Comparative analyses of aromas of fresh, naringinase-treated and resin-absorbed juices of pummelo by GC-MS and sensory evaluation

Comparative analyses of aromas of fresh,

naringinase-treated and resin-absorbed juices

of pummelo by GC-MS and sensory evaluation

Hui Ni,a,b Peng Hong,a Hai Feng Ji,a Hao Sun,a Yan Hong Chen,a,d

An Feng Xiaoa,c,d and Feng Chena,b*

ABSTRACT: Resin adsorption and naringinase treatment represent two major methods for debittering naringin in citrus juices,

but their effects on the aroma profiles of citrus juices have not been intensively investigated yet. In this study, the volatiles of

the fresh, naringinase-treated and resin-absorbed juices of pummelo were investigated by gas chromatography coupled with

a mass spectrometer (GC-MS) and sensory evaluation. The fresh juice was analyzed to have 24 volatiles, among which (E)-3-

hexen-1-ol and 1-hexanol had the highest concentrations. After the naringinase treatment, the juice showed 32 volatiles, among

which (Z)- and (E)-linalool oxides were the most dominant in concentration; while the resin adsorption captured most of the vol￾atiles. Principal component analysis (PCA) showed that naringinase treatment led to an increase in some compounds, particularly

aldehydes, whereas resin adsorption decreased the amounts of a lot of volatile compounds. The sensory evaluation demon￾strated the fresh and naringinase-treated juices had similar aroma profiles, whereas the resin-adsorbed juice had a much weaker

aroma intensity than its counterparts. These results indicated that the naringinase treatment is more desirable than the resin

adsorption for debittering citrus juice because the naringinase treatment could maintain the aroma profile close to the original,

fresh juice. Copyright © 2015 John Wiley & Sons, Ltd.

Additional supporting information may be found in the online version of this article at the publisher’s web site.

Keywords: pummelo juice; naringinase treatment; resin adsorption; aroma; GC-MS; sensory evaluation

Introduction

Citrus includes a group of popular fruits that are widely cultivated

all over the world with significant economic values.[1] Although

some citrus fruits (e.g. sweet orange) can be processed into many

desirable juices, some citrus species, e.g. grapefruits, sour oranges

and pummelo fruits, are traditionally considered inferior to other

species and non-suitable for making commercial juices owing to

their inherent undesirable bitter taste, which is mainly ascribed

to the compound naringin.[2,3]

Naringin is a flavanone glycoside that has a low threshold of the

bitter taste and often exists at high concentrations in some citrus

fruits, e.g. grape fruit and pummel.[4] It has been reported that

naringin in citrus juice can be removed using several methods,

among which resin adsorption and enzymatic hydrolysis are the

most commonly used techniques owing to their advantages in

light of a simple operation and labor-cost efficiency.[5,6] Resin ad￾sorption has been reported to be able to capture the naringin as

well as some nutrients and aroma chemicals, which inevitably

and negatively impacts the juice quality.[7] By contrast, the enzy￾matic process seems to have less influence on the juice nutrients

and aroma compounds because the enzyme (i.e. naringinase) spe￾cifically hydrolyzes the substrate naringin under a modest condi￾tion. However, during the enzymatic processing, juices are

subjected to thermal incubation and oxygen exposure that may

cause evaporation, oxidation and degradation of the nutrients

and aroma compounds. As far as we know, the effect of the enzy￾matic debittering process on the nutrients and aroma compounds

of citrus juices has not been investigated yet.

Pummelo is botanically named Citrus grandis or Citrus maxima

(in Japan). It is also called pample mousse, pomelo, Bali lemon,

Limau besar and shaddock[8] and is one of the major native citrus

species of Southeast Asia.[9] In general, pummelo fruits are well

known to contain remarkable amounts of naringin as well limonin,

which consequently bring a strong undesirable bitter taste that

should be removed in order to make them a commercially desir￾able juice.[9] For example, Ni et al.

[10] reported that pummelo juice

contained 338.2 μg/ml naringin and 117.1 μg/ml limonin, which

are much higher than their thresholds.

In our previous studies, two naringinases were prepared and

characterized to remove the naringin in citrus juices.[11,12] In

addition, a combined treatment of pectinase and naringinase

was proposed to extract the pummelo juice.[10] With regards to

the expanding application of naringinase to remove the bitter

* Correspondence to: Professor Feng Chen, Department of Food, Nutrition and

Packaging Sciences, Clemson University, Clemson, SC 29634, USA. E-mail:

[email protected]

a College of Food and Biology Engineering, Jimei University, Fujian Province,

361021, China

b Department of Food, Nutrition and Packaging Sciences, Clemson University,

Clemson, SC, 29634, USA

c Fujian Provincial Key Laboratory of Food Microbiology and Enzyme Engineer￾ing, Xiamen, Fujian Province, 361021, China

d Research Center of Food Biotechnology of Xiamen City, Xiamen 361021, China

Flavour Fragr. J. 2015, 30, 245–253 Copyright © 2015 John Wiley & Sons, Ltd.

Research Article

Received: 12 August 2014, Revised: 20 January 2015, Accepted: 21 January 2015 Published online in Wiley Online Library: 10 March 2015

(wileyonlinelibrary.com) DOI 10.1002/ffj.3239

245