## 4 Applications in Food Analysis
### Aroma  
The verification of taste and fragrance attributed to specific foods has become an important part of consumer demand. For this purpose SPME methods can serve as a valuable tool to examine the presence or absence of desired aroma compounds in food products [65]. SPME has gained increasing popularity for aroma analysis in recent years (see Figure 8). A collection of recently published studies in the field of applications of SPME in food, non-food, and fragrance analysis, _etc._ are listed in the Handbook of Solid Phase Microextraction [75]. Various food components like proteins, lipids, and sugars affect the chemical composition found in the headspace above food items. [PERSON] and [PERSON] (1993) reported that the presence of a large quantity of lipid material in food products led to a lower extraction of volatiles from the headspace [299]. To prevent this decrease it is recommended to carefully raise the extraction temperature that will increase the number of volatile constituents present in the headspace. Thereby the number of volatile constituents present in the headspace increase. Raw meat for example had no strong aroma [300], but cooking increased meat aroma [300]. [PERSON] _et al._ (2008) studied compounds that have a real impact on meat aroma. Volatiles of the roasted Mini-pig pork were determined by both SPME and SDE combined with GC-MS. Additionally GC-O was applied to identify potent contributors to the special meat aroma. A total of 86 different volatile compounds have been identified, whereas only 45 odor active regions could be recognized by olfactometry. Aldehydes from lipid oxidation followed by spice components were among the highest contributors to the volatile chemical profile [205]. Another study on meat aroma was performed with Chinese traditional smoke-cured bacon (CSCB) by [PERSON] _et al._[206]. The aim of the study was to work out the substances responsible for the characteristic aroma of CSCB. In total, 48 volatile compounds (alkanes, aldehydes, ketones, alcohols, thiolethers and thiols, furans and phenol compounds) were identified and quantified using SPME coupled to GC-MS [206]. Chemical processes like smoking, oxidation and the Maillard reaction (reaction between reducing sugars and amino acids, usually under the influence of heat) are largely responsible for the occurrence of these compounds. Another approach in aroma analysis is to verify the origin and authenticity of foods. For example, [PERSON] _et al._[202] developed a SPME method in combination with chemometrics for the determination of volatile compounds derived from traditional Polish cheese Oscypek and its imitations [202]. [PERSON] _et al._ (2000) used SPME-GC-MS to differentiate between natural vanilla extracts and nature-identical and synthetic vanilla flavorings [301]. The extraction of aromatic volatile compounds from alcoholic and non-alcoholic beverages by SPME was recently extensively investigated (see table 3). [PERSON] _et al._[212] investigated aroma compounds in whisky samples. Classical analytical methods such as LLE, simultaneous extraction or distillation show relatively low reproducibility or possible contamination with solvents. Further the lengh of time required for the analysis and the selectivity of the results are such a few drawbacks, which can be overcome selectivity can be overcome by dynamic headspace SPME and gas chromatography coupled to GC-MS. In this study the use of five different SPME fibers PDMS, PA, CAR-PDMS, CW-DVB and CAR-PDMS-DVB were compared. Optimized results were achieved by saturating the samples with salt solutions and using a CAR-PDMS fiber. More than seventy compounds including ethylesters, long-chain alcohols, isoamyl acetates and fatty acids were identified [212]. [PERSON] _et al_. [231] investigated volatile compounds derived from jackfruit applying SPME and gas chromatography-time-of-flight mass spectrometry (GCTOF-MS). In five jackfruit cultivars thirty-seven compounds were identified.