Pepper (Capsicum annuum L.) is one of the most significant vegetable plants in Western Balkans. Production of Spice paprika in the region of Pannonian plate has a long tradition. First printed manual for producing pepper fruits for ground papprika and for pepper fruits processing in Serbia was published at the begining of the XIX century (Ivković, 1933; Ivačković,1938). Pepper fruits are predominantly sold on market as a fresh fruits, but consumption of processed pepper fruits is also very significant. One of the very important products of pepper processing is ground paprika, a spice which is widely used trough the World. The main quality parameters for ground paprika products are the color and pungency (Carvajal et al., 1998; Govindarijan, 1986; Govindarijan et al., 1987), while aroma recently started to attract the attention of scientists (Mateo et al., 1997; Cremer and Eichner, 2000; Kocsis et al., 2002; 2003).

In the process of food production paprika is mainly used as a colorant. Unique red color of paprika is due to presence of capsantin and capsorubin, two carotenoids characteristic for the capsicum genus. Besides changing the color of the food, paprika also affect the flavor. During processing of Spanish paprika, pepper fruits are smoked during drying which gives them a specific aroma. Ground paprika aroma from Pannonian plate region consists only of naturally occurring compounds. According to Kocsis et al. (2002, 2003) chemical classes which can be found in ground paprika essential oil are: terpenes and their derivates, alcohols, aldehydes, ketones, acids, esters, benzene derivates, naphthalene skeleton compounds, hydrocarbons, sulphur compounds, phenolic compounds, nitrogen containing substances and carotenoid derivates. They have specific aroma, which can be sensed by humans in relatively low concentrations.

Having in mind development of tools for analysis of aromatic compounds (gas chromatography) and especially development of wide rage detectors on one hand and development of new analytical procedures for sample preparation on the other hand aim of this paper is to determine changes of aldehyde composition in essential oil during processing red pepper fruits in order to obtain paprika spice.

In this study pepper cultivar “AlevaNK” for paprika production is used. “Aleva NK” is relatively new cultivar and it is developed to solve problem of multiple fruit collection. As a result, ¾ of fruits are collected in the first harvest and ¼ in the second harvest. For this purpose pepper fruits were sampled from field intended for mercantile production. Pepper fruits were sampled in the stage of intensive red color. Sampled fruits were divided in four equal groups. First group was used immediately for analysis as fresh while the second group was left for two days and then dried in a laboratory dryer with fitted fan at 60±5 °C. Third and fourth group were left for 15 days for the postharvest treatment. Postharvest treatment was done in a glass-house under semicontrolled conditions, with a difference in light presence.. The third group was left in the dark and the fourth was exposed to natural sunlight. After the treatment fruits were dried, milled and obtained powder was used for the analyses.

Essential oils were extracted by steam distillation from fresh and dry samples. Extraction was done from 100 g and 30 g of fresh and dried samples, respectively. Before extraction fresh, sample was cut in manageable pieces, and then homogenized with 500 ml of water, while dried samples were only mixed with same quantity of water before distillation. Due to the small amounts of essential oils, 1 ml of hexane was added to the samples. Distillation time was 90 minutes and obtained organic phase was collected and kept at -20 °C under inert atmosphere (N2) until further use.

Separation of aldehydes from pepper fruit essential oils was done under following conditions:

• Instrument: Thermo Finnigan Trace GC – Trace MS
• Interface temperature: 280 °C
• Ion source temperature: 230 °C
• Carrier: He, flow: 1.5 ml min-1
• Injector: PTV Splitless, t=250 °C,
• Injected volume 1 µL
• Ion source: EI, 70 eV

Column and temperature settings for fresh pepper:

• Column: 30 m × 0,25 mm, PS 255, MEGA, Italy
• Film thickness: 0,25 μm
• Initial temperature: 50 °C
• Temperature program: linear, 4 °C minute-1
• Final temperature: 280 °C

Column and temperature settings for dry pepper:

• Column: 60 m × 0.25 mm, J&W DB, 5MS, Agilent, USA
• Film thickness: 0.25 μm
• Initial temperature: 50 °C
• Temperature program: linear, 2 °C minute-1
• Final temperature: 280 °C

RESULTS AND DISCUSSION

Aldehydes	Fresh	Dried	15 days on dark	15 days on light
Benzaldehyde	+	+	+	+
p- Methyl Benzaldehyde		+	+	+
Hexanal			+	+
2-Hexenal		+	+	+
Heptanal		+	+	+
2-Heptanal		+	+	+
trans-2-Octenal		+	+	+
2,6-Nonadienal	+
Nonanal		+	+	+
2-trans-6-cis-Nonadienal		+	+	+
2-Nonenal	+	+	+	+
Safranal		+	+	+
Decanal	+	+	+	+
2,4-Decadienal	+	+	+	+
Tetradecanal (myristyl aldehyde)	+	+	+	+
10-Undecanal	+
Hexadecanal	+
Pentadecanal		+	+	+
Tetradecanal		+	+	+
9,17-Oktadecadienal	+	+	+	+
9-Octadecenal	+

Mateo et al. (1997) and Zimmerman and Schieberle (2000) extracted volatiles from Spanish paprika with diethylether while Kocsis et al. (2002; 2003) extracted essential oils by steam distillation. Based on that, the sample preparation could be an argument for those differences.

Using steam distillation of fresh and dry samples of pepper followed by GC/MS separation and identification, 26 aldehyds were identified in AlevaNK cultivar. Referring to the obtained results, great difference between fresh and dry pepper samples exist, while only minor difference was observed between dry saples. Only six aldehydes were common to fresh and dried samples. The investigated cultivar has similar aldehyde compounds to Hungarian paprika, but non of the identified aldehydes were reported for Spanish paprika.