Elsevier

Food Chemistry

Volume 217, 15 February 2017, Pages 91-97
Food Chemistry

Salting-out extraction of allicin from garlic (Allium sativum L.) based on ethanol/ammonium sulfate in laboratory and pilot scale

https://doi.org/10.1016/j.foodchem.2016.08.092Get rights and content

Highlights

  • Salting-out extraction of allicin using ethanol/salt aqueous two-phase system.

  • Response surface methodology was developed to optimize the extraction conditions.

  • The bioactive actions were tested using allicin obtained by salting-out extraction.

  • The extraction was amplified in pilot scale under the optimized conditions.

Abstract

Salting-out extraction (SOE) based on lower molecular organic solvent and inorganic salt was considered as a good substitute for conventional polymers aqueous two-phase extraction (ATPE) used for the extraction of some bioactive compounds from natural plants resources. In this study, the ethanol/ammonium sulfate was screened as the optimal SOE system for the extraction and preliminary purification of allicin from garlic. Response surface methodology (RSM) was developed to optimize the major conditions. The maximum extraction efficiency of 94.17% was obtained at the optimized conditions for routine use: 23% (w/w) ethanol concentration and 24% (w/w) salt concentration, 31 g/L loaded sample at 25 °C with pH being not adjusted. The extraction efficiency had no obvious decrease after amplification of the extraction. This ethanol/ammonium sulfate SOE is much simpler, cheaper, and effective, which has the potentiality of scale-up production for the extraction and purification of other compounds from plant resources.

Introduction

Garlic (Allium sativum L.) is a well-known edible and medicinal plant since ancient China. Allicin (diallylthiosulfinate) is an organosulfur compound, and it is one major biological active substance in garlic (Tyagi, Pradhan, Srivastava, & Mehrotra, 2014). Actually, allicin is converted from alliin after crushing of the garlic clove under the action of alliinase (Amagase et al., 2001, Ankri and Mirelman, 1999). Allicin was first studied for its antibacterial properties in the middle of 20th century (Cavallito & Bailey, 1944), then its other pharmacological actions of anti-oxidant, antifungal, antihypertensive, anti-inflammatory, and inhibition of tumor were also found (El-Kashef et al., 2015, Hirsch et al., 2000, Liu et al., 2015). Up to now, the solvent extraction using water or ethanol aqueous solution (Arzanlou and Bohlooli, 2010, Bocchini et al., 2001, Wang et al., 2014) and supercritical fluid extraction (SFE) (del Valle et al., 2012, Liang et al., 2012, Rybak et al., 2004) are the most widely used methods for the extraction of allicin from garlic in laboratory, pilot or large scale. However, the solvent extraction can obtain the crude extract and the samples need further purification; SFE requires sophisticated instrument and high cost.

Aqueous two-phase extraction (ATPE) was first introduced by Albersson, and the most commonly used two aqueous two-phase systems (ATPSs) were PEG/salt and PEG/dextran (Albertsson, 1986). ATPS based on low molecular organic solvents (e.g. methanol, ethanol, acetone, and n-propanol) and inorganic salts had been developed in recent years, which can also be called salting-out extraction (SOE) system (Dong et al., 2016). Compared with polymer ATPS, SOE has the advantages of lower cost, lower viscosity, quicker phase separation time, relatively lower environmental toxicity and easier to scale up (Amid et al., 2012, Fu et al., 2015, Liu et al., 2014, Ooi et al., 2009, Wang et al., 2010). SOE systems had been used to extract various bioactive compounds from different plants resources, such as anthocyanins from grape juice (Wu et al., 2014), alkaloids from Sophora flavescens Ait. (Zhang et al., 2015), phenolic compounds from Ficus carica L. (Feng et al., 2015), rutin from acerola waste (Reis et al., 2014), lignans from Zanthoxylum armatum (Guo, Su, Huang, Wang, & Li, 2015), and polysaccharides from Semen Cassiae (Chen et al., 2016).

The objective of this study is to use SOE for the extraction and preliminary purification of allicin from garlic powder. The allicin is extracted into alcohol-rich phase, while partial impurities are extracted into the salt-rich phase. The extraction conditions were optimized at laboratory scale, SOE was scaled up to the pilot scale under the optimized conditions. The phase-forming components of ethanol and ammonium sulfate were recycled and reused.

Section snippets

Materials and reagents

The garlic samples were originated in Shandong province and bought from the Vanguard supermarket in Changsha City, Hunan Province. The allicin standard was purchased from National Institutes for Food and Drug Control (Beijing, China) with HPLC purity larger than 98%. HPLC grade acetonitrile was purchased from TEDIA Company, Inc. (Fairfield, OH, USA). The analytical reagents of different organic solvents (ethanol, n-proanol, isopropanol, acetone and acetonitrile) and salts (ammonium sulfate,

Selection of the optimum SOE system

To screen the optimal SOE system for the extraction and isolation of allicin, various organic solvents (ethanol, n-propanol, isopropanol, acetone and acetonitrile) and salts (ammonium sulfate, sodium dihydrogen phosphate, sodium sulfate, and potassium phosphate) were considered as the phase-forming components. The binodal curves were shown in Fig. 1, which imply that the closer the binodal curves to the coordinates, the less salt (organic solvent) required for forming two phases under the same

Conclusions

In this work, ethanol/ammonium sulfate ATPS was successfully applied for the SOE of allicin from garlic in laboratory and pilot scale. The factors influencing the SOE were investigated in detail. The obtained optimum results were as follows: 24% (w/w) ethanol concentration, 23% (w/w) ammonium sulfate concentration, 40 g/L loaded sample at room temperature with pH being not adjusted. The major three influencing factors were further optimized by RSM. The optimized conditions were 22.57% (w/w)

Acknowledgement

This work was financially supported by the National Natural Science Foundation of China (No. 21406262).

References (39)

Cited by (55)

  • Allicin: A review of its important pharmacological activities

    2023, Pharmacological Research - Modern Chinese Medicine
View all citing articles on Scopus
View full text