_ Food Science and Technology Research, 23 (1), 79 89, 2017 Copyright © 2017, Japanese Society for Food Science and Technology doi: 10.3136/fstr.23.79 http://www.jsfst.or.jp Original paper Comparison of Volatile Compounds in ‘Fuji’ Apples in the Different Regions in China 1 2* 3 2 2 2 Ling QIN , Qin-Ping WEI , Wen-Huai KANG , Qiang ZHANG , Jian SUN and Song-Zhong LIU 1Department of Life Science, Hebei Normal University of Science and Technology, Qinhuangdao 066004 P. R. China 2Institute of Forestry & Pomology, Beijing Academy of Agriculture & Forestry Sciences,Beijing 100093 P.R. China 3College of Bioscience and Bioengineering, Hebei University of Science and Technology, Shijiazhuang 050018 P.R. China Received May 25, 2015 ; Accepted September 28, 2016 The characteristics of the volatiles from 43 ‘Fuji’ apples representing 14 different apple production regions in China were investigated using headspace-solid phase micro-extraction (HS-SPME) combined with gas chromatography–mass spectrometry (GC-MS). The results obtained from this experiment showed that sixty- four volatile compounds were identified in ‘Fuji’ apples collected from 43 counties in China. The major volatile compounds were identified as 2-methyl butyl acetate and hexyl acetate. The composition of volatiles and their contents in ‘Fuji’ apples varied in different regions. All of the ‘Fuji’ apple samples could be classified into the following groups using a principal component analysis of the volatiles: (1) apples with high concentrations of hexyl acetate and (Z)-3-hexenyl acetate, which were collected in Shandong (Qixia, Wendeng, Penglai, Zhaoyuan, Jiaonan and Yishui), Shanxi (Wanrong, Ruicheng and Linyi), and Gansu Ninglang, (2) apples with high contents of 2-methyl butyl acetate and 1-hexanol, which mainly came from North Shaanxi, Henan Sanmenxia, Liaoning Wafangdian and Liaoning Suizhong, (3) apples with high contents of hexyl butanoate, butyl acetate and hexyl 2-methyl butyrate, which were mainly collected in Gansu (excluding Ninglang), and (4) apples without any characteristic volatile composition. In addition, it was found that mean annual temperature was significant correlated with 2-methyl butyl acetate,butyl 2-methyl butanoate, hexyl acetate, and (E)-2-hexenyl acetate. Longitude was significantly correlated with butyl acetate, (Z)-3-hexenyl acetate, and ethyl hexanoate. Keywords: Apple (Malus domestica), aroma compounds, GC-MS (gas chromatography-mass spectrometry), HS-SPME (headspace - solid phase microextraction) Introduction chains including combinations of acetic, butanoic, and hexanoic Aroma is one of the essential components of fruit quality. The acids with ethyl, butyl, and hexyl alcohols, have been reported to relative contributions of specific aroma volatile compounds to the be the major contributors to the aroma of apples (López, Lavilla, flavor of apples have been examined by many investigators, and Riba & Vendrell, 1998; Matich, Rowan & Banks, 1996; Song & more than 300 compounds have been identified (Dixon & Hewett, Bangerth, 1993). 2000; Elss, Preston, Appel, Heckel & Schreier, 2006; Fallik, Investigations have focused on the characteristic volatiles Archbold, Hamilton-Kemp, Loughrin & Collins, 1997; Mehinagic, produced by ripening apples and the evolution of apple aromas Royer, Symoneaux, Jourjon & Prost, 2006). The volatile post-harvest (Bangerth, Song & Streif, 2012; Echeverrıa, Graell, compounds of apples (Malus domestica Borkh) include alcohols, López & Lara, 2004; Song et al., 1993). Bangerth and colleagues aldehydes, carboxylic esters, ketones, and ethers (Dixon et al., (Bangerth et al., 2012) reviewed physiological impacts of fruit 2000). The esters, particularly those with even numbered carbon ripening and storage conditions on the formation of aroma volatiles *To whom correspondence should be addressed. E-mail: [email protected] 80 L. QIN et al. in apples. Apple volatile production had been categorized from the above locations when the apples were fully ripe (based on according to: type and quantity of esters or alcohols (Dirinck & the days after full bloom). Forty fruits per orchard were sampled Schamp, 1988; Paillard, 1990), skin color (Paillard, 1979), or according to an equatorial pattern (East–West–North–South) from aroma production patterns (Dirinck et al., 1988). Several studies the periphery of the canopy of each tree individually, avoiding (Defilippi, Kader & Dandekar, 2005; Elss et al., 2006; Matich et fruits situated at the top, bottom or deep inside the foliage. The al., 1996; Schaffer et al., 2007; Schumacher, Asche, Heil, sampled fruits were healthy and without any symptoms of pest Mittelstädt, Dietrich & Mosandl, 1998; Song & Bangerth, 2003; infestation or disease infection. The sampled fruits were put into Xiaobo & Jiewen, 2008) have discussed the biochemical origin of plastic bags and transferred to the laboratory in an insulated box aroma volatiles and improvements in methods for the separation filled with ice packs. In the laboratory the apple samples were and identification of volatile compounds. Several studies washed in deionised water and surface-dried with gauze. (Mpelasoka & Hossein Behboudian, 2002; Nielsen, Jägerstad, Öste Analysis of aroma volatile compounds Two kilograms of & Wesslén, 1992; Plotto, McDaniel & Mattheis, 1999; Song et al., sampled fruits from each location were ground to a powder and 1993) have also investigated the effect of culture techniques and homogenized using a blender. Juice from the collected apples was management on the composition and content of volatiles. ‘Fuji’ centrifuged at 4000 rpm for 10 min. The supernatant was stored at apple cultivar (Malus domestica Borkh CV. Red Fuji) is becoming -80℃ until analysis. Volatiles from the apple juice samples were one of the major apple cultivars in China, and it is grown both in extracted using HS-SPME. A 50/30 µm DVB / CAR / PDMS fiber northern and southern China. In the two dominant apples (Tupelo, Inc., Bellefonte, PA) was used for aroma extraction. production zones in China, the Loess Plateau regions and Apple juice (8 g) was weighed in a 20 mL headspace vial and Surrounding Bohai Gulf regions, the cultivated area of ‘Fuji’ capped with a septum. The juice was saturated with sodium apples has exceeded 80%. Until now, there have been no reports on chloride (2.4 g) and a 2-octanol internal standard solution was aroma volatile characteristic and quality parameters in different added to each vial to give a final 2-octanol concentration of 80 µg _ apple production regions. L 1. In this study, headspace-solid phase micro-extraction (HS- Each sample was equilibrated at 45℃ in a thermostatic bath for SPME) combined with gas chromatography – mass spectrometry 45 min, and then extracted for 30 min at the same temperature (GC-MS) was applied to study the volatiles compounds in ‘Fuji’ while stirring. After extraction, the fiber was inserted into the apples in the different production regions in China. The aim of this injection port of the GC (250℃) to adsorb the analysis. GC-MS work focused on comparing the aroma composition and content, was carried out using an Agilent GC 6890-5975 Mass Selective which was used to assess aroma volatile characteristic and quality Detector (MSD). Samples were analyzed on a DB-Wax column parameters in ‘Fuji’ apples, particularly among the different apple (30 m × 0.32 mm I.D., 0.25 µm film thickness; J&W Scientific, production regions in China that have not been extensively studied. Folsom, CA, and USA). Helium was used as the carrier gas at a constant flow rate of 2 mL/min. The oven temperature was Materials and Methods maintained at 50℃ for 2 min then the temperature was increased to Plant materials ‘Fuji’ apple (Malus domestica Borkh CV. 230℃ and maintained for 25 min. The MS detector was operated Red Fuji) samples were collected from October 30 through in the scan mode (mass range 50-200) and the transfer line to the November 6, 2011 in 43 well-managed orchards located in 14 MS system was maintained at 250℃ apple production regions in China. Twenty-one ‘Fuji’ fruits Identification of volatile compounds was based on the samples came from the Loess Plateau, which included the comparison of their mass spectra and retention indices (RI) with following locations: three East Gansu areas, four Gansu Tianshui standards and published data, as well as standard mass spectra in areas, three North Shaanxi areas, four Shaanxi Guanzhong areas, the NIST05a. L database (Agilent Technologies Inc.). Retention one collection from Lingwu Ningxia, five middle and south Shanxi indices were calculated using a mixture of n-paraffin C6-C30 as locations, and one collection from Sanmenxia Henan. Twenty-two standards. The volatile compound content was calculated from the ‘Fuji’ apple samples came from areas surrounding the Bohai Gulf, GC-peak areas that relate to the GC-peak area of the internal including six locations in southern and western Liaoning, five in standard. the Hebei Yanshan mountainous area, five in the Shandong Statistical analysis Data for each apple sample were averaged Peninsula, three in the Shandong TaiYi mountainous areas, and one among the three replications. A principal component analysis collection from Changping, Beijing. Two apple samples came from (PCA) was done to detect clustering formations and establish other regions, one from Malong Yunnan and one from Fengxian relationships between samples and volatile compounds using SPSS Jiangsu. Table 1 gives the geographical location and main climatic for Windows Version