The authors would like to thank Spice and Beverage Research Institute, Chinese academy of tropical agricultural for their valuable support in this work. This study was funded by the National Science and technology support program (2012BAD36B03) and Chinese Central Public-interest Scientific Institution Basal Research Fund (1630052012017).

References (30)

  • C. Zidi et al.

    A supported liquid membrane system for efficient extraction of vanillin from aqueous solutions

    Separation and Purification Technology

    (2011)
  • H.H.R. Andrade et al.

    Suppressing effect of vanillin on chromosome aberrations that occur spontaneously or are induced by mitomycin C in the germ cell line of Drosophila melanogaster

    Mutation Research

    (1992)
  • V. Beejmohun et al.

    Microwave-assisted extraction of the main phenolic compounds in flaxseed

    Phytochemical Analysis

    (2007)
  • F. Gu et al.

    Optimization of enzymatic process for vanillin extraction using response surface methodology

    Molecules

    (2012)
  • S. Jokic et al.

    Modelling of the process of solid–liquid extraction of total polyphenols from soybeans

    Czech Journal of Food Sciences

    (2010)
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